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

John Fastabend
2018-06-13T17:50:36Z

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 <edumazet@google.com>
Signed-off-by: John Fastabend <john.fastabend@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);
}