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tst-env-setuid: Use support_capture_subprogram_self_sgid

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Use the support_capture_subprogram_self_sgid to spawn an sgid child.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>

(cherry picked from commit ca33528106)
This commit is contained in:
Siddhesh Poyarekar 2021-03-16 12:37:53 +05:30
parent 2c23a4d7e0
commit 1927d02d19
1 changed files with 14 additions and 183 deletions
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193
elf/tst-env-setuid.c
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@ -29,173 +29,12 @@
#include <sys/wait.h>
#include <unistd.h>
#include <support/check.h>
#include <support/support.h>
#include <support/test-driver.h>
#include <support/capture_subprocess.h>
static char SETGID_CHILD[] = "setgid-child";
#define CHILD_STATUS 42
/* Return a GID which is not our current GID, but is present in the
supplementary group list. */
static gid_t
choose_gid (void)
{
const int count = 64;
gid_t groups[count];
int ret = getgroups (count, groups);
if (ret < 0)
{
printf ("getgroups: %m\n");
exit (1);
}
gid_t current = getgid ();
for (int i = 0; i < ret; ++i)
{
if (groups[i] != current)
return groups[i];
}
return 0;
}
/* Spawn and execute a program and verify that it returns the CHILD_STATUS. */
static pid_t
do_execve (char **args)
{
pid_t kid = vfork ();
if (kid < 0)
{
printf ("vfork: %m\n");
return -1;
}
if (kid == 0)
{
/* Child process. */
execve (args[0], args, environ);
_exit (-errno);
}
if (kid < 0)
return 1;
int status;
if (waitpid (kid, &status, 0) < 0)
{
printf ("waitpid: %m\n");
return 1;
}
if (WEXITSTATUS (status) == EXIT_UNSUPPORTED)
return EXIT_UNSUPPORTED;
if (!WIFEXITED (status) || WEXITSTATUS (status) != CHILD_STATUS)
{
printf ("Unexpected exit status %d from child process\n",
WEXITSTATUS (status));
return 1;
}
return 0;
}
/* Copies the executable into a restricted directory, so that we can
safely make it SGID with the TARGET group ID. Then runs the
executable. */
static int
run_executable_sgid (gid_t target)
{
char *dirname = xasprintf ("%s/tst-tunables-setuid.%jd",
test_dir, (intmax_t) getpid ());
char *execname = xasprintf ("%s/bin", dirname);
int infd = -1;
int outfd = -1;
int ret = 0;
if (mkdir (dirname, 0700) < 0)
{
printf ("mkdir: %m\n");
goto err;
}
infd = open ("/proc/self/exe", O_RDONLY);
if (infd < 0)
{
printf ("open (/proc/self/exe): %m\n");
goto err;
}
outfd = open (execname, O_WRONLY | O_CREAT | O_EXCL, 0700);
if (outfd < 0)
{
printf ("open (%s): %m\n", execname);
goto err;
}
char buf[4096];
for (;;)
{
ssize_t rdcount = read (infd, buf, sizeof (buf));
if (rdcount < 0)
{
printf ("read: %m\n");
goto err;
}
if (rdcount == 0)
break;
char *p = buf;
char *end = buf + rdcount;
while (p != end)
{
ssize_t wrcount = write (outfd, buf, end - p);
if (wrcount == 0)
errno = ENOSPC;
if (wrcount <= 0)
{
printf ("write: %m\n");
goto err;
}
p += wrcount;
}
}
if (fchown (outfd, getuid (), target) < 0)
{
printf ("fchown (%s): %m\n", execname);
goto err;
}
if (fchmod (outfd, 02750) < 0)
{
printf ("fchmod (%s): %m\n", execname);
goto err;
}
if (close (outfd) < 0)
{
printf ("close (outfd): %m\n");
goto err;
}
if (close (infd) < 0)
{
printf ("close (infd): %m\n");
goto err;
}
char *args[] = {execname, SETGID_CHILD, NULL};
ret = do_execve (args);
err:
if (outfd >= 0)
close (outfd);
if (infd >= 0)
close (infd);
if (execname)
{
unlink (execname);
free (execname);
}
if (dirname)
{
rmdir (dirname);
free (dirname);
}
return ret;
}
#ifndef test_child
static int
@ -256,40 +95,32 @@ do_test (int argc, char **argv)
if (argc == 2 && strcmp (argv[1], SETGID_CHILD) == 0)
{
if (getgid () == getegid ())
{
/* This can happen if the file system is mounted nosuid. */
fprintf (stderr, "SGID failed: GID and EGID match (%jd)\n",
FAIL_UNSUPPORTED ("SGID failed: GID and EGID match (%jd)\n",
(intmax_t) getgid ());
exit (EXIT_UNSUPPORTED);
}
int ret = test_child ();
if (ret != 0)
exit (1);
exit (CHILD_STATUS);
exit (EXIT_SUCCESS);
}
else
{
if (test_parent () != 0)
exit (1);
/* Try running a setgid program. */
gid_t target = choose_gid ();
if (target == 0)
{
fprintf (stderr,
"Could not find a suitable GID for user %jd, skipping test\n",
(intmax_t) getuid ());
exit (0);
}
int status = support_capture_subprogram_self_sgid (SETGID_CHILD);
return run_executable_sgid (target);
}
if (WEXITSTATUS (status) == EXIT_UNSUPPORTED)
return EXIT_UNSUPPORTED;
/* Something went wrong and our argv was corrupted. */
_exit (1);
if (!WIFEXITED (status))
FAIL_EXIT1 ("Unexpected exit status %d from child process\n", status);
return 0;
}
}
#define TEST_FUNCTION_ARGV do_test