Commit 62476cc1 authored by Stanislav Fomichev's avatar Stanislav Fomichev Committed by Daniel Borkmann
Browse files

bpf: Enable bpf_{g,s}etsockopt in BPF_CGROUP_UDP{4,6}_SENDMSG 



Can be used to query/modify socket state for unconnected UDP sendmsg.
Those hooks run as BPF_CGROUP_RUN_SA_PROG_LOCK and operate on
a locked socket.

Signed-off-by: default avatarStanislav Fomichev <sdf@google.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210127232853.3753823-2-sdf@google.com
parent 211a741c

net/core/filter.c

+4 −0
Original line number Diff line number Diff line
@@ -7023,6 +7023,8 @@ sock_addr_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) 
		case BPF_CGROUP_INET6_BIND:

		case BPF_CGROUP_INET4_CONNECT:

		case BPF_CGROUP_INET6_CONNECT:

		case BPF_CGROUP_UDP4_SENDMSG:

		case BPF_CGROUP_UDP6_SENDMSG:

			return &bpf_sock_addr_setsockopt_proto;

		default:

			return NULL;
@@ -7033,6 +7035,8 @@ sock_addr_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) 
		case BPF_CGROUP_INET6_BIND:

		case BPF_CGROUP_INET4_CONNECT:

		case BPF_CGROUP_INET6_CONNECT:

		case BPF_CGROUP_UDP4_SENDMSG:

		case BPF_CGROUP_UDP6_SENDMSG:

			return &bpf_sock_addr_getsockopt_proto;

		default:

			return NULL;

tools/testing/selftests/bpf/bpf_sockopt_helpers.h

0 → 100644
+21 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */



#include <sys/socket.h>

#include <bpf/bpf_helpers.h>



int get_set_sk_priority(void *ctx)

{

	int prio;



	/* Verify that context allows calling bpf_getsockopt and

	 * bpf_setsockopt by reading and writing back socket

	 * priority.

	 */



	if (bpf_getsockopt(ctx, SOL_SOCKET, SO_PRIORITY, &prio, sizeof(prio)))

		return 0;

	if (bpf_setsockopt(ctx, SOL_SOCKET, SO_PRIORITY, &prio, sizeof(prio)))

		return 0;



	return 1;

}

tools/testing/selftests/bpf/progs/sendmsg4_prog.c

+7 −0
Original line number Diff line number Diff line
@@ -8,6 +8,8 @@ 
#include <bpf/bpf_helpers.h>

#include <bpf/bpf_endian.h>



#include <bpf_sockopt_helpers.h>



#define SRC1_IP4		0xAC100001U /* 172.16.0.1 */

#define SRC2_IP4		0x00000000U

#define SRC_REWRITE_IP4		0x7f000004U
@@ -21,9 +23,14 @@ int _version SEC("version") = 1; 
SEC("cgroup/sendmsg4")

int sendmsg_v4_prog(struct bpf_sock_addr *ctx)

{

	int prio;



	if (ctx->type != SOCK_DGRAM)

		return 0;



	if (!get_set_sk_priority(ctx))

		return 0;



	/* Rewrite source. */

	if (ctx->msg_src_ip4 == bpf_htonl(SRC1_IP4) ||

	    ctx->msg_src_ip4 == bpf_htonl(SRC2_IP4)) {

tools/testing/selftests/bpf/progs/sendmsg6_prog.c

+5 −0
Original line number Diff line number Diff line
@@ -8,6 +8,8 @@ 
#include <bpf/bpf_helpers.h>

#include <bpf/bpf_endian.h>



#include <bpf_sockopt_helpers.h>



#define SRC_REWRITE_IP6_0	0

#define SRC_REWRITE_IP6_1	0

#define SRC_REWRITE_IP6_2	0
@@ -28,6 +30,9 @@ int sendmsg_v6_prog(struct bpf_sock_addr *ctx) 
	if (ctx->type != SOCK_DGRAM)

		return 0;



	if (!get_set_sk_priority(ctx))

		return 0;



	/* Rewrite source. */

	if (ctx->msg_src_ip6[3] == bpf_htonl(1) ||

	    ctx->msg_src_ip6[3] == bpf_htonl(0)) {