diff --git a/libc/Android.mk b/libc/Android.mk index 360bdc1cf..c98d2ff59 100644 --- a/libc/Android.mk +++ b/libc/Android.mk @@ -275,6 +275,7 @@ libc_bionic_src_files := \ bionic/dirent.cpp \ bionic/eventfd.cpp \ bionic/__fgets_chk.cpp \ + bionic/getauxval.cpp \ bionic/getcwd.cpp \ bionic/libgen.cpp \ bionic/__memcpy_chk.cpp \ diff --git a/libc/bionic/getauxval.cpp b/libc/bionic/getauxval.cpp new file mode 100644 index 000000000..38a05fc21 --- /dev/null +++ b/libc/bionic/getauxval.cpp @@ -0,0 +1,48 @@ +/* + * Copyright (C) 2013 The Android Open Source Project + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * * Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE + * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, + * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS + * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED + * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, + * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT + * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#include +#include +#include +#include +#include + +__LIBC_HIDDEN__ +Elf32_auxv_t* __libc_auxv = NULL; + +extern "C" unsigned long int getauxval(unsigned long int type) { + Elf32_auxv_t* v; + + for (v = __libc_auxv; v->a_type != AT_NULL; v++) { + if (v->a_type == type) { + return v->a_un.a_val; + } + } + + return 0; +} diff --git a/libc/bionic/libc_init_common.c b/libc/bionic/libc_init_common.c index fb164f447..86e1eb574 100644 --- a/libc/bionic/libc_init_common.c +++ b/libc/bionic/libc_init_common.c @@ -38,6 +38,7 @@ #include #include +#include extern unsigned __get_sp(void); extern pid_t gettid(void); @@ -95,6 +96,15 @@ void __libc_init_common(uintptr_t* elf_data) { __progname = argv[0] ? argv[0] : ""; environ = envp; + // The auxiliary vector is at the end of the environment block + while(*envp != NULL) { + envp++; + } + /* The end of the environment block is marked by two NULL pointers */ + envp++; + + __libc_auxv = (Elf32_auxv_t*) envp; + __system_properties_init(); // Requires 'environ'. } diff --git a/libc/bionic/libc_init_static.c b/libc/bionic/libc_init_static.c index ba7f008e9..bb3a41021 100644 --- a/libc/bionic/libc_init_static.c +++ b/libc/bionic/libc_init_static.c @@ -49,6 +49,7 @@ #include #include #include +#include // Returns the address of the page containing address 'x'. #define PAGE_START(x) ((x) & PAGE_MASK) @@ -65,27 +66,13 @@ static void call_array(void(**list)()) } } -/* - * Find the value of the AT_* variable passed to us by the kernel. - */ -static unsigned find_aux(unsigned *vecs, unsigned type) { - while (vecs[0]) { - if (vecs[0] == type) { - return vecs[1]; - } - vecs += 2; - } - - return 0; // should never happen -} - -static void apply_gnu_relro(unsigned *vecs) { +static void apply_gnu_relro() { Elf32_Phdr *phdr_start; - unsigned phdr_ct; + unsigned long int phdr_ct; Elf32_Phdr *phdr; - phdr_start = (Elf32_Phdr *) find_aux(vecs, AT_PHDR); - phdr_ct = find_aux(vecs, AT_PHNUM); + phdr_start = (Elf32_Phdr *) getauxval(AT_PHDR); + phdr_ct = getauxval(AT_PHNUM); for (phdr = phdr_start; phdr < (phdr_start + phdr_ct); phdr++) { if (phdr->p_type != PT_GNU_RELRO) @@ -108,7 +95,6 @@ __noreturn void __libc_init(uintptr_t *elfdata, { int argc; char **argv, **envp; - unsigned *vecs; __libc_init_tls(NULL); @@ -129,14 +115,6 @@ __noreturn void __libc_init(uintptr_t *elfdata, argv = (char**)(elfdata + 1); envp = argv + argc + 1; - // The auxiliary vector is at the end of the environment block - vecs = (unsigned *) envp; - while (vecs[0] != 0) { - vecs++; - } - /* The end of the environment block is marked by two NULL pointers */ - vecs++; - /* The executable may have its own destructors listed in its .fini_array * so we need to ensure that these are called when the program exits * normally. @@ -144,6 +122,6 @@ __noreturn void __libc_init(uintptr_t *elfdata, if (structors->fini_array) __cxa_atexit(__libc_fini,structors->fini_array,NULL); - apply_gnu_relro(vecs); + apply_gnu_relro(); exit(slingshot(argc, argv, envp)); } diff --git a/libc/include/elf.h b/libc/include/elf.h index c3e32264c..ac0f1d2c3 100644 --- a/libc/include/elf.h +++ b/libc/include/elf.h @@ -28,8 +28,23 @@ #ifndef _ELF_H #define _ELF_H +#include #include #include +typedef struct { + uint32_t a_type; + union { + uint32_t a_val; + } a_un; +} Elf32_auxv_t; + +typedef struct { + uint64_t a_type; + union { + uint64_t a_val; + } a_un; +} Elf64_auxv_t; + #endif /* _ELF_H */ diff --git a/libc/include/sys/auxv.h b/libc/include/sys/auxv.h new file mode 100644 index 000000000..918442f54 --- /dev/null +++ b/libc/include/sys/auxv.h @@ -0,0 +1,39 @@ +/* + * Copyright (C) 2013 The Android Open Source Project + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * * Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE + * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, + * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS + * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED + * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, + * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT + * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ +#ifndef _SYS_AUXV_H_ +#define _SYS_AUXV_H_ + +#include + +__BEGIN_DECLS + +unsigned long int getauxval(unsigned long int type); + +__END_DECLS + +#endif /* _SYS_AUXV_H_ */ diff --git a/libc/private/bionic_auxv.h b/libc/private/bionic_auxv.h new file mode 100644 index 000000000..d3b0038d8 --- /dev/null +++ b/libc/private/bionic_auxv.h @@ -0,0 +1,39 @@ +/* + * Copyright (C) 2013 The Android Open Source Project + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * * Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE + * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, + * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS + * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED + * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, + * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT + * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ +#ifndef _SYS_AUXV_H_ +#define _SYS_AUXV_H_ + +#include + +__BEGIN_DECLS + +extern Elf32_auxv_t* __libc_auxv; + +__END_DECLS + +#endif /* _SYS_AUXV_H_ */ diff --git a/tests/Android.mk b/tests/Android.mk index 635c0214c..25da12084 100644 --- a/tests/Android.mk +++ b/tests/Android.mk @@ -55,6 +55,7 @@ test_c_flags = \ test_src_files = \ dirent_test.cpp \ fenv_test.cpp \ + getauxval_test.cpp \ getcwd_test.cpp \ libgen_test.cpp \ pthread_test.cpp \ diff --git a/tests/getauxval_test.cpp b/tests/getauxval_test.cpp new file mode 100644 index 000000000..01c11c3c2 --- /dev/null +++ b/tests/getauxval_test.cpp @@ -0,0 +1,55 @@ +/* + * Copyright (C) 2013 The Android Open Source Project + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +#include +#include +#include + +// getauxval() was only added as of glibc version 2.16. +// See: http://lwn.net/Articles/519085/ +// Don't try to compile this code on older glibc versions. + +#if defined(__BIONIC__) + #define GETAUXVAL_CAN_COMPILE 1 +#elif defined(__GLIBC_PREREQ) + #if __GLIBC_PREREQ(2, 16) + #define GETAUXVAL_CAN_COMPILE 1 + #endif +#endif + +#if defined(GETAUXVAL_CAN_COMPILE) + +#include + +TEST(getauxval, expected_values) { + ASSERT_EQ((unsigned long int) 0, getauxval(AT_SECURE)); + ASSERT_EQ(getuid(), getauxval(AT_UID)); + ASSERT_EQ(geteuid(), getauxval(AT_EUID)); + ASSERT_EQ(getgid(), getauxval(AT_GID)); + ASSERT_EQ(getegid(), getauxval(AT_EGID)); + ASSERT_EQ((unsigned long int) getpagesize(), getauxval(AT_PAGESZ)); + + ASSERT_NE((unsigned long int) 0, getauxval(AT_PHDR)); + ASSERT_NE((unsigned long int) 0, getauxval(AT_PHNUM)); + ASSERT_NE((unsigned long int) 0, getauxval(AT_ENTRY)); + ASSERT_NE((unsigned long int) 0, getauxval(AT_PAGESZ)); +} + +TEST(getauxval, unexpected_values) { + ASSERT_EQ((unsigned long int) 0, getauxval(0xdeadbeef)); +} + +#endif /* GETAUXVAL_CAN_COMPILE */