crypto/buffer/buffer.c

   1 /*
   2  * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the Apache License 2.0 (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #include <stdio.h>
  11 #include "internal/cryptlib.h"
  12 #include <openssl/buffer.h>
  13
  14 /*
  15  * LIMIT_BEFORE_EXPANSION is the maximum n such that (n+3)/3*4 < 2**31. That
  16  * function is applied in several functions in this file and this limit
  17  * ensures that the result fits in an int.
  18  */
  19 #define LIMIT_BEFORE_EXPANSION 0x5ffffffc
  20
  21 BUF_MEM *BUF_MEM_new_ex(unsigned long flags)
  22 {
  23     BUF_MEM *ret;
  24
  25     ret = BUF_MEM_new();
  26     if (ret != NULL)
  27         ret->flags = flags;
  28     return ret;
  29 }
  30
  31 BUF_MEM *BUF_MEM_new(void)
  32 {
  33     BUF_MEM *ret;
  34
  35     ret = OPENSSL_zalloc(sizeof(*ret));
  36     if (ret == NULL) {
  37         BUFerr(BUF_F_BUF_MEM_NEW, ERR_R_MALLOC_FAILURE);
  38         return NULL;
  39     }
  40     return ret;
  41 }
  42
  43 void BUF_MEM_free(BUF_MEM *a)
  44 {
  45     if (a == NULL)
  46         return;
  47     if (a->data != NULL) {
  48         if (a->flags & BUF_MEM_FLAG_SECURE)
  49             OPENSSL_secure_clear_free(a->data, a->max);
  50         else
  51             OPENSSL_clear_free(a->data, a->max);
  52     }
  53     OPENSSL_free(a);
  54 }
  55
  56 /* Allocate a block of secure memory; copy over old data if there
  57  * was any, and then free it. */
  58 static char *sec_alloc_realloc(BUF_MEM *str, size_t len)
  59 {
  60     char *ret;
  61
  62     ret = OPENSSL_secure_malloc(len);
  63     if (str->data != NULL) {
  64         if (ret != NULL) {
  65             memcpy(ret, str->data, str->length);
  66             OPENSSL_secure_clear_free(str->data, str->length);
  67             str->data = NULL;
  68         }
  69     }
  70     return ret;
  71 }
  72
  73 size_t BUF_MEM_grow(BUF_MEM *str, size_t len)
  74 {
  75     char *ret;
  76     size_t n;
  77
  78     if (str->length >= len) {
  79         str->length = len;
  80         return len;
  81     }
  82     if (str->max >= len) {
  83         if (str->data != NULL)
  84             memset(&str->data[str->length], 0, len - str->length);
  85         str->length = len;
  86         return len;
  87     }
  88     /* This limit is sufficient to ensure (len+3)/3*4 < 2**31 */
  89     if (len > LIMIT_BEFORE_EXPANSION) {
  90         BUFerr(BUF_F_BUF_MEM_GROW, ERR_R_MALLOC_FAILURE);
  91         return 0;
  92     }
  93     n = (len + 3) / 3 * 4;
  94     if ((str->flags & BUF_MEM_FLAG_SECURE))
  95         ret = sec_alloc_realloc(str, n);
  96     else
  97         ret = OPENSSL_realloc(str->data, n);
  98     if (ret == NULL) {
  99         BUFerr(BUF_F_BUF_MEM_GROW, ERR_R_MALLOC_FAILURE);
 100         len = 0;
 101     } else {
 102         str->data = ret;
 103         str->max = n;
 104         memset(&str->data[str->length], 0, len - str->length);
 105         str->length = len;
 106     }
 107     return len;
 108 }
 109
 110 size_t BUF_MEM_grow_clean(BUF_MEM *str, size_t len)
 111 {
 112     char *ret;
 113     size_t n;
 114
 115     if (str->length >= len) {
 116         if (str->data != NULL)
 117             memset(&str->data[len], 0, str->length - len);
 118         str->length = len;
 119         return len;
 120     }
 121     if (str->max >= len) {
 122         memset(&str->data[str->length], 0, len - str->length);
 123         str->length = len;
 124         return len;
 125     }
 126     /* This limit is sufficient to ensure (len+3)/3*4 < 2**31 */
 127     if (len > LIMIT_BEFORE_EXPANSION) {
 128         BUFerr(BUF_F_BUF_MEM_GROW_CLEAN, ERR_R_MALLOC_FAILURE);
 129         return 0;
 130     }
 131     n = (len + 3) / 3 * 4;
 132     if ((str->flags & BUF_MEM_FLAG_SECURE))
 133         ret = sec_alloc_realloc(str, n);
 134     else
 135         ret = OPENSSL_clear_realloc(str->data, str->max, n);
 136     if (ret == NULL) {
 137         BUFerr(BUF_F_BUF_MEM_GROW_CLEAN, ERR_R_MALLOC_FAILURE);
 138         len = 0;
 139     } else {
 140         str->data = ret;
 141         str->max = n;
 142         memset(&str->data[str->length], 0, len - str->length);
 143         str->length = len;
 144     }
 145     return len;
 146 }
 147
 148 void BUF_reverse(unsigned char *out, const unsigned char *in, size_t size)
 149 {
 150     size_t i;
 151     if (in) {
 152         out += size - 1;
 153         for (i = 0; i < size; i++)
 154             *out-- = *in++;
 155     } else {
 156         unsigned char *q;
 157         char c;
 158         q = out + size - 1;
 159         for (i = 0; i < size / 2; i++) {
 160             c = *q;
 161             *q-- = *out;
 162             *out++ = c;
 163         }
 164     }
 165 }