-/*
- * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
- * All rights reserved
+r/*
+ * 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 1.1 2000/03/28 21:15:45 markus Exp $");
+RCSID("$OpenBSD: auth.c,v 1.43 2002/05/17 14:27:55 millert Exp $");
+
+#ifdef HAVE_LOGIN_H
+#include <login.h>
+#endif
+#if defined(HAVE_SHADOW_H) && !defined(DISABLE_SHADOW)
+#include <shadow.h>
+#endif /* defined(HAVE_SHADOW_H) && !defined(DISABLE_SHADOW) */
+
+#ifdef HAVE_LIBGEN_H
+#include <libgen.h>
+#endif
#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 "channels.h"
#include "match.h"
-
-#include "session.h"
-#include "dispatch.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 "tildexpand.h"
+#include "misc.h"
+#include "bufaux.h"
+#include "packet.h"
/* import */
extern ServerOptions options;
-extern char *forced_command;
+
+/* 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 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.
+ * Otherwise true is returned.
*/
-static int
+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(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;
+#define DAY (24L * 60 * 60) /* 1 day in seconds */
+ spw = getspnam(pw->pw_name);
+ if (spw != NULL) {
+ time_t today = time(NULL) / DAY;
+ debug3("allowed_user: today %d sp_expire %d sp_lstchg %d"
+ " sp_max %d", (int)today, (int)spw->sp_expire,
+ (int)spw->sp_lstchg, (int)spw->sp_max);
+
+ /*
+ * We assume account and password expiration occurs the
+ * day after the day specified.
+ */
+ if (spw->sp_expire != -1 && today > spw->sp_expire) {
+ log("Account %.100s has expired", pw->pw_name);
+ return 0;
+ }
+
+ if (spw->sp_lstchg == 0) {
+ log("User %.100s password has expired (root forced)",
+ pw->pw_name);
+ return 0;
+ }
+
+ if (spw->sp_max != -1 &&
+ today > spw->sp_lstchg + spw->sp_max) {
+ log("User %.100s password has expired (password aged)",
+ 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
+ * legal, and means /bin/sh.
+ */
+ shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
+
/* deny if shell does not exists or is not executable */
- if (stat(pw->pw_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
- if (loginrestrictions(pw->pw_name,S_LOGIN,NULL,&loginmsg) != 0)
+ 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);
+ }
return 0;
+ }
#endif /* WITH_AIXAUTHENTICATE */
/* 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);
+}
+
/*
- * convert ssh auth msg type into description
+ * Check whether root logins are disallowed.
*/
-char *
-get_authname(int type)
+int
+auth_root_allowed(char *method)
{
- static char buf[1024];
- switch (type) {
- case SSH_CMSG_AUTH_PASSWORD:
- return "password";
- case SSH_CMSG_AUTH_RSA:
- return "rsa";
- case SSH_CMSG_AUTH_RHOSTS_RSA:
- return "rhosts-rsa";
- case SSH_CMSG_AUTH_RHOSTS:
- return "rhosts";
-#ifdef KRB4
- case SSH_CMSG_AUTH_KERBEROS:
- return "kerberos";
-#endif
-#ifdef SKEY
- case SSH_CMSG_AUTH_TIS_RESPONSE:
- return "s/key";
-#endif
+ 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;
}
- snprintf(buf, sizeof buf, "bad-auth-msg-%d", type);
- return buf;
+ log("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
+ return 0;
}
-#define AUTH_FAIL_MAX 6
-#define AUTH_FAIL_LOG (AUTH_FAIL_MAX/2)
-#define AUTH_FAIL_MSG "Too many authentication failures for %.100s"
/*
- * The user does not exist or access is denied,
- * but fake indication that authentication is needed.
+ * 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.
*/
-void
-do_fake_authloop1(char *user)
+char *
+expand_filename(const char *filename, struct passwd *pw)
{
- int attempt = 0;
-
- log("Faking authloop for illegal user %.200s from %.200s port %d",
- user,
- get_remote_ipaddr(),
- get_remote_port());
-
-#ifdef WITH_AIXAUTHENTICATE
- if (strncmp(get_authname(type),"password",
- strlen(get_authname(type))) == 0)
- loginfailed(pw->pw_name,get_canonical_hostname(),"ssh");
-#endif /* WITH_AIXAUTHENTICATE */
-
- /* Indicate that authentication is needed. */
- packet_start(SSH_SMSG_FAILURE);
- packet_send();
- packet_write_wait();
+ Buffer buffer;
+ char *file;
+ const char *cp;
/*
- * Keep reading packets, and always respond with a failure. This is
- * to avoid disclosing whether such a user really exists.
+ * Build the filename string in the buffer by making the appropriate
+ * substitutions to the given file name.
*/
- for (attempt = 1;; attempt++) {
- /* Read a packet. This will not return if the client disconnects. */
- int plen;
-#ifndef SKEY
- (void)packet_read(&plen);
-#else /* SKEY */
- int type = packet_read(&plen);
- unsigned int dlen;
- char *password, *skeyinfo;
- /* Try to send a fake s/key challenge. */
- if (options.skey_authentication == 1 &&
- (skeyinfo = skey_fake_keyinfo(user)) != NULL) {
- password = NULL;
- if (type == SSH_CMSG_AUTH_TIS) {
- packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE);
- packet_put_string(skeyinfo, strlen(skeyinfo));
- packet_send();
- packet_write_wait();
- continue;
- } else if (type == SSH_CMSG_AUTH_PASSWORD &&
- options.password_authentication &&
- (password = packet_get_string(&dlen)) != NULL &&
- dlen == 5 &&
- strncasecmp(password, "s/key", 5) == 0 ) {
- packet_send_debug(skeyinfo);
- }
- if (password != NULL)
- xfree(password);
+ buffer_init(&buffer);
+ for (cp = filename; *cp; cp++) {
+ if (cp[0] == '%' && cp[1] == '%') {
+ buffer_append(&buffer, "%", 1);
+ cp++;
+ continue;
}
-#endif
- if (attempt > AUTH_FAIL_MAX)
- packet_disconnect(AUTH_FAIL_MSG, user);
-
- /*
- * Send failure. This should be indistinguishable from a
- * failed authentication.
- */
- packet_start(SSH_SMSG_FAILURE);
- packet_send();
- packet_write_wait();
+ 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);
}
- /* NOTREACHED */
- abort();
+ 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;
}
-/*
- * read packets and try to authenticate local user *pw.
- * return if authentication is successfull
- */
-void
-do_authloop(struct passwd * pw)
+char *
+authorized_keys_file(struct passwd *pw)
{
- int attempt = 0;
- unsigned int bits;
- RSA *client_host_key;
- BIGNUM *n;
- char *client_user = NULL, *password = NULL;
- char user[1024];
- unsigned int dlen;
- int plen, nlen, elen;
- unsigned int ulen;
- int type = 0;
- void (*authlog) (const char *fmt,...) = verbose;
-
- /* Indicate that authentication is needed. */
- packet_start(SSH_SMSG_FAILURE);
- packet_send();
- packet_write_wait();
-
- for (attempt = 1;; attempt++) {
- int authenticated = 0;
- strlcpy(user, "", sizeof user);
-
- /* Get a packet from the client. */
- type = packet_read(&plen);
-
- /* Process the packet. */
- switch (type) {
-#ifdef AFS
- case SSH_CMSG_HAVE_KERBEROS_TGT:
- if (!options.kerberos_tgt_passing) {
- /* packet_get_all(); */
- verbose("Kerberos tgt passing disabled.");
- break;
- } else {
- /* Accept Kerberos tgt. */
- char *tgt = packet_get_string(&dlen);
- packet_integrity_check(plen, 4 + dlen, type);
- if (!auth_kerberos_tgt(pw, tgt))
- verbose("Kerberos tgt REFUSED for %s", pw->pw_name);
- xfree(tgt);
- }
- continue;
+ return expand_filename(options.authorized_keys_file, pw);
+}
- case SSH_CMSG_HAVE_AFS_TOKEN:
- if (!options.afs_token_passing || !k_hasafs()) {
- /* packet_get_all(); */
- verbose("AFS token passing disabled.");
- break;
- } else {
- /* Accept AFS token. */
- char *token_string = packet_get_string(&dlen);
- packet_integrity_check(plen, 4 + dlen, type);
- if (!auth_afs_token(pw, token_string))
- verbose("AFS token REFUSED for %s", pw->pw_name);
- xfree(token_string);
- }
- continue;
-#endif /* AFS */
-#ifdef KRB4
- case SSH_CMSG_AUTH_KERBEROS:
- if (!options.kerberos_authentication) {
- /* packet_get_all(); */
- verbose("Kerberos authentication disabled.");
- break;
- } else {
- /* Try Kerberos v4 authentication. */
- KTEXT_ST auth;
- char *tkt_user = NULL;
- char *kdata = packet_get_string((unsigned int *) &auth.length);
- packet_integrity_check(plen, 4 + auth.length, type);
-
- if (auth.length < MAX_KTXT_LEN)
- memcpy(auth.dat, kdata, auth.length);
- xfree(kdata);
-
- authenticated = auth_krb4(pw->pw_name, &auth, &tkt_user);
-
- if (authenticated) {
- snprintf(user, sizeof user, " tktuser %s", tkt_user);
- xfree(tkt_user);
- }
- }
- break;
-#endif /* KRB4 */
+char *
+authorized_keys_file2(struct passwd *pw)
+{
+ return expand_filename(options.authorized_keys_file2, pw);
+}
- case SSH_CMSG_AUTH_RHOSTS:
- if (!options.rhosts_authentication) {
- verbose("Rhosts authentication disabled.");
- break;
- }
- /*
- * Get client user name. Note that we just have to
- * trust the client; this is one reason why rhosts
- * authentication is insecure. (Another is
- * IP-spoofing on a local network.)
- */
- client_user = packet_get_string(&ulen);
- packet_integrity_check(plen, 4 + ulen, type);
-
- /* Try to authenticate using /etc/hosts.equiv and
- .rhosts. */
- authenticated = auth_rhosts(pw, client_user);
-
- snprintf(user, sizeof user, " ruser %s", client_user);
- break;
+/* 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);
- case SSH_CMSG_AUTH_RHOSTS_RSA:
- if (!options.rhosts_rsa_authentication) {
- verbose("Rhosts with RSA authentication disabled.");
- break;
- }
- /*
- * Get client user name. Note that we just have to
- * trust the client; root on the client machine can
- * claim to be any user.
- */
- client_user = packet_get_string(&ulen);
-
- /* Get the client host key. */
- client_host_key = RSA_new();
- if (client_host_key == NULL)
- fatal("RSA_new failed");
- client_host_key->e = BN_new();
- client_host_key->n = BN_new();
- if (client_host_key->e == NULL || client_host_key->n == NULL)
- fatal("BN_new failed");
- bits = packet_get_int();
- packet_get_bignum(client_host_key->e, &elen);
- packet_get_bignum(client_host_key->n, &nlen);
-
- if (bits != BN_num_bits(client_host_key->n))
- error("Warning: keysize mismatch for client_host_key: "
- "actual %d, announced %d", BN_num_bits(client_host_key->n), bits);
- packet_integrity_check(plen, (4 + ulen) + 4 + elen + nlen, type);
-
- authenticated = auth_rhosts_rsa(pw, client_user, client_host_key);
- RSA_free(client_host_key);
-
- snprintf(user, sizeof user, " ruser %s", client_user);
- break;
+ debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
+ "ok" : "not found", host);
+ return host_status;
+}
- case SSH_CMSG_AUTH_RSA:
- if (!options.rsa_authentication) {
- verbose("RSA authentication disabled.");
- break;
- }
- /* RSA authentication requested. */
- n = BN_new();
- packet_get_bignum(n, &nlen);
- packet_integrity_check(plen, nlen, type);
- authenticated = auth_rsa(pw, n);
- BN_clear_free(n);
- break;
- case SSH_CMSG_AUTH_PASSWORD:
- if (!options.password_authentication) {
- verbose("Password authentication disabled.");
- break;
- }
- /*
- * Read user password. It is in plain text, but was
- * transmitted over the encrypted channel so it is
- * not visible to an outside observer.
- */
- password = packet_get_string(&dlen);
- packet_integrity_check(plen, 4 + dlen, type);
-
-#ifdef USE_PAM
- /* Do PAM auth with password */
- authenticated = auth_pam_password(pw, password);
-#else /* USE_PAM */
- /* Try authentication with the password. */
- authenticated = auth_password(pw, password);
-#endif /* USE_PAM */
- memset(password, 0, strlen(password));
- xfree(password);
- break;
+/*
+ * 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;
-#ifdef SKEY
- case SSH_CMSG_AUTH_TIS:
- debug("rcvd SSH_CMSG_AUTH_TIS");
- if (options.skey_authentication == 1) {
- char *skeyinfo = skey_keyinfo(pw->pw_name);
- if (skeyinfo == NULL) {
- debug("generating fake skeyinfo for %.100s.", pw->pw_name);
- skeyinfo = skey_fake_keyinfo(pw->pw_name);
- }
- if (skeyinfo != NULL) {
- /* we send our s/key- in tis-challenge messages */
- debug("sending challenge '%s'", skeyinfo);
- packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE);
- packet_put_string(skeyinfo, strlen(skeyinfo));
- packet_send();
- packet_write_wait();
- continue;
- }
- }
- break;
- case SSH_CMSG_AUTH_TIS_RESPONSE:
- debug("rcvd SSH_CMSG_AUTH_TIS_RESPONSE");
- if (options.skey_authentication == 1) {
- char *response = packet_get_string(&dlen);
- debug("skey response == '%s'", response);
- packet_integrity_check(plen, 4 + dlen, type);
- authenticated = (skey_haskey(pw->pw_name) == 0 &&
- skey_passcheck(pw->pw_name, response) != -1);
- xfree(response);
- }
- break;
-#else
- case SSH_CMSG_AUTH_TIS:
- /* TIS Authentication is unsupported */
- log("TIS authentication unsupported.");
- break;
-#endif
+ 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;
+ }
- default:
- /*
- * Any unknown messages will be ignored (and failure
- * returned) during authentication.
- */
- log("Unknown message during authentication: type %d", type);
- break;
- }
+ /* 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;
+ }
- /*
- * Check if the user is logging in as root and root logins
- * are disallowed.
- * Note that root login is allowed for forced commands.
- */
- if (authenticated && pw->pw_uid == 0 && !options.permit_root_login) {
- if (forced_command) {
- log("Root login accepted for forced command.");
- } else {
- authenticated = 0;
- log("ROOT LOGIN REFUSED FROM %.200s",
- get_canonical_hostname());
- }
- }
-
- /* Raise logging level */
- if (authenticated ||
- attempt == AUTH_FAIL_LOG ||
- type == SSH_CMSG_AUTH_PASSWORD)
- authlog = log;
-
- authlog("%s %s for %.200s from %.200s port %d%s",
- authenticated ? "Accepted" : "Failed",
- get_authname(type),
- pw->pw_uid == 0 ? "ROOT" : pw->pw_name,
- get_remote_ipaddr(),
- get_remote_port(),
- user);
-
-#ifdef USE_PAM
- if (authenticated) {
- if (!do_pam_account(pw->pw_name, client_user)) {
- if (client_user != NULL) {
- xfree(client_user);
- client_user = NULL;
- }
- do_fake_authloop1(pw->pw_name);
- }
- return;
+ /* for each component of the canonical path, walking upwards */
+ for (;;) {
+ if ((cp = dirname(buf)) == NULL) {
+ snprintf(err, errlen, "dirname() failed");
+ return -1;
}
-#else /* USE_PAM */
- if (authenticated) {
- return;
+ 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;
}
-#endif /* USE_PAM */
- if (client_user != NULL) {
- xfree(client_user);
- client_user = NULL;
+ /* 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;
+}
- if (attempt > AUTH_FAIL_MAX)
- packet_disconnect(AUTH_FAIL_MSG, pw->pw_name);
+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;
- /* Send a message indicating that the authentication attempt failed. */
- packet_start(SSH_SMSG_FAILURE);
- packet_send();
- packet_write_wait();
+ 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(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);
}
-/*
- * Performs authentication of an incoming connection. Session key has already
- * been exchanged and encryption is enabled.
- */
void
-do_authentication()
+auth_debug_add(const char *fmt,...)
{
- struct passwd *pw, pwcopy;
- int plen;
- unsigned int ulen;
- char *user;
-#ifdef WITH_AIXAUTHENTICATE
- char *loginmsg;
-#endif /* WITH_AIXAUTHENTICATE */
-
- /* Get the name of the user that we wish to log in as. */
- packet_read_expect(&plen, SSH_CMSG_USER);
+ char buf[1024];
+ va_list args;
- /* Get the user name. */
- user = packet_get_string(&ulen);
- packet_integrity_check(plen, (4 + ulen), SSH_CMSG_USER);
+ if (!auth_debug_init)
+ return;
- setproctitle("%s", user);
+ va_start(args, fmt);
+ vsnprintf(buf, sizeof(buf), fmt, args);
+ va_end(args);
+ buffer_put_cstring(&auth_debug, buf);
+}
-#ifdef AFS
- /* If machine has AFS, set process authentication group. */
- if (k_hasafs()) {
- k_setpag();
- k_unlog();
+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);
}
-#endif /* AFS */
-
- /* Verify that the user is a valid user. */
- pw = getpwnam(user);
- if (!pw || !allowed_user(pw))
- do_fake_authloop1(user);
- xfree(user);
-
- /* Take a copy of the returned structure. */
- memset(&pwcopy, 0, sizeof(pwcopy));
- pwcopy.pw_name = xstrdup(pw->pw_name);
- pwcopy.pw_passwd = xstrdup(pw->pw_passwd);
- pwcopy.pw_uid = pw->pw_uid;
- pwcopy.pw_gid = pw->pw_gid;
- pwcopy.pw_dir = xstrdup(pw->pw_dir);
- pwcopy.pw_shell = xstrdup(pw->pw_shell);
- pw = &pwcopy;
-
-#ifdef USE_PAM
- start_pam(pw);
-#endif
+}
- /*
- * If we are not running as root, the user must have the same uid as
- * the server.
- */
- if (getuid() != 0 && pw->pw_uid != getuid())
- packet_disconnect("Cannot change user when server not running as root.");
-
- debug("Attempting authentication for %.100s.", pw->pw_name);
-
- /* If the user has no password, accept authentication immediately. */
- if (options.password_authentication &&
-#ifdef KRB4
- (!options.kerberos_authentication || options.kerberos_or_local_passwd) &&
-#endif /* KRB4 */
-#ifdef USE_PAM
- auth_pam_password(pw, "")) {
-#else /* USE_PAM */
- auth_password(pw, "")) {
-#endif /* USE_PAM */
- /* Authentication with empty password succeeded. */
- log("Login for user %s from %.100s, accepted without authentication.",
- pw->pw_name, get_remote_ipaddr());
- } else {
- /* Loop until the user has been authenticated or the
- connection is closed, do_authloop() returns only if
- authentication is successfull */
- do_authloop(pw);
+void
+auth_debug_reset(void)
+{
+ if (auth_debug_init)
+ buffer_clear(&auth_debug);
+ else {
+ buffer_init(&auth_debug);
+ auth_debug_init = 1;
}
-
- /* The user has been authenticated and accepted. */
-#ifdef WITH_AIXAUTHENTICATE
- loginsuccess(user,get_canonical_hostname(),"ssh",&loginmsg);
-#endif /* WITH_AIXAUTHENTICATE */
- packet_start(SSH_SMSG_SUCCESS);
- packet_send();
- packet_write_wait();
-
- /* Perform session preparation. */
- do_authenticated(pw);
}
andersk / openssh.git / blobdiff