diff options
Diffstat (limited to 'crypto/openssh/sshconnect2.c')
| -rw-r--r-- | crypto/openssh/sshconnect2.c | 1497 |
1 files changed, 1497 insertions, 0 deletions
diff --git a/crypto/openssh/sshconnect2.c b/crypto/openssh/sshconnect2.c new file mode 100644 index 0000000..dd971a9 --- /dev/null +++ b/crypto/openssh/sshconnect2.c @@ -0,0 +1,1497 @@ +/* $OpenBSD: sshconnect2.c,v 1.162 2006/08/30 00:06:51 dtucker Exp $ */ +/* + * 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" + +#include <sys/types.h> +#include <sys/socket.h> +#include <sys/wait.h> +#include <sys/stat.h> + +#include <errno.h> +#include <pwd.h> +#include <signal.h> +#include <stdarg.h> +#include <stdio.h> +#include <string.h> +#include <unistd.h> + +#include "openbsd-compat/sys-queue.h" + +#include "xmalloc.h" +#include "ssh.h" +#include "ssh2.h" +#include "buffer.h" +#include "packet.h" +#include "compat.h" +#include "cipher.h" +#include "key.h" +#include "kex.h" +#include "myproposal.h" +#include "sshconnect.h" +#include "authfile.h" +#include "dh.h" +#include "authfd.h" +#include "log.h" +#include "readconf.h" +#include "misc.h" +#include "match.h" +#include "dispatch.h" +#include "canohost.h" +#include "msg.h" +#include "pathnames.h" +#include "uidswap.h" + +#ifdef GSSAPI +#include "ssh-gss.h" +#endif + +/* import */ +extern char *client_version_string; +extern char *server_version_string; +extern Options options; + +/* + * SSH2 key exchange + */ + +u_char *session_id2 = NULL; +u_int session_id2_len = 0; + +char *xxx_host; +struct sockaddr *xxx_hostaddr; + +Kex *xxx_kex = NULL; + +static int +verify_host_key_callback(Key *hostkey) +{ + if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1) + fatal("Host key verification failed."); + return 0; +} + +void +ssh_kex2(char *host, struct sockaddr *hostaddr) +{ + Kex *kex; + + xxx_host = host; + xxx_hostaddr = hostaddr; + + if (options.ciphers == (char *)-1) { + logit("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; + } + myproposal[PROPOSAL_ENC_ALGS_CTOS] = + compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); + myproposal[PROPOSAL_ENC_ALGS_STOC] = + compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); + if (options.compression) { + myproposal[PROPOSAL_COMP_ALGS_CTOS] = + myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none"; + } else { + myproposal[PROPOSAL_COMP_ALGS_CTOS] = + myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib"; + } + if (options.macs != NULL) { + myproposal[PROPOSAL_MAC_ALGS_CTOS] = + myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; + } + if (options.hostkeyalgorithms != NULL) + myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = + options.hostkeyalgorithms; + + if (options.rekey_limit) + packet_set_rekey_limit(options.rekey_limit); + + /* start key exchange */ + kex = kex_setup(myproposal); + kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client; + kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client; + kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; + kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; + kex->client_version_string=client_version_string; + kex->server_version_string=server_version_string; + kex->verify_host_key=&verify_host_key_callback; + + xxx_kex = kex; + + dispatch_run(DISPATCH_BLOCK, &kex->done, kex); + + session_id2 = kex->session_id; + session_id2_len = kex->session_id_len; + +#ifdef DEBUG_KEXDH + /* send 1st encrypted/maced/compressed message */ + packet_start(SSH2_MSG_IGNORE); + packet_put_cstring("markus"); + packet_send(); + packet_write_wait(); +#endif +} + +/* + * Authenticate user + */ + +typedef struct Authctxt Authctxt; +typedef struct Authmethod Authmethod; +typedef struct identity Identity; +typedef struct idlist Idlist; + +struct identity { + TAILQ_ENTRY(identity) next; + AuthenticationConnection *ac; /* set if agent supports key */ + Key *key; /* public/private key */ + char *filename; /* comment for agent-only keys */ + int tried; + int isprivate; /* key points to the private key */ +}; +TAILQ_HEAD(idlist, identity); + +struct Authctxt { + const char *server_user; + const char *local_user; + const char *host; + const char *service; + Authmethod *method; + int success; + char *authlist; + /* pubkey */ + Idlist keys; + AuthenticationConnection *agent; + /* hostbased */ + Sensitive *sensitive; + /* kbd-interactive */ + int info_req_seen; + /* generic */ + void *methoddata; +}; +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, u_int32_t, void *); +void input_userauth_failure(int, u_int32_t, void *); +void input_userauth_banner(int, u_int32_t, void *); +void input_userauth_error(int, u_int32_t, void *); +void input_userauth_info_req(int, u_int32_t, void *); +void input_userauth_pk_ok(int, u_int32_t, void *); +void input_userauth_passwd_changereq(int, u_int32_t, void *); + +int userauth_none(Authctxt *); +int userauth_pubkey(Authctxt *); +int userauth_passwd(Authctxt *); +int userauth_kbdint(Authctxt *); +int userauth_hostbased(Authctxt *); +int userauth_kerberos(Authctxt *); + +#ifdef GSSAPI +int userauth_gssapi(Authctxt *authctxt); +void input_gssapi_response(int type, u_int32_t, void *); +void input_gssapi_token(int type, u_int32_t, void *); +void input_gssapi_hash(int type, u_int32_t, void *); +void input_gssapi_error(int, u_int32_t, void *); +void input_gssapi_errtok(int, u_int32_t, void *); +#endif + +void userauth(Authctxt *, char *); + +static int sign_and_send_pubkey(Authctxt *, Identity *); +static void pubkey_prepare(Authctxt *); +static void pubkey_cleanup(Authctxt *); +static Key *load_identity_file(char *); + +static Authmethod *authmethod_get(char *authlist); +static Authmethod *authmethod_lookup(const char *name); +static char *authmethods_get(void); + +Authmethod authmethods[] = { +#ifdef GSSAPI + {"gssapi-with-mic", + userauth_gssapi, + &options.gss_authentication, + NULL}, +#endif + {"hostbased", + userauth_hostbased, + &options.hostbased_authentication, + NULL}, + {"publickey", + userauth_pubkey, + &options.pubkey_authentication, + NULL}, + {"keyboard-interactive", + userauth_kbdint, + &options.kbd_interactive_authentication, + &options.batch_mode}, + {"password", + userauth_passwd, + &options.password_authentication, + &options.batch_mode}, + {"none", + userauth_none, + NULL, + NULL}, + {NULL, NULL, NULL, NULL} +}; + +void +ssh_userauth2(const char *local_user, const char *server_user, char *host, + Sensitive *sensitive) +{ + Authctxt authctxt; + int type; + + if (options.challenge_response_authentication) + options.kbd_interactive_authentication = 1; + + packet_start(SSH2_MSG_SERVICE_REQUEST); + packet_put_cstring("ssh-userauth"); + packet_send(); + debug("SSH2_MSG_SERVICE_REQUEST sent"); + packet_write_wait(); + type = packet_read(); + if (type != SSH2_MSG_SERVICE_ACCEPT) + fatal("Server denied authentication request: %d", type); + if (packet_remaining() > 0) { + char *reply = packet_get_string(NULL); + debug2("service_accept: %s", reply); + xfree(reply); + } else { + debug2("buggy server: service_accept w/o service"); + } + packet_check_eom(); + debug("SSH2_MSG_SERVICE_ACCEPT received"); + + if (options.preferred_authentications == NULL) + options.preferred_authentications = authmethods_get(); + + /* setup authentication context */ + memset(&authctxt, 0, sizeof(authctxt)); + pubkey_prepare(&authctxt); + authctxt.server_user = server_user; + authctxt.local_user = local_user; + authctxt.host = host; + authctxt.service = "ssh-connection"; /* service name */ + authctxt.success = 0; + authctxt.method = authmethod_lookup("none"); + authctxt.authlist = NULL; + authctxt.methoddata = NULL; + authctxt.sensitive = sensitive; + authctxt.info_req_seen = 0; + if (authctxt.method == NULL) + fatal("ssh_userauth2: internal error: cannot send userauth none request"); + + /* 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 */ + + pubkey_cleanup(&authctxt); + dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL); + + debug("Authentication succeeded (%s).", authctxt.method->name); +} + +void +userauth(Authctxt *authctxt, char *authlist) +{ + if (authctxt->methoddata) { + xfree(authctxt->methoddata); + authctxt->methoddata = NULL; + } + 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; + + /* reset the per method handler */ + dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN, + SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL); + + /* and try new 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, u_int32_t seq, void *ctxt) +{ + fatal("input_userauth_error: bad message during authentication: " + "type %d", type); +} + +void +input_userauth_banner(int type, u_int32_t seq, void *ctxt) +{ + char *msg, *lang; + + debug3("input_userauth_banner"); + msg = packet_get_string(NULL); + lang = packet_get_string(NULL); + if (options.log_level >= SYSLOG_LEVEL_INFO) + fprintf(stderr, "%s", msg); + xfree(msg); + xfree(lang); +} + +void +input_userauth_success(int type, u_int32_t seq, void *ctxt) +{ + Authctxt *authctxt = ctxt; + if (authctxt == NULL) + fatal("input_userauth_success: no authentication context"); + if (authctxt->authlist) { + xfree(authctxt->authlist); + authctxt->authlist = NULL; + } + if (authctxt->methoddata) { + xfree(authctxt->methoddata); + authctxt->methoddata = NULL; + } + authctxt->success = 1; /* break out */ +} + +void +input_userauth_failure(int type, u_int32_t seq, 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_check_eom(); + + if (partial != 0) + logit("Authenticated with partial success."); + debug("Authentications that can continue: %s", authlist); + + userauth(authctxt, authlist); +} +void +input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt) +{ + Authctxt *authctxt = ctxt; + Key *key = NULL; + Identity *id = NULL; + Buffer b; + int pktype, sent = 0; + u_int alen, blen; + char *pkalg, *fp; + u_char *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_check_eom(); + + debug("Server accepts key: pkalg %s blen %u", pkalg, blen); + + if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) { + debug("unknown pkalg %s", pkalg); + goto done; + } + if ((key = key_from_blob(pkblob, blen)) == NULL) { + debug("no key from blob. pkalg %s", pkalg); + goto done; + } + if (key->type != pktype) { + error("input_userauth_pk_ok: type mismatch " + "for decoded key (received %d, expected %d)", + key->type, pktype); + goto done; + } + fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX); + debug2("input_userauth_pk_ok: fp %s", fp); + xfree(fp); + + /* + * search keys in the reverse order, because last candidate has been + * moved to the end of the queue. this also avoids confusion by + * duplicate keys + */ + TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) { + if (key_equal(key, id->key)) { + sent = sign_and_send_pubkey(authctxt, id); + break; + } + } +done: + if (key != NULL) + key_free(key); + xfree(pkalg); + xfree(pkblob); + + /* try another method if we did not send a packet */ + if (sent == 0) + userauth(authctxt, NULL); +} + +#ifdef GSSAPI +int +userauth_gssapi(Authctxt *authctxt) +{ + Gssctxt *gssctxt = NULL; + static gss_OID_set gss_supported = NULL; + static u_int mech = 0; + OM_uint32 min; + int ok = 0; + + /* Try one GSSAPI method at a time, rather than sending them all at + * once. */ + + if (gss_supported == NULL) + gss_indicate_mechs(&min, &gss_supported); + + /* Check to see if the mechanism is usable before we offer it */ + while (mech < gss_supported->count && !ok) { + /* My DER encoding requires length<128 */ + if (gss_supported->elements[mech].length < 128 && + ssh_gssapi_check_mechanism(&gssctxt, + &gss_supported->elements[mech], authctxt->host)) { + ok = 1; /* Mechanism works */ + } else { + mech++; + } + } + + if (!ok) + return 0; + + authctxt->methoddata=(void *)gssctxt; + + 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_int(1); + + packet_put_int((gss_supported->elements[mech].length) + 2); + packet_put_char(SSH_GSS_OIDTYPE); + packet_put_char(gss_supported->elements[mech].length); + packet_put_raw(gss_supported->elements[mech].elements, + gss_supported->elements[mech].length); + + packet_send(); + + dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response); + dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); + dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error); + dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); + + mech++; /* Move along to next candidate */ + + return 1; +} + +static OM_uint32 +process_gssapi_token(void *ctxt, gss_buffer_t recv_tok) +{ + Authctxt *authctxt = ctxt; + Gssctxt *gssctxt = authctxt->methoddata; + gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; + gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; + gss_buffer_desc gssbuf; + OM_uint32 status, ms, flags; + Buffer b; + + status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, + recv_tok, &send_tok, &flags); + + if (send_tok.length > 0) { + if (GSS_ERROR(status)) + packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); + else + packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); + + packet_put_string(send_tok.value, send_tok.length); + packet_send(); + gss_release_buffer(&ms, &send_tok); + } + + if (status == GSS_S_COMPLETE) { + /* send either complete or MIC, depending on mechanism */ + if (!(flags & GSS_C_INTEG_FLAG)) { + packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE); + packet_send(); + } else { + ssh_gssapi_buildmic(&b, authctxt->server_user, + authctxt->service, "gssapi-with-mic"); + + gssbuf.value = buffer_ptr(&b); + gssbuf.length = buffer_len(&b); + + status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic); + + if (!GSS_ERROR(status)) { + packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC); + packet_put_string(mic.value, mic.length); + + packet_send(); + } + + buffer_free(&b); + gss_release_buffer(&ms, &mic); + } + } + + return status; +} + +void +input_gssapi_response(int type, u_int32_t plen, void *ctxt) +{ + Authctxt *authctxt = ctxt; + Gssctxt *gssctxt; + int oidlen; + char *oidv; + + if (authctxt == NULL) + fatal("input_gssapi_response: no authentication context"); + gssctxt = authctxt->methoddata; + + /* Setup our OID */ + oidv = packet_get_string(&oidlen); + + if (oidlen <= 2 || + oidv[0] != SSH_GSS_OIDTYPE || + oidv[1] != oidlen - 2) { + xfree(oidv); + debug("Badly encoded mechanism OID received"); + userauth(authctxt, NULL); + return; + } + + if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2)) + fatal("Server returned different OID than expected"); + + packet_check_eom(); + + xfree(oidv); + + if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) { + /* Start again with next method on list */ + debug("Trying to start again"); + userauth(authctxt, NULL); + return; + } +} + +void +input_gssapi_token(int type, u_int32_t plen, void *ctxt) +{ + Authctxt *authctxt = ctxt; + gss_buffer_desc recv_tok; + OM_uint32 status; + u_int slen; + + if (authctxt == NULL) + fatal("input_gssapi_response: no authentication context"); + + recv_tok.value = packet_get_string(&slen); + recv_tok.length = slen; /* safe typecast */ + + packet_check_eom(); + + status = process_gssapi_token(ctxt, &recv_tok); + + xfree(recv_tok.value); + + if (GSS_ERROR(status)) { + /* Start again with the next method in the list */ + userauth(authctxt, NULL); + return; + } +} + +void +input_gssapi_errtok(int type, u_int32_t plen, void *ctxt) +{ + Authctxt *authctxt = ctxt; + Gssctxt *gssctxt; + gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; + gss_buffer_desc recv_tok; + OM_uint32 status, ms; + u_int len; + + if (authctxt == NULL) + fatal("input_gssapi_response: no authentication context"); + gssctxt = authctxt->methoddata; + + recv_tok.value = packet_get_string(&len); + recv_tok.length = len; + + packet_check_eom(); + + /* Stick it into GSSAPI and see what it says */ + status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds, + &recv_tok, &send_tok, NULL); + + xfree(recv_tok.value); + gss_release_buffer(&ms, &send_tok); + + /* Server will be returning a failed packet after this one */ +} + +void +input_gssapi_error(int type, u_int32_t plen, void *ctxt) +{ + OM_uint32 maj, min; + char *msg; + char *lang; + + maj=packet_get_int(); + min=packet_get_int(); + msg=packet_get_string(NULL); + lang=packet_get_string(NULL); + + packet_check_eom(); + + debug("Server GSSAPI Error:\n%s", msg); + xfree(msg); + xfree(lang); +} +#endif /* GSSAPI */ + +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[150]; + 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_add_padding(64); + packet_send(); + + dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, + &input_userauth_passwd_changereq); + + return 1; +} +/* + * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST + */ +void +input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt) +{ + Authctxt *authctxt = ctxt; + char *info, *lang, *password = NULL, *retype = NULL; + char prompt[150]; + + debug2("input_userauth_passwd_changereq"); + + if (authctxt == NULL) + fatal("input_userauth_passwd_changereq: " + "no authentication context"); + + info = packet_get_string(NULL); + lang = packet_get_string(NULL); + if (strlen(info) > 0) + logit("%s", info); + xfree(info); + xfree(lang); + 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(1); /* additional info */ + snprintf(prompt, sizeof(prompt), + "Enter %.30s@%.128s's old password: ", + authctxt->server_user, authctxt->host); + password = read_passphrase(prompt, 0); + packet_put_cstring(password); + memset(password, 0, strlen(password)); + xfree(password); + password = NULL; + while (password == NULL) { + snprintf(prompt, sizeof(prompt), + "Enter %.30s@%.128s's new password: ", + authctxt->server_user, authctxt->host); + password = read_passphrase(prompt, RP_ALLOW_EOF); + if (password == NULL) { + /* bail out */ + return; + } + snprintf(prompt, sizeof(prompt), + "Retype %.30s@%.128s's new password: ", + authctxt->server_user, authctxt->host); + retype = read_passphrase(prompt, 0); + if (strcmp(password, retype) != 0) { + memset(password, 0, strlen(password)); + xfree(password); + logit("Mismatch; try again, EOF to quit."); + password = NULL; + } + memset(retype, 0, strlen(retype)); + xfree(retype); + } + packet_put_cstring(password); + memset(password, 0, strlen(password)); + xfree(password); + packet_add_padding(64); + packet_send(); + + dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, + &input_userauth_passwd_changereq); +} + +static int +identity_sign(Identity *id, u_char **sigp, u_int *lenp, + u_char *data, u_int datalen) +{ + Key *prv; + int ret; + + /* the agent supports this key */ + if (id->ac) + return (ssh_agent_sign(id->ac, id->key, sigp, lenp, + data, datalen)); + /* + * we have already loaded the private key or + * the private key is stored in external hardware + */ + if (id->isprivate || (id->key->flags & KEY_FLAG_EXT)) + return (key_sign(id->key, sigp, lenp, data, datalen)); + /* load the private key from the file */ + if ((prv = load_identity_file(id->filename)) == NULL) + return (-1); + ret = key_sign(prv, sigp, lenp, data, datalen); + key_free(prv); + return (ret); +} + +static int +sign_and_send_pubkey(Authctxt *authctxt, Identity *id) +{ + Buffer b; + u_char *blob, *signature; + u_int bloblen, slen; + u_int skip = 0; + int ret = -1; + int have_sig = 1; + + debug3("sign_and_send_pubkey"); + + if (key_to_blob(id->key, &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(id->key)); + } + buffer_put_string(&b, blob, bloblen); + + /* generate signature */ + ret = identity_sign(id, &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(id->key)); + 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; +} + +static int +send_pubkey_test(Authctxt *authctxt, Identity *id) +{ + u_char *blob; + u_int bloblen, have_sig = 0; + + debug3("send_pubkey_test"); + + if (key_to_blob(id->key, &blob, &bloblen) == 0) { + /* we cannot handle this key */ + debug3("send_pubkey_test: cannot handle key"); + return 0; + } + /* register callback for USERAUTH_PK_OK message */ + 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(id->key)); + packet_put_string(blob, bloblen); + xfree(blob); + packet_send(); + return 1; +} + +static Key * +load_identity_file(char *filename) +{ + Key *private; + char prompt[300], *passphrase; + int perm_ok, quit, i; + struct stat st; + + if (stat(filename, &st) < 0) { + debug3("no such identity: %s", filename); + return NULL; + } + private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok); + if (!perm_ok) + return NULL; + if (private == NULL) { + if (options.batch_mode) + 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) { + private = key_load_private_type(KEY_UNSPEC, + filename, passphrase, NULL, NULL); + quit = 0; + } else { + debug2("no passphrase given, try next key"); + quit = 1; + } + memset(passphrase, 0, strlen(passphrase)); + xfree(passphrase); + if (private != NULL || quit) + break; + debug2("bad passphrase given, try again..."); + } + } + return private; +} + +/* + * try keys in the following order: + * 1. agent keys that are found in the config file + * 2. other agent keys + * 3. keys that are only listed in the config file + */ +static void +pubkey_prepare(Authctxt *authctxt) +{ + Identity *id; + Idlist agent, files, *preferred; + Key *key; + AuthenticationConnection *ac; + char *comment; + int i, found; + + TAILQ_INIT(&agent); /* keys from the agent */ + TAILQ_INIT(&files); /* keys from the config file */ + preferred = &authctxt->keys; + TAILQ_INIT(preferred); /* preferred order of keys */ + + /* list of keys stored in the filesystem */ + for (i = 0; i < options.num_identity_files; i++) { + key = options.identity_keys[i]; + if (key && key->type == KEY_RSA1) + continue; + options.identity_keys[i] = NULL; + id = xcalloc(1, sizeof(*id)); + id->key = key; + id->filename = xstrdup(options.identity_files[i]); + TAILQ_INSERT_TAIL(&files, id, next); + } + /* list of keys supported by the agent */ + if ((ac = ssh_get_authentication_connection())) { + for (key = ssh_get_first_identity(ac, &comment, 2); + key != NULL; + key = ssh_get_next_identity(ac, &comment, 2)) { + found = 0; + TAILQ_FOREACH(id, &files, next) { + /* agent keys from the config file are preferred */ + if (key_equal(key, id->key)) { + key_free(key); + xfree(comment); + TAILQ_REMOVE(&files, id, next); + TAILQ_INSERT_TAIL(preferred, id, next); + id->ac = ac; + found = 1; + break; + } + } + if (!found && !options.identities_only) { + id = xcalloc(1, sizeof(*id)); + id->key = key; + id->filename = comment; + id->ac = ac; + TAILQ_INSERT_TAIL(&agent, id, next); + } + } + /* append remaining agent keys */ + for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) { + TAILQ_REMOVE(&agent, id, next); + TAILQ_INSERT_TAIL(preferred, id, next); + } + authctxt->agent = ac; + } + /* append remaining keys from the config file */ + for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) { + TAILQ_REMOVE(&files, id, next); + TAILQ_INSERT_TAIL(preferred, id, next); + } + TAILQ_FOREACH(id, preferred, next) { + debug2("key: %s (%p)", id->filename, id->key); + } +} + +static void +pubkey_cleanup(Authctxt *authctxt) +{ + Identity *id; + + if (authctxt->agent != NULL) + ssh_close_authentication_connection(authctxt->agent); + for (id = TAILQ_FIRST(&authctxt->keys); id; + id = TAILQ_FIRST(&authctxt->keys)) { + TAILQ_REMOVE(&authctxt->keys, id, next); + if (id->key) + key_free(id->key); + if (id->filename) + xfree(id->filename); + xfree(id); + } +} + +int +userauth_pubkey(Authctxt *authctxt) +{ + Identity *id; + int sent = 0; + + while ((id = TAILQ_FIRST(&authctxt->keys))) { + if (id->tried++) + return (0); + /* move key to the end of the queue */ + TAILQ_REMOVE(&authctxt->keys, id, next); + TAILQ_INSERT_TAIL(&authctxt->keys, id, next); + /* + * send a test message if we have the public key. for + * encrypted keys we cannot do this and have to load the + * private key instead + */ + if (id->key && id->key->type != KEY_RSA1) { + debug("Offering public key: %s", id->filename); + sent = send_pubkey_test(authctxt, id); + } else if (id->key == NULL) { + debug("Trying private key: %s", id->filename); + id->key = load_identity_file(id->filename); + if (id->key != NULL) { + id->isprivate = 1; + sent = sign_and_send_pubkey(authctxt, id); + key_free(id->key); + id->key = NULL; + } + } + if (sent) + return (sent); + } + return (0); +} + +/* + * 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; + /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ + if (attempt > 1 && !authctxt->info_req_seen) { + debug3("userauth_kbdint: disable: no info_req_seen"); + dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); + 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, u_int32_t seq, 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"); + + authctxt->info_req_seen = 1; + + name = packet_get_string(NULL); + inst = packet_get_string(NULL); + lang = packet_get_string(NULL); + if (strlen(name) > 0) + logit("%s", name); + if (strlen(inst) > 0) + logit("%s", 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); + + debug2("input_userauth_info_req: num_prompts %d", num_prompts); + for (i = 0; i < num_prompts; i++) { + prompt = packet_get_string(NULL); + echo = packet_get_char(); + + response = read_passphrase(prompt, echo ? RP_ECHO : 0); + + packet_put_cstring(response); + memset(response, 0, strlen(response)); + xfree(response); + xfree(prompt); + } + packet_check_eom(); /* done with parsing incoming message. */ + + packet_add_padding(64); + packet_send(); +} + +static int +ssh_keysign(Key *key, u_char **sigp, u_int *lenp, + u_char *data, u_int datalen) +{ + Buffer b; + struct stat st; + pid_t pid; + int to[2], from[2], status, version = 2; + + debug2("ssh_keysign called"); + + if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { + error("ssh_keysign: no installed: %s", strerror(errno)); + return -1; + } + if (fflush(stdout) != 0) + error("ssh_keysign: fflush: %s", strerror(errno)); + if (pipe(to) < 0) { + error("ssh_keysign: pipe: %s", strerror(errno)); + return -1; + } + if (pipe(from) < 0) { + error("ssh_keysign: pipe: %s", strerror(errno)); + return -1; + } + if ((pid = fork()) < 0) { + error("ssh_keysign: fork: %s", strerror(errno)); + return -1; + } + if (pid == 0) { + permanently_drop_suid(getuid()); + close(from[0]); + if (dup2(from[1], STDOUT_FILENO) < 0) + fatal("ssh_keysign: dup2: %s", strerror(errno)); + close(to[1]); + if (dup2(to[0], STDIN_FILENO) < 0) + fatal("ssh_keysign: dup2: %s", strerror(errno)); + close(from[1]); + close(to[0]); + execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0); + fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN, + strerror(errno)); + } + close(from[1]); + close(to[0]); + + buffer_init(&b); + buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */ + buffer_put_string(&b, data, datalen); + if (ssh_msg_send(to[1], version, &b) == -1) + fatal("ssh_keysign: couldn't send request"); + + if (ssh_msg_recv(from[0], &b) < 0) { + error("ssh_keysign: no reply"); + buffer_free(&b); + return -1; + } + close(from[0]); + close(to[1]); + + while (waitpid(pid, &status, 0) < 0) + if (errno != EINTR) + break; + + if (buffer_get_char(&b) != version) { + error("ssh_keysign: bad version"); + buffer_free(&b); + return -1; + } + *sigp = buffer_get_string(&b, lenp); + buffer_free(&b); + + return 0; +} + +int +userauth_hostbased(Authctxt *authctxt) +{ + Key *private = NULL; + Sensitive *sensitive = authctxt->sensitive; + Buffer b; + u_char *signature, *blob; + char *chost, *pkalg, *p; + const char *service; + u_int blen, slen; + int ok, i, len, found = 0; + + /* check for a useful key */ + for (i = 0; i < sensitive->nkeys; i++) { + private = sensitive->keys[i]; + if (private && private->type != KEY_RSA1) { + found = 1; + /* we take and free the key */ + sensitive->keys[i] = NULL; + break; + } + } + if (!found) { + debug("No more client hostkeys for hostbased authentication."); + return 0; + } + if (key_to_blob(private, &blob, &blen) == 0) { + key_free(private); + return 0; + } + /* figure out a name for the client host */ + p = get_local_name(packet_get_connection_in()); + if (p == NULL) { + error("userauth_hostbased: cannot get local ipaddr/name"); + key_free(private); + xfree(blob); + return 0; + } + len = strlen(p) + 2; + xasprintf(&chost, "%s.", p); + debug2("userauth_hostbased: chost %s", chost); + xfree(p); + + service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : + authctxt->service; + pkalg = xstrdup(key_ssh_name(private)); + buffer_init(&b); + /* construct data */ + buffer_put_string(&b, session_id2, session_id2_len); + buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); + buffer_put_cstring(&b, authctxt->server_user); + buffer_put_cstring(&b, service); + buffer_put_cstring(&b, authctxt->method->name); + buffer_put_cstring(&b, pkalg); + buffer_put_string(&b, blob, blen); + buffer_put_cstring(&b, chost); + buffer_put_cstring(&b, authctxt->local_user); +#ifdef DEBUG_PK + buffer_dump(&b); +#endif + if (sensitive->external_keysign) + ok = ssh_keysign(private, &signature, &slen, + buffer_ptr(&b), buffer_len(&b)); + else + ok = key_sign(private, &signature, &slen, + buffer_ptr(&b), buffer_len(&b)); + key_free(private); + buffer_free(&b); + if (ok != 0) { + error("key_sign failed"); + xfree(chost); + xfree(pkalg); + xfree(blob); + return 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_cstring(pkalg); + packet_put_string(blob, blen); + packet_put_cstring(chost); + packet_put_cstring(authctxt->local_user); + packet_put_string(signature, slen); + memset(signature, 's', slen); + xfree(signature); + xfree(chost); + xfree(pkalg); + xfree(blob); + + packet_send(); + return 1; +} + +/* find auth method */ + +/* + * given auth method name, if configurable options permit this method fill + * in auth_ident field and return true, otherwise return false. + */ +static 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; +} + +static 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; +} + +/* XXX internal state */ +static Authmethod *current = NULL; +static char *supported = NULL; +static char *preferred = 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. + */ +static Authmethod * +authmethod_get(char *authlist) +{ + char *name = NULL; + u_int next; + + /* Use a suitable default if we're passed a nil list. */ + if (authlist == NULL || strlen(authlist) == 0) + authlist = options.preferred_authentications; + + if (supported == NULL || strcmp(authlist, supported) != 0) { + debug3("start over, passed a different list %s", authlist); + if (supported != NULL) + xfree(supported); + supported = xstrdup(authlist); + preferred = options.preferred_authentications; + debug3("preferred %s", preferred); + current = NULL; + } else if (current != NULL && authmethod_is_enabled(current)) + return current; + + for (;;) { + if ((name = match_list(preferred, supported, &next)) == NULL) { + debug("No more authentication methods to try."); + current = NULL; + return NULL; + } + preferred += next; + debug3("authmethod_lookup %s", name); + debug3("remaining preferred: %s", preferred); + if ((current = authmethod_lookup(name)) != NULL && + authmethod_is_enabled(current)) { + debug3("authmethod_is_enabled %s", name); + debug("Next authentication method: %s", name); + return current; + } + } +} + +static char * +authmethods_get(void) +{ + Authmethod *method = NULL; + Buffer b; + char *list; + + buffer_init(&b); + for (method = authmethods; method->name != NULL; method++) { + if (authmethod_is_enabled(method)) { + if (buffer_len(&b) > 0) + buffer_append(&b, ",", 1); + buffer_append(&b, method->name, strlen(method->name)); + } + } + buffer_append(&b, "\0", 1); + list = xstrdup(buffer_ptr(&b)); + buffer_free(&b); + return list; +} |
