[LTP] [PATCH v3 6/8] fs/acl: Add symlink ACL operations test
Sachin Sant
sachinp@linux.ibm.com
Wed Jun 3 16:01:45 CEST 2026
Add acl_link01 test to verify that ACL operations on symlinks
follow the symlink to the target file. The test validates that
setting and getting ACLs through a symlink path affects the
target file, not the symlink itself.
Test coverage:
- Create regular file and symlink
- Set ACL through symlink path
- Verify ACL was set on target file
- Get ACL through symlink path
- Compare ACLs to ensure they match
Test returns TCONF if ACL is not supported by the filesystem.
Signed-off-by: Sachin Sant <sachinp@linux.ibm.com>
---
V3 changes:
- Updated the test to read the ACL from both TESTSYMLINK
and TESTFILE, and verify the expected entries/permissions match.
- Updated commit message to reflect this change.
- Updated copyright header as per LTP format.
- v2 link https://lore.kernel.org/ltp/20260603065744.47106-1-sachinp@linux.ibm.com/T/#t
V2 changes:
- Updated incorrect TCONF message and description text
- Updated commit message to remove incorrect symlinks wording
- Use reset_test_path_no_chown variant to skip chown step
and removed needs_cmd tag to avoid useradd/userdel dependency
- v1 link https://lore.kernel.org/ltp/20260602121958.27494-1-sachinp@linux.ibm.com/T/#t
V1 changes:
- Use HAVE_LIBACL guards in .c code
- Report TCONF when libacl is not available
- rfc link https://lore.kernel.org/ltp/477836fd-80c8-4168-bfe6-00b374bb2534@linux.ibm.com/T/#t
---
runtest/fs | 1 +
testcases/kernel/fs/acl/.gitignore | 1 +
testcases/kernel/fs/acl/acl_link01.c | 146 +++++++++++++++++++++++++++
3 files changed, 148 insertions(+)
create mode 100644 testcases/kernel/fs/acl/acl_link01.c
diff --git a/runtest/fs b/runtest/fs
index f1eea055b..64deb56e6 100644
--- a/runtest/fs
+++ b/runtest/fs
@@ -94,3 +94,4 @@ acl_mask01 acl_mask01
acl_other01 acl_other01
acl_inherit01 acl_inherit01
acl_file_ops01 acl_file_ops01
+acl_link01 acl_link01
diff --git a/testcases/kernel/fs/acl/.gitignore b/testcases/kernel/fs/acl/.gitignore
index eb4b4a227..4a071d516 100644
--- a/testcases/kernel/fs/acl/.gitignore
+++ b/testcases/kernel/fs/acl/.gitignore
@@ -3,3 +3,4 @@
/acl_other01
/acl_inherit01
/acl_file_ops01
+/acl_link01
diff --git a/testcases/kernel/fs/acl/acl_link01.c b/testcases/kernel/fs/acl/acl_link01.c
new file mode 100644
index 000000000..6615d9b32
--- /dev/null
+++ b/testcases/kernel/fs/acl/acl_link01.c
@@ -0,0 +1,146 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2026 IBM
+ *
+ * Original shell test by Kai Zhao (ltcd3@cn.ibm.com)
+ * Converted to C by Sachin Sant <sachinp@linux.ibm.com>
+ */
+
+/*\
+ * Test ACL operations on symlinks.
+ *
+ * Verify that ACL operations on symlinks follow the symlink to the target
+ * file. When setting or getting ACLs through a symlink path, the operation
+ * should affect the target file, not the symlink itself.
+ *
+ * Note: Some filesystems may not support ACLs on the target file and will
+ * return EOPNOTSUPP, which is treated as TCONF (test not applicable).
+ *
+ * [Algorithm]
+ *
+ * 1. Create a regular file
+ * 2. Create a symlink pointing to the file
+ * 3. Set ACL through the symlink path
+ * 4. Verify the ACL was set on the target file
+ * 5. Get ACL through the symlink path
+ * 6. Verify we can read the ACL through the symlink
+ */
+
+#include "acl_lib.h"
+
+#ifdef HAVE_LIBACL
+
+static void run(void)
+{
+ acl_t acl, target_acl, symlink_acl;
+ int fd = -1;
+ int err;
+
+ tst_res(TINFO, "Testing ACL operations on symlinks");
+ reset_test_path_no_chown();
+
+ fd = SAFE_OPEN(TESTFILE, O_CREAT | O_WRONLY, 0644);
+ SAFE_CLOSE(fd);
+
+ SAFE_SYMLINK("testfile", TESTSYMLINK);
+
+ acl = acl_init(3);
+ if (!acl) {
+ cleanup_testfile();
+ tst_brk(TBROK | TERRNO, "acl_init failed");
+ }
+
+ add_acl_entry(acl, ACL_USER_OBJ, ACL_READ | ACL_WRITE);
+ add_acl_entry(acl, ACL_GROUP_OBJ, ACL_READ);
+ add_acl_entry(acl, ACL_OTHER, ACL_READ);
+
+ err = acl_set_file(TESTSYMLINK, ACL_TYPE_ACCESS, acl);
+ if (err == -1) {
+ safe_acl_free(acl);
+ if (unlink(TESTSYMLINK) == -1)
+ tst_res(TWARN | TERRNO, "unlink symlink failed");
+ cleanup_testfile();
+ if (errno == EOPNOTSUPP) {
+ tst_res(TCONF,
+ "ACL not supported by this filesystem");
+ return;
+ }
+ tst_brk(TBROK | TERRNO, "acl_set_file on symlink failed");
+ }
+
+ safe_acl_free(acl);
+
+ target_acl = acl_get_file(TESTFILE, ACL_TYPE_ACCESS);
+ if (!target_acl) {
+ if (unlink(TESTSYMLINK) == -1)
+ tst_res(TWARN | TERRNO, "unlink symlink failed");
+ cleanup_testfile();
+ tst_brk(TBROK | TERRNO, "acl_get_file on target failed");
+ }
+
+ symlink_acl = acl_get_file(TESTSYMLINK, ACL_TYPE_ACCESS);
+ if (!symlink_acl) {
+ safe_acl_free(target_acl);
+ if (unlink(TESTSYMLINK) == -1)
+ tst_res(TWARN | TERRNO, "unlink symlink failed");
+ cleanup_testfile();
+ tst_brk(TBROK | TERRNO, "acl_get_file on symlink failed");
+ }
+
+ err = acl_cmp(target_acl, symlink_acl);
+ if (err == -1) {
+ safe_acl_free(symlink_acl);
+ safe_acl_free(target_acl);
+ if (unlink(TESTSYMLINK) == -1)
+ tst_res(TWARN | TERRNO, "unlink symlink failed");
+ cleanup_testfile();
+ tst_brk(TBROK | TERRNO, "acl_cmp failed");
+ }
+
+ safe_acl_free(symlink_acl);
+ safe_acl_free(target_acl);
+
+ if (unlink(TESTSYMLINK) == -1)
+ tst_res(TWARN | TERRNO, "unlink symlink failed");
+ cleanup_testfile();
+
+ if (err != 0) {
+ tst_res(TFAIL,
+ "ACL via symlink differs from ACL on target file");
+ return;
+ }
+
+ tst_res(TPASS, "ACL set via symlink was applied to target file");
+}
+
+static void setup(void)
+{
+ reset_test_path_no_chown();
+}
+
+static void cleanup(void)
+{
+ cleanup_test_paths();
+}
+
+static struct tst_test test = {
+ .test_all = run,
+ .setup = setup,
+ .cleanup = cleanup,
+ .needs_root = 1,
+ .mount_device = 1,
+ .mntpoint = MNTPOINT,
+ .forks_child = 1,
+ .filesystems = (struct tst_fs[]) {
+ {.type = "ext2", .mnt_data = "acl"},
+ {.type = "ext3", .mnt_data = "acl"},
+ {.type = "ext4", .mnt_data = "acl"},
+ {.type = "xfs"},
+ {.type = "btrfs"},
+ {}
+ }
+};
+
+#else
+TST_TEST_TCONF("libacl or ACL headers are not available");
+#endif
--
2.39.1
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