/*
* Copyright (c) 2017 Google, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program, if not, see <http://www.gnu.org/licenses/>.
*/
/*
* Regression test for commit 63a0b0509e70 ("KEYS: fix freeing uninitialized
* memory in key_update()"). Try to reproduce the crash in two different ways:
*
* 1. Try to update a key of a type that has a ->preparse() method but not an
* ->update() method. Examples are the "asymmetric" and "dns_resolver" key
* types. It crashes reliably for the "asymmetric" key type, since the
* "asymmetric" key type's ->free_preparse() method will dereference a
* pointer in the uninitialized memory, whereas other key types often just
* free a pointer which tends be NULL in practice, depending on how the stack
* is laid out. However, to actually be able to add an "asymmetric" key, we
* need a specially-formatted payload and several kernel config options. We
* do try it, but for completeness we also try the "dns_resolver" key type
* (though that's not guaranteed to be available either).
*
* 2. Race keyctl_update() with another task removing write permission from the
* key using keyctl_setperm(). This can cause a crash with almost any key
* type. "user" is a good one to try, since it's always available if
* keyrings are supported at all. However, depending on how the stack is
* laid out the crash may not actually occur.
*/
#include <errno.h>
#include <stdlib.h>
#include "tst_test.h"
#include "lapi/keyctl.h"
#define KEY_POS_WRITE 0x04000000
#define KEY_POS_ALL 0x3f000000
/*
* A valid payload for the "asymmetric" key type. This is an x509 certificate
* in DER format, generated using:
*
* openssl req -x509 -newkey rsa:512 -batch -nodes -outform der \
* | ~/linux/scripts/bin2c
*/
static const char x509_cert[] =
"\x30\x82\x01\xd3\x30\x82\x01\x7d\xa0\x03\x02\x01\x02\x02\x09\x00"
"\x92\x2a\x76\xff\x0c\x00\xfb\x9a\x30\x0d\x06\x09\x2a\x86\x48\x86"
"\xf7\x0d\x01\x01\x0b\x05\x00\x30\x45\x31\x0b\x30\x09\x06\x03\x55"
"\x04\x06\x13\x02\x41\x55\x31\x13\x30\x11\x06\x03\x55\x04\x08\x0c"
"\x0a\x53\x6f\x6d\x65\x2d\x53\x74\x61\x74\x65\x31\x21\x30\x1f\x06"
"\x03\x55\x04\x0a\x0c\x18\x49\x6e\x74\x65\x72\x6e\x65\x74\x20\x57"
"\x69\x64\x67\x69\x74\x73\x20\x50\x74\x79\x20\x4c\x74\x64\x30\x1e"
"\x17\x0d\x31\x37\x30\x37\x32\x38\x32\x31\x34\x31\x33\x34\x5a\x17"
"\x0d\x31\x37\x30\x38\x32\x37\x32\x31\x34\x31\x33\x34\x5a\x30\x45"
"\x31\x0b\x30\x09\x06\x03\x55\x04\x06\x13\x02\x41\x55\x31\x13\x30"
"\x11\x06\x03\x55\x04\x08\x0c\x0a\x53\x6f\x6d\x65\x2d\x53\x74\x61"
"\x74\x65\x31\x21\x30\x1f\x06\x03\x55\x04\x0a\x0c\x18\x49\x6e\x74"
"\x65\x72\x6e\x65\x74\x20\x57\x69\x64\x67\x69\x74\x73\x20\x50\x74"
"\x79\x20\x4c\x74\x64\x30\x5c\x30\x0d\x06\x09\x2a\x86\x48\x86\xf7"
"\x0d\x01\x01\x01\x05\x00\x03\x4b\x00\x30\x48\x02\x41\x00\xde\x0b"
"\x1c\x24\xe2\x0d\xf8\x17\xf2\xc3\x6f\xc9\x72\x3e\x9d\xb0\x2d\x47"
"\xe4\xc4\x85\x87\xed\xde\x06\xe3\xf3\xe9\x4c\x35\x6c\xe4\xcb\x0e"
"\x44\x28\x23\x66\x76\xec\x4e\xdf\x10\x93\x92\x1e\x52\xfb\xdf\x5c"
"\x08\xe7\x24\x04\x66\xe3\x06\x05\x27\x56\xfb\x3e\x91\x31\x02\x03"
"\x01\x00\x01\xa3\x50\x30\x4e\x30\x1d\x06\x03\x55\x1d\x0e\x04\x16"
"\x04\x14\x6f\x39\x3a\x46\xdf\x29\x63\xde\x54\x7b\x6c\x31\x06\xd0"
"\x9f\x36\x16\xfb\x9c\xbf\x30\x1f\x06\x03\x55\x1d\x23\x04\x18\x30"
"\x16\x80\x14\x6f\x39\x3a\x46\xdf\x29\x63\xde\x54\x7b\x6c\x31\x06"
"\xd0\x9f\x36\x16\xfb\x9c\xbf\x30\x0c\x06\x03\x55\x1d\x13\x04\x05"
"\x30\x03\x01\x01\xff\x30\x0d\x06\x09\x2a\x86\x48\x86\xf7\x0d\x01"
"\x01\x0b\x05\x00\x03\x41\x00\x73\xf0\x4b\x62\x56\xed\xf0\x8b\x7e"
"\xc4\x75\x78\x98\xa2\x7a\x6e\x75\x1f\xde\x9b\xa0\xbe\x1a\x1f\x86"
"\x44\x13\xcd\x45\x06\x7f\x86\xde\xf6\x36\x4e\xb6\x15\xfa\xf5\xb0"
"\x34\xd2\x5e\x0b\xb3\x2c\x03\x5a\x5a\x28\x97\x5e\x7b\xdf\x63\x75"
"\x83\x8d\x69\xda\xd6\x59\xbd"
;
static void new_session_keyring(void)
{
TEST(keyctl(KEYCTL_JOIN_SESSION_KEYRING, NULL));
if (TEST_RETURN < 0)
tst_brk(TBROK | TTERRNO, "failed to join new session keyring");
}
static void test_update_nonupdatable(const char *type,
const void *payload, size_t plen)
{
key_serial_t keyid;
new_session_keyring();
TEST(add_key(type, "desc", payload, plen, KEY_SPEC_SESSION_KEYRING));
if (TEST_RETURN < 0) {
if (TEST_ERRNO == ENODEV) {
tst_res(TCONF, "kernel doesn't support key type '%s'",
type);
return;
}
if (TEST_ERRNO == EBADMSG && !strcmp(type, "asymmetric")) {
tst_res(TCONF, "kernel is missing x509 cert parser "
"(CONFIG_X509_CERTIFICATE_PARSER)");
return;
}
if (TEST_ERRNO == ENOENT && !strcmp(type, "asymmetric")) {
tst_res(TCONF, "kernel is missing crypto algorithms "
"needed to parse x509 cert (CONFIG_CRYPTO_RSA "
"and/or CONFIG_CRYPTO_SHA256)");
return;
}
tst_res(TBROK | TTERRNO, "unexpected error adding '%s' key",
type);
return;
}
keyid = TEST_RETURN;
/*
* Non-updatable keys don't start with write permission, so we must
* explicitly grant it.
*/
TEST(keyctl(KEYCTL_SETPERM, keyid, KEY_POS_ALL));
if (TEST_RETURN != 0) {
tst_res(TBROK | TTERRNO,
"failed to grant write permission to '%s' key", type);
return;
}
tst_res(TINFO, "Try to update the '%s' key...", type);
TEST(keyctl(KEYCTL_UPDATE, keyid, payload, plen));
if (TEST_RETURN == 0) {
tst_res(TBROK,
"updating '%s' key unexpectedly succeeded", type);
return;
}
if (TEST_ERRNO != EOPNOTSUPP) {
tst_res(TBROK | TTERRNO,
"updating '%s' key unexpectedly failed", type);
return;
}
tst_res(TPASS, "updating '%s' key expectedly failed with EOPNOTSUPP",
type);
}
/*
* Try to update a key, racing with removing write permission.
* This may crash buggy kernels.
*/
static void test_update_setperm_race(void)
{
static const char payload[] = "payload";
key_serial_t keyid;
int i;
new_session_keyring();
TEST(add_key("user", "desc", payload, sizeof(payload),
KEY_SPEC_SESSION_KEYRING));
if (TEST_RETURN < 0) {
tst_res(TBROK | TTERRNO, "failed to add 'user' key");
return;
}
keyid = TEST_RETURN;
if (SAFE_FORK() == 0) {
uint32_t perm = KEY_POS_ALL;
for (i = 0; i < 10000; i++) {
perm ^= KEY_POS_WRITE;
TEST(keyctl(KEYCTL_SETPERM, keyid, perm));
if (TEST_RETURN != 0)
tst_brk(TBROK | TTERRNO, "setperm failed");
}
exit(0);
}
tst_res(TINFO, "Try to update the 'user' key...");
for (i = 0; i < 10000; i++) {
TEST(keyctl(KEYCTL_UPDATE, keyid, payload, sizeof(payload)));
if (TEST_RETURN != 0 && TEST_ERRNO != EACCES) {
tst_res(TBROK | TTERRNO, "failed to update 'user' key");
return;
}
}
tst_reap_children();
tst_res(TPASS, "didn't crash while racing to update 'user' key");
}
static void do_test(unsigned int i)
{
/* two 0 bytes is accepted as a dns_resolver key payload */
static char zeroes[2];
switch (i) {
case 0:
test_update_nonupdatable("asymmetric",
x509_cert, sizeof(x509_cert));
break;
case 1:
test_update_nonupdatable("dns_resolver",
zeroes, sizeof(zeroes));
break;
case 2:
test_update_setperm_race();
break;
}
}
static struct tst_test test = {
.tcnt = 3,
.test = do_test,
.forks_child = 1,
};