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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: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210127232853.3753823-2-sdf@google.com
This commit is contained in:
Stanislav Fomichev 2021-01-27 15:28:50 -08:00 committed by Daniel Borkmann
parent 211a741cd3
commit 62476cc1bf
4 changed files with 37 additions and 0 deletions
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4
net/core/filter.c
View File

@ -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;

21
tools/testing/selftests/bpf/bpf_sockopt_helpers.h Normal file
View File

@ -0,0 +1,21 @@
/* 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;
}

7
tools/testing/selftests/bpf/progs/sendmsg4_prog.c
View File

@ -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)) {

5
tools/testing/selftests/bpf/progs/sendmsg6_prog.c
View File

@ -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)) {