kernel-ark/crypto/api.c
Herbert Xu da7cd59ab9 [CRYPTO] api: Read module pointer before freeing algorithm
The function crypto_mod_put first frees the algorithm and then drops
the reference to its module.  Unfortunately we read the module pointer
which after freeing the algorithm and that pointer sits inside the
object that we just freed.

So this patch reads the module pointer out before we free the object.

Thanks to Luca Tettamanti for reporting this.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2007-05-19 14:51:00 +10:00

439 lines
9.4 KiB
C

/*
* Scatterlist Cryptographic API.
*
* Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
* Copyright (c) 2002 David S. Miller (davem@redhat.com)
* Copyright (c) 2005 Herbert Xu <herbert@gondor.apana.org.au>
*
* Portions derived from Cryptoapi, by Alexander Kjeldaas <astor@fast.no>
* and Nettle, by Niels Möller.
*
* 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/err.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/kmod.h>
#include <linux/module.h>
#include <linux/param.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/string.h>
#include "internal.h"
LIST_HEAD(crypto_alg_list);
EXPORT_SYMBOL_GPL(crypto_alg_list);
DECLARE_RWSEM(crypto_alg_sem);
EXPORT_SYMBOL_GPL(crypto_alg_sem);
BLOCKING_NOTIFIER_HEAD(crypto_chain);
EXPORT_SYMBOL_GPL(crypto_chain);
static inline struct crypto_alg *crypto_alg_get(struct crypto_alg *alg)
{
atomic_inc(&alg->cra_refcnt);
return alg;
}
struct crypto_alg *crypto_mod_get(struct crypto_alg *alg)
{
return try_module_get(alg->cra_module) ? crypto_alg_get(alg) : NULL;
}
EXPORT_SYMBOL_GPL(crypto_mod_get);
void crypto_mod_put(struct crypto_alg *alg)
{
struct module *module = alg->cra_module;
crypto_alg_put(alg);
module_put(module);
}
EXPORT_SYMBOL_GPL(crypto_mod_put);
struct crypto_alg *__crypto_alg_lookup(const char *name, u32 type, u32 mask)
{
struct crypto_alg *q, *alg = NULL;
int best = -2;
list_for_each_entry(q, &crypto_alg_list, cra_list) {
int exact, fuzzy;
if (crypto_is_moribund(q))
continue;
if ((q->cra_flags ^ type) & mask)
continue;
if (crypto_is_larval(q) &&
((struct crypto_larval *)q)->mask != mask)
continue;
exact = !strcmp(q->cra_driver_name, name);
fuzzy = !strcmp(q->cra_name, name);
if (!exact && !(fuzzy && q->cra_priority > best))
continue;
if (unlikely(!crypto_mod_get(q)))
continue;
best = q->cra_priority;
if (alg)
crypto_mod_put(alg);
alg = q;
if (exact)
break;
}
return alg;
}
EXPORT_SYMBOL_GPL(__crypto_alg_lookup);
static void crypto_larval_destroy(struct crypto_alg *alg)
{
struct crypto_larval *larval = (void *)alg;
BUG_ON(!crypto_is_larval(alg));
if (larval->adult)
crypto_mod_put(larval->adult);
kfree(larval);
}
static struct crypto_alg *crypto_larval_alloc(const char *name, u32 type,
u32 mask)
{
struct crypto_alg *alg;
struct crypto_larval *larval;
larval = kzalloc(sizeof(*larval), GFP_KERNEL);
if (!larval)
return ERR_PTR(-ENOMEM);
larval->mask = mask;
larval->alg.cra_flags = CRYPTO_ALG_LARVAL | type;
larval->alg.cra_priority = -1;
larval->alg.cra_destroy = crypto_larval_destroy;
atomic_set(&larval->alg.cra_refcnt, 2);
strlcpy(larval->alg.cra_name, name, CRYPTO_MAX_ALG_NAME);
init_completion(&larval->completion);
down_write(&crypto_alg_sem);
alg = __crypto_alg_lookup(name, type, mask);
if (!alg) {
alg = &larval->alg;
list_add(&alg->cra_list, &crypto_alg_list);
}
up_write(&crypto_alg_sem);
if (alg != &larval->alg)
kfree(larval);
return alg;
}
static void crypto_larval_kill(struct crypto_alg *alg)
{
struct crypto_larval *larval = (void *)alg;
down_write(&crypto_alg_sem);
list_del(&alg->cra_list);
up_write(&crypto_alg_sem);
complete(&larval->completion);
crypto_alg_put(alg);
}
static struct crypto_alg *crypto_larval_wait(struct crypto_alg *alg)
{
struct crypto_larval *larval = (void *)alg;
wait_for_completion_interruptible_timeout(&larval->completion, 60 * HZ);
alg = larval->adult;
if (alg) {
if (!crypto_mod_get(alg))
alg = ERR_PTR(-EAGAIN);
} else
alg = ERR_PTR(-ENOENT);
crypto_mod_put(&larval->alg);
return alg;
}
static struct crypto_alg *crypto_alg_lookup(const char *name, u32 type,
u32 mask)
{
struct crypto_alg *alg;
down_read(&crypto_alg_sem);
alg = __crypto_alg_lookup(name, type, mask);
up_read(&crypto_alg_sem);
return alg;
}
struct crypto_alg *crypto_alg_mod_lookup(const char *name, u32 type, u32 mask)
{
struct crypto_alg *alg;
struct crypto_alg *larval;
int ok;
if (!name)
return ERR_PTR(-ENOENT);
mask &= ~(CRYPTO_ALG_LARVAL | CRYPTO_ALG_DEAD);
type &= mask;
alg = try_then_request_module(crypto_alg_lookup(name, type, mask),
name);
if (alg)
return crypto_is_larval(alg) ? crypto_larval_wait(alg) : alg;
larval = crypto_larval_alloc(name, type, mask);
if (IS_ERR(larval) || !crypto_is_larval(larval))
return larval;
ok = crypto_notify(CRYPTO_MSG_ALG_REQUEST, larval);
if (ok == NOTIFY_DONE) {
request_module("cryptomgr");
ok = crypto_notify(CRYPTO_MSG_ALG_REQUEST, larval);
}
if (ok == NOTIFY_STOP)
alg = crypto_larval_wait(larval);
else {
crypto_mod_put(larval);
alg = ERR_PTR(-ENOENT);
}
crypto_larval_kill(larval);
return alg;
}
EXPORT_SYMBOL_GPL(crypto_alg_mod_lookup);
static int crypto_init_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
{
const struct crypto_type *type_obj = tfm->__crt_alg->cra_type;
if (type_obj)
return type_obj->init(tfm, type, mask);
switch (crypto_tfm_alg_type(tfm)) {
case CRYPTO_ALG_TYPE_CIPHER:
return crypto_init_cipher_ops(tfm);
case CRYPTO_ALG_TYPE_DIGEST:
return crypto_init_digest_ops(tfm);
case CRYPTO_ALG_TYPE_COMPRESS:
return crypto_init_compress_ops(tfm);
default:
break;
}
BUG();
return -EINVAL;
}
static void crypto_exit_ops(struct crypto_tfm *tfm)
{
const struct crypto_type *type = tfm->__crt_alg->cra_type;
if (type) {
if (type->exit)
type->exit(tfm);
return;
}
switch (crypto_tfm_alg_type(tfm)) {
case CRYPTO_ALG_TYPE_CIPHER:
crypto_exit_cipher_ops(tfm);
break;
case CRYPTO_ALG_TYPE_DIGEST:
crypto_exit_digest_ops(tfm);
break;
case CRYPTO_ALG_TYPE_COMPRESS:
crypto_exit_compress_ops(tfm);
break;
default:
BUG();
}
}
static unsigned int crypto_ctxsize(struct crypto_alg *alg, u32 type, u32 mask)
{
const struct crypto_type *type_obj = alg->cra_type;
unsigned int len;
len = alg->cra_alignmask & ~(crypto_tfm_ctx_alignment() - 1);
if (type_obj)
return len + type_obj->ctxsize(alg, type, mask);
switch (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) {
default:
BUG();
case CRYPTO_ALG_TYPE_CIPHER:
len += crypto_cipher_ctxsize(alg);
break;
case CRYPTO_ALG_TYPE_DIGEST:
len += crypto_digest_ctxsize(alg);
break;
case CRYPTO_ALG_TYPE_COMPRESS:
len += crypto_compress_ctxsize(alg);
break;
}
return len;
}
void crypto_shoot_alg(struct crypto_alg *alg)
{
down_write(&crypto_alg_sem);
alg->cra_flags |= CRYPTO_ALG_DYING;
up_write(&crypto_alg_sem);
}
EXPORT_SYMBOL_GPL(crypto_shoot_alg);
struct crypto_tfm *__crypto_alloc_tfm(struct crypto_alg *alg, u32 type,
u32 mask)
{
struct crypto_tfm *tfm = NULL;
unsigned int tfm_size;
int err = -ENOMEM;
tfm_size = sizeof(*tfm) + crypto_ctxsize(alg, type, mask);
tfm = kzalloc(tfm_size, GFP_KERNEL);
if (tfm == NULL)
goto out_err;
tfm->__crt_alg = alg;
err = crypto_init_ops(tfm, type, mask);
if (err)
goto out_free_tfm;
if (alg->cra_init && (err = alg->cra_init(tfm))) {
if (err == -EAGAIN)
crypto_shoot_alg(alg);
goto cra_init_failed;
}
goto out;
cra_init_failed:
crypto_exit_ops(tfm);
out_free_tfm:
kfree(tfm);
out_err:
tfm = ERR_PTR(err);
out:
return tfm;
}
EXPORT_SYMBOL_GPL(__crypto_alloc_tfm);
/*
* crypto_alloc_base - Locate algorithm and allocate transform
* @alg_name: Name of algorithm
* @type: Type of algorithm
* @mask: Mask for type comparison
*
* crypto_alloc_base() will first attempt to locate an already loaded
* algorithm. If that fails and the kernel supports dynamically loadable
* modules, it will then attempt to load a module of the same name or
* alias. If that fails it will send a query to any loaded crypto manager
* to construct an algorithm on the fly. A refcount is grabbed on the
* algorithm which is then associated with the new transform.
*
* The returned transform is of a non-determinate type. Most people
* should use one of the more specific allocation functions such as
* crypto_alloc_blkcipher.
*
* In case of error the return value is an error pointer.
*/
struct crypto_tfm *crypto_alloc_base(const char *alg_name, u32 type, u32 mask)
{
struct crypto_tfm *tfm;
int err;
for (;;) {
struct crypto_alg *alg;
alg = crypto_alg_mod_lookup(alg_name, type, mask);
if (IS_ERR(alg)) {
err = PTR_ERR(alg);
goto err;
}
tfm = __crypto_alloc_tfm(alg, type, mask);
if (!IS_ERR(tfm))
return tfm;
crypto_mod_put(alg);
err = PTR_ERR(tfm);
err:
if (err != -EAGAIN)
break;
if (signal_pending(current)) {
err = -EINTR;
break;
}
}
return ERR_PTR(err);
}
EXPORT_SYMBOL_GPL(crypto_alloc_base);
/*
* crypto_free_tfm - Free crypto transform
* @tfm: Transform to free
*
* crypto_free_tfm() frees up the transform and any associated resources,
* then drops the refcount on the associated algorithm.
*/
void crypto_free_tfm(struct crypto_tfm *tfm)
{
struct crypto_alg *alg;
int size;
if (unlikely(!tfm))
return;
alg = tfm->__crt_alg;
size = sizeof(*tfm) + alg->cra_ctxsize;
if (alg->cra_exit)
alg->cra_exit(tfm);
crypto_exit_ops(tfm);
crypto_mod_put(alg);
memset(tfm, 0, size);
kfree(tfm);
}
EXPORT_SYMBOL_GPL(crypto_free_tfm);
int crypto_has_alg(const char *name, u32 type, u32 mask)
{
int ret = 0;
struct crypto_alg *alg = crypto_alg_mod_lookup(name, type, mask);
if (!IS_ERR(alg)) {
crypto_mod_put(alg);
ret = 1;
}
return ret;
}
EXPORT_SYMBOL_GPL(crypto_has_alg);