Commit 7805fe84 authored by Alexei Starovoitov's avatar Alexei Starovoitov Committed by Daniel Borkmann
Browse files

selftests/bpf: Add tests for program extensions 



Add program extension tests that build on top of fexit_bpf2bpf tests.
Replace three global functions in previously loaded test_pkt_access.c program
with three new implementations:
int get_skb_len(struct __sk_buff *skb);
int get_constant(long val);
int get_skb_ifindex(int val, struct __sk_buff *skb, int var);
New function return the same results as original only if arguments match.

new_get_skb_ifindex() demonstrates that 'skb' argument doesn't have to be first
and only argument of BPF program. All normal skb based accesses are available.

Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarJohn Fastabend <john.fastabend@gmail.com>
Acked-by: default avatarAndrii Nakryiko <andriin@fb.com>
Acked-by: default avatarToke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20200121005348.2769920-4-ast@kernel.org
parent 2db6eab1

tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c

+19 −1
Original line number Diff line number Diff line
@@ -26,7 +26,7 @@ static void test_fexit_bpf2bpf_common(const char *obj_file, 


	link = calloc(sizeof(struct bpf_link *), prog_cnt);

	prog = calloc(sizeof(struct bpf_program *), prog_cnt);

	result = malloc(prog_cnt * sizeof(u64));

	result = malloc((prog_cnt + 32 /* spare */) * sizeof(u64));

	if (CHECK(!link || !prog || !result, "alloc_memory",

		  "failed to alloc memory"))

		goto close_prog;
@@ -106,8 +106,26 @@ static void test_target_yes_callees(void) 
				  prog_name);

}



static void test_func_replace(void)

{

	const char *prog_name[] = {

		"fexit/test_pkt_access",

		"fexit/test_pkt_access_subprog1",

		"fexit/test_pkt_access_subprog2",

		"fexit/test_pkt_access_subprog3",

		"freplace/get_skb_len",

		"freplace/get_skb_ifindex",

		"freplace/get_constant",

	};

	test_fexit_bpf2bpf_common("./fexit_bpf2bpf.o",

				  "./test_pkt_access.o",

				  ARRAY_SIZE(prog_name),

				  prog_name);

}



void test_fexit_bpf2bpf(void)

{

	test_target_no_callees();

	test_target_yes_callees();

	test_func_replace();

}

tools/testing/selftests/bpf/progs/fexit_bpf2bpf.c

+57 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2019 Facebook */

#include <linux/stddef.h>

#include <linux/ipv6.h>

#include <linux/bpf.h>

#include <bpf/bpf_helpers.h>

#include <bpf/bpf_endian.h>

#include "bpf_trace_helpers.h"



struct sk_buff {
@@ -94,4 +97,58 @@ int BPF_PROG(test_subprog3, int val, struct sk_buff *skb, int ret) 
	test_result_subprog3 = 1;

	return 0;

}



__u64 test_get_skb_len = 0;

SEC("freplace/get_skb_len")

int new_get_skb_len(struct __sk_buff *skb)

{

	int len = skb->len;



	if (len != 74)

		return 0;

	test_get_skb_len = 1;

	return 74; /* original get_skb_len() returns skb->len */

}



__u64 test_get_skb_ifindex = 0;

SEC("freplace/get_skb_ifindex")

int new_get_skb_ifindex(int val, struct __sk_buff *skb, int var)

{

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

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

	struct ipv6hdr ip6, *ip6p;

	int ifindex = skb->ifindex;

	__u32 eth_proto;

	__u32 nh_off;



	/* check that BPF extension can read packet via direct packet access */

	if (data + 14 + sizeof(ip6) > data_end)

		return 0;

	ip6p = data + 14;



	if (ip6p->nexthdr != 6 || ip6p->payload_len != __bpf_constant_htons(123))

		return 0;



	/* check that legacy packet access helper works too */

	if (bpf_skb_load_bytes(skb, 14, &ip6, sizeof(ip6)) < 0)

		return 0;

	ip6p = &ip6;

	if (ip6p->nexthdr != 6 || ip6p->payload_len != __bpf_constant_htons(123))

		return 0;



	if (ifindex != 1 || val != 3 || var != 1)

		return 0;

	test_get_skb_ifindex = 1;

	return 3; /* original get_skb_ifindex() returns val * ifindex * var */

}



volatile __u64 test_get_constant = 0;

SEC("freplace/get_constant")

int new_get_constant(long val)

{

	if (val != 123)

		return 0;

	test_get_constant = 1;

	return test_get_constant; /* original get_constant() returns val - 122 */

}

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

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

+7 −1
Original line number Diff line number Diff line
@@ -57,12 +57,18 @@ int get_skb_len(struct __sk_buff *skb) 
	return skb->len;

}



__attribute__ ((noinline))

int get_constant(long val)

{

	return val - 122;

}



int get_skb_ifindex(int, struct __sk_buff *skb, int);



__attribute__ ((noinline))

int test_pkt_access_subprog3(int val, struct __sk_buff *skb)

{

	return get_skb_len(skb) * get_skb_ifindex(val, skb, 1);

	return get_skb_len(skb) * get_skb_ifindex(val, skb, get_constant(123));

}



__attribute__ ((noinline))

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