linux-stable.git/net/compat.c, branch v4.19.78

sock: Make sock->sk_stamp thread-safe

2019-01-09T16:38:33+00:00

[ Upstream commit 3a0ed3e9619738067214871e9cb826fa23b2ddb9 ]

Al Viro mentioned (Message-ID
<20170626041334.GZ10672@ZenIV.linux.org.uk>)
that there is probably a race condition
lurking in accesses of sk_stamp on 32-bit machines.

sock->sk_stamp is of type ktime_t which is always an s64.
On a 32 bit architecture, we might run into situations of
unsafe access as the access to the field becomes non atomic.

Use seqlocks for synchronization.
This allows us to avoid using spinlocks for readers as
readers do not need mutual exclusion.

Another approach to solve this is to require sk_lock for all
modifications of the timestamps. The current approach allows
for timestamps to have their own lock: sk_stamp_lock.
This allows for the patch to not compete with already
existing critical sections, and side effects are limited
to the paths in the patch.

The addition of the new field maintains the data locality
optimizations from
commit 9115e8cd2a0c ("net: reorganize struct sock for better data
locality")

Note that all the instances of the sk_stamp accesses
are either through the ioctl or the syscall recvmsg.

Signed-off-by: Deepa Dinamani 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

net: avoid unnecessary sock_flag() check when enable timestamp

2018-08-06T17:42:48+00:00

The sock_flag() check is alreay inside sock_enable_timestamp(), so it is
unnecessary checking it in the caller.

    void sock_enable_timestamp(struct sock *sk, int flag)
    {
        if (!sock_flag(sk, flag)) {
            ...
        }
    }

Signed-off-by: Yafang Shao 
Signed-off-by: David S. Miller

net: support compat 64-bit time in {s,g}etsockopt

2018-04-27T23:46:06+00:00

For the x32 ABI, struct timeval has two 64-bit fields. However
the kernel currently interprets the user-space values used for
the SO_RCVTIMEO and SO_SNDTIMEO socket options as having a pair
of 32-bit fields.

When the seconds portion of the requested timeout is less than 2**32,
the seconds portion of the effective timeout is correct but the
microseconds portion is zero.  When the seconds portion of the
requested timeout is zero and the microseconds portion is non-zero,
the kernel interprets the timeout as zero (never timeout).

Fix by using 64-bit time for SO_RCVTIMEO/SO_SNDTIMEO as required
for the ABI.

The code included below demonstrates the problem.

Results before patch:
    $ gcc -m64 -Wall -O2 -o socktmo socktmo.c && ./socktmo
    recv time: 2.008181 seconds
    send time: 2.015985 seconds

    $ gcc -m32 -Wall -O2 -o socktmo socktmo.c && ./socktmo
    recv time: 2.016763 seconds
    send time: 2.016062 seconds

    $ gcc -mx32 -Wall -O2 -o socktmo socktmo.c && ./socktmo
    recv time: 1.007239 seconds
    send time: 1.023890 seconds

Results after patch:
    $ gcc -m64 -O2 -Wall -o socktmo socktmo.c && ./socktmo
    recv time: 2.010062 seconds
    send time: 2.015836 seconds

    $ gcc -m32 -O2 -Wall -o socktmo socktmo.c && ./socktmo
    recv time: 2.013974 seconds
    send time: 2.015981 seconds

    $ gcc -mx32 -O2 -Wall -o socktmo socktmo.c && ./socktmo
    recv time: 2.030257 seconds
    send time: 2.013383 seconds

 #include 
 #include 
 #include 
 #include 
 #include 

 void checkrc(char *str, int rc)
 {
         if (rc >= 0)
                 return;

         perror(str);
         exit(1);
 }

 static char buf[1024];
 int main(int argc, char **argv)
 {
         int rc;
         int socks[2];
         struct timeval tv;
         struct timeval start, end, delta;

         rc = socketpair(AF_UNIX, SOCK_STREAM, 0, socks);
         checkrc("socketpair", rc);

         /* set timeout to 1.999999 seconds */
         tv.tv_sec = 1;
         tv.tv_usec = 999999;
         rc = setsockopt(socks[0], SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof tv);
         rc = setsockopt(socks[0], SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof tv);
         checkrc("setsockopt", rc);

         /* measure actual receive timeout */
         gettimeofday(&start, NULL);
         rc = recv(socks[0], buf, sizeof buf, 0);
         gettimeofday(&end, NULL);
         timersub(&end, &start, &delta);

         printf("recv time: %ld.%06ld seconds\n",
                (long)delta.tv_sec, (long)delta.tv_usec);

         /* fill send buffer */
         do {
                 rc = send(socks[0], buf, sizeof buf, 0);
         } while (rc > 0);

         /* measure actual send timeout */
         gettimeofday(&start, NULL);
         rc = send(socks[0], buf, sizeof buf, 0);
         gettimeofday(&end, NULL);
         timersub(&end, &start, &delta);

         printf("send time: %ld.%06ld seconds\n",
                (long)delta.tv_sec, (long)delta.tv_usec);
         exit(0);
 }

Fixes: 515c7af85ed9 ("x32: Use compat shims for {g,s}etsockopt")
Reported-by: Gopal RajagopalSai 
Signed-off-by: Lance Richardson 
Signed-off-by: David S. Miller

net: socket: add __compat_sys_...msg() helpers; remove in-kernel calls to compat syscalls

2018-04-02T18:15:20+00:00

Using the net-internal helpers __compat_sys_...msg() allows us to avoid
the internal calls to the compat_sys_...msg() syscalls.
compat_sys_recvmmsg() is handled in a different patch.

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net

Cc: David S. Miller 
Cc: netdev@vger.kernel.org
Signed-off-by: Dominik Brodowski

net: socket: add __compat_sys_recvmmsg() helper; remove in-kernel call to compat syscall

2018-04-02T18:15:19+00:00

Using the net-internal helper __compat_sys_recvmmsg() allows us to avoid
the internal calls to the compat_sys_recvmmsg() syscall.

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net

Cc: David S. Miller 
Cc: netdev@vger.kernel.org
Signed-off-by: Dominik Brodowski

net: socket: add __compat_sys_getsockopt() helper; remove in-kernel call to compat syscall

2018-04-02T18:15:19+00:00

Using the net-internal helper __compat_sys_getsockopt() allows us to avoid
the internal calls to the compat_sys_getsockopt() syscall.

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net

Cc: David S. Miller 
Cc: netdev@vger.kernel.org
Signed-off-by: Dominik Brodowski

net: socket: add __compat_sys_setsockopt() helper; remove in-kernel call to compat syscall

2018-04-02T18:15:18+00:00

Using the net-internal helper __compat_sys_setsockopt() allows us to avoid
the internal calls to the compat_sys_setsockopt() syscall.

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net

Cc: David S. Miller 
Cc: netdev@vger.kernel.org
Signed-off-by: Dominik Brodowski

net: socket: add __compat_sys_recvfrom() helper; remove in-kernel call to compat syscall

2018-04-02T18:15:17+00:00

Using the net-internal helper __compat_sys_recvfrom() allows us to avoid
the internal calls to the compat_sys_recvfrom() syscall.

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net

Cc: David S. Miller 
Cc: netdev@vger.kernel.org
Signed-off-by: Dominik Brodowski

net: socket: replace call to sys_recv() with __sys_recvfrom()

2018-04-02T18:15:16+00:00

sys_recv() merely expands the parameters to __sys_recvfrom() by NULL and
NULL. Open-code this in the two places which used sys_recv() as a wrapper
to __sys_recvfrom().

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net

Cc: David S. Miller 
Cc: netdev@vger.kernel.org
Signed-off-by: Dominik Brodowski

net: socket: replace calls to sys_send() with __sys_sendto()

2018-04-02T18:15:16+00:00

sys_send() merely expands the parameters to __sys_sendto() by NULL and 0.
Open-code this in the two places which used sys_send() as a wrapper to
__sys_sendto().

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net

Cc: David S. Miller 
Cc: netdev@vger.kernel.org
Signed-off-by: Dominik Brodowski