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

Those hooks run as BPF_CGROUP_RUN_SA_PROG_LOCK and operate on a locked socket.

Note that we could remove the switch for prog->expected_attach_type altogether
since all current sock_addr attach types are covered. However, it makes sense
to keep it as a safe-guard in case new sock_addr attach types are added that
might not operate on a locked socket. Therefore, avoid to let this slip through.
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210127232853.3753823-5-sdf@google.com

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_RECVMSG:
+		case BPF_CGROUP_UDP6_RECVMSG:
 		case BPF_CGROUP_UDP4_SENDMSG:
 		case BPF_CGROUP_UDP6_SENDMSG:
 		case BPF_CGROUP_INET4_GETPEERNAME:
@@ -7039,6 +7041,8 @@ 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_RECVMSG:
+		case BPF_CGROUP_UDP6_RECVMSG:
 		case BPF_CGROUP_UDP4_SENDMSG:
 		case BPF_CGROUP_UDP6_SENDMSG:
 		case BPF_CGROUP_INET4_GETPEERNAME:

tools/testing/selftests/bpf/progs/recvmsg4_prog.c

@@ -8,6 +8,8 @@
 #include <bpf/bpf_helpers.h>
 #include <bpf/bpf_endian.h>
 
+#include <bpf_sockopt_helpers.h>
+
 #define SERV4_IP		0xc0a801feU /* 192.168.1.254 */
 #define SERV4_PORT		4040
 
@@ -28,6 +30,9 @@ int recvmsg4_prog(struct bpf_sock_addr *ctx)
 	if (ctx->type != SOCK_STREAM && ctx->type != SOCK_DGRAM)
 		return 1;
 
+	if (!get_set_sk_priority(ctx))
+		return 1;
+
 	ctx->user_ip4 = bpf_htonl(SERV4_IP);
 	ctx->user_port = bpf_htons(SERV4_PORT);
 

tools/testing/selftests/bpf/progs/recvmsg6_prog.c

@@ -8,6 +8,8 @@
 #include <bpf/bpf_helpers.h>
 #include <bpf/bpf_endian.h>
 
+#include <bpf_sockopt_helpers.h>
+
 #define SERV6_IP_0		0xfaceb00c /* face:b00c:1234:5678::abcd */
 #define SERV6_IP_1		0x12345678
 #define SERV6_IP_2		0x00000000
@@ -31,6 +33,9 @@ int recvmsg6_prog(struct bpf_sock_addr *ctx)
 	if (ctx->type != SOCK_STREAM && ctx->type != SOCK_DGRAM)
 		return 1;
 
+	if (!get_set_sk_priority(ctx))
+		return 1;
+
 	ctx->user_ip6[0] = bpf_htonl(SERV6_IP_0);
 	ctx->user_ip6[1] = bpf_htonl(SERV6_IP_1);
 	ctx->user_ip6[2] = bpf_htonl(SERV6_IP_2);