43cd7f3861
commit af3ff8045bbf3e32f1a448542e73abb4c8ceb6f1 upstream.
Because the HMAC template didn't check that its underlying hash
algorithm is unkeyed, trying to use "hmac(hmac(sha3-512-generic))"
through AF_ALG or through KEYCTL_DH_COMPUTE resulted in the inner HMAC
being used without having been keyed, resulting in sha3_update() being
called without sha3_init(), causing a stack buffer overflow.
This is a very old bug, but it seems to have only started causing real
problems when SHA-3 support was added (requires CONFIG_CRYPTO_SHA3)
because the innermost hash's state is ->import()ed from a zeroed buffer,
and it just so happens that other hash algorithms are fine with that,
but SHA-3 is not. However, there could be arch or hardware-dependent
hash algorithms also affected; I couldn't test everything.
Fix the bug by introducing a function crypto_shash_alg_has_setkey()
which tests whether a shash algorithm is keyed. Then update the HMAC
template to require that its underlying hash algorithm is unkeyed.
Here is a reproducer:
#include <linux/if_alg.h>
#include <sys/socket.h>
int main()
{
int algfd;
struct sockaddr_alg addr = {
.salg_type = "hash",
.salg_name = "hmac(hmac(sha3-512-generic))",
};
char key[4096] = { 0 };
algfd = socket(AF_ALG, SOCK_SEQPACKET, 0);
bind(algfd, (const struct sockaddr *)&addr, sizeof(addr));
setsockopt(algfd, SOL_ALG, ALG_SET_KEY, key, sizeof(key));
}
Here was the KASAN report from syzbot:
BUG: KASAN: stack-out-of-bounds in memcpy include/linux/string.h:341 [inline]
BUG: KASAN: stack-out-of-bounds in sha3_update+0xdf/0x2e0 crypto/sha3_generic.c:161
Write of size 4096 at addr ffff8801cca07c40 by task syzkaller076574/3044
CPU: 1 PID: 3044 Comm: syzkaller076574 Not tainted 4.14.0-mm1+ #25
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x194/0x257 lib/dump_stack.c:53
print_address_description+0x73/0x250 mm/kasan/report.c:252
kasan_report_error mm/kasan/report.c:351 [inline]
kasan_report+0x25b/0x340 mm/kasan/report.c:409
check_memory_region_inline mm/kasan/kasan.c:260 [inline]
check_memory_region+0x137/0x190 mm/kasan/kasan.c:267
memcpy+0x37/0x50 mm/kasan/kasan.c:303
memcpy include/linux/string.h:341 [inline]
sha3_update+0xdf/0x2e0 crypto/sha3_generic.c:161
crypto_shash_update+0xcb/0x220 crypto/shash.c:109
shash_finup_unaligned+0x2a/0x60 crypto/shash.c:151
crypto_shash_finup+0xc4/0x120 crypto/shash.c:165
hmac_finup+0x182/0x330 crypto/hmac.c:152
crypto_shash_finup+0xc4/0x120 crypto/shash.c:165
shash_digest_unaligned+0x9e/0xd0 crypto/shash.c:172
crypto_shash_digest+0xc4/0x120 crypto/shash.c:186
hmac_setkey+0x36a/0x690 crypto/hmac.c:66
crypto_shash_setkey+0xad/0x190 crypto/shash.c:64
shash_async_setkey+0x47/0x60 crypto/shash.c:207
crypto_ahash_setkey+0xaf/0x180 crypto/ahash.c:200
hash_setkey+0x40/0x90 crypto/algif_hash.c:446
alg_setkey crypto/af_alg.c:221 [inline]
alg_setsockopt+0x2a1/0x350 crypto/af_alg.c:254
SYSC_setsockopt net/socket.c:1851 [inline]
SyS_setsockopt+0x189/0x360 net/socket.c:1830
entry_SYSCALL_64_fastpath+0x1f/0x96
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
265 lines
6.9 KiB
C
265 lines
6.9 KiB
C
/*
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* Hash algorithms.
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*
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* Copyright (c) 2008 Herbert Xu <herbert@gondor.apana.org.au>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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*/
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#ifndef _CRYPTO_INTERNAL_HASH_H
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#define _CRYPTO_INTERNAL_HASH_H
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#include <crypto/algapi.h>
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#include <crypto/hash.h>
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struct ahash_request;
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struct scatterlist;
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struct crypto_hash_walk {
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char *data;
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unsigned int offset;
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unsigned int alignmask;
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struct page *pg;
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unsigned int entrylen;
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unsigned int total;
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struct scatterlist *sg;
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unsigned int flags;
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};
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struct ahash_instance {
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struct ahash_alg alg;
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};
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struct shash_instance {
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struct shash_alg alg;
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};
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struct crypto_ahash_spawn {
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struct crypto_spawn base;
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};
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struct crypto_shash_spawn {
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struct crypto_spawn base;
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};
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extern const struct crypto_type crypto_ahash_type;
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int crypto_hash_walk_done(struct crypto_hash_walk *walk, int err);
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int crypto_hash_walk_first(struct ahash_request *req,
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struct crypto_hash_walk *walk);
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int crypto_ahash_walk_first(struct ahash_request *req,
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struct crypto_hash_walk *walk);
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int crypto_hash_walk_first_compat(struct hash_desc *hdesc,
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struct crypto_hash_walk *walk,
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struct scatterlist *sg, unsigned int len);
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static inline int crypto_ahash_walk_done(struct crypto_hash_walk *walk,
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int err)
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{
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return crypto_hash_walk_done(walk, err);
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}
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static inline int crypto_hash_walk_last(struct crypto_hash_walk *walk)
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{
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return !(walk->entrylen | walk->total);
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}
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static inline int crypto_ahash_walk_last(struct crypto_hash_walk *walk)
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{
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return crypto_hash_walk_last(walk);
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}
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int crypto_register_ahash(struct ahash_alg *alg);
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int crypto_unregister_ahash(struct ahash_alg *alg);
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int ahash_register_instance(struct crypto_template *tmpl,
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struct ahash_instance *inst);
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void ahash_free_instance(struct crypto_instance *inst);
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int shash_no_setkey(struct crypto_shash *tfm, const u8 *key,
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unsigned int keylen);
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static inline bool crypto_shash_alg_has_setkey(struct shash_alg *alg)
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{
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return alg->setkey != shash_no_setkey;
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}
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int crypto_init_ahash_spawn(struct crypto_ahash_spawn *spawn,
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struct hash_alg_common *alg,
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struct crypto_instance *inst);
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static inline void crypto_drop_ahash(struct crypto_ahash_spawn *spawn)
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{
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crypto_drop_spawn(&spawn->base);
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}
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struct hash_alg_common *ahash_attr_alg(struct rtattr *rta, u32 type, u32 mask);
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int crypto_register_shash(struct shash_alg *alg);
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int crypto_unregister_shash(struct shash_alg *alg);
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int crypto_register_shashes(struct shash_alg *algs, int count);
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int crypto_unregister_shashes(struct shash_alg *algs, int count);
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int shash_register_instance(struct crypto_template *tmpl,
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struct shash_instance *inst);
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void shash_free_instance(struct crypto_instance *inst);
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int crypto_init_shash_spawn(struct crypto_shash_spawn *spawn,
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struct shash_alg *alg,
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struct crypto_instance *inst);
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static inline void crypto_drop_shash(struct crypto_shash_spawn *spawn)
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{
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crypto_drop_spawn(&spawn->base);
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}
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struct shash_alg *shash_attr_alg(struct rtattr *rta, u32 type, u32 mask);
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int shash_ahash_update(struct ahash_request *req, struct shash_desc *desc);
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int shash_ahash_finup(struct ahash_request *req, struct shash_desc *desc);
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int shash_ahash_digest(struct ahash_request *req, struct shash_desc *desc);
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int shash_ahash_mcryptd_update(struct ahash_request *req,
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struct shash_desc *desc);
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int shash_ahash_mcryptd_final(struct ahash_request *req,
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struct shash_desc *desc);
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int shash_ahash_mcryptd_finup(struct ahash_request *req,
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struct shash_desc *desc);
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int shash_ahash_mcryptd_digest(struct ahash_request *req,
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struct shash_desc *desc);
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int crypto_init_shash_ops_async(struct crypto_tfm *tfm);
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static inline void *crypto_ahash_ctx(struct crypto_ahash *tfm)
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{
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return crypto_tfm_ctx(crypto_ahash_tfm(tfm));
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}
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static inline struct ahash_alg *__crypto_ahash_alg(struct crypto_alg *alg)
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{
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return container_of(__crypto_hash_alg_common(alg), struct ahash_alg,
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halg);
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}
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static inline void crypto_ahash_set_reqsize(struct crypto_ahash *tfm,
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unsigned int reqsize)
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{
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tfm->reqsize = reqsize;
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}
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static inline struct crypto_instance *ahash_crypto_instance(
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struct ahash_instance *inst)
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{
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return container_of(&inst->alg.halg.base, struct crypto_instance, alg);
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}
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static inline struct ahash_instance *ahash_instance(
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struct crypto_instance *inst)
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{
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return container_of(&inst->alg, struct ahash_instance, alg.halg.base);
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}
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static inline void *ahash_instance_ctx(struct ahash_instance *inst)
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{
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return crypto_instance_ctx(ahash_crypto_instance(inst));
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}
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static inline unsigned int ahash_instance_headroom(void)
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{
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return sizeof(struct ahash_alg) - sizeof(struct crypto_alg);
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}
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static inline struct ahash_instance *ahash_alloc_instance(
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const char *name, struct crypto_alg *alg)
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{
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return crypto_alloc_instance2(name, alg, ahash_instance_headroom());
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}
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static inline void ahash_request_complete(struct ahash_request *req, int err)
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{
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req->base.complete(&req->base, err);
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}
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static inline u32 ahash_request_flags(struct ahash_request *req)
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{
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return req->base.flags;
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}
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static inline struct crypto_ahash *crypto_spawn_ahash(
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struct crypto_ahash_spawn *spawn)
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{
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return crypto_spawn_tfm2(&spawn->base);
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}
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static inline int ahash_enqueue_request(struct crypto_queue *queue,
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struct ahash_request *request)
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{
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return crypto_enqueue_request(queue, &request->base);
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}
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static inline struct ahash_request *ahash_dequeue_request(
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struct crypto_queue *queue)
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{
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return ahash_request_cast(crypto_dequeue_request(queue));
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}
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static inline int ahash_tfm_in_queue(struct crypto_queue *queue,
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struct crypto_ahash *tfm)
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{
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return crypto_tfm_in_queue(queue, crypto_ahash_tfm(tfm));
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}
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static inline void *crypto_shash_ctx(struct crypto_shash *tfm)
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{
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return crypto_tfm_ctx(&tfm->base);
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}
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static inline struct crypto_instance *shash_crypto_instance(
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struct shash_instance *inst)
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{
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return container_of(&inst->alg.base, struct crypto_instance, alg);
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}
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static inline struct shash_instance *shash_instance(
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struct crypto_instance *inst)
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{
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return container_of(__crypto_shash_alg(&inst->alg),
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struct shash_instance, alg);
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}
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static inline void *shash_instance_ctx(struct shash_instance *inst)
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{
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return crypto_instance_ctx(shash_crypto_instance(inst));
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}
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static inline struct shash_instance *shash_alloc_instance(
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const char *name, struct crypto_alg *alg)
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{
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return crypto_alloc_instance2(name, alg,
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sizeof(struct shash_alg) - sizeof(*alg));
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}
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static inline struct crypto_shash *crypto_spawn_shash(
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struct crypto_shash_spawn *spawn)
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{
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return crypto_spawn_tfm2(&spawn->base);
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}
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static inline void *crypto_shash_ctx_aligned(struct crypto_shash *tfm)
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{
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return crypto_tfm_ctx_aligned(&tfm->base);
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}
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static inline struct crypto_shash *__crypto_shash_cast(struct crypto_tfm *tfm)
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{
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return container_of(tfm, struct crypto_shash, base);
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}
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#endif /* _CRYPTO_INTERNAL_HASH_H */
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