diff options
Diffstat (limited to 'auth2.c')
| -rw-r--r-- | auth2.c | 847 |
1 files changed, 847 insertions, 0 deletions
@@ -0,0 +1,847 @@ +/* $OpenBSD: auth2.c,v 1.164 2022/02/23 11:18:13 djm 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/stat.h> +#include <sys/uio.h> + +#include <fcntl.h> +#include <limits.h> +#include <pwd.h> +#include <stdarg.h> +#include <string.h> +#include <unistd.h> +#include <time.h> + +#include "stdlib.h" +#include "atomicio.h" +#include "xmalloc.h" +#include "ssh2.h" +#include "packet.h" +#include "log.h" +#include "sshbuf.h" +#include "misc.h" +#include "servconf.h" +#include "compat.h" +#include "sshkey.h" +#include "hostfile.h" +#include "auth.h" +#include "dispatch.h" +#include "pathnames.h" +#include "ssherr.h" +#ifdef GSSAPI +#include "ssh-gss.h" +#endif +#include "monitor_wrap.h" +#include "digest.h" + +/* import */ +extern ServerOptions options; +extern struct sshbuf *loginmsg; + +/* methods */ + +extern Authmethod method_none; +extern Authmethod method_pubkey; +extern Authmethod method_passwd; +extern Authmethod method_kbdint; +extern Authmethod method_hostbased; +#ifdef GSSAPI +extern Authmethod method_gssapi; +#endif + +Authmethod *authmethods[] = { + &method_none, + &method_pubkey, +#ifdef GSSAPI + &method_gssapi, +#endif + &method_passwd, + &method_kbdint, + &method_hostbased, + NULL +}; + +/* protocol */ + +static int input_service_request(int, u_int32_t, struct ssh *); +static int input_userauth_request(int, u_int32_t, struct ssh *); + +/* helper */ +static Authmethod *authmethod_byname(const char *); +static Authmethod *authmethod_lookup(Authctxt *, const char *); +static char *authmethods_get(Authctxt *authctxt); + +#define MATCH_NONE 0 /* method or submethod mismatch */ +#define MATCH_METHOD 1 /* method matches (no submethod specified) */ +#define MATCH_BOTH 2 /* method and submethod match */ +#define MATCH_PARTIAL 3 /* method matches, submethod can't be checked */ +static int list_starts_with(const char *, const char *, const char *); + +char * +auth2_read_banner(void) +{ + struct stat st; + char *banner = NULL; + size_t len, n; + int fd; + + if ((fd = open(options.banner, O_RDONLY)) == -1) + return (NULL); + if (fstat(fd, &st) == -1) { + close(fd); + return (NULL); + } + if (st.st_size <= 0 || st.st_size > 1*1024*1024) { + close(fd); + return (NULL); + } + + len = (size_t)st.st_size; /* truncate */ + banner = xmalloc(len + 1); + n = atomicio(read, fd, banner, len); + close(fd); + + if (n != len) { + free(banner); + return (NULL); + } + banner[n] = '\0'; + + return (banner); +} + +static void +userauth_send_banner(struct ssh *ssh, const char *msg) +{ + int r; + + if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_BANNER)) != 0 || + (r = sshpkt_put_cstring(ssh, msg)) != 0 || + (r = sshpkt_put_cstring(ssh, "")) != 0 || /* language, unused */ + (r = sshpkt_send(ssh)) != 0) + fatal_fr(r, "send packet"); + debug("%s: sent", __func__); +} + +static void +userauth_banner(struct ssh *ssh) +{ + char *banner = NULL; + + if (options.banner == NULL) + return; + + if ((banner = PRIVSEP(auth2_read_banner())) == NULL) + goto done; + userauth_send_banner(ssh, banner); + +done: + free(banner); +} + +/* + * loop until authctxt->success == TRUE + */ +void +do_authentication2(struct ssh *ssh) +{ + Authctxt *authctxt = ssh->authctxt; + + ssh_dispatch_init(ssh, &dispatch_protocol_error); + ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_REQUEST, &input_service_request); + ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt->success); + ssh->authctxt = NULL; +} + +/*ARGSUSED*/ +static int +input_service_request(int type, u_int32_t seq, struct ssh *ssh) +{ + Authctxt *authctxt = ssh->authctxt; + char *service = NULL; + int r, acceptit = 0; + + if ((r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 || + (r = sshpkt_get_end(ssh)) != 0) + goto out; + + if (authctxt == NULL) + fatal("input_service_request: no authctxt"); + + if (strcmp(service, "ssh-userauth") == 0) { + if (!authctxt->success) { + acceptit = 1; + /* now we can handle user-auth requests */ + ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, + &input_userauth_request); + } + } + /* XXX all other service requests are denied */ + + if (acceptit) { + if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_ACCEPT)) != 0 || + (r = sshpkt_put_cstring(ssh, service)) != 0 || + (r = sshpkt_send(ssh)) != 0 || + (r = ssh_packet_write_wait(ssh)) != 0) + goto out; + } else { + debug("bad service request %s", service); + ssh_packet_disconnect(ssh, "bad service request %s", service); + } + r = 0; + out: + free(service); + return r; +} + +#define MIN_FAIL_DELAY_SECONDS 0.005 +static double +user_specific_delay(const char *user) +{ + char b[512]; + size_t len = ssh_digest_bytes(SSH_DIGEST_SHA512); + u_char *hash = xmalloc(len); + double delay; + + (void)snprintf(b, sizeof b, "%llu%s", + (unsigned long long)options.timing_secret, user); + if (ssh_digest_memory(SSH_DIGEST_SHA512, b, strlen(b), hash, len) != 0) + fatal_f("ssh_digest_memory"); + /* 0-4.2 ms of delay */ + delay = (double)PEEK_U32(hash) / 1000 / 1000 / 1000 / 1000; + freezero(hash, len); + debug3_f("user specific delay %0.3lfms", delay/1000); + return MIN_FAIL_DELAY_SECONDS + delay; +} + +static void +ensure_minimum_time_since(double start, double seconds) +{ + struct timespec ts; + double elapsed = monotime_double() - start, req = seconds, remain; + + /* if we've already passed the requested time, scale up */ + while ((remain = seconds - elapsed) < 0.0) + seconds *= 2; + + ts.tv_sec = remain; + ts.tv_nsec = (remain - ts.tv_sec) * 1000000000; + debug3_f("elapsed %0.3lfms, delaying %0.3lfms (requested %0.3lfms)", + elapsed*1000, remain*1000, req*1000); + nanosleep(&ts, NULL); +} + +/*ARGSUSED*/ +static int +input_userauth_request(int type, u_int32_t seq, struct ssh *ssh) +{ + Authctxt *authctxt = ssh->authctxt; + Authmethod *m = NULL; + char *user = NULL, *service = NULL, *method = NULL, *style = NULL; + int r, authenticated = 0; + double tstart = monotime_double(); + + if (authctxt == NULL) + fatal("input_userauth_request: no authctxt"); + + if ((r = sshpkt_get_cstring(ssh, &user, NULL)) != 0 || + (r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 || + (r = sshpkt_get_cstring(ssh, &method, NULL)) != 0) + goto out; + debug("userauth-request for user %s service %s method %s", user, service, method); + debug("attempt %d failures %d", authctxt->attempt, authctxt->failures); + + if ((style = strchr(user, ':')) != NULL) + *style++ = 0; + + if (authctxt->attempt >= 1024) + auth_maxtries_exceeded(ssh); + if (authctxt->attempt++ == 0) { + /* setup auth context */ + authctxt->pw = PRIVSEP(getpwnamallow(ssh, user)); + authctxt->user = xstrdup(user); + if (authctxt->pw && strcmp(service, "ssh-connection")==0) { + authctxt->valid = 1; + debug2_f("setting up authctxt for %s", user); + } else { + authctxt->valid = 0; + /* Invalid user, fake password information */ + authctxt->pw = fakepw(); +#ifdef SSH_AUDIT_EVENTS + PRIVSEP(audit_event(ssh, SSH_INVALID_USER)); +#endif + } +#ifdef USE_PAM + if (options.use_pam) + PRIVSEP(start_pam(ssh)); +#endif + ssh_packet_set_log_preamble(ssh, "%suser %s", + authctxt->valid ? "authenticating " : "invalid ", user); + setproctitle("%s%s", authctxt->valid ? user : "unknown", + use_privsep ? " [net]" : ""); + authctxt->service = xstrdup(service); + authctxt->style = style ? xstrdup(style) : NULL; + if (use_privsep) + mm_inform_authserv(service, style); + userauth_banner(ssh); + if (auth2_setup_methods_lists(authctxt) != 0) + ssh_packet_disconnect(ssh, + "no authentication methods enabled"); + } else if (strcmp(user, authctxt->user) != 0 || + strcmp(service, authctxt->service) != 0) { + ssh_packet_disconnect(ssh, "Change of username or service " + "not allowed: (%s,%s) -> (%s,%s)", + authctxt->user, authctxt->service, user, service); + } + /* reset state */ + auth2_challenge_stop(ssh); + +#ifdef GSSAPI + /* XXX move to auth2_gssapi_stop() */ + ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); + ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); +#endif + + auth2_authctxt_reset_info(authctxt); + authctxt->postponed = 0; + authctxt->server_caused_failure = 0; + + /* try to authenticate user */ + m = authmethod_lookup(authctxt, method); + if (m != NULL && authctxt->failures < options.max_authtries) { + debug2("input_userauth_request: try method %s", method); + authenticated = m->userauth(ssh, method); + } + if (!authctxt->authenticated) + ensure_minimum_time_since(tstart, + user_specific_delay(authctxt->user)); + userauth_finish(ssh, authenticated, method, NULL); + r = 0; + out: + free(service); + free(user); + free(method); + return r; +} + +void +userauth_finish(struct ssh *ssh, int authenticated, const char *packet_method, + const char *submethod) +{ + Authctxt *authctxt = ssh->authctxt; + Authmethod *m = NULL; + const char *method = packet_method; + char *methods; + int r, partial = 0; + + if (authenticated) { + if (!authctxt->valid) { + fatal("INTERNAL ERROR: authenticated invalid user %s", + authctxt->user); + } + if (authctxt->postponed) + fatal("INTERNAL ERROR: authenticated and postponed"); + /* prefer primary authmethod name to possible synonym */ + if ((m = authmethod_byname(method)) == NULL) + fatal("INTERNAL ERROR: bad method %s", method); + method = m->name; + } + + /* Special handling for root */ + if (authenticated && authctxt->pw->pw_uid == 0 && + !auth_root_allowed(ssh, method)) { + authenticated = 0; +#ifdef SSH_AUDIT_EVENTS + PRIVSEP(audit_event(ssh, SSH_LOGIN_ROOT_DENIED)); +#endif + } + + if (authenticated && options.num_auth_methods != 0) { + if (!auth2_update_methods_lists(authctxt, method, submethod)) { + authenticated = 0; + partial = 1; + } + } + + /* Log before sending the reply */ + auth_log(ssh, authenticated, partial, method, submethod); + + /* Update information exposed to session */ + if (authenticated || partial) + auth2_update_session_info(authctxt, method, submethod); + + if (authctxt->postponed) + return; + +#ifdef USE_PAM + if (options.use_pam && authenticated) { + int r, success = PRIVSEP(do_pam_account()); + + /* If PAM returned a message, send it to the user. */ + if (sshbuf_len(loginmsg) > 0) { + if ((r = sshbuf_put(loginmsg, "\0", 1)) != 0) + fatal("%s: buffer error: %s", + __func__, ssh_err(r)); + userauth_send_banner(ssh, sshbuf_ptr(loginmsg)); + if ((r = ssh_packet_write_wait(ssh)) != 0) { + sshpkt_fatal(ssh, r, + "%s: send PAM banner", __func__); + } + } + if (!success) { + fatal("Access denied for user %s by PAM account " + "configuration", authctxt->user); + } + } +#endif + + if (authenticated == 1) { + /* turn off userauth */ + ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, + &dispatch_protocol_ignore); + if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_SUCCESS)) != 0 || + (r = sshpkt_send(ssh)) != 0 || + (r = ssh_packet_write_wait(ssh)) != 0) + fatal_fr(r, "send success packet"); + /* now we can break out */ + authctxt->success = 1; + ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user); + } else { + /* Allow initial try of "none" auth without failure penalty */ + if (!partial && !authctxt->server_caused_failure && + (authctxt->attempt > 1 || strcmp(method, "none") != 0)) + authctxt->failures++; + if (authctxt->failures >= options.max_authtries) { +#ifdef SSH_AUDIT_EVENTS + PRIVSEP(audit_event(ssh, SSH_LOGIN_EXCEED_MAXTRIES)); +#endif + auth_maxtries_exceeded(ssh); + } + methods = authmethods_get(authctxt); + debug3_f("failure partial=%d next methods=\"%s\"", + partial, methods); + if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_FAILURE)) != 0 || + (r = sshpkt_put_cstring(ssh, methods)) != 0 || + (r = sshpkt_put_u8(ssh, partial)) != 0 || + (r = sshpkt_send(ssh)) != 0 || + (r = ssh_packet_write_wait(ssh)) != 0) + fatal_fr(r, "send failure packet"); + free(methods); + } +} + +/* + * Checks whether method is allowed by at least one AuthenticationMethods + * methods list. Returns 1 if allowed, or no methods lists configured. + * 0 otherwise. + */ +int +auth2_method_allowed(Authctxt *authctxt, const char *method, + const char *submethod) +{ + u_int i; + + /* + * NB. authctxt->num_auth_methods might be zero as a result of + * auth2_setup_methods_lists(), so check the configuration. + */ + if (options.num_auth_methods == 0) + return 1; + for (i = 0; i < authctxt->num_auth_methods; i++) { + if (list_starts_with(authctxt->auth_methods[i], method, + submethod) != MATCH_NONE) + return 1; + } + return 0; +} + +static char * +authmethods_get(Authctxt *authctxt) +{ + struct sshbuf *b; + char *list; + int i, r; + + if ((b = sshbuf_new()) == NULL) + fatal_f("sshbuf_new failed"); + for (i = 0; authmethods[i] != NULL; i++) { + if (strcmp(authmethods[i]->name, "none") == 0) + continue; + if (authmethods[i]->enabled == NULL || + *(authmethods[i]->enabled) == 0) + continue; + if (!auth2_method_allowed(authctxt, authmethods[i]->name, + NULL)) + continue; + if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) ? "," : "", + authmethods[i]->name)) != 0) + fatal_fr(r, "buffer error"); + } + if ((list = sshbuf_dup_string(b)) == NULL) + fatal_f("sshbuf_dup_string failed"); + sshbuf_free(b); + return list; +} + +static Authmethod * +authmethod_byname(const char *name) +{ + int i; + + if (name == NULL) + fatal_f("NULL authentication method name"); + for (i = 0; authmethods[i] != NULL; i++) { + if (strcmp(name, authmethods[i]->name) == 0 || + (authmethods[i]->synonym != NULL && + strcmp(name, authmethods[i]->synonym) == 0)) + return authmethods[i]; + } + debug_f("unrecognized authentication method name: %s", name); + return NULL; +} + +static Authmethod * +authmethod_lookup(Authctxt *authctxt, const char *name) +{ + Authmethod *method; + + if ((method = authmethod_byname(name)) == NULL) + return NULL; + + if (method->enabled == NULL || *(method->enabled) == 0) { + debug3_f("method %s not enabled", name); + return NULL; + } + if (!auth2_method_allowed(authctxt, method->name, NULL)) { + debug3_f("method %s not allowed " + "by AuthenticationMethods", name); + return NULL; + } + return method; +} + +/* + * Check a comma-separated list of methods for validity. Is need_enable is + * non-zero, then also require that the methods are enabled. + * Returns 0 on success or -1 if the methods list is invalid. + */ +int +auth2_methods_valid(const char *_methods, int need_enable) +{ + char *methods, *omethods, *method, *p; + u_int i, found; + int ret = -1; + + if (*_methods == '\0') { + error("empty authentication method list"); + return -1; + } + omethods = methods = xstrdup(_methods); + while ((method = strsep(&methods, ",")) != NULL) { + for (found = i = 0; !found && authmethods[i] != NULL; i++) { + if ((p = strchr(method, ':')) != NULL) + *p = '\0'; + if (strcmp(method, authmethods[i]->name) != 0) + continue; + if (need_enable) { + if (authmethods[i]->enabled == NULL || + *(authmethods[i]->enabled) == 0) { + error("Disabled method \"%s\" in " + "AuthenticationMethods list \"%s\"", + method, _methods); + goto out; + } + } + found = 1; + break; + } + if (!found) { + error("Unknown authentication method \"%s\" in list", + method); + goto out; + } + } + ret = 0; + out: + free(omethods); + return ret; +} + +/* + * Prune the AuthenticationMethods supplied in the configuration, removing + * any methods lists that include disabled methods. Note that this might + * leave authctxt->num_auth_methods == 0, even when multiple required auth + * has been requested. For this reason, all tests for whether multiple is + * enabled should consult options.num_auth_methods directly. + */ +int +auth2_setup_methods_lists(Authctxt *authctxt) +{ + u_int i; + + /* First, normalise away the "any" pseudo-method */ + if (options.num_auth_methods == 1 && + strcmp(options.auth_methods[0], "any") == 0) { + free(options.auth_methods[0]); + options.auth_methods[0] = NULL; + options.num_auth_methods = 0; + } + + if (options.num_auth_methods == 0) + return 0; + debug3_f("checking methods"); + authctxt->auth_methods = xcalloc(options.num_auth_methods, + sizeof(*authctxt->auth_methods)); + authctxt->num_auth_methods = 0; + for (i = 0; i < options.num_auth_methods; i++) { + if (auth2_methods_valid(options.auth_methods[i], 1) != 0) { + logit("Authentication methods list \"%s\" contains " + "disabled method, skipping", + options.auth_methods[i]); + continue; + } + debug("authentication methods list %d: %s", + authctxt->num_auth_methods, options.auth_methods[i]); + authctxt->auth_methods[authctxt->num_auth_methods++] = + xstrdup(options.auth_methods[i]); + } + if (authctxt->num_auth_methods == 0) { + error("No AuthenticationMethods left after eliminating " + "disabled methods"); + return -1; + } + return 0; +} + +static int +list_starts_with(const char *methods, const char *method, + const char *submethod) +{ + size_t l = strlen(method); + int match; + const char *p; + + if (strncmp(methods, method, l) != 0) + return MATCH_NONE; + p = methods + l; + match = MATCH_METHOD; + if (*p == ':') { + if (!submethod) + return MATCH_PARTIAL; + l = strlen(submethod); + p += 1; + if (strncmp(submethod, p, l)) + return MATCH_NONE; + p += l; + match = MATCH_BOTH; + } + if (*p != ',' && *p != '\0') + return MATCH_NONE; + return match; +} + +/* + * Remove method from the start of a comma-separated list of methods. + * Returns 0 if the list of methods did not start with that method or 1 + * if it did. + */ +static int +remove_method(char **methods, const char *method, const char *submethod) +{ + char *omethods = *methods, *p; + size_t l = strlen(method); + int match; + + match = list_starts_with(omethods, method, submethod); + if (match != MATCH_METHOD && match != MATCH_BOTH) + return 0; + p = omethods + l; + if (submethod && match == MATCH_BOTH) + p += 1 + strlen(submethod); /* include colon */ + if (*p == ',') + p++; + *methods = xstrdup(p); + free(omethods); + return 1; +} + +/* + * Called after successful authentication. Will remove the successful method + * from the start of each list in which it occurs. If it was the last method + * in any list, then authentication is deemed successful. + * Returns 1 if the method completed any authentication list or 0 otherwise. + */ +int +auth2_update_methods_lists(Authctxt *authctxt, const char *method, + const char *submethod) +{ + u_int i, found = 0; + + debug3_f("updating methods list after \"%s\"", method); + for (i = 0; i < authctxt->num_auth_methods; i++) { + if (!remove_method(&(authctxt->auth_methods[i]), method, + submethod)) + continue; + found = 1; + if (*authctxt->auth_methods[i] == '\0') { + debug2("authentication methods list %d complete", i); + return 1; + } + debug3("authentication methods list %d remaining: \"%s\"", + i, authctxt->auth_methods[i]); + } + /* This should not happen, but would be bad if it did */ + if (!found) + fatal_f("method not in AuthenticationMethods"); + return 0; +} + +/* Reset method-specific information */ +void auth2_authctxt_reset_info(Authctxt *authctxt) +{ + sshkey_free(authctxt->auth_method_key); + free(authctxt->auth_method_info); + authctxt->auth_method_key = NULL; + authctxt->auth_method_info = NULL; +} + +/* Record auth method-specific information for logs */ +void +auth2_record_info(Authctxt *authctxt, const char *fmt, ...) +{ + va_list ap; + int i; + + free(authctxt->auth_method_info); + authctxt->auth_method_info = NULL; + + va_start(ap, fmt); + i = vasprintf(&authctxt->auth_method_info, fmt, ap); + va_end(ap); + + if (i == -1) + fatal_f("vasprintf failed"); +} + +/* + * Records a public key used in authentication. This is used for logging + * and to ensure that the same key is not subsequently accepted again for + * multiple authentication. + */ +void +auth2_record_key(Authctxt *authctxt, int authenticated, + const struct sshkey *key) +{ + struct sshkey **tmp, *dup; + int r; + + if ((r = sshkey_from_private(key, &dup)) != 0) + fatal_fr(r, "copy key"); + sshkey_free(authctxt->auth_method_key); + authctxt->auth_method_key = dup; + + if (!authenticated) + return; + + /* If authenticated, make sure we don't accept this key again */ + if ((r = sshkey_from_private(key, &dup)) != 0) + fatal_fr(r, "copy key"); + if (authctxt->nprev_keys >= INT_MAX || + (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys, + authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL) + fatal_f("reallocarray failed"); + authctxt->prev_keys = tmp; + authctxt->prev_keys[authctxt->nprev_keys] = dup; + authctxt->nprev_keys++; + +} + +/* Checks whether a key has already been previously used for authentication */ +int +auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key) +{ + u_int i; + char *fp; + + for (i = 0; i < authctxt->nprev_keys; i++) { + if (sshkey_equal_public(key, authctxt->prev_keys[i])) { + fp = sshkey_fingerprint(authctxt->prev_keys[i], + options.fingerprint_hash, SSH_FP_DEFAULT); + debug3_f("key already used: %s %s", + sshkey_type(authctxt->prev_keys[i]), + fp == NULL ? "UNKNOWN" : fp); + free(fp); + return 1; + } + } + return 0; +} + +/* + * Updates authctxt->session_info with details of authentication. Should be + * whenever an authentication method succeeds. + */ +void +auth2_update_session_info(Authctxt *authctxt, const char *method, + const char *submethod) +{ + int r; + + if (authctxt->session_info == NULL) { + if ((authctxt->session_info = sshbuf_new()) == NULL) + fatal_f("sshbuf_new"); + } + + /* Append method[/submethod] */ + if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s", + method, submethod == NULL ? "" : "/", + submethod == NULL ? "" : submethod)) != 0) + fatal_fr(r, "append method"); + + /* Append key if present */ + if (authctxt->auth_method_key != NULL) { + if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || + (r = sshkey_format_text(authctxt->auth_method_key, + authctxt->session_info)) != 0) + fatal_fr(r, "append key"); + } + + if (authctxt->auth_method_info != NULL) { + /* Ensure no ambiguity here */ + if (strchr(authctxt->auth_method_info, '\n') != NULL) + fatal_f("auth_method_info contains \\n"); + if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || + (r = sshbuf_putf(authctxt->session_info, "%s", + authctxt->auth_method_info)) != 0) { + fatal_fr(r, "append method info"); + } + } + if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0) + fatal_fr(r, "append"); +} + |