Commit 6cc73f35 authored by Martin KaFai Lau's avatar Martin KaFai Lau Committed by Alexei Starovoitov
Browse files

selftests/bpf: Test bpf_skb_check_mtu(BPF_MTU_CHK_SEGS) when transport_header is not set 



Add a test to check that bpf_skb_check_mtu(BPF_MTU_CHK_SEGS) is
rejected (-EINVAL) if skb->transport_header is not set. The test
needs to lower the MTU of the loopback device. Thus, take this
opportunity to run the test in a netns by adding "ns_" to the test
name. The "serial_" prefix can then be removed.

Signed-off-by: default avatarMartin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20251112232331.1566074-2-martin.lau@linux.dev


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent d946f3c9

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

+22 −1
Original line number Diff line number Diff line
@@ -153,6 +153,26 @@ static void test_check_mtu_run_tc(struct test_check_mtu *skel, 
	ASSERT_EQ(mtu_result, mtu_expect, "MTU-compare-user");

}



static void test_chk_segs_flag(struct test_check_mtu *skel, __u32 mtu)

{

	int err, prog_fd = bpf_program__fd(skel->progs.tc_chk_segs_flag);

	struct __sk_buff skb = {

		.gso_size = 10,

	};

	LIBBPF_OPTS(bpf_test_run_opts, topts,

		    .data_in = &pkt_v4,

		    .data_size_in = sizeof(pkt_v4),

		    .ctx_in = &skb,

		    .ctx_size_in = sizeof(skb),

	);



	/* Lower the mtu to test the BPF_MTU_CHK_SEGS */

	SYS_NOFAIL("ip link set dev lo mtu 10");

	err = bpf_prog_test_run_opts(prog_fd, &topts);

	SYS_NOFAIL("ip link set dev lo mtu %u", mtu);

	ASSERT_OK(err, "test_run");

	ASSERT_EQ(topts.retval, BPF_OK, "retval");

}



static void test_check_mtu_tc(__u32 mtu, __u32 ifindex)

{
@@ -177,11 +197,12 @@ static void test_check_mtu_tc(__u32 mtu, __u32 ifindex) 
	test_check_mtu_run_tc(skel, skel->progs.tc_minus_delta, mtu);

	test_check_mtu_run_tc(skel, skel->progs.tc_input_len, mtu);

	test_check_mtu_run_tc(skel, skel->progs.tc_input_len_exceed, mtu);

	test_chk_segs_flag(skel, mtu);

cleanup:

	test_check_mtu__destroy(skel);

}



void serial_test_check_mtu(void)

void test_ns_check_mtu(void)

{

	int mtu_lo;

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

+12 −0
Original line number Diff line number Diff line
@@ -7,6 +7,7 @@ 


#include <stddef.h>

#include <stdint.h>

#include <errno.h>



char _license[] SEC("license") = "GPL";
@@ -288,3 +289,14 @@ int tc_input_len_exceed(struct __sk_buff *ctx) 
	global_bpf_mtu_xdp = mtu_len;

	return retval;

}



SEC("tc")

int tc_chk_segs_flag(struct __sk_buff *ctx)

{

	__u32 mtu_len = 0;

	int err;



	err = bpf_check_mtu(ctx, GLOBAL_USER_IFINDEX, &mtu_len, 0, BPF_MTU_CHK_SEGS);



	return err == -EINVAL ? BPF_OK : BPF_DROP;

}