ZTS/rsend: receive into a '.' or '..' component must fail

Receive a snapshot into $POOL2/. and $POOL2/.. and check that both
are rejected and that a name starting with a dot is still accepted.

Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Christos Longros <[email protected]>
Closes #18975
Closes #19010

tests/runfiles/common.run

@@ -1004,8 +1004,9 @@ tests = ['rootpool_002_neg', 'rootpool_003_neg', 'rootpool_007_pos']
 tags = ['functional', 'rootpool']
 
 [tests/functional/rsend]
-tests = ['recv_dedup', 'recv_dedup_encrypted_zvol', 'rsend_001_pos',
-    'rsend_002_pos', 'rsend_003_pos', 'rsend_004_pos', 'rsend_005_pos',
+tests = ['recv_dedup', 'recv_dedup_encrypted_zvol',
+    'recv_dot_name_neg', 'rsend_001_pos', 'rsend_002_pos',
+    'rsend_003_pos', 'rsend_004_pos', 'rsend_005_pos',
     'rsend_006_pos', 'rsend_007_pos', 'rsend_008_pos', 'rsend_009_pos',
     'rsend_010_pos', 'rsend_011_pos', 'rsend_012_pos', 'rsend_013_pos',
     'rsend_014_pos', 'rsend_016_neg', 'rsend_019_pos', 'rsend_020_pos',

tests/zfs-tests/tests/Makefile.am

@@ -2161,6 +2161,7 @@ nobase_dist_datadir_zfs_tests_tests_SCRIPTS += \
 	functional/rsend/cleanup.ksh \
 	functional/rsend/recv_dedup_encrypted_zvol.ksh \
 	functional/rsend/recv_dedup.ksh \
+	functional/rsend/recv_dot_name_neg.ksh \
 	functional/rsend/recv_validate_001_neg.ksh \
 	functional/rsend/rsend_001_pos.ksh \
 	functional/rsend/rsend_002_pos.ksh \

tests/zfs-tests/tests/functional/rsend/recv_dot_name_neg.ksh

@@ -0,0 +1,54 @@
+#!/bin/ksh -p
+# SPDX-License-Identifier: CDDL-1.0
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# https://opensource.org/license/CDDL-1.0.
+#
+
+#
+# Copyright (c) 2026, Christos Longros. All rights reserved.
+#
+
+. $STF_SUITE/include/libtest.shlib
+. $STF_SUITE/tests/functional/rsend/rsend.kshlib
+
+#
+# Description:
+# Verify that zfs receive rejects a target dataset that ends in a '.'
+# or '..' component.  The received snapshot name is checked as a whole,
+# so the component ends at '@' rather than at the end of the name.
+#
+# Strategy:
+# 1. Receive a snapshot into $POOL2/. and $POOL2/.. and verify both fail
+# 2. Verify that neither dataset was created
+# 3. Verify that $POOL2 can still be listed recursively
+# 4. Receive the same snapshot into $POOL2/.dot and verify it succeeds
+#
+
+verify_runnable "both"
+
+function cleanup
+{
+	cleanup_pool $POOL2
+}
+log_onexit cleanup
+
+log_assert "zfs receive rejects a target ending in a '.' or '..' component"
+
+typeset name
+for name in "$POOL2/." "$POOL2/.."; do
+	log_mustnot eval "zfs send $POOL/$FS@final | zfs receive $name"
+	log_mustnot eval "zfs list -H -o name -d 1 $POOL2 | grep -qxF '$name'"
+done
+log_must zfs list -r $POOL2
+
+log_must eval "zfs send $POOL/$FS@final | zfs receive $POOL2/.dot"
+log_must datasetexists $POOL2/.dot
+
+log_pass "zfs receive rejects a target ending in a '.' or '..' component"