[net] tcp: Explicitly mark reserved field in tcp_zerocopy_receive args.

[net] tcp: Explicitly mark reserved field in tcp_zerocopy_receive args.

[Arjun Roy]

From: Arjun Roy <arjunroy@google.com>

Explicitly define reserved field and require it to be 0-valued.

Fixes: 7eeba1706eba ("tcp: Add receive timestamp support for receive zerocopy.")
Signed-off-by: Arjun Roy <arjunroy@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Suggested-by: David Ahern <dsahern@gmail.com>
Suggested-by: Leon Romanovsky <leon@kernel.org>
Suggested-by: Jakub Kicinski <kuba@kernel.org>
---
 include/uapi/linux/tcp.h | 2 +-
 net/ipv4/tcp.c           | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
index 42fc5a640df4..8fc09e8638b3 100644
--- a/include/uapi/linux/tcp.h
+++ b/include/uapi/linux/tcp.h
@@ -357,6 +357,6 @@ struct tcp_zerocopy_receive {
 	__u64 msg_control; /* ancillary data */
 	__u64 msg_controllen;
 	__u32 msg_flags;
-	/* __u32 hole;  Next we must add >1 u32 otherwise length checks fail. */
+	__u32 reserved; /* set to 0 for now */
 };
 #endif /* _UAPI_LINUX_TCP_H */
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index e1a17c6b473c..97aee57ab9b4 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -4159,6 +4159,8 @@ static int do_tcp_getsockopt(struct sock *sk, int level,
 		}
 		if (copy_from_user(&zc, optval, len))
 			return -EFAULT;
+		if (zc.reserved)
+			return -EOPNOTSUPP;
 		lock_sock(sk);
 		err = tcp_zerocopy_receive(sk, &zc, &tss);
 		release_sock(sk);
-- 
2.30.0.478.g8a0d178c01-goog

Re: [net] tcp: Explicitly mark reserved field in tcp_zerocopy_receive args.

[David Ahern]

On 2/5/21 4:01 PM, Arjun Roy wrote:
> From: Arjun Roy <arjunroy@google.com>
> 
> Explicitly define reserved field and require it to be 0-valued.
> 
> Fixes: 7eeba1706eba ("tcp: Add receive timestamp support for receive zerocopy.")
> Signed-off-by: Arjun Roy <arjunroy@google.com>
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
> Suggested-by: David Ahern <dsahern@gmail.com>
> Suggested-by: Leon Romanovsky <leon@kernel.org>
> Suggested-by: Jakub Kicinski <kuba@kernel.org>
> ---
>  include/uapi/linux/tcp.h | 2 +-
>  net/ipv4/tcp.c           | 2 ++
>  2 files changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
> index 42fc5a640df4..8fc09e8638b3 100644
> --- a/include/uapi/linux/tcp.h
> +++ b/include/uapi/linux/tcp.h
> @@ -357,6 +357,6 @@ struct tcp_zerocopy_receive {
>  	__u64 msg_control; /* ancillary data */
>  	__u64 msg_controllen;
>  	__u32 msg_flags;
> -	/* __u32 hole;  Next we must add >1 u32 otherwise length checks fail. */
> +	__u32 reserved; /* set to 0 for now */
>  };
>  #endif /* _UAPI_LINUX_TCP_H */
> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
> index e1a17c6b473c..97aee57ab9b4 100644
> --- a/net/ipv4/tcp.c
> +++ b/net/ipv4/tcp.c
> @@ -4159,6 +4159,8 @@ static int do_tcp_getsockopt(struct sock *sk, int level,
>  		}
>  		if (copy_from_user(&zc, optval, len))
>  			return -EFAULT;
> +		if (zc.reserved)
> +			return -EOPNOTSUPP;

usually invalid values for uapi return -EINVAL

Re: [net] tcp: Explicitly mark reserved field in tcp_zerocopy_receive args.

[Arjun Roy]

On Fri, Feb 5, 2021 at 10:57 PM David Ahern <dsahern@gmail.com> wrote:
>
> On 2/5/21 4:01 PM, Arjun Roy wrote:
> > From: Arjun Roy <arjunroy@google.com>
> >
> > Explicitly define reserved field and require it to be 0-valued.
> >
> > Fixes: 7eeba1706eba ("tcp: Add receive timestamp support for receive zerocopy.")
> > Signed-off-by: Arjun Roy <arjunroy@google.com>
> > Signed-off-by: Eric Dumazet <edumazet@google.com>
> > Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
> > Suggested-by: David Ahern <dsahern@gmail.com>
> > Suggested-by: Leon Romanovsky <leon@kernel.org>
> > Suggested-by: Jakub Kicinski <kuba@kernel.org>
> > ---
> >  include/uapi/linux/tcp.h | 2 +-
> >  net/ipv4/tcp.c           | 2 ++
> >  2 files changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
> > index 42fc5a640df4..8fc09e8638b3 100644
> > --- a/include/uapi/linux/tcp.h
> > +++ b/include/uapi/linux/tcp.h
> > @@ -357,6 +357,6 @@ struct tcp_zerocopy_receive {
> >       __u64 msg_control; /* ancillary data */
> >       __u64 msg_controllen;
> >       __u32 msg_flags;
> > -     /* __u32 hole;  Next we must add >1 u32 otherwise length checks fail. */
> > +     __u32 reserved; /* set to 0 for now */
> >  };
> >  #endif /* _UAPI_LINUX_TCP_H */
> > diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
> > index e1a17c6b473c..97aee57ab9b4 100644
> > --- a/net/ipv4/tcp.c
> > +++ b/net/ipv4/tcp.c
> > @@ -4159,6 +4159,8 @@ static int do_tcp_getsockopt(struct sock *sk, int level,
> >               }
> >               if (copy_from_user(&zc, optval, len))
> >                       return -EFAULT;
> > +             if (zc.reserved)
> > +                     return -EOPNOTSUPP;
>
> usually invalid values for uapi return -EINVAL

I'll send out a v2 with that changed then.

-Arjun