--- /dev/null
+/* request_key.c: request a key from userspace
+ *
+ * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * 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.
+ */
+
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/kmod.h>
+#include <linux/err.h>
+#include "internal.h"
+
+struct key_construction {
+ struct list_head link; /* link in construction queue */
+ struct key *key; /* key being constructed */
+};
+
+/* when waiting for someone else's keys, you get added to this */
+DECLARE_WAIT_QUEUE_HEAD(request_key_conswq);
+
+/*****************************************************************************/
+/*
+ * request userspace finish the construction of a key
+ * - execute "/sbin/request-key <op> <key> <uid> <gid> <keyring> <keyring> <keyring> <info>"
+ * - if callout_info is an empty string, it'll be rendered as a "-" instead
+ */
+static int call_request_key(struct key *key,
+ const char *op,
+ const char *callout_info)
+{
+ struct task_struct *tsk = current;
+ char *argv[10], *envp[3], uid_str[12], gid_str[12];
+ char key_str[12], keyring_str[3][12];
+ int i;
+
+ /* record the UID and GID */
+ sprintf(uid_str, "%d", current->fsuid);
+ sprintf(gid_str, "%d", current->fsgid);
+
+ /* we say which key is under construction */
+ sprintf(key_str, "%d", key->serial);
+
+ /* we specify the process's default keyrings */
+ task_lock(current);
+ sprintf(keyring_str[0], "%d",
+ tsk->thread_keyring ? tsk->thread_keyring->serial : 0);
+ sprintf(keyring_str[1], "%d",
+ tsk->process_keyring ? tsk->process_keyring->serial : 0);
+ sprintf(keyring_str[2], "%d",
+ (tsk->session_keyring ?
+ tsk->session_keyring->serial :
+ tsk->user->session_keyring->serial));
+ task_unlock(tsk);
+
+ /* 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++] = callout_info[0] ? (char *) callout_info : "-";
+ argv[i] = NULL;
+
+ /* do it */
+ return call_usermodehelper(argv[0], argv, envp, 1);
+
+} /* end call_request_key() */
+
+/*****************************************************************************/
+/*
+ * call out to userspace for the key
+ * - called with the construction sem held, but the sem is dropped here
+ * - we ignore program failure and go on key status instead
+ */
+static struct key *__request_key_construction(struct key_type *type,
+ const char *description,
+ const char *callout_info)
+{
+ struct key_construction cons;
+ struct timespec now;
+ struct key *key;
+ int ret, negative;
+
+ /* create a key and add it to the queue */
+ key = key_alloc(type, description,
+ current->fsuid, current->fsgid, KEY_USR_ALL, 0);
+ if (IS_ERR(key))
+ goto alloc_failed;
+
+ write_lock(&key->lock);
+ key->flags |= KEY_FLAG_USER_CONSTRUCT;
+ write_unlock(&key->lock);
+
+ cons.key = key;
+ list_add_tail(&cons.link, &key->user->consq);
+
+ /* we drop the construction sem here on behalf of the caller */
+ up_write(&key_construction_sem);
+
+ /* make the call */
+ ret = call_request_key(key, "create", callout_info);
+ if (ret < 0)
+ goto request_failed;
+
+ /* if the key wasn't instantiated, then we want to give an error */
+ ret = -ENOKEY;
+ if (!(key->flags & KEY_FLAG_INSTANTIATED))
+ goto request_failed;
+
+ down_write(&key_construction_sem);
+ list_del(&cons.link);
+ up_write(&key_construction_sem);
+
+ /* also give an error if the key was negatively instantiated */
+ check_not_negative:
+ if (key->flags & KEY_FLAG_NEGATIVE) {
+ key_put(key);
+ key = ERR_PTR(-ENOKEY);
+ }
+
+ out:
+ return key;
+
+ request_failed:
+ /* it wasn't instantiated
+ * - remove from construction queue
+ * - mark the key as dead
+ */
+ negative = 0;
+ down_write(&key_construction_sem);
+
+ list_del(&cons.link);
+
+ write_lock(&key->lock);
+ key->flags &= ~KEY_FLAG_USER_CONSTRUCT;
+
+ /* check it didn't get instantiated between the check and the down */
+ if (!(key->flags & KEY_FLAG_INSTANTIATED)) {
+ key->flags |= KEY_FLAG_INSTANTIATED | KEY_FLAG_NEGATIVE;
+ negative = 1;
+ }
+
+ write_unlock(&key->lock);
+ up_write(&key_construction_sem);
+
+ if (!negative)
+ goto check_not_negative; /* surprisingly, the key got
+ * instantiated */
+
+ /* set the timeout and store in the session keyring if we can */
+ now = current_kernel_time();
+ key->expiry = now.tv_sec + key_negative_timeout;
+
+ if (current->session_keyring)
+ key_link(current->session_keyring, key);
+ key_put(key);
+
+ /* notify anyone who was waiting */
+ wake_up_all(&request_key_conswq);
+
+ key = ERR_PTR(ret);
+ goto out;
+
+ alloc_failed:
+ up_write(&key_construction_sem);
+ goto out;
+
+} /* end __request_key_construction() */
+
+/*****************************************************************************/
+/*
+ * call out to userspace to request the key
+ * - we check the construction queue first to see if an appropriate key is
+ * already being constructed by userspace
+ */
+static struct key *request_key_construction(struct key_type *type,
+ const char *description,
+ struct key_user *user,
+ const char *callout_info)
+{
+ struct key_construction *pcons;
+ struct key *key, *ckey;
+
+ DECLARE_WAITQUEUE(myself, current);
+
+ /* see if there's such a key under construction already */
+ down_write(&key_construction_sem);
+
+ list_for_each_entry(pcons, &user->consq, link) {
+ ckey = pcons->key;
+
+ if (ckey->type != type)
+ continue;
+
+ if (type->match(ckey, description))
+ goto found_key_under_construction;
+ }
+
+ /* see about getting userspace to construct the key */
+ key = __request_key_construction(type, description, callout_info);
+ error:
+ return key;
+
+ /* someone else has the same key under construction
+ * - we want to keep an eye on their key
+ */
+ found_key_under_construction:
+ atomic_inc(&ckey->usage);
+ up_write(&key_construction_sem);
+
+ /* wait for the key to be completed one way or another */
+ add_wait_queue(&request_key_conswq, &myself);
+
+ for (;;) {
+ set_current_state(TASK_UNINTERRUPTIBLE);
+ if (!(ckey->flags & KEY_FLAG_USER_CONSTRUCT))
+ break;
+ schedule();
+ }
+
+ set_current_state(TASK_RUNNING);
+ remove_wait_queue(&request_key_conswq, &myself);
+
+ /* we'll need to search this process's keyrings to see if the key is
+ * now there since we can't automatically assume it's also available
+ * there */
+ key_put(ckey);
+ ckey = NULL;
+
+ key = NULL; /* request a retry */
+ goto error;
+
+} /* end request_key_construction() */
+
+/*****************************************************************************/
+/*
+ * request a key
+ * - search the process's keyrings
+ * - check the list of keys being created or updated
+ * - call out to userspace for a key if requested (supplementary info can be
+ * passed)
+ */
+struct key *request_key(struct key_type *type,
+ const char *description,
+ const char *callout_info)
+{
+ struct key_user *user;
+ struct key *key;
+
+ /* search all the process keyrings for a key */
+ key = search_process_keyrings_aux(type, description, type->match);
+
+ if (PTR_ERR(key) == -EAGAIN) {
+ /* the search failed, but the keyrings were searchable, so we
+ * should consult userspace if we can */
+ key = ERR_PTR(-ENOKEY);
+ if (!callout_info)
+ goto error;
+
+ /* - get hold of the user's construction queue */
+ user = key_user_lookup(current->fsuid);
+ if (IS_ERR(user)) {
+ key = ERR_PTR(PTR_ERR(user));
+ goto error;
+ }
+
+ for (;;) {
+ /* ask userspace (returns NULL if it waited on a key
+ * being constructed) */
+ key = request_key_construction(type, description,
+ user, callout_info);
+ if (key)
+ break;
+
+ /* someone else made the key we want, so we need to
+ * search again as it might now be available to us */
+ key = search_process_keyrings_aux(type, description,
+ type->match);
+ if (PTR_ERR(key) != -EAGAIN)
+ break;
+ }
+
+ key_user_put(user);
+ }
+
+ error:
+ return key;
+
+} /* end request_key() */
+
+EXPORT_SYMBOL(request_key);
+
+/*****************************************************************************/
+/*
+ * validate a key
+ */
+int key_validate(struct key *key)
+{
+ struct timespec now;
+ int ret = 0;
+
+ if (key) {
+ /* check it's still accessible */
+ ret = -EKEYREVOKED;
+ if (key->flags & (KEY_FLAG_REVOKED | KEY_FLAG_DEAD))
+ goto error;
+
+ /* check it hasn't expired */
+ ret = 0;
+ if (key->expiry) {
+ now = current_kernel_time();
+ if (now.tv_sec >= key->expiry)
+ ret = -EKEYEXPIRED;
+ }
+ }
+
+ error:
+ return ret;
+
+} /* end key_validate() */
+
+EXPORT_SYMBOL(key_validate);
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