1/*
2 * Copyright (c) 2017 Fujitsu Ltd.
3 *  Ported: Guangwen Feng <fenggw-fnst@cn.fujitsu.com>
4 *
5 * This program is free software: you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation, either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program, if not, see <http://www.gnu.org/licenses/>.
17 */
18
19/*
20 * This is a regression test for the race between keyctl_read() and
21 * keyctl_revoke(), if the revoke happens between keyctl_read()
22 * checking the validity of a key and the key's semaphore being taken,
23 * then the key type read method will see a revoked key.
24 *
25 * This causes a problem for the user-defined key type because it
26 * assumes in its read method that there will always be a payload
27 * in a non-revoked key and doesn't check for a NULL pointer.
28 *
29 * This test can crash the buggy kernel, and the bug was fixed in:
30 *
31 *  commit b4a1b4f5047e4f54e194681125c74c0aa64d637d
32 *  Author: David Howells <dhowells@redhat.com>
33 *  Date:   Fri Dec 18 01:34:26 2015 +0000
34 *
35 *  KEYS: Fix race between read and revoke
36 */
37
38#include <errno.h>
39#include <pthread.h>
40#include <sys/types.h>
41
42#include "tst_safe_pthread.h"
43#include "tst_test.h"
44#include "lapi/keyctl.h"
45
46#define LOOPS	20000
47#define PATH_KEY_COUNT_QUOTA	"/proc/sys/kernel/keys/root_maxkeys"
48
49static int orig_maxkeys;
50
51static void *do_read(void *arg)
52{
53	key_serial_t key = (unsigned long)arg;
54	char buffer[4] = { 0 };
55
56	keyctl(KEYCTL_READ, key, buffer, 4);
57
58	return NULL;
59}
60
61static void *do_revoke(void *arg)
62{
63	key_serial_t key = (unsigned long)arg;
64
65	keyctl(KEYCTL_REVOKE, key);
66
67	return NULL;
68}
69
70static void do_test(void)
71{
72	int i;
73	key_serial_t key;
74	pthread_t pth[4];
75
76	for (i = 0; i < LOOPS; i++) {
77		key = add_key("user", "ltptestkey", "foo", 3,
78			KEY_SPEC_PROCESS_KEYRING);
79		if (key == -1)
80			tst_brk(TBROK | TERRNO, "Failed to add key");
81
82		SAFE_PTHREAD_CREATE(&pth[0], NULL, do_read,
83			(void *)(unsigned long)key);
84		SAFE_PTHREAD_CREATE(&pth[1], NULL, do_revoke,
85			(void *)(unsigned long)key);
86		SAFE_PTHREAD_CREATE(&pth[2], NULL, do_read,
87			(void *)(unsigned long)key);
88		SAFE_PTHREAD_CREATE(&pth[3], NULL, do_revoke,
89			(void *)(unsigned long)key);
90
91		SAFE_PTHREAD_JOIN(pth[0], NULL);
92		SAFE_PTHREAD_JOIN(pth[1], NULL);
93		SAFE_PTHREAD_JOIN(pth[2], NULL);
94		SAFE_PTHREAD_JOIN(pth[3], NULL);
95	}
96
97	tst_res(TPASS, "Bug not reproduced");
98}
99
100static void setup(void)
101{
102	SAFE_FILE_SCANF(PATH_KEY_COUNT_QUOTA, "%d", &orig_maxkeys);
103	SAFE_FILE_PRINTF(PATH_KEY_COUNT_QUOTA, "%d", orig_maxkeys + LOOPS);
104}
105
106static void cleanup(void)
107{
108	if (orig_maxkeys > 0)
109		SAFE_FILE_PRINTF(PATH_KEY_COUNT_QUOTA, "%d", orig_maxkeys);
110}
111
112static struct tst_test test = {
113	.needs_root = 1,
114	.setup = setup,
115	.cleanup = cleanup,
116	.test_all = do_test,
117};
118