glibc/sysdeps/unix/sysv/linux/recvmsg.c
Adhemerval Zanella 948ce73b31 Linux: Only generate 64 bit timestamps for 64 bit time_t recvmsg/recvmmsg
The timestamps created by __convert_scm_timestamps only make sense for
64 bit time_t programs, 32 bit time_t programs will ignore 64 bit time_t
timestamps since SO_TIMESTAMP will be defined to old values (either by
glibc or kernel headers).

Worse, if the buffer is not suffice MSG_CTRUNC is set to indicate it
(which breaks some programs [1]).

This patch makes only 64 bit time_t recvmsg and recvmmsg to call
__convert_scm_timestamps.  Also, the assumption to called it is changed
from __ASSUME_TIME64_SYSCALLS to __TIMESIZE != 64 since the setsockopt
might be called by libraries built without __TIME_BITS=64.  The
MSG_CTRUNC is only set for the 64 bit symbols, it should happen only
if 64 bit time_t programs run older kernels.

Checked on x86_64-linux-gnu and i686-linux-gnu.

[1] https://github.com/systemd/systemd/pull/20567

Reviewed-by: Florian Weimer <fweimer@redhat.com>
2022-01-28 18:18:27 -03:00

61 lines
1.7 KiB
C

/* Linux recvmsg syscall wrapper.
Copyright (C) 2016-2022 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <sys/socket.h>
#include <sysdep-cancel.h>
#include <socketcall.h>
static int
__recvmsg_syscall (int fd, struct msghdr *msg, int flags)
{
#ifdef __ASSUME_RECVMSG_SYSCALL
return SYSCALL_CANCEL (recvmsg, fd, msg, flags);
#else
return SOCKETCALL_CANCEL (recvmsg, fd, msg, flags);
#endif
}
ssize_t
__libc_recvmsg64 (int fd, struct msghdr *msg, int flags)
{
ssize_t r;
#if __TIMESIZE != 64
socklen_t orig_controllen = msg != NULL ? msg->msg_controllen : 0;
#endif
r = __recvmsg_syscall (fd, msg, flags);
#if __TIMESIZE != 64
if (r >= 0 && orig_controllen != 0)
__convert_scm_timestamps (msg, orig_controllen);
#endif
return r;
}
#if __TIMESIZE != 64
weak_alias (__libc_recvmsg64, __recvmsg64)
ssize_t
__libc_recvmsg (int fd, struct msghdr *msg, int flags)
{
return __recvmsg_syscall (fd, msg, flags);
}
#endif
weak_alias (__libc_recvmsg, recvmsg)
weak_alias (__libc_recvmsg, __recvmsg)