Re: [PATCH v2 2/2] linux: Fix ancillary 64-bit time timestamp conversion (BZ #28349, BZ #28350)

[Adhemerval Zanella <adhemerval.zanella@linaro.org>]

Ping (x4), this seems to be an important fix for 64-bit time_t.

On 08/11/2021 15:30, Adhemerval Zanella wrote:
> Ping (x3).
> 
> On 20/10/2021 09:08, Adhemerval Zanella wrote:
>> Ping (x2).
>>
>> On 08/10/2021 08:58, Adhemerval Zanella wrote:
>>> Ping.
>>>
>>> On 29/09/2021 11:06, Adhemerval Zanella wrote:
>>>> The __convert_scm_timestamps() only updates the control message last
>>>> pointer for SOL_SOCKET type, so if the message control buffer contains
>>>> multiple ancillary message types the converted timestamp one might
>>>> overwrite a valid message.
>>>>
>>>> The test check if the extra ancillary space is correctly handled
>>>> by recvmsg/recvmmsg, where if there is no extra space for the 64-bit
>>>> time_t converted message the control buffer should be marked with
>>>> MSG_TRUNC.  It also check if recvmsg/recvmmsg handle correctly multiple
>>>> ancillary data.
>>>>
>>>> Checked on x86_64-linux and on i686-linux-gnu on both 5.11 and
>>>> 4.15 kernel.
>>>>
>>>> ---
>>>> v2: Fix some typos and use support_socket_time64_timestamp.
>>>>
>>>> ---
>>>>  sysdeps/unix/sysv/linux/Makefile              |   3 +
>>>>  .../unix/sysv/linux/convert_scm_timestamps.c  |  40 +--
>>>>  .../sysv/linux/tst-socket-timestamp-time64.c  |   1 +
>>>>  .../unix/sysv/linux/tst-socket-timestamp.c    | 338 ++++++++++++++++++
>>>>  4 files changed, 362 insertions(+), 20 deletions(-)
>>>>  create mode 100644 sysdeps/unix/sysv/linux/tst-socket-timestamp-time64.c
>>>>  create mode 100644 sysdeps/unix/sysv/linux/tst-socket-timestamp.c
>>>>
>>>> diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
>>>> index 76ad06361c..3399c87468 100644
>>>> --- a/sysdeps/unix/sysv/linux/Makefile
>>>> +++ b/sysdeps/unix/sysv/linux/Makefile
>>>> @@ -262,6 +262,9 @@ 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-special += $(objpfx)tst-socket-consts.out
>>>>  $(objpfx)tst-socket-consts.out: ../sysdeps/unix/sysv/linux/tst-socket-consts.py
>>>>  	PYTHONPATH=../scripts \
>>>> diff --git a/sysdeps/unix/sysv/linux/convert_scm_timestamps.c b/sysdeps/unix/sysv/linux/convert_scm_timestamps.c
>>>> index 00c934c413..5ee930035b 100644
>>>> --- a/sysdeps/unix/sysv/linux/convert_scm_timestamps.c
>>>> +++ b/sysdeps/unix/sysv/linux/convert_scm_timestamps.c
>>>> @@ -54,26 +54,26 @@ __convert_scm_timestamps (struct msghdr *msg, socklen_t msgsize)
>>>>         cmsg != NULL;
>>>>         cmsg = CMSG_NXTHDR (msg, cmsg))
>>>>      {
>>>> -      if (cmsg->cmsg_level != SOL_SOCKET)
>>>> -	continue;
>>>> -
>>>> -      switch (cmsg->cmsg_type)
>>>> +      if (cmsg->cmsg_level == SOL_SOCKET)
>>>>  	{
>>>> -	case COMPAT_SO_TIMESTAMP_OLD:
>>>> -	  if (type != 0)
>>>> -	    break;
>>>> -	  type = COMPAT_SO_TIMESTAMP_NEW;
>>>> -	  goto common;
>>>> -
>>>> -	case COMPAT_SO_TIMESTAMPNS_OLD:
>>>> -	  type = COMPAT_SO_TIMESTAMPNS_NEW;
>>>> -
>>>> -	/* fallthrough  */
>>>> -	common:
>>>> -	  memcpy (tmp, CMSG_DATA (cmsg), sizeof (tmp));
>>>> -	  tvts[0] = tmp[0];
>>>> -	  tvts[1] = tmp[1];
>>>> -	  break;
>>>> +	  switch (cmsg->cmsg_type)
>>>> +	    {
>>>> +	    case COMPAT_SO_TIMESTAMP_OLD:
>>>> +	      if (type != 0)
>>>> +		break;
>>>> +	      type = COMPAT_SO_TIMESTAMP_NEW;
>>>> +	      goto common;
>>>> +
>>>> +	    case COMPAT_SO_TIMESTAMPNS_OLD:
>>>> +	      type = COMPAT_SO_TIMESTAMPNS_NEW;
>>>> +
>>>> +	    /* fallthrough  */
>>>> +	    common:
>>>> +	      memcpy (tmp, CMSG_DATA (cmsg), sizeof (tmp));
>>>> +	      tvts[0] = tmp[0];
>>>> +	      tvts[1] = tmp[1];
>>>> +	      break;
>>>> +	    }
>>>>  	}
>>>>  
>>>>        last = cmsg;
>>>> @@ -89,7 +89,7 @@ __convert_scm_timestamps (struct msghdr *msg, socklen_t msgsize)
>>>>      }
>>>>  
>>>>    msg->msg_controllen += CMSG_SPACE (sizeof tvts);
>>>> -  cmsg = CMSG_NXTHDR(msg, last);
>>>> +  cmsg = CMSG_NXTHDR (msg, last);
>>>>    if (cmsg == NULL)
>>>>      return;
>>>>    cmsg->cmsg_level = SOL_SOCKET;
>>>> diff --git a/sysdeps/unix/sysv/linux/tst-socket-timestamp-time64.c b/sysdeps/unix/sysv/linux/tst-socket-timestamp-time64.c
>>>> new file mode 100644
>>>> index 0000000000..ae424c2a70
>>>> --- /dev/null
>>>> +++ b/sysdeps/unix/sysv/linux/tst-socket-timestamp-time64.c
>>>> @@ -0,0 +1 @@
>>>> +#include "tst-socket-timestamp.c"
>>>> diff --git a/sysdeps/unix/sysv/linux/tst-socket-timestamp.c b/sysdeps/unix/sysv/linux/tst-socket-timestamp.c
>>>> new file mode 100644
>>>> index 0000000000..9aaa705054
>>>> --- /dev/null
>>>> +++ b/sysdeps/unix/sysv/linux/tst-socket-timestamp.c
>>>> @@ -0,0 +1,338 @@
>>>> +/* Check recvmsg/recvmmsg 64-bit timestamp support.
>>>> +   Copyright (C) 2021 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 <array_length.h>
>>>> +#include <arpa/inet.h>
>>>> +#include <errno.h>
>>>> +#include <string.h>
>>>> +#include <stdio.h>
>>>> +#include <support/check.h>
>>>> +#include <support/next_to_fault.h>
>>>> +#include <support/support.h>
>>>> +#include <support/test-driver.h>
>>>> +#include <support/xunistd.h>
>>>> +#include <support/xsocket.h>
>>>> +#include <sys/mman.h>
>>>> +
>>>> +/* Some extra space added for ancillary data, it might be used to convert
>>>> +   32-bit timestamp to 64-bit for _TIME_BITS=64.  */
>>>> +enum { slack_max_size = 64 };
>>>> +static const int slack[] = { 0, 4, 8, 16, 32, slack_max_size };
>>>> +
>>>> +static bool support_64_timestamp;
>>>> +/* AF_INET socket and address used to send and receive data.  */
>>>> +static int srv;
>>>> +static struct sockaddr_in srv_addr;
>>>> +
>>>> +static int
>>>> +do_sendto (const struct sockaddr_in *addr, int nmsgs)
>>>> +{
>>>> +  int s = xsocket (AF_INET, SOCK_DGRAM | SOCK_CLOEXEC, 0);
>>>> +  xconnect (s, (const struct sockaddr *) addr, sizeof (*addr));
>>>> +
>>>> +  for (int i = 0; i < nmsgs; i++)
>>>> +    xsendto (s, &i, sizeof (i), 0, (const struct sockaddr *) addr,
>>>> +	     sizeof (*addr));
>>>> +
>>>> +  return 0;
>>>> +}
>>>> +
>>>> +static void
>>>> +do_recvmsg_slack_ancillary (bool use_multi_call, int s, void *cmsg,
>>>> +			    size_t slack, size_t tsize, int exp_msg)
>>>> +{
>>>> +  int msg;
>>>> +  struct iovec iov =
>>>> +    {
>>>> +      .iov_base = &msg,
>>>> +      .iov_len = sizeof (msg)
>>>> +    };
>>>> +  size_t msgs = CMSG_SPACE (tsize) + slack;
>>>> +  struct mmsghdr mmhdr =
>>>> +    {
>>>> +      .msg_hdr =
>>>> +      {
>>>> +        .msg_name = NULL,
>>>> +        .msg_namelen = 0,
>>>> +        .msg_iov = &iov,
>>>> +        .msg_iovlen = 1,
>>>> +        .msg_controllen = msgs,
>>>> +        .msg_control = cmsg != NULL ? cmsg - msgs : NULL,
>>>> +      },
>>>> +    };
>>>> +
>>>> +  int r;
>>>> +  if (use_multi_call)
>>>> +    {
>>>> +      r = recvmmsg (s, &mmhdr, 1, 0, NULL);
>>>> +      if (r >= 0)
>>>> +	r = mmhdr.msg_len;
>>>> +    }
>>>> +  else
>>>> +    r = recvmsg (s, &mmhdr.msg_hdr, 0);
>>>> +  TEST_COMPARE (r, sizeof (int));
>>>> +  TEST_COMPARE (msg, exp_msg);
>>>> +
>>>> +  if (cmsg == NULL)
>>>> +    return;
>>>> +
>>>> +  /* A timestamp is expected if 32-bit timestamp are used (support in every
>>>> +     configuration) or if underlying kernel support 64-bit timestamps.
>>>> +     Otherwise recvmsg will need extra space do add the 64-bit timestamp.  */
>>>> +  bool exp_timestamp;
>>>> +  if (sizeof (time_t) == 4 || support_64_timestamp)
>>>> +    exp_timestamp = true;
>>>> +   else
>>>> +    exp_timestamp = slack >= CMSG_SPACE (tsize);
>>>> +
>>>> +  bool 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 (cmsg->cmsg_type == SCM_TIMESTAMP
>>>> +	  && cmsg->cmsg_len == CMSG_LEN (sizeof (struct timeval)))
>>>> +	{
>>>> +	  struct timeval tv;
>>>> +	  memcpy (&tv, CMSG_DATA (cmsg), sizeof (tv));
>>>> +	  if (test_verbose)
>>>> +	    printf ("SCM_TIMESTAMP:   {%jd, %jd}\n", (intmax_t)tv.tv_sec,
>>>> +		    (intmax_t)tv.tv_usec);
>>>> +	  timestamp = true;
>>>> +	}
>>>> +      else if (cmsg->cmsg_type == SCM_TIMESTAMPNS
>>>> +	       && cmsg->cmsg_len == CMSG_LEN (sizeof (struct timespec)))
>>>> +	{
>>>> +	  struct timespec ts;
>>>> +	  memcpy (&ts, CMSG_DATA (cmsg), sizeof (ts));
>>>> +	  if (test_verbose)
>>>> +	    printf ("SCM_TIMESTAMPNS: {%jd, %jd}\n", (intmax_t)ts.tv_sec,
>>>> +		    (intmax_t)ts.tv_nsec);
>>>> +	  timestamp = true;
>>>> +	}
>>>> +    }
>>>> +
>>>> +  /* If there is not timestamp in the ancilliary data, recvmsg should set
>>>> +     the flag inidcating it.  */
>>>> +  if (exp_timestamp && !timestamp)
>>>> +    TEST_VERIFY (mmhdr.msg_hdr.msg_flags & MSG_TRUNC);
>>>> +  else
>>>> +    TEST_COMPARE (timestamp, exp_timestamp);
>>>> +}
>>>> +
>>>> +/* Check if the extra ancillary space is correctly handled by recvmsg and
>>>> +   recvmmsg: if there is no extra space for the 64-bit timestamp the syscall
>>>> +   should set MSG_TRUNC flag, otherwise an extra cmsghdr with the converted
>>>> +   timestamp is appended at the message control buffer.  */
>>>> +static void
>>>> +do_test_slack_space (void)
>>>> +{
>>>> +  /* Setup the ancillary data buffer with an extra page with PROT_NONE to
>>>> +     check the possible timestamp conversion on some systems.  */
>>>> +  struct support_next_to_fault nf =
>>>> +    support_next_to_fault_allocate (slack_max_size);
>>>> +  void *msgbuf = nf.buffer + slack_max_size;
>>>> +
>>>> +  /* Enable the timestamp using struct timeval precision.  */
>>>> +  {
>>>> +    int r = setsockopt (srv, SOL_SOCKET, SO_TIMESTAMP, &(int){1},
>>>> +			sizeof (int));
>>>> +    TEST_VERIFY_EXIT (r != -1);
>>>> +  }
>>>> +  /* Check recvmsg.  */
>>>> +  do_sendto (&srv_addr, array_length (slack));
>>>> +  for (int s = 0; s < array_length (slack); s++)
>>>> +    do_recvmsg_slack_ancillary (false, srv, msgbuf, slack[s],
>>>> +				sizeof (struct timeval), s);
>>>> +  /* Check recvmmsg.  */
>>>> +  do_sendto (&srv_addr, array_length (slack));
>>>> +  for (int s = 0; s < array_length (slack); s++)
>>>> +    do_recvmsg_slack_ancillary (true, srv, msgbuf, slack[s],
>>>> +				sizeof (struct timeval), s);
>>>> +
>>>> +  /* Now enable timestamp using a higher precision, it overwrites the previous
>>>> +     precision.  */
>>>> +  {
>>>> +    int r = setsockopt (srv, SOL_SOCKET, SO_TIMESTAMPNS, &(int){1},
>>>> +			sizeof (int));
>>>> +    TEST_VERIFY_EXIT (r != -1);
>>>> +  }
>>>> +  /* Check recvmsg.  */
>>>> +  do_sendto (&srv_addr, array_length (slack));
>>>> +  for (int s = 0; s < array_length (slack); s++)
>>>> +    do_recvmsg_slack_ancillary (false, srv, msgbuf, slack[s],
>>>> +				sizeof (struct timespec), s);
>>>> +  /* Check recvmmsg.  */
>>>> +  do_sendto (&srv_addr, array_length (slack));
>>>> +  for (int s = 0; s < array_length (slack); s++)
>>>> +    do_recvmsg_slack_ancillary (true, srv, msgbuf, slack[s],
>>>> +				sizeof (struct timespec), s);
>>>> +
>>>> +  support_next_to_fault_free (&nf);
>>>> +}
>>>> +
>>>> +/* Check if the converted 64-bit timestamp is correctly appended when there
>>>> +   are multiple ancillary messages.  */
>>>> +static void
>>>> +do_recvmsg_multiple_ancillary (bool use_multi_call, int s, void *cmsg,
>>>> +			       size_t cmsgsize, int exp_msg)
>>>> +{
>>>> +  int msg;
>>>> +  struct iovec iov =
>>>> +    {
>>>> +      .iov_base = &msg,
>>>> +      .iov_len = sizeof (msg)
>>>> +    };
>>>> +  size_t msgs = cmsgsize;
>>>> +  struct mmsghdr mmhdr =
>>>> +    {
>>>> +      .msg_hdr =
>>>> +      {
>>>> +        .msg_name = NULL,
>>>> +        .msg_namelen = 0,
>>>> +        .msg_iov = &iov,
>>>> +        .msg_iovlen = 1,
>>>> +        .msg_controllen = msgs,
>>>> +        .msg_control = cmsg,
>>>> +      },
>>>> +    };
>>>> +
>>>> +  int r;
>>>> +  if (use_multi_call)
>>>> +    {
>>>> +      r = recvmmsg (s, &mmhdr, 1, 0, NULL);
>>>> +      if (r >= 0)
>>>> +	r = mmhdr.msg_len;
>>>> +    }
>>>> +  else
>>>> +    r = recvmsg (s, &mmhdr.msg_hdr, 0);
>>>> +  TEST_COMPARE (r, sizeof (int));
>>>> +  TEST_COMPARE (msg, exp_msg);
>>>> +
>>>> +  if (cmsg == NULL)
>>>> +    return;
>>>> +
>>>> +  bool timestamp = false;
>>>> +  bool origdstaddr = false;
>>>> +  for (struct cmsghdr *cmsg = CMSG_FIRSTHDR (&mmhdr.msg_hdr);
>>>> +       cmsg != NULL;
>>>> +       cmsg = CMSG_NXTHDR (&mmhdr.msg_hdr, cmsg))
>>>> +    {
>>>> +      if (cmsg->cmsg_level == SOL_IP
>>>> +	  && cmsg->cmsg_type == IP_ORIGDSTADDR
>>>> +	  && cmsg->cmsg_len >= CMSG_LEN (sizeof (struct sockaddr_in)))
>>>> +	{
>>>> +	  struct sockaddr_in sa;
>>>> +	  memcpy (&sa, CMSG_DATA (cmsg), sizeof (sa));
>>>> +	  if (test_verbose)
>>>> +	    {
>>>> +	      char str[INET_ADDRSTRLEN];
>>>> +	      inet_ntop (AF_INET, &sa.sin_addr, str, INET_ADDRSTRLEN);
>>>> +	      printf ("IP_ORIGDSTADDR:  %s:%d\n", str, ntohs (sa.sin_port));
>>>> +	    }
>>>> +	  origdstaddr = sa.sin_addr.s_addr == srv_addr.sin_addr.s_addr
>>>> +			&& sa.sin_port == srv_addr.sin_port;
>>>> +	}
>>>> +      if (cmsg->cmsg_level == SOL_SOCKET
>>>> +	  && cmsg->cmsg_type == SCM_TIMESTAMP
>>>> +	  && cmsg->cmsg_len >= CMSG_LEN (sizeof (struct timeval)))
>>>> +	{
>>>> +	  struct timeval tv;
>>>> +	  memcpy (&tv, CMSG_DATA (cmsg), sizeof (tv));
>>>> +	  if (test_verbose)
>>>> +	    printf ("SCM_TIMESTAMP:   {%jd, %jd}\n", (intmax_t)tv.tv_sec,
>>>> +		    (intmax_t)tv.tv_usec);
>>>> +	  timestamp = true;
>>>> +	}
>>>> +    }
>>>> +
>>>> +  /* If there is no timestamp in the ancillary data, recvmsg should set
>>>> +     the flag to indicate it.  */
>>>> +  if (!timestamp)
>>>> +    TEST_VERIFY (mmhdr.msg_hdr.msg_flags & MSG_TRUNC);
>>>> +  else
>>>> +    TEST_COMPARE (timestamp, true);
>>>> +  TEST_COMPARE (origdstaddr, true);
>>>> +}
>>>> +
>>>> +static void
>>>> +do_test_multiple_ancillary (void)
>>>> +{
>>>> +  {
>>>> +    int r = setsockopt (srv, SOL_SOCKET, SO_TIMESTAMP, &(int){1},
>>>> +			sizeof (int));
>>>> +    TEST_VERIFY_EXIT (r != -1);
>>>> +  }
>>>> +  {
>>>> +    int r = setsockopt (srv, IPPROTO_IP, IP_RECVORIGDSTADDR, &(int){1},
>>>> +			sizeof (int));
>>>> +    TEST_VERIFY_EXIT (r != -1);
>>>> +  }
>>>> +
>>>> +  /* Enougth data for default SO_TIMESTAMP, the IP_RECVORIGDSTADDR, and the
>>>> +     extra 64-bit SO_TIMESTAMP.  */
>>>> +  enum { msgbuflen = CMSG_SPACE (2 * sizeof (uint64_t))
>>>> +		     + CMSG_SPACE (sizeof (struct sockaddr_in))
>>>> +		     + CMSG_SPACE (2 * sizeof (uint64_t)) };
>>>> +  char msgbuf[msgbuflen];
>>>> +
>>>> +  enum { nmsgs = 8 };
>>>> +  /* Check recvmsg.  */
>>>> +  do_sendto (&srv_addr, nmsgs);
>>>> +  for (int s = 0; s < nmsgs; s++)
>>>> +    do_recvmsg_multiple_ancillary (false, srv, msgbuf, msgbuflen, s);
>>>> +  /* Check recvmmsg.  */
>>>> +  do_sendto (&srv_addr, nmsgs);
>>>> +  for (int s = 0; s < nmsgs; s++)
>>>> +    do_recvmsg_multiple_ancillary (true, srv, msgbuf, msgbuflen, s);
>>>> +}
>>>> +
>>>> +static int
>>>> +do_test (void)
>>>> +{
>>>> +  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));
>>>> +  }
>>>> +
>>>> +  TEST_COMPARE (recvmsg (-1, NULL, 0), -1);
>>>> +  TEST_COMPARE (errno, EBADF);
>>>> +  TEST_COMPARE (recvmmsg (-1, NULL, 0, 0, NULL), -1);
>>>> +  TEST_COMPARE (errno, EBADF);
>>>> +
>>>> +  /* If underlying kernel does not support   */
>>>> +  support_64_timestamp = support_socket_so_timestamp_time64 (srv);
>>>> +
>>>> +  do_test_slack_space ();
>>>> +  do_test_multiple_ancillary ();
>>>> +
>>>> +  xclose (srv);
>>>> +
>>>> +  return 0;
>>>> +}
>>>> +
>>>> +#include <support/test-driver.c>
>>>>