/*
* 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 two related bugs:
*
* (1) CVE-2017-15299, fixed by commit 60ff5b2f547a ("KEYS: don't let add_key()
* update an uninstantiated key")
* (2) CVE-2017-15951, fixed by commit 363b02dab09b ("KEYS: Fix race between
* updating and finding a negative key")
*
* We test for the bugs together because the reproduction steps are essentially
* the same: repeatedly try to add/update a key with add_key() while requesting
* it with request_key() in another task. This reproduces both bugs:
*
* For CVE-2017-15299, add_key() has to run while the key being created by
* request_key() is still in the "uninstantiated" state. For the "encrypted" or
* "trusted" key types (not guaranteed to be available) this caused a NULL
* pointer dereference in encrypted_update() or in trusted_update(),
* respectively. For the "user" key type, this caused the WARN_ON() in
* construct_key() to be hit.
*
* For CVE-2017-15951, request_key() has to run while the key is "negatively
* instantiated" (from a prior request_key()) and is being concurrently changed
* to "positively instantiated" via add_key() updating it. This race, which is
* a bit more difficult to reproduce, caused the task executing request_key() to
* dereference an invalid pointer in __key_link_begin().
*/
#include <errno.h>
#include <stdbool.h>
#include <stdlib.h>
#include <sys/wait.h>
#include "tst_test.h"
#include "lapi/keyctl.h"
static char *opt_bug;
static struct tst_option options[] = {
{"b:", &opt_bug, "-b Bug to test for (cve-2017-15299 or cve-2017-15951; default is both)"},
{NULL, NULL, NULL}
};
static void test_with_key_type(const char *type, const char *payload,
int effort)
{
int i;
int status;
pid_t add_key_pid;
pid_t request_key_pid;
bool info_only;
TEST(keyctl(KEYCTL_JOIN_SESSION_KEYRING, NULL));
if (TEST_RETURN < 0)
tst_brk(TBROK | TTERRNO, "failed to join new session keyring");
TEST(add_key(type, "desc", payload, strlen(payload),
KEY_SPEC_SESSION_KEYRING));
if (TEST_RETURN < 0 && TEST_ERRNO != EINVAL) {
if (TEST_ERRNO == ENODEV) {
tst_res(TCONF, "kernel doesn't support key type '%s'",
type);
return;
}
tst_brk(TBROK | TTERRNO,
"unexpected error checking whether key type '%s' is supported",
type);
}
/*
* Fork a subprocess which repeatedly tries to "add" a key of the given
* type. This actually will try to update the key if it already exists.
* Depending on the state of the key, add_key() should either succeed or
* fail with one of several errors:
*
* (1) key didn't exist at all: either add_key() should succeed (if the
* payload is valid), or it should fail with EINVAL (if the payload
* is invalid; this is needed for the "encrypted" and "trusted" key
* types because they have a quirk where the payload syntax differs
* for creating new keys vs. updating existing keys)
*
* (2) key was negative: add_key() should succeed
*
* (3) key was uninstantiated: add_key() should wait for the key to be
* negated, then fail with ENOKEY
*
* For now we also accept EDQUOT because the kernel frees up the keys
* quota asynchronously after keys are unlinked. So it may be hit.
*/
add_key_pid = SAFE_FORK();
if (add_key_pid == 0) {
for (i = 0; i < 100 * effort; i++) {
usleep(rand() % 1024);
TEST(add_key(type, "desc", payload, strlen(payload),
KEY_SPEC_SESSION_KEYRING));
if (TEST_RETURN < 0 && TEST_ERRNO != EINVAL &&
TEST_ERRNO != ENOKEY && TEST_ERRNO != EDQUOT) {
tst_brk(TBROK | TTERRNO,
"unexpected error adding key of type '%s'",
type);
}
TEST(keyctl(KEYCTL_CLEAR, KEY_SPEC_SESSION_KEYRING));
if (TEST_RETURN < 0) {
tst_brk(TBROK | TTERRNO,
"unable to clear keyring");
}
}
exit(0);
}
request_key_pid = SAFE_FORK();
if (request_key_pid == 0) {
for (i = 0; i < 5000 * effort; i++) {
TEST(request_key(type, "desc", "callout_info",
KEY_SPEC_SESSION_KEYRING));
if (TEST_RETURN < 0 && TEST_ERRNO != ENOKEY &&
TEST_ERRNO != ENOENT && TEST_ERRNO != EDQUOT) {
tst_brk(TBROK | TTERRNO,
"unexpected error requesting key of type '%s'",
type);
}
}
exit(0);
}
/*
* Verify that neither the add_key() nor the request_key() process
* crashed. If the add_key() process crashed it is likely due to
* CVE-2017-15299, while if the request_key() process crashed it is
* likely due to CVE-2017-15951. If testing for one of the bugs
* specifically, only pay attention to the corresponding process.
*/
SAFE_WAITPID(add_key_pid, &status, 0);
info_only = (opt_bug && strcmp(opt_bug, "cve-2017-15299") != 0);
if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
tst_res(info_only ? TINFO : TPASS,
"didn't crash while updating key of type '%s'",
type);
} else if (WIFSIGNALED(status) && WTERMSIG(status) == SIGKILL) {
tst_res(info_only ? TINFO : TFAIL,
"kernel oops while updating key of type '%s'",
type);
} else {
tst_brk(TBROK, "add_key child %s", tst_strstatus(status));
}
SAFE_WAITPID(request_key_pid, &status, 0);
info_only = (opt_bug && strcmp(opt_bug, "cve-2017-15951") != 0);
if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
tst_res(info_only ? TINFO : TPASS,
"didn't crash while requesting key of type '%s'",
type);
} else if (WIFSIGNALED(status) && WTERMSIG(status) == SIGKILL) {
tst_res(info_only ? TINFO : TFAIL,
"kernel oops while requesting key of type '%s'",
type);
} else {
tst_brk(TBROK, "request_key child %s", tst_strstatus(status));
}
}
static void do_test(void)
{
/*
* Briefly test the "encrypted" and/or "trusted" key types when
* availaible, mainly to reproduce CVE-2017-15299.
*/
test_with_key_type("encrypted", "update user:foo 32", 2);
test_with_key_type("trusted", "update", 2);
/*
* Test the "user" key type for longer, mainly in order to reproduce
* CVE-2017-15951. However, without the fix for CVE-2017-15299 as well,
* WARNs may show up in the kernel log.
*
* Note: the precise iteration count is arbitrary; it's just intended to
* be enough to give a decent chance of reproducing the bug, without
* wasting too much time.
*/
test_with_key_type("user", "payload", 20);
}
static struct tst_test test = {
.test_all = do_test,
.forks_child = 1,
.options = options,
};