[v6,3/3] 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
---
 include/sys/socket.h                          |  10 +-
 sysdeps/unix/sysv/linux/Makefile              |  10 +-
 sysdeps/unix/sysv/linux/recvmmsg.c            |  45 ++-
 sysdeps/unix/sysv/linux/recvmsg.c             |  34 ++-
 .../tst-socket-timestamp-compat-time64.c      |   1 +
 .../sysv/linux/tst-socket-timestamp-compat.c  | 265 ++++++++++++++++++
 6 files changed, 336 insertions(+), 29 deletions(-)
 create mode 100644 sysdeps/unix/sysv/linux/tst-socket-timestamp-compat-time64.c
 create mode 100644 sysdeps/unix/sysv/linux/tst-socket-timestamp-compat.c
  

* Adhemerval Zanella:

> 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
> ---
>  include/sys/socket.h                          |  10 +-
>  sysdeps/unix/sysv/linux/Makefile              |  10 +-
>  sysdeps/unix/sysv/linux/recvmmsg.c            |  45 ++-
>  sysdeps/unix/sysv/linux/recvmsg.c             |  34 ++-
>  .../tst-socket-timestamp-compat-time64.c      |   1 +
>  .../sysv/linux/tst-socket-timestamp-compat.c  | 265 ++++++++++++++++++
>  6 files changed, 336 insertions(+), 29 deletions(-)
>  create mode 100644 sysdeps/unix/sysv/linux/tst-socket-timestamp-compat-time64.c
>  create mode 100644 sysdeps/unix/sysv/linux/tst-socket-timestamp-compat.c

Looks okay.

Reviewed-by: Florian Weimer <fweimer@redhat.com>

Thanks,
Florian
  

On 1/28/22 13:19, Florian Weimer via Libc-alpha wrote:
> * Adhemerval Zanella:
> 
>> 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
>> ---
>>  include/sys/socket.h                          |  10 +-
>>  sysdeps/unix/sysv/linux/Makefile              |  10 +-
>>  sysdeps/unix/sysv/linux/recvmmsg.c            |  45 ++-
>>  sysdeps/unix/sysv/linux/recvmsg.c             |  34 ++-
>>  .../tst-socket-timestamp-compat-time64.c      |   1 +
>>  .../sysv/linux/tst-socket-timestamp-compat.c  | 265 ++++++++++++++++++
>>  6 files changed, 336 insertions(+), 29 deletions(-)
>>  create mode 100644 sysdeps/unix/sysv/linux/tst-socket-timestamp-compat-time64.c
>>  create mode 100644 sysdeps/unix/sysv/linux/tst-socket-timestamp-compat.c
> 
> Looks okay.
> 
> Reviewed-by: Florian Weimer <fweimer@redhat.com>

OK to push for glibc 2.35. This fixes a blocker for the release.
  

On Fri, Jan 28, 2022 at 9:57 AM Adhemerval Zanella via Libc-alpha
<libc-alpha@sourceware.org> wrote:
>
> 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
> ---
>  include/sys/socket.h                          |  10 +-
>  sysdeps/unix/sysv/linux/Makefile              |  10 +-
>  sysdeps/unix/sysv/linux/recvmmsg.c            |  45 ++-
>  sysdeps/unix/sysv/linux/recvmsg.c             |  34 ++-
>  .../tst-socket-timestamp-compat-time64.c      |   1 +
>  .../sysv/linux/tst-socket-timestamp-compat.c  | 265 ++++++++++++++++++
>  6 files changed, 336 insertions(+), 29 deletions(-)
>  create mode 100644 sysdeps/unix/sysv/linux/tst-socket-timestamp-compat-time64.c
>  create mode 100644 sysdeps/unix/sysv/linux/tst-socket-timestamp-compat.c
>
> diff --git a/include/sys/socket.h b/include/sys/socket.h
> index a1d749f9fa..6e4cf5077f 100644
> --- a/include/sys/socket.h
> +++ b/include/sys/socket.h
> @@ -98,15 +98,21 @@ extern int __sendmmsg (int __fd, struct mmsghdr *__vmessages,
>  libc_hidden_proto (__sendmmsg)
>  #endif
>
> -/* Receive a message as described by MESSAGE from socket FD.
> -   Returns the number of bytes read or -1 for errors.  */
>  extern ssize_t __libc_recvmsg (int __fd, struct msghdr *__message,
>                                int __flags);
>  extern ssize_t __recvmsg (int __fd, struct msghdr *__message,
>                           int __flags) attribute_hidden;
>  #if __TIMESIZE == 64
> +# define __libc_recvmsg64 __libc_recvmsg
> +# define __recvmsg64  __recvmsg
>  # define __recvmmsg64 __recvmmsg
>  #else
> +extern ssize_t __libc_recvmsg64 (int __fd, struct msghdr *__message,
> +                                int __flags);
> +extern ssize_t __recvmsg64 (int __fd, struct msghdr *__message,
> +                           int __flags);
> +/* Receive a message as described by MESSAGE from socket FD.
> +   Returns the number of bytes read or -1 for errors.  */
>  extern int __recvmmsg64 (int __fd, struct mmsghdr *vmessages,
>                          unsigned int vlen, int flags,
>                          struct __timespec64 *timeout);
> diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
> index 4c80ff809c..7122f55975 100644
> --- a/sysdeps/unix/sysv/linux/Makefile
> +++ b/sysdeps/unix/sysv/linux/Makefile
> @@ -277,8 +277,14 @@ sysdep_routines += cmsg_nxthdr
>  CFLAGS-recvmmsg.c = -fexceptions -fasynchronous-unwind-tables
>  CFLAGS-sendmmsg.c = -fexceptions -fasynchronous-unwind-tables
>
> -tests += tst-socket-timestamp
> -tests-time64 += tst-socket-timestamp-time64
> +tests += \
> +  tst-socket-timestamp \
> +  tst-socket-timestamp-compat \
> +  # tests
> +tests-time64 += \
> +  tst-socket-timestamp-time64 \
> +  tst-socket-timestamp-compat-time64
> +  # tests-time64
>
>  tests-special += $(objpfx)tst-socket-consts.out
>  $(objpfx)tst-socket-consts.out: ../sysdeps/unix/sysv/linux/tst-socket-consts.py
> diff --git a/sysdeps/unix/sysv/linux/recvmmsg.c b/sysdeps/unix/sysv/linux/recvmmsg.c
> index 3b9b5f9d1f..1943b9b3d4 100644
> --- a/sysdeps/unix/sysv/linux/recvmmsg.c
> +++ b/sysdeps/unix/sysv/linux/recvmmsg.c
> @@ -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
> @@ -79,10 +93,13 @@ __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);
> -  if (r >= 0 && timeout != NULL)
> -    /* The remanining timeout will be always less the input TIMEOUT.  */
> -    *timeout = valid_timespec64_to_timespec (ts64);
> +  int r = recvmmsg_syscall (fd, vmessages, vlen, flags, pts64);
> +  if (r >= 0)
> +    {
> +      /* The remanining timeout will be always less the input TIMEOUT.  */
> +      if (timeout != NULL)
> +       *timeout = valid_timespec64_to_timespec (ts64);
> +    }
>    return r;
>  }
>  #endif
> diff --git a/sysdeps/unix/sysv/linux/recvmsg.c b/sysdeps/unix/sysv/linux/recvmsg.c
> index 53e567ed31..401d415b2c 100644
> --- a/sysdeps/unix/sysv/linux/recvmsg.c
> +++ b/sysdeps/unix/sysv/linux/recvmsg.c
> @@ -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;
>  }
> -weak_alias (__libc_recvmsg, recvmsg)
> -weak_alias (__libc_recvmsg, __recvmsg)
>  #if __TIMESIZE != 64
> -weak_alias (__recvmsg, __recvmsg64)
> +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)
> diff --git a/sysdeps/unix/sysv/linux/tst-socket-timestamp-compat-time64.c b/sysdeps/unix/sysv/linux/tst-socket-timestamp-compat-time64.c
> new file mode 100644
> index 0000000000..96a0bef0bf
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/tst-socket-timestamp-compat-time64.c
> @@ -0,0 +1 @@
> +#include "tst-socket-timestamp-compat.c"
> diff --git a/sysdeps/unix/sysv/linux/tst-socket-timestamp-compat.c b/sysdeps/unix/sysv/linux/tst-socket-timestamp-compat.c
> new file mode 100644
> index 0000000000..de261dae5a
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/tst-socket-timestamp-compat.c
> @@ -0,0 +1,265 @@
> +/* Check recvmsg/recvmmsg 64-bit timestamp support.
> +   Copyright (C) 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 <arpa/inet.h>
> +#include <string.h>
> +#include <support/check.h>
> +#include <support/xsocket.h>
> +#include <support/xunistd.h>
> +#include <stdbool.h>
> +
> +/* AF_INET socket and address used to receive data.  */
> +static int srv;
> +static struct sockaddr_in srv_addr;
> +
> +static int
> +do_sendto (const struct sockaddr_in *addr, int payload)
> +{
> +  int s = xsocket (AF_INET, SOCK_DGRAM | SOCK_CLOEXEC, 0);
> +  xconnect (s, (const struct sockaddr *) addr, sizeof (*addr));
> +
> +  xsendto (s, &payload, sizeof (payload), 0, (const struct sockaddr *) addr,
> +          sizeof (*addr));
> +
> +  xclose (s);
> +
> +  return 0;
> +}
> +
> +static void
> +do_recvmsg_ancillary (bool use_multi_call, struct mmsghdr *mmhdr,
> +                     void *msgbuf, size_t msgbuflen, int exp_payload)
> +{
> +  int payload;
> +  struct iovec iov =
> +    {
> +      .iov_base = &payload,
> +      .iov_len = sizeof (payload)
> +    };
> +  mmhdr->msg_hdr.msg_name = NULL;
> +  mmhdr->msg_hdr.msg_iov = &iov;
> +  mmhdr->msg_hdr.msg_iovlen = 1;
> +  mmhdr->msg_hdr.msg_control = msgbuf;
> +  mmhdr->msg_hdr.msg_controllen = msgbuflen;
> +
> +  int r;
> +  if (use_multi_call)
> +    {
> +      r = recvmmsg (srv, mmhdr, 1, 0, NULL);
> +      if (r >= 0)
> +       r = mmhdr->msg_len;
> +    }
> +  else
> +    r = recvmsg (srv, &mmhdr->msg_hdr, 0);
> +  TEST_COMPARE (r, sizeof (int));
> +  TEST_COMPARE (payload, exp_payload);
> +}
> +
> +/* Check if recvmsg create the additional 64 bit timestamp if only 32 bit
> +   is enabled for 64 bit recvmsg symbol.  */
> +static void
> +do_test_large_buffer (bool mc)
> +{
> +  struct mmsghdr mmhdr = { 0 };
> +  /* It should be large enought for either timeval/timespec and the
> +     64 time type as well.  */
> +
> +  union
> +  {
> +    struct cmsghdr cmsghdr;
> +    char msgbuf[512];
> +  } control;
> +
> +  /* Enable 32 bit timeval precision and check if no 64 bit timeval stamp
> +     is created.  */
> +  {
> +    int r = setsockopt (srv, SOL_SOCKET, SO_TIMESTAMP_OLD, &(int){1},
> +                       sizeof (int));
> +    TEST_VERIFY_EXIT (r != -1);
> +
> +    do_sendto (&srv_addr, 42);
> +    do_recvmsg_ancillary (mc, &mmhdr, &control, sizeof control, 42);
> +
> +    bool found_timestamp = false;
> +    for (struct cmsghdr *cmsg = CMSG_FIRSTHDR (&mmhdr.msg_hdr);
> +        cmsg != NULL;
> +        cmsg = CMSG_NXTHDR (&mmhdr.msg_hdr, cmsg))
> +    {
> +      if (cmsg->cmsg_level != SOL_SOCKET)
> +       continue;
> +
> +      if (sizeof (time_t) > 4 && cmsg->cmsg_type == SO_TIMESTAMP_NEW)
> +       found_timestamp = true;
> +      else
> +       TEST_VERIFY (cmsg->cmsg_type != SO_TIMESTAMP_NEW);
> +    }
> +
> +    TEST_COMPARE (found_timestamp, sizeof (time_t) > 4);
> +  }
> +
> +  /* Same as before, but for timespec.  */
> +  {
> +    int r = setsockopt (srv, SOL_SOCKET, SO_TIMESTAMPNS_OLD, &(int){1},
> +                       sizeof (int));
> +    TEST_VERIFY_EXIT (r != -1);
> +
> +    do_sendto (&srv_addr, 42);
> +    do_recvmsg_ancillary (mc, &mmhdr, &control, sizeof control, 42);
> +
> +    bool found_timestamp = false;
> +    for (struct cmsghdr *cmsg = CMSG_FIRSTHDR (&mmhdr.msg_hdr);
> +        cmsg != NULL;
> +        cmsg = CMSG_NXTHDR (&mmhdr.msg_hdr, cmsg))
> +    {
> +      if (cmsg->cmsg_level != SOL_SOCKET)
> +       continue;
> +
> +      if (sizeof (time_t) > 4 && cmsg->cmsg_type == SO_TIMESTAMPNS_NEW)
> +       found_timestamp = true;
> +      else
> +       TEST_VERIFY (cmsg->cmsg_type != SO_TIMESTAMPNS_NEW);
> +    }
> +
> +    TEST_COMPARE (found_timestamp, sizeof (time_t) > 4);
> +  }
> +}
> +
> +/* Check if recvmsg does not create the additional 64 bit timestamp if
> +   only 32 bit timestamp is enabled if the ancillary buffer is not large
> +   enought.  Also checks if MSG_CTRUNC is set iff for 64 bit recvmsg
> +   symbol.  */
> +static void
> +do_test_small_buffer (bool mc)
> +{
> +  struct mmsghdr mmhdr = { 0 };
> +
> +  /* Enable 32 bit timeval precision and check if no 64 bit timeval stamp
> +     is created.  */
> +  {
> +    int r = setsockopt (srv, SOL_SOCKET, SO_TIMESTAMP_OLD, &(int){1},
> +                       sizeof (int));
> +    TEST_VERIFY_EXIT (r != -1);
> +
> +    union
> +    {
> +      struct cmsghdr cmsghdr;
> +      char msgbuf[CMSG_SPACE (sizeof (struct timeval))];
> +    } control;
> +
> +    do_sendto (&srv_addr, 42);
> +    do_recvmsg_ancillary (mc, &mmhdr, &control, sizeof control, 42);
> +
> +    bool found_timestamp = false;
> +    for (struct cmsghdr *cmsg = CMSG_FIRSTHDR (&mmhdr.msg_hdr);
> +        cmsg != NULL;
> +        cmsg = CMSG_NXTHDR (&mmhdr.msg_hdr, cmsg))
> +    {
> +      if (cmsg->cmsg_level != SOL_SOCKET)
> +       continue;
> +
> +      if (sizeof (time_t) > 4 && cmsg->cmsg_type == SO_TIMESTAMP_NEW)
> +       found_timestamp = true;
> +      else
> +       TEST_VERIFY (cmsg->cmsg_type != SO_TIMESTAMP_NEW);
> +    }
> +
> +    if (sizeof (time_t) > 4)
> +      {
> +       TEST_VERIFY ((mmhdr.msg_hdr.msg_flags & MSG_CTRUNC));
> +       TEST_COMPARE (found_timestamp, 0);
> +      }
> +    else
> +      {
> +       TEST_VERIFY (!(mmhdr.msg_hdr.msg_flags & MSG_CTRUNC));
> +       TEST_COMPARE (found_timestamp, 0);
> +      }
> +  }
> +
> +  /* Same as before, but for timespec.  */
> +  {
> +    int r = setsockopt (srv, SOL_SOCKET, SO_TIMESTAMPNS_OLD, &(int){1},
> +                       sizeof (int));
> +    TEST_VERIFY_EXIT (r != -1);
> +
> +    union
> +    {
> +      struct cmsghdr cmsghdr;
> +      char msgbuf[CMSG_SPACE (sizeof (struct timespec))];
> +    } control;
> +
> +    do_sendto (&srv_addr, 42);
> +    do_recvmsg_ancillary (mc, &mmhdr, &control, sizeof control, 42);
> +
> +    bool found_timestamp = false;
> +    for (struct cmsghdr *cmsg = CMSG_FIRSTHDR (&mmhdr.msg_hdr);
> +        cmsg != NULL;
> +        cmsg = CMSG_NXTHDR (&mmhdr.msg_hdr, cmsg))
> +    {
> +      if (cmsg->cmsg_level != SOL_SOCKET)
> +       continue;
> +
> +      if (sizeof (time_t) > 4 && cmsg->cmsg_type == SO_TIMESTAMPNS_NEW)
> +       found_timestamp = true;
> +      else
> +       TEST_VERIFY (cmsg->cmsg_type != SO_TIMESTAMPNS_NEW);
> +    }
> +
> +    if (sizeof (time_t) > 4)
> +      {
> +       TEST_VERIFY ((mmhdr.msg_hdr.msg_flags & MSG_CTRUNC));
> +       TEST_COMPARE (found_timestamp, 0);
> +      }
> +    else
> +      {
> +       TEST_VERIFY ((mmhdr.msg_hdr.msg_flags & MSG_CTRUNC) == 0);
> +       TEST_COMPARE (found_timestamp, 0);
> +      }
> +  }
> +}
> +
> +static int
> +do_test (void)
> +{
> +  /* This test only make sense for ABIs that support 32 bit time_t socket
> +     timestampss.  */
> +  if (sizeof (time_t) > 4 && __WORDSIZE == 64)

This is wrong for x32 which has 64-bit time_t from day one, but __WORDSIZE
is 32.

> +    return 0;
> +
> +  srv = xsocket (AF_INET, SOCK_DGRAM, 0);
> +  srv_addr = (struct sockaddr_in) {
> +    .sin_family = AF_INET,
> +    .sin_addr = {.s_addr = htonl (INADDR_LOOPBACK) },
> +  };
> +  xbind (srv, (struct sockaddr *) &srv_addr, sizeof (srv_addr));
> +  {
> +    socklen_t sa_len = sizeof (srv_addr);
> +    xgetsockname (srv, (struct sockaddr *) &srv_addr, &sa_len);
> +    TEST_VERIFY (sa_len == sizeof (srv_addr));
> +  }
> +
> +  /* Check recvmsg;  */
> +  do_test_large_buffer (false);
> +  do_test_small_buffer (false);
> +  /* Check recvmmsg.  */
> +  do_test_large_buffer (true);
> +  do_test_small_buffer (true);
> +
> +  return 0;
> +}
> +
> +#include <support/test-driver.c>
> --
> 2.32.0
>
  

The 01/28/2022 14:50, Adhemerval Zanella via Libc-alpha wrote:
> 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


i think this can cause a build issue on 32bit timesize targets:

https://sourceware.org/bugzilla/show_bug.cgi?id=28860
  

On 03/02/2022 15:34, Szabolcs Nagy wrote:
> The 01/28/2022 14:50, Adhemerval Zanella via Libc-alpha wrote:
>> 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
> 
> 
> i think this can cause a build issue on 32bit timesize targets:
> 
> https://sourceware.org/bugzilla/show_bug.cgi?id=28860

Yeah, I will fix it (the __convert_scm_timestamps should be always
be built now instead of just for __ASSUME_TIME64_SYSCALLS).