146 lines
3.5 KiB
C
146 lines
3.5 KiB
C
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// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Copyright (c) International Business Machines Corp., 2002
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* Ported from SPIE by Airong Zhang <zhanga@us.ibm.com>
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* Copyright (c) 2021 SUSE LLC <mdoucha@suse.cz>
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*/
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/*\
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* [Description]
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*
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* Verify that the group ID and setgid bit are set correctly when a new file
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* is created.
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*/
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#include <stdlib.h>
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#include <sys/types.h>
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#include <pwd.h>
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#include "tst_test.h"
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#include "tst_uid.h"
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#define MODE_RWX 0777
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#define MODE_SGID (S_ISGID|0777)
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#define DIR_A "dir_a"
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#define DIR_B "dir_b"
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#define SETGID_A DIR_A "/setgid"
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#define NOSETGID_A DIR_A "/nosetgid"
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#define SETGID_B DIR_B "/setgid"
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#define NOSETGID_B DIR_B "/nosetgid"
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#define ROOT_SETGID DIR_B "/root_setgid"
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static char *tmpdir;
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static uid_t orig_uid, nobody_uid;
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static gid_t nobody_gid, free_gid;
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static int fd = -1;
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static void setup(void)
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{
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struct passwd *ltpuser = SAFE_GETPWNAM("nobody");
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orig_uid = getuid();
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nobody_uid = ltpuser->pw_uid;
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nobody_gid = ltpuser->pw_gid;
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tst_res(TINFO, "User nobody: uid = %d, gid = %d", (int)nobody_uid,
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(int)nobody_gid);
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free_gid = tst_get_free_gid(nobody_gid);
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tmpdir = tst_get_tmpdir();
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}
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static void file_test(const char *name, mode_t mode, int sgid, gid_t gid)
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{
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struct stat buf;
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fd = SAFE_CREAT(name, mode);
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SAFE_STAT(name, &buf);
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SAFE_CLOSE(fd);
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if (buf.st_gid != gid) {
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tst_res(TFAIL, "%s: Incorrect group, %u != %u", name,
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buf.st_gid, gid);
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} else {
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tst_res(TPASS, "%s: Owned by correct group", name);
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}
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if (sgid < 0) {
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tst_res(TINFO, "%s: Skipping setgid bit check", name);
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return;
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}
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if (buf.st_mode & S_ISGID)
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tst_res(sgid ? TPASS : TFAIL, "%s: Setgid bit is set", name);
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else
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tst_res(sgid ? TFAIL : TPASS, "%s: Setgid bit not set", name);
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}
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static void run(void)
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{
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struct stat buf;
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/* Create directories and set permissions */
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SAFE_MKDIR(DIR_A, MODE_RWX);
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SAFE_CHOWN(DIR_A, nobody_uid, free_gid);
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SAFE_STAT(DIR_A, &buf);
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if (buf.st_mode & S_ISGID)
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tst_brk(TBROK, "%s: Setgid bit is set", DIR_A);
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if (buf.st_gid != free_gid) {
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tst_brk(TBROK, "%s: Incorrect group, %u != %u", DIR_A,
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buf.st_gid, free_gid);
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}
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SAFE_MKDIR(DIR_B, MODE_RWX);
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SAFE_CHOWN(DIR_B, nobody_uid, free_gid);
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SAFE_CHMOD(DIR_B, MODE_SGID);
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SAFE_STAT(DIR_B, &buf);
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if (!(buf.st_mode & S_ISGID))
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tst_brk(TBROK, "%s: Setgid bit not set", DIR_B);
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if (buf.st_gid != free_gid) {
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tst_brk(TBROK, "%s: Incorrect group, %u != %u", DIR_B,
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buf.st_gid, free_gid);
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}
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/* Switch to user nobody and create two files in DIR_A */
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/* Both files should inherit GID from the process */
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SAFE_SETGID(nobody_gid);
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SAFE_SETREUID(-1, nobody_uid);
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file_test(NOSETGID_A, MODE_RWX, 0, nobody_gid);
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file_test(SETGID_A, MODE_SGID, 1, nobody_gid);
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/* Create two files in DIR_B and validate owner and permissions */
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/* Both files should inherit GID from the parent directory */
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file_test(NOSETGID_B, MODE_RWX, 0, free_gid);
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/*
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* CVE 2018-13405 (privilege escalation using setgid bit) has its
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* own test, skip setgid check here
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*/
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file_test(SETGID_B, MODE_SGID, -1, free_gid);
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/* Switch back to root UID and create a file in DIR_B */
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/* The file should inherid GID from parent directory */
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SAFE_SETREUID(-1, orig_uid);
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file_test(ROOT_SETGID, MODE_SGID, 1, free_gid);
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/* Cleanup between loops */
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tst_purge_dir(tmpdir);
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}
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static void cleanup(void)
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{
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if (fd >= 0)
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SAFE_CLOSE(fd);
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free(tmpdir);
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}
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static struct tst_test test = {
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.test_all = run,
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.setup = setup,
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.cleanup = cleanup,
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.needs_root = 1,
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.needs_tmpdir = 1,
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};
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