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/* Copyright (C) 2012-2020 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/>. */
/* Test that secure_getenv works by invoking the test as a SGID
program with a group ID from the supplementary group list. This
test can fail spuriously if the user is not a member of a suitable
supplementary group. */
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <unistd.h>
#include <support/support.h>
#include <support/test-driver.h>
static char MAGIC_ARGUMENT[] = "run-actual-test";
#define MAGIC_STATUS 19
/* Return a GID which is not our current GID, but is present in the
supplementary group list. */
static gid_t
choose_gid (void)
{
int count = getgroups (0, NULL);
if (count < 0)
{
printf ("getgroups: %m\n");
exit (1);
}
gid_t *groups;
groups = xcalloc (count, sizeof (*groups));
int ret = getgroups (count, groups);
if (ret < 0)
{
printf ("getgroups: %m\n");
exit (1);
}
gid_t current = getgid ();
gid_t not_current = 0;
for (int i = 0; i < ret; ++i)
{
if (groups[i] != current)
{
not_current = groups[i];
break;
}
}
free (groups);
return not_current;
}
/* 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/secure-getenv.%jd",
test_dir, (intmax_t) getpid ());
char *execname = xasprintf ("%s/bin", dirname);
int infd = -1;
int outfd = -1;
int ret = -1;
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;
}
int kid = fork ();
if (kid < 0)
{
printf ("fork: %m\n");
goto err;
}
if (kid == 0)
{
/* Child process. */
char *args[] = { execname, MAGIC_ARGUMENT, NULL };
execve (execname, args, environ);
printf ("execve (%s): %m\n", execname);
_exit (1);
}
int status;
if (waitpid (kid, &status, 0) < 0)
{
printf ("waitpid: %m\n");
goto err;
}
if (!WIFEXITED (status) || WEXITSTATUS (status) != MAGIC_STATUS)
{
printf ("Unexpected exit status %d from child process\n",
status);
goto err;
}
ret = 0;
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;
}
static int
do_test (void)
{
if (getenv ("PATH") == NULL)
{
printf ("PATH not set\n");
exit (1);
}
if (secure_getenv ("PATH") == NULL)
{
printf ("PATH not set according to secure_getenv\n");
exit (1);
}
if (strcmp (getenv ("PATH"), secure_getenv ("PATH")) != 0)
{
printf ("PATH mismatch (%s, %s)\n",
getenv ("PATH"), secure_getenv ("PATH"));
exit (1);
}
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);
}
return run_executable_sgid (target);
}
static void
alternative_main (int argc, char **argv)
{
if (argc == 2 && strcmp (argv[1], MAGIC_ARGUMENT) == 0)
{
if (getgid () == getegid ())
{
/* This can happen if the file system is mounted nosuid. */
fprintf (stderr, "SGID failed: GID and EGID match (%jd)\n",
(intmax_t) getgid ());
exit (MAGIC_STATUS);
}
if (getenv ("PATH") == NULL)
{
printf ("PATH variable not present\n");
exit (3);
}
if (secure_getenv ("PATH") != NULL)
{
printf ("PATH variable not filtered out\n");
exit (4);
}
exit (MAGIC_STATUS);
}
}
#define PREPARE alternative_main
#include <support/test-driver.c>
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