===================================================================
RCS file: /cvsrepo/anoncvs/cvs/src/usr.bin/ssh/auth.c,v
retrieving revision 1.11
retrieving revision 1.11.2.6
diff -u -r1.11 -r1.11.2.6
--- src/usr.bin/ssh/auth.c	2000/10/11 20:27:23	1.11
+++ src/usr.bin/ssh/auth.c	2001/11/15 00:14:59	1.11.2.6
@@ -1,16 +1,6 @@
 /*
- * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
- *                    All rights reserved
+ * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  *
- * As far as I am concerned, the code I have written for this software
- * can be used freely for any purpose.  Any derived versions of this
- * software must be clearly marked as such, and if the derived work is
- * incompatible with the protocol description in the RFC file, it must be
- * called by a name other than "ssh" or "Secure Shell".
- *
- *
- * 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:
@@ -33,34 +23,32 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: auth.c,v 1.11 2000/10/11 20:27:23 markus Exp $");
+RCSID("$OpenBSD: auth.c,v 1.11.2.6 2001/11/15 00:14:59 miod Exp $");
 
+#include <libgen.h>
+
 #include "xmalloc.h"
-#include "rsa.h"
-#include "ssh.h"
-#include "pty.h"
-#include "packet.h"
-#include "buffer.h"
-#include "mpaux.h"
-#include "servconf.h"
-#include "compat.h"
-#include "channels.h"
 #include "match.h"
-
-#include "bufaux.h"
-#include "ssh2.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;
 
 /*
- * 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.
  */
@@ -68,12 +56,12 @@
 allowed_user(struct passwd * pw)
 {
 	struct stat st;
-	struct group *grp;
+	const char *hostname = NULL, *ipaddr = NULL;
 	char *shell;
 	int i;
 
 	/* Shouldn't be called if pw is NULL, but better safe than sorry... */
-	if (!pw)
+	if (!pw || !pw->pw_name)
 		return 0;
 
 	/*
@@ -88,55 +76,294 @@
 	if (!((st.st_mode & S_IFREG) && (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP))))
 		return 0;
 
+	if (options.num_deny_users > 0 || options.num_allow_users > 0) {
+		hostname = get_canonical_hostname(options.reverse_mapping_check);
+		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]))
 				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)
 			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)
 			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();
 				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)
+		if (options.num_allow_groups > 0)
+			if (!ga_match(options.allow_groups,
+			    options.num_allow_groups)) {
+				ga_free();
 				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)
-				return 0;
-		}
+			}
+		ga_free();
 	}
 	/* 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->valid && authctxt->pw->pw_uid == 0 ? "ROOT" : 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;
+	int 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;
 }