1 /* $OpenBSD: kex.h,v 1.118 2023/03/06 12:14:48 dtucker 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_OPENSSL 33 # include <openssl/bn.h> 34 # include <openssl/dh.h> 35 # include <openssl/ecdsa.h> 36 # ifdef OPENSSL_HAS_ECC 37 # include <openssl/ec.h> 38 # else /* OPENSSL_HAS_ECC */ 39 # define EC_KEY void 40 # define EC_GROUP void 41 # define EC_POINT void 42 # endif /* OPENSSL_HAS_ECC */ 43 #else /* WITH_OPENSSL */ 44 # define DH void 45 # define BIGNUM void 46 # define EC_KEY void 47 # define EC_GROUP void 48 # define EC_POINT void 49 #endif /* WITH_OPENSSL */ 50 51 #define KEX_COOKIE_LEN 16 52 53 #define KEX_DH1 "diffie-hellman-group1-sha1" 54 #define KEX_DH14_SHA1 "diffie-hellman-group14-sha1" 55 #define KEX_DH14_SHA256 "diffie-hellman-group14-sha256" 56 #define KEX_DH16_SHA512 "diffie-hellman-group16-sha512" 57 #define KEX_DH18_SHA512 "diffie-hellman-group18-sha512" 58 #define KEX_DHGEX_SHA1 "diffie-hellman-group-exchange-sha1" 59 #define KEX_DHGEX_SHA256 "diffie-hellman-group-exchange-sha256" 60 #define KEX_ECDH_SHA2_NISTP256 "ecdh-sha2-nistp256" 61 #define KEX_ECDH_SHA2_NISTP384 "ecdh-sha2-nistp384" 62 #define KEX_ECDH_SHA2_NISTP521 "ecdh-sha2-nistp521" 63 #define KEX_CURVE25519_SHA256 "curve25519-sha256" 64 #define KEX_CURVE25519_SHA256_OLD "curve25519-sha256@libssh.org" 65 #define KEX_SNTRUP761X25519_SHA512 "sntrup761x25519-sha512@openssh.com" 66 67 #define COMP_NONE 0 68 /* pre-auth compression (COMP_ZLIB) is only supported in the client */ 69 #define COMP_ZLIB 1 70 #define COMP_DELAYED 2 71 72 #define CURVE25519_SIZE 32 73 74 enum kex_init_proposals { 75 PROPOSAL_KEX_ALGS, 76 PROPOSAL_SERVER_HOST_KEY_ALGS, 77 PROPOSAL_ENC_ALGS_CTOS, 78 PROPOSAL_ENC_ALGS_STOC, 79 PROPOSAL_MAC_ALGS_CTOS, 80 PROPOSAL_MAC_ALGS_STOC, 81 PROPOSAL_COMP_ALGS_CTOS, 82 PROPOSAL_COMP_ALGS_STOC, 83 PROPOSAL_LANG_CTOS, 84 PROPOSAL_LANG_STOC, 85 PROPOSAL_MAX 86 }; 87 88 enum kex_modes { 89 MODE_IN, 90 MODE_OUT, 91 MODE_MAX 92 }; 93 94 enum kex_exchange { 95 KEX_DH_GRP1_SHA1, 96 KEX_DH_GRP14_SHA1, 97 KEX_DH_GRP14_SHA256, 98 KEX_DH_GRP16_SHA512, 99 KEX_DH_GRP18_SHA512, 100 KEX_DH_GEX_SHA1, 101 KEX_DH_GEX_SHA256, 102 KEX_ECDH_SHA2, 103 KEX_C25519_SHA256, 104 KEX_KEM_SNTRUP761X25519_SHA512, 105 KEX_MAX 106 }; 107 108 /* kex->flags */ 109 #define KEX_INIT_SENT 0x0001 110 #define KEX_INITIAL 0x0002 111 #define KEX_HAS_PUBKEY_HOSTBOUND 0x0004 112 #define KEX_RSA_SHA2_256_SUPPORTED 0x0008 /* only set in server for now */ 113 #define KEX_RSA_SHA2_512_SUPPORTED 0x0010 /* only set in server for now */ 114 115 struct sshenc { 116 char *name; 117 const struct sshcipher *cipher; 118 int enabled; 119 u_int key_len; 120 u_int iv_len; 121 u_int block_size; 122 u_char *key; 123 u_char *iv; 124 }; 125 struct sshcomp { 126 u_int type; 127 int enabled; 128 char *name; 129 }; 130 struct newkeys { 131 struct sshenc enc; 132 struct sshmac mac; 133 struct sshcomp comp; 134 }; 135 136 struct ssh; 137 struct sshbuf; 138 139 struct kex { 140 struct newkeys *newkeys[MODE_MAX]; 141 u_int we_need; 142 u_int dh_need; 143 int server; 144 char *name; 145 char *hostkey_alg; 146 int hostkey_type; 147 int hostkey_nid; 148 u_int kex_type; 149 char *server_sig_algs; 150 int ext_info_c; 151 struct sshbuf *my; 152 struct sshbuf *peer; 153 struct sshbuf *client_version; 154 struct sshbuf *server_version; 155 struct sshbuf *session_id; 156 struct sshbuf *initial_sig; 157 struct sshkey *initial_hostkey; 158 sig_atomic_t done; 159 u_int flags; 160 int hash_alg; 161 int ec_nid; 162 char *failed_choice; 163 int (*verify_host_key)(struct sshkey *, struct ssh *); 164 struct sshkey *(*load_host_public_key)(int, int, struct ssh *); 165 struct sshkey *(*load_host_private_key)(int, int, struct ssh *); 166 int (*host_key_index)(struct sshkey *, int, struct ssh *); 167 int (*sign)(struct ssh *, struct sshkey *, struct sshkey *, 168 u_char **, size_t *, const u_char *, size_t, const char *); 169 int (*kex[KEX_MAX])(struct ssh *); 170 /* kex specific state */ 171 DH *dh; /* DH */ 172 u_int min, max, nbits; /* GEX */ 173 EC_KEY *ec_client_key; /* ECDH */ 174 const EC_GROUP *ec_group; /* ECDH */ 175 u_char c25519_client_key[CURVE25519_SIZE]; /* 25519 + KEM */ 176 u_char c25519_client_pubkey[CURVE25519_SIZE]; /* 25519 */ 177 u_char sntrup761_client_key[crypto_kem_sntrup761_SECRETKEYBYTES]; /* KEM */ 178 struct sshbuf *client_pub; 179 }; 180 181 int kex_names_valid(const char *); 182 char *kex_alg_list(char); 183 char *kex_names_cat(const char *, const char *); 184 int kex_assemble_names(char **, const char *, const char *); 185 void kex_proposal_populate_entries(struct ssh *, char *prop[PROPOSAL_MAX], 186 const char *, const char *, const char *, const char *, const char *); 187 void kex_proposal_free_entries(char *prop[PROPOSAL_MAX]); 188 189 int kex_exchange_identification(struct ssh *, int, const char *); 190 191 struct kex *kex_new(void); 192 int kex_ready(struct ssh *, char *[PROPOSAL_MAX]); 193 int kex_setup(struct ssh *, char *[PROPOSAL_MAX]); 194 void kex_free_newkeys(struct newkeys *); 195 void kex_free(struct kex *); 196 197 int kex_buf2prop(struct sshbuf *, int *, char ***); 198 int kex_prop2buf(struct sshbuf *, char *proposal[PROPOSAL_MAX]); 199 void kex_prop_free(char **); 200 int kex_load_hostkey(struct ssh *, struct sshkey **, struct sshkey **); 201 int kex_verify_host_key(struct ssh *, struct sshkey *); 202 203 int kex_send_kexinit(struct ssh *); 204 int kex_input_kexinit(int, u_int32_t, struct ssh *); 205 int kex_input_ext_info(int, u_int32_t, struct ssh *); 206 int kex_protocol_error(int, u_int32_t, struct ssh *); 207 int kex_derive_keys(struct ssh *, u_char *, u_int, const struct sshbuf *); 208 int kex_send_newkeys(struct ssh *); 209 int kex_start_rekex(struct ssh *); 210 211 int kexgex_client(struct ssh *); 212 int kexgex_server(struct ssh *); 213 int kex_gen_client(struct ssh *); 214 int kex_gen_server(struct ssh *); 215 216 int kex_dh_keypair(struct kex *); 217 int kex_dh_enc(struct kex *, const struct sshbuf *, struct sshbuf **, 218 struct sshbuf **); 219 int kex_dh_dec(struct kex *, const struct sshbuf *, struct sshbuf **); 220 221 int kex_ecdh_keypair(struct kex *); 222 int kex_ecdh_enc(struct kex *, const struct sshbuf *, struct sshbuf **, 223 struct sshbuf **); 224 int kex_ecdh_dec(struct kex *, const struct sshbuf *, struct sshbuf **); 225 226 int kex_c25519_keypair(struct kex *); 227 int kex_c25519_enc(struct kex *, const struct sshbuf *, struct sshbuf **, 228 struct sshbuf **); 229 int kex_c25519_dec(struct kex *, const struct sshbuf *, struct sshbuf **); 230 231 int kex_kem_sntrup761x25519_keypair(struct kex *); 232 int kex_kem_sntrup761x25519_enc(struct kex *, const struct sshbuf *, 233 struct sshbuf **, struct sshbuf **); 234 int kex_kem_sntrup761x25519_dec(struct kex *, const struct sshbuf *, 235 struct sshbuf **); 236 237 int kex_dh_keygen(struct kex *); 238 int kex_dh_compute_key(struct kex *, BIGNUM *, struct sshbuf *); 239 240 int kexgex_hash(int, const struct sshbuf *, const struct sshbuf *, 241 const struct sshbuf *, const struct sshbuf *, const struct sshbuf *, 242 int, int, int, 243 const BIGNUM *, const BIGNUM *, const BIGNUM *, 244 const BIGNUM *, const u_char *, size_t, 245 u_char *, size_t *); 246 247 void kexc25519_keygen(u_char key[CURVE25519_SIZE], u_char pub[CURVE25519_SIZE]) 248 __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE))) 249 __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE))); 250 int kexc25519_shared_key(const u_char key[CURVE25519_SIZE], 251 const u_char pub[CURVE25519_SIZE], struct sshbuf *out) 252 __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE))) 253 __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE))); 254 int kexc25519_shared_key_ext(const u_char key[CURVE25519_SIZE], 255 const u_char pub[CURVE25519_SIZE], struct sshbuf *out, int) 256 __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE))) 257 __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE))); 258 259 #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH) 260 void dump_digest(const char *, const u_char *, int); 261 #endif 262 263 #if !defined(WITH_OPENSSL) || !defined(OPENSSL_HAS_ECC) 264 # undef EC_KEY 265 # undef EC_GROUP 266 # undef EC_POINT 267 #endif 268 269 #endif 270