1 /* 2 * Copyright (c) 2017 Google, Inc. 3 * 4 * This program is free software: you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License as published by 6 * the Free Software Foundation, either version 2 of the License, or 7 * (at your option) any later version. 8 * 9 * This program is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 * GNU General Public License for more details. 13 * 14 * You should have received a copy of the GNU General Public License 15 * along with this program, if not, see <http://www.gnu.org/licenses/>. 16 */ 17 18 /* 19 * Regression test for commit 63a0b0509e70 ("KEYS: fix freeing uninitialized 20 * memory in key_update()"). Try to reproduce the crash in two different ways: 21 * 22 * 1. Try to update a key of a type that has a ->preparse() method but not an 23 * ->update() method. Examples are the "asymmetric" and "dns_resolver" key 24 * types. It crashes reliably for the "asymmetric" key type, since the 25 * "asymmetric" key type's ->free_preparse() method will dereference a 26 * pointer in the uninitialized memory, whereas other key types often just 27 * free a pointer which tends be NULL in practice, depending on how the stack 28 * is laid out. However, to actually be able to add an "asymmetric" key, we 29 * need a specially-formatted payload and several kernel config options. We 30 * do try it, but for completeness we also try the "dns_resolver" key type 31 * (though that's not guaranteed to be available either). 32 * 33 * 2. Race keyctl_update() with another task removing write permission from the 34 * key using keyctl_setperm(). This can cause a crash with almost any key 35 * type. "user" is a good one to try, since it's always available if 36 * keyrings are supported at all. However, depending on how the stack is 37 * laid out the crash may not actually occur. 38 */ 39 40 #include <errno.h> 41 #include <stdlib.h> 42 43 #include "tst_test.h" 44 #include "lapi/keyctl.h" 45 46 #define KEY_POS_WRITE 0x04000000 47 #define KEY_POS_ALL 0x3f000000 48 49 /* 50 * A valid payload for the "asymmetric" key type. This is an x509 certificate 51 * in DER format, generated using: 52 * 53 * openssl req -x509 -newkey rsa:512 -batch -nodes -outform der \ 54 * | ~/linux/scripts/bin2c 55 */ 56 static const char x509_cert[] = 57 "\x30\x82\x01\xd3\x30\x82\x01\x7d\xa0\x03\x02\x01\x02\x02\x09\x00" 58 "\x92\x2a\x76\xff\x0c\x00\xfb\x9a\x30\x0d\x06\x09\x2a\x86\x48\x86" 59 "\xf7\x0d\x01\x01\x0b\x05\x00\x30\x45\x31\x0b\x30\x09\x06\x03\x55" 60 "\x04\x06\x13\x02\x41\x55\x31\x13\x30\x11\x06\x03\x55\x04\x08\x0c" 61 "\x0a\x53\x6f\x6d\x65\x2d\x53\x74\x61\x74\x65\x31\x21\x30\x1f\x06" 62 "\x03\x55\x04\x0a\x0c\x18\x49\x6e\x74\x65\x72\x6e\x65\x74\x20\x57" 63 "\x69\x64\x67\x69\x74\x73\x20\x50\x74\x79\x20\x4c\x74\x64\x30\x1e" 64 "\x17\x0d\x31\x37\x30\x37\x32\x38\x32\x31\x34\x31\x33\x34\x5a\x17" 65 "\x0d\x31\x37\x30\x38\x32\x37\x32\x31\x34\x31\x33\x34\x5a\x30\x45" 66 "\x31\x0b\x30\x09\x06\x03\x55\x04\x06\x13\x02\x41\x55\x31\x13\x30" 67 "\x11\x06\x03\x55\x04\x08\x0c\x0a\x53\x6f\x6d\x65\x2d\x53\x74\x61" 68 "\x74\x65\x31\x21\x30\x1f\x06\x03\x55\x04\x0a\x0c\x18\x49\x6e\x74" 69 "\x65\x72\x6e\x65\x74\x20\x57\x69\x64\x67\x69\x74\x73\x20\x50\x74" 70 "\x79\x20\x4c\x74\x64\x30\x5c\x30\x0d\x06\x09\x2a\x86\x48\x86\xf7" 71 "\x0d\x01\x01\x01\x05\x00\x03\x4b\x00\x30\x48\x02\x41\x00\xde\x0b" 72 "\x1c\x24\xe2\x0d\xf8\x17\xf2\xc3\x6f\xc9\x72\x3e\x9d\xb0\x2d\x47" 73 "\xe4\xc4\x85\x87\xed\xde\x06\xe3\xf3\xe9\x4c\x35\x6c\xe4\xcb\x0e" 74 "\x44\x28\x23\x66\x76\xec\x4e\xdf\x10\x93\x92\x1e\x52\xfb\xdf\x5c" 75 "\x08\xe7\x24\x04\x66\xe3\x06\x05\x27\x56\xfb\x3e\x91\x31\x02\x03" 76 "\x01\x00\x01\xa3\x50\x30\x4e\x30\x1d\x06\x03\x55\x1d\x0e\x04\x16" 77 "\x04\x14\x6f\x39\x3a\x46\xdf\x29\x63\xde\x54\x7b\x6c\x31\x06\xd0" 78 "\x9f\x36\x16\xfb\x9c\xbf\x30\x1f\x06\x03\x55\x1d\x23\x04\x18\x30" 79 "\x16\x80\x14\x6f\x39\x3a\x46\xdf\x29\x63\xde\x54\x7b\x6c\x31\x06" 80 "\xd0\x9f\x36\x16\xfb\x9c\xbf\x30\x0c\x06\x03\x55\x1d\x13\x04\x05" 81 "\x30\x03\x01\x01\xff\x30\x0d\x06\x09\x2a\x86\x48\x86\xf7\x0d\x01" 82 "\x01\x0b\x05\x00\x03\x41\x00\x73\xf0\x4b\x62\x56\xed\xf0\x8b\x7e" 83 "\xc4\x75\x78\x98\xa2\x7a\x6e\x75\x1f\xde\x9b\xa0\xbe\x1a\x1f\x86" 84 "\x44\x13\xcd\x45\x06\x7f\x86\xde\xf6\x36\x4e\xb6\x15\xfa\xf5\xb0" 85 "\x34\xd2\x5e\x0b\xb3\x2c\x03\x5a\x5a\x28\x97\x5e\x7b\xdf\x63\x75" 86 "\x83\x8d\x69\xda\xd6\x59\xbd" 87 ; 88 89 static void new_session_keyring(void) 90 { 91 TEST(keyctl(KEYCTL_JOIN_SESSION_KEYRING, NULL)); 92 if (TEST_RETURN < 0) 93 tst_brk(TBROK | TTERRNO, "failed to join new session keyring"); 94 } 95 96 static void test_update_nonupdatable(const char *type, 97 const void *payload, size_t plen) 98 { 99 key_serial_t keyid; 100 101 new_session_keyring(); 102 103 TEST(add_key(type, "desc", payload, plen, KEY_SPEC_SESSION_KEYRING)); 104 if (TEST_RETURN < 0) { 105 if (TEST_ERRNO == ENODEV) { 106 tst_res(TCONF, "kernel doesn't support key type '%s'", 107 type); 108 return; 109 } 110 if (TEST_ERRNO == EBADMSG && !strcmp(type, "asymmetric")) { 111 tst_res(TCONF, "kernel is missing x509 cert parser " 112 "(CONFIG_X509_CERTIFICATE_PARSER)"); 113 return; 114 } 115 if (TEST_ERRNO == ENOENT && !strcmp(type, "asymmetric")) { 116 tst_res(TCONF, "kernel is missing crypto algorithms " 117 "needed to parse x509 cert (CONFIG_CRYPTO_RSA " 118 "and/or CONFIG_CRYPTO_SHA256)"); 119 return; 120 } 121 tst_res(TBROK | TTERRNO, "unexpected error adding '%s' key", 122 type); 123 return; 124 } 125 keyid = TEST_RETURN; 126 127 /* 128 * Non-updatable keys don't start with write permission, so we must 129 * explicitly grant it. 130 */ 131 TEST(keyctl(KEYCTL_SETPERM, keyid, KEY_POS_ALL)); 132 if (TEST_RETURN != 0) { 133 tst_res(TBROK | TTERRNO, 134 "failed to grant write permission to '%s' key", type); 135 return; 136 } 137 138 tst_res(TINFO, "Try to update the '%s' key...", type); 139 TEST(keyctl(KEYCTL_UPDATE, keyid, payload, plen)); 140 if (TEST_RETURN == 0) { 141 tst_res(TBROK, 142 "updating '%s' key unexpectedly succeeded", type); 143 return; 144 } 145 if (TEST_ERRNO != EOPNOTSUPP) { 146 tst_res(TBROK | TTERRNO, 147 "updating '%s' key unexpectedly failed", type); 148 return; 149 } 150 tst_res(TPASS, "updating '%s' key expectedly failed with EOPNOTSUPP", 151 type); 152 } 153 154 /* 155 * Try to update a key, racing with removing write permission. 156 * This may crash buggy kernels. 157 */ 158 static void test_update_setperm_race(void) 159 { 160 static const char payload[] = "payload"; 161 key_serial_t keyid; 162 int i; 163 164 new_session_keyring(); 165 166 TEST(add_key("user", "desc", payload, sizeof(payload), 167 KEY_SPEC_SESSION_KEYRING)); 168 if (TEST_RETURN < 0) { 169 tst_res(TBROK | TTERRNO, "failed to add 'user' key"); 170 return; 171 } 172 keyid = TEST_RETURN; 173 174 if (SAFE_FORK() == 0) { 175 uint32_t perm = KEY_POS_ALL; 176 177 for (i = 0; i < 10000; i++) { 178 perm ^= KEY_POS_WRITE; 179 TEST(keyctl(KEYCTL_SETPERM, keyid, perm)); 180 if (TEST_RETURN != 0) 181 tst_brk(TBROK | TTERRNO, "setperm failed"); 182 } 183 exit(0); 184 } 185 186 tst_res(TINFO, "Try to update the 'user' key..."); 187 for (i = 0; i < 10000; i++) { 188 TEST(keyctl(KEYCTL_UPDATE, keyid, payload, sizeof(payload))); 189 if (TEST_RETURN != 0 && TEST_ERRNO != EACCES) { 190 tst_res(TBROK | TTERRNO, "failed to update 'user' key"); 191 return; 192 } 193 } 194 tst_reap_children(); 195 tst_res(TPASS, "didn't crash while racing to update 'user' key"); 196 } 197 198 static void do_test(unsigned int i) 199 { 200 /* two 0 bytes is accepted as a dns_resolver key payload */ 201 static char zeroes[2]; 202 203 switch (i) { 204 case 0: 205 test_update_nonupdatable("asymmetric", 206 x509_cert, sizeof(x509_cert)); 207 break; 208 case 1: 209 test_update_nonupdatable("dns_resolver", 210 zeroes, sizeof(zeroes)); 211 break; 212 case 2: 213 test_update_setperm_race(); 214 break; 215 } 216 } 217 218 static struct tst_test test = { 219 .tcnt = 3, 220 .test = do_test, 221 .forks_child = 1, 222 }; 223
