1da177e4c3
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
359 lines
9.1 KiB
C
359 lines
9.1 KiB
C
/* request_key.c: request a key from userspace
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*
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* Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/module.h>
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#include <linux/sched.h>
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#include <linux/kmod.h>
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#include <linux/err.h>
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#include "internal.h"
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struct key_construction {
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struct list_head link; /* link in construction queue */
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struct key *key; /* key being constructed */
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};
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/* when waiting for someone else's keys, you get added to this */
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DECLARE_WAIT_QUEUE_HEAD(request_key_conswq);
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/*****************************************************************************/
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/*
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* request userspace finish the construction of a key
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* - execute "/sbin/request-key <op> <key> <uid> <gid> <keyring> <keyring> <keyring> <info>"
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* - if callout_info is an empty string, it'll be rendered as a "-" instead
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*/
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static int call_request_key(struct key *key,
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const char *op,
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const char *callout_info)
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{
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struct task_struct *tsk = current;
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unsigned long flags;
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key_serial_t prkey, sskey;
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char *argv[10], *envp[3], uid_str[12], gid_str[12];
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char key_str[12], keyring_str[3][12];
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int i;
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/* record the UID and GID */
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sprintf(uid_str, "%d", current->fsuid);
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sprintf(gid_str, "%d", current->fsgid);
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/* we say which key is under construction */
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sprintf(key_str, "%d", key->serial);
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/* we specify the process's default keyrings */
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sprintf(keyring_str[0], "%d",
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tsk->thread_keyring ? tsk->thread_keyring->serial : 0);
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prkey = 0;
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if (tsk->signal->process_keyring)
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prkey = tsk->signal->process_keyring->serial;
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sskey = 0;
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spin_lock_irqsave(&tsk->sighand->siglock, flags);
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if (tsk->signal->session_keyring)
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sskey = tsk->signal->session_keyring->serial;
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spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
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if (!sskey)
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sskey = tsk->user->session_keyring->serial;
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sprintf(keyring_str[1], "%d", prkey);
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sprintf(keyring_str[2], "%d", sskey);
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/* set up a minimal environment */
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i = 0;
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envp[i++] = "HOME=/";
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envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
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envp[i] = NULL;
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/* set up the argument list */
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i = 0;
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argv[i++] = "/sbin/request-key";
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argv[i++] = (char *) op;
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argv[i++] = key_str;
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argv[i++] = uid_str;
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argv[i++] = gid_str;
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argv[i++] = keyring_str[0];
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argv[i++] = keyring_str[1];
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argv[i++] = keyring_str[2];
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argv[i++] = callout_info[0] ? (char *) callout_info : "-";
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argv[i] = NULL;
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/* do it */
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return call_usermodehelper(argv[0], argv, envp, 1);
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} /* end call_request_key() */
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/*****************************************************************************/
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/*
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* call out to userspace for the key
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* - called with the construction sem held, but the sem is dropped here
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* - we ignore program failure and go on key status instead
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*/
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static struct key *__request_key_construction(struct key_type *type,
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const char *description,
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const char *callout_info)
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{
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struct key_construction cons;
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struct timespec now;
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struct key *key;
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int ret, negative;
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/* create a key and add it to the queue */
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key = key_alloc(type, description,
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current->fsuid, current->fsgid, KEY_USR_ALL, 0);
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if (IS_ERR(key))
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goto alloc_failed;
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write_lock(&key->lock);
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key->flags |= KEY_FLAG_USER_CONSTRUCT;
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write_unlock(&key->lock);
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cons.key = key;
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list_add_tail(&cons.link, &key->user->consq);
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/* we drop the construction sem here on behalf of the caller */
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up_write(&key_construction_sem);
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/* make the call */
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ret = call_request_key(key, "create", callout_info);
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if (ret < 0)
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goto request_failed;
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/* if the key wasn't instantiated, then we want to give an error */
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ret = -ENOKEY;
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if (!(key->flags & KEY_FLAG_INSTANTIATED))
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goto request_failed;
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down_write(&key_construction_sem);
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list_del(&cons.link);
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up_write(&key_construction_sem);
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/* also give an error if the key was negatively instantiated */
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check_not_negative:
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if (key->flags & KEY_FLAG_NEGATIVE) {
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key_put(key);
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key = ERR_PTR(-ENOKEY);
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}
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out:
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return key;
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request_failed:
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/* it wasn't instantiated
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* - remove from construction queue
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* - mark the key as dead
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*/
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negative = 0;
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down_write(&key_construction_sem);
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list_del(&cons.link);
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write_lock(&key->lock);
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key->flags &= ~KEY_FLAG_USER_CONSTRUCT;
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/* check it didn't get instantiated between the check and the down */
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if (!(key->flags & KEY_FLAG_INSTANTIATED)) {
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key->flags |= KEY_FLAG_INSTANTIATED | KEY_FLAG_NEGATIVE;
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negative = 1;
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}
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write_unlock(&key->lock);
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up_write(&key_construction_sem);
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if (!negative)
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goto check_not_negative; /* surprisingly, the key got
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* instantiated */
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/* set the timeout and store in the session keyring if we can */
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now = current_kernel_time();
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key->expiry = now.tv_sec + key_negative_timeout;
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if (current->signal->session_keyring) {
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unsigned long flags;
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struct key *keyring;
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spin_lock_irqsave(¤t->sighand->siglock, flags);
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keyring = current->signal->session_keyring;
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atomic_inc(&keyring->usage);
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spin_unlock_irqrestore(¤t->sighand->siglock, flags);
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key_link(keyring, key);
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key_put(keyring);
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}
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key_put(key);
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/* notify anyone who was waiting */
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wake_up_all(&request_key_conswq);
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key = ERR_PTR(ret);
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goto out;
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alloc_failed:
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up_write(&key_construction_sem);
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goto out;
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} /* end __request_key_construction() */
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/*****************************************************************************/
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/*
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* call out to userspace to request the key
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* - we check the construction queue first to see if an appropriate key is
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* already being constructed by userspace
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*/
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static struct key *request_key_construction(struct key_type *type,
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const char *description,
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struct key_user *user,
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const char *callout_info)
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{
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struct key_construction *pcons;
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struct key *key, *ckey;
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DECLARE_WAITQUEUE(myself, current);
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/* see if there's such a key under construction already */
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down_write(&key_construction_sem);
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list_for_each_entry(pcons, &user->consq, link) {
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ckey = pcons->key;
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if (ckey->type != type)
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continue;
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if (type->match(ckey, description))
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goto found_key_under_construction;
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}
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/* see about getting userspace to construct the key */
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key = __request_key_construction(type, description, callout_info);
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error:
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return key;
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/* someone else has the same key under construction
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* - we want to keep an eye on their key
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*/
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found_key_under_construction:
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atomic_inc(&ckey->usage);
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up_write(&key_construction_sem);
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/* wait for the key to be completed one way or another */
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add_wait_queue(&request_key_conswq, &myself);
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for (;;) {
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set_current_state(TASK_UNINTERRUPTIBLE);
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if (!(ckey->flags & KEY_FLAG_USER_CONSTRUCT))
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break;
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schedule();
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}
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set_current_state(TASK_RUNNING);
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remove_wait_queue(&request_key_conswq, &myself);
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/* we'll need to search this process's keyrings to see if the key is
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* now there since we can't automatically assume it's also available
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* there */
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key_put(ckey);
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ckey = NULL;
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key = NULL; /* request a retry */
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goto error;
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} /* end request_key_construction() */
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/*****************************************************************************/
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/*
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* request a key
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* - search the process's keyrings
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* - check the list of keys being created or updated
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* - call out to userspace for a key if requested (supplementary info can be
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* passed)
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*/
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struct key *request_key(struct key_type *type,
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const char *description,
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const char *callout_info)
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{
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struct key_user *user;
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struct key *key;
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/* search all the process keyrings for a key */
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key = search_process_keyrings_aux(type, description, type->match);
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if (PTR_ERR(key) == -EAGAIN) {
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/* the search failed, but the keyrings were searchable, so we
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* should consult userspace if we can */
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key = ERR_PTR(-ENOKEY);
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if (!callout_info)
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goto error;
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/* - get hold of the user's construction queue */
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user = key_user_lookup(current->fsuid);
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if (!user) {
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key = ERR_PTR(-ENOMEM);
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goto error;
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}
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for (;;) {
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/* ask userspace (returns NULL if it waited on a key
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* being constructed) */
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key = request_key_construction(type, description,
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user, callout_info);
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if (key)
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break;
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/* someone else made the key we want, so we need to
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* search again as it might now be available to us */
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key = search_process_keyrings_aux(type, description,
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type->match);
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if (PTR_ERR(key) != -EAGAIN)
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break;
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}
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key_user_put(user);
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}
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error:
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return key;
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} /* end request_key() */
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EXPORT_SYMBOL(request_key);
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/*****************************************************************************/
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/*
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* validate a key
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*/
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int key_validate(struct key *key)
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{
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struct timespec now;
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int ret = 0;
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if (key) {
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/* check it's still accessible */
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ret = -EKEYREVOKED;
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if (key->flags & (KEY_FLAG_REVOKED | KEY_FLAG_DEAD))
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goto error;
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/* check it hasn't expired */
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ret = 0;
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if (key->expiry) {
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now = current_kernel_time();
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if (now.tv_sec >= key->expiry)
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ret = -EKEYEXPIRED;
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}
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}
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error:
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return ret;
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} /* end key_validate() */
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EXPORT_SYMBOL(key_validate);
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