From 03f036cbccdd8699f5fe8540ef317595a35bceb8 Mon Sep 17 00:00:00 2001
From: sterlingjensen <5555776+sterlingjensen@users.noreply.github.com>
Date: Tue, 19 Jan 2021 13:57:31 -0600
Subject: [PATCH] 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 <behlendorf1@llnl.gov>
Signed-off-by: Sterling Jensen <sterlingjensen@users.noreply.github.com>
Closes #11295
Closes #11462
---
 cmd/mount_zfs/mount_zfs.c                     | 15 ++++++++++++++
 .../cli_root/zfs_mount/zfs_mount_013_pos.ksh  | 20 ++++++++++++++++---
 2 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/cmd/mount_zfs/mount_zfs.c b/cmd/mount_zfs/mount_zfs.c
index ca39d22847..5196c3e5cb 100644
--- a/cmd/mount_zfs/mount_zfs.c
+++ b/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);
 
diff --git a/tests/zfs-tests/tests/functional/cli_root/zfs_mount/zfs_mount_013_pos.ksh b/tests/zfs-tests/tests/functional/cli_root/zfs_mount/zfs_mount_013_pos.ksh
index 810a69470d..e6a4be1577 100755
--- a/tests/zfs-tests/tests/functional/cli_root/zfs_mount/zfs_mount_013_pos.ksh
+++ b/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"
\ No newline at end of file
+log_pass "zfs mount helper correctly handles both device and pool strings"