| /* |
| * Copyright (c) 2000 Markus Friedl. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
| * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| #include "includes.h" |
| RCSID("$OpenBSD: sshconnect2.c,v 1.52 2001/03/10 12:48:27 markus Exp $"); |
| |
| #include <openssl/bn.h> |
| #include <openssl/md5.h> |
| #include <openssl/dh.h> |
| #include <openssl/hmac.h> |
| |
| #include "ssh.h" |
| #include "ssh2.h" |
| #include "xmalloc.h" |
| #include "rsa.h" |
| #include "buffer.h" |
| #include "packet.h" |
| #include "uidswap.h" |
| #include "compat.h" |
| #include "bufaux.h" |
| #include "cipher.h" |
| #include "kex.h" |
| #include "myproposal.h" |
| #include "key.h" |
| #include "sshconnect.h" |
| #include "authfile.h" |
| #include "cli.h" |
| #include "dispatch.h" |
| #include "authfd.h" |
| #include "log.h" |
| #include "readconf.h" |
| #include "readpass.h" |
| |
| void ssh_dh1_client(Kex *, char *, struct sockaddr *, Buffer *, Buffer *); |
| void ssh_dhgex_client(Kex *, char *, struct sockaddr *, Buffer *, Buffer *); |
| |
| /* import */ |
| extern char *client_version_string; |
| extern char *server_version_string; |
| extern Options options; |
| |
| /* |
| * SSH2 key exchange |
| */ |
| |
| u_char *session_id2 = NULL; |
| int session_id2_len = 0; |
| |
| void |
| ssh_kex2(char *host, struct sockaddr *hostaddr) |
| { |
| int i, plen; |
| Kex *kex; |
| Buffer *client_kexinit, *server_kexinit; |
| char *sprop[PROPOSAL_MAX]; |
| |
| if (options.ciphers == (char *)-1) { |
| log("No valid ciphers for protocol version 2 given, using defaults."); |
| options.ciphers = NULL; |
| } |
| if (options.ciphers != NULL) { |
| myproposal[PROPOSAL_ENC_ALGS_CTOS] = |
| myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; |
| } |
| if (options.compression) { |
| myproposal[PROPOSAL_COMP_ALGS_CTOS] = |
| myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib"; |
| } else { |
| myproposal[PROPOSAL_COMP_ALGS_CTOS] = |
| myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; |
| } |
| if (options.macs != NULL) { |
| myproposal[PROPOSAL_MAC_ALGS_CTOS] = |
| myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; |
| } |
| |
| /* buffers with raw kexinit messages */ |
| server_kexinit = xmalloc(sizeof(*server_kexinit)); |
| buffer_init(server_kexinit); |
| client_kexinit = kex_init(myproposal); |
| |
| /* algorithm negotiation */ |
| kex_exchange_kexinit(client_kexinit, server_kexinit, sprop); |
| kex = kex_choose_conf(myproposal, sprop, 0); |
| for (i = 0; i < PROPOSAL_MAX; i++) |
| xfree(sprop[i]); |
| |
| /* server authentication and session key agreement */ |
| switch(kex->kex_type) { |
| case DH_GRP1_SHA1: |
| ssh_dh1_client(kex, host, hostaddr, |
| client_kexinit, server_kexinit); |
| break; |
| case DH_GEX_SHA1: |
| ssh_dhgex_client(kex, host, hostaddr, client_kexinit, |
| server_kexinit); |
| break; |
| default: |
| fatal("Unsupported key exchange %d", kex->kex_type); |
| } |
| |
| buffer_free(client_kexinit); |
| buffer_free(server_kexinit); |
| xfree(client_kexinit); |
| xfree(server_kexinit); |
| |
| debug("Wait SSH2_MSG_NEWKEYS."); |
| packet_read_expect(&plen, SSH2_MSG_NEWKEYS); |
| packet_done(); |
| debug("GOT SSH2_MSG_NEWKEYS."); |
| |
| debug("send SSH2_MSG_NEWKEYS."); |
| packet_start(SSH2_MSG_NEWKEYS); |
| packet_send(); |
| packet_write_wait(); |
| debug("done: send SSH2_MSG_NEWKEYS."); |
| |
| #ifdef DEBUG_KEXDH |
| /* send 1st encrypted/maced/compressed message */ |
| packet_start(SSH2_MSG_IGNORE); |
| packet_put_cstring("markus"); |
| packet_send(); |
| packet_write_wait(); |
| #endif |
| debug("done: KEX2."); |
| } |
| |
| /* diffie-hellman-group1-sha1 */ |
| |
| void |
| ssh_dh1_client(Kex *kex, char *host, struct sockaddr *hostaddr, |
| Buffer *client_kexinit, Buffer *server_kexinit) |
| { |
| #ifdef DEBUG_KEXDH |
| int i; |
| #endif |
| int plen, dlen; |
| u_int klen, kout; |
| char *signature = NULL; |
| u_int slen; |
| char *server_host_key_blob = NULL; |
| Key *server_host_key; |
| u_int sbloblen; |
| DH *dh; |
| BIGNUM *dh_server_pub = 0; |
| BIGNUM *shared_secret = 0; |
| u_char *kbuf; |
| u_char *hash; |
| |
| debug("Sending SSH2_MSG_KEXDH_INIT."); |
| /* generate and send 'e', client DH public key */ |
| dh = dh_new_group1(); |
| dh_gen_key(dh, kex->we_need * 8); |
| packet_start(SSH2_MSG_KEXDH_INIT); |
| packet_put_bignum2(dh->pub_key); |
| packet_send(); |
| packet_write_wait(); |
| |
| #ifdef DEBUG_KEXDH |
| fprintf(stderr, "\np= "); |
| BN_print_fp(stderr, dh->p); |
| fprintf(stderr, "\ng= "); |
| BN_print_fp(stderr, dh->g); |
| fprintf(stderr, "\npub= "); |
| BN_print_fp(stderr, dh->pub_key); |
| fprintf(stderr, "\n"); |
| DHparams_print_fp(stderr, dh); |
| #endif |
| |
| debug("Wait SSH2_MSG_KEXDH_REPLY."); |
| |
| packet_read_expect(&plen, SSH2_MSG_KEXDH_REPLY); |
| |
| debug("Got SSH2_MSG_KEXDH_REPLY."); |
| |
| /* key, cert */ |
| server_host_key_blob = packet_get_string(&sbloblen); |
| server_host_key = key_from_blob(server_host_key_blob, sbloblen); |
| if (server_host_key == NULL) |
| fatal("cannot decode server_host_key_blob"); |
| |
| check_host_key(host, hostaddr, server_host_key, |
| options.user_hostfile2, options.system_hostfile2); |
| |
| /* DH paramter f, server public DH key */ |
| dh_server_pub = BN_new(); |
| if (dh_server_pub == NULL) |
| fatal("dh_server_pub == NULL"); |
| packet_get_bignum2(dh_server_pub, &dlen); |
| |
| #ifdef DEBUG_KEXDH |
| fprintf(stderr, "\ndh_server_pub= "); |
| BN_print_fp(stderr, dh_server_pub); |
| fprintf(stderr, "\n"); |
| debug("bits %d", BN_num_bits(dh_server_pub)); |
| #endif |
| |
| /* signed H */ |
| signature = packet_get_string(&slen); |
| packet_done(); |
| |
| if (!dh_pub_is_valid(dh, dh_server_pub)) |
| packet_disconnect("bad server public DH value"); |
| |
| klen = DH_size(dh); |
| kbuf = xmalloc(klen); |
| kout = DH_compute_key(kbuf, dh_server_pub, dh); |
| #ifdef DEBUG_KEXDH |
| debug("shared secret: len %d/%d", klen, kout); |
| fprintf(stderr, "shared secret == "); |
| for (i = 0; i< kout; i++) |
| fprintf(stderr, "%02x", (kbuf[i])&0xff); |
| fprintf(stderr, "\n"); |
| #endif |
| shared_secret = BN_new(); |
| |
| BN_bin2bn(kbuf, kout, shared_secret); |
| memset(kbuf, 0, klen); |
| xfree(kbuf); |
| |
| /* calc and verify H */ |
| hash = kex_hash( |
| client_version_string, |
| server_version_string, |
| buffer_ptr(client_kexinit), buffer_len(client_kexinit), |
| buffer_ptr(server_kexinit), buffer_len(server_kexinit), |
| server_host_key_blob, sbloblen, |
| dh->pub_key, |
| dh_server_pub, |
| shared_secret |
| ); |
| xfree(server_host_key_blob); |
| DH_free(dh); |
| BN_free(dh_server_pub); |
| #ifdef DEBUG_KEXDH |
| fprintf(stderr, "hash == "); |
| for (i = 0; i< 20; i++) |
| fprintf(stderr, "%02x", (hash[i])&0xff); |
| fprintf(stderr, "\n"); |
| #endif |
| if (key_verify(server_host_key, (u_char *)signature, slen, hash, 20) != 1) |
| fatal("key_verify failed for server_host_key"); |
| key_free(server_host_key); |
| xfree(signature); |
| |
| kex_derive_keys(kex, hash, shared_secret); |
| BN_clear_free(shared_secret); |
| packet_set_kex(kex); |
| |
| /* save session id */ |
| session_id2_len = 20; |
| session_id2 = xmalloc(session_id2_len); |
| memcpy(session_id2, hash, session_id2_len); |
| } |
| |
| /* diffie-hellman-group-exchange-sha1 */ |
| |
| /* |
| * Estimates the group order for a Diffie-Hellman group that has an |
| * attack complexity approximately the same as O(2**bits). Estimate |
| * with: O(exp(1.9223 * (ln q)^(1/3) (ln ln q)^(2/3))) |
| */ |
| |
| int |
| dh_estimate(int bits) |
| { |
| |
| if (bits < 64) |
| return (512); /* O(2**63) */ |
| if (bits < 128) |
| return (1024); /* O(2**86) */ |
| if (bits < 192) |
| return (2048); /* O(2**116) */ |
| return (4096); /* O(2**156) */ |
| } |
| |
| void |
| ssh_dhgex_client(Kex *kex, char *host, struct sockaddr *hostaddr, |
| Buffer *client_kexinit, Buffer *server_kexinit) |
| { |
| #ifdef DEBUG_KEXDH |
| int i; |
| #endif |
| int plen, dlen; |
| u_int klen, kout; |
| char *signature = NULL; |
| u_int slen, nbits; |
| char *server_host_key_blob = NULL; |
| Key *server_host_key; |
| u_int sbloblen; |
| DH *dh; |
| BIGNUM *dh_server_pub = 0; |
| BIGNUM *shared_secret = 0; |
| BIGNUM *p = 0, *g = 0; |
| u_char *kbuf; |
| u_char *hash; |
| |
| nbits = dh_estimate(kex->we_need * 8); |
| |
| debug("Sending SSH2_MSG_KEX_DH_GEX_REQUEST."); |
| packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST); |
| packet_put_int(nbits); |
| packet_send(); |
| packet_write_wait(); |
| |
| #ifdef DEBUG_KEXDH |
| fprintf(stderr, "\nnbits = %d", nbits); |
| #endif |
| |
| debug("Wait SSH2_MSG_KEX_DH_GEX_GROUP."); |
| |
| packet_read_expect(&plen, SSH2_MSG_KEX_DH_GEX_GROUP); |
| |
| debug("Got SSH2_MSG_KEX_DH_GEX_GROUP."); |
| |
| if ((p = BN_new()) == NULL) |
| fatal("BN_new"); |
| packet_get_bignum2(p, &dlen); |
| if ((g = BN_new()) == NULL) |
| fatal("BN_new"); |
| packet_get_bignum2(g, &dlen); |
| dh = dh_new_group(g, p); |
| |
| dh_gen_key(dh, kex->we_need * 8); |
| |
| #ifdef DEBUG_KEXDH |
| fprintf(stderr, "\np= "); |
| BN_print_fp(stderr, dh->p); |
| fprintf(stderr, "\ng= "); |
| BN_print_fp(stderr, dh->g); |
| fprintf(stderr, "\npub= "); |
| BN_print_fp(stderr, dh->pub_key); |
| fprintf(stderr, "\n"); |
| DHparams_print_fp(stderr, dh); |
| #endif |
| |
| debug("Sending SSH2_MSG_KEX_DH_GEX_INIT."); |
| /* generate and send 'e', client DH public key */ |
| packet_start(SSH2_MSG_KEX_DH_GEX_INIT); |
| packet_put_bignum2(dh->pub_key); |
| packet_send(); |
| packet_write_wait(); |
| |
| debug("Wait SSH2_MSG_KEX_DH_GEX_REPLY."); |
| |
| packet_read_expect(&plen, SSH2_MSG_KEX_DH_GEX_REPLY); |
| |
| debug("Got SSH2_MSG_KEXDH_REPLY."); |
| |
| /* key, cert */ |
| server_host_key_blob = packet_get_string(&sbloblen); |
| server_host_key = key_from_blob(server_host_key_blob, sbloblen); |
| if (server_host_key == NULL) |
| fatal("cannot decode server_host_key_blob"); |
| |
| check_host_key(host, hostaddr, server_host_key, |
| options.user_hostfile2, options.system_hostfile2); |
| |
| /* DH paramter f, server public DH key */ |
| dh_server_pub = BN_new(); |
| if (dh_server_pub == NULL) |
| fatal("dh_server_pub == NULL"); |
| packet_get_bignum2(dh_server_pub, &dlen); |
| |
| #ifdef DEBUG_KEXDH |
| fprintf(stderr, "\ndh_server_pub= "); |
| BN_print_fp(stderr, dh_server_pub); |
| fprintf(stderr, "\n"); |
| debug("bits %d", BN_num_bits(dh_server_pub)); |
| #endif |
| |
| /* signed H */ |
| signature = packet_get_string(&slen); |
| packet_done(); |
| |
| if (!dh_pub_is_valid(dh, dh_server_pub)) |
| packet_disconnect("bad server public DH value"); |
| |
| klen = DH_size(dh); |
| kbuf = xmalloc(klen); |
| kout = DH_compute_key(kbuf, dh_server_pub, dh); |
| #ifdef DEBUG_KEXDH |
| debug("shared secret: len %d/%d", klen, kout); |
| fprintf(stderr, "shared secret == "); |
| for (i = 0; i< kout; i++) |
| fprintf(stderr, "%02x", (kbuf[i])&0xff); |
| fprintf(stderr, "\n"); |
| #endif |
| shared_secret = BN_new(); |
| |
| BN_bin2bn(kbuf, kout, shared_secret); |
| memset(kbuf, 0, klen); |
| xfree(kbuf); |
| |
| /* calc and verify H */ |
| hash = kex_hash_gex( |
| client_version_string, |
| server_version_string, |
| buffer_ptr(client_kexinit), buffer_len(client_kexinit), |
| buffer_ptr(server_kexinit), buffer_len(server_kexinit), |
| server_host_key_blob, sbloblen, |
| nbits, dh->p, dh->g, |
| dh->pub_key, |
| dh_server_pub, |
| shared_secret |
| ); |
| xfree(server_host_key_blob); |
| DH_free(dh); |
| BN_free(dh_server_pub); |
| #ifdef DEBUG_KEXDH |
| fprintf(stderr, "hash == "); |
| for (i = 0; i< 20; i++) |
| fprintf(stderr, "%02x", (hash[i])&0xff); |
| fprintf(stderr, "\n"); |
| #endif |
| if (key_verify(server_host_key, (u_char *)signature, slen, hash, 20) != 1) |
| fatal("key_verify failed for server_host_key"); |
| key_free(server_host_key); |
| xfree(signature); |
| |
| kex_derive_keys(kex, hash, shared_secret); |
| BN_clear_free(shared_secret); |
| packet_set_kex(kex); |
| |
| /* save session id */ |
| session_id2_len = 20; |
| session_id2 = xmalloc(session_id2_len); |
| memcpy(session_id2, hash, session_id2_len); |
| } |
| |
| /* |
| * Authenticate user |
| */ |
| |
| typedef struct Authctxt Authctxt; |
| typedef struct Authmethod Authmethod; |
| |
| typedef int sign_cb_fn( |
| Authctxt *authctxt, Key *key, |
| u_char **sigp, int *lenp, u_char *data, int datalen); |
| |
| struct Authctxt { |
| const char *server_user; |
| const char *host; |
| const char *service; |
| AuthenticationConnection *agent; |
| Authmethod *method; |
| int success; |
| char *authlist; |
| Key *last_key; |
| sign_cb_fn *last_key_sign; |
| int last_key_hint; |
| }; |
| struct Authmethod { |
| char *name; /* string to compare against server's list */ |
| int (*userauth)(Authctxt *authctxt); |
| int *enabled; /* flag in option struct that enables method */ |
| int *batch_flag; /* flag in option struct that disables method */ |
| }; |
| |
| void input_userauth_success(int type, int plen, void *ctxt); |
| void input_userauth_failure(int type, int plen, void *ctxt); |
| void input_userauth_banner(int type, int plen, void *ctxt); |
| void input_userauth_error(int type, int plen, void *ctxt); |
| void input_userauth_info_req(int type, int plen, void *ctxt); |
| void input_userauth_pk_ok(int type, int plen, void *ctxt); |
| |
| int userauth_none(Authctxt *authctxt); |
| int userauth_pubkey(Authctxt *authctxt); |
| int userauth_passwd(Authctxt *authctxt); |
| int userauth_kbdint(Authctxt *authctxt); |
| |
| void userauth(Authctxt *authctxt, char *authlist); |
| |
| int |
| sign_and_send_pubkey(Authctxt *authctxt, Key *k, |
| sign_cb_fn *sign_callback); |
| void clear_auth_state(Authctxt *authctxt); |
| |
| void authmethod_clear(void); |
| Authmethod *authmethod_get(char *authlist); |
| Authmethod *authmethod_lookup(const char *name); |
| |
| Authmethod authmethods[] = { |
| {"publickey", |
| userauth_pubkey, |
| &options.pubkey_authentication, |
| NULL}, |
| {"password", |
| userauth_passwd, |
| &options.password_authentication, |
| &options.batch_mode}, |
| {"keyboard-interactive", |
| userauth_kbdint, |
| &options.kbd_interactive_authentication, |
| &options.batch_mode}, |
| {"none", |
| userauth_none, |
| NULL, |
| NULL}, |
| {NULL, NULL, NULL, NULL} |
| }; |
| |
| void |
| ssh_userauth2(const char *server_user, char *host) |
| { |
| Authctxt authctxt; |
| int type; |
| int plen; |
| |
| if (options.challenge_reponse_authentication) |
| options.kbd_interactive_authentication = 1; |
| |
| debug("send SSH2_MSG_SERVICE_REQUEST"); |
| packet_start(SSH2_MSG_SERVICE_REQUEST); |
| packet_put_cstring("ssh-userauth"); |
| packet_send(); |
| packet_write_wait(); |
| type = packet_read(&plen); |
| if (type != SSH2_MSG_SERVICE_ACCEPT) { |
| fatal("denied SSH2_MSG_SERVICE_ACCEPT: %d", type); |
| } |
| if (packet_remaining() > 0) { |
| char *reply = packet_get_string(&plen); |
| debug("service_accept: %s", reply); |
| xfree(reply); |
| } else { |
| debug("buggy server: service_accept w/o service"); |
| } |
| packet_done(); |
| debug("got SSH2_MSG_SERVICE_ACCEPT"); |
| |
| /* setup authentication context */ |
| authctxt.agent = ssh_get_authentication_connection(); |
| authctxt.server_user = server_user; |
| authctxt.host = host; |
| authctxt.service = "ssh-connection"; /* service name */ |
| authctxt.success = 0; |
| authctxt.method = authmethod_lookup("none"); |
| authctxt.authlist = NULL; |
| if (authctxt.method == NULL) |
| fatal("ssh_userauth2: internal error: cannot send userauth none request"); |
| authmethod_clear(); |
| |
| /* initial userauth request */ |
| userauth_none(&authctxt); |
| |
| dispatch_init(&input_userauth_error); |
| dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); |
| dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); |
| dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); |
| dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ |
| |
| if (authctxt.agent != NULL) |
| ssh_close_authentication_connection(authctxt.agent); |
| |
| debug("ssh-userauth2 successful: method %s", authctxt.method->name); |
| } |
| void |
| userauth(Authctxt *authctxt, char *authlist) |
| { |
| if (authlist == NULL) { |
| authlist = authctxt->authlist; |
| } else { |
| if (authctxt->authlist) |
| xfree(authctxt->authlist); |
| authctxt->authlist = authlist; |
| } |
| for (;;) { |
| Authmethod *method = authmethod_get(authlist); |
| if (method == NULL) |
| fatal("Permission denied (%s).", authlist); |
| authctxt->method = method; |
| if (method->userauth(authctxt) != 0) { |
| debug2("we sent a %s packet, wait for reply", method->name); |
| break; |
| } else { |
| debug2("we did not send a packet, disable method"); |
| method->enabled = NULL; |
| } |
| } |
| } |
| void |
| input_userauth_error(int type, int plen, void *ctxt) |
| { |
| fatal("input_userauth_error: bad message during authentication: " |
| "type %d", type); |
| } |
| void |
| input_userauth_banner(int type, int plen, void *ctxt) |
| { |
| char *msg, *lang; |
| debug3("input_userauth_banner"); |
| msg = packet_get_string(NULL); |
| lang = packet_get_string(NULL); |
| fprintf(stderr, "%s", msg); |
| xfree(msg); |
| xfree(lang); |
| } |
| void |
| input_userauth_success(int type, int plen, void *ctxt) |
| { |
| Authctxt *authctxt = ctxt; |
| if (authctxt == NULL) |
| fatal("input_userauth_success: no authentication context"); |
| if (authctxt->authlist) |
| xfree(authctxt->authlist); |
| clear_auth_state(authctxt); |
| authctxt->success = 1; /* break out */ |
| } |
| void |
| input_userauth_failure(int type, int plen, void *ctxt) |
| { |
| Authctxt *authctxt = ctxt; |
| char *authlist = NULL; |
| int partial; |
| |
| if (authctxt == NULL) |
| fatal("input_userauth_failure: no authentication context"); |
| |
| authlist = packet_get_string(NULL); |
| partial = packet_get_char(); |
| packet_done(); |
| |
| if (partial != 0) |
| log("Authenticated with partial success."); |
| debug("authentications that can continue: %s", authlist); |
| |
| clear_auth_state(authctxt); |
| userauth(authctxt, authlist); |
| } |
| void |
| input_userauth_pk_ok(int type, int plen, void *ctxt) |
| { |
| Authctxt *authctxt = ctxt; |
| Key *key = NULL; |
| Buffer b; |
| int alen, blen, pktype, sent = 0; |
| char *pkalg, *pkblob; |
| |
| if (authctxt == NULL) |
| fatal("input_userauth_pk_ok: no authentication context"); |
| if (datafellows & SSH_BUG_PKOK) { |
| /* this is similar to SSH_BUG_PKAUTH */ |
| debug2("input_userauth_pk_ok: SSH_BUG_PKOK"); |
| pkblob = packet_get_string(&blen); |
| buffer_init(&b); |
| buffer_append(&b, pkblob, blen); |
| pkalg = buffer_get_string(&b, &alen); |
| buffer_free(&b); |
| } else { |
| pkalg = packet_get_string(&alen); |
| pkblob = packet_get_string(&blen); |
| } |
| packet_done(); |
| |
| debug("input_userauth_pk_ok: pkalg %s blen %d lastkey %p hint %d", |
| pkalg, blen, authctxt->last_key, authctxt->last_key_hint); |
| |
| do { |
| if (authctxt->last_key == NULL || |
| authctxt->last_key_sign == NULL) { |
| debug("no last key or no sign cb"); |
| break; |
| } |
| debug2("last_key %s", key_fingerprint(authctxt->last_key)); |
| if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) { |
| debug("unknown pkalg %s", pkalg); |
| break; |
| } |
| if ((key = key_from_blob(pkblob, blen)) == NULL) { |
| debug("no key from blob. pkalg %s", pkalg); |
| break; |
| } |
| debug2("input_userauth_pk_ok: fp %s", key_fingerprint(key)); |
| if (!key_equal(key, authctxt->last_key)) { |
| debug("key != last_key"); |
| break; |
| } |
| sent = sign_and_send_pubkey(authctxt, key, |
| authctxt->last_key_sign); |
| } while(0); |
| |
| if (key != NULL) |
| key_free(key); |
| xfree(pkalg); |
| xfree(pkblob); |
| |
| /* unregister */ |
| clear_auth_state(authctxt); |
| dispatch_set(SSH2_MSG_USERAUTH_PK_OK, NULL); |
| |
| /* try another method if we did not send a packet*/ |
| if (sent == 0) |
| userauth(authctxt, NULL); |
| |
| } |
| |
| int |
| userauth_none(Authctxt *authctxt) |
| { |
| /* initial userauth request */ |
| packet_start(SSH2_MSG_USERAUTH_REQUEST); |
| packet_put_cstring(authctxt->server_user); |
| packet_put_cstring(authctxt->service); |
| packet_put_cstring(authctxt->method->name); |
| packet_send(); |
| return 1; |
| } |
| |
| int |
| userauth_passwd(Authctxt *authctxt) |
| { |
| static int attempt = 0; |
| char prompt[80]; |
| char *password; |
| |
| if (attempt++ >= options.number_of_password_prompts) |
| return 0; |
| |
| if(attempt != 1) |
| error("Permission denied, please try again."); |
| |
| snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", |
| authctxt->server_user, authctxt->host); |
| password = read_passphrase(prompt, 0); |
| packet_start(SSH2_MSG_USERAUTH_REQUEST); |
| packet_put_cstring(authctxt->server_user); |
| packet_put_cstring(authctxt->service); |
| packet_put_cstring(authctxt->method->name); |
| packet_put_char(0); |
| packet_put_cstring(password); |
| memset(password, 0, strlen(password)); |
| xfree(password); |
| packet_inject_ignore(64); |
| packet_send(); |
| return 1; |
| } |
| |
| void |
| clear_auth_state(Authctxt *authctxt) |
| { |
| /* XXX clear authentication state */ |
| if (authctxt->last_key != NULL && authctxt->last_key_hint == -1) { |
| debug3("clear_auth_state: key_free %p", authctxt->last_key); |
| key_free(authctxt->last_key); |
| } |
| authctxt->last_key = NULL; |
| authctxt->last_key_hint = -2; |
| authctxt->last_key_sign = NULL; |
| } |
| |
| int |
| sign_and_send_pubkey(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback) |
| { |
| Buffer b; |
| u_char *blob, *signature; |
| int bloblen, slen; |
| int skip = 0; |
| int ret = -1; |
| int have_sig = 1; |
| |
| debug3("sign_and_send_pubkey"); |
| |
| if (key_to_blob(k, &blob, &bloblen) == 0) { |
| /* we cannot handle this key */ |
| debug3("sign_and_send_pubkey: cannot handle key"); |
| return 0; |
| } |
| /* data to be signed */ |
| buffer_init(&b); |
| if (datafellows & SSH_OLD_SESSIONID) { |
| buffer_append(&b, session_id2, session_id2_len); |
| skip = session_id2_len; |
| } else { |
| buffer_put_string(&b, session_id2, session_id2_len); |
| skip = buffer_len(&b); |
| } |
| buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); |
| buffer_put_cstring(&b, authctxt->server_user); |
| buffer_put_cstring(&b, |
| datafellows & SSH_BUG_PKSERVICE ? |
| "ssh-userauth" : |
| authctxt->service); |
| if (datafellows & SSH_BUG_PKAUTH) { |
| buffer_put_char(&b, have_sig); |
| } else { |
| buffer_put_cstring(&b, authctxt->method->name); |
| buffer_put_char(&b, have_sig); |
| buffer_put_cstring(&b, key_ssh_name(k)); |
| } |
| buffer_put_string(&b, blob, bloblen); |
| |
| /* generate signature */ |
| ret = (*sign_callback)(authctxt, k, &signature, &slen, |
| buffer_ptr(&b), buffer_len(&b)); |
| if (ret == -1) { |
| xfree(blob); |
| buffer_free(&b); |
| return 0; |
| } |
| #ifdef DEBUG_PK |
| buffer_dump(&b); |
| #endif |
| if (datafellows & SSH_BUG_PKSERVICE) { |
| buffer_clear(&b); |
| buffer_append(&b, session_id2, session_id2_len); |
| skip = session_id2_len; |
| buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); |
| buffer_put_cstring(&b, authctxt->server_user); |
| buffer_put_cstring(&b, authctxt->service); |
| buffer_put_cstring(&b, authctxt->method->name); |
| buffer_put_char(&b, have_sig); |
| if (!(datafellows & SSH_BUG_PKAUTH)) |
| buffer_put_cstring(&b, key_ssh_name(k)); |
| buffer_put_string(&b, blob, bloblen); |
| } |
| xfree(blob); |
| |
| /* append signature */ |
| buffer_put_string(&b, signature, slen); |
| xfree(signature); |
| |
| /* skip session id and packet type */ |
| if (buffer_len(&b) < skip + 1) |
| fatal("userauth_pubkey: internal error"); |
| buffer_consume(&b, skip + 1); |
| |
| /* put remaining data from buffer into packet */ |
| packet_start(SSH2_MSG_USERAUTH_REQUEST); |
| packet_put_raw(buffer_ptr(&b), buffer_len(&b)); |
| buffer_free(&b); |
| packet_send(); |
| |
| return 1; |
| } |
| |
| int |
| send_pubkey_test(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback, |
| int hint) |
| { |
| u_char *blob; |
| int bloblen, have_sig = 0; |
| |
| debug3("send_pubkey_test"); |
| |
| if (key_to_blob(k, &blob, &bloblen) == 0) { |
| /* we cannot handle this key */ |
| debug3("send_pubkey_test: cannot handle key"); |
| return 0; |
| } |
| /* register callback for USERAUTH_PK_OK message */ |
| authctxt->last_key_sign = sign_callback; |
| authctxt->last_key_hint = hint; |
| authctxt->last_key = k; |
| dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); |
| |
| packet_start(SSH2_MSG_USERAUTH_REQUEST); |
| packet_put_cstring(authctxt->server_user); |
| packet_put_cstring(authctxt->service); |
| packet_put_cstring(authctxt->method->name); |
| packet_put_char(have_sig); |
| if (!(datafellows & SSH_BUG_PKAUTH)) |
| packet_put_cstring(key_ssh_name(k)); |
| packet_put_string(blob, bloblen); |
| xfree(blob); |
| packet_send(); |
| return 1; |
| } |
| |
| Key * |
| load_identity_file(char *filename) |
| { |
| Key *private; |
| char prompt[300], *passphrase; |
| int success = 0, quit, i; |
| struct stat st; |
| |
| if (stat(filename, &st) < 0) { |
| debug3("no such identity: %s", filename); |
| return NULL; |
| } |
| private = key_new(KEY_UNSPEC); |
| if (!load_private_key(filename, "", private, NULL)) { |
| if (options.batch_mode) { |
| key_free(private); |
| return NULL; |
| } |
| snprintf(prompt, sizeof prompt, |
| "Enter passphrase for key '%.100s': ", filename); |
| for (i = 0; i < options.number_of_password_prompts; i++) { |
| passphrase = read_passphrase(prompt, 0); |
| if (strcmp(passphrase, "") != 0) { |
| success = load_private_key(filename, |
| passphrase, private, NULL); |
| quit = 0; |
| } else { |
| debug2("no passphrase given, try next key"); |
| quit = 1; |
| } |
| memset(passphrase, 0, strlen(passphrase)); |
| xfree(passphrase); |
| if (success || quit) |
| break; |
| debug2("bad passphrase given, try again..."); |
| } |
| if (!success) { |
| key_free(private); |
| return NULL; |
| } |
| } |
| return private; |
| } |
| |
| int |
| identity_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, int *lenp, |
| u_char *data, int datalen) |
| { |
| Key *private; |
| int idx, ret; |
| |
| idx = authctxt->last_key_hint; |
| if (idx < 0) |
| return -1; |
| private = load_identity_file(options.identity_files[idx]); |
| if (private == NULL) |
| return -1; |
| ret = key_sign(private, sigp, lenp, data, datalen); |
| key_free(private); |
| return ret; |
| } |
| |
| int agent_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, int *lenp, |
| u_char *data, int datalen) |
| { |
| return ssh_agent_sign(authctxt->agent, key, sigp, lenp, data, datalen); |
| } |
| |
| int key_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, int *lenp, |
| u_char *data, int datalen) |
| { |
| return key_sign(key, sigp, lenp, data, datalen); |
| } |
| |
| int |
| userauth_pubkey_agent(Authctxt *authctxt) |
| { |
| static int called = 0; |
| int ret = 0; |
| char *comment; |
| Key *k; |
| |
| if (called == 0) { |
| if (ssh_get_num_identities(authctxt->agent, 2) == 0) |
| debug2("userauth_pubkey_agent: no keys at all"); |
| called = 1; |
| } |
| k = ssh_get_next_identity(authctxt->agent, &comment, 2); |
| if (k == NULL) { |
| debug2("userauth_pubkey_agent: no more keys"); |
| } else { |
| debug("userauth_pubkey_agent: testing agent key %s", comment); |
| xfree(comment); |
| ret = send_pubkey_test(authctxt, k, agent_sign_cb, -1); |
| if (ret == 0) |
| key_free(k); |
| } |
| if (ret == 0) |
| debug2("userauth_pubkey_agent: no message sent"); |
| return ret; |
| } |
| |
| int |
| userauth_pubkey(Authctxt *authctxt) |
| { |
| static int idx = 0; |
| int sent = 0; |
| Key *key; |
| char *filename; |
| |
| if (authctxt->agent != NULL) { |
| do { |
| sent = userauth_pubkey_agent(authctxt); |
| } while(!sent && authctxt->agent->howmany > 0); |
| } |
| while (!sent && idx < options.num_identity_files) { |
| key = options.identity_keys[idx]; |
| filename = options.identity_files[idx]; |
| if (key == NULL) { |
| debug("try privkey: %s", filename); |
| key = load_identity_file(filename); |
| if (key != NULL) { |
| sent = sign_and_send_pubkey(authctxt, key, |
| key_sign_cb); |
| key_free(key); |
| } |
| } else if (key->type != KEY_RSA1) { |
| debug("try pubkey: %s", filename); |
| sent = send_pubkey_test(authctxt, key, |
| identity_sign_cb, idx); |
| } |
| idx++; |
| } |
| return sent; |
| } |
| |
| /* |
| * Send userauth request message specifying keyboard-interactive method. |
| */ |
| int |
| userauth_kbdint(Authctxt *authctxt) |
| { |
| static int attempt = 0; |
| |
| if (attempt++ >= options.number_of_password_prompts) |
| return 0; |
| |
| debug2("userauth_kbdint"); |
| packet_start(SSH2_MSG_USERAUTH_REQUEST); |
| packet_put_cstring(authctxt->server_user); |
| packet_put_cstring(authctxt->service); |
| packet_put_cstring(authctxt->method->name); |
| packet_put_cstring(""); /* lang */ |
| packet_put_cstring(options.kbd_interactive_devices ? |
| options.kbd_interactive_devices : ""); |
| packet_send(); |
| |
| dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); |
| return 1; |
| } |
| |
| /* |
| * parse INFO_REQUEST, prompt user and send INFO_RESPONSE |
| */ |
| void |
| input_userauth_info_req(int type, int plen, void *ctxt) |
| { |
| Authctxt *authctxt = ctxt; |
| char *name, *inst, *lang, *prompt, *response; |
| u_int num_prompts, i; |
| int echo = 0; |
| |
| debug2("input_userauth_info_req"); |
| |
| if (authctxt == NULL) |
| fatal("input_userauth_info_req: no authentication context"); |
| |
| name = packet_get_string(NULL); |
| inst = packet_get_string(NULL); |
| lang = packet_get_string(NULL); |
| if (strlen(name) > 0) |
| cli_mesg(name); |
| if (strlen(inst) > 0) |
| cli_mesg(inst); |
| xfree(name); |
| xfree(inst); |
| xfree(lang); |
| |
| num_prompts = packet_get_int(); |
| /* |
| * Begin to build info response packet based on prompts requested. |
| * We commit to providing the correct number of responses, so if |
| * further on we run into a problem that prevents this, we have to |
| * be sure and clean this up and send a correct error response. |
| */ |
| packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); |
| packet_put_int(num_prompts); |
| |
| for (i = 0; i < num_prompts; i++) { |
| prompt = packet_get_string(NULL); |
| echo = packet_get_char(); |
| |
| response = cli_prompt(prompt, echo); |
| |
| packet_put_cstring(response); |
| memset(response, 0, strlen(response)); |
| xfree(response); |
| xfree(prompt); |
| } |
| packet_done(); /* done with parsing incoming message. */ |
| |
| packet_inject_ignore(64); |
| packet_send(); |
| } |
| |
| /* find auth method */ |
| |
| #define DELIM "," |
| |
| static char *def_authlist = "publickey,password"; |
| static char *authlist_current = NULL; /* clean copy used for comparison */ |
| static char *authname_current = NULL; /* last used auth method */ |
| static char *authlist_working = NULL; /* copy that gets modified by strtok_r() */ |
| static char *authlist_state = NULL; /* state variable for strtok_r() */ |
| |
| /* |
| * Before starting to use a new authentication method list sent by the |
| * server, reset internal variables. This should also be called when |
| * finished processing server list to free resources. |
| */ |
| void |
| authmethod_clear(void) |
| { |
| if (authlist_current != NULL) { |
| xfree(authlist_current); |
| authlist_current = NULL; |
| } |
| if (authlist_working != NULL) { |
| xfree(authlist_working); |
| authlist_working = NULL; |
| } |
| if (authname_current != NULL) { |
| xfree(authname_current); |
| authname_current = NULL; |
| } |
| if (authlist_state != NULL) |
| authlist_state = NULL; |
| return; |
| } |
| |
| /* |
| * given auth method name, if configurable options permit this method fill |
| * in auth_ident field and return true, otherwise return false. |
| */ |
| int |
| authmethod_is_enabled(Authmethod *method) |
| { |
| if (method == NULL) |
| return 0; |
| /* return false if options indicate this method is disabled */ |
| if (method->enabled == NULL || *method->enabled == 0) |
| return 0; |
| /* return false if batch mode is enabled but method needs interactive mode */ |
| if (method->batch_flag != NULL && *method->batch_flag != 0) |
| return 0; |
| return 1; |
| } |
| |
| Authmethod * |
| authmethod_lookup(const char *name) |
| { |
| Authmethod *method = NULL; |
| if (name != NULL) |
| for (method = authmethods; method->name != NULL; method++) |
| if (strcmp(name, method->name) == 0) |
| return method; |
| debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); |
| return NULL; |
| } |
| |
| /* |
| * Given the authentication method list sent by the server, return the |
| * next method we should try. If the server initially sends a nil list, |
| * use a built-in default list. If the server sends a nil list after |
| * previously sending a valid list, continue using the list originally |
| * sent. |
| */ |
| |
| Authmethod * |
| authmethod_get(char *authlist) |
| { |
| char *name = NULL, *authname_old; |
| Authmethod *method = NULL; |
| |
| /* Use a suitable default if we're passed a nil list. */ |
| if (authlist == NULL || strlen(authlist) == 0) |
| authlist = def_authlist; |
| |
| if (authlist_current == NULL || strcmp(authlist, authlist_current) != 0) { |
| /* start over if passed a different list */ |
| debug3("start over, passed a different list"); |
| authmethod_clear(); |
| authlist_current = xstrdup(authlist); |
| authlist_working = xstrdup(authlist); |
| name = strtok_r(authlist_working, DELIM, &authlist_state); |
| } else { |
| /* |
| * try to use previously used authentication method |
| * or continue to use previously passed list |
| */ |
| name = (authname_current != NULL) ? |
| authname_current : strtok_r(NULL, DELIM, &authlist_state); |
| } |
| |
| while (name != NULL) { |
| debug3("authmethod_lookup %s", name); |
| method = authmethod_lookup(name); |
| if (method != NULL && authmethod_is_enabled(method)) { |
| debug3("authmethod_is_enabled %s", name); |
| break; |
| } |
| name = strtok_r(NULL, DELIM, &authlist_state); |
| method = NULL; |
| } |
| |
| authname_old = authname_current; |
| if (method != NULL) { |
| debug("next auth method to try is %s", name); |
| authname_current = xstrdup(name); |
| } else { |
| debug("no more auth methods to try"); |
| authname_current = NULL; |
| } |
| |
| if (authname_old != NULL) |
| xfree(authname_old); |
| |
| return (method); |
| } |