279a22f96e
Implement refcounter based data protection guard to avoid unnecessary calls to mprotect when dlopen/dlclose is called from a constructor. Bug: 19124318 Big: 7941716 Change-Id: Id221b84ce75443094f99756dc9950b0a1dc87222
2703 lines
83 KiB
C++
2703 lines
83 KiB
C++
/*
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* Copyright (C) 2008, 2009 The Android Open Source Project
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <dlfcn.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <inttypes.h>
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#include <pthread.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/mman.h>
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#include <sys/param.h>
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#include <sys/personality.h>
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#include <unistd.h>
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#include <new>
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// Private C library headers.
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#include "private/bionic_tls.h"
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#include "private/KernelArgumentBlock.h"
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#include "private/ScopedPthreadMutexLocker.h"
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#include "private/ScopedFd.h"
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#include "private/ScopeGuard.h"
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#include "private/UniquePtr.h"
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#include "linker.h"
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#include "linker_debug.h"
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#include "linker_environ.h"
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#include "linker_phdr.h"
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#include "linker_relocs.h"
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#include "linker_allocator.h"
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/* >>> IMPORTANT NOTE - READ ME BEFORE MODIFYING <<<
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*
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* Do NOT use malloc() and friends or pthread_*() code here.
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* Don't use printf() either; it's caused mysterious memory
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* corruption in the past.
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* The linker runs before we bring up libc and it's easiest
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* to make sure it does not depend on any complex libc features
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*
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* open issues / todo:
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*
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* - cleaner error reporting
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* - after linking, set as much stuff as possible to READONLY
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* and NOEXEC
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*/
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// Override macros to use C++ style casts
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#undef ELF_ST_TYPE
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#define ELF_ST_TYPE(x) (static_cast<uint32_t>(x) & 0xf)
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#if defined(__LP64__)
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#define SEARCH_NAME(x) x
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#else
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// Nvidia drivers are relying on the bug:
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// http://code.google.com/p/android/issues/detail?id=6670
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// so we continue to use base-name lookup for lp32
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static const char* get_base_name(const char* name) {
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const char* bname = strrchr(name, '/');
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return bname ? bname + 1 : name;
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}
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#define SEARCH_NAME(x) get_base_name(x)
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#endif
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static ElfW(Addr) get_elf_exec_load_bias(const ElfW(Ehdr)* elf);
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static LinkerAllocator<soinfo> g_soinfo_allocator;
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static LinkerAllocator<LinkedListEntry<soinfo>> g_soinfo_links_allocator;
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static soinfo* solist;
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static soinfo* sonext;
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static soinfo* somain; // main process, always the one after libdl_info
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static const char* const kDefaultLdPaths[] = {
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#if defined(__LP64__)
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"/vendor/lib64",
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"/system/lib64",
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#else
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"/vendor/lib",
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"/system/lib",
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#endif
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nullptr
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};
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#define LDPATH_BUFSIZE (LDPATH_MAX*64)
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#define LDPATH_MAX 8
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#define LDPRELOAD_BUFSIZE (LDPRELOAD_MAX*64)
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#define LDPRELOAD_MAX 8
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static char g_ld_library_paths_buffer[LDPATH_BUFSIZE];
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static const char* g_ld_library_paths[LDPATH_MAX + 1];
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static char g_ld_preloads_buffer[LDPRELOAD_BUFSIZE];
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static const char* g_ld_preload_names[LDPRELOAD_MAX + 1];
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static soinfo* g_ld_preloads[LDPRELOAD_MAX + 1];
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__LIBC_HIDDEN__ int g_ld_debug_verbosity;
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__LIBC_HIDDEN__ abort_msg_t* g_abort_message = nullptr; // For debuggerd.
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#if STATS
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struct linker_stats_t {
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int count[kRelocMax];
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};
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static linker_stats_t linker_stats;
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void count_relocation(RelocationKind kind) {
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++linker_stats.count[kind];
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}
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#else
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void count_relocation(RelocationKind) {
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}
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#endif
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#if COUNT_PAGES
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uint32_t bitmask[4096];
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#endif
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// You shouldn't try to call memory-allocating functions in the dynamic linker.
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// Guard against the most obvious ones.
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#define DISALLOW_ALLOCATION(return_type, name, ...) \
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return_type name __VA_ARGS__ \
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{ \
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__libc_fatal("ERROR: " #name " called from the dynamic linker!\n"); \
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}
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DISALLOW_ALLOCATION(void*, malloc, (size_t u __unused));
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DISALLOW_ALLOCATION(void, free, (void* u __unused));
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DISALLOW_ALLOCATION(void*, realloc, (void* u1 __unused, size_t u2 __unused));
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DISALLOW_ALLOCATION(void*, calloc, (size_t u1 __unused, size_t u2 __unused));
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static char __linker_dl_err_buf[768];
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char* linker_get_error_buffer() {
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return &__linker_dl_err_buf[0];
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}
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size_t linker_get_error_buffer_size() {
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return sizeof(__linker_dl_err_buf);
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}
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// This function is an empty stub where GDB locates a breakpoint to get notified
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// about linker activity.
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extern "C" void __attribute__((noinline)) __attribute__((visibility("default"))) rtld_db_dlactivity();
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static pthread_mutex_t g__r_debug_mutex = PTHREAD_MUTEX_INITIALIZER;
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static r_debug _r_debug = {1, nullptr, reinterpret_cast<uintptr_t>(&rtld_db_dlactivity), r_debug::RT_CONSISTENT, 0};
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static link_map* r_debug_tail = 0;
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static void insert_soinfo_into_debug_map(soinfo* info) {
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// Copy the necessary fields into the debug structure.
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link_map* map = &(info->link_map_head);
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map->l_addr = info->load_bias;
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map->l_name = info->name;
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map->l_ld = info->dynamic;
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// Stick the new library at the end of the list.
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// gdb tends to care more about libc than it does
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// about leaf libraries, and ordering it this way
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// reduces the back-and-forth over the wire.
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if (r_debug_tail) {
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r_debug_tail->l_next = map;
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map->l_prev = r_debug_tail;
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map->l_next = 0;
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} else {
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_r_debug.r_map = map;
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map->l_prev = 0;
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map->l_next = 0;
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}
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r_debug_tail = map;
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}
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static void remove_soinfo_from_debug_map(soinfo* info) {
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link_map* map = &(info->link_map_head);
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if (r_debug_tail == map) {
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r_debug_tail = map->l_prev;
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}
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if (map->l_prev) {
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map->l_prev->l_next = map->l_next;
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}
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if (map->l_next) {
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map->l_next->l_prev = map->l_prev;
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}
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}
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static void notify_gdb_of_load(soinfo* info) {
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if (info->is_main_executable()) {
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// GDB already knows about the main executable
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return;
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}
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ScopedPthreadMutexLocker locker(&g__r_debug_mutex);
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_r_debug.r_state = r_debug::RT_ADD;
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rtld_db_dlactivity();
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insert_soinfo_into_debug_map(info);
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_r_debug.r_state = r_debug::RT_CONSISTENT;
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rtld_db_dlactivity();
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}
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static void notify_gdb_of_unload(soinfo* info) {
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if (info->is_main_executable()) {
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// GDB already knows about the main executable
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return;
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}
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ScopedPthreadMutexLocker locker(&g__r_debug_mutex);
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_r_debug.r_state = r_debug::RT_DELETE;
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rtld_db_dlactivity();
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remove_soinfo_from_debug_map(info);
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_r_debug.r_state = r_debug::RT_CONSISTENT;
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rtld_db_dlactivity();
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}
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void notify_gdb_of_libraries() {
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_r_debug.r_state = r_debug::RT_ADD;
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rtld_db_dlactivity();
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_r_debug.r_state = r_debug::RT_CONSISTENT;
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rtld_db_dlactivity();
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}
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LinkedListEntry<soinfo>* SoinfoListAllocator::alloc() {
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return g_soinfo_links_allocator.alloc();
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}
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void SoinfoListAllocator::free(LinkedListEntry<soinfo>* entry) {
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g_soinfo_links_allocator.free(entry);
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}
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static soinfo* soinfo_alloc(const char* name, struct stat* file_stat, off64_t file_offset, uint32_t rtld_flags) {
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if (strlen(name) >= SOINFO_NAME_LEN) {
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DL_ERR("library name \"%s\" too long", name);
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return nullptr;
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}
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soinfo* si = new (g_soinfo_allocator.alloc()) soinfo(name, file_stat, file_offset, rtld_flags);
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sonext->next = si;
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sonext = si;
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TRACE("name %s: allocated soinfo @ %p", name, si);
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return si;
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}
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static void soinfo_free(soinfo* si) {
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if (si == nullptr) {
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return;
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}
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if (si->base != 0 && si->size != 0) {
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munmap(reinterpret_cast<void*>(si->base), si->size);
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}
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soinfo *prev = nullptr, *trav;
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TRACE("name %s: freeing soinfo @ %p", si->name, si);
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for (trav = solist; trav != nullptr; trav = trav->next) {
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if (trav == si) {
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break;
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}
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prev = trav;
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}
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if (trav == nullptr) {
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// si was not in solist
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DL_ERR("name \"%s\"@%p is not in solist!", si->name, si);
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return;
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}
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// clear links to/from si
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si->remove_all_links();
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// prev will never be null, because the first entry in solist is
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// always the static libdl_info.
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prev->next = si->next;
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if (si == sonext) {
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sonext = prev;
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}
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g_soinfo_allocator.free(si);
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}
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static void parse_path(const char* path, const char* delimiters,
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const char** array, char* buf, size_t buf_size, size_t max_count) {
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if (path == nullptr) {
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return;
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}
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size_t len = strlcpy(buf, path, buf_size);
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size_t i = 0;
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char* buf_p = buf;
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while (i < max_count && (array[i] = strsep(&buf_p, delimiters))) {
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if (*array[i] != '\0') {
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++i;
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}
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}
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// Forget the last path if we had to truncate; this occurs if the 2nd to
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// last char isn't '\0' (i.e. wasn't originally a delimiter).
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if (i > 0 && len >= buf_size && buf[buf_size - 2] != '\0') {
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array[i - 1] = nullptr;
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} else {
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array[i] = nullptr;
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}
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}
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static void parse_LD_LIBRARY_PATH(const char* path) {
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parse_path(path, ":", g_ld_library_paths,
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g_ld_library_paths_buffer, sizeof(g_ld_library_paths_buffer), LDPATH_MAX);
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}
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static void parse_LD_PRELOAD(const char* path) {
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// We have historically supported ':' as well as ' ' in LD_PRELOAD.
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parse_path(path, " :", g_ld_preload_names,
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g_ld_preloads_buffer, sizeof(g_ld_preloads_buffer), LDPRELOAD_MAX);
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}
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#if defined(__arm__)
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// For a given PC, find the .so that it belongs to.
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// Returns the base address of the .ARM.exidx section
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// for that .so, and the number of 8-byte entries
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// in that section (via *pcount).
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//
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// Intended to be called by libc's __gnu_Unwind_Find_exidx().
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//
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// This function is exposed via dlfcn.cpp and libdl.so.
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_Unwind_Ptr dl_unwind_find_exidx(_Unwind_Ptr pc, int* pcount) {
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uintptr_t addr = reinterpret_cast<uintptr_t>(pc);
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for (soinfo* si = solist; si != 0; si = si->next) {
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if ((addr >= si->base) && (addr < (si->base + si->size))) {
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*pcount = si->ARM_exidx_count;
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return reinterpret_cast<_Unwind_Ptr>(si->ARM_exidx);
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}
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}
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*pcount = 0;
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return nullptr;
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}
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#endif
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// Here, we only have to provide a callback to iterate across all the
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// loaded libraries. gcc_eh does the rest.
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int dl_iterate_phdr(int (*cb)(dl_phdr_info* info, size_t size, void* data), void* data) {
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int rv = 0;
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for (soinfo* si = solist; si != nullptr; si = si->next) {
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dl_phdr_info dl_info;
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dl_info.dlpi_addr = si->link_map_head.l_addr;
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dl_info.dlpi_name = si->link_map_head.l_name;
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dl_info.dlpi_phdr = si->phdr;
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dl_info.dlpi_phnum = si->phnum;
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rv = cb(&dl_info, sizeof(dl_phdr_info), data);
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if (rv != 0) {
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break;
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}
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}
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return rv;
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}
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ElfW(Sym)* soinfo::find_symbol_by_name(SymbolName& symbol_name) {
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return is_gnu_hash() ? gnu_lookup(symbol_name) : elf_lookup(symbol_name);
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}
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static bool is_symbol_global_and_defined(const soinfo* si, const ElfW(Sym)* s) {
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if (ELF_ST_BIND(s->st_info) == STB_GLOBAL ||
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ELF_ST_BIND(s->st_info) == STB_WEAK) {
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return s->st_shndx != SHN_UNDEF;
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} else if (ELF_ST_BIND(s->st_info) != STB_LOCAL) {
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DL_WARN("unexpected ST_BIND value: %d for '%s' in '%s'",
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ELF_ST_BIND(s->st_info), si->get_string(s->st_name), si->name);
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}
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return false;
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}
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ElfW(Sym)* soinfo::gnu_lookup(SymbolName& symbol_name) {
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uint32_t hash = symbol_name.gnu_hash();
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uint32_t h2 = hash >> gnu_shift2_;
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uint32_t bloom_mask_bits = sizeof(ElfW(Addr))*8;
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uint32_t word_num = (hash / bloom_mask_bits) & gnu_maskwords_;
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ElfW(Addr) bloom_word = gnu_bloom_filter_[word_num];
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|
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// test against bloom filter
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if ((1 & (bloom_word >> (hash % bloom_mask_bits)) & (bloom_word >> (h2 % bloom_mask_bits))) == 0) {
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return nullptr;
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}
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|
|
// bloom test says "probably yes"...
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uint32_t n = bucket_[hash % nbucket_];
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if (n == 0) {
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return nullptr;
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}
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do {
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ElfW(Sym)* s = symtab_ + n;
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if (((chain_[n] ^ hash) >> 1) == 0 &&
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strcmp(get_string(s->st_name), symbol_name.get_name()) == 0 &&
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is_symbol_global_and_defined(this, s)) {
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return s;
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}
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} while ((chain_[n++] & 1) == 0);
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return nullptr;
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}
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ElfW(Sym)* soinfo::elf_lookup(SymbolName& symbol_name) {
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uint32_t hash = symbol_name.elf_hash();
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TRACE_TYPE(LOOKUP, "SEARCH %s in %s@%p h=%x(elf) %zd",
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symbol_name.get_name(), name, reinterpret_cast<void*>(base), hash, hash % nbucket_);
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for (uint32_t n = bucket_[hash % nbucket_]; n != 0; n = chain_[n]) {
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ElfW(Sym)* s = symtab_ + n;
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if (strcmp(get_string(s->st_name), symbol_name.get_name()) == 0 && is_symbol_global_and_defined(this, s)) {
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TRACE_TYPE(LOOKUP, "FOUND %s in %s (%p) %zd",
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symbol_name.get_name(), name, reinterpret_cast<void*>(s->st_value),
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static_cast<size_t>(s->st_size));
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return s;
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}
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}
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|
TRACE_TYPE(LOOKUP, "NOT FOUND %s in %s@%p %x %zd",
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symbol_name.get_name(), name, reinterpret_cast<void*>(base), hash, hash % nbucket_);
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|
|
return nullptr;
|
|
}
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|
|
|
soinfo::soinfo(const char* name, const struct stat* file_stat, off64_t file_offset, int rtld_flags) {
|
|
memset(this, 0, sizeof(*this));
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|
|
|
strlcpy(this->name, name, sizeof(this->name));
|
|
flags_ = FLAG_NEW_SOINFO;
|
|
version_ = SOINFO_VERSION;
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|
|
|
if (file_stat != nullptr) {
|
|
this->st_dev_ = file_stat->st_dev;
|
|
this->st_ino_ = file_stat->st_ino;
|
|
this->file_offset_ = file_offset;
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|
}
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|
|
|
this->rtld_flags_ = rtld_flags;
|
|
}
|
|
|
|
|
|
uint32_t SymbolName::elf_hash() {
|
|
if (!has_elf_hash_) {
|
|
const unsigned char* name = reinterpret_cast<const unsigned char*>(name_);
|
|
uint32_t h = 0, g;
|
|
|
|
while (*name) {
|
|
h = (h << 4) + *name++;
|
|
g = h & 0xf0000000;
|
|
h ^= g;
|
|
h ^= g >> 24;
|
|
}
|
|
|
|
elf_hash_ = h;
|
|
has_elf_hash_ = true;
|
|
}
|
|
|
|
return elf_hash_;
|
|
}
|
|
|
|
uint32_t SymbolName::gnu_hash() {
|
|
if (!has_gnu_hash_) {
|
|
uint32_t h = 5381;
|
|
const unsigned char* name = reinterpret_cast<const unsigned char*>(name_);
|
|
while (*name != 0) {
|
|
h += (h << 5) + *name++; // h*33 + c = h + h * 32 + c = h + h << 5 + c
|
|
}
|
|
|
|
gnu_hash_ = h;
|
|
has_gnu_hash_ = true;
|
|
}
|
|
|
|
return gnu_hash_;
|
|
}
|
|
|
|
ElfW(Sym)* soinfo_do_lookup(soinfo* si_from, const char* name, soinfo** si_found_in,
|
|
const soinfo::soinfo_list_t& global_group, const soinfo::soinfo_list_t& local_group) {
|
|
SymbolName symbol_name(name);
|
|
ElfW(Sym)* s = nullptr;
|
|
|
|
/* "This element's presence in a shared object library alters the dynamic linker's
|
|
* symbol resolution algorithm for references within the library. Instead of starting
|
|
* a symbol search with the executable file, the dynamic linker starts from the shared
|
|
* object itself. If the shared object fails to supply the referenced symbol, the
|
|
* dynamic linker then searches the executable file and other shared objects as usual."
|
|
*
|
|
* http://www.sco.com/developers/gabi/2012-12-31/ch5.dynamic.html
|
|
*
|
|
* Note that this is unlikely since static linker avoids generating
|
|
* relocations for -Bsymbolic linked dynamic executables.
|
|
*/
|
|
if (si_from->has_DT_SYMBOLIC) {
|
|
DEBUG("%s: looking up %s in local scope (DT_SYMBOLIC)", si_from->name, name);
|
|
s = si_from->find_symbol_by_name(symbol_name);
|
|
if (s != nullptr) {
|
|
*si_found_in = si_from;
|
|
}
|
|
}
|
|
|
|
// 1. Look for it in global_group
|
|
if (s == nullptr) {
|
|
global_group.visit([&](soinfo* global_si) {
|
|
DEBUG("%s: looking up %s in %s (from global group)", si_from->name, name, global_si->name);
|
|
s = global_si->find_symbol_by_name(symbol_name);
|
|
if (s != nullptr) {
|
|
*si_found_in = global_si;
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
});
|
|
}
|
|
|
|
// 2. Look for it in the local group
|
|
if (s == nullptr) {
|
|
local_group.visit([&](soinfo* local_si) {
|
|
if (local_si == si_from && si_from->has_DT_SYMBOLIC) {
|
|
// we already did this - skip
|
|
return true;
|
|
}
|
|
|
|
DEBUG("%s: looking up %s in %s (from local group)", si_from->name, name, local_si->name);
|
|
s = local_si->find_symbol_by_name(symbol_name);
|
|
if (s != nullptr) {
|
|
*si_found_in = local_si;
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
});
|
|
}
|
|
|
|
if (s != nullptr) {
|
|
TRACE_TYPE(LOOKUP, "si %s sym %s s->st_value = %p, "
|
|
"found in %s, base = %p, load bias = %p",
|
|
si_from->name, name, reinterpret_cast<void*>(s->st_value),
|
|
(*si_found_in)->name, reinterpret_cast<void*>((*si_found_in)->base),
|
|
reinterpret_cast<void*>((*si_found_in)->load_bias));
|
|
}
|
|
|
|
return s;
|
|
}
|
|
|
|
class ProtectedDataGuard {
|
|
public:
|
|
ProtectedDataGuard() {
|
|
if (ref_count_++ == 0) {
|
|
protect_data(PROT_READ | PROT_WRITE);
|
|
}
|
|
}
|
|
|
|
~ProtectedDataGuard() {
|
|
if (ref_count_ == 0) { // overflow
|
|
__libc_fatal("Too many nested calls to dlopen()");
|
|
}
|
|
|
|
if (--ref_count_ == 0) {
|
|
protect_data(PROT_READ);
|
|
}
|
|
}
|
|
private:
|
|
void protect_data(int protection) {
|
|
g_soinfo_allocator.protect_all(protection);
|
|
g_soinfo_links_allocator.protect_all(protection);
|
|
}
|
|
|
|
static size_t ref_count_;
|
|
};
|
|
|
|
size_t ProtectedDataGuard::ref_count_ = 0;
|
|
|
|
// Each size has it's own allocator.
|
|
template<size_t size>
|
|
class SizeBasedAllocator {
|
|
public:
|
|
static void* alloc() {
|
|
return allocator_.alloc();
|
|
}
|
|
|
|
static void free(void* ptr) {
|
|
allocator_.free(ptr);
|
|
}
|
|
|
|
private:
|
|
static LinkerBlockAllocator allocator_;
|
|
};
|
|
|
|
template<size_t size>
|
|
LinkerBlockAllocator SizeBasedAllocator<size>::allocator_(size);
|
|
|
|
template<typename T>
|
|
class TypeBasedAllocator {
|
|
public:
|
|
static T* alloc() {
|
|
return reinterpret_cast<T*>(SizeBasedAllocator<sizeof(T)>::alloc());
|
|
}
|
|
|
|
static void free(T* ptr) {
|
|
SizeBasedAllocator<sizeof(T)>::free(ptr);
|
|
}
|
|
};
|
|
|
|
class LoadTask {
|
|
public:
|
|
struct deleter_t {
|
|
void operator()(LoadTask* t) {
|
|
TypeBasedAllocator<LoadTask>::free(t);
|
|
}
|
|
};
|
|
|
|
typedef UniquePtr<LoadTask, deleter_t> unique_ptr;
|
|
|
|
static deleter_t deleter;
|
|
|
|
static LoadTask* create(const char* name, soinfo* needed_by) {
|
|
LoadTask* ptr = TypeBasedAllocator<LoadTask>::alloc();
|
|
return new (ptr) LoadTask(name, needed_by);
|
|
}
|
|
|
|
const char* get_name() const {
|
|
return name_;
|
|
}
|
|
|
|
soinfo* get_needed_by() const {
|
|
return needed_by_;
|
|
}
|
|
private:
|
|
LoadTask(const char* name, soinfo* needed_by)
|
|
: name_(name), needed_by_(needed_by) {}
|
|
|
|
const char* name_;
|
|
soinfo* needed_by_;
|
|
|
|
DISALLOW_IMPLICIT_CONSTRUCTORS(LoadTask);
|
|
};
|
|
|
|
LoadTask::deleter_t LoadTask::deleter;
|
|
|
|
template <typename T>
|
|
using linked_list_t = LinkedList<T, TypeBasedAllocator<LinkedListEntry<T>>>;
|
|
|
|
typedef linked_list_t<soinfo> SoinfoLinkedList;
|
|
typedef linked_list_t<const char> StringLinkedList;
|
|
typedef linked_list_t<LoadTask> LoadTaskList;
|
|
|
|
|
|
// This function walks down the tree of soinfo dependencies
|
|
// in breadth-first order and
|
|
// * calls action(soinfo* si) for each node, and
|
|
// * terminates walk if action returns false.
|
|
//
|
|
// walk_dependencies_tree returns false if walk was terminated
|
|
// by the action and true otherwise.
|
|
template<typename F>
|
|
static bool walk_dependencies_tree(soinfo* root_soinfos[], size_t root_soinfos_size, F action) {
|
|
SoinfoLinkedList visit_list;
|
|
SoinfoLinkedList visited;
|
|
|
|
for (size_t i = 0; i < root_soinfos_size; ++i) {
|
|
visit_list.push_back(root_soinfos[i]);
|
|
}
|
|
|
|
soinfo* si;
|
|
while ((si = visit_list.pop_front()) != nullptr) {
|
|
if (visited.contains(si)) {
|
|
continue;
|
|
}
|
|
|
|
if (!action(si)) {
|
|
return false;
|
|
}
|
|
|
|
visited.push_back(si);
|
|
|
|
si->get_children().for_each([&](soinfo* child) {
|
|
visit_list.push_back(child);
|
|
});
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
|
|
// This is used by dlsym(3). It performs symbol lookup only within the
|
|
// specified soinfo object and its dependencies in breadth first order.
|
|
ElfW(Sym)* dlsym_handle_lookup(soinfo* si, soinfo** found, const char* name) {
|
|
ElfW(Sym)* result = nullptr;
|
|
SymbolName symbol_name(name);
|
|
|
|
|
|
walk_dependencies_tree(&si, 1, [&](soinfo* current_soinfo) {
|
|
result = current_soinfo->find_symbol_by_name(symbol_name);
|
|
if (result != nullptr) {
|
|
*found = current_soinfo;
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
});
|
|
|
|
return result;
|
|
}
|
|
|
|
/* This is used by dlsym(3) to performs a global symbol lookup. If the
|
|
start value is null (for RTLD_DEFAULT), the search starts at the
|
|
beginning of the global solist. Otherwise the search starts at the
|
|
specified soinfo (for RTLD_NEXT).
|
|
*/
|
|
ElfW(Sym)* dlsym_linear_lookup(const char* name, soinfo** found, soinfo* start) {
|
|
SymbolName symbol_name(name);
|
|
|
|
if (start == nullptr) {
|
|
start = solist;
|
|
}
|
|
|
|
ElfW(Sym)* s = nullptr;
|
|
for (soinfo* si = start; (s == nullptr) && (si != nullptr); si = si->next) {
|
|
if ((si->get_rtld_flags() & RTLD_GLOBAL) == 0) {
|
|
continue;
|
|
}
|
|
|
|
s = si->find_symbol_by_name(symbol_name);
|
|
if (s != nullptr) {
|
|
*found = si;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (s != nullptr) {
|
|
TRACE_TYPE(LOOKUP, "%s s->st_value = %p, found->base = %p",
|
|
name, reinterpret_cast<void*>(s->st_value), reinterpret_cast<void*>((*found)->base));
|
|
}
|
|
|
|
return s;
|
|
}
|
|
|
|
soinfo* find_containing_library(const void* p) {
|
|
ElfW(Addr) address = reinterpret_cast<ElfW(Addr)>(p);
|
|
for (soinfo* si = solist; si != nullptr; si = si->next) {
|
|
if (address >= si->base && address - si->base < si->size) {
|
|
return si;
|
|
}
|
|
}
|
|
return nullptr;
|
|
}
|
|
|
|
ElfW(Sym)* soinfo::find_symbol_by_address(const void* addr) {
|
|
return is_gnu_hash() ? gnu_addr_lookup(addr) : elf_addr_lookup(addr);
|
|
}
|
|
|
|
static bool symbol_matches_soaddr(const ElfW(Sym)* sym, ElfW(Addr) soaddr) {
|
|
return sym->st_shndx != SHN_UNDEF &&
|
|
soaddr >= sym->st_value &&
|
|
soaddr < sym->st_value + sym->st_size;
|
|
}
|
|
|
|
ElfW(Sym)* soinfo::gnu_addr_lookup(const void* addr) {
|
|
ElfW(Addr) soaddr = reinterpret_cast<ElfW(Addr)>(addr) - base;
|
|
|
|
for (size_t i = 0; i < nbucket_; ++i) {
|
|
uint32_t n = bucket_[i];
|
|
|
|
if (n == 0) {
|
|
continue;
|
|
}
|
|
|
|
do {
|
|
ElfW(Sym)* sym = symtab_ + n;
|
|
if (symbol_matches_soaddr(sym, soaddr)) {
|
|
return sym;
|
|
}
|
|
} while ((chain_[n++] & 1) == 0);
|
|
}
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
ElfW(Sym)* soinfo::elf_addr_lookup(const void* addr) {
|
|
ElfW(Addr) soaddr = reinterpret_cast<ElfW(Addr)>(addr) - base;
|
|
|
|
// Search the library's symbol table for any defined symbol which
|
|
// contains this address.
|
|
for (size_t i = 0; i < nchain_; ++i) {
|
|
ElfW(Sym)* sym = symtab_ + i;
|
|
if (symbol_matches_soaddr(sym, soaddr)) {
|
|
return sym;
|
|
}
|
|
}
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
static int open_library_on_path(const char* name, const char* const paths[]) {
|
|
char buf[512];
|
|
for (size_t i = 0; paths[i] != nullptr; ++i) {
|
|
int n = __libc_format_buffer(buf, sizeof(buf), "%s/%s", paths[i], name);
|
|
if (n < 0 || n >= static_cast<int>(sizeof(buf))) {
|
|
PRINT("Warning: ignoring very long library path: %s/%s", paths[i], name);
|
|
continue;
|
|
}
|
|
int fd = TEMP_FAILURE_RETRY(open(buf, O_RDONLY | O_CLOEXEC));
|
|
if (fd != -1) {
|
|
return fd;
|
|
}
|
|
}
|
|
return -1;
|
|
}
|
|
|
|
static int open_library(const char* name) {
|
|
TRACE("[ opening %s ]", name);
|
|
|
|
// If the name contains a slash, we should attempt to open it directly and not search the paths.
|
|
if (strchr(name, '/') != nullptr) {
|
|
int fd = TEMP_FAILURE_RETRY(open(name, O_RDONLY | O_CLOEXEC));
|
|
if (fd != -1) {
|
|
return fd;
|
|
}
|
|
// ...but nvidia binary blobs (at least) rely on this behavior, so fall through for now.
|
|
#if defined(__LP64__)
|
|
return -1;
|
|
#endif
|
|
}
|
|
|
|
// Otherwise we try LD_LIBRARY_PATH first, and fall back to the built-in well known paths.
|
|
int fd = open_library_on_path(name, g_ld_library_paths);
|
|
if (fd == -1) {
|
|
fd = open_library_on_path(name, kDefaultLdPaths);
|
|
}
|
|
return fd;
|
|
}
|
|
|
|
template<typename F>
|
|
static void for_each_dt_needed(const soinfo* si, F action) {
|
|
for (ElfW(Dyn)* d = si->dynamic; d->d_tag != DT_NULL; ++d) {
|
|
if (d->d_tag == DT_NEEDED) {
|
|
action(si->get_string(d->d_un.d_val));
|
|
}
|
|
}
|
|
}
|
|
|
|
static soinfo* load_library(LoadTaskList& load_tasks, const char* name, int rtld_flags, const android_dlextinfo* extinfo) {
|
|
int fd = -1;
|
|
off64_t file_offset = 0;
|
|
ScopedFd file_guard(-1);
|
|
|
|
if (extinfo != nullptr && (extinfo->flags & ANDROID_DLEXT_USE_LIBRARY_FD) != 0) {
|
|
fd = extinfo->library_fd;
|
|
if ((extinfo->flags & ANDROID_DLEXT_USE_LIBRARY_FD_OFFSET) != 0) {
|
|
file_offset = extinfo->library_fd_offset;
|
|
}
|
|
} else {
|
|
// Open the file.
|
|
fd = open_library(name);
|
|
if (fd == -1) {
|
|
DL_ERR("library \"%s\" not found", name);
|
|
return nullptr;
|
|
}
|
|
|
|
file_guard.reset(fd);
|
|
}
|
|
|
|
if ((file_offset % PAGE_SIZE) != 0) {
|
|
DL_ERR("file offset for the library \"%s\" is not page-aligned: %" PRId64, name, file_offset);
|
|
return nullptr;
|
|
}
|
|
if (file_offset < 0) {
|
|
DL_ERR("file offset for the library \"%s\" is negative: %" PRId64, name, file_offset);
|
|
return nullptr;
|
|
}
|
|
|
|
struct stat file_stat;
|
|
if (TEMP_FAILURE_RETRY(fstat(fd, &file_stat)) != 0) {
|
|
DL_ERR("unable to stat file for the library \"%s\": %s", name, strerror(errno));
|
|
return nullptr;
|
|
}
|
|
if (file_offset >= file_stat.st_size) {
|
|
DL_ERR("file offset for the library \"%s\" >= file size: %" PRId64 " >= %" PRId64, name, file_offset, file_stat.st_size);
|
|
return nullptr;
|
|
}
|
|
|
|
// Check for symlink and other situations where
|
|
// file can have different names.
|
|
for (soinfo* si = solist; si != nullptr; si = si->next) {
|
|
if (si->get_st_dev() != 0 &&
|
|
si->get_st_ino() != 0 &&
|
|
si->get_st_dev() == file_stat.st_dev &&
|
|
si->get_st_ino() == file_stat.st_ino &&
|
|
si->get_file_offset() == file_offset) {
|
|
TRACE("library \"%s\" is already loaded under different name/path \"%s\" - will return existing soinfo", name, si->name);
|
|
return si;
|
|
}
|
|
}
|
|
|
|
if ((rtld_flags & RTLD_NOLOAD) != 0) {
|
|
DL_ERR("library \"%s\" wasn't loaded and RTLD_NOLOAD prevented it", name);
|
|
return nullptr;
|
|
}
|
|
|
|
// Read the ELF header and load the segments.
|
|
ElfReader elf_reader(name, fd, file_offset);
|
|
if (!elf_reader.Load(extinfo)) {
|
|
return nullptr;
|
|
}
|
|
|
|
soinfo* si = soinfo_alloc(SEARCH_NAME(name), &file_stat, file_offset, rtld_flags);
|
|
if (si == nullptr) {
|
|
return nullptr;
|
|
}
|
|
si->base = elf_reader.load_start();
|
|
si->size = elf_reader.load_size();
|
|
si->load_bias = elf_reader.load_bias();
|
|
si->phnum = elf_reader.phdr_count();
|
|
si->phdr = elf_reader.loaded_phdr();
|
|
|
|
if (!si->prelink_image()) {
|
|
soinfo_free(si);
|
|
return nullptr;
|
|
}
|
|
|
|
for_each_dt_needed(si, [&] (const char* name) {
|
|
load_tasks.push_back(LoadTask::create(name, si));
|
|
});
|
|
|
|
return si;
|
|
}
|
|
|
|
static soinfo *find_loaded_library_by_name(const char* name) {
|
|
const char* search_name = SEARCH_NAME(name);
|
|
for (soinfo* si = solist; si != nullptr; si = si->next) {
|
|
if (!strcmp(search_name, si->name)) {
|
|
return si;
|
|
}
|
|
}
|
|
return nullptr;
|
|
}
|
|
|
|
static soinfo* find_library_internal(LoadTaskList& load_tasks, const char* name, int rtld_flags, const android_dlextinfo* extinfo) {
|
|
|
|
soinfo* si = find_loaded_library_by_name(name);
|
|
|
|
// Library might still be loaded, the accurate detection
|
|
// of this fact is done by load_library.
|
|
if (si == nullptr) {
|
|
TRACE("[ '%s' has not been found by name. Trying harder...]", name);
|
|
si = load_library(load_tasks, name, rtld_flags, extinfo);
|
|
}
|
|
|
|
return si;
|
|
}
|
|
|
|
static void soinfo_unload(soinfo* si);
|
|
|
|
// TODO: this is slightly unusual way to construct
|
|
// the global group for relocation. Not every RTLD_GLOBAL
|
|
// library is included in this group for backwards-compatibility
|
|
// reasons.
|
|
//
|
|
// This group consists of the main executable, LD_PRELOADs
|
|
// and libraries with the DF_1_GLOBAL flag set.
|
|
static soinfo::soinfo_list_t make_global_group() {
|
|
soinfo::soinfo_list_t global_group;
|
|
for (soinfo* si = somain; si != nullptr; si = si->next) {
|
|
if ((si->get_dt_flags_1() & DF_1_GLOBAL) != 0) {
|
|
global_group.push_back(si);
|
|
}
|
|
}
|
|
|
|
return global_group;
|
|
}
|
|
|
|
static bool find_libraries(soinfo* start_with, const char* const library_names[], size_t library_names_count, soinfo* soinfos[],
|
|
soinfo* ld_preloads[], size_t ld_preloads_count, int rtld_flags, const android_dlextinfo* extinfo) {
|
|
// Step 0: prepare.
|
|
LoadTaskList load_tasks;
|
|
for (size_t i = 0; i < library_names_count; ++i) {
|
|
const char* name = library_names[i];
|
|
load_tasks.push_back(LoadTask::create(name, start_with));
|
|
}
|
|
|
|
// Construct global_group.
|
|
soinfo::soinfo_list_t global_group = make_global_group();
|
|
|
|
// If soinfos array is null allocate one on stack.
|
|
// The array is needed in case of failure; for example
|
|
// when library_names[] = {libone.so, libtwo.so} and libone.so
|
|
// is loaded correctly but libtwo.so failed for some reason.
|
|
// In this case libone.so should be unloaded on return.
|
|
// See also implementation of failure_guard below.
|
|
|
|
if (soinfos == nullptr) {
|
|
size_t soinfos_size = sizeof(soinfo*)*library_names_count;
|
|
soinfos = reinterpret_cast<soinfo**>(alloca(soinfos_size));
|
|
memset(soinfos, 0, soinfos_size);
|
|
}
|
|
|
|
// list of libraries to link - see step 2.
|
|
size_t soinfos_count = 0;
|
|
|
|
auto failure_guard = make_scope_guard([&]() {
|
|
// Housekeeping
|
|
load_tasks.for_each([] (LoadTask* t) {
|
|
LoadTask::deleter(t);
|
|
});
|
|
|
|
for (size_t i = 0; i<soinfos_count; ++i) {
|
|
soinfo_unload(soinfos[i]);
|
|
}
|
|
});
|
|
|
|
// Step 1: load and pre-link all DT_NEEDED libraries in breadth first order.
|
|
for (LoadTask::unique_ptr task(load_tasks.pop_front()); task.get() != nullptr; task.reset(load_tasks.pop_front())) {
|
|
soinfo* si = find_library_internal(load_tasks, task->get_name(), rtld_flags, extinfo);
|
|
if (si == nullptr) {
|
|
return false;
|
|
}
|
|
|
|
soinfo* needed_by = task->get_needed_by();
|
|
|
|
if (needed_by != nullptr) {
|
|
needed_by->add_child(si);
|
|
}
|
|
|
|
if (si->is_linked()) {
|
|
si->increment_ref_count();
|
|
}
|
|
|
|
// When ld_preloads is not null, the first
|
|
// ld_preloads_count libs are in fact ld_preloads.
|
|
if (ld_preloads != nullptr && soinfos_count < ld_preloads_count) {
|
|
// Add LD_PRELOADed libraries to the global group for future runs.
|
|
// There is no need to explicitly add them to the global group
|
|
// for this run because they are going to appear in the local
|
|
// group in the correct order.
|
|
si->set_dt_flags_1(si->get_dt_flags_1() | DF_1_GLOBAL);
|
|
ld_preloads[soinfos_count] = si;
|
|
}
|
|
|
|
if (soinfos_count < library_names_count) {
|
|
soinfos[soinfos_count++] = si;
|
|
}
|
|
}
|
|
|
|
// Step 2: link libraries.
|
|
soinfo::soinfo_list_t local_group;
|
|
walk_dependencies_tree(
|
|
start_with == nullptr ? soinfos : &start_with,
|
|
start_with == nullptr ? soinfos_count : 1,
|
|
[&] (soinfo* si) {
|
|
local_group.push_back(si);
|
|
return true;
|
|
});
|
|
|
|
// We need to increment ref_count in case
|
|
// the root of the local group was not linked.
|
|
bool was_local_group_root_linked = local_group.front()->is_linked();
|
|
|
|
bool linked = local_group.visit([&](soinfo* si) {
|
|
if (!si->is_linked()) {
|
|
if (!si->link_image(global_group, local_group, extinfo)) {
|
|
return false;
|
|
}
|
|
si->set_linked();
|
|
}
|
|
|
|
return true;
|
|
});
|
|
|
|
if (linked) {
|
|
failure_guard.disable();
|
|
}
|
|
|
|
if (!was_local_group_root_linked) {
|
|
local_group.front()->increment_ref_count();
|
|
}
|
|
|
|
return linked;
|
|
}
|
|
|
|
static soinfo* find_library(const char* name, int rtld_flags, const android_dlextinfo* extinfo) {
|
|
soinfo* si;
|
|
|
|
if (name == nullptr) {
|
|
si = somain;
|
|
} else if (!find_libraries(nullptr, &name, 1, &si, nullptr, 0, rtld_flags, extinfo)) {
|
|
return nullptr;
|
|
}
|
|
|
|
return si;
|
|
}
|
|
|
|
static void soinfo_unload(soinfo* root) {
|
|
// Note that the library can be loaded but not linked;
|
|
// in which case there is no root but we still need
|
|
// to walk the tree and unload soinfos involved.
|
|
//
|
|
// This happens on unsuccessful dlopen, when one of
|
|
// the DT_NEEDED libraries could not be linked/found.
|
|
if (root->is_linked()) {
|
|
root = root->get_local_group_root();
|
|
}
|
|
|
|
if (!root->can_unload()) {
|
|
TRACE("not unloading '%s' - the binary is flagged with NODELETE", root->name);
|
|
return;
|
|
}
|
|
|
|
size_t ref_count = root->is_linked() ? root->decrement_ref_count() : 0;
|
|
|
|
if (ref_count == 0) {
|
|
soinfo::soinfo_list_t local_unload_list;
|
|
soinfo::soinfo_list_t external_unload_list;
|
|
soinfo::soinfo_list_t depth_first_list;
|
|
depth_first_list.push_back(root);
|
|
soinfo* si = nullptr;
|
|
|
|
while ((si = depth_first_list.pop_front()) != nullptr) {
|
|
if (local_unload_list.contains(si)) {
|
|
continue;
|
|
}
|
|
|
|
local_unload_list.push_back(si);
|
|
|
|
if (si->has_min_version(0)) {
|
|
soinfo* child = nullptr;
|
|
while ((child = si->get_children().pop_front()) != nullptr) {
|
|
TRACE("%s@%p needs to unload %s@%p", si->name, si, child->name, child);
|
|
if (local_unload_list.contains(child)) {
|
|
continue;
|
|
} else if (child->is_linked() && child->get_local_group_root() != root) {
|
|
external_unload_list.push_back(child);
|
|
} else {
|
|
depth_first_list.push_front(child);
|
|
}
|
|
}
|
|
} else {
|
|
#ifdef __LP64__
|
|
__libc_fatal("soinfo for \"%s\"@%p has no version", si->name, si);
|
|
#else
|
|
PRINT("warning: soinfo for \"%s\"@%p has no version", si->name, si);
|
|
for_each_dt_needed(si, [&] (const char* library_name) {
|
|
TRACE("deprecated (old format of soinfo): %s needs to unload %s", si->name, library_name);
|
|
soinfo* needed = find_library(library_name, RTLD_NOLOAD, nullptr);
|
|
if (needed != nullptr) {
|
|
// Not found: for example if symlink was deleted between dlopen and dlclose
|
|
// Since we cannot really handle errors at this point - print and continue.
|
|
PRINT("warning: couldn't find %s needed by %s on unload.", library_name, si->name);
|
|
return;
|
|
} else if (local_unload_list.contains(needed)) {
|
|
// already visited
|
|
return;
|
|
} else if (needed->is_linked() && needed->get_local_group_root() != root) {
|
|
// external group
|
|
external_unload_list.push_back(needed);
|
|
} else {
|
|
// local group
|
|
depth_first_list.push_front(needed);
|
|
}
|
|
});
|
|
#endif
|
|
}
|
|
}
|
|
|
|
local_unload_list.for_each([](soinfo* si) {
|
|
si->call_destructors();
|
|
});
|
|
|
|
while ((si = local_unload_list.pop_front()) != nullptr) {
|
|
notify_gdb_of_unload(si);
|
|
soinfo_free(si);
|
|
}
|
|
|
|
while ((si = external_unload_list.pop_front()) != nullptr) {
|
|
soinfo_unload(si);
|
|
}
|
|
} else {
|
|
TRACE("not unloading '%s' group, decrementing ref_count to %zd", root->name, ref_count);
|
|
}
|
|
}
|
|
|
|
void do_android_get_LD_LIBRARY_PATH(char* buffer, size_t buffer_size) {
|
|
// Use basic string manipulation calls to avoid snprintf.
|
|
// snprintf indirectly calls pthread_getspecific to get the size of a buffer.
|
|
// When debug malloc is enabled, this call returns 0. This in turn causes
|
|
// snprintf to do nothing, which causes libraries to fail to load.
|
|
// See b/17302493 for further details.
|
|
// Once the above bug is fixed, this code can be modified to use
|
|
// snprintf again.
|
|
size_t required_len = strlen(kDefaultLdPaths[0]) + strlen(kDefaultLdPaths[1]) + 2;
|
|
if (buffer_size < required_len) {
|
|
__libc_fatal("android_get_LD_LIBRARY_PATH failed, buffer too small: buffer len %zu, required len %zu",
|
|
buffer_size, required_len);
|
|
}
|
|
char* end = stpcpy(buffer, kDefaultLdPaths[0]);
|
|
*end = ':';
|
|
strcpy(end + 1, kDefaultLdPaths[1]);
|
|
}
|
|
|
|
void do_android_update_LD_LIBRARY_PATH(const char* ld_library_path) {
|
|
if (!get_AT_SECURE()) {
|
|
parse_LD_LIBRARY_PATH(ld_library_path);
|
|
}
|
|
}
|
|
|
|
soinfo* do_dlopen(const char* name, int flags, const android_dlextinfo* extinfo) {
|
|
if ((flags & ~(RTLD_NOW|RTLD_LAZY|RTLD_LOCAL|RTLD_GLOBAL|RTLD_NODELETE|RTLD_NOLOAD)) != 0) {
|
|
DL_ERR("invalid flags to dlopen: %x", flags);
|
|
return nullptr;
|
|
}
|
|
if (extinfo != nullptr) {
|
|
if ((extinfo->flags & ~(ANDROID_DLEXT_VALID_FLAG_BITS)) != 0) {
|
|
DL_ERR("invalid extended flags to android_dlopen_ext: 0x%" PRIx64, extinfo->flags);
|
|
return nullptr;
|
|
}
|
|
if ((extinfo->flags & ANDROID_DLEXT_USE_LIBRARY_FD) == 0 &&
|
|
(extinfo->flags & ANDROID_DLEXT_USE_LIBRARY_FD_OFFSET) != 0) {
|
|
DL_ERR("invalid extended flag combination (ANDROID_DLEXT_USE_LIBRARY_FD_OFFSET without ANDROID_DLEXT_USE_LIBRARY_FD): 0x%" PRIx64, extinfo->flags);
|
|
return nullptr;
|
|
}
|
|
}
|
|
|
|
ProtectedDataGuard guard;
|
|
soinfo* si = find_library(name, flags, extinfo);
|
|
if (si != nullptr) {
|
|
si->call_constructors();
|
|
}
|
|
return si;
|
|
}
|
|
|
|
void do_dlclose(soinfo* si) {
|
|
ProtectedDataGuard guard;
|
|
soinfo_unload(si);
|
|
}
|
|
|
|
static ElfW(Addr) call_ifunc_resolver(ElfW(Addr) resolver_addr) {
|
|
typedef ElfW(Addr) (*ifunc_resolver_t)(void);
|
|
ifunc_resolver_t ifunc_resolver = reinterpret_cast<ifunc_resolver_t>(resolver_addr);
|
|
ElfW(Addr) ifunc_addr = ifunc_resolver();
|
|
TRACE_TYPE(RELO, "Called ifunc_resolver@%p. The result is %p", ifunc_resolver, reinterpret_cast<void*>(ifunc_addr));
|
|
|
|
return ifunc_addr;
|
|
}
|
|
|
|
#if !defined(__mips__)
|
|
#if defined(USE_RELA)
|
|
static ElfW(Addr) get_addend(ElfW(Rela)* rela, ElfW(Addr) reloc_addr __unused) {
|
|
return rela->r_addend;
|
|
}
|
|
#else
|
|
static ElfW(Addr) get_addend(ElfW(Rel)* rel, ElfW(Addr) reloc_addr) {
|
|
if (ELFW(R_TYPE)(rel->r_info) == R_GENERIC_RELATIVE || ELFW(R_TYPE)(rel->r_info) == R_GENERIC_IRELATIVE) {
|
|
return *reinterpret_cast<ElfW(Addr)*>(reloc_addr);
|
|
}
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
template<typename ElfRelT>
|
|
bool soinfo::relocate(ElfRelT* rel, unsigned count, const soinfo_list_t& global_group, const soinfo_list_t& local_group) {
|
|
for (size_t idx = 0; idx < count; ++idx, ++rel) {
|
|
ElfW(Word) type = ELFW(R_TYPE)(rel->r_info);
|
|
ElfW(Word) sym = ELFW(R_SYM)(rel->r_info);
|
|
|
|
ElfW(Addr) reloc = static_cast<ElfW(Addr)>(rel->r_offset + load_bias);
|
|
ElfW(Addr) sym_addr = 0;
|
|
const char* sym_name = nullptr;
|
|
ElfW(Addr) addend = get_addend(rel, reloc);
|
|
|
|
DEBUG("Processing '%s' relocation at index %zd", this->name, idx);
|
|
if (type == R_GENERIC_NONE) {
|
|
continue;
|
|
}
|
|
|
|
ElfW(Sym)* s = nullptr;
|
|
soinfo* lsi = nullptr;
|
|
|
|
if (sym != 0) {
|
|
sym_name = get_string(symtab_[sym].st_name);
|
|
s = soinfo_do_lookup(this, sym_name, &lsi, global_group,local_group);
|
|
if (s == nullptr) {
|
|
// We only allow an undefined symbol if this is a weak reference...
|
|
s = &symtab_[sym];
|
|
if (ELF_ST_BIND(s->st_info) != STB_WEAK) {
|
|
DL_ERR("cannot locate symbol \"%s\" referenced by \"%s\"...", sym_name, name);
|
|
return false;
|
|
}
|
|
|
|
/* IHI0044C AAELF 4.5.1.1:
|
|
|
|
Libraries are not searched to resolve weak references.
|
|
It is not an error for a weak reference to remain unsatisfied.
|
|
|
|
During linking, the value of an undefined weak reference is:
|
|
- Zero if the relocation type is absolute
|
|
- The address of the place if the relocation is pc-relative
|
|
- The address of nominal base address if the relocation
|
|
type is base-relative.
|
|
*/
|
|
|
|
switch (type) {
|
|
case R_GENERIC_JUMP_SLOT:
|
|
case R_GENERIC_GLOB_DAT:
|
|
case R_GENERIC_RELATIVE:
|
|
case R_GENERIC_IRELATIVE:
|
|
#if defined(__aarch64__)
|
|
case R_AARCH64_ABS64:
|
|
case R_AARCH64_ABS32:
|
|
case R_AARCH64_ABS16:
|
|
#elif defined(__x86_64__)
|
|
case R_X86_64_32:
|
|
case R_X86_64_64:
|
|
#elif defined(__arm__)
|
|
case R_ARM_ABS32:
|
|
#elif defined(__i386__)
|
|
case R_386_32:
|
|
#endif
|
|
/*
|
|
* The sym_addr was initialized to be zero above, or the relocation
|
|
* code below does not care about value of sym_addr.
|
|
* No need to do anything.
|
|
*/
|
|
break;
|
|
#if defined(__x86_64__)
|
|
case R_X86_64_PC32:
|
|
sym_addr = reloc;
|
|
break;
|
|
#elif defined(__i386__)
|
|
case R_386_PC32:
|
|
sym_addr = reloc;
|
|
break;
|
|
#endif
|
|
default:
|
|
DL_ERR("unknown weak reloc type %d @ %p (%zu)", type, rel, idx);
|
|
return false;
|
|
}
|
|
} else {
|
|
// We got a definition.
|
|
sym_addr = lsi->resolve_symbol_address(s);
|
|
}
|
|
count_relocation(kRelocSymbol);
|
|
}
|
|
|
|
switch (type) {
|
|
case R_GENERIC_JUMP_SLOT:
|
|
count_relocation(kRelocAbsolute);
|
|
MARK(rel->r_offset);
|
|
TRACE_TYPE(RELO, "RELO JMP_SLOT %16p <- %16p %s\n",
|
|
reinterpret_cast<void*>(reloc),
|
|
reinterpret_cast<void*>(sym_addr + addend), sym_name);
|
|
|
|
*reinterpret_cast<ElfW(Addr)*>(reloc) = (sym_addr + addend);
|
|
break;
|
|
case R_GENERIC_GLOB_DAT:
|
|
count_relocation(kRelocAbsolute);
|
|
MARK(rel->r_offset);
|
|
TRACE_TYPE(RELO, "RELO GLOB_DAT %16p <- %16p %s\n",
|
|
reinterpret_cast<void*>(reloc),
|
|
reinterpret_cast<void*>(sym_addr + addend), sym_name);
|
|
*reinterpret_cast<ElfW(Addr)*>(reloc) = (sym_addr + addend);
|
|
break;
|
|
case R_GENERIC_RELATIVE:
|
|
count_relocation(kRelocRelative);
|
|
MARK(rel->r_offset);
|
|
TRACE_TYPE(RELO, "RELO RELATIVE %16p <- %16p\n",
|
|
reinterpret_cast<void*>(reloc),
|
|
reinterpret_cast<void*>(base + addend));
|
|
*reinterpret_cast<ElfW(Addr)*>(reloc) = (base + addend);
|
|
break;
|
|
case R_GENERIC_IRELATIVE:
|
|
count_relocation(kRelocRelative);
|
|
MARK(rel->r_offset);
|
|
TRACE_TYPE(RELO, "RELO IRELATIVE %16p <- %16p\n",
|
|
reinterpret_cast<void*>(reloc),
|
|
reinterpret_cast<void*>(base + addend));
|
|
*reinterpret_cast<ElfW(Addr)*>(reloc) = call_ifunc_resolver(base + addend);
|
|
break;
|
|
|
|
#if defined(__aarch64__)
|
|
case R_AARCH64_ABS64:
|
|
count_relocation(kRelocAbsolute);
|
|
MARK(rel->r_offset);
|
|
TRACE_TYPE(RELO, "RELO ABS64 %16llx <- %16llx %s\n",
|
|
reloc, (sym_addr + addend), sym_name);
|
|
*reinterpret_cast<ElfW(Addr)*>(reloc) += (sym_addr + addend);
|
|
break;
|
|
case R_AARCH64_ABS32:
|
|
count_relocation(kRelocAbsolute);
|
|
MARK(rel->r_offset);
|
|
TRACE_TYPE(RELO, "RELO ABS32 %16llx <- %16llx %s\n",
|
|
reloc, (sym_addr + addend), sym_name);
|
|
if ((static_cast<ElfW(Addr)>(INT32_MIN) <= (*reinterpret_cast<ElfW(Addr)*>(reloc) + (sym_addr + addend))) &&
|
|
((*reinterpret_cast<ElfW(Addr)*>(reloc) + (sym_addr + addend)) <= static_cast<ElfW(Addr)>(UINT32_MAX))) {
|
|
*reinterpret_cast<ElfW(Addr)*>(reloc) += (sym_addr + addend);
|
|
} else {
|
|
DL_ERR("0x%016llx out of range 0x%016llx to 0x%016llx",
|
|
(*reinterpret_cast<ElfW(Addr)*>(reloc) + (sym_addr + addend)),
|
|
static_cast<ElfW(Addr)>(INT32_MIN),
|
|
static_cast<ElfW(Addr)>(UINT32_MAX));
|
|
return false;
|
|
}
|
|
break;
|
|
case R_AARCH64_ABS16:
|
|
count_relocation(kRelocAbsolute);
|
|
MARK(rel->r_offset);
|
|
TRACE_TYPE(RELO, "RELO ABS16 %16llx <- %16llx %s\n",
|
|
reloc, (sym_addr + addend), sym_name);
|
|
if ((static_cast<ElfW(Addr)>(INT16_MIN) <= (*reinterpret_cast<ElfW(Addr)*>(reloc) + (sym_addr + addend))) &&
|
|
((*reinterpret_cast<ElfW(Addr)*>(reloc) + (sym_addr + addend)) <= static_cast<ElfW(Addr)>(UINT16_MAX))) {
|
|
*reinterpret_cast<ElfW(Addr)*>(reloc) += (sym_addr + addend);
|
|
} else {
|
|
DL_ERR("0x%016llx out of range 0x%016llx to 0x%016llx",
|
|
(*reinterpret_cast<ElfW(Addr)*>(reloc) + (sym_addr + addend)),
|
|
static_cast<ElfW(Addr)>(INT16_MIN),
|
|
static_cast<ElfW(Addr)>(UINT16_MAX));
|
|
return false;
|
|
}
|
|
break;
|
|
case R_AARCH64_PREL64:
|
|
count_relocation(kRelocRelative);
|
|
MARK(rel->r_offset);
|
|
TRACE_TYPE(RELO, "RELO REL64 %16llx <- %16llx - %16llx %s\n",
|
|
reloc, (sym_addr + addend), rel->r_offset, sym_name);
|
|
*reinterpret_cast<ElfW(Addr)*>(reloc) += (sym_addr + addend) - rel->r_offset;
|
|
break;
|
|
case R_AARCH64_PREL32:
|
|
count_relocation(kRelocRelative);
|
|
MARK(rel->r_offset);
|
|
TRACE_TYPE(RELO, "RELO REL32 %16llx <- %16llx - %16llx %s\n",
|
|
reloc, (sym_addr + addend), rel->r_offset, sym_name);
|
|
if ((static_cast<ElfW(Addr)>(INT32_MIN) <= (*reinterpret_cast<ElfW(Addr)*>(reloc) + ((sym_addr + addend) - rel->r_offset))) &&
|
|
((*reinterpret_cast<ElfW(Addr)*>(reloc) + ((sym_addr + addend) - rel->r_offset)) <= static_cast<ElfW(Addr)>(UINT32_MAX))) {
|
|
*reinterpret_cast<ElfW(Addr)*>(reloc) += ((sym_addr + addend) - rel->r_offset);
|
|
} else {
|
|
DL_ERR("0x%016llx out of range 0x%016llx to 0x%016llx",
|
|
(*reinterpret_cast<ElfW(Addr)*>(reloc) + ((sym_addr + addend) - rel->r_offset)),
|
|
static_cast<ElfW(Addr)>(INT32_MIN),
|
|
static_cast<ElfW(Addr)>(UINT32_MAX));
|
|
return false;
|
|
}
|
|
break;
|
|
case R_AARCH64_PREL16:
|
|
count_relocation(kRelocRelative);
|
|
MARK(rel->r_offset);
|
|
TRACE_TYPE(RELO, "RELO REL16 %16llx <- %16llx - %16llx %s\n",
|
|
reloc, (sym_addr + addend), rel->r_offset, sym_name);
|
|
if ((static_cast<ElfW(Addr)>(INT16_MIN) <= (*reinterpret_cast<ElfW(Addr)*>(reloc) + ((sym_addr + addend) - rel->r_offset))) &&
|
|
((*reinterpret_cast<ElfW(Addr)*>(reloc) + ((sym_addr + addend) - rel->r_offset)) <= static_cast<ElfW(Addr)>(UINT16_MAX))) {
|
|
*reinterpret_cast<ElfW(Addr)*>(reloc) += ((sym_addr + addend) - rel->r_offset);
|
|
} else {
|
|
DL_ERR("0x%016llx out of range 0x%016llx to 0x%016llx",
|
|
(*reinterpret_cast<ElfW(Addr)*>(reloc) + ((sym_addr + addend) - rel->r_offset)),
|
|
static_cast<ElfW(Addr)>(INT16_MIN),
|
|
static_cast<ElfW(Addr)>(UINT16_MAX));
|
|
return false;
|
|
}
|
|
break;
|
|
|
|
case R_AARCH64_COPY:
|
|
/*
|
|
* ET_EXEC is not supported so this should not happen.
|
|
*
|
|
* http://infocenter.arm.com/help/topic/com.arm.doc.ihi0044d/IHI0044D_aaelf.pdf
|
|
*
|
|
* Section 4.7.1.10 "Dynamic relocations"
|
|
* R_AARCH64_COPY may only appear in executable objects where e_type is
|
|
* set to ET_EXEC.
|
|
*/
|
|
DL_ERR("%s R_AARCH64_COPY relocations are not supported", name);
|
|
return false;
|
|
case R_AARCH64_TLS_TPREL64:
|
|
TRACE_TYPE(RELO, "RELO TLS_TPREL64 *** %16llx <- %16llx - %16llx\n",
|
|
reloc, (sym_addr + addend), rel->r_offset);
|
|
break;
|
|
case R_AARCH64_TLS_DTPREL32:
|
|
TRACE_TYPE(RELO, "RELO TLS_DTPREL32 *** %16llx <- %16llx - %16llx\n",
|
|
reloc, (sym_addr + addend), rel->r_offset);
|
|
break;
|
|
#elif defined(__x86_64__)
|
|
case R_X86_64_32:
|
|
count_relocation(kRelocRelative);
|
|
MARK(rel->r_offset);
|
|
TRACE_TYPE(RELO, "RELO R_X86_64_32 %08zx <- +%08zx %s", static_cast<size_t>(reloc),
|
|
static_cast<size_t>(sym_addr), sym_name);
|
|
*reinterpret_cast<ElfW(Addr)*>(reloc) = sym_addr + addend;
|
|
break;
|
|
case R_X86_64_64:
|
|
count_relocation(kRelocRelative);
|
|
MARK(rel->r_offset);
|
|
TRACE_TYPE(RELO, "RELO R_X86_64_64 %08zx <- +%08zx %s", static_cast<size_t>(reloc),
|
|
static_cast<size_t>(sym_addr), sym_name);
|
|
*reinterpret_cast<ElfW(Addr)*>(reloc) = sym_addr + addend;
|
|
break;
|
|
case R_X86_64_PC32:
|
|
count_relocation(kRelocRelative);
|
|
MARK(rel->r_offset);
|
|
TRACE_TYPE(RELO, "RELO R_X86_64_PC32 %08zx <- +%08zx (%08zx - %08zx) %s",
|
|
static_cast<size_t>(reloc), static_cast<size_t>(sym_addr - reloc),
|
|
static_cast<size_t>(sym_addr), static_cast<size_t>(reloc), sym_name);
|
|
*reinterpret_cast<ElfW(Addr)*>(reloc) = sym_addr + addend - reloc;
|
|
break;
|
|
#elif defined(__arm__)
|
|
case R_ARM_ABS32:
|
|
count_relocation(kRelocAbsolute);
|
|
MARK(rel->r_offset);
|
|
TRACE_TYPE(RELO, "RELO ABS %08x <- %08x %s", reloc, sym_addr, sym_name);
|
|
*reinterpret_cast<ElfW(Addr)*>(reloc) += sym_addr;
|
|
break;
|
|
case R_ARM_REL32:
|
|
count_relocation(kRelocRelative);
|
|
MARK(rel->r_offset);
|
|
TRACE_TYPE(RELO, "RELO REL32 %08x <- %08x - %08x %s",
|
|
reloc, sym_addr, rel->r_offset, sym_name);
|
|
*reinterpret_cast<ElfW(Addr)*>(reloc) += sym_addr - rel->r_offset;
|
|
break;
|
|
case R_ARM_COPY:
|
|
/*
|
|
* ET_EXEC is not supported so this should not happen.
|
|
*
|
|
* http://infocenter.arm.com/help/topic/com.arm.doc.ihi0044d/IHI0044D_aaelf.pdf
|
|
*
|
|
* Section 4.7.1.10 "Dynamic relocations"
|
|
* R_ARM_COPY may only appear in executable objects where e_type is
|
|
* set to ET_EXEC.
|
|
*/
|
|
DL_ERR("%s R_ARM_COPY relocations are not supported", name);
|
|
return false;
|
|
#elif defined(__i386__)
|
|
case R_386_32:
|
|
count_relocation(kRelocRelative);
|
|
MARK(rel->r_offset);
|
|
TRACE_TYPE(RELO, "RELO R_386_32 %08x <- +%08x %s", reloc, sym_addr, sym_name);
|
|
*reinterpret_cast<ElfW(Addr)*>(reloc) += sym_addr;
|
|
break;
|
|
case R_386_PC32:
|
|
count_relocation(kRelocRelative);
|
|
MARK(rel->r_offset);
|
|
TRACE_TYPE(RELO, "RELO R_386_PC32 %08x <- +%08x (%08x - %08x) %s",
|
|
reloc, (sym_addr - reloc), sym_addr, reloc, sym_name);
|
|
*reinterpret_cast<ElfW(Addr)*>(reloc) += (sym_addr - reloc);
|
|
break;
|
|
#endif
|
|
default:
|
|
DL_ERR("unknown reloc type %d @ %p (%zu)", type, rel, idx);
|
|
return false;
|
|
}
|
|
}
|
|
return true;
|
|
}
|
|
#endif // !defined(__mips__)
|
|
|
|
void soinfo::call_array(const char* array_name __unused, linker_function_t* functions, size_t count, bool reverse) {
|
|
if (functions == nullptr) {
|
|
return;
|
|
}
|
|
|
|
TRACE("[ Calling %s (size %zd) @ %p for '%s' ]", array_name, count, functions, name);
|
|
|
|
int begin = reverse ? (count - 1) : 0;
|
|
int end = reverse ? -1 : count;
|
|
int step = reverse ? -1 : 1;
|
|
|
|
for (int i = begin; i != end; i += step) {
|
|
TRACE("[ %s[%d] == %p ]", array_name, i, functions[i]);
|
|
call_function("function", functions[i]);
|
|
}
|
|
|
|
TRACE("[ Done calling %s for '%s' ]", array_name, name);
|
|
}
|
|
|
|
void soinfo::call_function(const char* function_name __unused, linker_function_t function) {
|
|
if (function == nullptr || reinterpret_cast<uintptr_t>(function) == static_cast<uintptr_t>(-1)) {
|
|
return;
|
|
}
|
|
|
|
TRACE("[ Calling %s @ %p for '%s' ]", function_name, function, name);
|
|
function();
|
|
TRACE("[ Done calling %s @ %p for '%s' ]", function_name, function, name);
|
|
}
|
|
|
|
void soinfo::call_pre_init_constructors() {
|
|
// DT_PREINIT_ARRAY functions are called before any other constructors for executables,
|
|
// but ignored in a shared library.
|
|
call_array("DT_PREINIT_ARRAY", preinit_array_, preinit_array_count_, false);
|
|
}
|
|
|
|
void soinfo::call_constructors() {
|
|
if (constructors_called) {
|
|
return;
|
|
}
|
|
|
|
// We set constructors_called before actually calling the constructors, otherwise it doesn't
|
|
// protect against recursive constructor calls. One simple example of constructor recursion
|
|
// is the libc debug malloc, which is implemented in libc_malloc_debug_leak.so:
|
|
// 1. The program depends on libc, so libc's constructor is called here.
|
|
// 2. The libc constructor calls dlopen() to load libc_malloc_debug_leak.so.
|
|
// 3. dlopen() calls the constructors on the newly created
|
|
// soinfo for libc_malloc_debug_leak.so.
|
|
// 4. The debug .so depends on libc, so CallConstructors is
|
|
// called again with the libc soinfo. If it doesn't trigger the early-
|
|
// out above, the libc constructor will be called again (recursively!).
|
|
constructors_called = true;
|
|
|
|
if (!is_main_executable() && preinit_array_ != nullptr) {
|
|
// The GNU dynamic linker silently ignores these, but we warn the developer.
|
|
PRINT("\"%s\": ignoring %zd-entry DT_PREINIT_ARRAY in shared library!",
|
|
name, preinit_array_count_);
|
|
}
|
|
|
|
get_children().for_each([] (soinfo* si) {
|
|
si->call_constructors();
|
|
});
|
|
|
|
TRACE("\"%s\": calling constructors", name);
|
|
|
|
// DT_INIT should be called before DT_INIT_ARRAY if both are present.
|
|
call_function("DT_INIT", init_func_);
|
|
call_array("DT_INIT_ARRAY", init_array_, init_array_count_, false);
|
|
}
|
|
|
|
void soinfo::call_destructors() {
|
|
if (!constructors_called) {
|
|
return;
|
|
}
|
|
TRACE("\"%s\": calling destructors", name);
|
|
|
|
// DT_FINI_ARRAY must be parsed in reverse order.
|
|
call_array("DT_FINI_ARRAY", fini_array_, fini_array_count_, true);
|
|
|
|
// DT_FINI should be called after DT_FINI_ARRAY if both are present.
|
|
call_function("DT_FINI", fini_func_);
|
|
|
|
// This is needed on second call to dlopen
|
|
// after library has been unloaded with RTLD_NODELETE
|
|
constructors_called = false;
|
|
}
|
|
|
|
void soinfo::add_child(soinfo* child) {
|
|
if (has_min_version(0)) {
|
|
child->parents_.push_back(this);
|
|
this->children_.push_back(child);
|
|
}
|
|
}
|
|
|
|
void soinfo::remove_all_links() {
|
|
if (!has_min_version(0)) {
|
|
return;
|
|
}
|
|
|
|
// 1. Untie connected soinfos from 'this'.
|
|
children_.for_each([&] (soinfo* child) {
|
|
child->parents_.remove_if([&] (const soinfo* parent) {
|
|
return parent == this;
|
|
});
|
|
});
|
|
|
|
parents_.for_each([&] (soinfo* parent) {
|
|
parent->children_.remove_if([&] (const soinfo* child) {
|
|
return child == this;
|
|
});
|
|
});
|
|
|
|
// 2. Once everything untied - clear local lists.
|
|
parents_.clear();
|
|
children_.clear();
|
|
}
|
|
|
|
dev_t soinfo::get_st_dev() const {
|
|
if (has_min_version(0)) {
|
|
return st_dev_;
|
|
}
|
|
|
|
return 0;
|
|
};
|
|
|
|
ino_t soinfo::get_st_ino() const {
|
|
if (has_min_version(0)) {
|
|
return st_ino_;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
off64_t soinfo::get_file_offset() const {
|
|
if (has_min_version(1)) {
|
|
return file_offset_;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
uint32_t soinfo::get_rtld_flags() const {
|
|
if (has_min_version(1)) {
|
|
return rtld_flags_;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
uint32_t soinfo::get_dt_flags_1() const {
|
|
if (has_min_version(1)) {
|
|
return dt_flags_1_;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
void soinfo::set_dt_flags_1(uint32_t dt_flags_1) {
|
|
if (has_min_version(1)) {
|
|
if ((dt_flags_1 & DF_1_GLOBAL) != 0) {
|
|
rtld_flags_ |= RTLD_GLOBAL;
|
|
}
|
|
|
|
if ((dt_flags_1 & DF_1_NODELETE) != 0) {
|
|
rtld_flags_ |= RTLD_NODELETE;
|
|
}
|
|
|
|
dt_flags_1_ = dt_flags_1;
|
|
}
|
|
}
|
|
|
|
// This is a return on get_children()/get_parents() if
|
|
// 'this->flags' does not have FLAG_NEW_SOINFO set.
|
|
static soinfo::soinfo_list_t g_empty_list;
|
|
|
|
soinfo::soinfo_list_t& soinfo::get_children() {
|
|
if (has_min_version(0)) {
|
|
return children_;
|
|
}
|
|
|
|
return g_empty_list;
|
|
}
|
|
|
|
soinfo::soinfo_list_t& soinfo::get_parents() {
|
|
if (has_min_version(0)) {
|
|
return parents_;
|
|
}
|
|
|
|
return g_empty_list;
|
|
}
|
|
|
|
ElfW(Addr) soinfo::resolve_symbol_address(ElfW(Sym)* s) {
|
|
if (ELF_ST_TYPE(s->st_info) == STT_GNU_IFUNC) {
|
|
return call_ifunc_resolver(s->st_value + load_bias);
|
|
}
|
|
|
|
return static_cast<ElfW(Addr)>(s->st_value + load_bias);
|
|
}
|
|
|
|
const char* soinfo::get_string(ElfW(Word) index) const {
|
|
if (has_min_version(1) && (index >= strtab_size_)) {
|
|
__libc_fatal("%s: strtab out of bounds error; STRSZ=%zd, name=%d", name, strtab_size_, index);
|
|
}
|
|
|
|
return strtab_ + index;
|
|
}
|
|
|
|
bool soinfo::is_gnu_hash() const {
|
|
return (flags_ & FLAG_GNU_HASH) != 0;
|
|
}
|
|
|
|
bool soinfo::can_unload() const {
|
|
return (get_rtld_flags() & (RTLD_NODELETE | RTLD_GLOBAL)) == 0;
|
|
}
|
|
|
|
bool soinfo::is_linked() const {
|
|
return (flags_ & FLAG_LINKED) != 0;
|
|
}
|
|
|
|
bool soinfo::is_main_executable() const {
|
|
return (flags_ & FLAG_EXE) != 0;
|
|
}
|
|
|
|
void soinfo::set_linked() {
|
|
flags_ |= FLAG_LINKED;
|
|
}
|
|
|
|
void soinfo::set_linker_flag() {
|
|
flags_ |= FLAG_LINKER;
|
|
}
|
|
|
|
void soinfo::set_main_executable() {
|
|
flags_ |= FLAG_EXE;
|
|
}
|
|
|
|
void soinfo::increment_ref_count() {
|
|
local_group_root_->ref_count_++;
|
|
}
|
|
|
|
size_t soinfo::decrement_ref_count() {
|
|
return --local_group_root_->ref_count_;
|
|
}
|
|
|
|
soinfo* soinfo::get_local_group_root() const {
|
|
return local_group_root_;
|
|
}
|
|
|
|
/* Force any of the closed stdin, stdout and stderr to be associated with
|
|
/dev/null. */
|
|
static int nullify_closed_stdio() {
|
|
int dev_null, i, status;
|
|
int return_value = 0;
|
|
|
|
dev_null = TEMP_FAILURE_RETRY(open("/dev/null", O_RDWR));
|
|
if (dev_null < 0) {
|
|
DL_ERR("cannot open /dev/null: %s", strerror(errno));
|
|
return -1;
|
|
}
|
|
TRACE("[ Opened /dev/null file-descriptor=%d]", dev_null);
|
|
|
|
/* If any of the stdio file descriptors is valid and not associated
|
|
with /dev/null, dup /dev/null to it. */
|
|
for (i = 0; i < 3; i++) {
|
|
/* If it is /dev/null already, we are done. */
|
|
if (i == dev_null) {
|
|
continue;
|
|
}
|
|
|
|
TRACE("[ Nullifying stdio file descriptor %d]", i);
|
|
status = TEMP_FAILURE_RETRY(fcntl(i, F_GETFL));
|
|
|
|
/* If file is opened, we are good. */
|
|
if (status != -1) {
|
|
continue;
|
|
}
|
|
|
|
/* The only error we allow is that the file descriptor does not
|
|
exist, in which case we dup /dev/null to it. */
|
|
if (errno != EBADF) {
|
|
DL_ERR("fcntl failed: %s", strerror(errno));
|
|
return_value = -1;
|
|
continue;
|
|
}
|
|
|
|
/* Try dupping /dev/null to this stdio file descriptor and
|
|
repeat if there is a signal. Note that any errors in closing
|
|
the stdio descriptor are lost. */
|
|
status = TEMP_FAILURE_RETRY(dup2(dev_null, i));
|
|
if (status < 0) {
|
|
DL_ERR("dup2 failed: %s", strerror(errno));
|
|
return_value = -1;
|
|
continue;
|
|
}
|
|
}
|
|
|
|
/* If /dev/null is not one of the stdio file descriptors, close it. */
|
|
if (dev_null > 2) {
|
|
TRACE("[ Closing /dev/null file-descriptor=%d]", dev_null);
|
|
status = TEMP_FAILURE_RETRY(close(dev_null));
|
|
if (status == -1) {
|
|
DL_ERR("close failed: %s", strerror(errno));
|
|
return_value = -1;
|
|
}
|
|
}
|
|
|
|
return return_value;
|
|
}
|
|
|
|
bool soinfo::prelink_image() {
|
|
/* Extract dynamic section */
|
|
ElfW(Word) dynamic_flags = 0;
|
|
phdr_table_get_dynamic_section(phdr, phnum, load_bias, &dynamic, &dynamic_flags);
|
|
|
|
/* We can't log anything until the linker is relocated */
|
|
bool relocating_linker = (flags_ & FLAG_LINKER) != 0;
|
|
if (!relocating_linker) {
|
|
INFO("[ linking %s ]", name);
|
|
DEBUG("si->base = %p si->flags = 0x%08x", reinterpret_cast<void*>(base), flags_);
|
|
}
|
|
|
|
if (dynamic == nullptr) {
|
|
if (!relocating_linker) {
|
|
DL_ERR("missing PT_DYNAMIC in \"%s\"", name);
|
|
}
|
|
return false;
|
|
} else {
|
|
if (!relocating_linker) {
|
|
DEBUG("dynamic = %p", dynamic);
|
|
}
|
|
}
|
|
|
|
#if defined(__arm__)
|
|
(void) phdr_table_get_arm_exidx(phdr, phnum, load_bias,
|
|
&ARM_exidx, &ARM_exidx_count);
|
|
#endif
|
|
|
|
// Extract useful information from dynamic section.
|
|
uint32_t needed_count = 0;
|
|
for (ElfW(Dyn)* d = dynamic; d->d_tag != DT_NULL; ++d) {
|
|
DEBUG("d = %p, d[0](tag) = %p d[1](val) = %p",
|
|
d, reinterpret_cast<void*>(d->d_tag), reinterpret_cast<void*>(d->d_un.d_val));
|
|
switch (d->d_tag) {
|
|
case DT_SONAME:
|
|
// TODO: glibc dynamic linker uses this name for
|
|
// initial library lookup; consider doing the same here.
|
|
break;
|
|
|
|
case DT_HASH:
|
|
if (nbucket_ != 0) {
|
|
// in case of --hash-style=both, we prefer gnu
|
|
break;
|
|
}
|
|
|
|
nbucket_ = reinterpret_cast<uint32_t*>(load_bias + d->d_un.d_ptr)[0];
|
|
nchain_ = reinterpret_cast<uint32_t*>(load_bias + d->d_un.d_ptr)[1];
|
|
bucket_ = reinterpret_cast<uint32_t*>(load_bias + d->d_un.d_ptr + 8);
|
|
chain_ = reinterpret_cast<uint32_t*>(load_bias + d->d_un.d_ptr + 8 + nbucket_ * 4);
|
|
break;
|
|
|
|
case DT_GNU_HASH:
|
|
if (nbucket_ != 0) {
|
|
// in case of --hash-style=both, we prefer gnu
|
|
nchain_ = 0;
|
|
}
|
|
|
|
nbucket_ = reinterpret_cast<uint32_t*>(load_bias + d->d_un.d_ptr)[0];
|
|
// skip symndx
|
|
gnu_maskwords_ = reinterpret_cast<uint32_t*>(load_bias + d->d_un.d_ptr)[2];
|
|
gnu_shift2_ = reinterpret_cast<uint32_t*>(load_bias + d->d_un.d_ptr)[3];
|
|
|
|
gnu_bloom_filter_ = reinterpret_cast<ElfW(Addr)*>(load_bias + d->d_un.d_ptr + 16);
|
|
bucket_ = reinterpret_cast<uint32_t*>(gnu_bloom_filter_ + gnu_maskwords_);
|
|
// amend chain for symndx = header[1]
|
|
chain_ = bucket_ + nbucket_ - reinterpret_cast<uint32_t*>(load_bias + d->d_un.d_ptr)[1];
|
|
|
|
if (!powerof2(gnu_maskwords_)) {
|
|
DL_ERR("invalid maskwords for gnu_hash = 0x%x, in \"%s\" expecting power to two", gnu_maskwords_, name);
|
|
return false;
|
|
}
|
|
--gnu_maskwords_;
|
|
|
|
flags_ |= FLAG_GNU_HASH;
|
|
break;
|
|
|
|
case DT_STRTAB:
|
|
strtab_ = reinterpret_cast<const char*>(load_bias + d->d_un.d_ptr);
|
|
break;
|
|
|
|
case DT_STRSZ:
|
|
strtab_size_ = d->d_un.d_val;
|
|
break;
|
|
|
|
case DT_SYMTAB:
|
|
symtab_ = reinterpret_cast<ElfW(Sym)*>(load_bias + d->d_un.d_ptr);
|
|
break;
|
|
|
|
case DT_SYMENT:
|
|
if (d->d_un.d_val != sizeof(ElfW(Sym))) {
|
|
DL_ERR("invalid DT_SYMENT: %zd in \"%s\"", static_cast<size_t>(d->d_un.d_val), name);
|
|
return false;
|
|
}
|
|
break;
|
|
|
|
case DT_PLTREL:
|
|
#if defined(USE_RELA)
|
|
if (d->d_un.d_val != DT_RELA) {
|
|
DL_ERR("unsupported DT_PLTREL in \"%s\"; expected DT_RELA", name);
|
|
return false;
|
|
}
|
|
#else
|
|
if (d->d_un.d_val != DT_REL) {
|
|
DL_ERR("unsupported DT_PLTREL in \"%s\"; expected DT_REL", name);
|
|
return false;
|
|
}
|
|
#endif
|
|
break;
|
|
|
|
case DT_JMPREL:
|
|
#if defined(USE_RELA)
|
|
plt_rela_ = reinterpret_cast<ElfW(Rela)*>(load_bias + d->d_un.d_ptr);
|
|
#else
|
|
plt_rel_ = reinterpret_cast<ElfW(Rel)*>(load_bias + d->d_un.d_ptr);
|
|
#endif
|
|
break;
|
|
|
|
case DT_PLTRELSZ:
|
|
#if defined(USE_RELA)
|
|
plt_rela_count_ = d->d_un.d_val / sizeof(ElfW(Rela));
|
|
#else
|
|
plt_rel_count_ = d->d_un.d_val / sizeof(ElfW(Rel));
|
|
#endif
|
|
break;
|
|
|
|
case DT_PLTGOT:
|
|
#if defined(__mips__)
|
|
// Used by mips and mips64.
|
|
plt_got_ = reinterpret_cast<ElfW(Addr)**>(load_bias + d->d_un.d_ptr);
|
|
#endif
|
|
// Ignore for other platforms... (because RTLD_LAZY is not supported)
|
|
break;
|
|
|
|
case DT_DEBUG:
|
|
// Set the DT_DEBUG entry to the address of _r_debug for GDB
|
|
// if the dynamic table is writable
|
|
// FIXME: not working currently for N64
|
|
// The flags for the LOAD and DYNAMIC program headers do not agree.
|
|
// The LOAD section containing the dynamic table has been mapped as
|
|
// read-only, but the DYNAMIC header claims it is writable.
|
|
#if !(defined(__mips__) && defined(__LP64__))
|
|
if ((dynamic_flags & PF_W) != 0) {
|
|
d->d_un.d_val = reinterpret_cast<uintptr_t>(&_r_debug);
|
|
}
|
|
break;
|
|
#endif
|
|
#if defined(USE_RELA)
|
|
case DT_RELA:
|
|
rela_ = reinterpret_cast<ElfW(Rela)*>(load_bias + d->d_un.d_ptr);
|
|
break;
|
|
|
|
case DT_RELASZ:
|
|
rela_count_ = d->d_un.d_val / sizeof(ElfW(Rela));
|
|
break;
|
|
|
|
case DT_RELAENT:
|
|
if (d->d_un.d_val != sizeof(ElfW(Rela))) {
|
|
DL_ERR("invalid DT_RELAENT: %zd", static_cast<size_t>(d->d_un.d_val));
|
|
return false;
|
|
}
|
|
break;
|
|
|
|
// ignored (see DT_RELCOUNT comments for details)
|
|
case DT_RELACOUNT:
|
|
break;
|
|
|
|
case DT_REL:
|
|
DL_ERR("unsupported DT_REL in \"%s\"", name);
|
|
return false;
|
|
|
|
case DT_RELSZ:
|
|
DL_ERR("unsupported DT_RELSZ in \"%s\"", name);
|
|
return false;
|
|
#else
|
|
case DT_REL:
|
|
rel_ = reinterpret_cast<ElfW(Rel)*>(load_bias + d->d_un.d_ptr);
|
|
break;
|
|
|
|
case DT_RELSZ:
|
|
rel_count_ = d->d_un.d_val / sizeof(ElfW(Rel));
|
|
break;
|
|
|
|
case DT_RELENT:
|
|
if (d->d_un.d_val != sizeof(ElfW(Rel))) {
|
|
DL_ERR("invalid DT_RELENT: %zd", static_cast<size_t>(d->d_un.d_val));
|
|
return false;
|
|
}
|
|
break;
|
|
|
|
// "Indicates that all RELATIVE relocations have been concatenated together,
|
|
// and specifies the RELATIVE relocation count."
|
|
//
|
|
// TODO: Spec also mentions that this can be used to optimize relocation process;
|
|
// Not currently used by bionic linker - ignored.
|
|
case DT_RELCOUNT:
|
|
break;
|
|
case DT_RELA:
|
|
DL_ERR("unsupported DT_RELA in \"%s\"", name);
|
|
return false;
|
|
#endif
|
|
case DT_INIT:
|
|
init_func_ = reinterpret_cast<linker_function_t>(load_bias + d->d_un.d_ptr);
|
|
DEBUG("%s constructors (DT_INIT) found at %p", name, init_func_);
|
|
break;
|
|
|
|
case DT_FINI:
|
|
fini_func_ = reinterpret_cast<linker_function_t>(load_bias + d->d_un.d_ptr);
|
|
DEBUG("%s destructors (DT_FINI) found at %p", name, fini_func_);
|
|
break;
|
|
|
|
case DT_INIT_ARRAY:
|
|
init_array_ = reinterpret_cast<linker_function_t*>(load_bias + d->d_un.d_ptr);
|
|
DEBUG("%s constructors (DT_INIT_ARRAY) found at %p", name, init_array_);
|
|
break;
|
|
|
|
case DT_INIT_ARRAYSZ:
|
|
init_array_count_ = static_cast<uint32_t>(d->d_un.d_val) / sizeof(ElfW(Addr));
|
|
break;
|
|
|
|
case DT_FINI_ARRAY:
|
|
fini_array_ = reinterpret_cast<linker_function_t*>(load_bias + d->d_un.d_ptr);
|
|
DEBUG("%s destructors (DT_FINI_ARRAY) found at %p", name, fini_array_);
|
|
break;
|
|
|
|
case DT_FINI_ARRAYSZ:
|
|
fini_array_count_ = static_cast<uint32_t>(d->d_un.d_val) / sizeof(ElfW(Addr));
|
|
break;
|
|
|
|
case DT_PREINIT_ARRAY:
|
|
preinit_array_ = reinterpret_cast<linker_function_t*>(load_bias + d->d_un.d_ptr);
|
|
DEBUG("%s constructors (DT_PREINIT_ARRAY) found at %p", name, preinit_array_);
|
|
break;
|
|
|
|
case DT_PREINIT_ARRAYSZ:
|
|
preinit_array_count_ = static_cast<uint32_t>(d->d_un.d_val) / sizeof(ElfW(Addr));
|
|
break;
|
|
|
|
case DT_TEXTREL:
|
|
#if defined(__LP64__)
|
|
DL_ERR("text relocations (DT_TEXTREL) found in 64-bit ELF file \"%s\"", name);
|
|
return false;
|
|
#else
|
|
has_text_relocations = true;
|
|
break;
|
|
#endif
|
|
|
|
case DT_SYMBOLIC:
|
|
has_DT_SYMBOLIC = true;
|
|
break;
|
|
|
|
case DT_NEEDED:
|
|
++needed_count;
|
|
break;
|
|
|
|
case DT_FLAGS:
|
|
if (d->d_un.d_val & DF_TEXTREL) {
|
|
#if defined(__LP64__)
|
|
DL_ERR("text relocations (DF_TEXTREL) found in 64-bit ELF file \"%s\"", name);
|
|
return false;
|
|
#else
|
|
has_text_relocations = true;
|
|
#endif
|
|
}
|
|
if (d->d_un.d_val & DF_SYMBOLIC) {
|
|
has_DT_SYMBOLIC = true;
|
|
}
|
|
break;
|
|
|
|
case DT_FLAGS_1:
|
|
set_dt_flags_1(d->d_un.d_val);
|
|
|
|
if ((d->d_un.d_val & ~SUPPORTED_DT_FLAGS_1) != 0) {
|
|
DL_WARN("Unsupported flags DT_FLAGS_1=%p", reinterpret_cast<void*>(d->d_un.d_val));
|
|
}
|
|
break;
|
|
#if defined(__mips__)
|
|
case DT_MIPS_RLD_MAP:
|
|
// Set the DT_MIPS_RLD_MAP entry to the address of _r_debug for GDB.
|
|
{
|
|
r_debug** dp = reinterpret_cast<r_debug**>(load_bias + d->d_un.d_ptr);
|
|
*dp = &_r_debug;
|
|
}
|
|
break;
|
|
case DT_MIPS_RLD_MAP2:
|
|
// Set the DT_MIPS_RLD_MAP2 entry to the address of _r_debug for GDB.
|
|
{
|
|
r_debug** dp = reinterpret_cast<r_debug**>(reinterpret_cast<ElfW(Addr)>(d) + d->d_un.d_val);
|
|
*dp = &_r_debug;
|
|
}
|
|
break;
|
|
|
|
case DT_MIPS_RLD_VERSION:
|
|
case DT_MIPS_FLAGS:
|
|
case DT_MIPS_BASE_ADDRESS:
|
|
case DT_MIPS_UNREFEXTNO:
|
|
break;
|
|
|
|
case DT_MIPS_SYMTABNO:
|
|
mips_symtabno_ = d->d_un.d_val;
|
|
break;
|
|
|
|
case DT_MIPS_LOCAL_GOTNO:
|
|
mips_local_gotno_ = d->d_un.d_val;
|
|
break;
|
|
|
|
case DT_MIPS_GOTSYM:
|
|
mips_gotsym_ = d->d_un.d_val;
|
|
break;
|
|
#endif
|
|
// Ignored: "Its use has been superseded by the DF_BIND_NOW flag"
|
|
case DT_BIND_NOW:
|
|
break;
|
|
|
|
// Ignore: bionic does not support symbol versioning...
|
|
case DT_VERSYM:
|
|
case DT_VERDEF:
|
|
case DT_VERDEFNUM:
|
|
case DT_VERNEED:
|
|
case DT_VERNEEDNUM:
|
|
break;
|
|
|
|
default:
|
|
if (!relocating_linker) {
|
|
DL_WARN("%s: unused DT entry: type %p arg %p", name,
|
|
reinterpret_cast<void*>(d->d_tag), reinterpret_cast<void*>(d->d_un.d_val));
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
|
|
DEBUG("si->base = %p, si->strtab = %p, si->symtab = %p",
|
|
reinterpret_cast<void*>(base), strtab_, symtab_);
|
|
|
|
// Sanity checks.
|
|
if (relocating_linker && needed_count != 0) {
|
|
DL_ERR("linker cannot have DT_NEEDED dependencies on other libraries");
|
|
return false;
|
|
}
|
|
if (nbucket_ == 0) {
|
|
DL_ERR("empty/missing DT_HASH/DT_GNU_HASH in \"%s\" (new hash type from the future?)", name);
|
|
return false;
|
|
}
|
|
if (strtab_ == 0) {
|
|
DL_ERR("empty/missing DT_STRTAB in \"%s\"", name);
|
|
return false;
|
|
}
|
|
if (symtab_ == 0) {
|
|
DL_ERR("empty/missing DT_SYMTAB in \"%s\"", name);
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
bool soinfo::link_image(const soinfo_list_t& global_group, const soinfo_list_t& local_group, const android_dlextinfo* extinfo) {
|
|
|
|
local_group_root_ = local_group.front();
|
|
if (local_group_root_ == nullptr) {
|
|
local_group_root_ = this;
|
|
}
|
|
|
|
#if !defined(__LP64__)
|
|
if (has_text_relocations) {
|
|
// Make segments writable to allow text relocations to work properly. We will later call
|
|
// phdr_table_protect_segments() after all of them are applied and all constructors are run.
|
|
DL_WARN("%s has text relocations. This is wasting memory and prevents "
|
|
"security hardening. Please fix.", name);
|
|
if (phdr_table_unprotect_segments(phdr, phnum, load_bias) < 0) {
|
|
DL_ERR("can't unprotect loadable segments for \"%s\": %s",
|
|
name, strerror(errno));
|
|
return false;
|
|
}
|
|
}
|
|
#endif
|
|
|
|
#if defined(USE_RELA)
|
|
if (rela_ != nullptr) {
|
|
DEBUG("[ relocating %s ]", name);
|
|
if (!relocate(rela_, rela_count_, global_group, local_group)) {
|
|
return false;
|
|
}
|
|
}
|
|
if (plt_rela_ != nullptr) {
|
|
DEBUG("[ relocating %s plt ]", name);
|
|
if (!relocate(plt_rela_, plt_rela_count_, global_group, local_group)) {
|
|
return false;
|
|
}
|
|
}
|
|
#else
|
|
if (rel_ != nullptr) {
|
|
DEBUG("[ relocating %s ]", name);
|
|
if (!relocate(rel_, rel_count_, global_group, local_group)) {
|
|
return false;
|
|
}
|
|
}
|
|
if (plt_rel_ != nullptr) {
|
|
DEBUG("[ relocating %s plt ]", name);
|
|
if (!relocate(plt_rel_, plt_rel_count_, global_group, local_group)) {
|
|
return false;
|
|
}
|
|
}
|
|
#endif
|
|
|
|
#if defined(__mips__)
|
|
if (!mips_relocate_got(global_group, local_group)) {
|
|
return false;
|
|
}
|
|
#endif
|
|
|
|
DEBUG("[ finished linking %s ]", name);
|
|
|
|
#if !defined(__LP64__)
|
|
if (has_text_relocations) {
|
|
// All relocations are done, we can protect our segments back to read-only.
|
|
if (phdr_table_protect_segments(phdr, phnum, load_bias) < 0) {
|
|
DL_ERR("can't protect segments for \"%s\": %s",
|
|
name, strerror(errno));
|
|
return false;
|
|
}
|
|
}
|
|
#endif
|
|
|
|
/* We can also turn on GNU RELRO protection */
|
|
if (phdr_table_protect_gnu_relro(phdr, phnum, load_bias) < 0) {
|
|
DL_ERR("can't enable GNU RELRO protection for \"%s\": %s",
|
|
name, strerror(errno));
|
|
return false;
|
|
}
|
|
|
|
/* Handle serializing/sharing the RELRO segment */
|
|
if (extinfo && (extinfo->flags & ANDROID_DLEXT_WRITE_RELRO)) {
|
|
if (phdr_table_serialize_gnu_relro(phdr, phnum, load_bias,
|
|
extinfo->relro_fd) < 0) {
|
|
DL_ERR("failed serializing GNU RELRO section for \"%s\": %s",
|
|
name, strerror(errno));
|
|
return false;
|
|
}
|
|
} else if (extinfo && (extinfo->flags & ANDROID_DLEXT_USE_RELRO)) {
|
|
if (phdr_table_map_gnu_relro(phdr, phnum, load_bias,
|
|
extinfo->relro_fd) < 0) {
|
|
DL_ERR("failed mapping GNU RELRO section for \"%s\": %s",
|
|
name, strerror(errno));
|
|
return false;
|
|
}
|
|
}
|
|
|
|
notify_gdb_of_load(this);
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* This function add vdso to internal dso list.
|
|
* It helps to stack unwinding through signal handlers.
|
|
* Also, it makes bionic more like glibc.
|
|
*/
|
|
static void add_vdso(KernelArgumentBlock& args __unused) {
|
|
#if defined(AT_SYSINFO_EHDR)
|
|
ElfW(Ehdr)* ehdr_vdso = reinterpret_cast<ElfW(Ehdr)*>(args.getauxval(AT_SYSINFO_EHDR));
|
|
if (ehdr_vdso == nullptr) {
|
|
return;
|
|
}
|
|
|
|
soinfo* si = soinfo_alloc("[vdso]", nullptr, 0, 0);
|
|
|
|
si->phdr = reinterpret_cast<ElfW(Phdr)*>(reinterpret_cast<char*>(ehdr_vdso) + ehdr_vdso->e_phoff);
|
|
si->phnum = ehdr_vdso->e_phnum;
|
|
si->base = reinterpret_cast<ElfW(Addr)>(ehdr_vdso);
|
|
si->size = phdr_table_get_load_size(si->phdr, si->phnum);
|
|
si->load_bias = get_elf_exec_load_bias(ehdr_vdso);
|
|
|
|
si->prelink_image();
|
|
si->link_image(g_empty_list, soinfo::soinfo_list_t::make_list(si), nullptr);
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* This is linker soinfo for GDB. See details below.
|
|
*/
|
|
#if defined(__LP64__)
|
|
#define LINKER_PATH "/system/bin/linker64"
|
|
#else
|
|
#define LINKER_PATH "/system/bin/linker"
|
|
#endif
|
|
static soinfo linker_soinfo_for_gdb(LINKER_PATH, nullptr, 0, 0);
|
|
|
|
/* gdb expects the linker to be in the debug shared object list.
|
|
* Without this, gdb has trouble locating the linker's ".text"
|
|
* and ".plt" sections. Gdb could also potentially use this to
|
|
* relocate the offset of our exported 'rtld_db_dlactivity' symbol.
|
|
* Don't use soinfo_alloc(), because the linker shouldn't
|
|
* be on the soinfo list.
|
|
*/
|
|
static void init_linker_info_for_gdb(ElfW(Addr) linker_base) {
|
|
linker_soinfo_for_gdb.base = linker_base;
|
|
|
|
/*
|
|
* Set the dynamic field in the link map otherwise gdb will complain with
|
|
* the following:
|
|
* warning: .dynamic section for "/system/bin/linker" is not at the
|
|
* expected address (wrong library or version mismatch?)
|
|
*/
|
|
ElfW(Ehdr)* elf_hdr = reinterpret_cast<ElfW(Ehdr)*>(linker_base);
|
|
ElfW(Phdr)* phdr = reinterpret_cast<ElfW(Phdr)*>(linker_base + elf_hdr->e_phoff);
|
|
phdr_table_get_dynamic_section(phdr, elf_hdr->e_phnum, linker_base,
|
|
&linker_soinfo_for_gdb.dynamic, nullptr);
|
|
insert_soinfo_into_debug_map(&linker_soinfo_for_gdb);
|
|
}
|
|
|
|
/*
|
|
* This code is called after the linker has linked itself and
|
|
* fixed it's own GOT. It is safe to make references to externs
|
|
* and other non-local data at this point.
|
|
*/
|
|
static ElfW(Addr) __linker_init_post_relocation(KernelArgumentBlock& args, ElfW(Addr) linker_base) {
|
|
#if TIMING
|
|
struct timeval t0, t1;
|
|
gettimeofday(&t0, 0);
|
|
#endif
|
|
|
|
// Initialize environment functions, and get to the ELF aux vectors table.
|
|
linker_env_init(args);
|
|
|
|
// If this is a setuid/setgid program, close the security hole described in
|
|
// ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-02:23.stdio.asc
|
|
if (get_AT_SECURE()) {
|
|
nullify_closed_stdio();
|
|
}
|
|
|
|
debuggerd_init();
|
|
|
|
// Get a few environment variables.
|
|
const char* LD_DEBUG = linker_env_get("LD_DEBUG");
|
|
if (LD_DEBUG != nullptr) {
|
|
g_ld_debug_verbosity = atoi(LD_DEBUG);
|
|
}
|
|
|
|
// Normally, these are cleaned by linker_env_init, but the test
|
|
// doesn't cost us anything.
|
|
const char* ldpath_env = nullptr;
|
|
const char* ldpreload_env = nullptr;
|
|
if (!get_AT_SECURE()) {
|
|
ldpath_env = linker_env_get("LD_LIBRARY_PATH");
|
|
ldpreload_env = linker_env_get("LD_PRELOAD");
|
|
}
|
|
|
|
#if !defined(__LP64__)
|
|
if (personality(PER_LINUX32) == -1) {
|
|
__libc_fatal("error setting PER_LINUX32 personality: %s", strerror(errno));
|
|
}
|
|
#endif
|
|
|
|
INFO("[ android linker & debugger ]");
|
|
|
|
soinfo* si = soinfo_alloc(args.argv[0], nullptr, 0, RTLD_GLOBAL);
|
|
if (si == nullptr) {
|
|
exit(EXIT_FAILURE);
|
|
}
|
|
|
|
/* bootstrap the link map, the main exe always needs to be first */
|
|
si->set_main_executable();
|
|
link_map* map = &(si->link_map_head);
|
|
|
|
map->l_addr = 0;
|
|
map->l_name = args.argv[0];
|
|
map->l_prev = nullptr;
|
|
map->l_next = nullptr;
|
|
|
|
_r_debug.r_map = map;
|
|
r_debug_tail = map;
|
|
|
|
init_linker_info_for_gdb(linker_base);
|
|
|
|
// Extract information passed from the kernel.
|
|
si->phdr = reinterpret_cast<ElfW(Phdr)*>(args.getauxval(AT_PHDR));
|
|
si->phnum = args.getauxval(AT_PHNUM);
|
|
si->entry = args.getauxval(AT_ENTRY);
|
|
|
|
/* Compute the value of si->base. We can't rely on the fact that
|
|
* the first entry is the PHDR because this will not be true
|
|
* for certain executables (e.g. some in the NDK unit test suite)
|
|
*/
|
|
si->base = 0;
|
|
si->size = phdr_table_get_load_size(si->phdr, si->phnum);
|
|
si->load_bias = 0;
|
|
for (size_t i = 0; i < si->phnum; ++i) {
|
|
if (si->phdr[i].p_type == PT_PHDR) {
|
|
si->load_bias = reinterpret_cast<ElfW(Addr)>(si->phdr) - si->phdr[i].p_vaddr;
|
|
si->base = reinterpret_cast<ElfW(Addr)>(si->phdr) - si->phdr[i].p_offset;
|
|
break;
|
|
}
|
|
}
|
|
si->dynamic = nullptr;
|
|
|
|
ElfW(Ehdr)* elf_hdr = reinterpret_cast<ElfW(Ehdr)*>(si->base);
|
|
if (elf_hdr->e_type != ET_DYN) {
|
|
__libc_format_fd(2, "error: only position independent executables (PIE) are supported.\n");
|
|
exit(EXIT_FAILURE);
|
|
}
|
|
|
|
// Use LD_LIBRARY_PATH and LD_PRELOAD (but only if we aren't setuid/setgid).
|
|
parse_LD_LIBRARY_PATH(ldpath_env);
|
|
parse_LD_PRELOAD(ldpreload_env);
|
|
|
|
somain = si;
|
|
|
|
if (!si->prelink_image()) {
|
|
__libc_format_fd(2, "CANNOT LINK EXECUTABLE: %s\n", linker_get_error_buffer());
|
|
exit(EXIT_FAILURE);
|
|
}
|
|
|
|
// add somain to global group
|
|
si->set_dt_flags_1(si->get_dt_flags_1() | DF_1_GLOBAL);
|
|
|
|
// Load ld_preloads and dependencies.
|
|
StringLinkedList needed_library_name_list;
|
|
size_t needed_libraries_count = 0;
|
|
size_t ld_preloads_count = 0;
|
|
while (g_ld_preload_names[ld_preloads_count] != nullptr) {
|
|
needed_library_name_list.push_back(g_ld_preload_names[ld_preloads_count++]);
|
|
++needed_libraries_count;
|
|
}
|
|
|
|
for_each_dt_needed(si, [&](const char* name) {
|
|
needed_library_name_list.push_back(name);
|
|
++needed_libraries_count;
|
|
});
|
|
|
|
const char* needed_library_names[needed_libraries_count];
|
|
|
|
memset(needed_library_names, 0, sizeof(needed_library_names));
|
|
needed_library_name_list.copy_to_array(needed_library_names, needed_libraries_count);
|
|
|
|
if (needed_libraries_count > 0 && !find_libraries(si, needed_library_names, needed_libraries_count, nullptr, g_ld_preloads, ld_preloads_count, RTLD_GLOBAL, nullptr)) {
|
|
__libc_format_fd(2, "CANNOT LINK EXECUTABLE: %s\n", linker_get_error_buffer());
|
|
exit(EXIT_FAILURE);
|
|
} else if (needed_libraries_count == 0) {
|
|
if (!si->link_image(g_empty_list, soinfo::soinfo_list_t::make_list(si), nullptr)) {
|
|
__libc_format_fd(2, "CANNOT LINK EXECUTABLE: %s\n", linker_get_error_buffer());
|
|
exit(EXIT_FAILURE);
|
|
}
|
|
si->increment_ref_count();
|
|
}
|
|
|
|
add_vdso(args);
|
|
|
|
{
|
|
ProtectedDataGuard guard;
|
|
|
|
si->call_pre_init_constructors();
|
|
|
|
/* After the prelink_image, the si->load_bias is initialized.
|
|
* For so lib, the map->l_addr will be updated in notify_gdb_of_load.
|
|
* We need to update this value for so exe here. So Unwind_Backtrace
|
|
* for some arch like x86 could work correctly within so exe.
|
|
*/
|
|
map->l_addr = si->load_bias;
|
|
si->call_constructors();
|
|
}
|
|
|
|
#if TIMING
|
|
gettimeofday(&t1, nullptr);
|
|
PRINT("LINKER TIME: %s: %d microseconds", args.argv[0], (int) (
|
|
(((long long)t1.tv_sec * 1000000LL) + (long long)t1.tv_usec) -
|
|
(((long long)t0.tv_sec * 1000000LL) + (long long)t0.tv_usec)));
|
|
#endif
|
|
#if STATS
|
|
PRINT("RELO STATS: %s: %d abs, %d rel, %d copy, %d symbol", args.argv[0],
|
|
linker_stats.count[kRelocAbsolute],
|
|
linker_stats.count[kRelocRelative],
|
|
linker_stats.count[kRelocCopy],
|
|
linker_stats.count[kRelocSymbol]);
|
|
#endif
|
|
#if COUNT_PAGES
|
|
{
|
|
unsigned n;
|
|
unsigned i;
|
|
unsigned count = 0;
|
|
for (n = 0; n < 4096; n++) {
|
|
if (bitmask[n]) {
|
|
unsigned x = bitmask[n];
|
|
#if defined(__LP64__)
|
|
for (i = 0; i < 32; i++) {
|
|
#else
|
|
for (i = 0; i < 8; i++) {
|
|
#endif
|
|
if (x & 1) {
|
|
count++;
|
|
}
|
|
x >>= 1;
|
|
}
|
|
}
|
|
}
|
|
PRINT("PAGES MODIFIED: %s: %d (%dKB)", args.argv[0], count, count * 4);
|
|
}
|
|
#endif
|
|
|
|
#if TIMING || STATS || COUNT_PAGES
|
|
fflush(stdout);
|
|
#endif
|
|
|
|
TRACE("[ Ready to execute '%s' @ %p ]", si->name, reinterpret_cast<void*>(si->entry));
|
|
return si->entry;
|
|
}
|
|
|
|
/* Compute the load-bias of an existing executable. This shall only
|
|
* be used to compute the load bias of an executable or shared library
|
|
* that was loaded by the kernel itself.
|
|
*
|
|
* Input:
|
|
* elf -> address of ELF header, assumed to be at the start of the file.
|
|
* Return:
|
|
* load bias, i.e. add the value of any p_vaddr in the file to get
|
|
* the corresponding address in memory.
|
|
*/
|
|
static ElfW(Addr) get_elf_exec_load_bias(const ElfW(Ehdr)* elf) {
|
|
ElfW(Addr) offset = elf->e_phoff;
|
|
const ElfW(Phdr)* phdr_table = reinterpret_cast<const ElfW(Phdr)*>(reinterpret_cast<uintptr_t>(elf) + offset);
|
|
const ElfW(Phdr)* phdr_end = phdr_table + elf->e_phnum;
|
|
|
|
for (const ElfW(Phdr)* phdr = phdr_table; phdr < phdr_end; phdr++) {
|
|
if (phdr->p_type == PT_LOAD) {
|
|
return reinterpret_cast<ElfW(Addr)>(elf) + phdr->p_offset - phdr->p_vaddr;
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
extern "C" void _start();
|
|
|
|
/*
|
|
* This is the entry point for the linker, called from begin.S. This
|
|
* method is responsible for fixing the linker's own relocations, and
|
|
* then calling __linker_init_post_relocation().
|
|
*
|
|
* Because this method is called before the linker has fixed it's own
|
|
* relocations, any attempt to reference an extern variable, extern
|
|
* function, or other GOT reference will generate a segfault.
|
|
*/
|
|
extern "C" ElfW(Addr) __linker_init(void* raw_args) {
|
|
KernelArgumentBlock args(raw_args);
|
|
|
|
ElfW(Addr) linker_addr = args.getauxval(AT_BASE);
|
|
ElfW(Addr) entry_point = args.getauxval(AT_ENTRY);
|
|
ElfW(Ehdr)* elf_hdr = reinterpret_cast<ElfW(Ehdr)*>(linker_addr);
|
|
ElfW(Phdr)* phdr = reinterpret_cast<ElfW(Phdr)*>(linker_addr + elf_hdr->e_phoff);
|
|
|
|
soinfo linker_so("[dynamic linker]", nullptr, 0, 0);
|
|
|
|
// If the linker is not acting as PT_INTERP entry_point is equal to
|
|
// _start. Which means that the linker is running as an executable and
|
|
// already linked by PT_INTERP.
|
|
//
|
|
// This happens when user tries to run 'adb shell /system/bin/linker'
|
|
// see also https://code.google.com/p/android/issues/detail?id=63174
|
|
if (reinterpret_cast<ElfW(Addr)>(&_start) == entry_point) {
|
|
__libc_fatal("This is %s, the helper program for shared library executables.\n", args.argv[0]);
|
|
}
|
|
|
|
linker_so.base = linker_addr;
|
|
linker_so.size = phdr_table_get_load_size(phdr, elf_hdr->e_phnum);
|
|
linker_so.load_bias = get_elf_exec_load_bias(elf_hdr);
|
|
linker_so.dynamic = nullptr;
|
|
linker_so.phdr = phdr;
|
|
linker_so.phnum = elf_hdr->e_phnum;
|
|
linker_so.set_linker_flag();
|
|
|
|
// This might not be obvious... The reasons why we pass g_empty_list
|
|
// in place of local_group here are (1) we do not really need it, because
|
|
// linker is built with DT_SYMBOLIC and therefore relocates its symbols against
|
|
// itself without having to look into local_group and (2) allocators
|
|
// are not yet initialized, and therefore we cannot use linked_list.push_*
|
|
// functions at this point.
|
|
if (!(linker_so.prelink_image() && linker_so.link_image(g_empty_list, g_empty_list, nullptr))) {
|
|
// It would be nice to print an error message, but if the linker
|
|
// can't link itself, there's no guarantee that we'll be able to
|
|
// call write() (because it involves a GOT reference). We may as
|
|
// well try though...
|
|
const char* msg = "CANNOT LINK EXECUTABLE: ";
|
|
write(2, msg, strlen(msg));
|
|
write(2, __linker_dl_err_buf, strlen(__linker_dl_err_buf));
|
|
write(2, "\n", 1);
|
|
_exit(EXIT_FAILURE);
|
|
}
|
|
|
|
__libc_init_tls(args);
|
|
|
|
// Initialize the linker's own global variables
|
|
linker_so.call_constructors();
|
|
|
|
// Initialize static variables. Note that in order to
|
|
// get correct libdl_info we need to call constructors
|
|
// before get_libdl_info().
|
|
solist = get_libdl_info();
|
|
sonext = get_libdl_info();
|
|
|
|
// We have successfully fixed our own relocations. It's safe to run
|
|
// the main part of the linker now.
|
|
args.abort_message_ptr = &g_abort_message;
|
|
ElfW(Addr) start_address = __linker_init_post_relocation(args, linker_addr);
|
|
|
|
INFO("[ jumping to _start ]");
|
|
|
|
// Return the address that the calling assembly stub should jump to.
|
|
return start_address;
|
|
}
|