Re: [net-next v2] tcp: Explicitly mark reserved field in tcp_zerocopy_receive args.
From: David Ahern <hidden>
Date: 2021-02-07 17:50:48
On 2/6/21 1:36 PM, Arjun Roy wrote:
quoted hunk ↗ jump to hunk
From: Arjun Roy <redacted> 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 <redacted> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Soheil Hassas Yeganeh <redacted> Suggested-by: David Ahern <redacted> 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..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?