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linux/crypto/hmac.c
Eric Biggers 7bcb2c99f8 crypto: algapi - use common mechanism for inheriting flags 
The flag CRYPTO_ALG_ASYNC is "inherited" in the sense that when a
template is instantiated, the template will have CRYPTO_ALG_ASYNC set if
any of the algorithms it uses has CRYPTO_ALG_ASYNC set.

We'd like to add a second flag (CRYPTO_ALG_ALLOCATES_MEMORY) that gets
"inherited" in the same way.  This is difficult because the handling of
CRYPTO_ALG_ASYNC is hardcoded everywhere.  Address this by:

  - Add CRYPTO_ALG_INHERITED_FLAGS, which contains the set of flags that
    have these inheritance semantics.

  - Add crypto_algt_inherited_mask(), for use by template ->create()
    methods.  It returns any of these flags that the user asked to be
    unset and thus must be passed in the 'mask' to crypto_grab_*().

  - Also modify crypto_check_attr_type() to handle computing the 'mask'
    so that most templates can just use this.

  - Make crypto_grab_*() propagate these flags to the template instance
    being created so that templates don't have to do this themselves.

Make crypto/simd.c propagate these flags too, since it "wraps" another
algorithm, similar to a template.

Based on a patch by Mikulas Patocka <mpatocka@redhat.com>
(https://lore.kernel.org/r/alpine.LRH.2.02.2006301414580.30526@file01.intranet.prod.int.rdu2.redhat.com).

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2020-07-16 21:49:08 +10:00

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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Cryptographic API.
*
* HMAC: Keyed-Hashing for Message Authentication (RFC2104).
*
* Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
* Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
*
* The HMAC implementation is derived from USAGI.
* Copyright (c) 2002 Kazunori Miyazawa <miyazawa@linux-ipv6.org> / USAGI
*/
#include <crypto/hmac.h>
#include <crypto/internal/hash.h>
#include <crypto/scatterwalk.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/scatterlist.h>
#include <linux/string.h>
struct hmac_ctx {
struct crypto_shash *hash;
};
static inline void *align_ptr(void *p, unsigned int align)
{
return (void *)ALIGN((unsigned long)p, align);
}
static inline struct hmac_ctx *hmac_ctx(struct crypto_shash *tfm)
{
return align_ptr(crypto_shash_ctx_aligned(tfm) +
crypto_shash_statesize(tfm) * 2,
crypto_tfm_ctx_alignment());
}
static int hmac_setkey(struct crypto_shash *parent,
const u8 *inkey, unsigned int keylen)
{
int bs = crypto_shash_blocksize(parent);
int ds = crypto_shash_digestsize(parent);
int ss = crypto_shash_statesize(parent);
char *ipad = crypto_shash_ctx_aligned(parent);
char *opad = ipad + ss;
struct hmac_ctx *ctx = align_ptr(opad + ss,
crypto_tfm_ctx_alignment());
struct crypto_shash *hash = ctx->hash;
SHASH_DESC_ON_STACK(shash, hash);
unsigned int i;
shash->tfm = hash;
if (keylen > bs) {
int err;
err = crypto_shash_digest(shash, inkey, keylen, ipad);
if (err)
return err;
keylen = ds;
} else
memcpy(ipad, inkey, keylen);
memset(ipad + keylen, 0, bs - keylen);
memcpy(opad, ipad, bs);
for (i = 0; i < bs; i++) {
ipad[i] ^= HMAC_IPAD_VALUE;
opad[i] ^= HMAC_OPAD_VALUE;
}
return crypto_shash_init(shash) ?:
crypto_shash_update(shash, ipad, bs) ?:
crypto_shash_export(shash, ipad) ?:
crypto_shash_init(shash) ?:
crypto_shash_update(shash, opad, bs) ?:
crypto_shash_export(shash, opad);
}
static int hmac_export(struct shash_desc *pdesc, void *out)
{
struct shash_desc *desc = shash_desc_ctx(pdesc);
return crypto_shash_export(desc, out);
}
static int hmac_import(struct shash_desc *pdesc, const void *in)
{
struct shash_desc *desc = shash_desc_ctx(pdesc);
struct hmac_ctx *ctx = hmac_ctx(pdesc->tfm);
desc->tfm = ctx->hash;
return crypto_shash_import(desc, in);
}
static int hmac_init(struct shash_desc *pdesc)
{
return hmac_import(pdesc, crypto_shash_ctx_aligned(pdesc->tfm));
}
static int hmac_update(struct shash_desc *pdesc,
const u8 *data, unsigned int nbytes)
{
struct shash_desc *desc = shash_desc_ctx(pdesc);
return crypto_shash_update(desc, data, nbytes);
}
static int hmac_final(struct shash_desc *pdesc, u8 *out)
{
struct crypto_shash *parent = pdesc->tfm;
int ds = crypto_shash_digestsize(parent);
int ss = crypto_shash_statesize(parent);
char *opad = crypto_shash_ctx_aligned(parent) + ss;
struct shash_desc *desc = shash_desc_ctx(pdesc);
return crypto_shash_final(desc, out) ?:
crypto_shash_import(desc, opad) ?:
crypto_shash_finup(desc, out, ds, out);
}
static int hmac_finup(struct shash_desc *pdesc, const u8 *data,
unsigned int nbytes, u8 *out)
{
struct crypto_shash *parent = pdesc->tfm;
int ds = crypto_shash_digestsize(parent);
int ss = crypto_shash_statesize(parent);
char *opad = crypto_shash_ctx_aligned(parent) + ss;
struct shash_desc *desc = shash_desc_ctx(pdesc);
return crypto_shash_finup(desc, data, nbytes, out) ?:
crypto_shash_import(desc, opad) ?:
crypto_shash_finup(desc, out, ds, out);
}
static int hmac_init_tfm(struct crypto_shash *parent)
{
struct crypto_shash *hash;
struct shash_instance *inst = shash_alg_instance(parent);
struct crypto_shash_spawn *spawn = shash_instance_ctx(inst);
struct hmac_ctx *ctx = hmac_ctx(parent);
hash = crypto_spawn_shash(spawn);
if (IS_ERR(hash))
return PTR_ERR(hash);
parent->descsize = sizeof(struct shash_desc) +
crypto_shash_descsize(hash);
ctx->hash = hash;
return 0;
}
static void hmac_exit_tfm(struct crypto_shash *parent)
{
struct hmac_ctx *ctx = hmac_ctx(parent);
crypto_free_shash(ctx->hash);
}
static int hmac_create(struct crypto_template *tmpl, struct rtattr **tb)
{
struct shash_instance *inst;
struct crypto_shash_spawn *spawn;
struct crypto_alg *alg;
struct shash_alg *salg;
u32 mask;
int err;
int ds;
int ss;
err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH, &mask);
if (err)
return err;
inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
if (!inst)
return -ENOMEM;
spawn = shash_instance_ctx(inst);
err = crypto_grab_shash(spawn, shash_crypto_instance(inst),
crypto_attr_alg_name(tb[1]), 0, mask);
if (err)
goto err_free_inst;
salg = crypto_spawn_shash_alg(spawn);
alg = &salg->base;
/* The underlying hash algorithm must not require a key */
err = -EINVAL;
if (crypto_shash_alg_needs_key(salg))
goto err_free_inst;
ds = salg->digestsize;
ss = salg->statesize;
if (ds > alg->cra_blocksize ||
ss < alg->cra_blocksize)
goto err_free_inst;
err = crypto_inst_setname(shash_crypto_instance(inst), tmpl->name, alg);
if (err)
goto err_free_inst;
inst->alg.base.cra_priority = alg->cra_priority;
inst->alg.base.cra_blocksize = alg->cra_blocksize;
inst->alg.base.cra_alignmask = alg->cra_alignmask;
ss = ALIGN(ss, alg->cra_alignmask + 1);
inst->alg.digestsize = ds;
inst->alg.statesize = ss;
inst->alg.base.cra_ctxsize = sizeof(struct hmac_ctx) +
ALIGN(ss * 2, crypto_tfm_ctx_alignment());
inst->alg.init = hmac_init;
inst->alg.update = hmac_update;
inst->alg.final = hmac_final;
inst->alg.finup = hmac_finup;
inst->alg.export = hmac_export;
inst->alg.import = hmac_import;
inst->alg.setkey = hmac_setkey;
inst->alg.init_tfm = hmac_init_tfm;
inst->alg.exit_tfm = hmac_exit_tfm;
inst->free = shash_free_singlespawn_instance;
err = shash_register_instance(tmpl, inst);
if (err) {
err_free_inst:
shash_free_singlespawn_instance(inst);
}
return err;
}
static struct crypto_template hmac_tmpl = {
.name = "hmac",
.create = hmac_create,
.module = THIS_MODULE,
};
static int __init hmac_module_init(void)
{
return crypto_register_template(&hmac_tmpl);
}
static void __exit hmac_module_exit(void)
{
crypto_unregister_template(&hmac_tmpl);
}
subsys_initcall(hmac_module_init);
module_exit(hmac_module_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("HMAC hash algorithm");
MODULE_ALIAS_CRYPTO("hmac");
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