libmount: don't remove user= when executed by root

The original mount(8) allows to store arbitrary user= option to mtab
file if called by root user. For example:

  # mount -f foo /bar -t xxx -o rw,user=kzak

the new mount removes the 'user=' and 'users' options at all for root
user. This is regression. The original functionality is necessary by
'sshfs' where fuse writes to mtab file by mount(8).

Reported-by: Juergen Daubert <jue@jue.li> (and 'horrorStruck' on IRC)
Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/libmount/src/context_mount.c b/libmount/src/context_mount.c
index fdb459c32350f76e1437724e4d993bf1078c3785..c665a05784f5b157403e63df018d13637a8f2adc 100644 (file)
--- a/libmount/src/context_mount.c
+++ b/libmount/src/context_mount.c
@@ -58,12 +58,10 @@ static int fix_optstr(struct libmnt_context *cxt)
         * but exception is command line for /sbin/mount.<type> helpers. Let's
         * save the original user=<name> to call the helpers with unchanged
         * "user" setting.
-        *
-        * Don't check for MNT_MS_USER in cxt->user_mountflags, the flag maybe
-        * removed by evaluate_permissions().
         */
-       if (!mnt_optstr_get_option(fs->user_optstr, "user", &val, &valsz)) {
-               if (val) {
+       if (cxt->user_mountflags & MNT_MS_USER) {
+               if (!mnt_optstr_get_option(fs->user_optstr,
+                                       "user", &val, &valsz) && val) {
                        cxt->orig_user = strndup(val, valsz);
                        if (!cxt->orig_user) {
                                rc = -ENOMEM;
@@ -157,7 +155,7 @@ static int fix_optstr(struct libmnt_context *cxt)
                        goto done;
        }
 
-       if (!rc && cxt->user_mountflags & MNT_MS_USER)
+       if (!rc && cxt->restricted && (cxt->user_mountflags & MNT_MS_USER))
                rc = mnt_optstr_fix_user(&fs->user_optstr);
 
        /* refresh merged optstr */
@@ -256,8 +254,6 @@ static int evaluate_permissions(struct libmnt_context *cxt)
                 */
                cxt->user_mountflags &= ~MNT_MS_OWNER;
                cxt->user_mountflags &= ~MNT_MS_GROUP;
-               cxt->user_mountflags &= ~MNT_MS_USER;
-               cxt->user_mountflags &= ~MNT_MS_USERS;
        } else {
                /*
                 * user mount