Re-apply path sanitizer, as mount(8) still mangles it

Prior to util-linux 2.36.2, if a file or directory in the
current working directory was named 'dataset' then mount(8)
would prepend the current working directory to the dataset.

Eventually, we should be able to drop this workaround.

Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Sterling Jensen <[email protected]>
Closes openzfs#11295 
Closes openzfs#11462

Author: sterlingjensen

cmd/mount_zfs/mount_zfs.c

@@ -50,6 +50,21 @@ libzfs_handle_t *g_zfs;
 static void
 parse_dataset(const char *target, char **dataset)
 {
+	/*
+	 * Prior to util-linux 2.36.2, if a file or directory in the
+	 * current working directory was named 'dataset' then mount(8)
+	 * would prepend the current working directory to the dataset.
+	 * Check for it and strip the prepended path when it is added.
+	 */
+	char cwd[PATH_MAX];
+	if (getcwd(cwd, PATH_MAX) == NULL) {
+		perror("getcwd");
+		return;
+	}
+	int len = strlen(cwd);
+	if (strncmp(cwd, target, len) == 0)
+		target += len;
+
 	/* Assume pool/dataset is more likely */
 	strlcpy(*dataset, target, PATH_MAX);
 

tests/zfs-tests/tests/functional/cli_root/zfs_mount/zfs_mount_013_pos.ksh

@@ -32,7 +32,9 @@ typeset -r fs=$TESTPOOL/$TESTFS
 function cleanup
 {
 	cd $STF_SUITE
-	[[ -d $TESTDIR/$$ ]] && (rm -rf $TESTDIR/$$ || log_fail)
+	if [[ -d $TESTDIR/$$ ]]; then
+		log_must rm -rf $TESTDIR/$$
+	fi
 	mounted && zfs $mountcmd $TESTPOOL
 	return 0
 }
@@ -50,13 +52,25 @@ force_unmount $fs
 
 log_note "Verify mount(8) does not canonicalize before calling helper"
 # Canonicalization is confused by files in PWD matching [device|mountpoint]
-mkdir -p $TESTDIR/$$/$TESTPOOL && cd $TESTDIR/$$ || log_fail
+log_must mkdir -p $TESTDIR/$$/$TESTPOOL
+log_must cd $TESTDIR/$$
 # The env flag directs zfs to exec /bin/mount, which then calls helper
 log_must eval ZFS_MOUNT_HELPER=1 zfs $mountcmd -v $TESTPOOL
 # mount (2.35.2) still suffers from a cosmetic PWD prefix bug
 log_must mounted $TESTPOOL
 force_unmount $TESTPOOL
 
+log_note "Verify CWD prefix filter <dataset> <path>"
+log_must cd /
+log_must zfs set mountpoint=legacy $TESTPOOL
+log_must mkdir -p $mntpoint
+log_must mount -t zfs $TESTPOOL $mntpoint
+log_must ismounted $TESTPOOL
+log_must umount $mntpoint
+log_must zfs set mountpoint=$mntpoint $TESTPOOL
+log_must cd -
+force_unmount $TESTPOOL
+
 log_note "Verify '-f <dataset> <path>' fakemount"
 log_must $helper -f $fs $mntpoint
 log_mustnot ismounted $fs
@@ -75,4 +89,4 @@ log_note "Verify '<device> <path>'"
 log_must $helper ${vdevs[0]} $mntpoint
 log_must mounted $mntpoint
 
-log_pass "zfs mount helper correctly handles both device and pool strings"
+log_pass "zfs mount helper correctly handles both device and pool strings"