1 /* 2 * Copyright (c) 2016, 2017 Joel Sing <jsing@openbsd.org> 3 * 4 * Permission to use, copy, modify, and distribute this software for any 5 * purpose with or without fee is hereby granted, provided that the above 6 * copyright notice and this permission notice appear in all copies. 7 * 8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 11 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 13 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 14 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 15 */ 16 17 #include "ssl_locl.h" 18 19 static int 20 ssl_clamp_version_range(uint16_t *min_ver, uint16_t *max_ver, 21 uint16_t clamp_min, uint16_t clamp_max) 22 { 23 if (clamp_min > clamp_max || *min_ver > *max_ver) 24 return 0; 25 if (clamp_max < *min_ver || clamp_min > *max_ver) 26 return 0; 27 28 if (*min_ver < clamp_min) 29 *min_ver = clamp_min; 30 if (*max_ver > clamp_max) 31 *max_ver = clamp_max; 32 33 return 1; 34 } 35 36 int 37 ssl_enabled_version_range(SSL *s, uint16_t *min_ver, uint16_t *max_ver) 38 { 39 uint16_t min_version, max_version; 40 41 /* 42 * The enabled versions have to be a contiguous range, which means we 43 * cannot enable and disable single versions at our whim, even though 44 * this is what the OpenSSL flags allow. The historical way this has 45 * been handled is by making a flag mean that all higher versions 46 * are disabled, if any version lower than the flag is enabled. 47 */ 48 49 min_version = 0; 50 max_version = TLS1_2_VERSION; 51 52 if ((s->internal->options & SSL_OP_NO_TLSv1) == 0) 53 min_version = TLS1_VERSION; 54 else if ((s->internal->options & SSL_OP_NO_TLSv1_1) == 0) 55 min_version = TLS1_1_VERSION; 56 else if ((s->internal->options & SSL_OP_NO_TLSv1_2) == 0) 57 min_version = TLS1_2_VERSION; 58 59 if ((s->internal->options & SSL_OP_NO_TLSv1_2) && min_version < TLS1_2_VERSION) 60 max_version = TLS1_1_VERSION; 61 if ((s->internal->options & SSL_OP_NO_TLSv1_1) && min_version < TLS1_1_VERSION) 62 max_version = TLS1_VERSION; 63 if ((s->internal->options & SSL_OP_NO_TLSv1) && min_version < TLS1_VERSION) 64 max_version = 0; 65 66 /* Everything has been disabled... */ 67 if (min_version == 0 || max_version == 0) 68 return 0; 69 70 /* Limit to configured version range. */ 71 if (!ssl_clamp_version_range(&min_version, &max_version, 72 s->internal->min_version, s->internal->max_version)) 73 return 0; 74 75 if (min_ver != NULL) 76 *min_ver = min_version; 77 if (max_ver != NULL) 78 *max_ver = max_version; 79 80 return 1; 81 } 82 83 int 84 ssl_supported_version_range(SSL *s, uint16_t *min_ver, uint16_t *max_ver) 85 { 86 uint16_t min_version, max_version; 87 88 /* DTLS cannot currently be disabled... */ 89 if (SSL_IS_DTLS(s)) { 90 min_version = max_version = DTLS1_VERSION; 91 goto done; 92 } 93 94 if (!ssl_enabled_version_range(s, &min_version, &max_version)) 95 return 0; 96 97 /* Limit to the versions supported by this method. */ 98 if (!ssl_clamp_version_range(&min_version, &max_version, 99 s->method->internal->min_version, 100 s->method->internal->max_version)) 101 return 0; 102 103 done: 104 if (min_ver != NULL) 105 *min_ver = min_version; 106 if (max_ver != NULL) 107 *max_ver = max_version; 108 109 return 1; 110 } 111 112 int 113 ssl_max_shared_version(SSL *s, uint16_t peer_ver, uint16_t *max_ver) 114 { 115 uint16_t min_version, max_version, shared_version; 116 117 *max_ver = 0; 118 119 if (SSL_IS_DTLS(s)) { 120 if (peer_ver >= DTLS1_VERSION) { 121 *max_ver = DTLS1_VERSION; 122 return 1; 123 } 124 return 0; 125 } 126 127 if (peer_ver >= TLS1_2_VERSION) 128 shared_version = TLS1_2_VERSION; 129 else if (peer_ver >= TLS1_1_VERSION) 130 shared_version = TLS1_1_VERSION; 131 else if (peer_ver >= TLS1_VERSION) 132 shared_version = TLS1_VERSION; 133 else 134 return 0; 135 136 if (!ssl_supported_version_range(s, &min_version, &max_version)) 137 return 0; 138 139 if (shared_version < min_version) 140 return 0; 141 142 if (shared_version > max_version) 143 shared_version = max_version; 144 145 *max_ver = shared_version; 146 147 return 1; 148 } 149 150 uint16_t 151 ssl_max_server_version(SSL *s) 152 { 153 uint16_t max_version, min_version = 0; 154 155 if (SSL_IS_DTLS(s)) 156 return (DTLS1_VERSION); 157 158 if (!ssl_enabled_version_range(s, &min_version, &max_version)) 159 return 0; 160 161 /* 162 * Limit to the versions supported by this method. The SSL method 163 * will be changed during version negotiation, as such we want to 164 * use the SSL method from the context. 165 */ 166 if (!ssl_clamp_version_range(&min_version, &max_version, 167 s->ctx->method->internal->min_version, 168 s->ctx->method->internal->max_version)) 169 return 0; 170 171 return (max_version); 172 } 173