crypto/rsa/rsa_ssl.c

   1 /*
   2  * Copyright 1995-2017 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the OpenSSL license (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/bn.h>
  13 #include <openssl/rsa.h>
  14 #include <openssl/rand.h>
  15
  16 int RSA_padding_add_SSLv23(unsigned char *to, int tlen,
  17                            const unsigned char *from, int flen)
  18 {
  19     int i, j;
  20     unsigned char *p;
  21
  22     if (flen > (tlen - 11)) {
  23         RSAerr(RSA_F_RSA_PADDING_ADD_SSLV23,
  24                RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
  25         return 0;
  26     }
  27
  28     p = (unsigned char *)to;
  29
  30     *(p++) = 0;
  31     *(p++) = 2;                 /* Public Key BT (Block Type) */
  32
  33     /* pad out with non-zero random data */
  34     j = tlen - 3 - 8 - flen;
  35
  36     if (RAND_bytes(p, j) <= 0)
  37         return 0;
  38     for (i = 0; i < j; i++) {
  39         if (*p == '\0')
  40             do {
  41                 if (RAND_bytes(p, 1) <= 0)
  42                     return 0;
  43             } while (*p == '\0');
  44         p++;
  45     }
  46
  47     memset(p, 3, 8);
  48     p += 8;
  49     *(p++) = '\0';
  50
  51     memcpy(p, from, (unsigned int)flen);
  52     return 1;
  53 }
  54
  55 int RSA_padding_check_SSLv23(unsigned char *to, int tlen,
  56                              const unsigned char *from, int flen, int num)
  57 {
  58     int i, j, k;
  59     const unsigned char *p;
  60
  61     p = from;
  62     if (flen < 10) {
  63         RSAerr(RSA_F_RSA_PADDING_CHECK_SSLV23, RSA_R_DATA_TOO_SMALL);
  64         return -1;
  65     }
  66     /* Accept even zero-padded input */
  67     if (flen == num) {
  68         if (*(p++) != 0) {
  69             RSAerr(RSA_F_RSA_PADDING_CHECK_SSLV23, RSA_R_BLOCK_TYPE_IS_NOT_02);
  70             return -1;
  71         }
  72         flen--;
  73     }
  74     if ((num != (flen + 1)) || (*(p++) != 02)) {
  75         RSAerr(RSA_F_RSA_PADDING_CHECK_SSLV23, RSA_R_BLOCK_TYPE_IS_NOT_02);
  76         return -1;
  77     }
  78
  79     /* scan over padding data */
  80     j = flen - 1;               /* one for type */
  81     for (i = 0; i < j; i++)
  82         if (*(p++) == 0)
  83             break;
  84
  85     if ((i == j) || (i < 8)) {
  86         RSAerr(RSA_F_RSA_PADDING_CHECK_SSLV23,
  87                RSA_R_NULL_BEFORE_BLOCK_MISSING);
  88         return -1;
  89     }
  90     for (k = -9; k < -1; k++) {
  91         if (p[k] != 0x03)
  92             break;
  93     }
  94     if (k == -1) {
  95         RSAerr(RSA_F_RSA_PADDING_CHECK_SSLV23, RSA_R_SSLV3_ROLLBACK_ATTACK);
  96         return -1;
  97     }
  98
  99     i++;                        /* Skip over the '\0' */
 100     j -= i;
 101     if (j > tlen) {
 102         RSAerr(RSA_F_RSA_PADDING_CHECK_SSLV23, RSA_R_DATA_TOO_LARGE);
 103         return -1;
 104     }
 105     memcpy(to, p, (unsigned int)j);
 106
 107     return j;
 108 }