mount: make NAME=value tags usable for non-root

The libmount does not care if we set source or target, it's able to
swap it, but the mount.c function sanitize_paths() does not work as
expected if we set NAME=value as target. It means that

 $ mount LABEL=foo

does not work for non-root users (since 51e3530cdcb1d4f3ab91ae953ebc5adcdc5f9239, v2.24).

This patch also checks if source or target is specified more
than once.

Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/sys-utils/mount.c b/sys-utils/mount.c
index fa1ce15c313dbcc631f1bcf1bf29bfa4d9e4d9d8..ed814ca49e7ea000c003d7b4a391934989e2ea5f 100644 (file)
--- a/sys-utils/mount.c
+++ b/sys-utils/mount.c
@@ -1030,25 +1030,42 @@ int main(int argc, char **argv)
                                 mnt_context_get_target(cxt))) {
                /*
                 * B) mount -L|-U|--source|--target
+                *
+                * non-root may specify source *or* target, but not both
                 */
                if (mnt_context_is_restricted(cxt) &&
                    mnt_context_get_source(cxt) &&
                    mnt_context_get_target(cxt))
                        exit_non_root(NULL);
 
-       } else if (argc == 1) {
+       } else if (argc == 1 && (!mnt_context_get_source(cxt) ||
+                                !mnt_context_get_target(cxt))) {
                /*
                 * C) mount [-L|-U|--source] <target>
+                *    mount [--target <dir>] <source>
                 *    mount <source|target>
                 *
                 * non-root may specify source *or* target, but not both
+                *
+                * It does not matter for libmount if we set source or target
+                * here (the library is able to swap it), but it matters for
+                * sanitize_paths().
                 */
+               int istag = mnt_tag_is_valid(argv[0]);
+
+               if (istag && mnt_context_get_source(cxt))
+                       /* -L, -U or --source together with LABEL= or UUID= */
+                       errx(MOUNT_EX_USAGE, _("source specified more than once"));
+               else if (istag || mnt_context_get_target(cxt))
+                       mnt_context_set_source(cxt, argv[0]);
+               else
+                       mnt_context_set_target(cxt, argv[0]);
+
                if (mnt_context_is_restricted(cxt) &&
-                   mnt_context_get_source(cxt))
+                   mnt_context_get_source(cxt) &&
+                   mnt_context_get_target(cxt))
                        exit_non_root(NULL);
 
-               mnt_context_set_target(cxt, argv[0]);
-
        } else if (argc == 2 && !mnt_context_get_source(cxt)
                             && !mnt_context_get_target(cxt)) {
                /*
@@ -1056,6 +1073,7 @@ int main(int argc, char **argv)
                 */
                if (mnt_context_is_restricted(cxt))
                        exit_non_root(NULL);
+
                mnt_context_set_source(cxt, argv[0]);
                mnt_context_set_target(cxt, argv[1]);