Commit f2a6ee92 authored by Prankur Gupta's avatar Prankur Gupta Committed by Daniel Borkmann
Browse files

selftests/bpf: Add tests for {set|get} socket option from setsockopt BPF 



Adding selftests for the newly added functionality to call bpf_setsockopt()
and bpf_getsockopt() from setsockopt BPF programs.

Test Details:

1. BPF Program

   Checks for changes in IPV6_TCLASS(SOL_IPV6) via setsockopt
   If the cca for the socket is not cubic do nothing
   If the newly set value for IPV6_TCLASS is 45 (0x2d) (as per our use-case)
   then change the cc from cubic to reno

2. User Space Program

   Creates an AF_INET6 socket and set the cca for that to be "cubic"
   Attach the program and set the IPV6_TCLASS to 0x2d using setsockopt
   Verify the cca for the socket changed to reno

Signed-off-by: default avatarPrankur Gupta <prankgup@fb.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarSong Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210817224221.3257826-3-prankgup@fb.com
parent 2c531639

tools/testing/selftests/bpf/bpf_tcp_helpers.h

+18 −0
Original line number Diff line number Diff line
@@ -12,6 +12,10 @@ 
SEC("struct_ops/"#name) \

BPF_PROG(name, args)



#ifndef SOL_TCP

#define SOL_TCP 6

#endif



#define tcp_jiffies32 ((__u32)bpf_jiffies64())



struct sock_common {
@@ -203,6 +207,20 @@ static __always_inline bool tcp_is_cwnd_limited(const struct sock *sk) 
	return !!BPF_CORE_READ_BITFIELD(tp, is_cwnd_limited);

}



static __always_inline bool tcp_cc_eq(const char *a, const char *b)

{

	int i;



	for (i = 0; i < TCP_CA_NAME_MAX; i++) {

		if (a[i] != b[i])

			return false;

		if (!a[i])

			break;

	}



	return true;

}



extern __u32 tcp_slow_start(struct tcp_sock *tp, __u32 acked) __ksym;

extern void tcp_cong_avoid_ai(struct tcp_sock *tp, __u32 w, __u32 acked) __ksym;

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

0 → 100644
+70 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2021 Facebook */

#include <test_progs.h>

#include <netinet/tcp.h>

#include "sockopt_qos_to_cc.skel.h"



static void run_setsockopt_test(int cg_fd, int sock_fd)

{

	socklen_t optlen;

	char cc[16]; /* TCP_CA_NAME_MAX */

	int buf;

	int err = -1;



	buf = 0x2D;

	err = setsockopt(sock_fd, SOL_IPV6, IPV6_TCLASS, &buf, sizeof(buf));

	if (!ASSERT_OK(err, "setsockopt(sock_fd, IPV6_TCLASS)"))

		return;



	/* Verify the setsockopt cc change */

	optlen = sizeof(cc);

	err = getsockopt(sock_fd, SOL_TCP, TCP_CONGESTION, cc, &optlen);

	if (!ASSERT_OK(err, "getsockopt(sock_fd, TCP_CONGESTION)"))

		return;



	if (!ASSERT_STREQ(cc, "reno", "getsockopt(sock_fd, TCP_CONGESTION)"))

		return;

}



void test_sockopt_qos_to_cc(void)

{

	struct sockopt_qos_to_cc *skel;

	char cc_cubic[16] = "cubic"; /* TCP_CA_NAME_MAX */

	int cg_fd = -1;

	int sock_fd = -1;

	int err;



	cg_fd = test__join_cgroup("/sockopt_qos_to_cc");

	if (!ASSERT_GE(cg_fd, 0, "cg-join(sockopt_qos_to_cc)"))

		return;



	skel = sockopt_qos_to_cc__open_and_load();

	if (!ASSERT_OK_PTR(skel, "skel"))

		goto done;



	sock_fd = socket(AF_INET6, SOCK_STREAM, 0);

	if (!ASSERT_GE(sock_fd, 0, "v6 socket open"))

		goto done;



	err = setsockopt(sock_fd, SOL_TCP, TCP_CONGESTION, &cc_cubic,

			 sizeof(cc_cubic));

	if (!ASSERT_OK(err, "setsockopt(sock_fd, TCP_CONGESTION)"))

		goto done;



	skel->links.sockopt_qos_to_cc =

		bpf_program__attach_cgroup(skel->progs.sockopt_qos_to_cc,

					   cg_fd);

	if (!ASSERT_OK_PTR(skel->links.sockopt_qos_to_cc,

			   "prog_attach(sockopt_qos_to_cc)"))

		goto done;



	run_setsockopt_test(cg_fd, sock_fd);



done:

	if (sock_fd != -1)

		close(sock_fd);

	if (cg_fd != -1)

		close(cg_fd);

	/* destroy can take null and error pointer */

	sockopt_qos_to_cc__destroy(skel);

}

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

0 → 100644
+39 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2021 Facebook */

#include <string.h>

#include <linux/tcp.h>

#include <netinet/in.h>

#include <linux/bpf.h>

#include <bpf/bpf_helpers.h>

#include "bpf_tcp_helpers.h"



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



SEC("cgroup/setsockopt")

int sockopt_qos_to_cc(struct bpf_sockopt *ctx)

{

	void *optval_end = ctx->optval_end;

	int *optval = ctx->optval;

	char buf[TCP_CA_NAME_MAX];

	char cc_reno[TCP_CA_NAME_MAX] = "reno";

	char cc_cubic[TCP_CA_NAME_MAX] = "cubic";



	if (ctx->level != SOL_IPV6 || ctx->optname != IPV6_TCLASS)

		return 1;



	if (optval + 1 > optval_end)

		return 0; /* EPERM, bounds check */



	if (bpf_getsockopt(ctx->sk, SOL_TCP, TCP_CONGESTION, &buf, sizeof(buf)))

		return 0;



	if (!tcp_cc_eq(buf, cc_cubic))

		return 0;



	if (*optval == 0x2d) {

		if (bpf_setsockopt(ctx->sk, SOL_TCP, TCP_CONGESTION, &cc_reno,

				sizeof(cc_reno)))

			return 0;

	}

	return 1;

}