diff --git a/include/linux/crc-t10dif.h b/include/linux/crc-t10dif.h index 1fe0cfcdea30..6bb0c0bf357b 100644 --- a/include/linux/crc-t10dif.h +++ b/include/linux/crc-t10dif.h @@ -6,6 +6,7 @@ #define CRC_T10DIF_DIGEST_SIZE 2 #define CRC_T10DIF_BLOCK_SIZE 1 +#define CRC_T10DIF_STRING "crct10dif" extern __u16 crc_t10dif_generic(__u16 crc, const unsigned char *buffer, size_t len); diff --git a/lib/crc-t10dif.c b/lib/crc-t10dif.c index 1ad33e555805..52f577a3868d 100644 --- a/lib/crc-t10dif.c +++ b/lib/crc-t10dif.c @@ -14,10 +14,47 @@ #include #include #include +#include #include +#include -static struct crypto_shash *crct10dif_tfm; +static struct crypto_shash __rcu *crct10dif_tfm; static struct static_key crct10dif_fallback __read_mostly; +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) { @@ -30,11 +67,14 @@ __u16 crc_t10dif_update(__u16 crc, const unsigned char *buffer, size_t len) if (static_key_false(&crct10dif_fallback)) return crc_t10dif_generic(crc, buffer, len); - desc.shash.tfm = crct10dif_tfm; + rcu_read_lock(); + desc.shash.tfm = rcu_dereference(crct10dif_tfm); desc.shash.flags = 0; *(__u16 *)desc.ctx = crc; err = crypto_shash_update(&desc.shash, buffer, len); + rcu_read_unlock(); + BUG_ON(err); return *(__u16 *)desc.ctx; @@ -49,6 +89,7 @@ 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); @@ -59,6 +100,7 @@ static int __init crc_t10dif_mod_init(void) static void __exit crc_t10dif_mod_fini(void) { + crypto_unregister_notifier(&crc_t10dif_nb); crypto_free_shash(crct10dif_tfm); }