X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/59c9718951e2de053174eaa7df6ecc74642d03a4..f666dcfa41a9a4bebf8dec0b667efae446908e8a:/auth.c diff --git a/auth.c b/auth.c index 814506d7..2dc5c2be 100644 --- a/auth.c +++ b/auth.c @@ -1,5 +1,5 @@ /* - * 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 @@ -23,25 +23,43 @@ */ #include "includes.h" -RCSID("$OpenBSD: auth.c,v 1.13 2001/01/18 16:59:59 markus Exp $"); +RCSID("$OpenBSD: auth.c,v 1.60 2005/06/17 02:44:32 djm Exp $"); -#include "xmalloc.h" -#include "ssh.h" -#include "match.h" -#include "servconf.h" -#include "groupaccess.h" #ifdef HAVE_LOGIN_H #include #endif -#if defined(HAVE_SHADOW_H) && !defined(DISABLE_SHADOW) +#ifdef USE_SHADOW #include -#endif /* defined(HAVE_SHADOW_H) && !defined(DISABLE_SHADOW) */ +#endif +#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 "auth-options.h" +#include "canohost.h" +#include "buffer.h" +#include "bufaux.h" +#include "uidswap.h" +#include "misc.h" +#include "bufaux.h" +#include "packet.h" +#include "loginrec.h" +#include "monitor_wrap.h" /* import */ extern ServerOptions options; +extern Buffer loginmsg; + +/* Debugging messages */ +Buffer auth_debug; +int auth_debug_init; /* * Check if the user is allowed to log in via ssh. If user is listed @@ -56,37 +74,64 @@ int allowed_user(struct passwd * pw) { struct stat st; + const char *hostname = NULL, *ipaddr = NULL, *passwd = NULL; char *shell; - int i; -#ifdef WITH_AIXAUTHENTICATE - char *loginmsg; -#endif /* WITH_AIXAUTHENTICATE */ -#if !defined(USE_PAM) && defined(HAVE_SHADOW_H) && \ - !defined(DISABLE_SHADOW) && defined(HAS_SHADOW_EXPIRE) - struct spwd *spw; + u_int i; +#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; - spw = getspnam(pw->pw_name); - if (spw != NULL) { - int days = time(NULL) / 86400; +#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 */ - /* Check account expiry */ - if ((spw->sp_expire >= 0) && (days > spw->sp_expire)) - return 0; + /* grab passwd field for locked account check */ +#ifdef USE_SHADOW + if (spw != NULL) +#if defined(HAVE_LIBIAF) && !defined(BROKEN_LIBIAF) + passwd = get_iaf_password(pw); +#else + passwd = spw->sp_pwdp; +#endif /* HAVE_LIBIAF && !BROKEN_LIBIAF */ +#else + passwd = pw->pw_passwd; +#endif + + /* check for locked account */ + if (!options.use_pam && passwd && *passwd) { + int locked = 0; - /* Check password expiry */ - if ((spw->sp_lstchg >= 0) && (spw->sp_max >= 0) && - (days > (spw->sp_lstchg + spw->sp_max))) +#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 +#if defined(HAVE_LIBIAF) && !defined(BROKEN_LIBIAF) + free(passwd); +#endif /* HAVE_LIBIAF && !BROKEN_LIBIAF */ + if (locked) { + logit("User %.100s not allowed because account is locked", + pw->pw_name); return 0; + } } -#else - /* Shouldn't be called if pw is NULL, but better safe than sorry... */ - if (!pw || !pw->pw_name) - return 0; -#endif /* * Get the shell from the password data. An empty shell field is @@ -95,36 +140,64 @@ 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) { + logit("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) { + logit("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 || + options.num_deny_groups > 0 || options.num_allow_groups > 0) { + hostname = get_canonical_hostname(options.use_dns); + ipaddr = get_remote_ipaddr(); + } /* Return false if user is listed in DenyUsers */ if (options.num_deny_users > 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])) { + 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++) - 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) { + 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) + 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; } /* @@ -135,57 +208,23 @@ allowed_user(struct passwd * pw) 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 WITH_AIXAUTHENTICATE - if (loginrestrictions(pw->pw_name, S_RLOGIN, NULL, &loginmsg) != 0) { - if (loginmsg && *loginmsg) { - /* Remove embedded newlines (if any) */ - char *p; - for (p = loginmsg; *p; p++) { - if (*p == '\n') - *p = ' '; - } - /* Remove trailing newline */ - *--p = '\0'; - log("Login restricted for %s: %.100s", pw->pw_name, loginmsg); - } +#ifdef CUSTOM_SYS_AUTH_ALLOWED_USER + if (!sys_auth_allowed_user(pw, &loginmsg)) return 0; - } -#endif /* WITH_AIXAUTHENTICATE */ +#endif /* 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; -} - -struct passwd * -pwcopy(struct passwd *pw) -{ - struct passwd *copy = xmalloc(sizeof(*copy)); - memset(copy, 0, sizeof(*copy)); - copy->pw_name = xstrdup(pw->pw_name); - copy->pw_passwd = xstrdup(pw->pw_passwd); - copy->pw_uid = pw->pw_uid; - copy->pw_gid = pw->pw_gid; -#ifdef HAVE_PW_CLASS_IN_PASSWD - copy->pw_class = xstrdup(pw->pw_class); -#endif - copy->pw_dir = xstrdup(pw->pw_dir); - copy->pw_shell = xstrdup(pw->pw_shell); - return copy; -} - void auth_log(Authctxt *authctxt, int authenticated, char *method, char *info) { @@ -195,9 +234,9 @@ auth_log(Authctxt *authctxt, int authenticated, char *method, char *info) /* Raise logging level */ if (authenticated == 1 || !authctxt->valid || - authctxt->failures >= AUTH_FAIL_LOG || + authctxt->failures >= options.max_authtries / 2 || strcmp(method, "password") == 0) - authlog = log; + authlog = logit; if (authctxt->postponed) authmsg = "Postponed"; @@ -207,27 +246,344 @@ auth_log(Authctxt *authctxt, int authenticated, char *method, char *info) authlog("%s %s for %s%.100s from %.200s port %d%s", authmsg, method, - authctxt->valid ? "" : "illegal user ", - authctxt->valid && authctxt->pw->pw_uid == 0 ? "ROOT" : authctxt->user, + authctxt->valid ? "" : "invalid user ", + authctxt->user, get_remote_ipaddr(), get_remote_port(), info); + +#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, + get_canonical_hostname(options.use_dns), "ssh"); +#endif +#ifdef SSH_AUDIT_EVENTS + if (authenticated == 0 && !authctxt->postponed) { + ssh_audit_event_t event; + + debug3("audit failed auth attempt, method %s euid %d", + method, (int)geteuid()); + /* + * Because the auth loop is used in both monitor and slave, + * we must be careful to send each event only once and with + * enough privs to write the event. + */ + event = audit_classify_auth(method); + switch(event) { + case SSH_AUTH_FAIL_NONE: + case SSH_AUTH_FAIL_PASSWD: + case SSH_AUTH_FAIL_KBDINT: + if (geteuid() == 0) + audit_event(event); + break; + case SSH_AUTH_FAIL_PUBKEY: + case SSH_AUTH_FAIL_HOSTBASED: + case SSH_AUTH_FAIL_GSSAPI: + /* + * This is required to handle the case where privsep + * is enabled but it's root logging in, since + * use_privsep won't be cleared until after a + * successful login. + */ + if (geteuid() == 0) + audit_event(event); + else + PRIVSEP(audit_event(event)); + break; + default: + error("unknown authentication audit event %d", event); + } + } +#endif } /* - * Check if the user is logging in as root and root logins are disallowed. - * Note that root login is _allways_ allowed for forced commands. + * Check whether root logins are disallowed. */ int -auth_root_allowed(void) +auth_root_allowed(char *method) { - if (options.permit_root_login) - return 1; - if (forced_command) { - log("Root login accepted for forced command."); + switch (options.permit_root_login) { + case PERMIT_YES: return 1; - } else { - log("ROOT LOGIN REFUSED FROM %.200s", get_canonical_hostname()); - return 0; + break; + case PERMIT_NO_PASSWD: + if (strcmp(method, "password") != 0) + return 1; + break; + case PERMIT_FORCED_ONLY: + if (forced_command) { + logit("Root login accepted for forced command."); + return 1; + } + break; } + logit("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. + */ +static char * +expand_authorized_keys(const char *filename, struct passwd *pw) +{ + char *file, *ret; + + file = percent_expand(filename, "h", pw->pw_dir, + "u", pw->pw_name, (char *)NULL); + + /* + * Ensure that filename starts anchored. If not, be backward + * compatible and prepend the '%h/' + */ + if (*file == '/') + return (file); + + ret = xmalloc(MAXPATHLEN); + if (strlcpy(ret, pw->pw_dir, MAXPATHLEN) >= MAXPATHLEN || + strlcat(ret, "/", MAXPATHLEN) >= MAXPATHLEN || + strlcat(ret, file, MAXPATHLEN) >= MAXPATHLEN) + fatal("expand_authorized_keys: path too long"); + + xfree(file); + return (ret); +} + +char * +authorized_keys_file(struct passwd *pw) +{ + return expand_authorized_keys(options.authorized_keys_file, pw); +} + +char * +authorized_keys_file2(struct passwd *pw) +{ + return expand_authorized_keys(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)) { + logit("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 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; + int comparehome = 0; + 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) + comparehome = 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 (comparehome && 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) { + logit("Invalid user %.100s from %.100s", + user, get_remote_ipaddr()); +#ifdef CUSTOM_FAILED_LOGIN + record_failed_login(user, + get_canonical_hostname(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); +} + +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); + xfree(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"; + fake.pw_gecos = "NOUSER"; + fake.pw_uid = (uid_t)-1; + fake.pw_gid = (gid_t)-1; +#ifdef HAVE_PW_CLASS_IN_PASSWD + fake.pw_class = ""; +#endif + fake.pw_dir = "/nonexist"; + fake.pw_shell = "/nonexist"; + + return (&fake); }