Merge branch 'add TCP_BPF_SOCK_OPS_CB_FLAGS to bpf_*sockopt()'

Alan Maguire says:

====================
As previously discussed here [1], long-lived sockets can miss
a chance to set additional callbacks if a sock ops program
was not attached early in their lifetime.  Adding support
to bpf_setsockopt() to set callback flags (and bpf_getsockopt()
to retrieve them) provides other opportunities to enable callbacks,
either directly via a cgroup/setsockopt intercepted setsockopt()
or via a socket iterator.

Patch 1 adds bpf_[get|set]sockopt() support; patch 2 adds testing
for it via a sockops programs, along with verification via a
cgroup/getsockopt program.

Changes since v1 [2]:

- Removed unneeded READ_ONCE() (Martin, patch 1)
- Reworked sockopt test to leave existing tests undisturbed while adding
  test_nonstandard_opt() test to cover the TCP_BPF_SOCK_OPS_CB_FLAGS
  case; test verifies that value set via bpf_setsockopt() is what we
  expect via a call to getsockopt() which is caught by a
  cgroup/getsockopt program to provide the flags value (Martin, patch 2)
- Removed unneeded iterator test (Martin)

[1] https://lore.kernel.org/bpf/f42f157b-6e52-dd4d-3d97-9b86c84c0b00@oracle.com/
[2] https://lore.kernel.org/bpf/20240802152929.2695863-1-alan.maguire@oracle.com/
====================

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

1 files changed, 47 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/setget_sockopt.c b/tools/testing/selftests/bpf/prog_tests/setget_sockopt.c
index 7d4a9b3d3722..e12255121c15 100644
--- a/tools/testing/selftests/bpf/prog_tests/setget_sockopt.c
+++ b/tools/testing/selftests/bpf/prog_tests/setget_sockopt.c
@@ -154,6 +154,51 @@ err_out:
 	close(sfd);
 }
 
+static void test_nonstandard_opt(int family)
+{
+	struct setget_sockopt__bss *bss = skel->bss;
+	struct bpf_link *getsockopt_link = NULL;
+	int sfd = -1, fd = -1, cfd = -1, flags;
+	socklen_t flagslen = sizeof(flags);
+
+	memset(bss, 0, sizeof(*bss));
+
+	sfd = start_server(family, SOCK_STREAM,
+			   family == AF_INET6 ? addr6_str : addr4_str, 0, 0);
+	if (!ASSERT_GE(sfd, 0, "start_server"))
+		return;
+
+	fd = connect_to_fd(sfd, 0);
+	if (!ASSERT_GE(fd, 0, "connect_to_fd_server"))
+		goto err_out;
+
+	/* cgroup/getsockopt prog will intercept getsockopt() below and
+	 * retrieve the tcp socket bpf_sock_ops_cb_flags value for the
+	 * accept()ed socket; this was set earlier in the passive established
+	 * callback for the accept()ed socket via bpf_setsockopt().
+	 */
+	getsockopt_link = bpf_program__attach_cgroup(skel->progs._getsockopt, cg_fd);
+	if (!ASSERT_OK_PTR(getsockopt_link, "getsockopt prog"))
+		goto err_out;
+
+	cfd = accept(sfd, NULL, 0);
+	if (!ASSERT_GE(cfd, 0, "accept"))
+		goto err_out;
+
+	if (!ASSERT_OK(getsockopt(cfd, SOL_TCP, TCP_BPF_SOCK_OPS_CB_FLAGS, &flags, &flagslen),
+		       "getsockopt_flags"))
+		goto err_out;
+	ASSERT_EQ(flags & BPF_SOCK_OPS_STATE_CB_FLAG, BPF_SOCK_OPS_STATE_CB_FLAG,
+		  "cb_flags_set");
+err_out:
+	close(sfd);
+	if (fd != -1)
+		close(fd);
+	if (cfd != -1)
+		close(cfd);
+	bpf_link__destroy(getsockopt_link);
+}
+
 void test_setget_sockopt(void)
 {
 	cg_fd = test__join_cgroup(CG_NAME);
@@ -191,6 +236,8 @@ void test_setget_sockopt(void)
 	test_udp(AF_INET);
 	test_ktls(AF_INET6);
 	test_ktls(AF_INET);
+	test_nonstandard_opt(AF_INET);
+	test_nonstandard_opt(AF_INET6);
 
 done:
 	setget_sockopt__destroy(skel);