1 /* $OpenBSD: kex.h,v 1.107 2019/01/23 00:30:41 djm Exp $ */ 2 3 /* 4 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 #ifndef KEX_H 27 #define KEX_H 28 29 #include "mac.h" 30 #include "crypto_api.h" 31 32 #ifdef WITH_LEAKMALLOC 33 #include "leakmalloc.h" 34 #endif 35 36 #ifdef WITH_OPENSSL 37 # ifdef OPENSSL_HAS_ECC 38 # include <openssl/ec.h> 39 # else /* OPENSSL_HAS_ECC */ 40 # define EC_KEY void 41 # define EC_GROUP void 42 # define EC_POINT void 43 # endif /* OPENSSL_HAS_ECC */ 44 #else /* WITH_OPENSSL */ 45 # define DH void 46 # define BIGNUM void 47 # define EC_KEY void 48 # define EC_GROUP void 49 # define EC_POINT void 50 #endif /* WITH_OPENSSL */ 51 52 #define KEX_COOKIE_LEN 16 53 54 #define KEX_DH1 "diffie-hellman-group1-sha1" 55 #define KEX_DH14_SHA1 "diffie-hellman-group14-sha1" 56 #define KEX_DH14_SHA256 "diffie-hellman-group14-sha256" 57 #define KEX_DH16_SHA512 "diffie-hellman-group16-sha512" 58 #define KEX_DH18_SHA512 "diffie-hellman-group18-sha512" 59 #define KEX_DHGEX_SHA1 "diffie-hellman-group-exchange-sha1" 60 #define KEX_DHGEX_SHA256 "diffie-hellman-group-exchange-sha256" 61 #define KEX_ECDH_SHA2_NISTP256 "ecdh-sha2-nistp256" 62 #define KEX_ECDH_SHA2_NISTP384 "ecdh-sha2-nistp384" 63 #define KEX_ECDH_SHA2_NISTP521 "ecdh-sha2-nistp521" 64 #define KEX_CURVE25519_SHA256 "curve25519-sha256" 65 #define KEX_CURVE25519_SHA256_OLD "curve25519-sha256@libssh.org" 66 #define KEX_SNTRUP4591761X25519_SHA512 "sntrup4591761x25519-sha512@tinyssh.org" 67 68 #define COMP_NONE 0 69 /* pre-auth compression (COMP_ZLIB) is only supported in the client */ 70 #define COMP_ZLIB 1 71 #define COMP_DELAYED 2 72 73 #define CURVE25519_SIZE 32 74 75 enum kex_init_proposals { 76 PROPOSAL_KEX_ALGS, 77 PROPOSAL_SERVER_HOST_KEY_ALGS, 78 PROPOSAL_ENC_ALGS_CTOS, 79 PROPOSAL_ENC_ALGS_STOC, 80 PROPOSAL_MAC_ALGS_CTOS, 81 PROPOSAL_MAC_ALGS_STOC, 82 PROPOSAL_COMP_ALGS_CTOS, 83 PROPOSAL_COMP_ALGS_STOC, 84 PROPOSAL_LANG_CTOS, 85 PROPOSAL_LANG_STOC, 86 PROPOSAL_MAX 87 }; 88 89 enum kex_modes { 90 MODE_IN, 91 MODE_OUT, 92 MODE_MAX 93 }; 94 95 enum kex_exchange { 96 KEX_DH_GRP1_SHA1, 97 KEX_DH_GRP14_SHA1, 98 KEX_DH_GRP14_SHA256, 99 KEX_DH_GRP16_SHA512, 100 KEX_DH_GRP18_SHA512, 101 KEX_DH_GEX_SHA1, 102 KEX_DH_GEX_SHA256, 103 KEX_ECDH_SHA2, 104 KEX_C25519_SHA256, 105 KEX_KEM_SNTRUP4591761X25519_SHA512, 106 KEX_MAX 107 }; 108 109 #define KEX_INIT_SENT 0x0001 110 #define KEX_INITIAL 0x0002 111 112 struct sshenc { 113 char *name; 114 const struct sshcipher *cipher; 115 int enabled; 116 u_int key_len; 117 u_int iv_len; 118 u_int block_size; 119 u_char *key; 120 u_char *iv; 121 }; 122 struct sshcomp { 123 u_int type; 124 int enabled; 125 char *name; 126 }; 127 struct newkeys { 128 struct sshenc enc; 129 struct sshmac mac; 130 struct sshcomp comp; 131 }; 132 133 struct ssh; 134 135 struct kex { 136 u_char *session_id; 137 size_t session_id_len; 138 struct newkeys *newkeys[MODE_MAX]; 139 u_int we_need; 140 u_int dh_need; 141 int server; 142 char *name; 143 char *hostkey_alg; 144 int hostkey_type; 145 int hostkey_nid; 146 u_int kex_type; 147 char *server_sig_algs; 148 int ext_info_c; 149 struct sshbuf *my; 150 struct sshbuf *peer; 151 struct sshbuf *client_version; 152 struct sshbuf *server_version; 153 sig_atomic_t done; 154 u_int flags; 155 int hash_alg; 156 int ec_nid; 157 char *failed_choice; 158 int (*verify_host_key)(struct sshkey *, struct ssh *); 159 struct sshkey *(*load_host_public_key)(int, int, struct ssh *); 160 struct sshkey *(*load_host_private_key)(int, int, struct ssh *); 161 int (*host_key_index)(struct sshkey *, int, struct ssh *); 162 int (*sign)(struct ssh *, struct sshkey *, struct sshkey *, 163 u_char **, size_t *, const u_char *, size_t, const char *); 164 int (*kex[KEX_MAX])(struct ssh *); 165 /* kex specific state */ 166 DH *dh; /* DH */ 167 u_int min, max, nbits; /* GEX */ 168 EC_KEY *ec_client_key; /* ECDH */ 169 const EC_GROUP *ec_group; /* ECDH */ 170 u_char c25519_client_key[CURVE25519_SIZE]; /* 25519 + KEM */ 171 u_char c25519_client_pubkey[CURVE25519_SIZE]; /* 25519 */ 172 u_char sntrup4591761_client_key[crypto_kem_sntrup4591761_SECRETKEYBYTES]; /* KEM */ 173 struct sshbuf *client_pub; 174 }; 175 176 int kex_names_valid(const char *); 177 char *kex_alg_list(char); 178 char *kex_names_cat(const char *, const char *); 179 int kex_assemble_names(char **, const char *, const char *); 180 181 int kex_exchange_identification(struct ssh *, int, const char *); 182 183 struct kex *kex_new(void); 184 int kex_ready(struct ssh *, char *[PROPOSAL_MAX]); 185 int kex_setup(struct ssh *, char *[PROPOSAL_MAX]); 186 void kex_free_newkeys(struct newkeys *); 187 void kex_free(struct kex *); 188 189 int kex_buf2prop(struct sshbuf *, int *, char ***); 190 int kex_prop2buf(struct sshbuf *, char *proposal[PROPOSAL_MAX]); 191 void kex_prop_free(char **); 192 int kex_load_hostkey(struct ssh *, struct sshkey **, struct sshkey **); 193 int kex_verify_host_key(struct ssh *, struct sshkey *); 194 195 int kex_send_kexinit(struct ssh *); 196 int kex_input_kexinit(int, u_int32_t, struct ssh *); 197 int kex_input_ext_info(int, u_int32_t, struct ssh *); 198 int kex_derive_keys(struct ssh *, u_char *, u_int, const struct sshbuf *); 199 int kex_send_newkeys(struct ssh *); 200 int kex_start_rekex(struct ssh *); 201 202 int kexgex_client(struct ssh *); 203 int kexgex_server(struct ssh *); 204 int kex_gen_client(struct ssh *); 205 int kex_gen_server(struct ssh *); 206 207 int kex_dh_keypair(struct kex *); 208 int kex_dh_enc(struct kex *, const struct sshbuf *, struct sshbuf **, 209 struct sshbuf **); 210 int kex_dh_dec(struct kex *, const struct sshbuf *, struct sshbuf **); 211 212 int kex_ecdh_keypair(struct kex *); 213 int kex_ecdh_enc(struct kex *, const struct sshbuf *, struct sshbuf **, 214 struct sshbuf **); 215 int kex_ecdh_dec(struct kex *, const struct sshbuf *, struct sshbuf **); 216 217 int kex_c25519_keypair(struct kex *); 218 int kex_c25519_enc(struct kex *, const struct sshbuf *, struct sshbuf **, 219 struct sshbuf **); 220 int kex_c25519_dec(struct kex *, const struct sshbuf *, struct sshbuf **); 221 222 int kex_kem_sntrup4591761x25519_keypair(struct kex *); 223 int kex_kem_sntrup4591761x25519_enc(struct kex *, const struct sshbuf *, 224 struct sshbuf **, struct sshbuf **); 225 int kex_kem_sntrup4591761x25519_dec(struct kex *, const struct sshbuf *, 226 struct sshbuf **); 227 228 int kex_dh_keygen(struct kex *); 229 int kex_dh_compute_key(struct kex *, BIGNUM *, struct sshbuf *); 230 231 int kexgex_hash(int, const struct sshbuf *, const struct sshbuf *, 232 const struct sshbuf *, const struct sshbuf *, const struct sshbuf *, 233 int, int, int, 234 const BIGNUM *, const BIGNUM *, const BIGNUM *, 235 const BIGNUM *, const u_char *, size_t, 236 u_char *, size_t *); 237 238 void kexc25519_keygen(u_char key[CURVE25519_SIZE], u_char pub[CURVE25519_SIZE]) 239 __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE))) 240 __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE))); 241 int kexc25519_shared_key(const u_char key[CURVE25519_SIZE], 242 const u_char pub[CURVE25519_SIZE], struct sshbuf *out) 243 __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE))) 244 __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE))); 245 int kexc25519_shared_key_ext(const u_char key[CURVE25519_SIZE], 246 const u_char pub[CURVE25519_SIZE], struct sshbuf *out, int) 247 __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE))) 248 __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE))); 249 250 #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH) 251 void dump_digest(const char *, const u_char *, int); 252 #endif 253 254 #if !defined(WITH_OPENSSL) || !defined(OPENSSL_HAS_ECC) 255 # undef EC_KEY 256 # undef EC_GROUP 257 # undef EC_POINT 258 #endif 259 260 #endif 261