diff options
| author | Stefan Fritsch <sf@apache.org> | 2014-05-09 20:29:25 +0000 |
|---|---|---|
| committer | Stefan Fritsch <sf@apache.org> | 2014-05-09 20:29:25 +0000 |
| commit | ef852b52037ce2b5b5262ca3414783753be9cc7f (patch) | |
| tree | 1a4536e923b882983b727fb6bd3079f613118263 /memory | |
| parent | 9aaf97b879e299996f5f5c234ca4ce763c35f715 (diff) | |
| download | apr-ef852b52037ce2b5b5262ca3414783753be9cc7f.tar.gz | |
Add option to use guard pages
Add new --enable-allocator-guard-pages configure option which works like
--enable-allocator-uses-mmap, but will also add inaccessible guard pages before
and after each memnode. This will result in higher ressource usage but allow
to find/protect against certain buffer overflow/overread bugs.
git-svn-id: https://svn.apache.org/repos/asf/apr/apr/trunk@1593615 13f79535-47bb-0310-9956-ffa450edef68
Diffstat (limited to 'memory')
| -rw-r--r-- | memory/unix/apr_pools.c | 32 |
1 files changed, 29 insertions, 3 deletions
diff --git a/memory/unix/apr_pools.c b/memory/unix/apr_pools.c index f12f27e9e..fdfe4af6f 100644 --- a/memory/unix/apr_pools.c +++ b/memory/unix/apr_pools.c @@ -40,6 +40,10 @@ #include <unistd.h> /* for getpid and sysconf */ #endif +#if APR_ALLOCATOR_GUARD_PAGES && !APR_ALLOCATOR_USES_MMAP +#define APR_ALLOCATOR_USES_MMAP 1 +#endif + #if APR_ALLOCATOR_USES_MMAP #include <sys/mman.h> #endif @@ -76,6 +80,16 @@ static unsigned int boundary_size; #define BOUNDARY_SIZE (1 << BOUNDARY_INDEX) #endif +#if APR_ALLOCATOR_GUARD_PAGES +#if defined(_SC_PAGESIZE) +#define GUARDPAGE_SIZE boundary_size +#else +#error Cannot determine page size +#endif /* _SC_PAGESIZE */ +#else +#define GUARDPAGE_SIZE 0 +#endif /* APR_ALLOCATOR_GUARD_PAGES */ + /* * Timing constants for killing subprocesses * There is a total 3-second delay between sending a SIGINT @@ -158,7 +172,8 @@ APR_DECLARE(void) apr_allocator_destroy(apr_allocator_t *allocator) while ((node = *ref) != NULL) { *ref = node->next; #if APR_ALLOCATOR_USES_MMAP - munmap(node, (node->index+1) << BOUNDARY_INDEX); + munmap((char *)node - GUARDPAGE_SIZE, + 2 * GUARDPAGE_SIZE + ((node->index+1) << BOUNDARY_INDEX)); #else free(node); #endif @@ -347,7 +362,10 @@ apr_memnode_t *allocator_alloc(apr_allocator_t *allocator, apr_size_t in_size) /* If we haven't got a suitable node, malloc a new one * and initialize it. */ -#if APR_ALLOCATOR_USES_MMAP +#if APR_ALLOCATOR_GUARD_PAGES + if ((node = mmap(NULL, size + 2 * GUARDPAGE_SIZE, PROT_NONE, + MAP_PRIVATE|MAP_ANON, -1, 0)) == MAP_FAILED) +#elif APR_ALLOCATOR_USES_MMAP if ((node = mmap(NULL, size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0)) == MAP_FAILED) #else @@ -355,6 +373,13 @@ apr_memnode_t *allocator_alloc(apr_allocator_t *allocator, apr_size_t in_size) #endif return NULL; +#if APR_ALLOCATOR_GUARD_PAGES + node = (apr_memnode_t *)((char *)node + GUARDPAGE_SIZE); + if (mprotect(node, size, PROT_READ|PROT_WRITE) != 0) { + munmap((char *)node - GUARDPAGE_SIZE, size + 2 * GUARDPAGE_SIZE); + return NULL; + } +#endif node->index = index; node->endp = (char *)node + size; @@ -437,7 +462,8 @@ void allocator_free(apr_allocator_t *allocator, apr_memnode_t *node) node = freelist; freelist = node->next; #if APR_ALLOCATOR_USES_MMAP - munmap(node, (node->index+1) << BOUNDARY_INDEX); + munmap((char *)node - GUARDPAGE_SIZE, + 2 * GUARDPAGE_SIZE + ((node->index+1) << BOUNDARY_INDEX)); #else free(node); #endif |