Vendor import of OpenSSH.

1 files changed, 266 insertions, 0 deletions

diff --git a/crypto/openssh/auth-rhosts.c b/crypto/openssh/auth-rhosts.c
new file mode 100644
index 0000000..8432428
--- /dev/null
+++ b/crypto/openssh/auth-rhosts.c
@@ -0,0 +1,266 @@
+/*
+ * 
+ * auth-rhosts.c
+ * 
+ * Author: Tatu Ylonen <ylo@cs.hut.fi>
+ * 
+ * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
+ *                    All rights reserved
+ * 
+ * Created: Fri Mar 17 05:12:18 1995 ylo
+ * 
+ * Rhosts authentication.  This file contains code to check whether to admit
+ * the login based on rhosts authentication.  This file also processes
+ * /etc/hosts.equiv.
+ * 
+ */
+
+#include "includes.h"
+RCSID("$Id: auth-rhosts.c,v 1.12 1999/12/27 10:46:11 markus Exp $");
+
+#include "packet.h"
+#include "ssh.h"
+#include "xmalloc.h"
+#include "uidswap.h"
+#include "servconf.h"
+
+/*
+ * This function processes an rhosts-style file (.rhosts, .shosts, or
+ * /etc/hosts.equiv).  This returns true if authentication can be granted
+ * based on the file, and returns zero otherwise.
+ */
+
+int 
+check_rhosts_file(const char *filename, const char *hostname,
+		  const char *ipaddr, const char *client_user,
+		  const char *server_user)
+{
+	FILE *f;
+	char buf[1024];	/* Must not be larger than host, user, dummy below. */
+
+	/* Open the .rhosts file, deny if unreadable */
+	f = fopen(filename, "r");
+	if (!f)
+		return 0;
+
+	while (fgets(buf, sizeof(buf), f)) {
+		/* All three must be at least as big as buf to avoid overflows. */
+		char hostbuf[1024], userbuf[1024], dummy[1024], *host, *user, *cp;
+		int negated;
+
+		for (cp = buf; *cp == ' ' || *cp == '\t'; cp++)
+			;
+		if (*cp == '#' || *cp == '\n' || !*cp)
+			continue;
+
+		/*
+		 * NO_PLUS is supported at least on OSF/1.  We skip it (we
+		 * don't ever support the plus syntax).
+		 */
+		if (strncmp(cp, "NO_PLUS", 7) == 0)
+			continue;
+
+		/*
+		 * This should be safe because each buffer is as big as the
+		 * whole string, and thus cannot be overwritten.
+		 */
+		switch (sscanf(buf, "%s %s %s", hostbuf, userbuf, dummy)) {
+		case 0:
+			packet_send_debug("Found empty line in %.100s.", filename);
+			continue;
+		case 1:
+			/* Host name only. */
+			strlcpy(userbuf, server_user, sizeof(userbuf));
+			break;
+		case 2:
+			/* Got both host and user name. */
+			break;
+		case 3:
+			packet_send_debug("Found garbage in %.100s.", filename);
+			continue;
+		default:
+			/* Weird... */
+			continue;
+		}
+
+		host = hostbuf;
+		user = userbuf;
+		negated = 0;
+
+		/* Process negated host names, or positive netgroups. */
+		if (host[0] == '-') {
+			negated = 1;
+			host++;
+		} else if (host[0] == '+')
+			host++;
+
+		if (user[0] == '-') {
+			negated = 1;
+			user++;
+		} else if (user[0] == '+')
+			user++;
+
+		/* Check for empty host/user names (particularly '+'). */
+		if (!host[0] || !user[0]) {
+			/* We come here if either was '+' or '-'. */
+			packet_send_debug("Ignoring wild host/user names in %.100s.",
+					  filename);
+			continue;
+		}
+		/* Verify that host name matches. */
+		if (host[0] == '@') {
+			if (!innetgr(host + 1, hostname, NULL, NULL) &&
+			    !innetgr(host + 1, ipaddr, NULL, NULL))
+				continue;
+		} else if (strcasecmp(host, hostname) && strcmp(host, ipaddr) != 0)
+			continue;	/* Different hostname. */
+
+		/* Verify that user name matches. */
+		if (user[0] == '@') {
+			if (!innetgr(user + 1, NULL, client_user, NULL))
+				continue;
+		} else if (strcmp(user, client_user) != 0)
+			continue;	/* Different username. */
+
+		/* Found the user and host. */
+		fclose(f);
+
+		/* If the entry was negated, deny access. */
+		if (negated) {
+			packet_send_debug("Matched negative entry in %.100s.",
+					  filename);
+			return 0;
+		}
+		/* Accept authentication. */
+		return 1;
+	}
+
+	/* Authentication using this file denied. */
+	fclose(f);
+	return 0;
+}
+
+/*
+ * Tries to authenticate the user using the .shosts or .rhosts file. Returns
+ * true if authentication succeeds.  If ignore_rhosts is true, only
+ * /etc/hosts.equiv will be considered (.rhosts and .shosts are ignored).
+ */
+
+int 
+auth_rhosts(struct passwd *pw, const char *client_user)
+{
+	extern ServerOptions options;
+	char buf[1024];
+	const char *hostname, *ipaddr;
+	struct stat st;
+	static const char *rhosts_files[] = {".shosts", ".rhosts", NULL};
+	unsigned int rhosts_file_index;
+
+	/* Switch to the user's uid. */
+	temporarily_use_uid(pw->pw_uid);
+	/*
+	 * Quick check: if the user has no .shosts or .rhosts files, return
+	 * failure immediately without doing costly lookups from name
+	 * servers.
+	 */
+	for (rhosts_file_index = 0; rhosts_files[rhosts_file_index];
+	     rhosts_file_index++) {
+		/* Check users .rhosts or .shosts. */
+		snprintf(buf, sizeof buf, "%.500s/%.100s",
+			 pw->pw_dir, rhosts_files[rhosts_file_index]);
+		if (stat(buf, &st) >= 0)
+			break;
+	}
+	/* Switch back to privileged uid. */
+	restore_uid();
+
+	/* Deny if The user has no .shosts or .rhosts file and there are no system-wide files. */
+	if (!rhosts_files[rhosts_file_index] &&
+	    stat("/etc/hosts.equiv", &st) < 0 &&
+	    stat(SSH_HOSTS_EQUIV, &st) < 0)
+		return 0;
+
+	hostname = get_canonical_hostname();
+	ipaddr = get_remote_ipaddr();
+
+	/* If not logging in as superuser, try /etc/hosts.equiv and shosts.equiv. */
+	if (pw->pw_uid != 0) {
+		if (check_rhosts_file("/etc/hosts.equiv", hostname, ipaddr, client_user,
+				      pw->pw_name)) {
+			packet_send_debug("Accepted for %.100s [%.100s] by /etc/hosts.equiv.",
+					  hostname, ipaddr);
+			return 1;
+		}
+		if (check_rhosts_file(SSH_HOSTS_EQUIV, hostname, ipaddr, client_user,
+				      pw->pw_name)) {
+			packet_send_debug("Accepted for %.100s [%.100s] by %.100s.",
+				      hostname, ipaddr, SSH_HOSTS_EQUIV);
+			return 1;
+		}
+	}
+	/*
+	 * Check that the home directory is owned by root or the user, and is
+	 * not group or world writable.
+	 */
+	if (stat(pw->pw_dir, &st) < 0) {
+		log("Rhosts authentication refused for %.100s: no home directory %.200s",
+		    pw->pw_name, pw->pw_dir);
+		packet_send_debug("Rhosts authentication refused for %.100s: no home directory %.200s",
+				  pw->pw_name, pw->pw_dir);
+		return 0;
+	}
+	if (options.strict_modes &&
+	    ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
+	     (st.st_mode & 022) != 0)) {
+		log("Rhosts authentication refused for %.100s: bad ownership or modes for home directory.",
+		    pw->pw_name);
+		packet_send_debug("Rhosts authentication refused for %.100s: bad ownership or modes for home directory.",
+				  pw->pw_name);
+		return 0;
+	}
+	/* Temporarily use the user's uid. */
+	temporarily_use_uid(pw->pw_uid);
+
+	/* Check all .rhosts files (currently .shosts and .rhosts). */
+	for (rhosts_file_index = 0; rhosts_files[rhosts_file_index];
+	     rhosts_file_index++) {
+		/* Check users .rhosts or .shosts. */
+		snprintf(buf, sizeof buf, "%.500s/%.100s",
+			 pw->pw_dir, rhosts_files[rhosts_file_index]);
+		if (stat(buf, &st) < 0)
+			continue;
+
+		/*
+		 * Make sure that the file is either owned by the user or by
+		 * root, and make sure it is not writable by anyone but the
+		 * owner.  This is to help avoid novices accidentally
+		 * allowing access to their account by anyone.
+		 */
+		if (options.strict_modes &&
+		    ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
+		     (st.st_mode & 022) != 0)) {
+			log("Rhosts authentication refused for %.100s: bad modes for %.200s",
+			    pw->pw_name, buf);
+			packet_send_debug("Bad file modes for %.200s", buf);
+			continue;
+		}
+		/* Check if we have been configured to ignore .rhosts and .shosts files. */
+		if (options.ignore_rhosts) {
+			packet_send_debug("Server has been configured to ignore %.100s.",
+					  rhosts_files[rhosts_file_index]);
+			continue;
+		}
+		/* Check if authentication is permitted by the file. */
+		if (check_rhosts_file(buf, hostname, ipaddr, client_user, pw->pw_name)) {
+			packet_send_debug("Accepted by %.100s.",
+					  rhosts_files[rhosts_file_index]);
+			/* Restore the privileged uid. */
+			restore_uid();
+			return 1;
+		}
+	}
+
+	/* Restore the privileged uid. */
+	restore_uid();
+	return 0;
+}