[PATCH v4 03/19] selftests/liveupdate: Add tests for preserve and retrieve user argument

[David Matlack <dmatlack@google.com>]

From: Pasha Tatashin <pasha.tatashin@soleen.com>

Verify the user argument support in LIVEUPDATE_SESSION_PRESERVE_FD and
LIVEUPDATE_SESSION_RETRIEVE_FD. Add luo_session_preserve_fd_arg() and
luo_session_retrieve_fd_arg() helpers to libliveupdate so tests can pass
a handler-specific argument.

Add a preserve_memfd_with_arg test case to verify that memfd
preservation rejects a non-zero argument with -EOPNOTSUPP, accepts an
explicit zero argument, and remains compatible with callers passing the
legacy struct size up to the token field.

Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org>
---
 .../liveupdate/lib/include/libliveupdate.h    |  3 ++
 .../selftests/liveupdate/lib/lu_utils.c       | 17 ++++++-
 .../testing/selftests/liveupdate/liveupdate.c | 44 +++++++++++++++++++
 3 files changed, 62 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/liveupdate/lib/include/libliveupdate.h b/tools/testing/selftests/liveupdate/lib/include/libliveupdate.h
index fa07fed08364..cd1d843a0d3d 100644
--- a/tools/testing/selftests/liveupdate/lib/include/libliveupdate.h
+++ b/tools/testing/selftests/liveupdate/lib/include/libliveupdate.h
@@ -29,7 +29,10 @@ int luo_get_session_name(int session_fd, char *name, size_t name_len);
 
 int luo_ensure_nofile_limit(long min_limit);
 int luo_session_preserve_fd(int session_fd, int fd, __u64 token);
+int luo_session_preserve_fd_arg(int session_fd, int fd, __u64 token,
+				__u64 user_arg);
 int luo_session_retrieve_fd(int session_fd, __u64 token);
+int luo_session_retrieve_fd_arg(int session_fd, __u64 token, __u64 user_arg);
 
 int create_and_preserve_memfd(int session_fd, int token, const char *data);
 int restore_and_verify_memfd(int session_fd, int token, const char *expected_data);
diff --git a/tools/testing/selftests/liveupdate/lib/lu_utils.c b/tools/testing/selftests/liveupdate/lib/lu_utils.c
index 74d41115c281..db7a90b002cb 100644
--- a/tools/testing/selftests/liveupdate/lib/lu_utils.c
+++ b/tools/testing/selftests/liveupdate/lib/lu_utils.c
@@ -79,12 +79,14 @@ int luo_retrieve_session(int luo_fd, const char *name)
 	return arg.fd;
 }
 
-int luo_session_preserve_fd(int session_fd, int fd, __u64 token)
+int luo_session_preserve_fd_arg(int session_fd, int fd, __u64 token,
+				__u64 user_arg)
 {
 	struct liveupdate_session_preserve_fd arg = {
 		.size = sizeof(arg),
 		.fd = fd,
 		.token = token,
+		.arg = user_arg,
 	};
 
 	if (ioctl(session_fd, LIVEUPDATE_SESSION_PRESERVE_FD, &arg))
@@ -93,11 +95,17 @@ int luo_session_preserve_fd(int session_fd, int fd, __u64 token)
 	return 0;
 }
 
-int luo_session_retrieve_fd(int session_fd, __u64 token)
+int luo_session_preserve_fd(int session_fd, int fd, __u64 token)
+{
+	return luo_session_preserve_fd_arg(session_fd, fd, token, 0);
+}
+
+int luo_session_retrieve_fd_arg(int session_fd, __u64 token, __u64 user_arg)
 {
 	struct liveupdate_session_retrieve_fd arg = {
 		.size = sizeof(arg),
 		.token = token,
+		.arg = user_arg,
 	};
 
 	if (ioctl(session_fd, LIVEUPDATE_SESSION_RETRIEVE_FD, &arg))
@@ -106,6 +114,11 @@ int luo_session_retrieve_fd(int session_fd, __u64 token)
 	return arg.fd;
 }
 
+int luo_session_retrieve_fd(int session_fd, __u64 token)
+{
+	return luo_session_retrieve_fd_arg(session_fd, token, 0);
+}
+
 /* Helper function to get a session name via ioctl. */
 int luo_get_session_name(int session_fd, char *name, size_t name_len)
 {
diff --git a/tools/testing/selftests/liveupdate/liveupdate.c b/tools/testing/selftests/liveupdate/liveupdate.c
index 2dedd5fc2534..4c4272167635 100644
--- a/tools/testing/selftests/liveupdate/liveupdate.c
+++ b/tools/testing/selftests/liveupdate/liveupdate.c
@@ -20,6 +20,7 @@
 
 #include <errno.h>
 #include <fcntl.h>
+#include <stddef.h>
 #include <string.h>
 #include <sys/ioctl.h>
 #include <unistd.h>
@@ -530,4 +531,47 @@ TEST_F(liveupdate_device, preserve_many_files)
 	ASSERT_EQ(close(session_fd), 0);
 }
 
+/*
+ * Test Case: Preserve MemFD with User Argument
+ *
+ * Verifies that passing a non-zero user argument to memfd preservation fails
+ * with -EOPNOTSUPP, while passing a zero argument or using the minimum struct
+ * size without the arg field succeeds.
+ */
+TEST_F(liveupdate_device, preserve_memfd_with_arg)
+{
+	struct liveupdate_session_preserve_fd min_arg = {};
+	int session_fd, mem_fd1, mem_fd2;
+
+	self->fd1 = open(LIVEUPDATE_DEV, O_RDWR);
+	if (self->fd1 < 0 && errno == ENOENT)
+		SKIP(return, "%s does not exist", LIVEUPDATE_DEV);
+	ASSERT_GE(self->fd1, 0);
+
+	session_fd = luo_create_session(self->fd1, "preserve-arg-test");
+	ASSERT_GE(session_fd, 0);
+
+	mem_fd1 = memfd_create("arg-memfd-1", 0);
+	ASSERT_GE(mem_fd1, 0);
+
+	/* Non-zero arg is not supported by memfd handler */
+	EXPECT_EQ(luo_session_preserve_fd_arg(session_fd, mem_fd1, 0x1111, 1),
+		  -EOPNOTSUPP);
+
+	/* Legacy struct size (up to token) should zero-fill arg and succeed */
+	min_arg.size = offsetof(struct liveupdate_session_preserve_fd, arg);
+	min_arg.fd = mem_fd1;
+	min_arg.token = 0x1111;
+	ASSERT_EQ(ioctl(session_fd, LIVEUPDATE_SESSION_PRESERVE_FD, &min_arg), 0);
+
+	/* Explicit zero arg with full struct size should also succeed */
+	mem_fd2 = memfd_create("arg-memfd-2", 0);
+	ASSERT_GE(mem_fd2, 0);
+	ASSERT_EQ(luo_session_preserve_fd_arg(session_fd, mem_fd2, 0x2222, 0), 0);
+
+	ASSERT_EQ(close(session_fd), 0);
+	ASSERT_EQ(close(mem_fd1), 0);
+	ASSERT_EQ(close(mem_fd2), 0);
+}
+
 TEST_HARNESS_MAIN
-- 
2.56.0.542.g3ef89b7020-goog