1 /* $OpenBSD: kex.h,v 1.120 2023/12/18 14:45:17 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_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 #define KEX_HAS_PING 0x0020 115 116 struct sshenc { 117 char *name; 118 const struct sshcipher *cipher; 119 int enabled; 120 u_int key_len; 121 u_int iv_len; 122 u_int block_size; 123 u_char *key; 124 u_char *iv; 125 }; 126 struct sshcomp { 127 u_int type; 128 int enabled; 129 char *name; 130 }; 131 struct newkeys { 132 struct sshenc enc; 133 struct sshmac mac; 134 struct sshcomp comp; 135 }; 136 137 struct ssh; 138 struct sshbuf; 139 140 struct kex { 141 struct newkeys *newkeys[MODE_MAX]; 142 u_int we_need; 143 u_int dh_need; 144 int server; 145 char *name; 146 char *hostkey_alg; 147 int hostkey_type; 148 int hostkey_nid; 149 u_int kex_type; 150 char *server_sig_algs; 151 int ext_info_c; 152 int kex_strict; 153 struct sshbuf *my; 154 struct sshbuf *peer; 155 struct sshbuf *client_version; 156 struct sshbuf *server_version; 157 struct sshbuf *session_id; 158 struct sshbuf *initial_sig; 159 struct sshkey *initial_hostkey; 160 sig_atomic_t done; 161 u_int flags; 162 int hash_alg; 163 int ec_nid; 164 char *failed_choice; 165 int (*verify_host_key)(struct sshkey *, struct ssh *); 166 struct sshkey *(*load_host_public_key)(int, int, struct ssh *); 167 struct sshkey *(*load_host_private_key)(int, int, struct ssh *); 168 int (*host_key_index)(struct sshkey *, int, struct ssh *); 169 int (*sign)(struct ssh *, struct sshkey *, struct sshkey *, 170 u_char **, size_t *, const u_char *, size_t, const char *); 171 int (*kex[KEX_MAX])(struct ssh *); 172 /* kex specific state */ 173 DH *dh; /* DH */ 174 u_int min, max, nbits; /* GEX */ 175 EC_KEY *ec_client_key; /* ECDH */ 176 const EC_GROUP *ec_group; /* ECDH */ 177 u_char c25519_client_key[CURVE25519_SIZE]; /* 25519 + KEM */ 178 u_char c25519_client_pubkey[CURVE25519_SIZE]; /* 25519 */ 179 u_char sntrup761_client_key[crypto_kem_sntrup761_SECRETKEYBYTES]; /* KEM */ 180 struct sshbuf *client_pub; 181 }; 182 183 int kex_names_valid(const char *); 184 char *kex_alg_list(char); 185 char *kex_names_cat(const char *, const char *); 186 int kex_assemble_names(char **, const char *, const char *); 187 void kex_proposal_populate_entries(struct ssh *, char *prop[PROPOSAL_MAX], 188 const char *, const char *, const char *, const char *, const char *); 189 void kex_proposal_free_entries(char *prop[PROPOSAL_MAX]); 190 191 int kex_exchange_identification(struct ssh *, int, const char *); 192 193 struct kex *kex_new(void); 194 int kex_ready(struct ssh *, char *[PROPOSAL_MAX]); 195 int kex_setup(struct ssh *, char *[PROPOSAL_MAX]); 196 void kex_free_newkeys(struct newkeys *); 197 void kex_free(struct kex *); 198 199 int kex_buf2prop(struct sshbuf *, int *, char ***); 200 int kex_prop2buf(struct sshbuf *, char *proposal[PROPOSAL_MAX]); 201 void kex_prop_free(char **); 202 int kex_load_hostkey(struct ssh *, struct sshkey **, struct sshkey **); 203 int kex_verify_host_key(struct ssh *, struct sshkey *); 204 205 int kex_send_kexinit(struct ssh *); 206 int kex_input_kexinit(int, u_int32_t, struct ssh *); 207 int kex_input_ext_info(int, u_int32_t, struct ssh *); 208 int kex_protocol_error(int, u_int32_t, struct ssh *); 209 int kex_derive_keys(struct ssh *, u_char *, u_int, const struct sshbuf *); 210 int kex_send_newkeys(struct ssh *); 211 int kex_start_rekex(struct ssh *); 212 213 int kexgex_client(struct ssh *); 214 int kexgex_server(struct ssh *); 215 int kex_gen_client(struct ssh *); 216 int kex_gen_server(struct ssh *); 217 218 int kex_dh_keypair(struct kex *); 219 int kex_dh_enc(struct kex *, const struct sshbuf *, struct sshbuf **, 220 struct sshbuf **); 221 int kex_dh_dec(struct kex *, const struct sshbuf *, struct sshbuf **); 222 223 int kex_ecdh_keypair(struct kex *); 224 int kex_ecdh_enc(struct kex *, const struct sshbuf *, struct sshbuf **, 225 struct sshbuf **); 226 int kex_ecdh_dec(struct kex *, const struct sshbuf *, struct sshbuf **); 227 228 int kex_c25519_keypair(struct kex *); 229 int kex_c25519_enc(struct kex *, const struct sshbuf *, struct sshbuf **, 230 struct sshbuf **); 231 int kex_c25519_dec(struct kex *, const struct sshbuf *, struct sshbuf **); 232 233 int kex_kem_sntrup761x25519_keypair(struct kex *); 234 int kex_kem_sntrup761x25519_enc(struct kex *, const struct sshbuf *, 235 struct sshbuf **, struct sshbuf **); 236 int kex_kem_sntrup761x25519_dec(struct kex *, const struct sshbuf *, 237 struct sshbuf **); 238 239 int kex_dh_keygen(struct kex *); 240 int kex_dh_compute_key(struct kex *, BIGNUM *, struct sshbuf *); 241 242 int kexgex_hash(int, const struct sshbuf *, const struct sshbuf *, 243 const struct sshbuf *, const struct sshbuf *, const struct sshbuf *, 244 int, int, int, 245 const BIGNUM *, const BIGNUM *, const BIGNUM *, 246 const BIGNUM *, const u_char *, size_t, 247 u_char *, size_t *); 248 249 void kexc25519_keygen(u_char key[CURVE25519_SIZE], u_char pub[CURVE25519_SIZE]) 250 __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE))) 251 __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE))); 252 int kexc25519_shared_key(const u_char key[CURVE25519_SIZE], 253 const u_char pub[CURVE25519_SIZE], struct sshbuf *out) 254 __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE))) 255 __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE))); 256 int kexc25519_shared_key_ext(const u_char key[CURVE25519_SIZE], 257 const u_char pub[CURVE25519_SIZE], struct sshbuf *out, int) 258 __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE))) 259 __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE))); 260 261 #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH) 262 void dump_digest(const char *, const u_char *, int); 263 #endif 264 265 #if !defined(WITH_OPENSSL) || !defined(OPENSSL_HAS_ECC) 266 # undef EC_KEY 267 # undef EC_GROUP 268 # undef EC_POINT 269 #endif 270 271 #endif 272