Commit 52b6b533 authored by KaFai Wan's avatar KaFai Wan Committed by Martin KaFai Lau
Browse files

selftests/bpf: Test TCP_NODELAY in TCP hdr opt callbacks 



Add a sockops selftest for the TCP_NODELAY restriction in
BPF_SOCK_OPS_HDR_OPT_LEN_CB and BPF_SOCK_OPS_WRITE_HDR_OPT_CB.

With BPF_SOCK_OPS_WRITE_HDR_OPT_CB_FLAG enabled,
bpf_setsockopt(TCP_NODELAY) returns -EOPNOTSUPP from
BPF_SOCK_OPS_HDR_OPT_LEN_CB and BPF_SOCK_OPS_WRITE_HDR_OPT_CB, avoiding
unbounded recursion and kernel stack overflow.

Other cases continue to work as before, including
BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB.

Signed-off-by: default avatarKaFai Wan <kafai.wan@linux.dev>
Signed-off-by: default avatarMartin KaFai Lau <martin.lau@kernel.org>
Reviewed-by: default avatarJiayuan Chen <jiayuan.chen@linux.dev>
Link: https://patch.msgid.link/20260421155804.135786-4-kafai.wan@linux.dev
parent 54377fca

tools/testing/selftests/bpf/prog_tests/tcp_hdr_options.c

+4 −0
Original line number Diff line number Diff line
@@ -507,6 +507,10 @@ static void misc(void) 


	ASSERT_EQ(misc_skel->bss->nr_hwtstamp, 0, "nr_hwtstamp");



	ASSERT_TRUE(misc_skel->bss->nodelay_est_ok, "nodelay_est_ok");

	ASSERT_TRUE(misc_skel->bss->nodelay_hdr_len_reject, "nodelay_hdr_len_reject");

	ASSERT_TRUE(misc_skel->bss->nodelay_write_hdr_reject, "nodelay_write_hdr_reject");



check_linum:

	ASSERT_FALSE(check_error_linum(&sk_fds), "check_error_linum");

	sk_fds_close(&sk_fds);

tools/testing/selftests/bpf/progs/test_misc_tcp_hdr_options.c

+14 −1
Original line number Diff line number Diff line
@@ -29,6 +29,10 @@ unsigned int nr_syn = 0; 
unsigned int nr_fin = 0;

unsigned int nr_hwtstamp = 0;



bool nodelay_est_ok = false;

bool nodelay_hdr_len_reject = false;

bool nodelay_write_hdr_reject = false;



/* Check the header received from the active side */

static int __check_active_hdr_in(struct bpf_sock_ops *skops, bool check_syn)

{
@@ -300,7 +304,7 @@ static int handle_passive_estab(struct bpf_sock_ops *skops) 
SEC("sockops")

int misc_estab(struct bpf_sock_ops *skops)

{

	int true_val = 1;

	int true_val = 1, false_val = 0, ret;



	switch (skops->op) {

	case BPF_SOCK_OPS_TCP_LISTEN_CB:
@@ -316,10 +320,19 @@ int misc_estab(struct bpf_sock_ops *skops) 
	case BPF_SOCK_OPS_PARSE_HDR_OPT_CB:

		return handle_parse_hdr(skops);

	case BPF_SOCK_OPS_HDR_OPT_LEN_CB:

		ret = bpf_setsockopt(skops, SOL_TCP, TCP_NODELAY, &true_val, sizeof(true_val));

		if (ret == -EOPNOTSUPP)

			nodelay_hdr_len_reject = true;

		return handle_hdr_opt_len(skops);

	case BPF_SOCK_OPS_WRITE_HDR_OPT_CB:

		ret = bpf_setsockopt(skops, SOL_TCP, TCP_NODELAY, &true_val, sizeof(true_val));

		if (ret == -EOPNOTSUPP)

			nodelay_write_hdr_reject = true;

		return handle_write_hdr_opt(skops);

	case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB:

		ret = bpf_setsockopt(skops, SOL_TCP, TCP_NODELAY, &false_val, sizeof(false_val));

		if (!ret)

			nodelay_est_ok = true;

		return handle_passive_estab(skops);

	}