[net PATCH 1/5] bpf: enforce TCP only support for sockmap

[John Fastabend]

From: John Fastabend <john.fastab...@gmail.com>

Only TCP sockets have been tested and at the moment the state change
callback only handles TCP sockets. This adds a check to ensure that
sockets actually being added are TCP sockets.

For net-next we can consider UDP support.

Signed-off-by: John Fastabend <john.fastab...@gmail.com>
Acked-by: Daniel Borkmann <dan...@iogearbox.net>
---
 kernel/bpf/sockmap.c                    |    6 ++++++
 tools/testing/selftests/bpf/test_maps.c |   12 +++++++++++-
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/kernel/bpf/sockmap.c b/kernel/bpf/sockmap.c
index 6424ce0..c68899d 100644
--- a/kernel/bpf/sockmap.c
+++ b/kernel/bpf/sockmap.c
@@ -840,6 +840,12 @@ static int sock_map_update_elem(struct bpf_map *map,
                return -EINVAL;
        }
 
+       if (skops.sk->sk_type != SOCK_STREAM ||
+           skops.sk->sk_protocol != IPPROTO_TCP) {
+               fput(socket->file);
+               return -EOPNOTSUPP;
+       }
+
        err = sock_map_ctx_update_elem(&skops, map, key, flags);
        fput(socket->file);
        return err;
diff --git a/tools/testing/selftests/bpf/test_maps.c 
b/tools/testing/selftests/bpf/test_maps.c
index fe3a443..50ce52d 100644
--- a/tools/testing/selftests/bpf/test_maps.c
+++ b/tools/testing/selftests/bpf/test_maps.c
@@ -466,7 +466,7 @@ static void test_sockmap(int tasks, void *data)
        int one = 1, map_fd_rx, map_fd_tx, map_fd_break, s, sc, rc;
        struct bpf_map *bpf_map_rx, *bpf_map_tx, *bpf_map_break;
        int ports[] = {50200, 50201, 50202, 50204};
-       int err, i, fd, sfd[6] = {0xdeadbeef};
+       int err, i, fd, udp, sfd[6] = {0xdeadbeef};
        u8 buf[20] = {0x0, 0x5, 0x3, 0x2, 0x1, 0x0};
        int parse_prog, verdict_prog;
        struct sockaddr_in addr;
@@ -548,6 +548,16 @@ static void test_sockmap(int tasks, void *data)
                goto out_sockmap;
        }
 
+       /* Test update with unsupported UDP socket */
+       udp = socket(AF_INET, SOCK_DGRAM, 0);
+       i = 0;
+       err = bpf_map_update_elem(fd, &i, &udp, BPF_ANY);
+       if (!err) {
+               printf("Failed socket SOCK_DGRAM allowed '%i:%i'\n",
+                      i, udp);
+               goto out_sockmap;
+       }
+
        /* Test update without programs */
        for (i = 0; i < 6; i++) {
                err = bpf_map_update_elem(fd, &i, &sfd[i], BPF_ANY);