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Linux: Only generate 64 bit timestamps for 64 bit time_t recvmsg/recvmmsg

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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>
This commit is contained in:
Adhemerval Zanella
2022-01-27 16:45:18 -03:00
parent 8fba672472
commit 948ce73b31
6 changed files with 330 additions and 26 deletions
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34
sysdeps/unix/sysv/linux/recvmsg.c
View File

@@ -20,29 +20,41 @@
#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_recvmsg (int fd, struct msghdr *msg, int flags)
__libc_recvmsg64 (int fd, struct msghdr *msg, int flags)
{
ssize_t r;
#ifndef __ASSUME_TIME64_SYSCALLS
#if __TIMESIZE != 64
socklen_t orig_controllen = msg != NULL ? msg->msg_controllen : 0;
#endif
#ifdef __ASSUME_RECVMSG_SYSCALL
r = SYSCALL_CANCEL (recvmsg, fd, msg, flags);
#else
r = SOCKETCALL_CANCEL (recvmsg, fd, msg, flags);
#endif
r = __recvmsg_syscall (fd, msg, flags);
#ifndef __ASSUME_TIME64_SYSCALLS
#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)
#if __TIMESIZE != 64
weak_alias (__recvmsg, __recvmsg64)
#endif