| /* $OpenBSD: auth.c,v 1.129 2018/06/01 03:33:53 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/socket.h> |
| #include <sys/wait.h> |
| |
| #include <netinet/in.h> |
| |
| #include <errno.h> |
| #include <fcntl.h> |
| #ifdef HAVE_PATHS_H |
| # include <paths.h> |
| #endif |
| #include <pwd.h> |
| #ifdef HAVE_LOGIN_H |
| #include <login.h> |
| #endif |
| #ifdef USE_SHADOW |
| #include <shadow.h> |
| #endif |
| #include <stdarg.h> |
| #include <stdio.h> |
| #include <string.h> |
| #include <unistd.h> |
| #include <limits.h> |
| #include <netdb.h> |
| |
| #include "xmalloc.h" |
| #include "match.h" |
| #include "groupaccess.h" |
| #include "log.h" |
| #include "buffer.h" |
| #include "misc.h" |
| #include "servconf.h" |
| #include "key.h" |
| #include "hostfile.h" |
| #include "auth.h" |
| #include "auth-options.h" |
| #include "canohost.h" |
| #include "uidswap.h" |
| #include "packet.h" |
| #include "loginrec.h" |
| #ifdef GSSAPI |
| #include "ssh-gss.h" |
| #endif |
| #include "authfile.h" |
| #include "monitor_wrap.h" |
| #include "authfile.h" |
| #include "ssherr.h" |
| #include "compat.h" |
| #include "channels.h" |
| |
| /* import */ |
| extern ServerOptions options; |
| extern int use_privsep; |
| extern Buffer loginmsg; |
| extern struct passwd *privsep_pw; |
| extern struct sshauthopt *auth_opts; |
| |
| /* Debugging messages */ |
| Buffer auth_debug; |
| int auth_debug_init; |
| |
| /* |
| * Check if the user is allowed to log in via ssh. If user is listed |
| * in DenyUsers or one of user's groups is listed in DenyGroups, false |
| * will be returned. If AllowUsers isn't empty and user isn't listed |
| * there, or if AllowGroups isn't empty and one of user's groups isn't |
| * listed there, false will be returned. |
| * If the user's shell is not executable, false will be returned. |
| * Otherwise true is returned. |
| */ |
| int |
| allowed_user(struct passwd * pw) |
| { |
| struct ssh *ssh = active_state; /* XXX */ |
| struct stat st; |
| const char *hostname = NULL, *ipaddr = NULL, *passwd = NULL; |
| u_int i; |
| int r; |
| #ifdef USE_SHADOW |
| struct spwd *spw = NULL; |
| #endif |
| |
| /* Shouldn't be called if pw is NULL, but better safe than sorry... */ |
| if (!pw || !pw->pw_name) |
| return 0; |
| |
| #ifdef USE_SHADOW |
| if (!options.use_pam) |
| spw = getspnam(pw->pw_name); |
| #ifdef HAS_SHADOW_EXPIRE |
| if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw)) |
| return 0; |
| #endif /* HAS_SHADOW_EXPIRE */ |
| #endif /* USE_SHADOW */ |
| |
| /* grab passwd field for locked account check */ |
| passwd = pw->pw_passwd; |
| #ifdef USE_SHADOW |
| if (spw != NULL) |
| #ifdef USE_LIBIAF |
| passwd = get_iaf_password(pw); |
| #else |
| passwd = spw->sp_pwdp; |
| #endif /* USE_LIBIAF */ |
| #endif |
| |
| /* check for locked account */ |
| if (!options.use_pam && passwd && *passwd) { |
| int locked = 0; |
| |
| #ifdef LOCKED_PASSWD_STRING |
| if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0) |
| locked = 1; |
| #endif |
| #ifdef LOCKED_PASSWD_PREFIX |
| if (strncmp(passwd, LOCKED_PASSWD_PREFIX, |
| strlen(LOCKED_PASSWD_PREFIX)) == 0) |
| locked = 1; |
| #endif |
| #ifdef LOCKED_PASSWD_SUBSTR |
| if (strstr(passwd, LOCKED_PASSWD_SUBSTR)) |
| locked = 1; |
| #endif |
| #ifdef USE_LIBIAF |
| free((void *) passwd); |
| #endif /* USE_LIBIAF */ |
| if (locked) { |
| logit("User %.100s not allowed because account is locked", |
| pw->pw_name); |
| return 0; |
| } |
| } |
| |
| /* |
| * Deny if shell does not exist or is not executable unless we |
| * are chrooting. |
| */ |
| if (options.chroot_directory == NULL || |
| strcasecmp(options.chroot_directory, "none") == 0) { |
| char *shell = xstrdup((pw->pw_shell[0] == '\0') ? |
| _PATH_BSHELL : pw->pw_shell); /* empty = /bin/sh */ |
| |
| if (stat(shell, &st) != 0) { |
| logit("User %.100s not allowed because shell %.100s " |
| "does not exist", pw->pw_name, shell); |
| free(shell); |
| return 0; |
| } |
| if (S_ISREG(st.st_mode) == 0 || |
| (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) { |
| logit("User %.100s not allowed because shell %.100s " |
| "is not executable", pw->pw_name, shell); |
| free(shell); |
| return 0; |
| } |
| free(shell); |
| } |
| |
| if (options.num_deny_users > 0 || options.num_allow_users > 0 || |
| options.num_deny_groups > 0 || options.num_allow_groups > 0) { |
| hostname = auth_get_canonical_hostname(ssh, options.use_dns); |
| ipaddr = ssh_remote_ipaddr(ssh); |
| } |
| |
| /* Return false if user is listed in DenyUsers */ |
| if (options.num_deny_users > 0) { |
| for (i = 0; i < options.num_deny_users; i++) { |
| r = match_user(pw->pw_name, hostname, ipaddr, |
| options.deny_users[i]); |
| if (r < 0) { |
| fatal("Invalid DenyUsers pattern \"%.100s\"", |
| options.deny_users[i]); |
| } else if (r != 0) { |
| logit("User %.100s from %.100s not allowed " |
| "because listed in DenyUsers", |
| pw->pw_name, hostname); |
| return 0; |
| } |
| } |
| } |
| /* Return false if AllowUsers isn't empty and user isn't listed there */ |
| if (options.num_allow_users > 0) { |
| for (i = 0; i < options.num_allow_users; i++) { |
| r = match_user(pw->pw_name, hostname, ipaddr, |
| options.allow_users[i]); |
| if (r < 0) { |
| fatal("Invalid AllowUsers pattern \"%.100s\"", |
| options.allow_users[i]); |
| } else if (r == 1) |
| break; |
| } |
| /* i < options.num_allow_users iff we break for loop */ |
| if (i >= options.num_allow_users) { |
| logit("User %.100s from %.100s not allowed because " |
| "not listed in AllowUsers", pw->pw_name, hostname); |
| return 0; |
| } |
| } |
| if (options.num_deny_groups > 0 || options.num_allow_groups > 0) { |
| /* Get the user's group access list (primary and supplementary) */ |
| if (ga_init(pw->pw_name, pw->pw_gid) == 0) { |
| logit("User %.100s from %.100s not allowed because " |
| "not in any group", pw->pw_name, hostname); |
| return 0; |
| } |
| |
| /* Return false if one of user's groups is listed in DenyGroups */ |
| if (options.num_deny_groups > 0) |
| if (ga_match(options.deny_groups, |
| options.num_deny_groups)) { |
| ga_free(); |
| logit("User %.100s from %.100s not allowed " |
| "because a group is listed in DenyGroups", |
| pw->pw_name, hostname); |
| return 0; |
| } |
| /* |
| * Return false if AllowGroups isn't empty and one of user's groups |
| * isn't listed there |
| */ |
| if (options.num_allow_groups > 0) |
| if (!ga_match(options.allow_groups, |
| options.num_allow_groups)) { |
| ga_free(); |
| logit("User %.100s from %.100s not allowed " |
| "because none of user's groups are listed " |
| "in AllowGroups", pw->pw_name, hostname); |
| return 0; |
| } |
| ga_free(); |
| } |
| |
| #ifdef CUSTOM_SYS_AUTH_ALLOWED_USER |
| if (!sys_auth_allowed_user(pw, &loginmsg)) |
| return 0; |
| #endif |
| |
| /* We found no reason not to let this user try to log on... */ |
| return 1; |
| } |
| |
| /* |
| * Formats any key left in authctxt->auth_method_key for inclusion in |
| * auth_log()'s message. Also includes authxtct->auth_method_info if present. |
| */ |
| static char * |
| format_method_key(Authctxt *authctxt) |
| { |
| const struct sshkey *key = authctxt->auth_method_key; |
| const char *methinfo = authctxt->auth_method_info; |
| char *fp, *ret = NULL; |
| |
| if (key == NULL) |
| return NULL; |
| |
| if (key_is_cert(key)) { |
| fp = sshkey_fingerprint(key->cert->signature_key, |
| options.fingerprint_hash, SSH_FP_DEFAULT); |
| xasprintf(&ret, "%s ID %s (serial %llu) CA %s %s%s%s", |
| sshkey_type(key), key->cert->key_id, |
| (unsigned long long)key->cert->serial, |
| sshkey_type(key->cert->signature_key), |
| fp == NULL ? "(null)" : fp, |
| methinfo == NULL ? "" : ", ", |
| methinfo == NULL ? "" : methinfo); |
| free(fp); |
| } else { |
| fp = sshkey_fingerprint(key, options.fingerprint_hash, |
| SSH_FP_DEFAULT); |
| xasprintf(&ret, "%s %s%s%s", sshkey_type(key), |
| fp == NULL ? "(null)" : fp, |
| methinfo == NULL ? "" : ", ", |
| methinfo == NULL ? "" : methinfo); |
| free(fp); |
| } |
| return ret; |
| } |
| |
| void |
| auth_log(Authctxt *authctxt, int authenticated, int partial, |
| const char *method, const char *submethod) |
| { |
| struct ssh *ssh = active_state; /* XXX */ |
| void (*authlog) (const char *fmt,...) = verbose; |
| const char *authmsg; |
| char *extra = NULL; |
| |
| if (use_privsep && !mm_is_monitor() && !authctxt->postponed) |
| return; |
| |
| /* Raise logging level */ |
| if (authenticated == 1 || |
| !authctxt->valid || |
| authctxt->failures >= options.max_authtries / 2 || |
| strcmp(method, "password") == 0) |
| authlog = logit; |
| |
| if (authctxt->postponed) |
| authmsg = "Postponed"; |
| else if (partial) |
| authmsg = "Partial"; |
| else |
| authmsg = authenticated ? "Accepted" : "Failed"; |
| |
| if ((extra = format_method_key(authctxt)) == NULL) { |
| if (authctxt->auth_method_info != NULL) |
| extra = xstrdup(authctxt->auth_method_info); |
| } |
| |
| authlog("%s %s%s%s for %s%.100s from %.200s port %d ssh2%s%s", |
| authmsg, |
| method, |
| submethod != NULL ? "/" : "", submethod == NULL ? "" : submethod, |
| authctxt->valid ? "" : "invalid user ", |
| authctxt->user, |
| ssh_remote_ipaddr(ssh), |
| ssh_remote_port(ssh), |
| extra != NULL ? ": " : "", |
| extra != NULL ? extra : ""); |
| |
| free(extra); |
| |
| #ifdef CUSTOM_FAILED_LOGIN |
| if (authenticated == 0 && !authctxt->postponed && |
| (strcmp(method, "password") == 0 || |
| strncmp(method, "keyboard-interactive", 20) == 0 || |
| strcmp(method, "challenge-response") == 0)) |
| record_failed_login(authctxt->user, |
| auth_get_canonical_hostname(ssh, options.use_dns), "ssh"); |
| # ifdef WITH_AIXAUTHENTICATE |
| if (authenticated) |
| sys_auth_record_login(authctxt->user, |
| auth_get_canonical_hostname(ssh, options.use_dns), "ssh", |
| &loginmsg); |
| # endif |
| #endif |
| #ifdef SSH_AUDIT_EVENTS |
| if (authenticated == 0 && !authctxt->postponed) |
| audit_event(audit_classify_auth(method)); |
| #endif |
| } |
| |
| |
| void |
| auth_maxtries_exceeded(Authctxt *authctxt) |
| { |
| struct ssh *ssh = active_state; /* XXX */ |
| |
| error("maximum authentication attempts exceeded for " |
| "%s%.100s from %.200s port %d ssh2", |
| authctxt->valid ? "" : "invalid user ", |
| authctxt->user, |
| ssh_remote_ipaddr(ssh), |
| ssh_remote_port(ssh)); |
| packet_disconnect("Too many authentication failures"); |
| /* NOTREACHED */ |
| } |
| |
| /* |
| * Check whether root logins are disallowed. |
| */ |
| int |
| auth_root_allowed(struct ssh *ssh, const char *method) |
| { |
| switch (options.permit_root_login) { |
| case PERMIT_YES: |
| return 1; |
| case PERMIT_NO_PASSWD: |
| if (strcmp(method, "publickey") == 0 || |
| strcmp(method, "hostbased") == 0 || |
| strcmp(method, "gssapi-with-mic") == 0) |
| return 1; |
| break; |
| case PERMIT_FORCED_ONLY: |
| if (auth_opts->force_command != NULL) { |
| logit("Root login accepted for forced command."); |
| return 1; |
| } |
| break; |
| } |
| logit("ROOT LOGIN REFUSED FROM %.200s port %d", |
| ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); |
| return 0; |
| } |
| |
| |
| /* |
| * Given a template and a passwd structure, build a filename |
| * by substituting % tokenised options. Currently, %% becomes '%', |
| * %h becomes the home directory and %u the username. |
| * |
| * This returns a buffer allocated by xmalloc. |
| */ |
| char * |
| expand_authorized_keys(const char *filename, struct passwd *pw) |
| { |
| char *file, uidstr[32], ret[PATH_MAX]; |
| int i; |
| |
| snprintf(uidstr, sizeof(uidstr), "%llu", |
| (unsigned long long)pw->pw_uid); |
| file = percent_expand(filename, "h", pw->pw_dir, |
| "u", pw->pw_name, "U", uidstr, (char *)NULL); |
| |
| /* |
| * Ensure that filename starts anchored. If not, be backward |
| * compatible and prepend the '%h/' |
| */ |
| if (*file == '/') |
| return (file); |
| |
| i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file); |
| if (i < 0 || (size_t)i >= sizeof(ret)) |
| fatal("expand_authorized_keys: path too long"); |
| free(file); |
| return (xstrdup(ret)); |
| } |
| |
| char * |
| authorized_principals_file(struct passwd *pw) |
| { |
| if (options.authorized_principals_file == NULL) |
| return NULL; |
| return expand_authorized_keys(options.authorized_principals_file, pw); |
| } |
| |
| /* return ok if key exists in sysfile or userfile */ |
| HostStatus |
| check_key_in_hostfiles(struct passwd *pw, struct sshkey *key, const char *host, |
| const char *sysfile, const char *userfile) |
| { |
| char *user_hostfile; |
| struct stat st; |
| HostStatus host_status; |
| struct hostkeys *hostkeys; |
| const struct hostkey_entry *found; |
| |
| hostkeys = init_hostkeys(); |
| load_hostkeys(hostkeys, host, sysfile); |
| if (userfile != NULL) { |
| user_hostfile = tilde_expand_filename(userfile, pw->pw_uid); |
| if (options.strict_modes && |
| (stat(user_hostfile, &st) == 0) && |
| ((st.st_uid != 0 && st.st_uid != pw->pw_uid) || |
| (st.st_mode & 022) != 0)) { |
| logit("Authentication refused for %.100s: " |
| "bad owner or modes for %.200s", |
| pw->pw_name, user_hostfile); |
| auth_debug_add("Ignored %.200s: bad ownership or modes", |
| user_hostfile); |
| } else { |
| temporarily_use_uid(pw); |
| load_hostkeys(hostkeys, host, user_hostfile); |
| restore_uid(); |
| } |
| free(user_hostfile); |
| } |
| host_status = check_key_in_hostkeys(hostkeys, key, &found); |
| if (host_status == HOST_REVOKED) |
| error("WARNING: revoked key for %s attempted authentication", |
| found->host); |
| else if (host_status == HOST_OK) |
| debug("%s: key for %s found at %s:%ld", __func__, |
| found->host, found->file, found->line); |
| else |
| debug("%s: key for host %s not found", __func__, host); |
| |
| free_hostkeys(hostkeys); |
| |
| return host_status; |
| } |
| |
| static FILE * |
| auth_openfile(const char *file, struct passwd *pw, int strict_modes, |
| int log_missing, char *file_type) |
| { |
| char line[1024]; |
| struct stat st; |
| int fd; |
| FILE *f; |
| |
| if ((fd = open(file, O_RDONLY|O_NONBLOCK)) == -1) { |
| if (log_missing || errno != ENOENT) |
| debug("Could not open %s '%s': %s", file_type, file, |
| strerror(errno)); |
| return NULL; |
| } |
| |
| if (fstat(fd, &st) < 0) { |
| close(fd); |
| return NULL; |
| } |
| if (!S_ISREG(st.st_mode)) { |
| logit("User %s %s %s is not a regular file", |
| pw->pw_name, file_type, file); |
| close(fd); |
| return NULL; |
| } |
| unset_nonblock(fd); |
| if ((f = fdopen(fd, "r")) == NULL) { |
| close(fd); |
| return NULL; |
| } |
| if (strict_modes && |
| safe_path_fd(fileno(f), file, pw, line, sizeof(line)) != 0) { |
| fclose(f); |
| logit("Authentication refused: %s", line); |
| auth_debug_add("Ignored %s: %s", file_type, line); |
| return NULL; |
| } |
| |
| return f; |
| } |
| |
| |
| FILE * |
| auth_openkeyfile(const char *file, struct passwd *pw, int strict_modes) |
| { |
| return auth_openfile(file, pw, strict_modes, 1, "authorized keys"); |
| } |
| |
| FILE * |
| auth_openprincipals(const char *file, struct passwd *pw, int strict_modes) |
| { |
| return auth_openfile(file, pw, strict_modes, 0, |
| "authorized principals"); |
| } |
| |
| struct passwd * |
| getpwnamallow(const char *user) |
| { |
| struct ssh *ssh = active_state; /* XXX */ |
| #ifdef HAVE_LOGIN_CAP |
| extern login_cap_t *lc; |
| #ifdef BSD_AUTH |
| auth_session_t *as; |
| #endif |
| #endif |
| struct passwd *pw; |
| struct connection_info *ci = get_connection_info(1, options.use_dns); |
| |
| ci->user = user; |
| parse_server_match_config(&options, ci); |
| log_change_level(options.log_level); |
| process_permitopen(ssh, &options); |
| |
| #if defined(_AIX) && defined(HAVE_SETAUTHDB) |
| aix_setauthdb(user); |
| #endif |
| |
| pw = getpwnam(user); |
| |
| #if defined(_AIX) && defined(HAVE_SETAUTHDB) |
| aix_restoreauthdb(); |
| #endif |
| #ifdef HAVE_CYGWIN |
| /* |
| * Windows usernames are case-insensitive. To avoid later problems |
| * when trying to match the username, the user is only allowed to |
| * login if the username is given in the same case as stored in the |
| * user database. |
| */ |
| if (pw != NULL && strcmp(user, pw->pw_name) != 0) { |
| logit("Login name %.100s does not match stored username %.100s", |
| user, pw->pw_name); |
| pw = NULL; |
| } |
| #endif |
| if (pw == NULL) { |
| logit("Invalid user %.100s from %.100s port %d", |
| user, ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); |
| #ifdef CUSTOM_FAILED_LOGIN |
| record_failed_login(user, |
| auth_get_canonical_hostname(ssh, options.use_dns), "ssh"); |
| #endif |
| #ifdef SSH_AUDIT_EVENTS |
| audit_event(SSH_INVALID_USER); |
| #endif /* SSH_AUDIT_EVENTS */ |
| return (NULL); |
| } |
| if (!allowed_user(pw)) |
| return (NULL); |
| #ifdef HAVE_LOGIN_CAP |
| if ((lc = login_getclass(pw->pw_class)) == NULL) { |
| debug("unable to get login class: %s", user); |
| return (NULL); |
| } |
| #ifdef BSD_AUTH |
| if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 || |
| auth_approval(as, lc, pw->pw_name, "ssh") <= 0) { |
| debug("Approval failure for %s", user); |
| pw = NULL; |
| } |
| if (as != NULL) |
| auth_close(as); |
| #endif |
| #endif |
| if (pw != NULL) |
| return (pwcopy(pw)); |
| return (NULL); |
| } |
| |
| /* Returns 1 if key is revoked by revoked_keys_file, 0 otherwise */ |
| int |
| auth_key_is_revoked(struct sshkey *key) |
| { |
| char *fp = NULL; |
| int r; |
| |
| if (options.revoked_keys_file == NULL) |
| return 0; |
| if ((fp = sshkey_fingerprint(key, options.fingerprint_hash, |
| SSH_FP_DEFAULT)) == NULL) { |
| r = SSH_ERR_ALLOC_FAIL; |
| error("%s: fingerprint key: %s", __func__, ssh_err(r)); |
| goto out; |
| } |
| |
| r = sshkey_check_revoked(key, options.revoked_keys_file); |
| switch (r) { |
| case 0: |
| break; /* not revoked */ |
| case SSH_ERR_KEY_REVOKED: |
| error("Authentication key %s %s revoked by file %s", |
| sshkey_type(key), fp, options.revoked_keys_file); |
| goto out; |
| default: |
| error("Error checking authentication key %s %s in " |
| "revoked keys file %s: %s", sshkey_type(key), fp, |
| options.revoked_keys_file, ssh_err(r)); |
| goto out; |
| } |
| |
| /* Success */ |
| r = 0; |
| |
| out: |
| free(fp); |
| return r == 0 ? 0 : 1; |
| } |
| |
| void |
| auth_debug_add(const char *fmt,...) |
| { |
| char buf[1024]; |
| va_list args; |
| |
| if (!auth_debug_init) |
| return; |
| |
| va_start(args, fmt); |
| vsnprintf(buf, sizeof(buf), fmt, args); |
| va_end(args); |
| buffer_put_cstring(&auth_debug, buf); |
| } |
| |
| void |
| auth_debug_send(void) |
| { |
| char *msg; |
| |
| if (!auth_debug_init) |
| return; |
| while (buffer_len(&auth_debug)) { |
| msg = buffer_get_string(&auth_debug, NULL); |
| packet_send_debug("%s", msg); |
| free(msg); |
| } |
| } |
| |
| void |
| auth_debug_reset(void) |
| { |
| if (auth_debug_init) |
| buffer_clear(&auth_debug); |
| else { |
| buffer_init(&auth_debug); |
| auth_debug_init = 1; |
| } |
| } |
| |
| struct passwd * |
| fakepw(void) |
| { |
| static struct passwd fake; |
| |
| memset(&fake, 0, sizeof(fake)); |
| fake.pw_name = "NOUSER"; |
| fake.pw_passwd = |
| "$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK"; |
| #ifdef HAVE_STRUCT_PASSWD_PW_GECOS |
| fake.pw_gecos = "NOUSER"; |
| #endif |
| fake.pw_uid = privsep_pw == NULL ? (uid_t)-1 : privsep_pw->pw_uid; |
| fake.pw_gid = privsep_pw == NULL ? (gid_t)-1 : privsep_pw->pw_gid; |
| #ifdef HAVE_STRUCT_PASSWD_PW_CLASS |
| fake.pw_class = ""; |
| #endif |
| fake.pw_dir = "/nonexist"; |
| fake.pw_shell = "/nonexist"; |
| |
| return (&fake); |
| } |
| |
| /* |
| * Returns the remote DNS hostname as a string. The returned string must not |
| * be freed. NB. this will usually trigger a DNS query the first time it is |
| * called. |
| * This function does additional checks on the hostname to mitigate some |
| * attacks on legacy rhosts-style authentication. |
| * XXX is RhostsRSAAuthentication vulnerable to these? |
| * XXX Can we remove these checks? (or if not, remove RhostsRSAAuthentication?) |
| */ |
| |
| static char * |
| remote_hostname(struct ssh *ssh) |
| { |
| struct sockaddr_storage from; |
| socklen_t fromlen; |
| struct addrinfo hints, *ai, *aitop; |
| char name[NI_MAXHOST], ntop2[NI_MAXHOST]; |
| const char *ntop = ssh_remote_ipaddr(ssh); |
| |
| /* Get IP address of client. */ |
| fromlen = sizeof(from); |
| memset(&from, 0, sizeof(from)); |
| if (getpeername(ssh_packet_get_connection_in(ssh), |
| (struct sockaddr *)&from, &fromlen) < 0) { |
| debug("getpeername failed: %.100s", strerror(errno)); |
| return strdup(ntop); |
| } |
| |
| ipv64_normalise_mapped(&from, &fromlen); |
| if (from.ss_family == AF_INET6) |
| fromlen = sizeof(struct sockaddr_in6); |
| |
| debug3("Trying to reverse map address %.100s.", ntop); |
| /* Map the IP address to a host name. */ |
| if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name), |
| NULL, 0, NI_NAMEREQD) != 0) { |
| /* Host name not found. Use ip address. */ |
| return strdup(ntop); |
| } |
| |
| /* |
| * if reverse lookup result looks like a numeric hostname, |
| * someone is trying to trick us by PTR record like following: |
| * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5 |
| */ |
| memset(&hints, 0, sizeof(hints)); |
| hints.ai_socktype = SOCK_DGRAM; /*dummy*/ |
| hints.ai_flags = AI_NUMERICHOST; |
| if (getaddrinfo(name, NULL, &hints, &ai) == 0) { |
| logit("Nasty PTR record \"%s\" is set up for %s, ignoring", |
| name, ntop); |
| freeaddrinfo(ai); |
| return strdup(ntop); |
| } |
| |
| /* Names are stored in lowercase. */ |
| lowercase(name); |
| |
| /* |
| * Map it back to an IP address and check that the given |
| * address actually is an address of this host. This is |
| * necessary because anyone with access to a name server can |
| * define arbitrary names for an IP address. Mapping from |
| * name to IP address can be trusted better (but can still be |
| * fooled if the intruder has access to the name server of |
| * the domain). |
| */ |
| memset(&hints, 0, sizeof(hints)); |
| hints.ai_family = from.ss_family; |
| hints.ai_socktype = SOCK_STREAM; |
| if (getaddrinfo(name, NULL, &hints, &aitop) != 0) { |
| logit("reverse mapping checking getaddrinfo for %.700s " |
| "[%s] failed.", name, ntop); |
| return strdup(ntop); |
| } |
| /* Look for the address from the list of addresses. */ |
| for (ai = aitop; ai; ai = ai->ai_next) { |
| if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2, |
| sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 && |
| (strcmp(ntop, ntop2) == 0)) |
| break; |
| } |
| freeaddrinfo(aitop); |
| /* If we reached the end of the list, the address was not there. */ |
| if (ai == NULL) { |
| /* Address not found for the host name. */ |
| logit("Address %.100s maps to %.600s, but this does not " |
| "map back to the address.", ntop, name); |
| return strdup(ntop); |
| } |
| return strdup(name); |
| } |
| |
| /* |
| * Return the canonical name of the host in the other side of the current |
| * connection. The host name is cached, so it is efficient to call this |
| * several times. |
| */ |
| |
| const char * |
| auth_get_canonical_hostname(struct ssh *ssh, int use_dns) |
| { |
| static char *dnsname; |
| |
| if (!use_dns) |
| return ssh_remote_ipaddr(ssh); |
| else if (dnsname != NULL) |
| return dnsname; |
| else { |
| dnsname = remote_hostname(ssh); |
| return dnsname; |
| } |
| } |
| |
| /* |
| * Runs command in a subprocess wuth a minimal environment. |
| * Returns pid on success, 0 on failure. |
| * The child stdout and stderr maybe captured, left attached or sent to |
| * /dev/null depending on the contents of flags. |
| * "tag" is prepended to log messages. |
| * NB. "command" is only used for logging; the actual command executed is |
| * av[0]. |
| */ |
| pid_t |
| subprocess(const char *tag, struct passwd *pw, const char *command, |
| int ac, char **av, FILE **child, u_int flags) |
| { |
| FILE *f = NULL; |
| struct stat st; |
| int fd, devnull, p[2], i; |
| pid_t pid; |
| char *cp, errmsg[512]; |
| u_int envsize; |
| char **child_env; |
| |
| if (child != NULL) |
| *child = NULL; |
| |
| debug3("%s: %s command \"%s\" running as %s (flags 0x%x)", __func__, |
| tag, command, pw->pw_name, flags); |
| |
| /* Check consistency */ |
| if ((flags & SSH_SUBPROCESS_STDOUT_DISCARD) != 0 && |
| (flags & SSH_SUBPROCESS_STDOUT_CAPTURE) != 0) { |
| error("%s: inconsistent flags", __func__); |
| return 0; |
| } |
| if (((flags & SSH_SUBPROCESS_STDOUT_CAPTURE) == 0) != (child == NULL)) { |
| error("%s: inconsistent flags/output", __func__); |
| return 0; |
| } |
| |
| /* |
| * If executing an explicit binary, then verify the it exists |
| * and appears safe-ish to execute |
| */ |
| if (*av[0] != '/') { |
| error("%s path is not absolute", tag); |
| return 0; |
| } |
| temporarily_use_uid(pw); |
| if (stat(av[0], &st) < 0) { |
| error("Could not stat %s \"%s\": %s", tag, |
| av[0], strerror(errno)); |
| restore_uid(); |
| return 0; |
| } |
| if (safe_path(av[0], &st, NULL, 0, errmsg, sizeof(errmsg)) != 0) { |
| error("Unsafe %s \"%s\": %s", tag, av[0], errmsg); |
| restore_uid(); |
| return 0; |
| } |
| /* Prepare to keep the child's stdout if requested */ |
| if (pipe(p) != 0) { |
| error("%s: pipe: %s", tag, strerror(errno)); |
| restore_uid(); |
| return 0; |
| } |
| restore_uid(); |
| |
| switch ((pid = fork())) { |
| case -1: /* error */ |
| error("%s: fork: %s", tag, strerror(errno)); |
| close(p[0]); |
| close(p[1]); |
| return 0; |
| case 0: /* child */ |
| /* Prepare a minimal environment for the child. */ |
| envsize = 5; |
| child_env = xcalloc(sizeof(*child_env), envsize); |
| child_set_env(&child_env, &envsize, "PATH", _PATH_STDPATH); |
| child_set_env(&child_env, &envsize, "USER", pw->pw_name); |
| child_set_env(&child_env, &envsize, "LOGNAME", pw->pw_name); |
| child_set_env(&child_env, &envsize, "HOME", pw->pw_dir); |
| if ((cp = getenv("LANG")) != NULL) |
| child_set_env(&child_env, &envsize, "LANG", cp); |
| |
| for (i = 0; i < NSIG; i++) |
| signal(i, SIG_DFL); |
| |
| if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) { |
| error("%s: open %s: %s", tag, _PATH_DEVNULL, |
| strerror(errno)); |
| _exit(1); |
| } |
| if (dup2(devnull, STDIN_FILENO) == -1) { |
| error("%s: dup2: %s", tag, strerror(errno)); |
| _exit(1); |
| } |
| |
| /* Set up stdout as requested; leave stderr in place for now. */ |
| fd = -1; |
| if ((flags & SSH_SUBPROCESS_STDOUT_CAPTURE) != 0) |
| fd = p[1]; |
| else if ((flags & SSH_SUBPROCESS_STDOUT_DISCARD) != 0) |
| fd = devnull; |
| if (fd != -1 && dup2(fd, STDOUT_FILENO) == -1) { |
| error("%s: dup2: %s", tag, strerror(errno)); |
| _exit(1); |
| } |
| closefrom(STDERR_FILENO + 1); |
| |
| /* Don't use permanently_set_uid() here to avoid fatal() */ |
| if (setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) != 0) { |
| error("%s: setresgid %u: %s", tag, (u_int)pw->pw_gid, |
| strerror(errno)); |
| _exit(1); |
| } |
| if (setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) != 0) { |
| error("%s: setresuid %u: %s", tag, (u_int)pw->pw_uid, |
| strerror(errno)); |
| _exit(1); |
| } |
| /* stdin is pointed to /dev/null at this point */ |
| if ((flags & SSH_SUBPROCESS_STDOUT_DISCARD) != 0 && |
| dup2(STDIN_FILENO, STDERR_FILENO) == -1) { |
| error("%s: dup2: %s", tag, strerror(errno)); |
| _exit(1); |
| } |
| |
| execve(av[0], av, child_env); |
| error("%s exec \"%s\": %s", tag, command, strerror(errno)); |
| _exit(127); |
| default: /* parent */ |
| break; |
| } |
| |
| close(p[1]); |
| if ((flags & SSH_SUBPROCESS_STDOUT_CAPTURE) == 0) |
| close(p[0]); |
| else if ((f = fdopen(p[0], "r")) == NULL) { |
| error("%s: fdopen: %s", tag, strerror(errno)); |
| close(p[0]); |
| /* Don't leave zombie child */ |
| kill(pid, SIGTERM); |
| while (waitpid(pid, NULL, 0) == -1 && errno == EINTR) |
| ; |
| return 0; |
| } |
| /* Success */ |
| debug3("%s: %s pid %ld", __func__, tag, (long)pid); |
| if (child != NULL) |
| *child = f; |
| return pid; |
| } |
| |
| /* These functions link key/cert options to the auth framework */ |
| |
| /* Log sshauthopt options locally and (optionally) for remote transmission */ |
| void |
| auth_log_authopts(const char *loc, const struct sshauthopt *opts, int do_remote) |
| { |
| int do_env = options.permit_user_env && opts->nenv > 0; |
| int do_permitopen = opts->npermitopen > 0 && |
| (options.allow_tcp_forwarding & FORWARD_LOCAL) != 0; |
| size_t i; |
| char msg[1024], buf[64]; |
| |
| snprintf(buf, sizeof(buf), "%d", opts->force_tun_device); |
| /* Try to keep this alphabetically sorted */ |
| snprintf(msg, sizeof(msg), "key options:%s%s%s%s%s%s%s%s%s%s%s%s", |
| opts->permit_agent_forwarding_flag ? " agent-forwarding" : "", |
| opts->force_command == NULL ? "" : " command", |
| do_env ? " environment" : "", |
| opts->valid_before == 0 ? "" : "expires", |
| do_permitopen ? " permitopen" : "", |
| opts->permit_port_forwarding_flag ? " port-forwarding" : "", |
| opts->cert_principals == NULL ? "" : " principals", |
| opts->permit_pty_flag ? " pty" : "", |
| opts->force_tun_device == -1 ? "" : " tun=", |
| opts->force_tun_device == -1 ? "" : buf, |
| opts->permit_user_rc ? " user-rc" : "", |
| opts->permit_x11_forwarding_flag ? " x11-forwarding" : ""); |
| |
| debug("%s: %s", loc, msg); |
| if (do_remote) |
| auth_debug_add("%s: %s", loc, msg); |
| |
| if (options.permit_user_env) { |
| for (i = 0; i < opts->nenv; i++) { |
| debug("%s: environment: %s", loc, opts->env[i]); |
| if (do_remote) { |
| auth_debug_add("%s: environment: %s", |
| loc, opts->env[i]); |
| } |
| } |
| } |
| |
| /* Go into a little more details for the local logs. */ |
| if (opts->valid_before != 0) { |
| format_absolute_time(opts->valid_before, buf, sizeof(buf)); |
| debug("%s: expires at %s", loc, buf); |
| } |
| if (opts->cert_principals != NULL) { |
| debug("%s: authorized principals: \"%s\"", |
| loc, opts->cert_principals); |
| } |
| if (opts->force_command != NULL) |
| debug("%s: forced command: \"%s\"", loc, opts->force_command); |
| if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0) { |
| for (i = 0; i < opts->npermitopen; i++) { |
| debug("%s: permitted open: %s", |
| loc, opts->permitopen[i]); |
| } |
| } |
| } |
| |
| /* Activate a new set of key/cert options; merging with what is there. */ |
| int |
| auth_activate_options(struct ssh *ssh, struct sshauthopt *opts) |
| { |
| struct sshauthopt *old = auth_opts; |
| const char *emsg = NULL; |
| |
| debug("%s: setting new authentication options", __func__); |
| if ((auth_opts = sshauthopt_merge(old, opts, &emsg)) == NULL) { |
| error("Inconsistent authentication options: %s", emsg); |
| return -1; |
| } |
| return 0; |
| } |
| |
| /* Disable forwarding, etc for the session */ |
| void |
| auth_restrict_session(struct ssh *ssh) |
| { |
| struct sshauthopt *restricted; |
| |
| debug("%s: restricting session", __func__); |
| |
| /* A blank sshauthopt defaults to permitting nothing */ |
| restricted = sshauthopt_new(); |
| restricted->permit_pty_flag = 1; |
| restricted->restricted = 1; |
| |
| if (auth_activate_options(ssh, restricted) != 0) |
| fatal("%s: failed to restrict session", __func__); |
| sshauthopt_free(restricted); |
| } |
| |
| int |
| auth_authorise_keyopts(struct ssh *ssh, struct passwd *pw, |
| struct sshauthopt *opts, int allow_cert_authority, const char *loc) |
| { |
| const char *remote_ip = ssh_remote_ipaddr(ssh); |
| const char *remote_host = auth_get_canonical_hostname(ssh, |
| options.use_dns); |
| time_t now = time(NULL); |
| char buf[64]; |
| |
| /* |
| * Check keys/principals file expiry time. |
| * NB. validity interval in certificate is handled elsewhere. |
| */ |
| if (opts->valid_before && now > 0 && |
| opts->valid_before < (uint64_t)now) { |
| format_absolute_time(opts->valid_before, buf, sizeof(buf)); |
| debug("%s: entry expired at %s", loc, buf); |
| auth_debug_add("%s: entry expired at %s", loc, buf); |
| return -1; |
| } |
| /* Consistency checks */ |
| if (opts->cert_principals != NULL && !opts->cert_authority) { |
| debug("%s: principals on non-CA key", loc); |
| auth_debug_add("%s: principals on non-CA key", loc); |
| /* deny access */ |
| return -1; |
| } |
| /* cert-authority flag isn't valid in authorized_principals files */ |
| if (!allow_cert_authority && opts->cert_authority) { |
| debug("%s: cert-authority flag invalid here", loc); |
| auth_debug_add("%s: cert-authority flag invalid here", loc); |
| /* deny access */ |
| return -1; |
| } |
| |
| /* Perform from= checks */ |
| if (opts->required_from_host_keys != NULL) { |
| switch (match_host_and_ip(remote_host, remote_ip, |
| opts->required_from_host_keys )) { |
| case 1: |
| /* Host name matches. */ |
| break; |
| case -1: |
| default: |
| debug("%s: invalid from criteria", loc); |
| auth_debug_add("%s: invalid from criteria", loc); |
| /* FALLTHROUGH */ |
| case 0: |
| logit("%s: Authentication tried for %.100s with " |
| "correct key but not from a permitted " |
| "host (host=%.200s, ip=%.200s, required=%.200s).", |
| loc, pw->pw_name, remote_host, remote_ip, |
| opts->required_from_host_keys); |
| auth_debug_add("%s: Your host '%.200s' is not " |
| "permitted to use this key for login.", |
| loc, remote_host); |
| /* deny access */ |
| return -1; |
| } |
| } |
| /* Check source-address restriction from certificate */ |
| if (opts->required_from_host_cert != NULL) { |
| switch (addr_match_cidr_list(remote_ip, |
| opts->required_from_host_cert)) { |
| case 1: |
| /* accepted */ |
| break; |
| case -1: |
| default: |
| /* invalid */ |
| error("%s: Certificate source-address invalid", |
| loc); |
| /* FALLTHROUGH */ |
| case 0: |
| logit("%s: Authentication tried for %.100s with valid " |
| "certificate but not from a permitted source " |
| "address (%.200s).", loc, pw->pw_name, remote_ip); |
| auth_debug_add("%s: Your address '%.200s' is not " |
| "permitted to use this certificate for login.", |
| loc, remote_ip); |
| return -1; |
| } |
| } |
| /* |
| * |
| * XXX this is spammy. We should report remotely only for keys |
| * that are successful in actual auth attempts, and not PK_OK |
| * tests. |
| */ |
| auth_log_authopts(loc, opts, 1); |
| |
| return 0; |
| } |