[PATCH 4.18 36/53] bpf: sockmap only allow ESTABLISHED sock state

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

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

[ Upstream commit 5607fff303636d48b88414c6be353d9fed700af2 ]

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>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 kernel/bpf/sockmap.c |   31 ++++++++++++++++++++++++++++++-
 1 file changed, 30 insertions(+), 1 deletion(-)

--- a/kernel/bpf/sockmap.c
+++ b/kernel/bpf/sockmap.c
@@ -2100,8 +2100,12 @@ static int sock_map_update_elem(struct b
 		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;
 	}
@@ -2456,6 +2460,16 @@ static int sock_hash_update_elem(struct
 		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();
@@ -2544,10 +2558,22 @@ const struct bpf_map_ops sock_hash_ops =
 	.map_release_uref = sock_map_release,
 };
 
+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);
 }
 
@@ -2566,6 +2592,9 @@ BPF_CALL_4(bpf_sock_hash_update, struct
 	   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);
 }