Re: [PATCH bpf] bpf: Add sk_is_inet check in tls_sw_has_ctx_tx/rx

[Stanislav Fomichev <stfomichev@gmail.com>]

On 10/30, Zijian Zhang wrote:
> On 10/30/24 8:38 AM, Stanislav Fomichev wrote:
> > On 10/29, Zijian Zhang wrote:
> > > 
> > > On 10/29/24 5:22 PM, Stanislav Fomichev wrote:
> > > > On 10/29, Zijian Zhang wrote:
> > > > > 
> > > > > 
> > > > > On 10/29/24 4:07 PM, Stanislav Fomichev wrote:
> > > > > > On 10/29, zijianzhang@bytedance.com wrote:
> > > ...
> > > > > > > diff --git a/include/net/tls.h b/include/net/tls.h
> > > > > > > index 3a33924db2bc..a65939c7ad61 100644
> > > > > > > --- a/include/net/tls.h
> > > > > > > +++ b/include/net/tls.h
> > > > > > > @@ -390,8 +390,12 @@ tls_offload_ctx_tx(const struct tls_context *tls_ctx)
> > > > > > >     static inline bool tls_sw_has_ctx_tx(const struct sock *sk)
> > > > > > >     {
> > > > > > > -	struct tls_context *ctx = tls_get_ctx(sk);
> > > > > > > +	struct tls_context *ctx;
> > > > > > > +
> > > > > > > +	if (!sk_is_inet(sk))
> > > > > > > +		return false;
> > > > > > > +	ctx = tls_get_ctx(sk);
> > > > > > >     	if (!ctx)
> > > > > > >     		return false;
> > > > > > >     	return !!tls_sw_ctx_tx(ctx);
> > > > > > > @@ -399,8 +403,12 @@ static inline bool tls_sw_has_ctx_tx(const struct sock *sk)
> > > > > > >     static inline bool tls_sw_has_ctx_rx(const struct sock *sk)
> > > > > > >     {
> > > > > > > -	struct tls_context *ctx = tls_get_ctx(sk);
> > > > > > > +	struct tls_context *ctx;
> > > > > > > +
> > > > > > > +	if (!sk_is_inet(sk))
> > > > > > > +		return false;
> > > > > > > +	ctx = tls_get_ctx(sk);
> > > > > > >     	if (!ctx)
> > > > > > >     		return false;
> > > > > > >     	return !!tls_sw_ctx_rx(ctx);
> > > > > > 
> > > > > > This seems like a strange place to fix it. Why does tls_get_ctx return
> > > > > > invalid pointer for non-tls/ulp sockets? Shouldn't it be NULL?
> > > > > > Is sockmap even supposed to work with vsock?
> > > > > 
> > > > > Here is my understanding, please correct me if I am wrong :)
> > > > > ```
> > > > > static inline struct tls_context *tls_get_ctx(const struct sock *sk)
> > > > > {
> > > > > 	const struct inet_connection_sock *icsk = inet_csk(sk);
> > > > > 	return (__force void *)icsk->icsk_ulp_data;
> > > > > }
> > > > > ```
> > > > > tls_get_ctx assumes the socket passed is icsk_socket. However, unix
> > > > > and vsock do not have inet_connection_sock, they have unix_sock and
> > > > > vsock_sock. The offset of icsk_ulp_data are meaningless for them, and
> > > > > they might point to some other values which might not be NULL.
> > > > > 
> > > > > Afaik, sockmap started to support vsock in 634f1a7110b4 ("vsock: support
> > > > > sockmap"), and support unix in 94531cfcbe79 ("af_unix: Add
> > > > > unix_stream_proto for sockmap").
> > > > > 
> > > > > If the above is correct, I find that using inet_test_bit(IS_ICSK, sk)
> > > > > instead of sk_is_inet will be more accurate.
> > > > 
> > > > Thanks for the context, makes sense. And consolidating this sk_is_inet
> > > > check inside tls_get_ctx is worse because it gets called outside of
> > > > sockmap?
> > > 
> > > Yes, tls_get_ctx is invoked in multiple locations, and I want to only
> > > fix sockmap related calls.
> > 
> > Sounds convincing. Unless John/Jakub have better suggestions:
> > 
> > Acked-by: Stanislav Fomichev <sdf@fomichev.me>
> 
> Thanks for the Ack and reviewing!
> 
> In order to make it more accurate, I added inet_test_bit(IS_ICSK, sk)
> check in version2. I just found that sk_is_inet only cannot assure
> inet_csk is valid. For example, udp_sock does not have inet_connection_sock.

Instead of testing IS_ICSK bit, will inet_csk_has_ulp helper work?