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

diff --git a/net/core/filter.c b/net/core/filter.c
index 9ab94e9..3d7f78a 100644 (file)
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -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;

diff --git a/tools/testing/selftests/bpf/bpf_sockopt_helpers.h b/tools/testing/selftests/bpf/bpf_sockopt_helpers.h
new file mode 100644 (file)
index 0000000..11f3a09
--- /dev/null
+++ b/tools/testing/selftests/bpf/bpf_sockopt_helpers.h
@@ -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;
+}

diff --git a/tools/testing/selftests/bpf/progs/sendmsg4_prog.c b/tools/testing/selftests/bpf/progs/sendmsg4_prog.c
index 092d9da..ac5abc3 100644 (file)
--- a/tools/testing/selftests/bpf/progs/sendmsg4_prog.c
+++ b/tools/testing/selftests/bpf/progs/sendmsg4_prog.c
@@ -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)) {

diff --git a/tools/testing/selftests/bpf/progs/sendmsg6_prog.c b/tools/testing/selftests/bpf/progs/sendmsg6_prog.c
index 255a432..24694b1 100644 (file)
--- a/tools/testing/selftests/bpf/progs/sendmsg6_prog.c
+++ b/tools/testing/selftests/bpf/progs/sendmsg6_prog.c
@@ -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)) {