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>
123 lines
3 KiB
C
123 lines
3 KiB
C
/*
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* T10 Data Integrity Field CRC16 calculation
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*
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* Copyright (c) 2007 Oracle Corporation. All rights reserved.
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* Written by Martin K. Petersen <martin.petersen@oracle.com>
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*
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* This source code is licensed under the GNU General Public License,
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* Version 2. See the file COPYING for more details.
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*/
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#include <linux/types.h>
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#include <linux/module.h>
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#include <linux/crc-t10dif.h>
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#include <linux/err.h>
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#include <linux/init.h>
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#include <crypto/hash.h>
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#include <crypto/algapi.h>
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#include <linux/static_key.h>
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#include <linux/notifier.h>
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static struct crypto_shash __rcu *crct10dif_tfm;
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static struct static_key crct10dif_fallback __read_mostly;
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static DEFINE_MUTEX(crc_t10dif_mutex);
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static int crc_t10dif_rehash(struct notifier_block *self, unsigned long val, void *data)
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{
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struct crypto_alg *alg = data;
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struct crypto_shash *new, *old;
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if (val != CRYPTO_MSG_ALG_LOADED ||
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static_key_false(&crct10dif_fallback) ||
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strncmp(alg->cra_name, CRC_T10DIF_STRING, strlen(CRC_T10DIF_STRING)))
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return 0;
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mutex_lock(&crc_t10dif_mutex);
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old = rcu_dereference_protected(crct10dif_tfm,
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lockdep_is_held(&crc_t10dif_mutex));
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if (!old) {
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mutex_unlock(&crc_t10dif_mutex);
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return 0;
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}
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new = crypto_alloc_shash("crct10dif", 0, 0);
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if (IS_ERR(new)) {
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mutex_unlock(&crc_t10dif_mutex);
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return 0;
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}
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rcu_assign_pointer(crct10dif_tfm, new);
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mutex_unlock(&crc_t10dif_mutex);
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synchronize_rcu();
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crypto_free_shash(old);
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return 0;
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}
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static struct notifier_block crc_t10dif_nb = {
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.notifier_call = crc_t10dif_rehash,
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};
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__u16 crc_t10dif_update(__u16 crc, const unsigned char *buffer, size_t len)
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{
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struct {
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struct shash_desc shash;
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char ctx[2];
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} desc;
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int err;
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if (static_key_false(&crct10dif_fallback))
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return crc_t10dif_generic(crc, buffer, len);
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rcu_read_lock();
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desc.shash.tfm = rcu_dereference(crct10dif_tfm);
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*(__u16 *)desc.ctx = crc;
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err = crypto_shash_update(&desc.shash, buffer, len);
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rcu_read_unlock();
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BUG_ON(err);
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return *(__u16 *)desc.ctx;
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}
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EXPORT_SYMBOL(crc_t10dif_update);
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__u16 crc_t10dif(const unsigned char *buffer, size_t len)
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{
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return crc_t10dif_update(0, buffer, len);
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}
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EXPORT_SYMBOL(crc_t10dif);
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static int __init crc_t10dif_mod_init(void)
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{
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crypto_register_notifier(&crc_t10dif_nb);
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crct10dif_tfm = crypto_alloc_shash("crct10dif", 0, 0);
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if (IS_ERR(crct10dif_tfm)) {
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static_key_slow_inc(&crct10dif_fallback);
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crct10dif_tfm = NULL;
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}
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return 0;
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}
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static void __exit crc_t10dif_mod_fini(void)
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{
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crypto_unregister_notifier(&crc_t10dif_nb);
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crypto_free_shash(crct10dif_tfm);
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}
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module_init(crc_t10dif_mod_init);
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module_exit(crc_t10dif_mod_fini);
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static int crc_t10dif_transform_show(char *buffer, const struct kernel_param *kp)
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{
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if (static_key_false(&crct10dif_fallback))
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return sprintf(buffer, "fallback\n");
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return sprintf(buffer, "%s\n",
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crypto_tfm_alg_driver_name(crypto_shash_tfm(crct10dif_tfm)));
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}
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module_param_call(transform, NULL, crc_t10dif_transform_show, NULL, 0644);
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MODULE_DESCRIPTION("T10 DIF CRC calculation");
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MODULE_LICENSE("GPL");
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MODULE_SOFTDEP("pre: crct10dif");
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