linux-stable/include/crypto/algapi.h

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/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* Cryptographic API for algorithms (i.e., low-level API).
*
* Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
*/
#ifndef _CRYPTO_ALGAPI_H
#define _CRYPTO_ALGAPI_H
#include <crypto/utils.h>
#include <linux/align.h>
#include <linux/cache.h>
#include <linux/crypto.h>
#include <linux/types.h>
#include <linux/workqueue.h>
/*
* Maximum values for blocksize and alignmask, used to allocate
* static buffers that are big enough for any combination of
* algs and architectures. Ciphers have a lower maximum size.
*/
#define MAX_ALGAPI_BLOCKSIZE 160
#define MAX_ALGAPI_ALIGNMASK 127
#define MAX_CIPHER_BLOCKSIZE 16
#define MAX_CIPHER_ALIGNMASK 15
#ifdef ARCH_DMA_MINALIGN
#define CRYPTO_DMA_ALIGN ARCH_DMA_MINALIGN
#else
#define CRYPTO_DMA_ALIGN CRYPTO_MINALIGN
#endif
#define CRYPTO_DMA_PADDING ((CRYPTO_DMA_ALIGN - 1) & ~(CRYPTO_MINALIGN - 1))
/*
* Autoloaded crypto modules should only use a prefixed name to avoid allowing
* arbitrary modules to be loaded. Loading from userspace may still need the
* unprefixed names, so retains those aliases as well.
* This uses __MODULE_INFO directly instead of MODULE_ALIAS because pre-4.3
* gcc (e.g. avr32 toolchain) uses __LINE__ for uniqueness, and this macro
* expands twice on the same line. Instead, use a separate base name for the
* alias.
*/
#define MODULE_ALIAS_CRYPTO(name) \
__MODULE_INFO(alias, alias_userspace, name); \
__MODULE_INFO(alias, alias_crypto, "crypto-" name)
struct crypto_aead;
struct crypto_instance;
struct module;
struct notifier_block;
struct rtattr;
struct scatterlist;
struct seq_file;
struct sk_buff;
struct crypto_type {
unsigned int (*ctxsize)(struct crypto_alg *alg, u32 type, u32 mask);
unsigned int (*extsize)(struct crypto_alg *alg);
int (*init_tfm)(struct crypto_tfm *tfm);
void (*show)(struct seq_file *m, struct crypto_alg *alg);
int (*report)(struct sk_buff *skb, struct crypto_alg *alg);
void (*free)(struct crypto_instance *inst);
#ifdef CONFIG_CRYPTO_STATS
int (*report_stat)(struct sk_buff *skb, struct crypto_alg *alg);
#endif
unsigned int type;
unsigned int maskclear;
unsigned int maskset;
unsigned int tfmsize;
};
struct crypto_instance {
struct crypto_alg alg;
struct crypto_template *tmpl;
union {
/* Node in list of instances after registration. */
struct hlist_node list;
/* List of attached spawns before registration. */
struct crypto_spawn *spawns;
};
struct work_struct free_work;
void *__ctx[] CRYPTO_MINALIGN_ATTR;
};
struct crypto_template {
struct list_head list;
struct hlist_head instances;
struct module *module;
int (*create)(struct crypto_template *tmpl, struct rtattr **tb);
char name[CRYPTO_MAX_ALG_NAME];
};
struct crypto_spawn {
struct list_head list;
struct crypto_alg *alg;
union {
/* Back pointer to instance after registration.*/
struct crypto_instance *inst;
/* Spawn list pointer prior to registration. */
struct crypto_spawn *next;
};
const struct crypto_type *frontend;
u32 mask;
bool dead;
bool registered;
};
struct crypto_queue {
struct list_head list;
struct list_head *backlog;
unsigned int qlen;
unsigned int max_qlen;
};
struct scatter_walk {
struct scatterlist *sg;
unsigned int offset;
};
struct crypto_attr_alg {
char name[CRYPTO_MAX_ALG_NAME];
};
struct crypto_attr_type {
u32 type;
u32 mask;
};
/*
* Algorithm registration interface.
*/
int crypto_register_alg(struct crypto_alg *alg);
void crypto_unregister_alg(struct crypto_alg *alg);
int crypto_register_algs(struct crypto_alg *algs, int count);
void crypto_unregister_algs(struct crypto_alg *algs, int count);
void crypto_mod_put(struct crypto_alg *alg);
int crypto_register_template(struct crypto_template *tmpl);
int crypto_register_templates(struct crypto_template *tmpls, int count);
void crypto_unregister_template(struct crypto_template *tmpl);
void crypto_unregister_templates(struct crypto_template *tmpls, int count);
struct crypto_template *crypto_lookup_template(const char *name);
int crypto_register_instance(struct crypto_template *tmpl,
struct crypto_instance *inst);
void crypto_unregister_instance(struct crypto_instance *inst);
int crypto_grab_spawn(struct crypto_spawn *spawn, struct crypto_instance *inst,
const char *name, u32 type, u32 mask);
void crypto_drop_spawn(struct crypto_spawn *spawn);
struct crypto_tfm *crypto_spawn_tfm(struct crypto_spawn *spawn, u32 type,
u32 mask);
void *crypto_spawn_tfm2(struct crypto_spawn *spawn);
struct crypto_attr_type *crypto_get_attr_type(struct rtattr **tb);
int crypto_check_attr_type(struct rtattr **tb, u32 type, u32 *mask_ret);
const char *crypto_attr_alg_name(struct rtattr *rta);
int crypto_inst_setname(struct crypto_instance *inst, const char *name,
struct crypto_alg *alg);
void crypto_init_queue(struct crypto_queue *queue, unsigned int max_qlen);
int crypto_enqueue_request(struct crypto_queue *queue,
struct crypto_async_request *request);
void crypto_enqueue_request_head(struct crypto_queue *queue,
struct crypto_async_request *request);
struct crypto_async_request *crypto_dequeue_request(struct crypto_queue *queue);
static inline unsigned int crypto_queue_len(struct crypto_queue *queue)
{
return queue->qlen;
}
void crypto_inc(u8 *a, unsigned int size);
static inline void *crypto_tfm_ctx(struct crypto_tfm *tfm)
{
return tfm->__crt_ctx;
}
static inline void *crypto_tfm_ctx_align(struct crypto_tfm *tfm,
unsigned int align)
{
if (align <= crypto_tfm_ctx_alignment())
align = 1;
return PTR_ALIGN(crypto_tfm_ctx(tfm), align);
}
static inline unsigned int crypto_dma_align(void)
{
return CRYPTO_DMA_ALIGN;
}
static inline unsigned int crypto_dma_padding(void)
{
return (crypto_dma_align() - 1) & ~(crypto_tfm_ctx_alignment() - 1);
}
static inline void *crypto_tfm_ctx_dma(struct crypto_tfm *tfm)
{
return crypto_tfm_ctx_align(tfm, crypto_dma_align());
}
static inline struct crypto_instance *crypto_tfm_alg_instance(
struct crypto_tfm *tfm)
{
return container_of(tfm->__crt_alg, struct crypto_instance, alg);
}
static inline void *crypto_instance_ctx(struct crypto_instance *inst)
{
return inst->__ctx;
}
static inline struct crypto_async_request *crypto_get_backlog(
struct crypto_queue *queue)
{
return queue->backlog == &queue->list ? NULL :
container_of(queue->backlog, struct crypto_async_request, list);
}
static inline u32 crypto_requires_off(struct crypto_attr_type *algt, u32 off)
{
return (algt->type ^ off) & algt->mask & off;
}
/*
* When an algorithm uses another algorithm (e.g., if it's an instance of a
* template), these are the flags that should always be set on the "outer"
* algorithm if any "inner" algorithm has them set.
*/
#define CRYPTO_ALG_INHERITED_FLAGS \
(CRYPTO_ALG_ASYNC | CRYPTO_ALG_NEED_FALLBACK | \
CRYPTO_ALG_ALLOCATES_MEMORY)
/*
* Given the type and mask that specify the flags restrictions on a template
* instance being created, return the mask that should be passed to
* crypto_grab_*() (along with type=0) to honor any request the user made to
* have any of the CRYPTO_ALG_INHERITED_FLAGS clear.
*/
static inline u32 crypto_algt_inherited_mask(struct crypto_attr_type *algt)
{
return crypto_requires_off(algt, CRYPTO_ALG_INHERITED_FLAGS);
}
int crypto_register_notifier(struct notifier_block *nb);
int crypto_unregister_notifier(struct notifier_block *nb);
/* Crypto notification events. */
enum {
CRYPTO_MSG_ALG_REQUEST,
CRYPTO_MSG_ALG_REGISTER,
CRYPTO_MSG_ALG_LOADED,
};
static inline void crypto_request_complete(struct crypto_async_request *req,
int err)
{
req->complete(req->data, err);
}
static inline u32 crypto_tfm_alg_type(struct crypto_tfm *tfm)
{
return tfm->__crt_alg->cra_flags & CRYPTO_ALG_TYPE_MASK;
}
crypto: crypto_memneq - add equality testing of memory regions w/o timing leaks When comparing MAC hashes, AEAD authentication tags, or other hash values in the context of authentication or integrity checking, it is important not to leak timing information to a potential attacker, i.e. when communication happens over a network. Bytewise memory comparisons (such as memcmp) are usually optimized so that they return a nonzero value as soon as a mismatch is found. E.g, on x86_64/i5 for 512 bytes this can be ~50 cyc for a full mismatch and up to ~850 cyc for a full match (cold). This early-return behavior can leak timing information as a side channel, allowing an attacker to iteratively guess the correct result. This patch adds a new method crypto_memneq ("memory not equal to each other") to the crypto API that compares memory areas of the same length in roughly "constant time" (cache misses could change the timing, but since they don't reveal information about the content of the strings being compared, they are effectively benign). Iow, best and worst case behaviour take the same amount of time to complete (in contrast to memcmp). Note that crypto_memneq (unlike memcmp) can only be used to test for equality or inequality, NOT for lexicographical order. This, however, is not an issue for its use-cases within the crypto API. We tried to locate all of the places in the crypto API where memcmp was being used for authentication or integrity checking, and convert them over to crypto_memneq. crypto_memneq is declared noinline, placed in its own source file, and compiled with optimizations that might increase code size disabled ("Os") because a smart compiler (or LTO) might notice that the return value is always compared against zero/nonzero, and might then reintroduce the same early-return optimization that we are trying to avoid. Using #pragma or __attribute__ optimization annotations of the code for disabling optimization was avoided as it seems to be considered broken or unmaintained for long time in GCC [1]. Therefore, we work around that by specifying the compile flag for memneq.o directly in the Makefile. We found that this seems to be most appropriate. As we use ("Os"), this patch also provides a loop-free "fast-path" for frequently used 16 byte digests. Similarly to kernel library string functions, leave an option for future even further optimized architecture specific assembler implementations. This was a joint work of James Yonan and Daniel Borkmann. Also thanks for feedback from Florian Weimer on this and earlier proposals [2]. [1] http://gcc.gnu.org/ml/gcc/2012-07/msg00211.html [2] https://lkml.org/lkml/2013/2/10/131 Signed-off-by: James Yonan <james@openvpn.net> Signed-off-by: Daniel Borkmann <dborkman@redhat.com> Cc: Florian Weimer <fw@deneb.enyo.de> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2013-09-26 08:20:39 +00:00
#endif /* _CRYPTO_ALGAPI_H */