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FORTIFY_SOURCE: add open() checks

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Add a FORTIFY_SOURCE check which requires that you pass a
"mode" argument when calling open(..., O_CREAT). If a mode isn't
passed, then the file is created with "undefined" permissions.

Change-Id: I4427be4f9ce170c69da01af5b00fb05b03613a28
This commit is contained in:
Nick Kralevich 2012-06-26 15:08:06 -07:00
parent b52e4385c4
commit 8118f62a7d
2 changed files with 54 additions and 0 deletions
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40
libc/include/fcntl.h
View File

@ -49,6 +49,46 @@ extern int unlinkat(int dirfd, const char *pathname, int flags);
extern int fcntl(int fd, int command, ...);
extern int creat(const char* path, mode_t mode);
#if defined(__BIONIC_FORTIFY_INLINE)
# if !defined(__clang__)
/*
* Clang doesn't have support for __builtin_va_arg_pack()
* and __builtin_va_arg_pack_len()
*
* http://clang.llvm.org/docs/UsersManual.html#c_unimpl_gcc
*/
extern void __open_creat_error()
__attribute__((__error__ ("open called with O_CREAT, but missing mode")));
extern void __open_toomanyargs_error()
__attribute__((__error__ ("open called with too many arguments")));
extern int __open_real(const char *pathname, int flags, ...)
__asm__(__USER_LABEL_PREFIX__ "open");
extern int __open_2(const char *, int);
__BIONIC_FORTIFY_INLINE
int open(const char *pathname, int flags, ...) {
if (__builtin_constant_p(flags)) {
if ((flags & O_CREAT) && __builtin_va_arg_pack_len() == 0) {
__open_creat_error(); // compile time error
}
}
if (__builtin_va_arg_pack_len() > 1) {
__open_toomanyargs_error(); // compile time error
}
if (__builtin_va_arg_pack_len() == 0) {
return __open_2(pathname, flags);
}
return __open_real(pathname, flags, __builtin_va_arg_pack());
}
#endif /* !defined(__clang__) */
#endif /* defined(__BIONIC_FORTIFY_INLINE) */
__END_DECLS
#endif /* _FCNTL_H */

14
libc/unistd/open.c
View File

@ -28,6 +28,8 @@
#include <unistd.h>
#include <fcntl.h>
#include <stdarg.h>
#include <stdlib.h>
#include <private/logd.h>
extern int __open(const char*, int, int);
@ -49,3 +51,15 @@ int open(const char *pathname, int flags, ...)
return __open(pathname, flags, mode);
}
int __open_2(const char *pathname, int flags) {
if (flags & O_CREAT) {
__libc_android_log_print(ANDROID_LOG_FATAL, "libc",
"*** open(O_CREAT) called without specifying a mode ***\n");
abort();
}
flags |= O_LARGEFILE;
return __open(pathname, flags, 0);
}