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add fortified readlink/readlinkat implementations

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Change-Id: Ia4b1824d20cad3a072b9162047492dade8576779
This commit is contained in:
Daniel Micay 2015-04-17 11:26:36 -04:00
parent 3875744f89
commit 42281880a8
6 changed files with 162 additions and 0 deletions
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2
libc/Android.mk
View File

@ -74,6 +74,8 @@ libc_common_src_files += \
bionic/__pread64_chk.cpp \
bionic/__pread_chk.cpp \
bionic/__read_chk.cpp \
bionic/__readlink_chk.cpp \
bionic/__readlinkat_chk.cpp \
bionic/__recvfrom_chk.cpp \
bionic/__stpcpy_chk.cpp \
bionic/__stpncpy_chk.cpp \

43
libc/bionic/__readlink_chk.cpp Normal file
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@ -0,0 +1,43 @@
/*
* Copyright (C) 2015 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.
*/
#undef _FORTIFY_SOURCE
#include <unistd.h>
#include "private/libc_logging.h"
extern "C" ssize_t __readlink_chk(const char* path, char* buf, size_t size, size_t buf_size) {
if (__predict_false(size > buf_size)) {
__fortify_chk_fail("readlink: prevented write past end of buffer", 0);
}
if (__predict_false(size > SSIZE_MAX)) {
__fortify_chk_fail("readlink: size > SSIZE_MAX", 0);
}
return readlink(path, buf, size);
}

43
libc/bionic/__readlinkat_chk.cpp Normal file
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@ -0,0 +1,43 @@
/*
* Copyright (C) 2015 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.
*/
#undef _FORTIFY_SOURCE
#include <unistd.h>
#include "private/libc_logging.h"
extern "C" ssize_t __readlinkat_chk(int dirfd, const char* path, char* buf, size_t size, size_t buf_size) {
if (__predict_false(size > buf_size)) {
__fortify_chk_fail("readlinkat: prevented write past end of buffer", 0);
}
if (__predict_false(size > SSIZE_MAX)) {
__fortify_chk_fail("readlinkat: size > SSIZE_MAX", 0);
}
return readlinkat(dirfd, path, buf, size);
}

2
libc/bionic/readlink.cpp
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@ -26,6 +26,8 @@
* SUCH DAMAGE.
*/
#undef _FORTIFY_SOURCE
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>

60
libc/include/unistd.h
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@ -239,6 +239,16 @@ __errordecl(__read_dest_size_error, "read called with size bigger than destinati
__errordecl(__read_count_toobig_error, "read called with count > SSIZE_MAX");
extern ssize_t __read_real(int, void*, size_t) __RENAME(read);
extern ssize_t __readlink_chk(const char*, char*, size_t, size_t);
__errordecl(__readlink_dest_size_error, "readlink called with size bigger than destination");
__errordecl(__readlink_size_toobig_error, "readlink called with size > SSIZE_MAX");
extern ssize_t __readlink_real(const char*, char*, size_t) __RENAME(readlink);
extern ssize_t __readlinkat_chk(int dirfd, const char*, char*, size_t, size_t);
__errordecl(__readlinkat_dest_size_error, "readlinkat called with size bigger than destination");
__errordecl(__readlinkat_size_toobig_error, "readlinkat called with size > SSIZE_MAX");
extern ssize_t __readlinkat_real(int dirfd, const char*, char*, size_t) __RENAME(readlinkat);
#if defined(__BIONIC_FORTIFY)
#if defined(__USE_FILE_OFFSET64)
@ -322,6 +332,56 @@ ssize_t read(int fd, void* buf, size_t count) {
return __read_chk(fd, buf, count, bos);
}
__BIONIC_FORTIFY_INLINE
ssize_t readlink(const char* path, char* buf, size_t size) {
size_t bos = __bos(buf);
#if !defined(__clang__)
if (__builtin_constant_p(size) && (size > SSIZE_MAX)) {
__readlink_size_toobig_error();
}
if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
return __readlink_real(path, buf, size);
}
if (__builtin_constant_p(size) && (size > bos)) {
__readlink_dest_size_error();
}
if (__builtin_constant_p(size) && (size <= bos)) {
return __readlink_real(path, buf, size);
}
#endif
return __readlink_chk(path, buf, size, bos);
}
__BIONIC_FORTIFY_INLINE
ssize_t readlinkat(int dirfd, const char* path, char* buf, size_t size) {
size_t bos = __bos(buf);
#if !defined(__clang__)
if (__builtin_constant_p(size) && (size > SSIZE_MAX)) {
__readlinkat_size_toobig_error();
}
if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
return __readlinkat_real(dirfd, path, buf, size);
}
if (__builtin_constant_p(size) && (size > bos)) {
__readlinkat_dest_size_error();
}
if (__builtin_constant_p(size) && (size <= bos)) {
return __readlinkat_real(dirfd, path, buf, size);
}
#endif
return __readlinkat_chk(dirfd, path, buf, size, bos);
}
#endif /* defined(__BIONIC_FORTIFY) */
__END_DECLS

12
tests/fortify_test.cpp
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@ -647,6 +647,18 @@ TEST_F(DEATHTEST, read_fortified) {
close(fd);
}
TEST_F(DEATHTEST, readlink_fortified) {
char buf[1];
size_t ct = atoi("2"); // prevent optimizations
ASSERT_FORTIFY(readlink("/dev/null", buf, ct));
}
TEST_F(DEATHTEST, readlinkat_fortified) {
char buf[1];
size_t ct = atoi("2"); // prevent optimizations
ASSERT_FORTIFY(readlinkat(AT_FDCWD, "/dev/null", buf, ct));
}
extern "C" char* __strncat_chk(char*, const char*, size_t, size_t);
extern "C" char* __strcat_chk(char*, const char*, size_t);