[v4] elf: Add tst-ldconfig-bad-aux-cache test [BZ #18093]

  From: Alexandra Hájková <ahajkova@redhat.com>

This test corrupts /var/cache/ldconfig/aux-cache and executes ldconfig
to check it will not segfault using the corrupted aux_cache. The test
uses the test-in-container framework. Verified no regressions on
x86_64.

2019-05-16 Alexandra Hajkova  <ahajkova@redhat.com>

       * elf/Makefile (test-container): Add tst-ldconfig-bad-aux-cache.
       * elf/tst-ldconfig-bad-aux-cache.c: New file.
       * elf/tst-ldconfig_aux-cache.root: New directory.
       * elf/tst-ldconfig-bad-aux-cache.root/postclean.req: New file

 v4
 - use xstat instead of stat
 - remove redundant returns after FAIL_EXIT1
 - remove redundant if (pid) after else
 - use support_install_rootsbindir variable to determine the path to
   ldconfig
 - fix spacing
---
 elf/Makefile                                  |   3 +
 elf/tst-ldconfig-bad-aux-cache.c              | 123 ++++++++++++++++++
 .../postclean.req                             |   0
 3 files changed, 126 insertions(+)
 create mode 100644 elf/tst-ldconfig-bad-aux-cache.c
 create mode 100644 elf/tst-ldconfig-bad-aux-cache.root/postclean.req

diff --git a/elf/tst-ldconfig-bad-aux-cache.root/postclean.req b/elf/tst-ldconfig-bad-aux-cache.root/postclean.req
new file mode 100644
index 0000000000..e69de29bb2
  

On 5/16/19 2:51 PM, Alexandra Hájková wrote:
> From: Alexandra Hájková <ahajkova@redhat.com>
> 
> This test corrupts /var/cache/ldconfig/aux-cache and executes ldconfig
> to check it will not segfault using the corrupted aux_cache. The test
> uses the test-in-container framework. Verified no regressions on
> x86_64.
> 
> 2019-05-16 Alexandra Hajkova  <ahajkova@redhat.com>
> 
>        * elf/Makefile (test-container): Add tst-ldconfig-bad-aux-cache.
>        * elf/tst-ldconfig-bad-aux-cache.c: New file.
>        * elf/tst-ldconfig_aux-cache.root: New directory.
>        * elf/tst-ldconfig-bad-aux-cache.root/postclean.req: New file
> 

Thank you for this update!

I think we need to get rid of the static prog char array given that
support_install_rootstbindir might be any size.

Please post v5.

>  v4
>  - use xstat instead of stat
>  - remove redundant returns after FAIL_EXIT1
>  - remove redundant if (pid) after else
>  - use support_install_rootsbindir variable to determine the path to
>    ldconfig
>  - fix spacing
> ---
>  elf/Makefile                                  |   3 +
>  elf/tst-ldconfig-bad-aux-cache.c              | 123 ++++++++++++++++++
>  .../postclean.req                             |   0
>  3 files changed, 126 insertions(+)
>  create mode 100644 elf/tst-ldconfig-bad-aux-cache.c
>  create mode 100644 elf/tst-ldconfig-bad-aux-cache.root/postclean.req
> 
> diff --git a/elf/Makefile b/elf/Makefile
> index 4895489208..08e2f999bf 100644
> --- a/elf/Makefile
> +++ b/elf/Makefile
> @@ -156,6 +156,9 @@ tests-static-internal := tst-tls1-static tst-tls2-static \
>  CRT-tst-tls1-static-non-pie := $(csu-objpfx)crt1.o
>  tst-tls1-static-non-pie-no-pie = yes
>  
> +tests-container = \
> +			  tst-ldconfig-bad-aux-cache

OK.

> +
>  tests := tst-tls9 tst-leaks1 \
>  	tst-array1 tst-array2 tst-array3 tst-array4 tst-array5 \
>  	tst-auxv
> diff --git a/elf/tst-ldconfig-bad-aux-cache.c b/elf/tst-ldconfig-bad-aux-cache.c
> new file mode 100644
> index 0000000000..7e6c81b73a
> --- /dev/null
> +++ b/elf/tst-ldconfig-bad-aux-cache.c
> @@ -0,0 +1,123 @@
> +/* Test ldconfig does not segfault when aux-cache is corrupted (Bug 18093).

OK.

> +   Copyright (C) 2019 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; see the file COPYING.LIB.  If
> +   not, see <http://www.gnu.org/licenses/>.  */
> +
> +/* This test does the following:
> +   Run ldconfig to create the caches.
> +   Corrupt the caches.
> +   Run ldconfig again.
> +   At each step we verify that ldconfig does not crash.  */

OK.

> +
> +#include <stdio.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <errno.h>
> +#include <sys/wait.h>
> +#include <ftw.h>
> +#include <stdint.h>
> +
> +#include <support/check.h>
> +#include <support/support.h>
> +#include <support/xunistd.h>
> +
> +#include <dirent.h>
> +
> +static int
> +display_info (const char *fpath, const struct stat *sb,
> +              int tflag, struct FTW *ftwbuf)
> +{
> +  printf ("%-3s %2d %7jd   %-40s %d %s\n",
> +          (tflag == FTW_D) ? "d" : (tflag == FTW_DNR) ? "dnr" :
> +          (tflag == FTW_DP) ? "dp" : (tflag == FTW_F) ? "f" :
> +          (tflag == FTW_NS) ? "ns" : (tflag == FTW_SL) ? "sl" :
> +          (tflag == FTW_SLN) ? "sln" : "???",
> +          ftwbuf->level, (intmax_t) sb->st_size,
> +          fpath, ftwbuf->base, fpath + ftwbuf->base);
> +  /* To tell nftw to continue.  */
> +  return 0;
> +}

OK.

> +
> +/* Run ldconfig with a corrupt aux-cache, in particular we test for size
> +   truncation that might happen if a previous ldconfig run failed or if
> +   there were storage or power issues while we were writing the file.
> +   We want ldconfig not to crash, and it should be able to do so by
> +   computing the expected size of the file (bug 18093).  */
> +static int
> +do_test (void)
> +{
> +  char prog[30];

With the variable support_install_rootsbindir we don't want a fixed buffer
size here.

> +  char *const args[] = { prog, NULL };

Will need to drop const so you can write to args.

> +  const char *path = "/var/cache/ldconfig/aux-cache";
> +  struct stat64 fs;
> +  long int size, new_size, i;
> +  int status;
> +  pid_t pid;
> +
> +  /* Create the needed directories. */
> +  xmkdirp ("/var/cache/ldconfig", 0777);
> +  snprintf (prog, sizeof (prog), "%s/ldconfig", support_install_rootsbindir);

Should be:

char *prog = xasprintf ("%s/ldconfig", support_install_rootsbindir);
args[0] = prog;

> +
> +  pid = xfork ();
> +  /* Run ldconfig fist to generate the aux-cache.  */
> +  if (pid == 0)
> +    {
> +      execv (args[0], args);
> +      _exit (1);
> +    }
> +  else
> +    {
> +      xwaitpid (pid, &status, 0);
> +      if (!(WIFEXITED (status)))
> +        FAIL_EXIT1 ("ldconfig was aborted");
> +      xstat (path, &fs);
> +
> +      size = fs.st_size;
> +      /* Run 3 tests, each truncating aux-cache shorter and shorter.  */
> +      for (i = 3; i > 0; i--)
> +        {
> +          new_size = size * i / 4;
> +          if (truncate (path, new_size))
> +            {
> +                FAIL_EXIT1 ("truncation failed: %m");
> +            }
> +          if (nftw (path, display_info, 1000, 0) == -1)
> +            {
> +              FAIL_EXIT1 ("nftw failed.");
> +            }
> +
> +          pid = xfork ();
> +          /* Verify that ldconfig can run with a truncated
> +             aux-cache and doesn't crash.  */
> +          if (pid == 0)
> +            {
> +              execv (args[0], args);
> +              _exit (1);
> +            }
> +          else
> +            {
> +              xwaitpid (pid, &status, 0);
> +              if (!(WIFEXITED (status)))
> +                FAIL_EXIT1 ("ldconfig exited with non-zero status");
> +            }
> +
> +        }
> +    }
> +

free (prog);

> +  return 0;
> +}
> +
> +#include <support/test-driver.c>
> diff --git a/elf/tst-ldconfig-bad-aux-cache.root/postclean.req b/elf/tst-ldconfig-bad-aux-cache.root/postclean.req
> new file mode 100644
> index 0000000000..e69de29bb2
>