Adding upstream version 1:9.6p1.upstream/1%9.6p1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 338 insertions, 0 deletions

diff --git a/auth-rhosts.c b/auth-rhosts.c
new file mode 100644
index 0000000..5672467
--- /dev/null
+++ b/auth-rhosts.c
@@ -0,0 +1,338 @@
+/* $OpenBSD: auth-rhosts.c,v 1.57 2022/12/09 00:17:40 dtucker Exp $ */
+/*
+ * Author: Tatu Ylonen <ylo@cs.hut.fi>
+ * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
+ *                    All rights reserved
+ * Rhosts authentication.  This file contains code to check whether to admit
+ * the login based on rhosts authentication.  This file also processes
+ * /etc/hosts.equiv.
+ *
+ * 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".
+ */
+
+#include "includes.h"
+
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#ifdef HAVE_NETGROUP_H
+# include <netgroup.h>
+#endif
+#include <pwd.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdarg.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "packet.h"
+#include "uidswap.h"
+#include "pathnames.h"
+#include "log.h"
+#include "misc.h"
+#include "xmalloc.h"
+#include "sshbuf.h"
+#include "sshkey.h"
+#include "servconf.h"
+#include "canohost.h"
+#include "hostfile.h"
+#include "auth.h"
+
+/* import */
+extern ServerOptions options;
+extern int use_privsep;
+
+/*
+ * 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.
+ */
+
+static int
+check_rhosts_file(const char *filename, const char *hostname,
+		  const char *ipaddr, const char *client_user,
+		  const char *server_user)
+{
+	FILE *f;
+#define RBUFLN 1024
+	char buf[RBUFLN];/* Must not be larger than host, user, dummy below. */
+	int fd;
+	struct stat st;
+
+	/* Open the .rhosts file, deny if unreadable */
+	if ((fd = open(filename, O_RDONLY|O_NONBLOCK)) == -1)
+		return 0;
+	if (fstat(fd, &st) == -1) {
+		close(fd);
+		return 0;
+	}
+	if (!S_ISREG(st.st_mode)) {
+		logit("User %s hosts file %s is not a regular file",
+		    server_user, filename);
+		close(fd);
+		return 0;
+	}
+	unset_nonblock(fd);
+	if ((f = fdopen(fd, "r")) == NULL) {
+		close(fd);
+		return 0;
+	}
+	while (fgets(buf, sizeof(buf), f)) {
+		/* All three must have length >= buf to avoid overflows. */
+		char hostbuf[RBUFLN], userbuf[RBUFLN], dummy[RBUFLN];
+		char *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, "%1023s %1023s %1023s", hostbuf, userbuf,
+		    dummy)) {
+		case 0:
+			auth_debug_add("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:
+			auth_debug_add("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 '-'. */
+			auth_debug_add("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) {
+			auth_debug_add("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_rhosts2(struct passwd *pw, const char *client_user, const char *hostname,
+    const char *ipaddr)
+{
+	char *path = NULL;
+	struct stat st;
+	static const char * const rhosts_files[] = {".shosts", ".rhosts", NULL};
+	u_int rhosts_file_index;
+	int r;
+
+	debug2_f("clientuser %s hostname %s ipaddr %s",
+	    client_user, hostname, ipaddr);
+
+	/* Switch to the user's uid. */
+	temporarily_use_uid(pw);
+	/*
+	 * Quick check: if the user has no .shosts or .rhosts files and
+	 * no system hosts.equiv/shosts.equiv files exist then 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. */
+		xasprintf(&path, "%s/%s",
+		    pw->pw_dir, rhosts_files[rhosts_file_index]);
+		r = stat(path, &st);
+		free(path);
+		if (r >= 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(_PATH_RHOSTS_EQUIV, &st) == -1 &&
+	    stat(_PATH_SSH_HOSTS_EQUIV, &st) == -1) {
+		debug3_f("no hosts access files exist");
+		return 0;
+	}
+
+	/*
+	 * If not logging in as superuser, try /etc/hosts.equiv and
+	 * shosts.equiv.
+	 */
+	if (pw->pw_uid == 0)
+		debug3_f("root user, ignoring system hosts files");
+	else {
+		if (check_rhosts_file(_PATH_RHOSTS_EQUIV, hostname, ipaddr,
+		    client_user, pw->pw_name)) {
+			auth_debug_add("Accepted for %.100s [%.100s] by "
+			    "/etc/hosts.equiv.", hostname, ipaddr);
+			return 1;
+		}
+		if (check_rhosts_file(_PATH_SSH_HOSTS_EQUIV, hostname, ipaddr,
+		    client_user, pw->pw_name)) {
+			auth_debug_add("Accepted for %.100s [%.100s] by "
+			    "%.100s.", hostname, ipaddr, _PATH_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) == -1) {
+		logit("Rhosts authentication refused for %.100s: "
+		    "no home directory %.200s", pw->pw_name, pw->pw_dir);
+		auth_debug_add("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)) {
+		logit("Rhosts authentication refused for %.100s: "
+		    "bad ownership or modes for home directory.", pw->pw_name);
+		auth_debug_add("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);
+
+	/* 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. */
+		xasprintf(&path, "%s/%s",
+		    pw->pw_dir, rhosts_files[rhosts_file_index]);
+		if (stat(path, &st) == -1) {
+			debug3_f("stat %s: %s", path, strerror(errno));
+			free(path);
+			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)) {
+			logit("Rhosts authentication refused for %.100s: "
+			    "bad modes for %.200s", pw->pw_name, path);
+			auth_debug_add("Bad file modes for %.200s", path);
+			free(path);
+			continue;
+		}
+		/*
+		 * Check if we have been configured to ignore .rhosts
+		 * and .shosts files.
+		 */
+		if (options.ignore_rhosts == IGNORE_RHOSTS_YES ||
+		    (options.ignore_rhosts == IGNORE_RHOSTS_SHOSTS &&
+		    strcmp(rhosts_files[rhosts_file_index], ".shosts") != 0)) {
+			auth_debug_add("Server has been configured to "
+			    "ignore %.100s.", rhosts_files[rhosts_file_index]);
+			free(path);
+			continue;
+		}
+		/* Check if authentication is permitted by the file. */
+		if (check_rhosts_file(path, hostname, ipaddr,
+		    client_user, pw->pw_name)) {
+			auth_debug_add("Accepted by %.100s.",
+			    rhosts_files[rhosts_file_index]);
+			/* Restore the privileged uid. */
+			restore_uid();
+			auth_debug_add("Accepted host %s ip %s client_user "
+			    "%s server_user %s", hostname, ipaddr,
+			    client_user, pw->pw_name);
+			free(path);
+			return 1;
+		}
+		free(path);
+	}
+
+	/* Restore the privileged uid. */
+	restore_uid();
+	return 0;
+}