On Tue, Jan 8, 2019 at 6:24 AM Deepa Dinamani <deepa.kernel@xxxxxxxxx> wrote:
>
> SO_RCVTIMEO and SO_SNDTIMEO socket options use struct timeval
> as the time format. struct timeval is not y2038 safe.
> The subsequent patches in the series add support for new socket
> timeout options with _NEW suffix that are y2038 safe.
> Rename the existing options with _OLD suffix forms so that the
> right option is enabled for userspace applications according
> to the architecture and time_t definition of libc.
>
> Signed-off-by: Deepa Dinamani <deepa.kernel@xxxxxxxxx>
Looks good overall. A few minor concerns:
The description above makes it sound like there is a bug with y2038-safety
in this particular interface, which I think is just not what you meant,
as the change is only needed for compatiblity with new C libraries
that work around the y2038 problem in general by changing their
timeval definition.
> diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
> index 76976d6e50f9..c98ad9777ad9 100644
> --- a/fs/dlm/lowcomms.c
> +++ b/fs/dlm/lowcomms.c
> @@ -1089,12 +1089,12 @@ static void sctp_connect_to_sock(struct connection *con)
> * since O_NONBLOCK argument in connect() function does not work here,
> * then, we should restore the default value of this attribute.
> */
> - kernel_setsockopt(sock, SOL_SOCKET, SO_SNDTIMEO, (char *)&tv,
> + kernel_setsockopt(sock, SOL_SOCKET, SO_SNDTIMEO_OLD, (char *)&tv,
> sizeof(tv));
> result = sock->ops->connect(sock, (struct sockaddr *)&daddr, addr_len,
> 0);
> memset(&tv, 0, sizeof(tv));
> - kernel_setsockopt(sock, SOL_SOCKET, SO_SNDTIMEO, (char *)&tv,
> + kernel_setsockopt(sock, SOL_SOCKET, SO_SNDTIMEO_OLD, (char *)&tv,
> sizeof(tv));
>
> if (result == -EINPROGRESS)
It took me a bit to realize there that this is safe as well even if
we don't use SO_SNDTIMEO_NEW, for the same reason.
> --- a/net/compat.c
> +++ b/net/compat.c
> @@ -378,7 +378,7 @@ static int compat_sock_setsockopt(struct socket *sock, int level, int optname,
> return do_set_attach_filter(sock, level, optname,
> optval, optlen);
> if (!COMPAT_USE_64BIT_TIME &&
> - (optname == SO_RCVTIMEO || optname == SO_SNDTIMEO))
> + (optname == SO_RCVTIMEO_OLD || optname == SO_SNDTIMEO_OLD))
> return do_set_sock_timeout(sock, level, optname, optval, optlen);
>
> return sock_setsockopt(sock, level, optname, optval, optlen);
> @@ -450,7 +450,7 @@ static int compat_sock_getsockopt(struct socket *sock, int level, int optname,
> char __user *optval, int __user *optlen)
> {
> if (!COMPAT_USE_64BIT_TIME &&
> - (optname == SO_RCVTIMEO || optname == SO_SNDTIMEO))
> + (optname == SO_RCVTIMEO_OLD || optname == SO_SNDTIMEO_OLD))
> return do_get_sock_timeout(sock, level, optname, optval, optlen);
> return sock_getsockopt(sock, level, optname, optval, optlen);
> }
I looked at the original code and noticed that it's horrible, which of course
is not your fault, but I wonder if we should just fix it now to avoid that
get_fs()/set_fs() hack, since that code mostly implements what you
also have in your patch 3 (which is done more nicely).
I'll follow up with a patch to demonstrate what I mean here. Your third
patch will then just have to add another code path so we can handle
all of old_timespec32 (for existing 32-bit user space), __kernel_old_timespec
(for sparc64) and __kernel_sock_timeval (for everything else).
Arnd
