X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/c345cf9d1095299a9077386c1188a86090d385a9..1836f69f0538fd8f9ecdad854e2fd6ed9990546f:/auth.c diff --git a/auth.c b/auth.c index dc3e8211..62c184dd 100644 --- a/auth.c +++ b/auth.c @@ -1,24 +1,30 @@ /* - * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland - * All rights reserved - * Copyright (c) 2000 Markus Friedl. All rights reserved. + * Copyright (c) 2000 Markus Friedl. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #include "includes.h" -RCSID("$OpenBSD: auth.c,v 1.8 2000/08/04 20:30:07 markus Exp $"); +RCSID("$OpenBSD: auth.c,v 1.38 2002/03/18 03:41:08 provos Exp $"); -#include "xmalloc.h" -#include "rsa.h" -#include "ssh.h" -#include "pty.h" -#include "packet.h" -#include "buffer.h" -#include "cipher.h" -#include "mpaux.h" -#include "servconf.h" -#include "compat.h" -#include "channels.h" -#include "match.h" #ifdef HAVE_LOGIN_H #include #endif @@ -26,21 +32,32 @@ RCSID("$OpenBSD: auth.c,v 1.8 2000/08/04 20:30:07 markus Exp $"); #include #endif /* defined(HAVE_SHADOW_H) && !defined(DISABLE_SHADOW) */ -#include "bufaux.h" -#include "ssh2.h" +#ifdef HAVE_LIBGEN_H +#include +#endif + +#include "xmalloc.h" +#include "match.h" +#include "groupaccess.h" +#include "log.h" +#include "servconf.h" #include "auth.h" -#include "session.h" +#include "auth-options.h" +#include "canohost.h" +#include "buffer.h" +#include "bufaux.h" +#include "uidswap.h" +#include "tildexpand.h" /* import */ extern ServerOptions options; -extern char *forced_command; /* - * Check if the user is allowed to log in via ssh. If user is listed in - * DenyUsers or user's primary group 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 user isn't listed there, false will be - * returned. + * 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. */ @@ -48,18 +65,18 @@ int allowed_user(struct passwd * pw) { struct stat st; - struct group *grp; + const char *hostname = NULL, *ipaddr = NULL; char *shell; int i; #ifdef WITH_AIXAUTHENTICATE char *loginmsg; #endif /* WITH_AIXAUTHENTICATE */ -#if defined(HAVE_SHADOW_H) && !defined(DISABLE_SHADOW) && \ - defined(HAS_SHADOW_EXPIRE) - struct spwd *spw; +#if !defined(USE_PAM) && defined(HAVE_SHADOW_H) && \ + !defined(DISABLE_SHADOW) && defined(HAS_SHADOW_EXPIRE) + struct spwd *spw; /* Shouldn't be called if pw is NULL, but better safe than sorry... */ - if (!pw) + if (!pw || !pw->pw_name) return 0; spw = getspnam(pw->pw_name); @@ -67,17 +84,17 @@ allowed_user(struct passwd * pw) int days = time(NULL) / 86400; /* Check account expiry */ - if ((spw->sp_expire > 0) && (days > spw->sp_expire)) + if ((spw->sp_expire >= 0) && (days > spw->sp_expire)) return 0; /* Check password expiry */ - if ((spw->sp_lstchg > 0) && (spw->sp_inact > 0) && - (days > (spw->sp_lstchg + spw->sp_inact))) + if ((spw->sp_lstchg >= 0) && (spw->sp_max >= 0) && + (days > (spw->sp_lstchg + spw->sp_max))) return 0; } #else /* Shouldn't be called if pw is NULL, but better safe than sorry... */ - if (!pw) + if (!pw || !pw->pw_name) return 0; #endif @@ -88,59 +105,76 @@ allowed_user(struct passwd * pw) shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; /* deny if shell does not exists or is not executable */ - if (stat(shell, &st) != 0) + if (stat(shell, &st) != 0) { + log("User %.100s not allowed because shell %.100s does not exist", + pw->pw_name, shell); return 0; - if (!((st.st_mode & S_IFREG) && (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)))) + } + if (S_ISREG(st.st_mode) == 0 || + (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) { + log("User %.100s not allowed because shell %.100s is not executable", + pw->pw_name, shell); return 0; + } + + if (options.num_deny_users > 0 || options.num_allow_users > 0) { + hostname = get_canonical_hostname(options.verify_reverse_mapping); + ipaddr = get_remote_ipaddr(); + } /* Return false if user is listed in DenyUsers */ if (options.num_deny_users > 0) { - if (!pw->pw_name) - return 0; for (i = 0; i < options.num_deny_users; i++) - if (match_pattern(pw->pw_name, options.deny_users[i])) + if (match_user(pw->pw_name, hostname, ipaddr, + options.deny_users[i])) { + log("User %.100s not allowed because listed in DenyUsers", + pw->pw_name); return 0; + } } /* Return false if AllowUsers isn't empty and user isn't listed there */ if (options.num_allow_users > 0) { - if (!pw->pw_name) - return 0; for (i = 0; i < options.num_allow_users; i++) - if (match_pattern(pw->pw_name, options.allow_users[i])) + if (match_user(pw->pw_name, hostname, ipaddr, + options.allow_users[i])) break; /* i < options.num_allow_users iff we break for loop */ - if (i >= options.num_allow_users) + if (i >= options.num_allow_users) { + log("User %.100s not allowed because not listed in AllowUsers", + pw->pw_name); return 0; + } } - /* Get the primary group name if we need it. Return false if it fails */ if (options.num_deny_groups > 0 || options.num_allow_groups > 0) { - grp = getgrgid(pw->pw_gid); - if (!grp) + /* Get the user's group access list (primary and supplementary) */ + if (ga_init(pw->pw_name, pw->pw_gid) == 0) { + log("User %.100s not allowed because not in any group", + pw->pw_name); return 0; + } - /* Return false if user's group is listed in DenyGroups */ - if (options.num_deny_groups > 0) { - if (!grp->gr_name) + /* 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(); + log("User %.100s not allowed because a group is listed in DenyGroups", + pw->pw_name); return 0; - for (i = 0; i < options.num_deny_groups; i++) - if (match_pattern(grp->gr_name, options.deny_groups[i])) - return 0; - } + } /* - * Return false if AllowGroups isn't empty and user's group + * Return false if AllowGroups isn't empty and one of user's groups * isn't listed there */ - if (options.num_allow_groups > 0) { - if (!grp->gr_name) - return 0; - for (i = 0; i < options.num_allow_groups; i++) - if (match_pattern(grp->gr_name, options.allow_groups[i])) - break; - /* i < options.num_allow_groups iff we break for - loop */ - if (i >= options.num_allow_groups) + if (options.num_allow_groups > 0) + if (!ga_match(options.allow_groups, + options.num_allow_groups)) { + ga_free(); + log("User %.100s not allowed because none of user's groups are listed in AllowGroups", + pw->pw_name); return 0; - } + } + ga_free(); } #ifdef WITH_AIXAUTHENTICATE @@ -163,3 +197,277 @@ allowed_user(struct passwd * pw) /* We found no reason not to let this user try to log on... */ return 1; } + +Authctxt * +authctxt_new(void) +{ + Authctxt *authctxt = xmalloc(sizeof(*authctxt)); + memset(authctxt, 0, sizeof(*authctxt)); + return authctxt; +} + +void +auth_log(Authctxt *authctxt, int authenticated, char *method, char *info) +{ + void (*authlog) (const char *fmt,...) = verbose; + char *authmsg; + + /* Raise logging level */ + if (authenticated == 1 || + !authctxt->valid || + authctxt->failures >= AUTH_FAIL_LOG || + strcmp(method, "password") == 0) + authlog = log; + + if (authctxt->postponed) + authmsg = "Postponed"; + else + authmsg = authenticated ? "Accepted" : "Failed"; + + authlog("%s %s for %s%.100s from %.200s port %d%s", + authmsg, + method, + authctxt->valid ? "" : "illegal user ", + authctxt->user, + get_remote_ipaddr(), + get_remote_port(), + info); +} + +/* + * Check whether root logins are disallowed. + */ +int +auth_root_allowed(char *method) +{ + switch (options.permit_root_login) { + case PERMIT_YES: + return 1; + break; + case PERMIT_NO_PASSWD: + if (strcmp(method, "password") != 0) + return 1; + break; + case PERMIT_FORCED_ONLY: + if (forced_command) { + log("Root login accepted for forced command."); + return 1; + } + break; + } + log("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr()); + 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_filename(const char *filename, struct passwd *pw) +{ + Buffer buffer; + char *file; + const char *cp; + + /* + * Build the filename string in the buffer by making the appropriate + * substitutions to the given file name. + */ + buffer_init(&buffer); + for (cp = filename; *cp; cp++) { + if (cp[0] == '%' && cp[1] == '%') { + buffer_append(&buffer, "%", 1); + cp++; + continue; + } + if (cp[0] == '%' && cp[1] == 'h') { + buffer_append(&buffer, pw->pw_dir, strlen(pw->pw_dir)); + cp++; + continue; + } + if (cp[0] == '%' && cp[1] == 'u') { + buffer_append(&buffer, pw->pw_name, + strlen(pw->pw_name)); + cp++; + continue; + } + buffer_append(&buffer, cp, 1); + } + buffer_append(&buffer, "\0", 1); + + /* + * Ensure that filename starts anchored. If not, be backward + * compatible and prepend the '%h/' + */ + file = xmalloc(MAXPATHLEN); + cp = buffer_ptr(&buffer); + if (*cp != '/') + snprintf(file, MAXPATHLEN, "%s/%s", pw->pw_dir, cp); + else + strlcpy(file, cp, MAXPATHLEN); + + buffer_free(&buffer); + return file; +} + +char * +authorized_keys_file(struct passwd *pw) +{ + return expand_filename(options.authorized_keys_file, pw); +} + +char * +authorized_keys_file2(struct passwd *pw) +{ + return expand_filename(options.authorized_keys_file2, pw); +} + +/* return ok if key exists in sysfile or userfile */ +HostStatus +check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host, + const char *sysfile, const char *userfile) +{ + Key *found; + char *user_hostfile; + struct stat st; + HostStatus host_status; + + /* Check if we know the host and its host key. */ + found = key_new(key->type); + host_status = check_host_in_hostfile(sysfile, host, key, found, NULL); + + if (host_status != HOST_OK && 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)) { + log("Authentication refused for %.100s: " + "bad owner or modes for %.200s", + pw->pw_name, user_hostfile); + } else { + temporarily_use_uid(pw); + host_status = check_host_in_hostfile(user_hostfile, + host, key, found, NULL); + restore_uid(); + } + xfree(user_hostfile); + } + key_free(found); + + debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ? + "ok" : "not found", host); + return host_status; +} + + +/* + * Check a given file for security. This is defined as all components + * of the path to the file must either be owned by either the owner of + * of the file or root and no directories must be group or world writable. + * + * XXX Should any specific check be done for sym links ? + * + * Takes an open file descriptor, the file name, a uid and and + * error buffer plus max size as arguments. + * + * Returns 0 on success and -1 on failure + */ +int +secure_filename(FILE *f, const char *file, struct passwd *pw, + char *err, size_t errlen) +{ + uid_t uid = pw->pw_uid; + char buf[MAXPATHLEN], homedir[MAXPATHLEN]; + char *cp; + struct stat st; + + if (realpath(file, buf) == NULL) { + snprintf(err, errlen, "realpath %s failed: %s", file, + strerror(errno)); + return -1; + } + if (realpath(pw->pw_dir, homedir) == NULL) { + snprintf(err, errlen, "realpath %s failed: %s", pw->pw_dir, + strerror(errno)); + return -1; + } + + /* check the open file to avoid races */ + if (fstat(fileno(f), &st) < 0 || + (st.st_uid != 0 && st.st_uid != uid) || + (st.st_mode & 022) != 0) { + snprintf(err, errlen, "bad ownership or modes for file %s", + buf); + return -1; + } + + /* for each component of the canonical path, walking upwards */ + for (;;) { + if ((cp = dirname(buf)) == NULL) { + snprintf(err, errlen, "dirname() failed"); + return -1; + } + strlcpy(buf, cp, sizeof(buf)); + + debug3("secure_filename: checking '%s'", buf); + if (stat(buf, &st) < 0 || + (st.st_uid != 0 && st.st_uid != uid) || + (st.st_mode & 022) != 0) { + snprintf(err, errlen, + "bad ownership or modes for directory %s", buf); + return -1; + } + + /* If are passed the homedir then we can stop */ + if (strcmp(homedir, buf) == 0) { + debug3("secure_filename: terminating check at '%s'", + buf); + break; + } + /* + * dirname should always complete with a "/" path, + * but we can be paranoid and check for "." too + */ + if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0)) + break; + } + return 0; +} + +struct passwd * +getpwnamallow(const char *user) +{ +#ifdef HAVE_LOGIN_CAP + extern login_cap_t *lc; +#ifdef BSD_AUTH + auth_session_t *as; +#endif +#endif + struct passwd *pw; + + pw = getpwnam(user); + if (pw == NULL || !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(NULL, lc, pw->pw_name, "ssh") <= 0) { + debug("Approval failure for %s", user); + pw = NULL; + } + if (as != NULL) + auth_close(as); +#endif +#endif + return (pw); +}