static int call_sbin_request_key(struct key_construction *cons,
				 const char *op,
				 void *aux)
{
	const struct cred *cred = current_cred();
	key_serial_t prkey, sskey;
	struct key *key = cons->key, *authkey = cons->authkey, *keyring,
		*session;
	char *argv[9], *envp[3], uid_str[12], gid_str[12];
	char key_str[12], keyring_str[3][12];
	char desc[20];
	int ret, i;

	kenter("{%d},{%d},%s", key->serial, authkey->serial, op);

	ret = install_user_keyrings();
	if (ret < 0)
		goto error_alloc;

	/* allocate a new session keyring */
	sprintf(desc, "_req.%u", key->serial);

	cred = get_current_cred();
	keyring = keyring_alloc(desc, cred->fsuid, cred->fsgid, cred,
				KEY_ALLOC_QUOTA_OVERRUN, NULL);
	put_cred(cred);
	if (IS_ERR(keyring)) {
		ret = PTR_ERR(keyring);
		goto error_alloc;
	}

	/* attach the auth key to the session keyring */
	ret = key_link(keyring, authkey);
	if (ret < 0)
		goto error_link;

	/* record the UID and GID */
	sprintf(uid_str, "%d", cred->fsuid);
	sprintf(gid_str, "%d", cred->fsgid);

	/* we say which key is under construction */
	sprintf(key_str, "%d", key->serial);

	/* we specify the process's default keyrings */
	sprintf(keyring_str[0], "%d",
		cred->thread_keyring ? cred->thread_keyring->serial : 0);

	prkey = 0;
	if (cred->process_keyring)
		prkey = cred->process_keyring->serial;
	sprintf(keyring_str[1], "%d", prkey);

	rcu_read_lock();
	session = rcu_dereference(cred->session_keyring);
	if (!session)
		session = cred->user->session_keyring;
	sskey = session->serial;
	rcu_read_unlock();

	sprintf(keyring_str[2], "%d", sskey);

	/* set up a minimal environment */
	i = 0;
	envp[i++] = "HOME=/";
	envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
	envp[i] = NULL;

	/* set up the argument list */
	i = 0;
	argv[i++] = "/sbin/request-key";
	argv[i++] = (char *) op;
	argv[i++] = key_str;
	argv[i++] = uid_str;
	argv[i++] = gid_str;
	argv[i++] = keyring_str[0];
	argv[i++] = keyring_str[1];
	argv[i++] = keyring_str[2];
	argv[i] = NULL;

	/* do it */
	ret = call_usermodehelper_keys(argv[0], argv, envp, keyring,
				       UMH_WAIT_PROC);
	kdebug("usermode -> 0x%x", ret);
	if (ret >= 0) {
		/* ret is the exit/wait code */
		if (test_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags) ||
		    key_validate(key) < 0)
			ret = -ENOKEY;
		else
			/* ignore any errors from userspace if the key was
			 * instantiated */
			ret = 0;
	}

error_link:
	key_put(keyring);

error_alloc:
	complete_request_key(cons, ret);
	kleave(" = %d", ret);
	return ret;
}
Unknown