Commit 3daf8e70 authored by Stanislav Fomichev's avatar Stanislav Fomichev Committed by Daniel Borkmann
Browse files

selftests: bpf: add selftest for __sk_buff context in BPF_PROG_TEST_RUN 



Simple test that sets cb to {1,2,3,4,5} and priority to 6, runs bpf
program that fails if cb is not what we expect and increments cb[i] and
priority. When the test finishes, we check that cb is now {2,3,4,5,6}
and priority is 7.

We also test the sanity checks:
* ctx_in is provided, but ctx_size_in is zero (same for
  ctx_out/ctx_size_out)
* unexpected non-zero fields in __sk_buff return EINVAL

Signed-off-by: default avatarStanislav Fomichev <sdf@google.com>
Acked-by: default avatarMartin KaFai Lau <kafai@fb.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent 5e903c65

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

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// SPDX-License-Identifier: GPL-2.0

#include <test_progs.h>



void test_skb_ctx(void)

{

	struct __sk_buff skb = {

		.cb[0] = 1,

		.cb[1] = 2,

		.cb[2] = 3,

		.cb[3] = 4,

		.cb[4] = 5,

		.priority = 6,

	};

	struct bpf_prog_test_run_attr tattr = {

		.data_in = &pkt_v4,

		.data_size_in = sizeof(pkt_v4),

		.ctx_in = &skb,

		.ctx_size_in = sizeof(skb),

		.ctx_out = &skb,

		.ctx_size_out = sizeof(skb),

	};

	struct bpf_object *obj;

	int err;

	int i;



	err = bpf_prog_load("./test_skb_ctx.o", BPF_PROG_TYPE_SCHED_CLS, &obj,

			    &tattr.prog_fd);

	if (CHECK_ATTR(err, "load", "err %d errno %d\n", err, errno))

		return;



	/* ctx_in != NULL, ctx_size_in == 0 */



	tattr.ctx_size_in = 0;

	err = bpf_prog_test_run_xattr(&tattr);

	CHECK_ATTR(err == 0, "ctx_size_in", "err %d errno %d\n", err, errno);

	tattr.ctx_size_in = sizeof(skb);



	/* ctx_out != NULL, ctx_size_out == 0 */



	tattr.ctx_size_out = 0;

	err = bpf_prog_test_run_xattr(&tattr);

	CHECK_ATTR(err == 0, "ctx_size_out", "err %d errno %d\n", err, errno);

	tattr.ctx_size_out = sizeof(skb);



	/* non-zero [len, tc_index] fields should be rejected*/



	skb.len = 1;

	err = bpf_prog_test_run_xattr(&tattr);

	CHECK_ATTR(err == 0, "len", "err %d errno %d\n", err, errno);

	skb.len = 0;



	skb.tc_index = 1;

	err = bpf_prog_test_run_xattr(&tattr);

	CHECK_ATTR(err == 0, "tc_index", "err %d errno %d\n", err, errno);

	skb.tc_index = 0;



	/* non-zero [hash, sk] fields should be rejected */



	skb.hash = 1;

	err = bpf_prog_test_run_xattr(&tattr);

	CHECK_ATTR(err == 0, "hash", "err %d errno %d\n", err, errno);

	skb.hash = 0;



	skb.sk = (struct bpf_sock *)1;

	err = bpf_prog_test_run_xattr(&tattr);

	CHECK_ATTR(err == 0, "sk", "err %d errno %d\n", err, errno);

	skb.sk = 0;



	err = bpf_prog_test_run_xattr(&tattr);

	CHECK_ATTR(err != 0 || tattr.retval,

		   "run",

		   "err %d errno %d retval %d\n",

		   err, errno, tattr.retval);



	CHECK_ATTR(tattr.ctx_size_out != sizeof(skb),

		   "ctx_size_out",

		   "incorrect output size, want %lu have %u\n",

		   sizeof(skb), tattr.ctx_size_out);



	for (i = 0; i < 5; i++)

		CHECK_ATTR(skb.cb[i] != i + 2,

			   "ctx_out_cb",

			   "skb->cb[i] == %d, expected %d\n",

			   skb.cb[i], i + 2);

	CHECK_ATTR(skb.priority != 7,

		   "ctx_out_priority",

		   "skb->priority == %d, expected %d\n",

		   skb.priority, 7);

}

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

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// SPDX-License-Identifier: GPL-2.0



#include <linux/bpf.h>

#include "bpf_helpers.h"



int _version SEC("version") = 1;

char _license[] SEC("license") = "GPL";



SEC("skb_ctx")

int process(struct __sk_buff *skb)

{

	#pragma clang loop unroll(full)

	for (int i = 0; i < 5; i++) {

		if (skb->cb[i] != i + 1)

			return 1;

		skb->cb[i]++;

	}

	skb->priority++;



	return 0;

}

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