libmount: fix x- options use for non-root users

libmount returns EPERM for all X- and x- mount options for non-root
users when evaluate X-mount.mkdir. It's bug, we need to be sensitive
to only X-mount.mkdir and only if the target directory is missing.

Addresses: https://github.com/karelzak/util-linux/issues/941
Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/libmount/src/context.c b/libmount/src/context.c
index 6c536cc1552f4c4a735b4b8782ed058ab8060d10..91fe8e4bfc1afe185fdb119fd0e8889f4cbf4a82 100644 (file)
--- a/libmount/src/context.c
+++ b/libmount/src/context.c
@@ -1855,49 +1855,48 @@ end:
        return rc;
 }
 
-/* create a mountpoint if X-mount.mkdir[=<mode>] specified */
-static int mkdir_target(const char *tgt, struct libmnt_fs *fs)
+static int is_mkdir_required(const char *tgt, struct libmnt_fs *fs, mode_t *mode, int *rc)
 {
        char *mstr = NULL;
        size_t mstr_sz = 0;
-       mode_t mode = 0;
        struct stat st;
-       int rc;
 
        assert(tgt);
        assert(fs);
+       assert(mode);
+       assert(rc);
+
+       *mode = 0;
+       *rc = 0;
 
        if (mnt_optstr_get_option(fs->user_optstr, "X-mount.mkdir", &mstr, &mstr_sz) != 0 &&
            mnt_optstr_get_option(fs->user_optstr, "x-mount.mkdir", &mstr, &mstr_sz) != 0)      /* obsolete */
                return 0;
 
-       DBG(CXT, ul_debug("mkdir %s (%s) wanted", tgt, mstr));
-
        if (mnt_stat_mountpoint(tgt, &st) == 0)
                return 0;
 
+       DBG(CXT, ul_debug("mkdir %s (%s) wanted", tgt, mstr));
+
        if (mstr && mstr_sz) {
                char *end = NULL;
 
                errno = 0;
-               mode = strtol(mstr, &end, 8);
+               *mode = strtol(mstr, &end, 8);
 
                if (errno || !end || mstr + mstr_sz != end) {
                        DBG(CXT, ul_debug("failed to parse mkdir mode '%s'", mstr));
-                       return -MNT_ERR_MOUNTOPT;
+                       *rc = -MNT_ERR_MOUNTOPT;
+                       return 0;
                }
        }
 
-       if (!mode)
-               mode = S_IRWXU |                        /* 0755 */
+       if (!*mode)
+               *mode = S_IRWXU |                       /* 0755 */
                       S_IRGRP | S_IXGRP |
                       S_IROTH | S_IXOTH;
 
-       rc = mkdir_p(tgt, mode);
-       if (rc)
-               DBG(CXT, ul_debug("mkdir %s failed: %m", tgt));
-
-       return rc;
+       return 1;
 }
 
 int mnt_context_prepare_target(struct libmnt_context *cxt)
@@ -1905,6 +1904,7 @@ int mnt_context_prepare_target(struct libmnt_context *cxt)
        const char *tgt, *prefix;
        int rc = 0;
        struct libmnt_ns *ns_old;
+       mode_t mode = 0;
 
        assert(cxt);
        assert(cxt->fs);
@@ -1946,12 +1946,15 @@ int mnt_context_prepare_target(struct libmnt_context *cxt)
        /* X-mount.mkdir target */
        if (cxt->action == MNT_ACT_MOUNT
            && (cxt->user_mountflags & MNT_MS_XCOMMENT ||
-               cxt->user_mountflags & MNT_MS_XFSTABCOMM)) {
+               cxt->user_mountflags & MNT_MS_XFSTABCOMM)
+           && is_mkdir_required(tgt, cxt->fs, &mode, &rc)) {
 
                /* supported only for root or non-suid mount(8) */
-               if (!mnt_context_is_restricted(cxt))
-                       rc = mkdir_target(tgt, cxt->fs);
-               else
+               if (!mnt_context_is_restricted(cxt)) {
+                       rc = mkdir_p(tgt, mode);
+                       if (rc)
+                               DBG(CXT, ul_debug("mkdir %s failed: %m", tgt));
+               } else
                        rc = -EPERM;
        }
 

diff --git a/sys-utils/mount.8 b/sys-utils/mount.8
index 3e57251ed9f9bce1b6249290ee4390cc374eba46..698b0f0115ac7f41a0056170e0dacdd597c0b124 100644 (file)
--- a/sys-utils/mount.8
+++ b/sys-utils/mount.8
@@ -1306,14 +1306,14 @@ functionality have been extended to keep existing fstab configurations usable
 without a change.
 .TP
 .BR X-mount.mkdir [ = \fImode\fR ]
-Allow to make a target directory (mountpoint).  The optional argument
+Allow to make a target directory (mountpoint) if it does not exit yet.
+The optional argument
 .I mode
 specifies the filesystem access mode used for
 .BR mkdir (2)
 in octal notation.  The default mode is 0755.  This functionality is supported
 only for root users or when mount executed without suid permissions.  The option
-is also supported as x-mount.mkdir, this notation is deprecated for mount.mkdir
-since v2.30.
+is also supported as x-mount.mkdir, this notation is deprecated since v2.30.
 
 .SH "FILESYSTEM-SPECIFIC MOUNT OPTIONS"
 You should consult the respective man page for the filesystem first.