mirror of
https://github.com/torvalds/linux
synced 2024-11-05 18:23:50 +00:00
877b5691f2
The flags field in 'struct shash_desc' never actually does anything. The only ostensibly supported flag is CRYPTO_TFM_REQ_MAY_SLEEP. However, no shash algorithm ever sleeps, making this flag a no-op. With this being the case, inevitably some users who can't sleep wrongly pass MAY_SLEEP. These would all need to be fixed if any shash algorithm actually started sleeping. For example, the shash_ahash_*() functions, which wrap a shash algorithm with the ahash API, pass through MAY_SLEEP from the ahash API to the shash API. However, the shash functions are called under kmap_atomic(), so actually they're assumed to never sleep. Even if it turns out that some users do need preemption points while hashing large buffers, we could easily provide a helper function crypto_shash_update_large() which divides the data into smaller chunks and calls crypto_shash_update() and cond_resched() for each chunk. It's not necessary to have a flag in 'struct shash_desc', nor is it necessary to make individual shash algorithms aware of this at all. Therefore, remove shash_desc::flags, and document that the crypto_shash_*() functions can be called from any context. Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
122 lines
3 KiB
C
122 lines
3 KiB
C
/*
|
|
* T10 Data Integrity Field CRC16 calculation
|
|
*
|
|
* Copyright (c) 2007 Oracle Corporation. All rights reserved.
|
|
* Written by Martin K. Petersen <martin.petersen@oracle.com>
|
|
*
|
|
* This source code is licensed under the GNU General Public License,
|
|
* Version 2. See the file COPYING for more details.
|
|
*/
|
|
|
|
#include <linux/types.h>
|
|
#include <linux/module.h>
|
|
#include <linux/crc-t10dif.h>
|
|
#include <linux/err.h>
|
|
#include <linux/init.h>
|
|
#include <crypto/hash.h>
|
|
#include <crypto/algapi.h>
|
|
#include <linux/static_key.h>
|
|
#include <linux/notifier.h>
|
|
|
|
static struct crypto_shash __rcu *crct10dif_tfm;
|
|
static struct static_key crct10dif_fallback __read_mostly;
|
|
static DEFINE_MUTEX(crc_t10dif_mutex);
|
|
|
|
static int crc_t10dif_rehash(struct notifier_block *self, unsigned long val, void *data)
|
|
{
|
|
struct crypto_alg *alg = data;
|
|
struct crypto_shash *new, *old;
|
|
|
|
if (val != CRYPTO_MSG_ALG_LOADED ||
|
|
static_key_false(&crct10dif_fallback) ||
|
|
strncmp(alg->cra_name, CRC_T10DIF_STRING, strlen(CRC_T10DIF_STRING)))
|
|
return 0;
|
|
|
|
mutex_lock(&crc_t10dif_mutex);
|
|
old = rcu_dereference_protected(crct10dif_tfm,
|
|
lockdep_is_held(&crc_t10dif_mutex));
|
|
if (!old) {
|
|
mutex_unlock(&crc_t10dif_mutex);
|
|
return 0;
|
|
}
|
|
new = crypto_alloc_shash("crct10dif", 0, 0);
|
|
if (IS_ERR(new)) {
|
|
mutex_unlock(&crc_t10dif_mutex);
|
|
return 0;
|
|
}
|
|
rcu_assign_pointer(crct10dif_tfm, new);
|
|
mutex_unlock(&crc_t10dif_mutex);
|
|
|
|
synchronize_rcu();
|
|
crypto_free_shash(old);
|
|
return 0;
|
|
}
|
|
|
|
static struct notifier_block crc_t10dif_nb = {
|
|
.notifier_call = crc_t10dif_rehash,
|
|
};
|
|
|
|
__u16 crc_t10dif_update(__u16 crc, const unsigned char *buffer, size_t len)
|
|
{
|
|
struct {
|
|
struct shash_desc shash;
|
|
char ctx[2];
|
|
} desc;
|
|
int err;
|
|
|
|
if (static_key_false(&crct10dif_fallback))
|
|
return crc_t10dif_generic(crc, buffer, len);
|
|
|
|
rcu_read_lock();
|
|
desc.shash.tfm = rcu_dereference(crct10dif_tfm);
|
|
*(__u16 *)desc.ctx = crc;
|
|
|
|
err = crypto_shash_update(&desc.shash, buffer, len);
|
|
rcu_read_unlock();
|
|
|
|
BUG_ON(err);
|
|
|
|
return *(__u16 *)desc.ctx;
|
|
}
|
|
EXPORT_SYMBOL(crc_t10dif_update);
|
|
|
|
__u16 crc_t10dif(const unsigned char *buffer, size_t len)
|
|
{
|
|
return crc_t10dif_update(0, buffer, len);
|
|
}
|
|
EXPORT_SYMBOL(crc_t10dif);
|
|
|
|
static int __init crc_t10dif_mod_init(void)
|
|
{
|
|
crypto_register_notifier(&crc_t10dif_nb);
|
|
crct10dif_tfm = crypto_alloc_shash("crct10dif", 0, 0);
|
|
if (IS_ERR(crct10dif_tfm)) {
|
|
static_key_slow_inc(&crct10dif_fallback);
|
|
crct10dif_tfm = NULL;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static void __exit crc_t10dif_mod_fini(void)
|
|
{
|
|
crypto_unregister_notifier(&crc_t10dif_nb);
|
|
crypto_free_shash(crct10dif_tfm);
|
|
}
|
|
|
|
module_init(crc_t10dif_mod_init);
|
|
module_exit(crc_t10dif_mod_fini);
|
|
|
|
static int crc_t10dif_transform_show(char *buffer, const struct kernel_param *kp)
|
|
{
|
|
if (static_key_false(&crct10dif_fallback))
|
|
return sprintf(buffer, "fallback\n");
|
|
|
|
return sprintf(buffer, "%s\n",
|
|
crypto_tfm_alg_driver_name(crypto_shash_tfm(crct10dif_tfm)));
|
|
}
|
|
|
|
module_param_call(transform, NULL, crc_t10dif_transform_show, NULL, 0644);
|
|
|
|
MODULE_DESCRIPTION("T10 DIF CRC calculation");
|
|
MODULE_LICENSE("GPL");
|
|
MODULE_SOFTDEP("pre: crct10dif");
|