diff mbox series

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

Message ID 20210928133921.2988530-2-adhemerval.zanella@linaro.org
State Superseded
Headers show
Series [1/2] support: Add support_socket_time64_timestamp | expand

Checks

Context Check Description
dj/TryBot-apply_patch success Patch applied to master at the time it was sent
dj/TryBot-32bit success Build for i686

Commit Message

Adhemerval Zanella Sept. 28, 2021, 1:39 p.m. UTC
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.
---
 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

Comments

Michael Hudson-Doyle Sept. 29, 2021, 1:10 a.m. UTC | #1
I think I experienced this bug while trying to fix systemd-networkd's DHCP6
issues on armhf. But I've lost the test environment now and am not sure I
have the energy to recreate it... Do you plan to backport this to
release/2.34/master?

On Wed, 29 Sept 2021 at 02:40, Adhemerval Zanella via Libc-alpha <
libc-alpha@sourceware.org> wrote:

>
> +
> +/* Check if the extra anciallry space is correctly handled by recvmsg and
>

Typo: ancillary


> +   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)



>
>
+
> +  /* If there is not timestamp in the ancilliary data, recvmsg should set
> +     the flag inidcating it.  */
>

Typo: indicating. Also probably "if there is *no* timestamp" in the
previous line.


> +  if (!timestamp)
> +    TEST_VERIFY (mmhdr.msg_hdr.msg_flags & MSG_TRUNC);
> +  else
> +    TEST_COMPARE (timestamp, true);
> +  TEST_COMPARE (origdstaddr, true);
> +}
>

Cheers,
mwh
Adhemerval Zanella Sept. 29, 2021, 1:30 p.m. UTC | #2
On 28/09/2021 22:10, Michael Hudson-Doyle wrote:
> I think I experienced this bug while trying to fix systemd-networkd's DHCP6 issues on armhf. But I've lost the test environment now and am not sure I have the energy to recreate it... Do you plan to backport this to release/2.34/master?

Yes.

> 
> On Wed, 29 Sept 2021 at 02:40, Adhemerval Zanella via Libc-alpha <libc-alpha@sourceware.org <mailto:libc-alpha@sourceware.org>> wrote:
> 
> 
>     +
>     +/* Check if the extra anciallry space is correctly handled by recvmsg and
> 
> 
> Typo: ancillary

Ack.

>  
> 
>     +   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)
> 
>  
> 
>      
> 
>     +
>     +  /* If there is not timestamp in the ancilliary data, recvmsg should set
>     +     the flag inidcating it.  */
> 
> 
> Typo: indicating. Also probably "if there is *no* timestamp" in the previous line.

Ack.

>  
> 
>     +  if (!timestamp)
>     +    TEST_VERIFY (mmhdr.msg_hdr.msg_flags & MSG_TRUNC);
>     +  else
>     +    TEST_COMPARE (timestamp, true);
>     +  TEST_COMPARE (origdstaddr, true);
>     +}
> 
> 
> Cheers,
> mwh
diff mbox series

Patch

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..152325a43c
--- /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 anciallry 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 not timestamp in the ancilliary data, recvmsg should set
+     the flag inidcating 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_time64_timestamp (srv);
+
+  do_test_slack_space ();
+  do_test_multiple_ancillary ();
+
+  xclose (srv);
+
+  return 0;
+}
+
+#include <support/test-driver.c>