[bpf PATCH 2/6] bpf: sockmap only allow ESTABLISHED sock state

[John Fastabend]

Per the note in the TLS ULP (which is actually a generic statement
regarding ULPs)

 /* The TLS ulp is currently supported only for TCP sockets
  * in ESTABLISHED state.
  * Supporting sockets in LISTEN state will require us
  * to modify the accept implementation to clone rather then
  * share the ulp context.
  */

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.

Also tested with 'netserver -6' and 'netperf -H [IPv6]' as well as
'netperf -H [IPv4]'.

Reported-by: Eric Dumazet <eduma...@google.com>
Signed-off-by: John Fastabend <john.fastab...@gmail.com>
---
 kernel/bpf/sockmap.c |   28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/kernel/bpf/sockmap.c b/kernel/bpf/sockmap.c
index f6dd4cd..e5bab52 100644
--- a/kernel/bpf/sockmap.c
+++ b/kernel/bpf/sockmap.c
@@ -1976,8 +1976,12 @@ 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;
        }
@@ -2338,6 +2342,16 @@ 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;
+       }
+
        err = sock_hash_ctx_update_elem(&skops, map, key, flags);
        fput(socket->file);
        return err;
@@ -2423,10 +2437,19 @@ struct sock  *__sock_hash_lookup_elem(struct bpf_map 
*map, void *key)
        .map_delete_elem = sock_hash_delete_elem,
 };
 
+static bool bpf_is_valid_sock(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());
+
+       if (!bpf_is_valid_sock(bpf_sock))
+               return -EOPNOTSUPP;
        return sock_map_ctx_update_elem(bpf_sock, map, key, flags);
 }
 
@@ -2445,6 +2468,9 @@ struct sock  *__sock_hash_lookup_elem(struct bpf_map 
*map, void *key)
           struct bpf_map *, map, void *, key, u64, flags)
 {
        WARN_ON_ONCE(!rcu_read_lock_held());
+
+       if (!bpf_is_valid_sock(bpf_sock))
+               return -EOPNOTSUPP;
        return sock_hash_ctx_update_elem(bpf_sock, map, key, flags);
 }