[LTP] [PATCH v3 1/2] fsetxattr02: Adapt test for kernel 7.1.0+ socket xattr support

[Jan Polensky]

Starting with kernel 7.1.0, sockets support extended attributes in the
user.* namespace. This behavior was enabled by dc0876b9846d ("xattr: support
extended attributes on sockets"), which permits user.* xattrs on S_IFSOCK
inodes (previously rejected with -EPERM).

Adapts the test to expect success (exp_err = 0) instead of EPERM when
testing fsetxattr(2) on sockets with kernel 7.1.0+.

Behavior:
- Kernel < 7.1.0: fsetxattr() on socket returns -EPERM (original behavior)
- Kernel >= 7.1.0: fsetxattr() on socket returns 0 (success, new behavior)

Signed-off-by: Jan Polensky <japo@linux.ibm.com>
---
 .../kernel/syscalls/fsetxattr/fsetxattr02.c   | 22 ++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/testcases/kernel/syscalls/fsetxattr/fsetxattr02.c b/testcases/kernel/syscalls/fsetxattr/fsetxattr02.c
index 18490a865871..be6e7f489816 100644
--- a/testcases/kernel/syscalls/fsetxattr/fsetxattr02.c
+++ b/testcases/kernel/syscalls/fsetxattr/fsetxattr02.c
@@ -19,7 +19,10 @@
  * - Set attribute to a block special file, fsetxattr(2) should
  *   return -1 and set errno to EPERM.
  * - Set attribute to a UNIX domain socket, fsetxattr(2) should
- *   return -1 and set errno to EPERM.
+ *   return -1 and set errno to EPERM on kernels < 7.1.0.
+ *   On kernel 7.1.0+ (dc0876b9846d "xattr: support extended 
+ *   attributes on sockets"), returns 0 (success) as sockets now 
+ *   support user.* xattrs.
  */
 
 /*
@@ -62,6 +65,8 @@
 #define BLK      MNTPOINT"/fsetxattr02blk"
 #define SOCK     "fsetxattr02sock"
 
+static bool socket_xattr_supported;
+
 struct test_case {
 	char *fname;
 	int fd;
@@ -73,7 +78,16 @@ struct test_case {
 	int exp_err;
 	int issocket;
 	int needskeyset;
+	void (*fix_errno)(struct test_case *tc);
 };
+
+static void fix_sock(struct test_case *tc)
+{
+	/* dc0876b9846d ("xattr: support extended attributes on sockets") */
+	if (socket_xattr_supported)
+		tc->exp_err = 0;
+}
+
 static struct test_case tc[] = {
 	{			/* case 00, set attr to reg */
 	 .fname = FILENAME,
@@ -139,6 +153,7 @@ static struct test_case tc[] = {
 	 .flags = XATTR_CREATE,
 	 .exp_err = EPERM,
 	 .issocket = 1,
+	 .fix_errno = fix_sock,
 	 },
 };
 
@@ -152,6 +167,9 @@ static void verify_fsetxattr(unsigned int i)
 				XATTR_CREATE);
 	}
 
+	if (tc[i].fix_errno)
+		tc[i].fix_errno(&tc[i]);
+
 	TEST(fsetxattr(tc[i].fd, tc[i].key, tc[i].value, tc[i].size,
 			tc[i].flags));
 
@@ -233,6 +251,8 @@ static void setup(void)
 		SAFE_BIND(tc[i].fd, (const struct sockaddr *) &sun,
 				sizeof(struct sockaddr_un));
 	}
+
+	socket_xattr_supported = (tst_kvercmp(7, 1, 0) >= 0);
 }
 
 static void cleanup(void)
-- 
2.53.0