[pseudo][PATCH 5/6] tests: Add setuid permission check

From: Mark Hatle <[email protected]>

Verify that +s permissions are not leaking into real filesystem.

AI-Generated: Implemented with the assistance of github CoPilot (Claude Opus 4.6)

Signed-off-by: Mark Hatle <[email protected]>
Signed-off-by: Mark Hatle <[email protected]>
---
 test/test-setuid-permissions.sh | 58 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)
 create mode 100755 test/test-setuid-permissions.sh

diff --git a/test/test-setuid-permissions.sh b/test/test-setuid-permissions.sh
new file mode 100755
index 0000000..b6fafde
--- /dev/null
+++ b/test/test-setuid-permissions.sh
@@ -0,0 +1,58 @@
+#!/bin/bash
+#
+# SPDX-License-Identifier: LGPL-2.1-only
+#
+set -e
+
+# Verify that setuid/setgid bits tracked by pseudo do not
+# bleed into the real filesystem.
+#
+# Return vals:
+#
+#                 2 - Setuid/setgid bits found on real file
+#                 1 - Unexpected command error
+#                 0 - Pass
+
+mode() {
+	stat -c "%a" "$1"
+}
+
+trap "rm -f testfile" EXIT
+
+test_mode() {
+	local octal_mode="$1"
+	local expected_pseudo="$2"
+	local expected_real="$3"
+
+	chmod $octal_mode testfile
+
+	# Under pseudo, verify mode is as requested
+	local pseudo_mode=$(mode testfile)
+	if [ "$pseudo_mode" != "$expected_pseudo" ]; then
+		echo "FAIL: pseudo mode $pseudo_mode != expected $expected_pseudo (chmod $octal_mode)"
+		exit 1
+	fi
+
+	# Check without pseudo - real file must NOT have setuid/setgid
+	local real_mode=$(PSEUDO_DISABLED=1 stat -c "%a" testfile)
+	if [ "$real_mode" != "$expected_real" ]; then
+		echo "FAIL: real mode $real_mode != expected $expected_real (chmod $octal_mode)"
+		exit 2
+	fi
+}
+
+touch testfile
+
+# Test setuid only (4755)
+test_mode 4755 4755 755
+
+# Test setgid only (2755)
+test_mode 2755 2755 755
+
+# Test setuid + setgid (6755)
+test_mode 6755 6755 755
+
+# Test setuid + setgid + other base perms (6644)
+test_mode 6644 6644 644
+
+exit 0
-- 
1.8.3.1