bpf: sockmap only allow ESTABLISHED sock state

After this patch we only allow socks that are in ESTABLISHED state or
are being added via a sock_ops event that is transitioning into an
ESTABLISHED state. By allowing sock_ops events we allow users to
manage sockmaps directly from sock ops programs. The two supported
sock_ops ops are BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB and
BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB.

Similar to TLS ULP this ensures sk_user_data is correct.

Reported-by: Eric Dumazet <edumazet@google.com>
Fixes: 1aa12bdf1bfb ("bpf: sockmap, add sock close() hook to remove socks")
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 30 insertions, 1 deletions

diff --git a/kernel/bpf/sockmap.c b/kernel/bpf/sockmap.c
index 488ef9663c01..1f97b559892a 100644
--- a/kernel/bpf/sockmap.c
+++ b/kernel/bpf/sockmap.c
@@ -2097,8 +2097,12 @@ static int sock_map_update_elem(struct bpf_map *map,
                 return -EINVAL;
         }
 
+        /* ULPs are currently supported only for TCP sockets in ESTABLISHED
+         * state.
+         */
         if (skops.sk->sk_type != SOCK_STREAM ||
-            skops.sk->sk_protocol != IPPROTO_TCP) {
+            skops.sk->sk_protocol != IPPROTO_TCP ||
+            skops.sk->sk_state != TCP_ESTABLISHED) {
                 fput(socket->file);
                 return -EOPNOTSUPP;
         }
@@ -2453,6 +2457,16 @@ static int sock_hash_update_elem(struct bpf_map *map,
                 return -EINVAL;
         }
 
+        /* ULPs are currently supported only for TCP sockets in ESTABLISHED
+         * state.
+         */
+        if (skops.sk->sk_type != SOCK_STREAM ||
+            skops.sk->sk_protocol != IPPROTO_TCP ||
+            skops.sk->sk_state != TCP_ESTABLISHED) {
+                fput(socket->file);
+                return -EOPNOTSUPP;
+        }
+
         lock_sock(skops.sk);
         preempt_disable();
         rcu_read_lock();
@@ -2543,10 +2557,22 @@ const struct bpf_map_ops sock_hash_ops = {
         .map_check_btf = map_check_no_btf,
 };
 
+static bool bpf_is_valid_sock_op(struct bpf_sock_ops_kern *ops)
+{
+        return ops->op == BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB ||
+               ops->op == BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB;
+}
 BPF_CALL_4(bpf_sock_map_update, struct bpf_sock_ops_kern *, bpf_sock,
            struct bpf_map *, map, void *, key, u64, flags)
 {
         WARN_ON_ONCE(!rcu_read_lock_held());
+
+        /* ULPs are currently supported only for TCP sockets in ESTABLISHED
+         * state. This checks that the sock ops triggering the update is
+         * one indicating we are (or will be soon) in an ESTABLISHED state.
+         */
+        if (!bpf_is_valid_sock_op(bpf_sock))
+                return -EOPNOTSUPP;
         return sock_map_ctx_update_elem(bpf_sock, map, key, flags);
 }
 
@@ -2565,6 +2591,9 @@ BPF_CALL_4(bpf_sock_hash_update, struct bpf_sock_ops_kern *, bpf_sock,
            struct bpf_map *, map, void *, key, u64, flags)
 {
         WARN_ON_ONCE(!rcu_read_lock_held());
+
+        if (!bpf_is_valid_sock_op(bpf_sock))
+                return -EOPNOTSUPP;
         return sock_hash_ctx_update_elem(bpf_sock, map, key, flags);
 }