1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (c) 2017 Google, Inc.
4 */
5
6 /*
7 * Regression test for commit 63a0b0509e70 ("KEYS: fix freeing uninitialized
8 * memory in key_update()"). Try to reproduce the crash in two different ways:
9 *
10 * 1. Try to update a key of a type that has a ->preparse() method but not an
11 * ->update() method. Examples are the "asymmetric" and "dns_resolver" key
12 * types. It crashes reliably for the "asymmetric" key type, since the
13 * "asymmetric" key type's ->free_preparse() method will dereference a
14 * pointer in the uninitialized memory, whereas other key types often just
15 * free a pointer which tends be NULL in practice, depending on how the stack
16 * is laid out. However, to actually be able to add an "asymmetric" key, we
17 * need a specially-formatted payload and several kernel config options. We
18 * do try it, but for completeness we also try the "dns_resolver" key type
19 * (though that's not guaranteed to be available either).
20 *
21 * 2. Race keyctl_update() with another task removing write permission from the
22 * key using keyctl_setperm(). This can cause a crash with almost any key
23 * type. "user" is a good one to try, since it's always available if
24 * keyrings are supported at all. However, depending on how the stack is
25 * laid out the crash may not actually occur.
26 */
27
28 #include <errno.h>
29 #include <stdlib.h>
30
31 #include "tst_test.h"
32 #include "lapi/keyctl.h"
33
34 /*
35 * A valid payload for the "asymmetric" key type. This is an x509 certificate
36 * in DER format, generated using:
37 *
38 * openssl req -x509 -newkey rsa:512 -batch -nodes -outform der \
39 * | ~/linux/scripts/bin2c
40 */
41 static const char x509_cert[] =
42 "\x30\x82\x01\xd3\x30\x82\x01\x7d\xa0\x03\x02\x01\x02\x02\x09\x00"
43 "\x92\x2a\x76\xff\x0c\x00\xfb\x9a\x30\x0d\x06\x09\x2a\x86\x48\x86"
44 "\xf7\x0d\x01\x01\x0b\x05\x00\x30\x45\x31\x0b\x30\x09\x06\x03\x55"
45 "\x04\x06\x13\x02\x41\x55\x31\x13\x30\x11\x06\x03\x55\x04\x08\x0c"
46 "\x0a\x53\x6f\x6d\x65\x2d\x53\x74\x61\x74\x65\x31\x21\x30\x1f\x06"
47 "\x03\x55\x04\x0a\x0c\x18\x49\x6e\x74\x65\x72\x6e\x65\x74\x20\x57"
48 "\x69\x64\x67\x69\x74\x73\x20\x50\x74\x79\x20\x4c\x74\x64\x30\x1e"
49 "\x17\x0d\x31\x37\x30\x37\x32\x38\x32\x31\x34\x31\x33\x34\x5a\x17"
50 "\x0d\x31\x37\x30\x38\x32\x37\x32\x31\x34\x31\x33\x34\x5a\x30\x45"
51 "\x31\x0b\x30\x09\x06\x03\x55\x04\x06\x13\x02\x41\x55\x31\x13\x30"
52 "\x11\x06\x03\x55\x04\x08\x0c\x0a\x53\x6f\x6d\x65\x2d\x53\x74\x61"
53 "\x74\x65\x31\x21\x30\x1f\x06\x03\x55\x04\x0a\x0c\x18\x49\x6e\x74"
54 "\x65\x72\x6e\x65\x74\x20\x57\x69\x64\x67\x69\x74\x73\x20\x50\x74"
55 "\x79\x20\x4c\x74\x64\x30\x5c\x30\x0d\x06\x09\x2a\x86\x48\x86\xf7"
56 "\x0d\x01\x01\x01\x05\x00\x03\x4b\x00\x30\x48\x02\x41\x00\xde\x0b"
57 "\x1c\x24\xe2\x0d\xf8\x17\xf2\xc3\x6f\xc9\x72\x3e\x9d\xb0\x2d\x47"
58 "\xe4\xc4\x85\x87\xed\xde\x06\xe3\xf3\xe9\x4c\x35\x6c\xe4\xcb\x0e"
59 "\x44\x28\x23\x66\x76\xec\x4e\xdf\x10\x93\x92\x1e\x52\xfb\xdf\x5c"
60 "\x08\xe7\x24\x04\x66\xe3\x06\x05\x27\x56\xfb\x3e\x91\x31\x02\x03"
61 "\x01\x00\x01\xa3\x50\x30\x4e\x30\x1d\x06\x03\x55\x1d\x0e\x04\x16"
62 "\x04\x14\x6f\x39\x3a\x46\xdf\x29\x63\xde\x54\x7b\x6c\x31\x06\xd0"
63 "\x9f\x36\x16\xfb\x9c\xbf\x30\x1f\x06\x03\x55\x1d\x23\x04\x18\x30"
64 "\x16\x80\x14\x6f\x39\x3a\x46\xdf\x29\x63\xde\x54\x7b\x6c\x31\x06"
65 "\xd0\x9f\x36\x16\xfb\x9c\xbf\x30\x0c\x06\x03\x55\x1d\x13\x04\x05"
66 "\x30\x03\x01\x01\xff\x30\x0d\x06\x09\x2a\x86\x48\x86\xf7\x0d\x01"
67 "\x01\x0b\x05\x00\x03\x41\x00\x73\xf0\x4b\x62\x56\xed\xf0\x8b\x7e"
68 "\xc4\x75\x78\x98\xa2\x7a\x6e\x75\x1f\xde\x9b\xa0\xbe\x1a\x1f\x86"
69 "\x44\x13\xcd\x45\x06\x7f\x86\xde\xf6\x36\x4e\xb6\x15\xfa\xf5\xb0"
70 "\x34\xd2\x5e\x0b\xb3\x2c\x03\x5a\x5a\x28\x97\x5e\x7b\xdf\x63\x75"
71 "\x83\x8d\x69\xda\xd6\x59\xbd"
72 ;
73
74 static int fips_enabled;
75
new_session_keyring(void)76 static void new_session_keyring(void)
77 {
78 TEST(keyctl(KEYCTL_JOIN_SESSION_KEYRING, NULL));
79 if (TST_RET < 0)
80 tst_brk(TBROK | TTERRNO, "failed to join new session keyring");
81 }
82
test_update_nonupdatable(const char * type,const void * payload,size_t plen)83 static void test_update_nonupdatable(const char *type,
84 const void *payload, size_t plen)
85 {
86 key_serial_t keyid;
87
88 new_session_keyring();
89
90 int is_asymmetric = !strcmp(type, "asymmetric");
91
92 TEST(add_key(type, "desc", payload, plen, KEY_SPEC_SESSION_KEYRING));
93 if (TST_RET < 0) {
94 if (TST_ERR == EINVAL && is_asymmetric && fips_enabled) {
95 tst_res(TCONF, "key size not allowed in FIPS mode");
96 return;
97 }
98 if (TST_ERR == ENODEV) {
99 tst_res(TCONF, "kernel doesn't support key type '%s'",
100 type);
101 return;
102 }
103 if (TST_ERR == EBADMSG && is_asymmetric) {
104 tst_res(TCONF, "kernel is missing x509 cert parser "
105 "(CONFIG_X509_CERTIFICATE_PARSER)");
106 return;
107 }
108 if (TST_ERR == ENOENT && is_asymmetric) {
109 tst_res(TCONF, "kernel is missing crypto algorithms "
110 "needed to parse x509 cert (CONFIG_CRYPTO_RSA "
111 "and/or CONFIG_CRYPTO_SHA256)");
112 return;
113 }
114 tst_res(TFAIL | TTERRNO, "unexpected error adding '%s' key",
115 type);
116 return;
117 }
118 keyid = TST_RET;
119
120 /*
121 * Non-updatable keys don't start with write permission, so we must
122 * explicitly grant it.
123 */
124 TEST(keyctl(KEYCTL_SETPERM, keyid, KEY_POS_ALL));
125 if (TST_RET != 0) {
126 tst_res(TFAIL | TTERRNO,
127 "failed to grant write permission to '%s' key", type);
128 return;
129 }
130
131 tst_res(TINFO, "Try to update the '%s' key...", type);
132 TEST(keyctl(KEYCTL_UPDATE, keyid, payload, plen));
133 if (TST_RET == 0) {
134 tst_res(TFAIL,
135 "updating '%s' key unexpectedly succeeded", type);
136 return;
137 }
138 if (TST_ERR != EOPNOTSUPP) {
139 tst_res(TFAIL | TTERRNO,
140 "updating '%s' key unexpectedly failed", type);
141 return;
142 }
143 tst_res(TPASS, "updating '%s' key expectedly failed with EOPNOTSUPP",
144 type);
145 }
146
147 /*
148 * Try to update a key, racing with removing write permission.
149 * This may crash buggy kernels.
150 */
test_update_setperm_race(void)151 static void test_update_setperm_race(void)
152 {
153 static const char payload[] = "payload";
154 key_serial_t keyid;
155 int i;
156
157 new_session_keyring();
158
159 TEST(add_key("user", "desc", payload, sizeof(payload),
160 KEY_SPEC_SESSION_KEYRING));
161 if (TST_RET < 0) {
162 tst_res(TFAIL | TTERRNO, "failed to add 'user' key");
163 return;
164 }
165 keyid = TST_RET;
166
167 if (SAFE_FORK() == 0) {
168 uint32_t perm = KEY_POS_ALL;
169
170 for (i = 0; i < 10000; i++) {
171 perm ^= KEY_POS_WRITE;
172 TEST(keyctl(KEYCTL_SETPERM, keyid, perm));
173 if (TST_RET != 0)
174 tst_brk(TBROK | TTERRNO, "setperm failed");
175 }
176 exit(0);
177 }
178
179 tst_res(TINFO, "Try to update the 'user' key...");
180 for (i = 0; i < 10000; i++) {
181 TEST(keyctl(KEYCTL_UPDATE, keyid, payload, sizeof(payload)));
182 if (TST_RET != 0 && TST_ERR != EACCES) {
183 tst_res(TFAIL | TTERRNO, "failed to update 'user' key");
184 return;
185 }
186 }
187 tst_reap_children();
188 tst_res(TPASS, "didn't crash while racing to update 'user' key");
189 }
190
setup(void)191 static void setup(void)
192 {
193 fips_enabled = tst_fips_enabled();
194 }
195
do_test(unsigned int i)196 static void do_test(unsigned int i)
197 {
198 /*
199 * We need to pass check in dns_resolver_preparse(),
200 * give it dummy server list request.
201 */
202 static char dns_res_payload[] = { 0x00, 0x00, 0x01, 0xff, 0x00 };
203
204 switch (i) {
205 case 0:
206 test_update_nonupdatable("asymmetric",
207 x509_cert, sizeof(x509_cert));
208 break;
209 case 1:
210 test_update_nonupdatable("dns_resolver", dns_res_payload,
211 sizeof(dns_res_payload));
212 break;
213 case 2:
214 test_update_setperm_race();
215 break;
216 }
217 }
218
219 static struct tst_test test = {
220 .tcnt = 3,
221 .setup = setup,
222 .test = do_test,
223 .forks_child = 1,
224 .tags = (const struct tst_tag[]) {
225 {"linux-git", "63a0b0509e70"},
226 {}
227 }
228 };
229