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Commit 0367d0a2 authored by Nikita V. Shirokov's avatar Nikita V. Shirokov Committed by Daniel Borkmann
Browse files

bpf: adding tests for bpf_xdp_adjust_tail 



adding selftests for bpf_xdp_adjust_tail helper. in this synthetic test
we are testing that 1) if data_end < data helper will return EINVAL
2) for normal use case packet's length would be reduced.

Signed-off-by: default avatarNikita V. Shirokov <tehnerd@tehnerd.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent 587b80cc

tools/include/uapi/linux/bpf.h

+9 −1
Original line number Diff line number Diff line
@@ -755,6 +755,13 @@ union bpf_attr { 
 *     @addr: pointer to struct sockaddr to bind socket to

 *     @addr_len: length of sockaddr structure

 *     Return: 0 on success or negative error code

 *

 * int bpf_xdp_adjust_tail(xdp_md, delta)

 *     Adjust the xdp_md.data_end by delta. Only shrinking of packet's

 *     size is supported.

 *     @xdp_md: pointer to xdp_md

 *     @delta: A negative integer to be added to xdp_md.data_end

 *     Return: 0 on success or negative on error

 */

#define __BPF_FUNC_MAPPER(FN)		\

	FN(unspec),			\
@@ -821,7 +828,8 @@ union bpf_attr { 
	FN(msg_apply_bytes),		\

	FN(msg_cork_bytes),		\

	FN(msg_pull_data),		\

	FN(bind),

	FN(bind),			\

	FN(xdp_adjust_tail),



/* integer value in 'imm' field of BPF_CALL instruction selects which helper

 * function eBPF program intends to call

tools/testing/selftests/bpf/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -31,7 +31,7 @@ TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o test_tcp_estats.o test 
	sockmap_verdict_prog.o dev_cgroup.o sample_ret0.o test_tracepoint.o \

	test_l4lb_noinline.o test_xdp_noinline.o test_stacktrace_map.o \

	sample_map_ret0.o test_tcpbpf_kern.o test_stacktrace_build_id.o \

	sockmap_tcp_msg_prog.o connect4_prog.o connect6_prog.o

	sockmap_tcp_msg_prog.o connect4_prog.o connect6_prog.o test_adjust_tail.o



# Order correspond to 'make run_tests' order

TEST_PROGS := test_kmod.sh \

tools/testing/selftests/bpf/bpf_helpers.h

+3 −0
Original line number Diff line number Diff line
@@ -96,6 +96,9 @@ static int (*bpf_msg_pull_data)(void *ctx, int start, int end, int flags) = 
	(void *) BPF_FUNC_msg_pull_data;

static int (*bpf_bind)(void *ctx, void *addr, int addr_len) =

	(void *) BPF_FUNC_bind;

static int (*bpf_xdp_adjust_tail)(void *ctx, int offset) =

	(void *) BPF_FUNC_xdp_adjust_tail;





/* llvm builtin functions that eBPF C program may use to

 * emit BPF_LD_ABS and BPF_LD_IND instructions

tools/testing/selftests/bpf/test_adjust_tail.c

0 → 100644
+30 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0

 * Copyright (c) 2018 Facebook

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of version 2 of the GNU General Public

 * License as published by the Free Software Foundation.

 */

#include <linux/bpf.h>

#include <linux/if_ether.h>

#include "bpf_helpers.h"



int _version SEC("version") = 1;



SEC("xdp_adjust_tail")

int _xdp_adjust_tail(struct xdp_md *xdp)

{

	void *data_end = (void *)(long)xdp->data_end;

	void *data = (void *)(long)xdp->data;

	int offset = 0;



	if (data_end - data == 54)

		offset = 256;

	else

		offset = 20;

	if (bpf_xdp_adjust_tail(xdp, 0 - offset))

		return XDP_DROP;

	return XDP_TX;

}



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

tools/testing/selftests/bpf/test_progs.c

+32 −0
Original line number Diff line number Diff line
@@ -166,6 +166,37 @@ static void test_xdp(void) 
	bpf_object__close(obj);

}



static void test_xdp_adjust_tail(void)

{

	const char *file = "./test_adjust_tail.o";

	struct bpf_object *obj;

	char buf[128];

	__u32 duration, retval, size;

	int err, prog_fd;



	err = bpf_prog_load(file, BPF_PROG_TYPE_XDP, &obj, &prog_fd);

	if (err) {

		error_cnt++;

		return;

	}



	err = bpf_prog_test_run(prog_fd, 1, &pkt_v4, sizeof(pkt_v4),

				buf, &size, &retval, &duration);



	CHECK(err || errno || retval != XDP_DROP,

	      "ipv4", "err %d errno %d retval %d size %d\n",

	      err, errno, retval, size);



	err = bpf_prog_test_run(prog_fd, 1, &pkt_v6, sizeof(pkt_v6),

				buf, &size, &retval, &duration);

	CHECK(err || errno || retval != XDP_TX || size != 54,

	      "ipv6", "err %d errno %d retval %d size %d\n",

	      err, errno, retval, size);

	bpf_object__close(obj);

}







#define MAGIC_VAL 0x1234

#define NUM_ITER 100000

#define VIP_NUM 5
@@ -1177,6 +1208,7 @@ int main(void) 
{

	test_pkt_access();

	test_xdp();

	test_xdp_adjust_tail();

	test_l4lb_all();

	test_xdp_noinline();

	test_tcp_estats();