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FORTIFY_SOURCE: add umask check

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Verify that the call to umask makes sense. While this wouldn't
have detected bug 7094213 (because the low order bits were all zero),
it might detect other similar bugs.

References: https://code.google.com/p/android-source-browsing/source/detail?r=acba45cc4b1f98f67fcdeda2f7c13ed57659b92a&repo=platform--libcore

Change-Id: I966a531d6b3cf8e1c5eacd69bd3cbec475b5fa58
This commit is contained in:
Nick Kralevich 2012-09-26 10:02:30 -07:00
parent 6e0e03c38b
commit cd587701c8
3 changed files with 75 additions and 0 deletions
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1
libc/Android.mk
View file

@ -257,6 +257,7 @@ libc_common_src_files := \
tzcode/strftime.c \
tzcode/strptime.c \
bionic/__set_errno.c \
bionic/__umask_chk.c \
bionic/bionic_clone.c \
bionic/cpuacct.c \
bionic/arc4random.c \

53
libc/bionic/__umask_chk.c Normal file
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@ -0,0 +1,53 @@
/*
* Copyright (C) 2012 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 <sys/types.h>
#include <sys/stat.h>
#include <private/logd.h>
#include <stdlib.h>
/*
* Runtime implementation of __umask_chk.
*
* Validate that umask is called with sane mode.
*
* This umask check is called if _FORTIFY_SOURCE is defined and
* greater than 0.
*/
mode_t __umask_chk(mode_t mode)
{
if ((mode & 0777) != mode) {
__libc_android_log_print(ANDROID_LOG_FATAL, "libc",
"*** FORTIFY_SOURCE: umask called with invalid mask ***\n");
abort();
}
return umask(mode);
}

21
libc/include/sys/stat.h
View file

@ -122,6 +122,27 @@ extern int lstat(const char *, struct stat *);
extern int mknod(const char *, mode_t, dev_t);
extern mode_t umask(mode_t);
#if defined(__BIONIC_FORTIFY_INLINE)
extern mode_t __umask_chk(mode_t);
extern mode_t __umask_real(mode_t)
__asm__(__USER_LABEL_PREFIX__ "umask");
extern void __umask_error()
__attribute__((__error__("umask called with invalid mode")));
__BIONIC_FORTIFY_INLINE
mode_t umask(mode_t mode) {
if (__builtin_constant_p(mode)) {
if ((mode & 0777) != mode) {
__umask_error();
}
return __umask_real(mode);
}
return __umask_chk(mode);
}
#endif /* defined(__BIONIC_FORTIFY_INLINE) */
#define stat64 stat
#define fstat64 fstat
#define lstat64 lstat