mirror of
https://github.com/GrapheneOS/hardened_malloc.git
synced 2024-12-26 07:59:25 -05:00
dcd969ae04
The stdint.h types don't cover 128-bit integers and the underscore makes them ill suited to usage in function suffixes. Instead, use the common naming style in the Linux kernel and elsewhere including the ChaCha8 implementation included here.
82 lines
2.2 KiB
C
82 lines
2.2 KiB
C
#include <errno.h>
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#include "memory.h"
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#include "pages.h"
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#include "util.h"
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#define ALIGNMENT_CEILING(s, alignment) (((s) + (alignment - 1)) & ((~(alignment)) + 1))
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void *allocate_pages(size_t usable_size, size_t guard_size, bool unprotect) {
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size_t real_size;
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if (unlikely(__builtin_add_overflow(usable_size, guard_size * 2, &real_size))) {
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errno = ENOMEM;
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return NULL;
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}
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void *real = memory_map(real_size);
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if (unlikely(real == NULL)) {
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return NULL;
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}
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void *usable = (char *)real + guard_size;
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if (unprotect && unlikely(memory_protect_rw(usable, usable_size))) {
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memory_unmap(real, real_size);
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return NULL;
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}
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return usable;
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}
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void deallocate_pages(void *usable, size_t usable_size, size_t guard_size) {
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memory_unmap((char *)usable - guard_size, usable_size + guard_size * 2);
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}
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void *allocate_pages_aligned(size_t usable_size, size_t alignment, size_t guard_size) {
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usable_size = PAGE_CEILING(usable_size);
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if (unlikely(!usable_size)) {
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errno = ENOMEM;
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return NULL;
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}
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size_t alloc_size;
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if (unlikely(__builtin_add_overflow(usable_size, alignment - PAGE_SIZE, &alloc_size))) {
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errno = ENOMEM;
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return NULL;
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}
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size_t real_alloc_size;
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if (unlikely(__builtin_add_overflow(alloc_size, guard_size * 2, &real_alloc_size))) {
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errno = ENOMEM;
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return NULL;
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}
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void *real = memory_map(real_alloc_size);
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if (unlikely(real == NULL)) {
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return NULL;
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}
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void *usable = (char *)real + guard_size;
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size_t lead_size = ALIGNMENT_CEILING((uintptr_t)usable, alignment) - (uintptr_t)usable;
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size_t trail_size = alloc_size - lead_size - usable_size;
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void *base = (char *)usable + lead_size;
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if (unlikely(memory_protect_rw(base, usable_size))) {
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memory_unmap(real, real_alloc_size);
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return NULL;
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}
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if (lead_size) {
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if (unlikely(memory_unmap(real, lead_size))) {
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memory_unmap(real, real_alloc_size);
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return NULL;
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}
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}
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if (trail_size) {
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if (unlikely(memory_unmap((char *)base + usable_size + guard_size, trail_size))) {
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memory_unmap(real, real_alloc_size);
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return NULL;
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}
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}
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return base;
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}
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