cube0x8 c79cdc89ac
add mmap hooks to libqasan (#2122)
* add mmap hooks to libqasan

---------

Co-authored-by: Romain Malmain <romain.malmain@pm.me>
2024-05-02 10:39:33 +02:00

119 lines
3.3 KiB
C

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/*
Mmap hooks for libqasan by Alessandro "cube" De Vito
<alessandro.devito@stackbits.eu>
*/
#include "libqasan.h"
#include <features.h>
#include <errno.h>
#include <stddef.h>
#include <assert.h>
#include <pthread.h>
#include <sys/mman.h>
#ifdef __GLIBC__
#define USE_LIBC_ALLOC
#endif
#if __STDC_VERSION__ < 201112L || \
(defined(__FreeBSD__) && __FreeBSD_version < 1200000)
// use this hack if not C11
typedef struct {
long long __ll;
long double __ld;
} max_align_t;
#endif
#ifdef USE_LIBC_ALLOC
void *(*__lq_libc_mmap)(void *, size_t, int, int, int, off_t);
int (*__lq_libc_munmap)(void *, size_t);
#else
// TODO: include from mmap.c
#endif
int __libqasan_mmap_initialized;
void __libqasan_init_mmap(void) {
if (__libqasan_mmap_initialized) return;
#ifdef USE_LIBC_ALLOC
__lq_libc_mmap = dlsym(RTLD_NEXT, "mmap");
__lq_libc_munmap = dlsym(RTLD_NEXT, "munmap");
#endif
__libqasan_mmap_initialized = 1;
QASAN_LOG("\n");
QASAN_LOG("mmap initialization done.\n");
QASAN_LOG("\n");
}
void *__libqasan_mmap(void *addr, size_t length, int prot, int flags, int fd,
off_t offset) {
__libqasan_init_mmap();
int state = QASAN_SWAP(QASAN_DISABLED); // disable qasan for this thread
void *p = __lq_libc_mmap(addr, length, prot, flags, fd, offset);
QASAN_SWAP(state);
if (!p) return NULL;
QASAN_UNPOISON(p, length);
QASAN_ALLOC(p, (uintptr_t)p + length);
// We don't memset the memory, as it's not guaranteed to be writable.
return p;
}
int __libqasan_munmap(void *addr, size_t length) {
__libqasan_init_mmap();
int state = QASAN_SWAP(QASAN_DISABLED); // disable qasan for this thread
int ret = __lq_libc_munmap(addr, length);
QASAN_SWAP(state);
if (ret == -1) return -1;
// Omitting memory poisoning for unmapped regions as accessing them would
// result in an error anyway.
// TODO: add a syscall to deallocate addr->addr + length
QASAN_DEALLOC(addr);
return ret;
}