/* * Buffer-based memory allocator * * Copyright The Mbed TLS Contributors * SPDX-License-Identifier: Apache-2.0 * * Licensed under the Apache License, Version 2.0 (the "License"); you may * not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #include "common.h" #if defined(MBEDTLS_MEMORY_BUFFER_ALLOC_C) #include "mbedtls/memory_buffer_alloc.h" /* No need for the header guard as MBEDTLS_MEMORY_BUFFER_ALLOC_C is dependent upon MBEDTLS_PLATFORM_C */ #include "mbedtls/platform.h" #include "mbedtls/platform_util.h" #include <string.h> #if defined(MBEDTLS_MEMORY_BACKTRACE) #include <execinfo.h> #endif #if defined(MBEDTLS_THREADING_C) #include "mbedtls/threading.h" #endif #define MAGIC1 0xFF00AA55 #define MAGIC2 0xEE119966 #define MAX_BT 20 typedef struct _memory_header memory_header; struct _memory_header { size_t magic1; size_t size; size_t alloc; memory_header *prev; memory_header *next; memory_header *prev_free; memory_header *next_free; #if defined(MBEDTLS_MEMORY_BACKTRACE) char **trace; size_t trace_count; #endif size_t magic2; }; typedef struct { unsigned char *buf; size_t len; memory_header *first; memory_header *first_free; int verify; #if defined(MBEDTLS_MEMORY_DEBUG) size_t alloc_count; size_t free_count; size_t total_used; size_t maximum_used; size_t header_count; size_t maximum_header_count; #endif #if defined(MBEDTLS_THREADING_C) mbedtls_threading_mutex_t mutex; #endif } buffer_alloc_ctx; static buffer_alloc_ctx heap; #if defined(MBEDTLS_MEMORY_DEBUG) static void debug_header( memory_header *hdr ) { #if defined(MBEDTLS_MEMORY_BACKTRACE) size_t i; #endif mbedtls_fprintf( stderr, "HDR: PTR(%10zu), PREV(%10zu), NEXT(%10zu), " "ALLOC(%zu), SIZE(%10zu)\n", (size_t) hdr, (size_t) hdr->prev, (size_t) hdr->next, hdr->alloc, hdr->size ); mbedtls_fprintf( stderr, " FPREV(%10zu), FNEXT(%10zu)\n", (size_t) hdr->prev_free, (size_t) hdr->next_free ); #if defined(MBEDTLS_MEMORY_BACKTRACE) mbedtls_fprintf( stderr, "TRACE: \n" ); for( i = 0; i < hdr->trace_count; i++ ) mbedtls_fprintf( stderr, "%s\n", hdr->trace[i] ); mbedtls_fprintf( stderr, "\n" ); #endif } static void debug_chain( void ) { memory_header *cur = heap.first; mbedtls_fprintf( stderr, "\nBlock list\n" ); while( cur != NULL ) { debug_header( cur ); cur = cur->next; } mbedtls_fprintf( stderr, "Free list\n" ); cur = heap.first_free; while( cur != NULL ) { debug_header( cur ); cur = cur->next_free; } } #endif /* MBEDTLS_MEMORY_DEBUG */ static int verify_header( memory_header *hdr ) { if( hdr->magic1 != MAGIC1 ) { #if defined(MBEDTLS_MEMORY_DEBUG) mbedtls_fprintf( stderr, "FATAL: MAGIC1 mismatch\n" ); #endif return( 1 ); } if( hdr->magic2 != MAGIC2 ) { #if defined(MBEDTLS_MEMORY_DEBUG) mbedtls_fprintf( stderr, "FATAL: MAGIC2 mismatch\n" ); #endif return( 1 ); } if( hdr->alloc > 1 ) { #if defined(MBEDTLS_MEMORY_DEBUG) mbedtls_fprintf( stderr, "FATAL: alloc has illegal value\n" ); #endif return( 1 ); } if( hdr->prev != NULL && hdr->prev == hdr->next ) { #if defined(MBEDTLS_MEMORY_DEBUG) mbedtls_fprintf( stderr, "FATAL: prev == next\n" ); #endif return( 1 ); } if( hdr->prev_free != NULL && hdr->prev_free == hdr->next_free ) { #if defined(MBEDTLS_MEMORY_DEBUG) mbedtls_fprintf( stderr, "FATAL: prev_free == next_free\n" ); #endif return( 1 ); } return( 0 ); } static int verify_chain( void ) { memory_header *prv = heap.first, *cur; if( prv == NULL || verify_header( prv ) != 0 ) { #if defined(MBEDTLS_MEMORY_DEBUG) mbedtls_fprintf( stderr, "FATAL: verification of first header " "failed\n" ); #endif return( 1 ); } if( heap.first->prev != NULL ) { #if defined(MBEDTLS_MEMORY_DEBUG) mbedtls_fprintf( stderr, "FATAL: verification failed: " "first->prev != NULL\n" ); #endif return( 1 ); } cur = heap.first->next; while( cur != NULL ) { if( verify_header( cur ) != 0 ) { #if defined(MBEDTLS_MEMORY_DEBUG) mbedtls_fprintf( stderr, "FATAL: verification of header " "failed\n" ); #endif return( 1 ); } if( cur->prev != prv ) { #if defined(MBEDTLS_MEMORY_DEBUG) mbedtls_fprintf( stderr, "FATAL: verification failed: " "cur->prev != prv\n" ); #endif return( 1 ); } prv = cur; cur = cur->next; } return( 0 ); } static void *buffer_alloc_calloc( size_t n, size_t size ) { memory_header *new, *cur = heap.first_free; unsigned char *p; void *ret; size_t original_len, len; #if defined(MBEDTLS_MEMORY_BACKTRACE) void *trace_buffer[MAX_BT]; size_t trace_cnt; #endif if( heap.buf == NULL || heap.first == NULL ) return( NULL ); original_len = len = n * size; if( n == 0 || size == 0 || len / n != size ) return( NULL ); else if( len > (size_t)-MBEDTLS_MEMORY_ALIGN_MULTIPLE ) return( NULL ); if( len % MBEDTLS_MEMORY_ALIGN_MULTIPLE ) { len -= len % MBEDTLS_MEMORY_ALIGN_MULTIPLE; len += MBEDTLS_MEMORY_ALIGN_MULTIPLE; } // Find block that fits // while( cur != NULL ) { if( cur->size >= len ) break; cur = cur->next_free; } if( cur == NULL ) return( NULL ); if( cur->alloc != 0 ) { #if defined(MBEDTLS_MEMORY_DEBUG) mbedtls_fprintf( stderr, "FATAL: block in free_list but allocated " "data\n" ); #endif mbedtls_exit( 1 ); } #if defined(MBEDTLS_MEMORY_DEBUG) heap.alloc_count++; #endif // Found location, split block if > memory_header + 4 room left // if( cur->size - len < sizeof(memory_header) + MBEDTLS_MEMORY_ALIGN_MULTIPLE ) { cur->alloc = 1; // Remove from free_list // if( cur->prev_free != NULL ) cur->prev_free->next_free = cur->next_free; else heap.first_free = cur->next_free; if( cur->next_free != NULL ) cur->next_free->prev_free = cur->prev_free; cur->prev_free = NULL; cur->next_free = NULL; #if defined(MBEDTLS_MEMORY_DEBUG) heap.total_used += cur->size; if( heap.total_used > heap.maximum_used ) heap.maximum_used = heap.total_used; #endif #if defined(MBEDTLS_MEMORY_BACKTRACE) trace_cnt = backtrace( trace_buffer, MAX_BT ); cur->trace = backtrace_symbols( trace_buffer, trace_cnt ); cur->trace_count = trace_cnt; #endif if( ( heap.verify & MBEDTLS_MEMORY_VERIFY_ALLOC ) && verify_chain() != 0 ) mbedtls_exit( 1 ); ret = (unsigned char *) cur + sizeof( memory_header ); memset( ret, 0, original_len ); return( ret ); } p = ( (unsigned char *) cur ) + sizeof(memory_header) + len; new = (memory_header *) p; new->size = cur->size - len - sizeof(memory_header); new->alloc = 0; new->prev = cur; new->next = cur->next; #if defined(MBEDTLS_MEMORY_BACKTRACE) new->trace = NULL; new->trace_count = 0; #endif new->magic1 = MAGIC1; new->magic2 = MAGIC2; if( new->next != NULL ) new->next->prev = new; // Replace cur with new in free_list // new->prev_free = cur->prev_free; new->next_free = cur->next_free; if( new->prev_free != NULL ) new->prev_free->next_free = new; else heap.first_free = new; if( new->next_free != NULL ) new->next_free->prev_free = new; cur->alloc = 1; cur->size = len; cur->next = new; cur->prev_free = NULL; cur->next_free = NULL; #if defined(MBEDTLS_MEMORY_DEBUG) heap.header_count++; if( heap.header_count > heap.maximum_header_count ) heap.maximum_header_count = heap.header_count; heap.total_used += cur->size; if( heap.total_used > heap.maximum_used ) heap.maximum_used = heap.total_used; #endif #if defined(MBEDTLS_MEMORY_BACKTRACE) trace_cnt = backtrace( trace_buffer, MAX_BT ); cur->trace = backtrace_symbols( trace_buffer, trace_cnt ); cur->trace_count = trace_cnt; #endif if( ( heap.verify & MBEDTLS_MEMORY_VERIFY_ALLOC ) && verify_chain() != 0 ) mbedtls_exit( 1 ); ret = (unsigned char *) cur + sizeof( memory_header ); memset( ret, 0, original_len ); return( ret ); } static void buffer_alloc_free( void *ptr ) { memory_header *hdr, *old = NULL; unsigned char *p = (unsigned char *) ptr; if( ptr == NULL || heap.buf == NULL || heap.first == NULL ) return; if( p < heap.buf || p >= heap.buf + heap.len ) { #if defined(MBEDTLS_MEMORY_DEBUG) mbedtls_fprintf( stderr, "FATAL: mbedtls_free() outside of managed " "space\n" ); #endif mbedtls_exit( 1 ); } p -= sizeof(memory_header); hdr = (memory_header *) p; if( verify_header( hdr ) != 0 ) mbedtls_exit( 1 ); if( hdr->alloc != 1 ) { #if defined(MBEDTLS_MEMORY_DEBUG) mbedtls_fprintf( stderr, "FATAL: mbedtls_free() on unallocated " "data\n" ); #endif mbedtls_exit( 1 ); } hdr->alloc = 0; #if defined(MBEDTLS_MEMORY_DEBUG) heap.free_count++; heap.total_used -= hdr->size; #endif #if defined(MBEDTLS_MEMORY_BACKTRACE) free( hdr->trace ); hdr->trace = NULL; hdr->trace_count = 0; #endif // Regroup with block before // if( hdr->prev != NULL && hdr->prev->alloc == 0 ) { #if defined(MBEDTLS_MEMORY_DEBUG) heap.header_count--; #endif hdr->prev->size += sizeof(memory_header) + hdr->size; hdr->prev->next = hdr->next; old = hdr; hdr = hdr->prev; if( hdr->next != NULL ) hdr->next->prev = hdr; memset( old, 0, sizeof(memory_header) ); } // Regroup with block after // if( hdr->next != NULL && hdr->next->alloc == 0 ) { #if defined(MBEDTLS_MEMORY_DEBUG) heap.header_count--; #endif hdr->size += sizeof(memory_header) + hdr->next->size; old = hdr->next; hdr->next = hdr->next->next; if( hdr->prev_free != NULL || hdr->next_free != NULL ) { if( hdr->prev_free != NULL ) hdr->prev_free->next_free = hdr->next_free; else heap.first_free = hdr->next_free; if( hdr->next_free != NULL ) hdr->next_free->prev_free = hdr->prev_free; } hdr->prev_free = old->prev_free; hdr->next_free = old->next_free; if( hdr->prev_free != NULL ) hdr->prev_free->next_free = hdr; else heap.first_free = hdr; if( hdr->next_free != NULL ) hdr->next_free->prev_free = hdr; if( hdr->next != NULL ) hdr->next->prev = hdr; memset( old, 0, sizeof(memory_header) ); } // Prepend to free_list if we have not merged // (Does not have to stay in same order as prev / next list) // if( old == NULL ) { hdr->next_free = heap.first_free; if( heap.first_free != NULL ) heap.first_free->prev_free = hdr; heap.first_free = hdr; } if( ( heap.verify & MBEDTLS_MEMORY_VERIFY_FREE ) && verify_chain() != 0 ) mbedtls_exit( 1 ); } void mbedtls_memory_buffer_set_verify( int verify ) { heap.verify = verify; } int mbedtls_memory_buffer_alloc_verify( void ) { return verify_chain(); } #if defined(MBEDTLS_MEMORY_DEBUG) void mbedtls_memory_buffer_alloc_status( void ) { mbedtls_fprintf( stderr, "Current use: %zu blocks / %zu bytes, max: %zu blocks / " "%zu bytes (total %zu bytes), alloc / free: %zu / %zu\n", heap.header_count, heap.total_used, heap.maximum_header_count, heap.maximum_used, heap.maximum_header_count * sizeof( memory_header ) + heap.maximum_used, heap.alloc_count, heap.free_count ); if( heap.first->next == NULL ) { mbedtls_fprintf( stderr, "All memory de-allocated in stack buffer\n" ); } else { mbedtls_fprintf( stderr, "Memory currently allocated:\n" ); debug_chain(); } } void mbedtls_memory_buffer_alloc_max_get( size_t *max_used, size_t *max_blocks ) { *max_used = heap.maximum_used; *max_blocks = heap.maximum_header_count; } void mbedtls_memory_buffer_alloc_max_reset( void ) { heap.maximum_used = 0; heap.maximum_header_count = 0; } void mbedtls_memory_buffer_alloc_cur_get( size_t *cur_used, size_t *cur_blocks ) { *cur_used = heap.total_used; *cur_blocks = heap.header_count; } #endif /* MBEDTLS_MEMORY_DEBUG */ #if defined(MBEDTLS_THREADING_C) static void *buffer_alloc_calloc_mutexed( size_t n, size_t size ) { void *buf; if( mbedtls_mutex_lock( &heap.mutex ) != 0 ) return( NULL ); buf = buffer_alloc_calloc( n, size ); if( mbedtls_mutex_unlock( &heap.mutex ) ) return( NULL ); return( buf ); } static void buffer_alloc_free_mutexed( void *ptr ) { /* We have no good option here, but corrupting the heap seems * worse than losing memory. */ if( mbedtls_mutex_lock( &heap.mutex ) ) return; buffer_alloc_free( ptr ); (void) mbedtls_mutex_unlock( &heap.mutex ); } #endif /* MBEDTLS_THREADING_C */ void mbedtls_memory_buffer_alloc_init( unsigned char *buf, size_t len ) { memset( &heap, 0, sizeof( buffer_alloc_ctx ) ); #if defined(MBEDTLS_THREADING_C) mbedtls_mutex_init( &heap.mutex ); mbedtls_platform_set_calloc_free( buffer_alloc_calloc_mutexed, buffer_alloc_free_mutexed ); #else mbedtls_platform_set_calloc_free( buffer_alloc_calloc, buffer_alloc_free ); #endif if( len < sizeof( memory_header ) + MBEDTLS_MEMORY_ALIGN_MULTIPLE ) return; else if( (size_t)buf % MBEDTLS_MEMORY_ALIGN_MULTIPLE ) { /* Adjust len first since buf is used in the computation */ len -= MBEDTLS_MEMORY_ALIGN_MULTIPLE - (size_t)buf % MBEDTLS_MEMORY_ALIGN_MULTIPLE; buf += MBEDTLS_MEMORY_ALIGN_MULTIPLE - (size_t)buf % MBEDTLS_MEMORY_ALIGN_MULTIPLE; } memset( buf, 0, len ); heap.buf = buf; heap.len = len; heap.first = (memory_header *)buf; heap.first->size = len - sizeof( memory_header ); heap.first->magic1 = MAGIC1; heap.first->magic2 = MAGIC2; heap.first_free = heap.first; } void mbedtls_memory_buffer_alloc_free( void ) { #if defined(MBEDTLS_THREADING_C) mbedtls_mutex_free( &heap.mutex ); #endif mbedtls_platform_zeroize( &heap, sizeof(buffer_alloc_ctx) ); } #if defined(MBEDTLS_SELF_TEST) static int check_pointer( void *p ) { if( p == NULL ) return( -1 ); if( (size_t) p % MBEDTLS_MEMORY_ALIGN_MULTIPLE != 0 ) return( -1 ); return( 0 ); } static int check_all_free( void ) { if( #if defined(MBEDTLS_MEMORY_DEBUG) heap.total_used != 0 || #endif heap.first != heap.first_free || (void *) heap.first != (void *) heap.buf ) { return( -1 ); } return( 0 ); } #define TEST_ASSERT( condition ) \ if( ! (condition) ) \ { \ if( verbose != 0 ) \ mbedtls_printf( "failed\n" ); \ \ ret = 1; \ goto cleanup; \ } int mbedtls_memory_buffer_alloc_self_test( int verbose ) { unsigned char buf[1024]; unsigned char *p, *q, *r, *end; int ret = 0; if( verbose != 0 ) mbedtls_printf( " MBA test #1 (basic alloc-free cycle): " ); mbedtls_memory_buffer_alloc_init( buf, sizeof( buf ) ); p = mbedtls_calloc( 1, 1 ); q = mbedtls_calloc( 1, 128 ); r = mbedtls_calloc( 1, 16 ); TEST_ASSERT( check_pointer( p ) == 0 && check_pointer( q ) == 0 && check_pointer( r ) == 0 ); mbedtls_free( r ); mbedtls_free( q ); mbedtls_free( p ); TEST_ASSERT( check_all_free( ) == 0 ); /* Memorize end to compare with the next test */ end = heap.buf + heap.len; mbedtls_memory_buffer_alloc_free( ); if( verbose != 0 ) mbedtls_printf( "passed\n" ); if( verbose != 0 ) mbedtls_printf( " MBA test #2 (buf not aligned): " ); mbedtls_memory_buffer_alloc_init( buf + 1, sizeof( buf ) - 1 ); TEST_ASSERT( heap.buf + heap.len == end ); p = mbedtls_calloc( 1, 1 ); q = mbedtls_calloc( 1, 128 ); r = mbedtls_calloc( 1, 16 ); TEST_ASSERT( check_pointer( p ) == 0 && check_pointer( q ) == 0 && check_pointer( r ) == 0 ); mbedtls_free( r ); mbedtls_free( q ); mbedtls_free( p ); TEST_ASSERT( check_all_free( ) == 0 ); mbedtls_memory_buffer_alloc_free( ); if( verbose != 0 ) mbedtls_printf( "passed\n" ); if( verbose != 0 ) mbedtls_printf( " MBA test #3 (full): " ); mbedtls_memory_buffer_alloc_init( buf, sizeof( buf ) ); p = mbedtls_calloc( 1, sizeof( buf ) - sizeof( memory_header ) ); TEST_ASSERT( check_pointer( p ) == 0 ); TEST_ASSERT( mbedtls_calloc( 1, 1 ) == NULL ); mbedtls_free( p ); p = mbedtls_calloc( 1, sizeof( buf ) - 2 * sizeof( memory_header ) - 16 ); q = mbedtls_calloc( 1, 16 ); TEST_ASSERT( check_pointer( p ) == 0 && check_pointer( q ) == 0 ); TEST_ASSERT( mbedtls_calloc( 1, 1 ) == NULL ); mbedtls_free( q ); TEST_ASSERT( mbedtls_calloc( 1, 17 ) == NULL ); mbedtls_free( p ); TEST_ASSERT( check_all_free( ) == 0 ); mbedtls_memory_buffer_alloc_free( ); if( verbose != 0 ) mbedtls_printf( "passed\n" ); cleanup: mbedtls_memory_buffer_alloc_free( ); return( ret ); } #endif /* MBEDTLS_SELF_TEST */ #endif /* MBEDTLS_MEMORY_BUFFER_ALLOC_C */