netdev - [PATCH bpf v2 3/3] bpf/selftests: Add check for updating XDP bpf

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Date:   Fri,  7 Jan 2022 23:11:15 +0100
From:   Toke Høiland-Jørgensen <toke@...hat.com>
To:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        John Fastabend <john.fastabend@...il.com>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        KP Singh <kpsingh@...nel.org>
Cc:     Toke Høiland-Jørgensen <toke@...hat.com>,
        Shuah Khan <shuah@...nel.org>, netdev@...r.kernel.org,
        bpf@...r.kernel.org
Subject: [PATCH bpf v2 3/3] bpf/selftests: Add check for updating XDP bpf_link with wrong program type

Add a check to the xdp_link selftest that the kernel rejects replacing an
XDP program with a different program type on link update.

v2:
- Split this out into its own patch.

Signed-off-by: Toke Høiland-Jørgensen <toke@...hat.com>
---
 tools/testing/selftests/bpf/prog_tests/xdp_link.c | 5 +++++
 tools/testing/selftests/bpf/progs/test_xdp_link.c | 6 ++++++
 2 files changed, 11 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_link.c b/tools/testing/selftests/bpf/prog_tests/xdp_link.c
index eec0bf83546b..b2b357f8c74c 100644
--- a/tools/testing/selftests/bpf/prog_tests/xdp_link.c
+++ b/tools/testing/selftests/bpf/prog_tests/xdp_link.c
@@ -127,6 +127,11 @@ void serial_test_xdp_link(void)
 	ASSERT_EQ(link_info.prog_id, id1, "link_prog_id");
 	ASSERT_EQ(link_info.xdp.ifindex, IFINDEX_LO, "link_ifindex");
 
+	/* updating program under active BPF link with different type fails */
+	err = bpf_link__update_program(link, skel1->progs.tc_handler);
+	if (!ASSERT_ERR(err, "link_upd_invalid"))
+		goto cleanup;
+
 	err = bpf_link__detach(link);
 	if (!ASSERT_OK(err, "link_detach"))
 		goto cleanup;
diff --git a/tools/testing/selftests/bpf/progs/test_xdp_link.c b/tools/testing/selftests/bpf/progs/test_xdp_link.c
index ee7d6ac0f615..64ff32eaae92 100644
--- a/tools/testing/selftests/bpf/progs/test_xdp_link.c
+++ b/tools/testing/selftests/bpf/progs/test_xdp_link.c
@@ -10,3 +10,9 @@ int xdp_handler(struct xdp_md *xdp)
 {
 	return 0;
 }
+
+SEC("tc")
+int tc_handler(struct __sk_buff *skb)
+{
+	return 0;
+}
-- 
2.34.1