ismounted.c (check_mntent_file): We now validate the entry in

	/etc/mtab to make sure the filesystem is really mounted,
	since some broken distributions (read: Slackware) have
	buggy boot scripts that don't initialize /etc/mtab before
	checking non-root filesystems.  (Slackware also doesn't
	check the root filesystem separately, and reboot if the
	root filesystem had changes applied to it, which is
	dangerous and broken.)

diff --git a/lib/ext2fs/ChangeLog b/lib/ext2fs/ChangeLog
index 87ff9f04bb9daf07626926526342ed9f2499c1f8..28f799cd36bc439411908c9fdf9977f4c6c0e6ce 100644 (file)
--- a/lib/ext2fs/ChangeLog
+++ b/lib/ext2fs/ChangeLog
@@ -4,6 +4,17 @@
                which was breaking the build on the Hurd.  (Addresses
                Debian bug #112414).
 
+2001-09-13  Theodore Ts'o  <tytso@valinux.com>
+
+       * ismounted.c (check_mntent_file): We now validate the entry in
+               /etc/mtab to make sure the filesystem is really mounted,
+               since some broken distributions (read: Slackware) have
+               buggy boot scripts that don't initialize /etc/mtab before
+               checking non-root filesystems.  (Slackware also doesn't
+               check the root filesystem separately, and reboot if the
+               root filesystem had changes applied to it, which is
+               dangerous and broken.)   
+
 2001-09-02  Theodore Tso  <tytso@thunk.org>
 
        * Release of E2fsprogs 1.24a

diff --git a/lib/ext2fs/ismounted.c b/lib/ext2fs/ismounted.c
index ac785c6baeeddbfd208557c7cd6599423d6f3728..1b145c663fefbbe8311993b7e98acd8da63c48b3 100644 (file)
--- a/lib/ext2fs/ismounted.c
+++ b/lib/ext2fs/ismounted.c
@@ -43,9 +43,11 @@
 static errcode_t check_mntent_file(const char *mtab_file, const char *file, 
                                   int *mount_flags, char *mtpt, int mtlen)
 {
-       FILE * f;
-       struct mntent * mnt;
-       int     fd;
+       struct mntent   *mnt;
+       struct stat     st_mntpnt, st_file;
+       errcode_t       retval = 0;
+       FILE            *f;
+       int             fd;
 
        *mount_flags = 0;
        if ((f = setmntent (mtab_file, "r")) == NULL)
@@ -56,16 +58,15 @@ static errcode_t check_mntent_file(const char *mtab_file, const char *file,
 
        if (mnt == 0) {
 #ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */
-               struct stat st_root, st_file;
                /*
                 * Do an extra check to see if this is the root device.  We
-                * can't trust /etc/fstab, and /proc/mounts will only list
+                * can't trust /etc/mtab, and /proc/mounts will only list
                 * /dev/root for the root filesystem.  Argh.  Instead we
                 * check if the given device has the same major/minor number
                 * as the device that the root directory is on.
                 */
-               if (stat("/", &st_root) == 0 && stat(file, &st_file) == 0) {
-                       if (st_root.st_dev == st_file.st_rdev) {
+               if (stat("/", &st_mntpnt) == 0 && stat(file, &st_file) == 0) {
+                       if (st_mntpnt.st_dev == st_file.st_rdev) {
                                *mount_flags = EXT2_MF_MOUNTED;
                                if (mtpt)
                                        strncpy(mtpt, "/", mtlen);
@@ -73,9 +74,36 @@ static errcode_t check_mntent_file(const char *mtab_file, const char *file,
                        }
                }
 #endif
-               endmntent (f);
-               return 0;
+               goto exit;
+       }
+#ifndef __GNU__ /* The GNU hurd is deficient; what else is new? */
+       /* Validate the entry in case /etc/mtab is out of date */
+       /* 
+        * We need to be paranoid, because some broken distributions
+        * (read: Slackware) don't initialize /etc/mtab before checking
+        * all of the non-root filesystems on the disk.
+        */
+       if (stat(mnt->mnt_dir, &st_mntpnt) < 0) {
+               retval = errno;
+               if (retval == ENOENT) {
+#ifdef DEBUG
+                       printf("Bogus entry in %s!  (%s does not exist)\n",
+                              mtab_file, mnt->mnt_dir);
+#endif
+                       retval = 0;
+               }
+               goto exit;
+       }
+       if (stat(file, &st_file) == 0) {
+               if (st_mntpnt.st_dev != st_file.st_rdev) {
+#ifdef DEBUG
+                       printf("Bogus entry in %s!  (%s not mounted on %s)\n",
+                              mtab_file, file, mnt->mnt_dir);
+#endif
+                       goto exit;
+               }
        }
+#endif
        *mount_flags = EXT2_MF_MOUNTED;
        
        /* Check to see if the ro option is set */
@@ -102,8 +130,10 @@ is_root:
                        close(fd);
                (void) unlink(TEST_FILE);
        }
+       retval = 0;
+exit:
        endmntent (f);
-       return 0;
+       return retval;
 }
 
 static errcode_t check_mntent(const char *file, int *mount_flags,
@@ -111,6 +141,12 @@ static errcode_t check_mntent(const char *file, int *mount_flags,
 {
        errcode_t       retval;
 
+#ifdef DEBUG
+       retval = check_mntent_file("/tmp/mtab", file, mount_flags,
+                                  mtpt, mtlen);
+       if (retval == 0)
+               return 0;
+#endif
 #ifdef __linux__
        retval = check_mntent_file("/proc/mounts", file, mount_flags,
                                   mtpt, mtlen);