linux/include/crypto/algapi.h

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/*
* Cryptographic API for algorithms (i.e., low-level API).
*
* Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
*
* 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.
*
*/
#ifndef _CRYPTO_ALGAPI_H
#define _CRYPTO_ALGAPI_H
#include <linux/crypto.h>
#include <linux/list.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
struct crypto_aead;
struct crypto_instance;
struct module;
struct rtattr;
struct seq_file;
struct crypto_type {
unsigned int (*ctxsize)(struct crypto_alg *alg, u32 type, u32 mask);
unsigned int (*extsize)(struct crypto_alg *alg);
int (*init)(struct crypto_tfm *tfm, u32 type, u32 mask);
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);
struct crypto_alg *(*lookup)(const char *name, u32 type, u32 mask);
void (*free)(struct crypto_instance *inst);
unsigned int type;
unsigned int maskclear;
unsigned int maskset;
unsigned int tfmsize;
};
struct crypto_instance {
struct crypto_alg alg;
struct crypto_template *tmpl;
struct hlist_node list;
void *__ctx[] CRYPTO_MINALIGN_ATTR;
};
struct crypto_template {
struct list_head list;
struct hlist_head instances;
struct module *module;
struct crypto_instance *(*alloc)(struct rtattr **tb);
void (*free)(struct crypto_instance *inst);
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;
struct crypto_instance *inst;
const struct crypto_type *frontend;
u32 mask;
};
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 blkcipher_walk {
union {
struct {
struct page *page;
unsigned long offset;
} phys;
struct {
u8 *page;
u8 *addr;
} virt;
} src, dst;
struct scatter_walk in;
unsigned int nbytes;
struct scatter_walk out;
unsigned int total;
void *page;
u8 *buffer;
u8 *iv;
unsigned int ivsize;
int flags;
unsigned int walk_blocksize;
unsigned int cipher_blocksize;
unsigned int alignmask;
};
struct ablkcipher_walk {
struct {
struct page *page;
unsigned int offset;
} src, dst;
struct scatter_walk in;
unsigned int nbytes;
struct scatter_walk out;
unsigned int total;
struct list_head buffers;
u8 *iv_buffer;
u8 *iv;
int flags;
unsigned int blocksize;
};
extern const struct crypto_type crypto_ablkcipher_type;
extern const struct crypto_type crypto_blkcipher_type;
void crypto_mod_put(struct crypto_alg *alg);
int crypto_register_template(struct crypto_template *tmpl);
void crypto_unregister_template(struct crypto_template *tmpl);
struct crypto_template *crypto_lookup_template(const char *name);
int crypto_register_instance(struct crypto_template *tmpl,
struct crypto_instance *inst);
int crypto_unregister_instance(struct crypto_instance *inst);
int crypto_init_spawn(struct crypto_spawn *spawn, struct crypto_alg *alg,
struct crypto_instance *inst, u32 mask);
int crypto_init_spawn2(struct crypto_spawn *spawn, struct crypto_alg *alg,
struct crypto_instance *inst,
const struct crypto_type *frontend);
int crypto_grab_spawn(struct crypto_spawn *spawn, 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);
static inline void crypto_set_spawn(struct crypto_spawn *spawn,
struct crypto_instance *inst)
{
spawn->inst = inst;
}
struct crypto_attr_type *crypto_get_attr_type(struct rtattr **tb);
int crypto_check_attr_type(struct rtattr **tb, u32 type);
const char *crypto_attr_alg_name(struct rtattr *rta);
struct crypto_alg *crypto_attr_alg2(struct rtattr *rta,
const struct crypto_type *frontend,
u32 type, u32 mask);
static inline struct crypto_alg *crypto_attr_alg(struct rtattr *rta,
u32 type, u32 mask)
{
return crypto_attr_alg2(rta, NULL, type, mask);
}
int crypto_attr_u32(struct rtattr *rta, u32 *num);
void *crypto_alloc_instance2(const char *name, struct crypto_alg *alg,
unsigned int head);
struct crypto_instance *crypto_alloc_instance(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);
struct crypto_async_request *crypto_dequeue_request(struct crypto_queue *queue);
int crypto_tfm_in_queue(struct crypto_queue *queue, struct crypto_tfm *tfm);
static inline unsigned int crypto_queue_len(struct crypto_queue *queue)
{
return queue->qlen;
}
/* These functions require the input/output to be aligned as u32. */
void crypto_inc(u8 *a, unsigned int size);
void crypto_xor(u8 *dst, const u8 *src, unsigned int size);
int blkcipher_walk_done(struct blkcipher_desc *desc,
struct blkcipher_walk *walk, int err);
int blkcipher_walk_virt(struct blkcipher_desc *desc,
struct blkcipher_walk *walk);
int blkcipher_walk_phys(struct blkcipher_desc *desc,
struct blkcipher_walk *walk);
int blkcipher_walk_virt_block(struct blkcipher_desc *desc,
struct blkcipher_walk *walk,
unsigned int blocksize);
int blkcipher_aead_walk_virt_block(struct blkcipher_desc *desc,
struct blkcipher_walk *walk,
struct crypto_aead *tfm,
unsigned int blocksize);
int ablkcipher_walk_done(struct ablkcipher_request *req,
struct ablkcipher_walk *walk, int err);
int ablkcipher_walk_phys(struct ablkcipher_request *req,
struct ablkcipher_walk *walk);
void __ablkcipher_walk_complete(struct ablkcipher_walk *walk);
static inline void *crypto_tfm_ctx_aligned(struct crypto_tfm *tfm)
{
return PTR_ALIGN(crypto_tfm_ctx(tfm),
crypto_tfm_alg_alignmask(tfm) + 1);
}
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 ablkcipher_alg *crypto_ablkcipher_alg(
struct crypto_ablkcipher *tfm)
{
return &crypto_ablkcipher_tfm(tfm)->__crt_alg->cra_ablkcipher;
}
static inline void *crypto_ablkcipher_ctx(struct crypto_ablkcipher *tfm)
{
return crypto_tfm_ctx(&tfm->base);
}
static inline void *crypto_ablkcipher_ctx_aligned(struct crypto_ablkcipher *tfm)
{
return crypto_tfm_ctx_aligned(&tfm->base);
}
static inline struct crypto_blkcipher *crypto_spawn_blkcipher(
struct crypto_spawn *spawn)
{
u32 type = CRYPTO_ALG_TYPE_BLKCIPHER;
u32 mask = CRYPTO_ALG_TYPE_MASK;
return __crypto_blkcipher_cast(crypto_spawn_tfm(spawn, type, mask));
}
static inline void *crypto_blkcipher_ctx(struct crypto_blkcipher *tfm)
{
return crypto_tfm_ctx(&tfm->base);
}
static inline void *crypto_blkcipher_ctx_aligned(struct crypto_blkcipher *tfm)
{
return crypto_tfm_ctx_aligned(&tfm->base);
}
static inline struct crypto_cipher *crypto_spawn_cipher(
struct crypto_spawn *spawn)
{
u32 type = CRYPTO_ALG_TYPE_CIPHER;
u32 mask = CRYPTO_ALG_TYPE_MASK;
return __crypto_cipher_cast(crypto_spawn_tfm(spawn, type, mask));
}
static inline struct cipher_alg *crypto_cipher_alg(struct crypto_cipher *tfm)
{
return &crypto_cipher_tfm(tfm)->__crt_alg->cra_cipher;
}
static inline struct crypto_hash *crypto_spawn_hash(struct crypto_spawn *spawn)
{
u32 type = CRYPTO_ALG_TYPE_HASH;
u32 mask = CRYPTO_ALG_TYPE_HASH_MASK;
return __crypto_hash_cast(crypto_spawn_tfm(spawn, type, mask));
}
static inline void *crypto_hash_ctx(struct crypto_hash *tfm)
{
return crypto_tfm_ctx(&tfm->base);
}
static inline void *crypto_hash_ctx_aligned(struct crypto_hash *tfm)
{
return crypto_tfm_ctx_aligned(&tfm->base);
}
static inline void blkcipher_walk_init(struct blkcipher_walk *walk,
struct scatterlist *dst,
struct scatterlist *src,
unsigned int nbytes)
{
walk->in.sg = src;
walk->out.sg = dst;
walk->total = nbytes;
}
static inline void ablkcipher_walk_init(struct ablkcipher_walk *walk,
struct scatterlist *dst,
struct scatterlist *src,
unsigned int nbytes)
{
walk->in.sg = src;
walk->out.sg = dst;
walk->total = nbytes;
INIT_LIST_HEAD(&walk->buffers);
}
static inline void ablkcipher_walk_complete(struct ablkcipher_walk *walk)
{
if (unlikely(!list_empty(&walk->buffers)))
__ablkcipher_walk_complete(walk);
}
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 int ablkcipher_enqueue_request(struct crypto_queue *queue,
struct ablkcipher_request *request)
{
return crypto_enqueue_request(queue, &request->base);
}
static inline struct ablkcipher_request *ablkcipher_dequeue_request(
struct crypto_queue *queue)
{
return ablkcipher_request_cast(crypto_dequeue_request(queue));
}
static inline void *ablkcipher_request_ctx(struct ablkcipher_request *req)
{
return req->__ctx;
}
static inline int ablkcipher_tfm_in_queue(struct crypto_queue *queue,
struct crypto_ablkcipher *tfm)
{
return crypto_tfm_in_queue(queue, crypto_ablkcipher_tfm(tfm));
}
static inline struct crypto_alg *crypto_get_attr_alg(struct rtattr **tb,
u32 type, u32 mask)
{
return crypto_attr_alg(tb[1], type, mask);
}
/*
* Returns CRYPTO_ALG_ASYNC if type/mask requires the use of sync algorithms.
* Otherwise returns zero.
*/
static inline int crypto_requires_sync(u32 type, u32 mask)
{
return (type ^ CRYPTO_ALG_ASYNC) & mask & CRYPTO_ALG_ASYNC;
}
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 16:20:39 +08:00
noinline unsigned long __crypto_memneq(const void *a, const void *b, size_t size);
/**
* crypto_memneq - Compare two areas of memory without leaking
* timing information.
*
* @a: One area of memory
* @b: Another area of memory
* @size: The size of the area.
*
* Returns 0 when data is equal, 1 otherwise.
*/
static inline int crypto_memneq(const void *a, const void *b, size_t size)
{
return __crypto_memneq(a, b, size) != 0UL ? 1 : 0;
}
static inline void crypto_yield(u32 flags)
{
if (flags & CRYPTO_TFM_REQ_MAY_SLEEP)
cond_resched();
}
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 16:20:39 +08:00
#endif /* _CRYPTO_ALGAPI_H */