1 /* $OpenBSD: kex.h,v 1.123 2024/05/17 00:30:23 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/ec.h> 36 #include <openssl/ecdsa.h> 37 #else /* OPENSSL */ 38 #define BIGNUM void 39 #define DH void 40 #define EC_KEY void 41 #define EC_GROUP void 42 #endif /* WITH_OPENSSL */ 43 44 #define KEX_COOKIE_LEN 16 45 46 #define KEX_DH1 "diffie-hellman-group1-sha1" 47 #define KEX_DH14_SHA1 "diffie-hellman-group14-sha1" 48 #define KEX_DH14_SHA256 "diffie-hellman-group14-sha256" 49 #define KEX_DH16_SHA512 "diffie-hellman-group16-sha512" 50 #define KEX_DH18_SHA512 "diffie-hellman-group18-sha512" 51 #define KEX_DHGEX_SHA1 "diffie-hellman-group-exchange-sha1" 52 #define KEX_DHGEX_SHA256 "diffie-hellman-group-exchange-sha256" 53 #define KEX_ECDH_SHA2_NISTP256 "ecdh-sha2-nistp256" 54 #define KEX_ECDH_SHA2_NISTP384 "ecdh-sha2-nistp384" 55 #define KEX_ECDH_SHA2_NISTP521 "ecdh-sha2-nistp521" 56 #define KEX_CURVE25519_SHA256 "curve25519-sha256" 57 #define KEX_CURVE25519_SHA256_OLD "curve25519-sha256@libssh.org" 58 #define KEX_SNTRUP761X25519_SHA512 "sntrup761x25519-sha512@openssh.com" 59 60 #define COMP_NONE 0 61 /* pre-auth compression (COMP_ZLIB) is only supported in the client */ 62 #define COMP_ZLIB 1 63 #define COMP_DELAYED 2 64 65 #define CURVE25519_SIZE 32 66 67 enum kex_init_proposals { 68 PROPOSAL_KEX_ALGS, 69 PROPOSAL_SERVER_HOST_KEY_ALGS, 70 PROPOSAL_ENC_ALGS_CTOS, 71 PROPOSAL_ENC_ALGS_STOC, 72 PROPOSAL_MAC_ALGS_CTOS, 73 PROPOSAL_MAC_ALGS_STOC, 74 PROPOSAL_COMP_ALGS_CTOS, 75 PROPOSAL_COMP_ALGS_STOC, 76 PROPOSAL_LANG_CTOS, 77 PROPOSAL_LANG_STOC, 78 PROPOSAL_MAX 79 }; 80 81 enum kex_modes { 82 MODE_IN, 83 MODE_OUT, 84 MODE_MAX 85 }; 86 87 enum kex_exchange { 88 KEX_DH_GRP1_SHA1 = 1, 89 KEX_DH_GRP14_SHA1, 90 KEX_DH_GRP14_SHA256, 91 KEX_DH_GRP16_SHA512, 92 KEX_DH_GRP18_SHA512, 93 KEX_DH_GEX_SHA1, 94 KEX_DH_GEX_SHA256, 95 KEX_ECDH_SHA2, 96 KEX_C25519_SHA256, 97 KEX_KEM_SNTRUP761X25519_SHA512, 98 KEX_MAX 99 }; 100 101 /* kex->flags */ 102 #define KEX_INIT_SENT 0x0001 103 #define KEX_INITIAL 0x0002 104 #define KEX_HAS_PUBKEY_HOSTBOUND 0x0004 105 #define KEX_RSA_SHA2_256_SUPPORTED 0x0008 /* only set in server for now */ 106 #define KEX_RSA_SHA2_512_SUPPORTED 0x0010 /* only set in server for now */ 107 #define KEX_HAS_PING 0x0020 108 #define KEX_HAS_EXT_INFO_IN_AUTH 0x0040 109 110 struct sshenc { 111 char *name; 112 const struct sshcipher *cipher; 113 int enabled; 114 u_int key_len; 115 u_int iv_len; 116 u_int block_size; 117 u_char *key; 118 u_char *iv; 119 }; 120 struct sshcomp { 121 u_int type; 122 int enabled; 123 char *name; 124 }; 125 struct newkeys { 126 struct sshenc enc; 127 struct sshmac mac; 128 struct sshcomp comp; 129 }; 130 131 struct ssh; 132 struct sshbuf; 133 134 struct kex { 135 struct newkeys *newkeys[MODE_MAX]; 136 u_int we_need; 137 u_int dh_need; 138 int server; 139 char *name; 140 char *hostkey_alg; 141 int hostkey_type; 142 int hostkey_nid; 143 u_int kex_type; 144 char *server_sig_algs; 145 int ext_info_c; 146 int ext_info_s; 147 int kex_strict; 148 int ext_info_received; 149 struct sshbuf *my; 150 struct sshbuf *peer; 151 struct sshbuf *client_version; 152 struct sshbuf *server_version; 153 struct sshbuf *session_id; 154 struct sshbuf *initial_sig; 155 struct sshkey *initial_hostkey; 156 sig_atomic_t done; 157 u_int flags; 158 int hash_alg; 159 int ec_nid; 160 char *failed_choice; 161 int (*verify_host_key)(struct sshkey *, struct ssh *); 162 struct sshkey *(*load_host_public_key)(int, int, struct ssh *); 163 struct sshkey *(*load_host_private_key)(int, int, struct ssh *); 164 int (*host_key_index)(struct sshkey *, int, struct ssh *); 165 int (*sign)(struct ssh *, struct sshkey *, struct sshkey *, 166 u_char **, size_t *, const u_char *, size_t, const char *); 167 int (*kex[KEX_MAX])(struct ssh *); 168 /* kex specific state */ 169 DH *dh; /* DH */ 170 u_int min, max, nbits; /* GEX */ 171 EC_KEY *ec_client_key; /* ECDH */ 172 const EC_GROUP *ec_group; /* ECDH */ 173 u_char c25519_client_key[CURVE25519_SIZE]; /* 25519 + KEM */ 174 u_char c25519_client_pubkey[CURVE25519_SIZE]; /* 25519 */ 175 u_char sntrup761_client_key[crypto_kem_sntrup761_SECRETKEYBYTES]; /* KEM */ 176 struct sshbuf *client_pub; 177 }; 178 179 int kex_name_valid(const char *); 180 u_int kex_type_from_name(const char *); 181 int kex_hash_from_name(const char *); 182 int kex_nid_from_name(const char *); 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_has_any_alg(const char *, const char *); 187 int kex_assemble_names(char **, const char *, const char *); 188 void kex_proposal_populate_entries(struct ssh *, char *prop[PROPOSAL_MAX], 189 const char *, const char *, const char *, const char *, const char *); 190 void kex_proposal_free_entries(char *prop[PROPOSAL_MAX]); 191 192 int kex_exchange_identification(struct ssh *, int, const char *); 193 194 struct kex *kex_new(void); 195 int kex_ready(struct ssh *, char *[PROPOSAL_MAX]); 196 int kex_setup(struct ssh *, char *[PROPOSAL_MAX]); 197 void kex_free_newkeys(struct newkeys *); 198 void kex_free(struct kex *); 199 200 int kex_buf2prop(struct sshbuf *, int *, char ***); 201 int kex_prop2buf(struct sshbuf *, char *proposal[PROPOSAL_MAX]); 202 void kex_prop_free(char **); 203 int kex_load_hostkey(struct ssh *, struct sshkey **, struct sshkey **); 204 int kex_verify_host_key(struct ssh *, struct sshkey *); 205 206 int kex_send_kexinit(struct ssh *); 207 int kex_input_kexinit(int, u_int32_t, struct ssh *); 208 int kex_input_ext_info(int, u_int32_t, struct ssh *); 209 int kex_protocol_error(int, u_int32_t, struct ssh *); 210 int kex_derive_keys(struct ssh *, u_char *, u_int, const struct sshbuf *); 211 int kex_send_newkeys(struct ssh *); 212 int kex_start_rekex(struct ssh *); 213 int kex_server_update_ext_info(struct ssh *); 214 void kex_set_server_sig_algs(struct ssh *, const char *); 215 216 int kexgex_client(struct ssh *); 217 int kexgex_server(struct ssh *); 218 int kex_gen_client(struct ssh *); 219 int kex_gen_server(struct ssh *); 220 221 int kex_dh_keypair(struct kex *); 222 int kex_dh_enc(struct kex *, const struct sshbuf *, struct sshbuf **, 223 struct sshbuf **); 224 int kex_dh_dec(struct kex *, const struct sshbuf *, struct sshbuf **); 225 226 int kex_ecdh_keypair(struct kex *); 227 int kex_ecdh_enc(struct kex *, const struct sshbuf *, struct sshbuf **, 228 struct sshbuf **); 229 int kex_ecdh_dec(struct kex *, const struct sshbuf *, struct sshbuf **); 230 231 int kex_c25519_keypair(struct kex *); 232 int kex_c25519_enc(struct kex *, const struct sshbuf *, struct sshbuf **, 233 struct sshbuf **); 234 int kex_c25519_dec(struct kex *, const struct sshbuf *, struct sshbuf **); 235 236 int kex_kem_sntrup761x25519_keypair(struct kex *); 237 int kex_kem_sntrup761x25519_enc(struct kex *, const struct sshbuf *, 238 struct sshbuf **, struct sshbuf **); 239 int kex_kem_sntrup761x25519_dec(struct kex *, const struct sshbuf *, 240 struct sshbuf **); 241 242 int kex_dh_keygen(struct kex *); 243 int kex_dh_compute_key(struct kex *, BIGNUM *, struct sshbuf *); 244 245 int kexgex_hash(int, const struct sshbuf *, const struct sshbuf *, 246 const struct sshbuf *, const struct sshbuf *, const struct sshbuf *, 247 int, int, int, 248 const BIGNUM *, const BIGNUM *, const BIGNUM *, 249 const BIGNUM *, const u_char *, size_t, 250 u_char *, size_t *); 251 252 void kexc25519_keygen(u_char key[CURVE25519_SIZE], u_char pub[CURVE25519_SIZE]) 253 __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE))) 254 __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE))); 255 int kexc25519_shared_key(const u_char key[CURVE25519_SIZE], 256 const u_char pub[CURVE25519_SIZE], struct sshbuf *out) 257 __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE))) 258 __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE))); 259 int kexc25519_shared_key_ext(const u_char key[CURVE25519_SIZE], 260 const u_char pub[CURVE25519_SIZE], struct sshbuf *out, int) 261 __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE))) 262 __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE))); 263 264 #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH) 265 void dump_digest(const char *, const u_char *, int); 266 #endif 267 268 #endif 269