On 2/6/21 1:36 PM, Arjun Roy wrote:
> From: Arjun Roy <arjun...@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 <arjun...@google.com>
> Signed-off-by: Eric Dumazet <eduma...@google.com>
> Signed-off-by: Soheil Hassas Yeganeh <soh...@google.com>
> Suggested-by: David Ahern <dsah...@gmail.com>
> Suggested-by: Leon Romanovsky <l...@kernel.org>
> Suggested-by: Jakub Kicinski <k...@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..c8469c579ed8 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 -EINVAL;
> lock_sock(sk);
> err = tcp_zerocopy_receive(sk, &zc, &tss);
> release_sock(sk);
>
The 'switch (len)' statement needs to be updated now that 'len' is not
going to end on the 'msg_flags' boundary? But then, how did that work
before if there was 4 byte padding?
Maybe I am missing something here. You currently have:
switch (len) {
case offsetofend(struct tcp_zerocopy_receive, msg_flags):
which should == 60, yet the struct size is 64 with 4-bytes of padding. A
user doing
int optlen = sizeof(struct tcp_zerocopy_receive);
getsockopt(...., &optlen)
would pass in a value of 64, right?
