standlone fortify heaaders
9e65ae387c
First, we should never check the size of __s if __l == 0 since the array is not going to be modified in that case. Second, negative __l is a well-defined error case (EINVAL) and we should never trap on a conforming code like this: r = getgroups(-1, NULL); if (r == -1) ... An example of non-desired behaviour for negative __l is the gnulib configure script which checks for getgroups(-1, ...) to catch some ancient FreeBSD kernel bug. The conftest binary traps even on good system (e.g. linux/musl) and the unnecessary getgroups wrapper is enforced for any project that uses gnulib. This patch also changes the size_t cast to avoid the explicit zero extension on systems where size_t differs from unsigned int. |
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| include | ||
| LICENSE | ||
| Makefile | ||
| README | ||
What is it?
===========
This is a standalone implementation of fortify source[0]. It provides
compile time buffer checks. It is libc-agnostic and simply overlays the
system headers by using the #include_next extension found in GCC. It was
initially intended to be used on musl[1] based Linux distributions[2].
Features
========
- It is portable, works on *BSD, Linux, Solaris and possibly others.
- It will only trap non-conformant programs. This means that fortify
level 2 is treated in the same way as level 1.
- Avoids making function calls when undefined behaviour has already been
invoked. This is handled by using __builtin_trap().
- Support for out-of-bounds read interfaces, such as send(), write(),
fwrite() etc.
- No ABI is enforced. All of the fortify check functions are inlined
into the resulting binary.
Sample usage
============
If you want to quickly test it, you can try something like the following:
cat > fgets.c <<EOF
#include <stdio.h>
int
main(void)
{
char buf[BUFSIZ];
fgets(buf, sizeof(buf) + 1, stdin);
return 0;
}
EOF
cc -I<path-to-fortify-include-dir> -D_FORTIFY_SOURCE=1 -O1 fgets.c
./a.out
At this point, the program will safely crash.
Supported interfaces
====================
FD_CLR
FD_SET
bcopy
bzero
confstr
fgets
fgetws
fread
fwrite
getcwd
getdomainname
getgroups
gethostname
getlogin_r
mbsnrtowcs
mbsrtowcs
mbstowcs
memcpy
memmove
mempcpy
memset
poll
ppoll
pread
read
readlink
readlinkat
realpath
recv
recvfrom
send
sendto
snprintf
sprintf
stpcpy
stpncpy
strcat
strcpy
strlcat
strlcpy
strncat
strncpy
ttyname_r
vsnprintf
vsprintf
wcrtomb
wcscat
wcscpy
wcsncat
wcsncpy
wcsnrtombs
wcsrtombs
wcstombs
wctomb
wmemcpy
wmemmove
wmemset
write
[0] http://gcc.gnu.org/ml/gcc-patches/2004-09/msg02055.html
[1] http://www.musl-libc.org/
[2] http://git.alpinelinux.org/cgit/aports/commit/?id=067a4f28825478911bb62be3b8da758d9722753e