diff options
Diffstat (limited to 'elf/tst-env-setuid.c')
| -rw-r--r-- | elf/tst-env-setuid.c | 282 |
1 files changed, 282 insertions, 0 deletions
diff --git a/elf/tst-env-setuid.c b/elf/tst-env-setuid.c new file mode 100644 index 0000000000..85d423d799 --- /dev/null +++ b/elf/tst-env-setuid.c @@ -0,0 +1,282 @@ +/* Copyright (C) 2012-2017 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 + <http://www.gnu.org/licenses/>. */ + +/* Verify that tunables correctly filter out unsafe environment variables like + MALLOC_CHECK_ and MALLOC_MMAP_THRESHOLD_ but also retain + MALLOC_MMAP_THRESHOLD_ in an unprivileged child. */ + +#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 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 (!WIFEXITED (status) || WEXITSTATUS (status) != CHILD_STATUS) + { + printf ("Unexpected exit status %d from child process\n", + 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 +test_child (void) +{ + if (getenv ("MALLOC_CHECK_") != NULL) + { + printf ("MALLOC_CHECK_ is still set\n"); + return 1; + } + + if (getenv ("MALLOC_MMAP_THRESHOLD_") == NULL) + { + printf ("MALLOC_MMAP_THRESHOLD_ lost\n"); + return 1; + } + + return 0; +} +#endif + +#ifndef test_parent +static int +test_parent (void) +{ + if (getenv ("MALLOC_CHECK_") == NULL) + { + printf ("MALLOC_CHECK_ lost\n"); + return 1; + } + + if (getenv ("MALLOC_MMAP_THRESHOLD_") == NULL) + { + printf ("MALLOC_MMAP_THRESHOLD_ lost\n"); + return 1; + } + + return 0; +} +#endif + +static int +do_test_prep (int argc, char **argv) +{ + /* Setgid child process. */ + 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", + (intmax_t) getgid ()); + exit (EXIT_UNSUPPORTED); + } + + int ret = test_child (); + + if (ret != 0) + exit (1); + + exit (CHILD_STATUS); + } + 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); + } + + if (run_executable_sgid (target) == 0) + exit (0); + } + + /* Something went wrong and our argv was corrupted. */ + _exit (1); +} + +#define TEST_FUNCTION_ARGV do_test_prep +#include <support/test-driver.c> |