emo/hardened_malloc
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wrap more memory mapping implementation details

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This commit is contained in:
Daniel Micay 2018-08-29 10:52:10 -04:00
parent 1cb28531a8
commit d779d41721
3 changed files with 17 additions and 9 deletions
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13
malloc.c
View File

@ -8,7 +8,6 @@
#include <unistd.h> #include <unistd.h>
#include <pthread.h> #include <pthread.h>
#include <sys/mman.h>
#include <malloc.h> #include <malloc.h>
@ -40,7 +39,7 @@ static void *allocate_pages(size_t usable_size, size_t guard_size, bool unprotec
return NULL; return NULL;
} }
void *usable = (char *)real + guard_size; void *usable = (char *)real + guard_size;
if (unprotect && memory_protect(usable, usable_size, PROT_READ|PROT_WRITE)) { if (unprotect && memory_protect_rw(usable, usable_size)) {
memory_unmap(real, real_size); memory_unmap(real, real_size);
return NULL; return NULL;
} }
@ -81,7 +80,7 @@ static void *allocate_pages_aligned(size_t usable_size, size_t alignment, size_t
size_t trail_size = alloc_size - lead_size - usable_size; size_t trail_size = alloc_size - lead_size - usable_size;
void *base = (char *)usable + lead_size; void *base = (char *)usable + lead_size;
if (memory_protect(base, usable_size, PROT_READ|PROT_WRITE)) { if (memory_protect_rw(base, usable_size)) {
memory_unmap(real, real_alloc_size); memory_unmap(real, real_alloc_size);
return NULL; return NULL;
} }
@ -203,7 +202,7 @@ static struct slab_metadata *alloc_metadata(struct size_class *c, size_t slab_si
if (allocate > metadata_max) { if (allocate > metadata_max) {
allocate = metadata_max; allocate = metadata_max;
} }
if (memory_protect(c->slab_info, allocate * sizeof(struct slab_metadata), PROT_READ|PROT_WRITE)) { if (memory_protect_rw(c->slab_info, allocate * sizeof(struct slab_metadata))) {
return NULL; return NULL;
} }
c->metadata_allocated = allocate; c->metadata_allocated = allocate;
@ -333,7 +332,7 @@ static inline void *slab_allocate(size_t requested_size) {
} }
void *slab = get_slab(c, slab_size, metadata); void *slab = get_slab(c, slab_size, metadata);
if (requested_size != 0 && memory_protect(slab, slab_size, PROT_READ|PROT_WRITE)) { if (requested_size != 0 && memory_protect_rw(slab, slab_size)) {
c->metadata_count--; c->metadata_count--;
pthread_mutex_unlock(&c->mutex); pthread_mutex_unlock(&c->mutex);
return NULL; return NULL;
@ -636,14 +635,14 @@ COLD static void init_slow_path(void) {
fatal_error("failed to allocate slab metadata"); fatal_error("failed to allocate slab metadata");
} }
c->metadata_allocated = PAGE_SIZE / sizeof(struct slab_metadata); c->metadata_allocated = PAGE_SIZE / sizeof(struct slab_metadata);
if (memory_protect(c->slab_info, c->metadata_allocated * sizeof(struct slab_metadata), PROT_READ|PROT_WRITE)) { if (memory_protect_rw(c->slab_info, c->metadata_allocated * sizeof(struct slab_metadata))) {
fatal_error("failed to allocate initial slab info"); fatal_error("failed to allocate initial slab info");
} }
} }
atomic_store_explicit(&ro.initialized, true, memory_order_release); atomic_store_explicit(&ro.initialized, true, memory_order_release);
if (memory_protect(&ro, sizeof(ro), PROT_READ)) { if (memory_protect_ro(&ro, sizeof(ro))) {
fatal_error("failed to protect allocator data"); fatal_error("failed to protect allocator data");
} }

10
memory.c
View File

@ -24,7 +24,7 @@ int memory_unmap(void *ptr, size_t size) {
return ret; return ret;
} }
int memory_protect(void *ptr, size_t size, int prot) { static int memory_protect_prot(void *ptr, size_t size, int prot) {
int ret = mprotect(ptr, size, prot); int ret = mprotect(ptr, size, prot);
if (unlikely(ret) && errno != ENOMEM) { if (unlikely(ret) && errno != ENOMEM) {
fatal_error("non-ENOMEM mprotect failure"); fatal_error("non-ENOMEM mprotect failure");
@ -32,6 +32,14 @@ int memory_protect(void *ptr, size_t size, int prot) {
return ret; return ret;
} }
int memory_protect_rw(void *ptr, size_t size) {
return memory_protect_prot(ptr, size, PROT_READ|PROT_WRITE);
}
int memory_protect_ro(void *ptr, size_t size) {
return memory_protect_prot(ptr, size, PROT_READ);
}
int memory_remap_fixed(void *old, size_t old_size, void *new, size_t new_size) { int memory_remap_fixed(void *old, size_t old_size, void *new, size_t new_size) {
void *ptr = mremap(old, old_size, new_size, MREMAP_MAYMOVE|MREMAP_FIXED, new); void *ptr = mremap(old, old_size, new_size, MREMAP_MAYMOVE|MREMAP_FIXED, new);
if (unlikely(ptr == MAP_FAILED)) { if (unlikely(ptr == MAP_FAILED)) {

3
memory.h
View File

@ -5,7 +5,8 @@
void *memory_map(size_t size); void *memory_map(size_t size);
int memory_unmap(void *ptr, size_t size); int memory_unmap(void *ptr, size_t size);
int memory_protect(void *ptr, size_t size, int prot); int memory_protect_rw(void *ptr, size_t size);
int memory_protect_ro(void *ptr, size_t size);
int memory_remap_fixed(void *old, size_t old_size, void *new, size_t new_size); int memory_remap_fixed(void *old, size_t old_size, void *new, size_t new_size);
#endif #endif