REORG: pool: move all the OS specific code to pool-os.h
Till now pool-os used to contain a mapping from pool_{alloc,free}_area()
to pool_{alloc,free}_area_uaf() in case of DEBUG_UAF, or the regular
malloc-based function. And the *_uaf() functions were in pool.c. But
since 2.4 with the first cleanup of the pools, there has been no more
calls to pool_{alloc,free}_area() from anywhere but pool.c, from exactly
one place each. As such, there's no more need to keep *_uaf() apart in
pool.c, we can inline it into pool-os.h and leave all the OS stuff there,
with pool.c calling either based on DEBUG_UAF. This is cleaner with less
round trips between both files and easier to find.
diff --git a/include/haproxy/pool-os.h b/include/haproxy/pool-os.h
index d6612e8..cf29c58 100644
--- a/include/haproxy/pool-os.h
+++ b/include/haproxy/pool-os.h
@@ -22,12 +22,11 @@
#ifndef _HAPROXY_POOL_OS_H
#define _HAPROXY_POOL_OS_H
+#include <sys/mman.h>
#include <stdlib.h>
#include <haproxy/api.h>
-#ifndef DEBUG_UAF
-
/************* normal allocator *************/
/* allocates an area of size <size> and returns it. The semantics are similar
@@ -48,32 +47,57 @@
free(area);
}
-#else
-
/************* use-after-free allocator *************/
-void *pool_alloc_area_uaf(size_t size);
-void pool_free_area_uaf(void *area, size_t size);
-
-
/* allocates an area of size <size> and returns it. The semantics are similar
- * to those of malloc().
+ * to those of malloc(). However the allocation is rounded up to 4kB so that a
+ * full page is allocated. This ensures the object can be freed alone so that
+ * future dereferences are easily detected. The returned object is always
+ * 16-bytes aligned to avoid issues with unaligned structure objects. In case
+ * some padding is added, the area's start address is copied at the end of the
+ * padding to help detect underflows.
*/
-static forceinline void *pool_alloc_area(size_t size)
+static inline void *pool_alloc_area_uaf(size_t size)
{
- return pool_alloc_area_uaf(size);
+ size_t pad = (4096 - size) & 0xFF0;
+ void *ret;
+
+ ret = mmap(NULL, (size + 4095) & -4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
+ if (ret != MAP_FAILED) {
+ /* let's dereference the page before returning so that the real
+ * allocation in the system is performed without holding the lock.
+ */
+ *(int *)ret = 0;
+ if (pad >= sizeof(void *))
+ *(void **)(ret + pad - sizeof(void *)) = ret + pad;
+ ret += pad;
+ } else {
+ ret = NULL;
+ }
+ return ret;
}
-/* frees an area <area> of size <size> allocated by pool_alloc_area(). The
- * semantics are identical to free() except that the size is specified and
- * may be ignored.
+/* frees an area <area> of size <size> allocated by pool_alloc_area_uaf(). The
+ * semantics are identical to free() except that the size must absolutely match
+ * the one passed to pool_alloc_area_uaf(). In case some padding is added, the
+ * area's start address is compared to the one at the end of the padding, and
+ * a segfault is triggered if they don't match, indicating an underflow.
*/
-static forceinline void pool_free_area(void *area, size_t size)
+static inline void pool_free_area_uaf(void *area, size_t size)
{
- pool_free_area_uaf(area, size);
-}
+ size_t pad = (4096 - size) & 0xFF0;
-#endif /* DEBUG_UAF */
+ /* This object will be released for real in order to detect a use after
+ * free. We also force a write to the area to ensure we crash on double
+ * free or free of a const area.
+ */
+ *(uint32_t *)area = 0xDEADADD4;
+
+ if (pad >= sizeof(void *) && *(void **)(area - sizeof(void *)) != area)
+ ABORT_NOW();
+
+ munmap(area - pad, (size + 4095) & -4096);
+}
#endif /* _HAPROXY_POOL_OS_H */
diff --git a/src/pool.c b/src/pool.c
index ddea4c0..8b33247 100644
--- a/src/pool.c
+++ b/src/pool.c
@@ -10,7 +10,6 @@
*
*/
-#include <sys/mman.h>
#include <errno.h>
#include <haproxy/activity.h>
@@ -336,7 +335,12 @@
void *pool_get_from_os(struct pool_head *pool)
{
if (!pool->limit || pool->allocated < pool->limit) {
- void *ptr = pool_alloc_area(pool->alloc_sz);
+ void *ptr;
+#ifdef DEBUG_UAF
+ ptr = pool_alloc_area_uaf(pool->alloc_sz);
+#else
+ ptr = pool_alloc_area(pool->alloc_sz);
+#endif
if (ptr) {
_HA_ATOMIC_INC(&pool->allocated);
return ptr;
@@ -353,7 +357,11 @@
*/
void pool_put_to_os(struct pool_head *pool, void *ptr)
{
+#ifdef DEBUG_UAF
+ pool_free_area_uaf(ptr, pool->alloc_sz);
+#else
pool_free_area(ptr, pool->alloc_sz);
+#endif
_HA_ATOMIC_DEC(&pool->allocated);
}
@@ -787,63 +795,6 @@
pool_put_to_cache(pool, ptr, caller);
}
-
-#ifdef DEBUG_UAF
-
-/************* use-after-free allocator *************/
-
-/* allocates an area of size <size> and returns it. The semantics are similar
- * to those of malloc(). However the allocation is rounded up to 4kB so that a
- * full page is allocated. This ensures the object can be freed alone so that
- * future dereferences are easily detected. The returned object is always
- * 16-bytes aligned to avoid issues with unaligned structure objects. In case
- * some padding is added, the area's start address is copied at the end of the
- * padding to help detect underflows.
- */
-void *pool_alloc_area_uaf(size_t size)
-{
- size_t pad = (4096 - size) & 0xFF0;
- void *ret;
-
- ret = mmap(NULL, (size + 4095) & -4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
- if (ret != MAP_FAILED) {
- /* let's dereference the page before returning so that the real
- * allocation in the system is performed without holding the lock.
- */
- *(int *)ret = 0;
- if (pad >= sizeof(void *))
- *(void **)(ret + pad - sizeof(void *)) = ret + pad;
- ret += pad;
- } else {
- ret = NULL;
- }
- return ret;
-}
-
-/* frees an area <area> of size <size> allocated by pool_alloc_area(). The
- * semantics are identical to free() except that the size must absolutely match
- * the one passed to pool_alloc_area(). In case some padding is added, the
- * area's start address is compared to the one at the end of the padding, and
- * a segfault is triggered if they don't match, indicating an underflow.
- */
-void pool_free_area_uaf(void *area, size_t size)
-{
- size_t pad = (4096 - size) & 0xFF0;
-
- /* This object will be released for real in order to detect a use after
- * free. We also force a write to the area to ensure we crash on double
- * free or free of a const area.
- */
- *(uint32_t *)area = 0xDEADADD4;
-
- if (pad >= sizeof(void *) && *(void **)(area - sizeof(void *)) != area)
- ABORT_NOW();
-
- munmap(area - pad, (size + 4095) & -4096);
-}
-
-#endif /* DEBUG_UAF */
-
/*
* This function destroys a pool by freeing it completely, unless it's still
* in use. This should be called only under extreme circumstances. It always