$NetBSD: patch-ab,v 1.1.1.1 2004/11/19 18:07:42 daprice Exp $

--- chrsh.c.orig	Thu Jul 10 11:55:31 2003
+++ chrsh.c
@@ -80,6 +80,7 @@
 /* The chroot jail main directory must be owned and permissioned thus */
 #define JAILDIRUID	0
 #define JAILDIRGID	0
+#define JAILMNT         MNT_RDONLY
 #define JAILDIRMODE	0555
 
 /* The jailed user's chrooted home directory must be this mode */
@@ -116,6 +117,7 @@
 # error "You MUST define either LOG_USESYSLOG or LOG_USEFILE (not both)!"
 #endif
 
+#include <errno.h>
 #include <string.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -126,6 +128,7 @@
 #include <unistd.h>
 #include <stdarg.h>
 #include <sys/param.h>
+#include <sys/mount.h>
 #include <fcntl.h>
 #include <sys/errno.h>
 #include <netinet/in.h>
@@ -255,8 +258,9 @@ void clean_exit(int exitcode) {
  *  are world writable, race conditions and worse WILL almost CERTAINLY
  *  end up in a root compromise.
  */
-int checkjailed(char *item, uid_t uid, gid_t gid, int isdir, mode_t mode) {
+int checkjailed(char *item, uid_t uid, gid_t gid, int isdir, int fs_flags, mode_t mode) {
 	struct stat statinfo;
+	struct statfs statfsinfo;
 	char *type;
 
 	type = isdir ? "subdirectory" : "file";
@@ -265,6 +269,10 @@ int checkjailed(char *item, uid_t uid, g
 		do_log(LOG_WARNING, "Unable to stat %s %s of the jail.", item, type);
 		return 1;
 	}
+	if (statfs(item, &statfsinfo)) {
+               do_log(LOG_WARNING, "Unable to statfs %s %s of the jail.", item, type);
+               return 1;
+       	}
 	if ((!(statinfo.st_mode & S_IFDIR) && isdir) || (!(statinfo.st_mode & S_IFREG) && !isdir)) {
 		do_log(LOG_WARNING, "Jailed %s %s is not a %s.", item, type, (isdir ? "directory" : "regular file"));
 		return 2;
@@ -273,9 +281,12 @@ int checkjailed(char *item, uid_t uid, g
 		do_log(LOG_WARNING, "Jailed %s %s is world writable.", item, type);
 		return 3;
 	}
-	if ((statinfo.st_mode & ALLPERMS) != mode) {
-		do_log(LOG_WARNING, "Jailed %s %s mode does not match expected mode %lo.", item, type, mode);
-		return 4;
+	if ((statfsinfo.f_flags & fs_flags) == 0) {
+               if ((statinfo.st_mode & ALLPERMS) != mode) {
+                       do_log(LOG_WARNING, "Jailed %s %s mode does not match expected mode %lo.", item, type, mode);
+                       return 4;
+               }
+
 	}
 	if (statinfo.st_uid != uid) {
 		do_log(LOG_WARNING, "Jailed %s %s is not owned by expected UID %ld.", item, type, uid);
@@ -310,6 +321,7 @@ int main(int argc, char *argv[], char *e
 	struct passwd *pw;
 	struct group *gr;
 	struct stat statinfo;
+	struct statfs statfsinfo;
 	struct sockaddr sock;
 	int m, i;
 	int logfd = -1;
@@ -558,13 +570,19 @@ int main(int argc, char *argv[], char *e
 		do_log(LOG_WARNING, "Unable to stat the jail directory: %s", jail);
 		clean_exit(185);
 	}
+	if (statfs(jail, &statfsinfo)) {
+               do_log(LOG_WARNING, "Unable to statfs the jail directory: %s", jail);
+               clean_exit(185);
+        } 
 	if (statinfo.st_mode & (S_IWGRP | S_IWOTH)) {
 		do_log(LOG_WARNING, "Jail directory is world writable.");
 		clean_exit(186);
 	}
-	if ((statinfo.st_mode & ALLPERMS) != JAILDIRMODE) {
-		do_log(LOG_WARNING, "Jail directory mode does not match expected mode %lo.", JAILDIRMODE);
-		clean_exit(187);
+	if ((statfsinfo.f_flags & JAILMNT) == 0) {
+               if ((statinfo.st_mode & ALLPERMS) != JAILDIRMODE) {
+                       do_log(LOG_WARNING, "Jail directory mode does not match expected mode %lo.", JAILDIRMODE);
+                       clean_exit(187);
+               }
 	}
 	if (statinfo.st_uid != JAILDIRUID) {
 		do_log(LOG_WARNING, "Jail directory is not owned by expected UID %ld.", JAILDIRUID);
@@ -587,17 +605,17 @@ int main(int argc, char *argv[], char *e
 	/*
 	 * Now look for and check out /bin and /etc in the jail...
 	 */
-	if ((m = checkjailed("/etc", JAILDIRUID, JAILDIRGID, 1, JAILDIRMODE)) != 0) {
+	if ((m = checkjailed("/etc", JAILDIRUID, JAILDIRGID, 1, JAILMNT, JAILDIRMODE)) != 0) {
 		clean_exit(m+200);
 	}
-	if ((m = checkjailed("/bin", JAILDIRUID, JAILDIRGID, 1, JAILDIRMODE)) != 0) {
+	if ((m = checkjailed("/bin", JAILDIRUID, JAILDIRGID, 1, JAILMNT, JAILDIRMODE)) != 0) {
 		clean_exit(m+210);
 	}
 
 	/*
 	 * Check out the user's home subdir in the jail...
 	 */
-	if ((m = checkjailed(home, uid, gid, 1, HOMEDIRMODE)) != 0) {
+	if ((m = checkjailed(home, uid, gid, 1, JAILMNT, HOMEDIRMODE)) != 0) {
 		 clean_exit(m+220);
 	}
 
@@ -644,7 +662,7 @@ int main(int argc, char *argv[], char *e
 		do_log(LOG_WARNING, "Unable to allocate space for user's jailed shell \"%s\".", pw->pw_shell);
 		clean_exit(241);
 	}
-	if ((m = checkjailed(shell, SHELLUID, SHELLGID, 0, SHELLMODE)) != 0) {
+	if ((m = checkjailed(shell, SHELLUID, SHELLGID, 0, JAILMNT, SHELLMODE)) != 0) {
 		clean_exit(242+m);
 	}