/* Request a key from userspace
*
* Copyright (C) 2004-2007 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.
*
* See Documentation/keys-request-key.txt
*/
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/kmod.h>
#include <linux/err.h>
#include <linux/keyctl.h>
#include <linux/slab.h>
#include "internal.h"
#define key_negative_timeout 60 /* default timeout on a negative key's existence */
/*
* wait_on_bit() sleep function for uninterruptible waiting
*/
static int key_wait_bit(void *flags)
{
schedule();
return 0;
}
/*
* wait_on_bit() sleep function for interruptible waiting
*/
static int key_wait_bit_intr(void *flags)
{
schedule();
return signal_pending(current) ? -ERESTARTSYS : 0;
}
/*
* call to complete the construction of a key
*/
void complete_request_key(struct key_construction *cons, int error)
{
kenter("{%d,%d},%d", cons->key->serial, cons->authkey->serial, error);
if (error < 0)
key_negate_and_link(cons->key, key_negative_timeout, NULL,
cons->authkey);
else
key_revoke(cons->authkey);
key_put(cons->key);
key_put(cons->authkey);
kfree(cons);
}
EXPORT_SYMBOL(complete_request_key);
/*
* request userspace finish the construction of a key
* - execute "/sbin/request-key <op> <key> <uid> <gid> <keyring> <keyring> <keyring>"
*/
static int call_sbin_request_key(struct key_construction *cons,
const char *op,
void *aux)
{
struct task_struct *tsk = current;
key_serial_t prkey, sskey;
struct key *key = cons->key, *authkey = cons->authkey, *keyring;
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);
keyring = keyring_alloc(desc, current_fsuid(), current_fsgid(), current,
KEY_ALLOC_QUOTA_OVERRUN, NULL);
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", 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 */
sprintf(keyring_str[0], "%d",
tsk->cred->thread_keyring ?
tsk->cred->thread_keyring->serial : 0);
prkey = 0;
if (tsk->signal->process_keyring)
prkey = tsk->signal->process_keyring->serial;
sprintf(keyring_str[1], "%d", prkey);
if (tsk->signal->session_keyring) {
rcu_read_lock();
sskey = rcu_dereference(tsk->signal->session_keyring)->serial;
rcu_read_unlock();
} else {
sskey = tsk->cred->user->session_keyring->serial;
}
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:
kleave(" = %d", ret);
complete_request_key(cons, ret);
return ret;
}
/*
* call out to userspace for key construction
* - we ignore program failure and go on key status instead
*/
static int construct_key(struct key *key, const void *callout_info,
size_t callout_len, void *aux,
struct key *dest_keyring)
{
struct key_construction *cons;
request_key_actor_t actor;
struct key *authkey;
int ret;
kenter("%d,%p,%zu,%p", key->serial, callout_info, callout_len, aux);
cons = kmalloc(sizeof(*cons), GFP_KERNEL);
if (!cons)
return -ENOMEM;
/* allocate an authorisation key */
authkey = request_key_auth_new(key, callout_info, callout_len,
dest_keyring);
if (IS_ERR(authkey)) {
kfree(cons);
ret = PTR_ERR(authkey);
authkey = NULL;
} else {
cons->authkey = key_get(authkey);
cons->key = key_get(key);
/* make the call */
actor = call_sbin_request_key;
if (key->type->request_key)
actor = key->type->request_key;
ret = actor(cons, "create", aux);
/* check that the actor called complete_request_key() prior to
* returning an error */
WARN_ON(ret < 0 &&
!test_bit(KEY_FLAG_REVOKED, &authkey->flags));
key_put(authkey);
}
kleave(" = %d", ret);
return ret;
}
/*
* get the appropriate destination keyring for the request
* - we return whatever keyring we select with an extra reference upon it which
* the caller must release
*/
static void construct_get_dest_keyring(struct key **_dest_keyring)
{
struct request_key_auth *rka;
struct task_struct *tsk = current;
struct key *dest_keyring = *_dest_keyring, *authkey;
kenter("%p", dest_keyring);
/* find the appropriate keyring */
if (dest_keyring) {
/* the caller supplied one */
key_get(dest_keyring);
} else {
/* use a default keyring; falling through the cases until we
* find one that we actually have */
switch (tsk->cred->jit_keyring) {
case KEY_REQKEY_DEFL_DEFAULT:
case KEY_REQKEY_DEFL_REQUESTOR_KEYRING:
if (tsk->cred->request_key_auth) {
authkey = tsk->cred->request_key_auth;
down_read(&authkey->sem);
rka = authkey->payload.data;
if (!test_bit(KEY_FLAG_REVOKED,
&authkey->flags))
dest_keyring =
key_get(rka->dest_keyring);
up_read(&authkey->sem);
if (dest_keyring)
break;
}
case KEY_REQKEY_DEFL_THREAD_KEYRING:
dest_keyring = key_get(tsk->cred->thread_keyring);
if (dest_keyring)
break;
case KEY_REQKEY_DEFL_PROCESS_KEYRING:
dest_keyring = key_get(tsk->signal->process_keyring);
if (dest_keyring)
break;
case KEY_REQKEY_DEFL_SESSION_KEYRING:
rcu_read_lock();
dest_keyring = key_get(
rcu_dereference(tsk->signal->session_keyring));
rcu_read_unlock();
if (dest_keyring)
break;
case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
dest_keyring =
key_get(tsk->cred->user->session_keyring);
break;
case KEY_REQKEY_DEFL_USER_KEYRING:
dest_keyring = key_get(tsk->cred->user->uid_keyring);
break;
case KEY_REQKEY_DEFL_GROUP_KEYRING:
default:
BUG();
}
}
*_dest_keyring = dest_keyring;
kleave(" [dk %d]", key_serial(dest_keyring));
return;
}
/*
* allocate a new key in under-construction state and attempt to link it in to
* the requested place
* - may return a key that's already under construction instead
*/
static int construct_alloc_key(struct key_type *type,
const char *description,
struct key *dest_keyring,
unsigned long flags,
struct key_user *user,
struct key **_key)
{
struct key *key;
key_ref_t key_ref;
kenter("%s,%s,,,", type->name, description);
mutex_lock(&user->cons_lock);
key = key_alloc(type, description,
current_fsuid(), current_fsgid(), current, KEY_POS_ALL,
flags);
if (IS_ERR(key))
goto alloc_failed;
set_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags);
down_write(&dest_keyring->sem);
/* attach the key to the destination keyring under lock, but we do need
* to do another check just in case someone beat us to it whilst we
* waited for locks */
mutex_lock(&key_construction_mutex);
key_ref = search_process_keyrings(type, description, type->match,
current);
if (!IS_ERR(key_ref))
goto key_already_present;
__key_link(dest_keyring, key);
mutex_unlock(&key_construction_mutex);
up_write(&dest_keyring->sem);
mutex_unlock(&user->cons_lock);
*_key = key;
kleave(" = 0 [%d]", key_serial(key));
return 0;
key_already_present:
mutex_unlock(&key_construction_mutex);
if (dest_keyring)
up_write(&dest_keyring->sem);
mutex_unlock(&user->cons_lock);
key_put(key);
*_key = key = key_ref_to_ptr(key_ref);
kleave(" = -EINPROGRESS [%d]", key_serial(key));
return -EINPROGRESS;
alloc_failed:
mutex_unlock(&user->cons_lock);
*_key = NULL;
kleave(" = %ld", PTR_ERR(key));
return PTR_ERR(key);
}
/*
* commence key construction
*/
static struct key *construct_key_and_link(struct key_type *type,
const char *description,
const char *callout_info,
size_t callout_len,
void *aux,
struct key *dest_keyring,
unsigned long flags)
{
struct key_user *user;
struct key *key;
int ret;
user = key_user_lookup(current_fsuid());
if (!user)
return ERR_PTR(-ENOMEM);
construct_get_dest_keyring(&dest_keyring);
ret = construct_alloc_key(type, description, dest_keyring, flags, user,
&key);
key_user_put(user);
if (ret == 0) {
ret = construct_key(key, callout_info, callout_len, aux,
dest_keyring);
if (ret < 0)
goto construction_failed;
}
key_put(dest_keyring);
return key;
construction_failed:
key_negate_and_link(key, key_negative_timeout, NULL, NULL);
key_put(key);
key_put(dest_keyring);
return ERR_PTR(ret);
}
/*
* 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 supplementary info was provided
* - cache the key in an appropriate keyring
*/
struct key *request_key_and_link(struct key_type *type,
const char *description,
const void *callout_info,
size_t callout_len,
void *aux,
struct key *dest_keyring,
unsigned long flags)
{
struct key *key;
key_ref_t key_ref;
kenter("%s,%s,%p,%zu,%p,%p,%lx",
type->name, description, callout_info, callout_len, aux,
dest_keyring, flags);
/* search all the process keyrings for a key */
key_ref = search_process_keyrings(type, description, type->match,
current);
if (!IS_ERR(key_ref)) {
key = key_ref_to_ptr(key_ref);
} else if (PTR_ERR(key_ref) != -EAGAIN) {
key = ERR_CAST(key_ref);
} else {
/* 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;
key = construct_key_and_link(type, description, callout_info,
callout_len, aux, dest_keyring,
flags);
}
error:
kleave(" = %p", key);
return key;
}
/*
* wait for construction of a key to complete
*/
int wait_for_key_construction(struct key *key, bool intr)
{
int ret;
ret = wait_on_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT,
intr ? key_wait_bit_intr : key_wait_bit,
intr ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE);
if (ret < 0)
return ret;
return key_validate(key);
}
EXPORT_SYMBOL(wait_for_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 supplementary info was provided
* - waits uninterruptible for creation to complete
*/
struct key *request_key(struct key_type *type,
const char *description,
const char *callout_info)
{
struct key *key;
size_t callout_len = 0;
int ret;
if (callout_info)
callout_len = strlen(callout_info);
key = request_key_and_link(type, description, callout_info, callout_len,
NULL, NULL, KEY_ALLOC_IN_QUOTA);
if (!IS_ERR(key)) {
ret = wait_for_key_construction(key, false);
if (ret < 0) {
key_put(key);
return ERR_PTR(ret);
}
}
return key;
}
EXPORT_SYMBOL(request_key);
/*
* request a key with auxiliary data for the upcaller
* - search the process's keyrings
* - check the list of keys being created or updated
* - call out to userspace for a key if supplementary info was provided
* - waits uninterruptible for creation to complete
*/
struct key *request_key_with_auxdata(struct key_type *type,
const char *description,
const void *callout_info,
size_t callout_len,
void *aux)
{
struct key *key;
int ret;
key = request_key_and_link(type, description, callout_info, callout_len,
aux, NULL, KEY_ALLOC_IN_QUOTA);
if (!IS_ERR(key)) {
ret = wait_for_key_construction(key, false);
if (ret < 0) {
key_put(key);
return ERR_PTR(ret);
}
}
return key;
}
EXPORT_SYMBOL(request_key_with_auxdata);
/*
* request a key (allow async construction)
* - search the process's keyrings
* - check the list of keys being created or updated
* - call out to userspace for a key if supplementary info was provided
*/
struct key *request_key_async(struct key_type *type,
const char *description,
const void *callout_info,
size_t callout_len)
{
return request_key_and_link(type, description, callout_info,
callout_len, NULL, NULL,
KEY_ALLOC_IN_QUOTA);
}
EXPORT_SYMBOL(request_key_async);
/*
* request a key with auxiliary data for the upcaller (allow async construction)
* - search the process's keyrings
* - check the list of keys being created or updated
* - call out to userspace for a key if supplementary info was provided
*/
struct key *request_key_async_with_auxdata(struct key_type *type,
const char *description,
const void *callout_info,
size_t callout_len,
void *aux)
{
return request_key_and_link(type, description, callout_info,
callout_len, aux, NULL, KEY_ALLOC_IN_QUOTA);
}
EXPORT_SYMBOL(request_key_async_with_auxdata);
