Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 1 | /* |
Ben Lindstrom | 4469723 | 2001-07-04 03:32:30 +0000 | [diff] [blame] | 2 | * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 3 | * |
| 4 | * Redistribution and use in source and binary forms, with or without |
| 5 | * modification, are permitted provided that the following conditions |
| 6 | * are met: |
| 7 | * 1. Redistributions of source code must retain the above copyright |
| 8 | * notice, this list of conditions and the following disclaimer. |
| 9 | * 2. Redistributions in binary form must reproduce the above copyright |
| 10 | * notice, this list of conditions and the following disclaimer in the |
| 11 | * documentation and/or other materials provided with the distribution. |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 12 | * |
| 13 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
| 14 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| 15 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| 16 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| 17 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| 18 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 19 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 20 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 21 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| 22 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 23 | */ |
| 24 | |
| 25 | #include "includes.h" |
Damien Miller | babb47a | 2003-02-24 11:53:32 +1100 | [diff] [blame^] | 26 | RCSID("$OpenBSD: kex.c,v 1.53 2003/02/02 10:56:08 markus Exp $"); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 27 | |
| 28 | #include <openssl/crypto.h> |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 29 | |
Ben Lindstrom | 226cfa0 | 2001-01-22 05:34:40 +0000 | [diff] [blame] | 30 | #include "ssh2.h" |
| 31 | #include "xmalloc.h" |
| 32 | #include "buffer.h" |
| 33 | #include "bufaux.h" |
| 34 | #include "packet.h" |
| 35 | #include "compat.h" |
| 36 | #include "cipher.h" |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 37 | #include "kex.h" |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 38 | #include "key.h" |
Ben Lindstrom | 226cfa0 | 2001-01-22 05:34:40 +0000 | [diff] [blame] | 39 | #include "log.h" |
Ben Lindstrom | 06b33aa | 2001-02-15 03:01:59 +0000 | [diff] [blame] | 40 | #include "mac.h" |
Ben Lindstrom | b9be60a | 2001-03-11 01:49:19 +0000 | [diff] [blame] | 41 | #include "match.h" |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 42 | #include "dispatch.h" |
Ben Lindstrom | 7a2073c | 2002-03-22 02:30:41 +0000 | [diff] [blame] | 43 | #include "monitor.h" |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 44 | |
Damien Miller | b1715dc | 2000-05-30 13:44:51 +1000 | [diff] [blame] | 45 | #define KEX_COOKIE_LEN 16 |
| 46 | |
Ben Lindstrom | 7a2073c | 2002-03-22 02:30:41 +0000 | [diff] [blame] | 47 | /* Use privilege separation for sshd */ |
| 48 | int use_privsep; |
Ben Lindstrom | 7339b2a | 2002-05-15 16:25:01 +0000 | [diff] [blame] | 49 | struct monitor *pmonitor; |
Ben Lindstrom | 7a2073c | 2002-03-22 02:30:41 +0000 | [diff] [blame] | 50 | |
| 51 | |
Ben Lindstrom | bba8121 | 2001-06-25 05:01:22 +0000 | [diff] [blame] | 52 | /* prototype */ |
| 53 | static void kex_kexinit_finish(Kex *); |
| 54 | static void kex_choose_conf(Kex *); |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 55 | |
| 56 | /* put algorithm proposal into buffer */ |
Ben Lindstrom | bba8121 | 2001-06-25 05:01:22 +0000 | [diff] [blame] | 57 | static void |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 58 | kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX]) |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 59 | { |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 60 | int i; |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 61 | |
| 62 | buffer_clear(b); |
Ben Lindstrom | 5997172 | 2002-03-27 17:42:57 +0000 | [diff] [blame] | 63 | /* |
| 64 | * add a dummy cookie, the cookie will be overwritten by |
| 65 | * kex_send_kexinit(), each time a kexinit is set |
| 66 | */ |
| 67 | for (i = 0; i < KEX_COOKIE_LEN; i++) |
| 68 | buffer_put_char(b, 0); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 69 | for (i = 0; i < PROPOSAL_MAX; i++) |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 70 | buffer_put_cstring(b, proposal[i]); |
| 71 | buffer_put_char(b, 0); /* first_kex_packet_follows */ |
| 72 | buffer_put_int(b, 0); /* uint32 reserved */ |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 73 | } |
| 74 | |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 75 | /* parse buffer and return algorithm proposal */ |
Ben Lindstrom | bba8121 | 2001-06-25 05:01:22 +0000 | [diff] [blame] | 76 | static char ** |
Damien Miller | babb47a | 2003-02-24 11:53:32 +1100 | [diff] [blame^] | 77 | kex_buf2prop(Buffer *raw, int *first_kex_follows) |
Damien Miller | b1715dc | 2000-05-30 13:44:51 +1000 | [diff] [blame] | 78 | { |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 79 | Buffer b; |
Damien Miller | b1715dc | 2000-05-30 13:44:51 +1000 | [diff] [blame] | 80 | int i; |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 81 | char **proposal; |
Damien Miller | b1715dc | 2000-05-30 13:44:51 +1000 | [diff] [blame] | 82 | |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 83 | proposal = xmalloc(PROPOSAL_MAX * sizeof(char *)); |
Damien Miller | b1715dc | 2000-05-30 13:44:51 +1000 | [diff] [blame] | 84 | |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 85 | buffer_init(&b); |
| 86 | buffer_append(&b, buffer_ptr(raw), buffer_len(raw)); |
Damien Miller | b1715dc | 2000-05-30 13:44:51 +1000 | [diff] [blame] | 87 | /* skip cookie */ |
| 88 | for (i = 0; i < KEX_COOKIE_LEN; i++) |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 89 | buffer_get_char(&b); |
Damien Miller | b1715dc | 2000-05-30 13:44:51 +1000 | [diff] [blame] | 90 | /* extract kex init proposal strings */ |
| 91 | for (i = 0; i < PROPOSAL_MAX; i++) { |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 92 | proposal[i] = buffer_get_string(&b,NULL); |
| 93 | debug2("kex_parse_kexinit: %s", proposal[i]); |
Damien Miller | b1715dc | 2000-05-30 13:44:51 +1000 | [diff] [blame] | 94 | } |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 95 | /* first kex follows / reserved */ |
| 96 | i = buffer_get_char(&b); |
Damien Miller | babb47a | 2003-02-24 11:53:32 +1100 | [diff] [blame^] | 97 | if (first_kex_follows != NULL) |
| 98 | *first_kex_follows = i; |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 99 | debug2("kex_parse_kexinit: first_kex_follows %d ", i); |
| 100 | i = buffer_get_int(&b); |
| 101 | debug2("kex_parse_kexinit: reserved %d ", i); |
| 102 | buffer_free(&b); |
| 103 | return proposal; |
Damien Miller | b1715dc | 2000-05-30 13:44:51 +1000 | [diff] [blame] | 104 | } |
| 105 | |
Ben Lindstrom | bba8121 | 2001-06-25 05:01:22 +0000 | [diff] [blame] | 106 | static void |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 107 | kex_prop_free(char **proposal) |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 108 | { |
| 109 | int i; |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 110 | |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 111 | for (i = 0; i < PROPOSAL_MAX; i++) |
| 112 | xfree(proposal[i]); |
| 113 | xfree(proposal); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 114 | } |
| 115 | |
Ben Lindstrom | bba8121 | 2001-06-25 05:01:22 +0000 | [diff] [blame] | 116 | static void |
Damien Miller | 630d6f4 | 2002-01-22 23:17:30 +1100 | [diff] [blame] | 117 | kex_protocol_error(int type, u_int32_t seq, void *ctxt) |
Damien Miller | 874d77b | 2000-10-14 16:23:11 +1100 | [diff] [blame] | 118 | { |
Damien Miller | 630d6f4 | 2002-01-22 23:17:30 +1100 | [diff] [blame] | 119 | error("Hm, kex protocol error: type %d seq %u", type, seq); |
Damien Miller | 874d77b | 2000-10-14 16:23:11 +1100 | [diff] [blame] | 120 | } |
| 121 | |
Ben Lindstrom | bba8121 | 2001-06-25 05:01:22 +0000 | [diff] [blame] | 122 | static void |
Damien Miller | bc27d4e | 2002-02-13 13:54:06 +1100 | [diff] [blame] | 123 | kex_reset_dispatch(void) |
Ben Lindstrom | 8ac9106 | 2001-04-04 17:57:54 +0000 | [diff] [blame] | 124 | { |
Damien Miller | 7d05339 | 2002-01-22 23:24:13 +1100 | [diff] [blame] | 125 | dispatch_range(SSH2_MSG_TRANSPORT_MIN, |
| 126 | SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error); |
Damien Miller | bc27d4e | 2002-02-13 13:54:06 +1100 | [diff] [blame] | 127 | dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); |
Ben Lindstrom | 8ac9106 | 2001-04-04 17:57:54 +0000 | [diff] [blame] | 128 | } |
| 129 | |
| 130 | void |
Ben Lindstrom | 238abf6 | 2001-04-04 17:52:53 +0000 | [diff] [blame] | 131 | kex_finish(Kex *kex) |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 132 | { |
Damien Miller | bc27d4e | 2002-02-13 13:54:06 +1100 | [diff] [blame] | 133 | kex_reset_dispatch(); |
Ben Lindstrom | 238abf6 | 2001-04-04 17:52:53 +0000 | [diff] [blame] | 134 | |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 135 | packet_start(SSH2_MSG_NEWKEYS); |
| 136 | packet_send(); |
| 137 | /* packet_write_wait(); */ |
| 138 | debug("SSH2_MSG_NEWKEYS sent"); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 139 | |
Ben Lindstrom | 064496f | 2002-12-23 02:04:22 +0000 | [diff] [blame] | 140 | debug("expecting SSH2_MSG_NEWKEYS"); |
Damien Miller | dff5099 | 2002-01-22 23:16:32 +1100 | [diff] [blame] | 141 | packet_read_expect(SSH2_MSG_NEWKEYS); |
Ben Lindstrom | 1451908 | 2002-02-26 17:58:29 +0000 | [diff] [blame] | 142 | packet_check_eom(); |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 143 | debug("SSH2_MSG_NEWKEYS received"); |
Ben Lindstrom | 5ba23b3 | 2001-04-05 02:05:21 +0000 | [diff] [blame] | 144 | |
Ben Lindstrom | be2cc43 | 2001-04-04 23:46:07 +0000 | [diff] [blame] | 145 | kex->done = 1; |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 146 | buffer_clear(&kex->peer); |
Ben Lindstrom | 2d90e00 | 2001-04-04 02:00:54 +0000 | [diff] [blame] | 147 | /* buffer_clear(&kex->my); */ |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 148 | kex->flags &= ~KEX_INIT_SENT; |
Ben Lindstrom | 5ba23b3 | 2001-04-05 02:05:21 +0000 | [diff] [blame] | 149 | xfree(kex->name); |
| 150 | kex->name = NULL; |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 151 | } |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 152 | |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 153 | void |
| 154 | kex_send_kexinit(Kex *kex) |
| 155 | { |
Ben Lindstrom | 5997172 | 2002-03-27 17:42:57 +0000 | [diff] [blame] | 156 | u_int32_t rand = 0; |
| 157 | u_char *cookie; |
| 158 | int i; |
| 159 | |
Ben Lindstrom | 8ac9106 | 2001-04-04 17:57:54 +0000 | [diff] [blame] | 160 | if (kex == NULL) { |
| 161 | error("kex_send_kexinit: no kex, cannot rekey"); |
| 162 | return; |
| 163 | } |
Ben Lindstrom | 238abf6 | 2001-04-04 17:52:53 +0000 | [diff] [blame] | 164 | if (kex->flags & KEX_INIT_SENT) { |
| 165 | debug("KEX_INIT_SENT"); |
| 166 | return; |
| 167 | } |
Ben Lindstrom | be2cc43 | 2001-04-04 23:46:07 +0000 | [diff] [blame] | 168 | kex->done = 0; |
Ben Lindstrom | 5997172 | 2002-03-27 17:42:57 +0000 | [diff] [blame] | 169 | |
| 170 | /* generate a random cookie */ |
| 171 | if (buffer_len(&kex->my) < KEX_COOKIE_LEN) |
| 172 | fatal("kex_send_kexinit: kex proposal too short"); |
| 173 | cookie = buffer_ptr(&kex->my); |
| 174 | for (i = 0; i < KEX_COOKIE_LEN; i++) { |
| 175 | if (i % 4 == 0) |
| 176 | rand = arc4random(); |
| 177 | cookie[i] = rand; |
| 178 | rand >>= 8; |
| 179 | } |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 180 | packet_start(SSH2_MSG_KEXINIT); |
| 181 | packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my)); |
| 182 | packet_send(); |
| 183 | debug("SSH2_MSG_KEXINIT sent"); |
| 184 | kex->flags |= KEX_INIT_SENT; |
| 185 | } |
| 186 | |
| 187 | void |
Damien Miller | 630d6f4 | 2002-01-22 23:17:30 +1100 | [diff] [blame] | 188 | kex_input_kexinit(int type, u_int32_t seq, void *ctxt) |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 189 | { |
| 190 | char *ptr; |
| 191 | int dlen; |
Ben Lindstrom | 8e312f3 | 2001-04-04 23:50:21 +0000 | [diff] [blame] | 192 | int i; |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 193 | Kex *kex = (Kex *)ctxt; |
| 194 | |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 195 | debug("SSH2_MSG_KEXINIT received"); |
Ben Lindstrom | 8ac9106 | 2001-04-04 17:57:54 +0000 | [diff] [blame] | 196 | if (kex == NULL) |
| 197 | fatal("kex_input_kexinit: no kex, cannot rekey"); |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 198 | |
| 199 | ptr = packet_get_raw(&dlen); |
| 200 | buffer_append(&kex->peer, ptr, dlen); |
| 201 | |
Ben Lindstrom | 8e312f3 | 2001-04-04 23:50:21 +0000 | [diff] [blame] | 202 | /* discard packet */ |
| 203 | for (i = 0; i < KEX_COOKIE_LEN; i++) |
| 204 | packet_get_char(); |
| 205 | for (i = 0; i < PROPOSAL_MAX; i++) |
| 206 | xfree(packet_get_string(NULL)); |
Ben Lindstrom | c5a7f4f | 2002-06-25 23:19:13 +0000 | [diff] [blame] | 207 | (void) packet_get_char(); |
| 208 | (void) packet_get_int(); |
Damien Miller | 48b03fc | 2002-01-22 23:11:40 +1100 | [diff] [blame] | 209 | packet_check_eom(); |
Ben Lindstrom | 8e312f3 | 2001-04-04 23:50:21 +0000 | [diff] [blame] | 210 | |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 211 | kex_kexinit_finish(kex); |
| 212 | } |
| 213 | |
| 214 | Kex * |
Ben Lindstrom | 238abf6 | 2001-04-04 17:52:53 +0000 | [diff] [blame] | 215 | kex_setup(char *proposal[PROPOSAL_MAX]) |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 216 | { |
| 217 | Kex *kex; |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 218 | |
| 219 | kex = xmalloc(sizeof(*kex)); |
| 220 | memset(kex, 0, sizeof(*kex)); |
| 221 | buffer_init(&kex->peer); |
| 222 | buffer_init(&kex->my); |
| 223 | kex_prop2buf(&kex->my, proposal); |
Ben Lindstrom | be2cc43 | 2001-04-04 23:46:07 +0000 | [diff] [blame] | 224 | kex->done = 0; |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 225 | |
| 226 | kex_send_kexinit(kex); /* we start */ |
Damien Miller | bc27d4e | 2002-02-13 13:54:06 +1100 | [diff] [blame] | 227 | kex_reset_dispatch(); |
Ben Lindstrom | 8ac9106 | 2001-04-04 17:57:54 +0000 | [diff] [blame] | 228 | |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 229 | return kex; |
| 230 | } |
| 231 | |
Ben Lindstrom | bba8121 | 2001-06-25 05:01:22 +0000 | [diff] [blame] | 232 | static void |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 233 | kex_kexinit_finish(Kex *kex) |
| 234 | { |
| 235 | if (!(kex->flags & KEX_INIT_SENT)) |
| 236 | kex_send_kexinit(kex); |
| 237 | |
| 238 | kex_choose_conf(kex); |
| 239 | |
Ben Lindstrom | 1c37c6a | 2001-12-06 18:00:18 +0000 | [diff] [blame] | 240 | switch (kex->kex_type) { |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 241 | case DH_GRP1_SHA1: |
| 242 | kexdh(kex); |
| 243 | break; |
| 244 | case DH_GEX_SHA1: |
| 245 | kexgex(kex); |
| 246 | break; |
| 247 | default: |
| 248 | fatal("Unsupported key exchange %d", kex->kex_type); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 249 | } |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 250 | } |
| 251 | |
Ben Lindstrom | bba8121 | 2001-06-25 05:01:22 +0000 | [diff] [blame] | 252 | static void |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 253 | choose_enc(Enc *enc, char *client, char *server) |
| 254 | { |
Ben Lindstrom | b9be60a | 2001-03-11 01:49:19 +0000 | [diff] [blame] | 255 | char *name = match_list(client, server, NULL); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 256 | if (name == NULL) |
| 257 | fatal("no matching cipher found: client %s server %s", client, server); |
Damien Miller | 963f6b2 | 2002-02-19 15:21:23 +1100 | [diff] [blame] | 258 | if ((enc->cipher = cipher_by_name(name)) == NULL) |
Damien Miller | 874d77b | 2000-10-14 16:23:11 +1100 | [diff] [blame] | 259 | fatal("matching cipher is not supported: %s", name); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 260 | enc->name = name; |
| 261 | enc->enabled = 0; |
| 262 | enc->iv = NULL; |
| 263 | enc->key = NULL; |
Damien Miller | 963f6b2 | 2002-02-19 15:21:23 +1100 | [diff] [blame] | 264 | enc->key_len = cipher_keylen(enc->cipher); |
| 265 | enc->block_size = cipher_blocksize(enc->cipher); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 266 | } |
Ben Lindstrom | bba8121 | 2001-06-25 05:01:22 +0000 | [diff] [blame] | 267 | static void |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 268 | choose_mac(Mac *mac, char *client, char *server) |
| 269 | { |
Ben Lindstrom | b9be60a | 2001-03-11 01:49:19 +0000 | [diff] [blame] | 270 | char *name = match_list(client, server, NULL); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 271 | if (name == NULL) |
| 272 | fatal("no matching mac found: client %s server %s", client, server); |
Ben Lindstrom | 06b33aa | 2001-02-15 03:01:59 +0000 | [diff] [blame] | 273 | if (mac_init(mac, name) < 0) |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 274 | fatal("unsupported mac %s", name); |
Ben Lindstrom | 06b33aa | 2001-02-15 03:01:59 +0000 | [diff] [blame] | 275 | /* truncate the key */ |
| 276 | if (datafellows & SSH_BUG_HMAC) |
| 277 | mac->key_len = 16; |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 278 | mac->name = name; |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 279 | mac->key = NULL; |
| 280 | mac->enabled = 0; |
| 281 | } |
Ben Lindstrom | bba8121 | 2001-06-25 05:01:22 +0000 | [diff] [blame] | 282 | static void |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 283 | choose_comp(Comp *comp, char *client, char *server) |
| 284 | { |
Ben Lindstrom | b9be60a | 2001-03-11 01:49:19 +0000 | [diff] [blame] | 285 | char *name = match_list(client, server, NULL); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 286 | if (name == NULL) |
| 287 | fatal("no matching comp found: client %s server %s", client, server); |
| 288 | if (strcmp(name, "zlib") == 0) { |
| 289 | comp->type = 1; |
| 290 | } else if (strcmp(name, "none") == 0) { |
| 291 | comp->type = 0; |
| 292 | } else { |
| 293 | fatal("unsupported comp %s", name); |
| 294 | } |
| 295 | comp->name = name; |
| 296 | } |
Ben Lindstrom | bba8121 | 2001-06-25 05:01:22 +0000 | [diff] [blame] | 297 | static void |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 298 | choose_kex(Kex *k, char *client, char *server) |
| 299 | { |
Ben Lindstrom | b9be60a | 2001-03-11 01:49:19 +0000 | [diff] [blame] | 300 | k->name = match_list(client, server, NULL); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 301 | if (k->name == NULL) |
| 302 | fatal("no kex alg"); |
Damien Miller | 874d77b | 2000-10-14 16:23:11 +1100 | [diff] [blame] | 303 | if (strcmp(k->name, KEX_DH1) == 0) { |
| 304 | k->kex_type = DH_GRP1_SHA1; |
| 305 | } else if (strcmp(k->name, KEX_DHGEX) == 0) { |
| 306 | k->kex_type = DH_GEX_SHA1; |
| 307 | } else |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 308 | fatal("bad kex alg %s", k->name); |
| 309 | } |
Ben Lindstrom | bba8121 | 2001-06-25 05:01:22 +0000 | [diff] [blame] | 310 | static void |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 311 | choose_hostkeyalg(Kex *k, char *client, char *server) |
| 312 | { |
Ben Lindstrom | b9be60a | 2001-03-11 01:49:19 +0000 | [diff] [blame] | 313 | char *hostkeyalg = match_list(client, server, NULL); |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 314 | if (hostkeyalg == NULL) |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 315 | fatal("no hostkey alg"); |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 316 | k->hostkey_type = key_type_from_name(hostkeyalg); |
| 317 | if (k->hostkey_type == KEY_UNSPEC) |
| 318 | fatal("bad hostkey alg '%s'", hostkeyalg); |
Ben Lindstrom | 48bd7c1 | 2001-01-09 00:35:42 +0000 | [diff] [blame] | 319 | xfree(hostkeyalg); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 320 | } |
| 321 | |
Damien Miller | babb47a | 2003-02-24 11:53:32 +1100 | [diff] [blame^] | 322 | static int |
| 323 | proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX]) |
| 324 | { |
| 325 | static int check[] = { |
| 326 | PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1 |
| 327 | }; |
| 328 | int *idx; |
| 329 | char *p; |
| 330 | |
| 331 | for (idx = &check[0]; *idx != -1; idx++) { |
| 332 | if ((p = strchr(my[*idx], ',')) != NULL) |
| 333 | *p = '\0'; |
| 334 | if ((p = strchr(peer[*idx], ',')) != NULL) |
| 335 | *p = '\0'; |
| 336 | if (strcmp(my[*idx], peer[*idx]) != 0) { |
| 337 | debug2("proposal mismatch: my %s peer %s", |
| 338 | my[*idx], peer[*idx]); |
| 339 | return (0); |
| 340 | } |
| 341 | } |
| 342 | debug2("proposals match"); |
| 343 | return (1); |
| 344 | } |
| 345 | |
Ben Lindstrom | bba8121 | 2001-06-25 05:01:22 +0000 | [diff] [blame] | 346 | static void |
Ben Lindstrom | 2d90e00 | 2001-04-04 02:00:54 +0000 | [diff] [blame] | 347 | kex_choose_conf(Kex *kex) |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 348 | { |
Ben Lindstrom | 2d90e00 | 2001-04-04 02:00:54 +0000 | [diff] [blame] | 349 | Newkeys *newkeys; |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 350 | char **my, **peer; |
| 351 | char **cprop, **sprop; |
Ben Lindstrom | 2d90e00 | 2001-04-04 02:00:54 +0000 | [diff] [blame] | 352 | int nenc, nmac, ncomp; |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 353 | int mode; |
| 354 | int ctos; /* direction: if true client-to-server */ |
| 355 | int need; |
Damien Miller | babb47a | 2003-02-24 11:53:32 +1100 | [diff] [blame^] | 356 | int first_kex_follows, type; |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 357 | |
Damien Miller | babb47a | 2003-02-24 11:53:32 +1100 | [diff] [blame^] | 358 | my = kex_buf2prop(&kex->my, NULL); |
| 359 | peer = kex_buf2prop(&kex->peer, &first_kex_follows); |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 360 | |
Ben Lindstrom | 2d90e00 | 2001-04-04 02:00:54 +0000 | [diff] [blame] | 361 | if (kex->server) { |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 362 | cprop=peer; |
| 363 | sprop=my; |
| 364 | } else { |
| 365 | cprop=my; |
| 366 | sprop=peer; |
| 367 | } |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 368 | |
Ben Lindstrom | be2cc43 | 2001-04-04 23:46:07 +0000 | [diff] [blame] | 369 | /* Algorithm Negotiation */ |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 370 | for (mode = 0; mode < MODE_MAX; mode++) { |
Ben Lindstrom | 2d90e00 | 2001-04-04 02:00:54 +0000 | [diff] [blame] | 371 | newkeys = xmalloc(sizeof(*newkeys)); |
| 372 | memset(newkeys, 0, sizeof(*newkeys)); |
Ben Lindstrom | be2cc43 | 2001-04-04 23:46:07 +0000 | [diff] [blame] | 373 | kex->newkeys[mode] = newkeys; |
Ben Lindstrom | 2d90e00 | 2001-04-04 02:00:54 +0000 | [diff] [blame] | 374 | ctos = (!kex->server && mode == MODE_OUT) || (kex->server && mode == MODE_IN); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 375 | nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC; |
| 376 | nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC; |
| 377 | ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC; |
Ben Lindstrom | 2d90e00 | 2001-04-04 02:00:54 +0000 | [diff] [blame] | 378 | choose_enc (&newkeys->enc, cprop[nenc], sprop[nenc]); |
| 379 | choose_mac (&newkeys->mac, cprop[nmac], sprop[nmac]); |
| 380 | choose_comp(&newkeys->comp, cprop[ncomp], sprop[ncomp]); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 381 | debug("kex: %s %s %s %s", |
| 382 | ctos ? "client->server" : "server->client", |
Ben Lindstrom | 2d90e00 | 2001-04-04 02:00:54 +0000 | [diff] [blame] | 383 | newkeys->enc.name, |
| 384 | newkeys->mac.name, |
| 385 | newkeys->comp.name); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 386 | } |
Ben Lindstrom | 2d90e00 | 2001-04-04 02:00:54 +0000 | [diff] [blame] | 387 | choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]); |
| 388 | choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS], |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 389 | sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 390 | need = 0; |
| 391 | for (mode = 0; mode < MODE_MAX; mode++) { |
Ben Lindstrom | be2cc43 | 2001-04-04 23:46:07 +0000 | [diff] [blame] | 392 | newkeys = kex->newkeys[mode]; |
Damien Miller | 963f6b2 | 2002-02-19 15:21:23 +1100 | [diff] [blame] | 393 | if (need < newkeys->enc.key_len) |
| 394 | need = newkeys->enc.key_len; |
| 395 | if (need < newkeys->enc.block_size) |
| 396 | need = newkeys->enc.block_size; |
Ben Lindstrom | 2d90e00 | 2001-04-04 02:00:54 +0000 | [diff] [blame] | 397 | if (need < newkeys->mac.key_len) |
| 398 | need = newkeys->mac.key_len; |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 399 | } |
Damien Miller | b1715dc | 2000-05-30 13:44:51 +1000 | [diff] [blame] | 400 | /* XXX need runden? */ |
Ben Lindstrom | 2d90e00 | 2001-04-04 02:00:54 +0000 | [diff] [blame] | 401 | kex->we_need = need; |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 402 | |
Damien Miller | babb47a | 2003-02-24 11:53:32 +1100 | [diff] [blame^] | 403 | /* ignore the next message if the proposals do not match */ |
| 404 | if (first_kex_follows && !proposals_match(my, peer)) { |
| 405 | type = packet_read(); |
| 406 | debug2("skipping next packet (type %u)", type); |
| 407 | } |
| 408 | |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 409 | kex_prop_free(my); |
| 410 | kex_prop_free(peer); |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 411 | } |
| 412 | |
Ben Lindstrom | bba8121 | 2001-06-25 05:01:22 +0000 | [diff] [blame] | 413 | static u_char * |
Ben Lindstrom | 2d90e00 | 2001-04-04 02:00:54 +0000 | [diff] [blame] | 414 | derive_key(Kex *kex, int id, int need, u_char *hash, BIGNUM *shared_secret) |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 415 | { |
| 416 | Buffer b; |
Ben Lindstrom | 80cb27d | 2002-03-05 01:33:36 +0000 | [diff] [blame] | 417 | const EVP_MD *evp_md = EVP_sha1(); |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 418 | EVP_MD_CTX md; |
| 419 | char c = id; |
| 420 | int have; |
Damien Miller | 3672e4b | 2002-02-05 11:54:07 +1100 | [diff] [blame] | 421 | int mdsz = EVP_MD_size(evp_md); |
Ben Lindstrom | be2cc43 | 2001-04-04 23:46:07 +0000 | [diff] [blame] | 422 | u_char *digest = xmalloc(roundup(need, mdsz)); |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 423 | |
| 424 | buffer_init(&b); |
| 425 | buffer_put_bignum2(&b, shared_secret); |
| 426 | |
Ben Lindstrom | be2cc43 | 2001-04-04 23:46:07 +0000 | [diff] [blame] | 427 | /* K1 = HASH(K || H || "A" || session_id) */ |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 428 | EVP_DigestInit(&md, evp_md); |
Ben Lindstrom | 8c96392 | 2001-04-30 23:06:57 +0000 | [diff] [blame] | 429 | if (!(datafellows & SSH_BUG_DERIVEKEY)) |
| 430 | EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b)); |
Ben Lindstrom | be2cc43 | 2001-04-04 23:46:07 +0000 | [diff] [blame] | 431 | EVP_DigestUpdate(&md, hash, mdsz); |
| 432 | EVP_DigestUpdate(&md, &c, 1); |
Ben Lindstrom | 2d90e00 | 2001-04-04 02:00:54 +0000 | [diff] [blame] | 433 | EVP_DigestUpdate(&md, kex->session_id, kex->session_id_len); |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 434 | EVP_DigestFinal(&md, digest, NULL); |
| 435 | |
Ben Lindstrom | be2cc43 | 2001-04-04 23:46:07 +0000 | [diff] [blame] | 436 | /* |
| 437 | * expand key: |
| 438 | * Kn = HASH(K || H || K1 || K2 || ... || Kn-1) |
| 439 | * Key = K1 || K2 || ... || Kn |
| 440 | */ |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 441 | for (have = mdsz; need > have; have += mdsz) { |
| 442 | EVP_DigestInit(&md, evp_md); |
Ben Lindstrom | 8c96392 | 2001-04-30 23:06:57 +0000 | [diff] [blame] | 443 | if (!(datafellows & SSH_BUG_DERIVEKEY)) |
| 444 | EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b)); |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 445 | EVP_DigestUpdate(&md, hash, mdsz); |
| 446 | EVP_DigestUpdate(&md, digest, have); |
| 447 | EVP_DigestFinal(&md, digest + have, NULL); |
| 448 | } |
| 449 | buffer_free(&b); |
| 450 | #ifdef DEBUG_KEX |
| 451 | fprintf(stderr, "key '%c'== ", c); |
| 452 | dump_digest("key", digest, need); |
| 453 | #endif |
| 454 | return digest; |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 455 | } |
| 456 | |
Ben Lindstrom | be2cc43 | 2001-04-04 23:46:07 +0000 | [diff] [blame] | 457 | Newkeys *current_keys[MODE_MAX]; |
Ben Lindstrom | 2d90e00 | 2001-04-04 02:00:54 +0000 | [diff] [blame] | 458 | |
Ben Lindstrom | b9be60a | 2001-03-11 01:49:19 +0000 | [diff] [blame] | 459 | #define NKEYS 6 |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 460 | void |
Ben Lindstrom | 2d90e00 | 2001-04-04 02:00:54 +0000 | [diff] [blame] | 461 | kex_derive_keys(Kex *kex, u_char *hash, BIGNUM *shared_secret) |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 462 | { |
Ben Lindstrom | 46c1622 | 2000-12-22 01:43:59 +0000 | [diff] [blame] | 463 | u_char *keys[NKEYS]; |
Ben Lindstrom | 2d90e00 | 2001-04-04 02:00:54 +0000 | [diff] [blame] | 464 | int i, mode, ctos; |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 465 | |
| 466 | for (i = 0; i < NKEYS; i++) |
Ben Lindstrom | 2d90e00 | 2001-04-04 02:00:54 +0000 | [diff] [blame] | 467 | keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, shared_secret); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 468 | |
Ben Lindstrom | 064496f | 2002-12-23 02:04:22 +0000 | [diff] [blame] | 469 | debug2("kex_derive_keys"); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 470 | for (mode = 0; mode < MODE_MAX; mode++) { |
Ben Lindstrom | be2cc43 | 2001-04-04 23:46:07 +0000 | [diff] [blame] | 471 | current_keys[mode] = kex->newkeys[mode]; |
| 472 | kex->newkeys[mode] = NULL; |
Ben Lindstrom | 2d90e00 | 2001-04-04 02:00:54 +0000 | [diff] [blame] | 473 | ctos = (!kex->server && mode == MODE_OUT) || (kex->server && mode == MODE_IN); |
Ben Lindstrom | be2cc43 | 2001-04-04 23:46:07 +0000 | [diff] [blame] | 474 | current_keys[mode]->enc.iv = keys[ctos ? 0 : 1]; |
| 475 | current_keys[mode]->enc.key = keys[ctos ? 2 : 3]; |
| 476 | current_keys[mode]->mac.key = keys[ctos ? 4 : 5]; |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 477 | } |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 478 | } |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 479 | |
Ben Lindstrom | 2d90e00 | 2001-04-04 02:00:54 +0000 | [diff] [blame] | 480 | Newkeys * |
| 481 | kex_get_newkeys(int mode) |
| 482 | { |
Ben Lindstrom | be2cc43 | 2001-04-04 23:46:07 +0000 | [diff] [blame] | 483 | Newkeys *ret; |
| 484 | |
| 485 | ret = current_keys[mode]; |
| 486 | current_keys[mode] = NULL; |
| 487 | return ret; |
Ben Lindstrom | 2d90e00 | 2001-04-04 02:00:54 +0000 | [diff] [blame] | 488 | } |
| 489 | |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 490 | #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) |
| 491 | void |
| 492 | dump_digest(char *msg, u_char *digest, int len) |
| 493 | { |
| 494 | int i; |
| 495 | |
| 496 | fprintf(stderr, "%s\n", msg); |
Ben Lindstrom | 1c37c6a | 2001-12-06 18:00:18 +0000 | [diff] [blame] | 497 | for (i = 0; i< len; i++) { |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame] | 498 | fprintf(stderr, "%02x", digest[i]); |
| 499 | if (i%32 == 31) |
| 500 | fprintf(stderr, "\n"); |
| 501 | else if (i%8 == 7) |
| 502 | fprintf(stderr, " "); |
| 503 | } |
| 504 | fprintf(stderr, "\n"); |
| 505 | } |
| 506 | #endif |