From 8ca2a1eeadf09862190b2810697702d803ceef2d Mon Sep 17 00:00:00 2001 From: Jiayuan Chen Date: Mon, 18 Nov 2024 11:09:09 +0800 Subject: [PATCH 1/2] bpf: fix recursive lock when verdict program return SK_PASS When the stream_verdict program returns SK_PASS, it places the received skb into its own receive queue, but a recursive lock eventually occurs, leading to an operating system deadlock. This issue has been present since v6.9. ''' sk_psock_strp_data_ready write_lock_bh(&sk->sk_callback_lock) strp_data_ready strp_read_sock read_sock -> tcp_read_sock strp_recv cb.rcv_msg -> sk_psock_strp_read # now stream_verdict return SK_PASS without peer sock assign __SK_PASS = sk_psock_map_verd(SK_PASS, NULL) sk_psock_verdict_apply sk_psock_skb_ingress_self sk_psock_skb_ingress_enqueue sk_psock_data_ready read_lock_bh(&sk->sk_callback_lock) <= dead lock ''' This topic has been discussed before, but it has not been fixed. Previous discussion: https://lore.kernel.org/all/6684a5864ec86_403d20898@john.notmuch Fixes: 6648e613226e ("bpf, skmsg: Fix NULL pointer dereference in sk_psock_skb_ingress_enqueue") Reported-by: Vincent Whitchurch Signed-off-by: Jiayuan Chen Signed-off-by: John Fastabend Acked-by: Martin KaFai Lau Link: https://patch.msgid.link/20241118030910.36230-2-mrpre@163.com Signed-off-by: Jakub Kicinski --- net/core/skmsg.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/core/skmsg.c b/net/core/skmsg.c index b1dcbd3be89e..e90fbab703b2 100644 --- a/net/core/skmsg.c +++ b/net/core/skmsg.c @@ -1117,9 +1117,9 @@ static void sk_psock_strp_data_ready(struct sock *sk) if (tls_sw_has_ctx_rx(sk)) { psock->saved_data_ready(sk); } else { - write_lock_bh(&sk->sk_callback_lock); + read_lock_bh(&sk->sk_callback_lock); strp_data_ready(&psock->strp); - write_unlock_bh(&sk->sk_callback_lock); + read_unlock_bh(&sk->sk_callback_lock); } } rcu_read_unlock(); From 0c4d5cb9a1c3583b61df199a51eccebe759e3c18 Mon Sep 17 00:00:00 2001 From: Jiayuan Chen Date: Mon, 18 Nov 2024 11:09:10 +0800 Subject: [PATCH 2/2] selftests/bpf: Add some tests with sockmap SK_PASS Add a new tests in sockmap_basic.c to test SK_PASS for sockmap Signed-off-by: Jiayuan Chen Acked-by: Martin KaFai Lau Link: https://patch.msgid.link/20241118030910.36230-3-mrpre@163.com Signed-off-by: Jakub Kicinski --- .../selftests/bpf/prog_tests/sockmap_basic.c | 54 +++++++++++++++++++ 1 file changed, 54 insertions(+) diff --git a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c index 82bfb266741c..a2041f8e32eb 100644 --- a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c +++ b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c @@ -501,6 +501,58 @@ static void test_sockmap_skb_verdict_shutdown(void) test_sockmap_pass_prog__destroy(skel); } +static void test_sockmap_stream_pass(void) +{ + int zero = 0, sent, recvd; + int verdict, parser; + int err, map; + int c = -1, p = -1; + struct test_sockmap_pass_prog *pass = NULL; + char snd[256] = "0123456789"; + char rcv[256] = "0"; + + pass = test_sockmap_pass_prog__open_and_load(); + verdict = bpf_program__fd(pass->progs.prog_skb_verdict); + parser = bpf_program__fd(pass->progs.prog_skb_parser); + map = bpf_map__fd(pass->maps.sock_map_rx); + + err = bpf_prog_attach(parser, map, BPF_SK_SKB_STREAM_PARSER, 0); + if (!ASSERT_OK(err, "bpf_prog_attach stream parser")) + goto out; + + err = bpf_prog_attach(verdict, map, BPF_SK_SKB_STREAM_VERDICT, 0); + if (!ASSERT_OK(err, "bpf_prog_attach stream verdict")) + goto out; + + err = create_pair(AF_INET, SOCK_STREAM, &c, &p); + if (err) + goto out; + + /* sk_data_ready of 'p' will be replaced by strparser handler */ + err = bpf_map_update_elem(map, &zero, &p, BPF_NOEXIST); + if (!ASSERT_OK(err, "bpf_map_update_elem(p)")) + goto out_close; + + /* + * as 'prog_skb_parser' return the original skb len and + * 'prog_skb_verdict' return SK_PASS, the kernel will just + * pass it through to original socket 'p' + */ + sent = xsend(c, snd, sizeof(snd), 0); + ASSERT_EQ(sent, sizeof(snd), "xsend(c)"); + + recvd = recv_timeout(p, rcv, sizeof(rcv), SOCK_NONBLOCK, + IO_TIMEOUT_SEC); + ASSERT_EQ(recvd, sizeof(rcv), "recv_timeout(p)"); + +out_close: + close(c); + close(p); + +out: + test_sockmap_pass_prog__destroy(pass); +} + static void test_sockmap_skb_verdict_fionread(bool pass_prog) { int err, map, verdict, c0 = -1, c1 = -1, p0 = -1, p1 = -1; @@ -923,6 +975,8 @@ void test_sockmap_basic(void) test_sockmap_progs_query(BPF_SK_SKB_VERDICT); if (test__start_subtest("sockmap skb_verdict shutdown")) test_sockmap_skb_verdict_shutdown(); + if (test__start_subtest("sockmap stream parser and verdict pass")) + test_sockmap_stream_pass(); if (test__start_subtest("sockmap skb_verdict fionread")) test_sockmap_skb_verdict_fionread(true); if (test__start_subtest("sockmap skb_verdict fionread on drop"))