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

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

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>
>>>