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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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36
sysdeps/unix/sysv/linux/recvmmsg.c
View File

@@ -19,9 +19,9 @@
#include <sysdep.h>
#include <socketcall.h>
int
__recvmmsg64 (int fd, struct mmsghdr *vmessages, unsigned int vlen, int flags,
struct __timespec64 *timeout)
static int
recvmmsg_syscall (int fd, struct mmsghdr *vmessages, unsigned int vlen,
int flags, struct __timespec64 *timeout)
{
#ifndef __NR_recvmmsg_time64
# define __NR_recvmmsg_time64 __NR_recvmmsg
@@ -44,12 +44,6 @@ __recvmmsg64 (int fd, struct mmsghdr *vmessages, unsigned int vlen, int flags,
pts32 = &ts32;
}
socklen_t csize[IOV_MAX];
if (vlen > IOV_MAX)
vlen = IOV_MAX;
for (int i = 0; i < vlen; i++)
csize[i] = vmessages[i].msg_hdr.msg_controllen;
# ifdef __ASSUME_RECVMMSG_SYSCALL
r = SYSCALL_CANCEL (recvmmsg, fd, vmessages, vlen, flags, pts32);
# else
@@ -59,11 +53,31 @@ __recvmmsg64 (int fd, struct mmsghdr *vmessages, unsigned int vlen, int flags,
{
if (timeout != NULL)
*timeout = valid_timespec_to_timespec64 (ts32);
}
#endif
return r;
}
int
__recvmmsg64 (int fd, struct mmsghdr *vmessages, unsigned int vlen, int flags,
struct __timespec64 *timeout)
{
#if __TIMESIZE != 64
socklen_t csize[IOV_MAX];
if (vlen > IOV_MAX)
vlen = IOV_MAX;
for (int i = 0; i < vlen; i++)
csize[i] = vmessages[i].msg_hdr.msg_controllen;
#endif
int r = recvmmsg_syscall (fd, vmessages, vlen, flags, timeout);
#if __TIMESIZE != 64
if (r > 0)
{
for (int i=0; i < r; i++)
__convert_scm_timestamps (&vmessages[i].msg_hdr, csize[i]);
}
#endif /* __ASSUME_TIME64_SYSCALLS */
#endif
return r;
}
#if __TIMESIZE != 64
@@ -79,7 +93,7 @@ __recvmmsg (int fd, struct mmsghdr *vmessages, unsigned int vlen, int flags,
ts64 = valid_timespec_to_timespec64 (*timeout);
pts64 = &ts64;
}
int r = __recvmmsg64 (fd, vmessages, vlen, flags, pts64);
int r = recvmmsg_syscall (fd, vmessages, vlen, flags, pts64);
if (r >= 0 && timeout != NULL)
/* The remanining timeout will be always less the input TIMEOUT. */
*timeout = valid_timespec64_to_timespec (ts64);