Re: [PATCH v2 1/2] sysvipc: Fix IPC_INFO and SHM_INFO handling [BZ #26636]

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

If no one opposes I will commit this shortly.

On 05/10/2020 14:11, Adhemerval Zanella wrote:
> Changes from previous version:
> 
>   - Read the shm /proc tunables as 64-bit values to handle 32-bit
>     binaries running on 64-bit kernels.
>   - Handle shmmax value larger than INT_MAX.
>   - Move SHM_STAT_ANY prior SHM_STAT to avoid the test finish early.
> 
> --
> 
> Both commands are Linux extensions where the third argument is either
> a 'struct shminfo' (IPC_INFO) or a 'struct shm_info' (SHM_INFO) instead
> of 'struct shmid_ds'.  And their information does not contain any time
> related fields, so there is no need to extra conversion for __IPC_TIME64.
> 
> The regression testcase checks for Linux specifix SysV ipc message
> control extension.  For SHM_INFO it tries to match the values against the
> tunable /proc values and for MSG_STAT/MSG_STAT_ANY it check if the create\
> shared memory is within the global list returned by the kernel.
> 
> Checked on x86_64-linux-gnu and on i686-linux-gnu (Linux v5.4 and on
> Linux v4.15).
> ---
>  sysdeps/unix/sysv/linux/Makefile            |   2 +-
>  sysdeps/unix/sysv/linux/shmctl.c            |  24 ++-
>  sysdeps/unix/sysv/linux/tst-sysvshm-linux.c | 184 ++++++++++++++++++++
>  3 files changed, 203 insertions(+), 7 deletions(-)
>  create mode 100644 sysdeps/unix/sysv/linux/tst-sysvshm-linux.c
> 
> diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
> index a54eb75d74..5a78614457 100644
> --- a/sysdeps/unix/sysv/linux/Makefile
> +++ b/sysdeps/unix/sysv/linux/Makefile
> @@ -101,7 +101,7 @@ tests += tst-clone tst-clone2 tst-clone3 tst-fanotify tst-personality \
>  	 tst-quota tst-sync_file_range tst-sysconf-iov_max tst-ttyname \
>  	 test-errno-linux tst-memfd_create tst-mlock2 tst-pkey \
>  	 tst-rlimit-infinity tst-ofdlocks tst-gettid tst-gettid-kill \
> -	 tst-tgkill tst-sysvsem-linux tst-sysvmsg-linux
> +	 tst-tgkill tst-sysvsem-linux tst-sysvmsg-linux tst-sysvshm-linux
>  tests-internal += tst-ofdlocks-compat tst-sigcontext-get_pc
>  
>  CFLAGS-tst-sigcontext-get_pc.c = -fasynchronous-unwind-tables
> diff --git a/sysdeps/unix/sysv/linux/shmctl.c b/sysdeps/unix/sysv/linux/shmctl.c
> index 76d88441f1..1d19a798b1 100644
> --- a/sysdeps/unix/sysv/linux/shmctl.c
> +++ b/sysdeps/unix/sysv/linux/shmctl.c
> @@ -90,8 +90,15 @@ __shmctl64 (int shmid, int cmd, struct __shmid64_ds *buf)
>    struct kernel_shmid64_ds kshmid, *arg = NULL;
>    if (buf != NULL)
>      {
> -      shmid64_to_kshmid64 (buf, &kshmid);
> -      arg = &kshmid;
> +      /* This is a Linux extension where kernel expects either a
> +	 'struct shminfo' (IPC_INFO) or 'struct shm_info' (SHM_INFO).  */
> +      if (cmd == IPC_INFO || cmd == SHM_INFO)
> +	arg = (struct kernel_shmid64_ds *) buf;
> +      else
> +	{
> +	  shmid64_to_kshmid64 (buf, &kshmid);
> +	  arg = &kshmid;
> +	}
>      }
>  # ifdef __ASSUME_SYSVIPC_BROKEN_MODE_T
>    if (cmd == IPC_SET)
> @@ -107,7 +114,6 @@ __shmctl64 (int shmid, int cmd, struct __shmid64_ds *buf)
>  
>    switch (cmd)
>      {
> -      case IPC_INFO:
>        case IPC_STAT:
>        case SHM_STAT:
>        case SHM_STAT_ANY:
> @@ -168,8 +174,15 @@ __shmctl (int shmid, int cmd, struct shmid_ds *buf)
>    struct __shmid64_ds shmid64, *buf64 = NULL;
>    if (buf != NULL)
>      {
> -      shmid_to_shmid64 (&shmid64, buf);
> -      buf64 = &shmid64;
> +      /* This is a Linux extension where kernel expects either a
> +	 'struct shminfo' (IPC_INFO) or 'struct shm_info' (SHM_INFO).  */
> +      if (cmd == IPC_INFO || cmd == SHM_INFO)
> +	buf64 = (struct __shmid64_ds *) buf;
> +      else
> +	{
> +	  shmid_to_shmid64 (&shmid64, buf);
> +	  buf64 = &shmid64;
> +	}
>      }
>  
>    int ret = __shmctl64 (shmid, cmd, buf64);
> @@ -178,7 +191,6 @@ __shmctl (int shmid, int cmd, struct shmid_ds *buf)
>  
>    switch (cmd)
>      {
> -      case IPC_INFO:
>        case IPC_STAT:
>        case SHM_STAT:
>        case SHM_STAT_ANY:
> diff --git a/sysdeps/unix/sysv/linux/tst-sysvshm-linux.c b/sysdeps/unix/sysv/linux/tst-sysvshm-linux.c
> new file mode 100644
> index 0000000000..1a6f389d64
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/tst-sysvshm-linux.c
> @@ -0,0 +1,184 @@
> +/* Basic tests for Linux SYSV shared memory extensions.
> +   Copyright (C) 2020 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 <sys/ipc.h>
> +#include <sys/shm.h>
> +#include <errno.h>
> +#include <stdlib.h>
> +#include <stdbool.h>
> +#include <stdio.h>
> +#include <unistd.h>
> +#include <inttypes.h>
> +#include <limits.h>
> +
> +#include <support/check.h>
> +#include <support/temp_file.h>
> +
> +#define SHM_MODE 0644
> +
> +/* These are for the temporary file we generate.  */
> +static char *name;
> +static int shmid;
> +static long int pgsz;
> +
> +static void
> +remove_shm (void)
> +{
> +  /* Enforce message queue removal in case of early test failure.
> +     Ignore error since the shm may already have being removed.  */
> +  shmctl (shmid, IPC_RMID, NULL);
> +}
> +
> +static void
> +do_prepare (int argc, char *argv[])
> +{
> +  TEST_VERIFY_EXIT (create_temp_file ("tst-sysvshm.", &name) != -1);
> +}
> +
> +#define PREPARE do_prepare
> +
> +struct test_shminfo
> +{
> +  unsigned long int shmall;
> +  unsigned long int shmmax;
> +  unsigned long int shmmni;
> +};
> +
> +/* It tries to obtain some system-wide SysV shared memory information from
> +   /proc to check against IPC_INFO/SHM_INFO.  The /proc only returns the
> +   tunables value of SHMALL, SHMMAX, and SHMMNI.  */
> +
> +static uint64_t
> +read_proc_file (const char *file)
> +{
> +  FILE *f = fopen (file, "r");
> +  if (f == NULL)
> +    FAIL_UNSUPPORTED ("/proc is not mounted or %s is not available", file);
> +
> +  /* Handle 32-bit binaries running on 64-bit kernels.  */
> +  uint64_t v;
> +  int r = fscanf (f, "%" SCNu64, &v);
> +  TEST_VERIFY_EXIT (r == 1);
> +
> +  fclose (f);
> +  return v;
> +}
> +
> +
> +/* Check if the message queue with IDX (index into the kernel's internal
> +   array) matches the one with KEY.  The CMD is either SHM_STAT or
> +   SHM_STAT_ANY.  */
> +
> +static bool
> +check_shminfo (int idx, key_t key, int cmd)
> +{
> +  struct shmid_ds shminfo;
> +  int sid = shmctl (idx, cmd, &shminfo);
> +  /* Ignore unused array slot returned by the kernel or information from
> +     unknown message queue.  */
> +  if ((sid == -1 && errno == EINVAL) || sid != shmid)
> +    return false;
> +
> +  if (sid == -1)
> +    FAIL_EXIT1 ("shmctl with %s failed: %m",
> +		cmd == SHM_STAT ? "SHM_STAT" : "SHM_STAT_ANY");
> +
> +  TEST_COMPARE (shminfo.shm_perm.__key, key);
> +  TEST_COMPARE (shminfo.shm_perm.mode, SHM_MODE);
> +  TEST_COMPARE (shminfo.shm_segsz, pgsz);
> +
> +  return true;
> +}
> +
> +static int
> +do_test (void)
> +{
> +  atexit (remove_shm);
> +
> +  pgsz = sysconf (_SC_PAGESIZE);
> +  if (pgsz == -1)
> +    FAIL_EXIT1 ("sysconf (_SC_PAGESIZE) failed: %m");
> +
> +  key_t key = ftok (name, 'G');
> +  if (key == -1)
> +    FAIL_EXIT1 ("ftok failed: %m");
> +
> +  shmid = shmget (key, pgsz, IPC_CREAT | IPC_EXCL | SHM_MODE);
> +  if (shmid == -1)
> +    FAIL_EXIT1 ("shmget failed: %m");
> +
> +  struct test_shminfo tipcinfo;
> +  {
> +    uint64_t v = read_proc_file ("/proc/sys/kernel/shmmax");
> +#if LONG_MAX == INT_MAX
> +    /* Kernel explicit clamp the value for shmmax on compat symbol (32-bit
> +       binaries running on 64-bit kernels).  */
> +    if (v > INT_MAX)
> +      v = INT_MAX;
> +#endif
> +    tipcinfo.shmmax = v;
> +  }
> +  tipcinfo.shmall = read_proc_file ("/proc/sys/kernel/shmall");
> +  tipcinfo.shmmni = read_proc_file ("/proc/sys/kernel/shmmni");
> +
> +  int shmidx;
> +
> +  /* Note: SHM_INFO does not return a shminfo, but rather a 'struct shm_info'
> +     and it is tricky to verify it since it returns system resources consumed
> +     by shared memory.  The shmctl implementation handles SHM_INFO as
> +     IPC_INFO, so the IPC_INFO test should validate SHM_INFO as well.  */
> +
> +  {
> +    struct shminfo ipcinfo;
> +    shmidx = shmctl (shmid, IPC_INFO, (struct shmid_ds *) &ipcinfo);
> +    if (shmidx == -1)
> +      FAIL_EXIT1 ("shmctl with IPC_INFO failed: %m");
> +
> +    TEST_COMPARE (ipcinfo.shmall, tipcinfo.shmall);
> +    TEST_COMPARE (ipcinfo.shmmax, tipcinfo.shmmax);
> +    TEST_COMPARE (ipcinfo.shmmni, tipcinfo.shmmni);
> +  }
> +
> +  /* We check if the created shared memory shows in the global list.  */
> +  bool found = false;
> +  for (int i = 0; i <= shmidx; i++)
> +    {
> +      /* We can't tell apart if SHM_STAT_ANY is not supported (kernel older
> +	 than 4.17) or if the index used is invalid.  So it just check if
> +	 value returned from a valid call matches the created message
> +	 queue.  */
> +      check_shminfo (i, key, SHM_STAT_ANY);
> +
> +      if (check_shminfo (i, key, SHM_STAT))
> +	{
> +	  found = true;
> +	  break;
> +	}
> +    }
> +
> +  if (!found)
> +    FAIL_EXIT1 ("shmctl with SHM_STAT/SHM_STAT_ANY could not find the "
> +		"created shared memory");
> +
> +  if (shmctl (shmid, IPC_RMID, NULL) == -1)
> +    FAIL_EXIT1 ("shmctl failed");
> +
> +  return 0;
> +}
> +
> +#include <support/test-driver.c>
>