diff options
Diffstat (limited to 'support/support_capture_subprocess.c')
| -rw-r--r-- | support/support_capture_subprocess.c | 126 |
1 files changed, 126 insertions, 0 deletions
diff --git a/support/support_capture_subprocess.c b/support/support_capture_subprocess.c index 7b3d96c305..c64dcf5caf 100644 --- a/support/support_capture_subprocess.c +++ b/support/support_capture_subprocess.c @@ -20,11 +20,14 @@ #include <support/capture_subprocess.h> #include <errno.h> +#include <fcntl.h> #include <stdlib.h> #include <support/check.h> #include <support/xunistd.h> #include <support/xsocket.h> #include <support/xspawn.h> +#include <support/support.h> +#include <support/test-driver.h> static void transfer (const char *what, struct pollfd *pfd, struct xmemstream *stream) @@ -102,6 +105,129 @@ support_capture_subprogram (const char *file, char *const argv[]) return result; } +/* 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 +copy_and_spawn_sgid (char *child_id, gid_t gid) +{ + 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 = 1, status = 1; + + TEST_VERIFY (mkdir (dirname, 0700) == 0); + if (support_record_failure_is_failed ()) + goto err; + + infd = open ("/proc/self/exe", O_RDONLY); + if (infd < 0) + FAIL_UNSUPPORTED ("unsupported: Cannot read binary from procfs\n"); + + outfd = open (execname, O_WRONLY | O_CREAT | O_EXCL, 0700); + TEST_VERIFY (outfd >= 0); + if (support_record_failure_is_failed ()) + goto err; + + char buf[4096]; + for (;;) + { + ssize_t rdcount = read (infd, buf, sizeof (buf)); + TEST_VERIFY (rdcount >= 0); + if (support_record_failure_is_failed ()) + 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; + TEST_VERIFY (wrcount > 0); + if (support_record_failure_is_failed ()) + goto err; + p += wrcount; + } + } + TEST_VERIFY (fchown (outfd, getuid (), gid) == 0); + if (support_record_failure_is_failed ()) + goto err; + TEST_VERIFY (fchmod (outfd, 02750) == 0); + if (support_record_failure_is_failed ()) + goto err; + TEST_VERIFY (close (outfd) == 0); + if (support_record_failure_is_failed ()) + goto err; + TEST_VERIFY (close (infd) == 0); + if (support_record_failure_is_failed ()) + goto err; + + /* We have the binary, now spawn the subprocess. Avoid using + support_subprogram because we only want the program exit status, not the + contents. */ + ret = 0; + + char * const args[] = {execname, child_id, NULL}; + + status = support_subprogram_wait (args[0], args); + +err: + if (outfd >= 0) + close (outfd); + if (infd >= 0) + close (infd); + if (execname != NULL) + { + unlink (execname); + free (execname); + } + if (dirname != NULL) + { + rmdir (dirname); + free (dirname); + } + + if (ret != 0) + FAIL_EXIT1("Failed to make sgid executable for test\n"); + + return status; +} + +int +support_capture_subprogram_self_sgid (char *child_id) +{ + gid_t target = 0; + const int count = 64; + gid_t groups[count]; + + /* Get a GID which is not our current GID, but is present in the + supplementary group list. */ + int ret = getgroups (count, groups); + if (ret < 0) + FAIL_UNSUPPORTED("Could not get group list for user %jd\n", + (intmax_t) getuid ()); + + gid_t current = getgid (); + for (int i = 0; i < ret; ++i) + { + if (groups[i] != current) + { + target = groups[i]; + break; + } + } + + if (target == 0) + FAIL_UNSUPPORTED("Could not find a suitable GID for user %jd\n", + (intmax_t) getuid ()); + + return copy_and_spawn_sgid (child_id, target); +} + void support_capture_subprocess_free (struct support_capture_subprocess *p) { |