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/*
* 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
*
* 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.
*
*/

#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/slab.h>
#include <linux/string.h>

struct hmac_ctx {
struct crypto_hash *child;
};

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_hash *tfm)
{
return align_ptr(crypto_hash_ctx_aligned(tfm) +
crypto_hash_blocksize(tfm) * 2 +
crypto_hash_digestsize(tfm), sizeof(void *));
}

static int hmac_setkey(struct crypto_hash *parent,
const u8 *inkey, unsigned int keylen)
{
int bs = crypto_hash_blocksize(parent);
int ds = crypto_hash_digestsize(parent);
char *ipad = crypto_hash_ctx_aligned(parent);
char *opad = ipad + bs;
char *digest = opad + bs;
struct hmac_ctx *ctx = align_ptr(digest + ds, sizeof(void *));
struct crypto_hash *tfm = ctx->child;
unsigned int i;

if (keylen > bs) {
struct hash_desc desc;
struct scatterlist tmp;
int tmplen;
int err;

desc.tfm = tfm;
desc.flags = crypto_hash_get_flags(parent);
desc.flags &= CRYPTO_TFM_REQ_MAY_SLEEP;

err = crypto_hash_init(&desc);
if (err)
return err;

tmplen = bs * 2 + ds;
sg_init_one(&tmp, ipad, tmplen);

for (; keylen > tmplen; inkey += tmplen, keylen -= tmplen) {
memcpy(ipad, inkey, tmplen);
err = crypto_hash_update(&desc, &tmp, tmplen);
if (err)
return err;
}

if (keylen) {
memcpy(ipad, inkey, keylen);
err = crypto_hash_update(&desc, &tmp, keylen);
if (err)
return err;
}

err = crypto_hash_final(&desc, digest);
if (err)
return err;

inkey = digest;
keylen = ds;
}

memcpy(ipad, inkey, keylen);
memset(ipad + keylen, 0, bs - keylen);
memcpy(opad, ipad, bs);

for (i = 0; i < bs; i++) {
ipad[i] ^= 0x36;
opad[i] ^= 0x5c;
}

return 0;
}

static int hmac_init(struct hash_desc *pdesc)
{
struct crypto_hash *parent = pdesc->tfm;
int bs = crypto_hash_blocksize(parent);
int ds = crypto_hash_digestsize(parent);
char *ipad = crypto_hash_ctx_aligned(parent);
struct hmac_ctx *ctx = align_ptr(ipad + bs * 2 + ds, sizeof(void *));
struct hash_desc desc;
struct scatterlist tmp;
int err;

desc.tfm = ctx->child;
desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
sg_init_one(&tmp, ipad, bs);

err = crypto_hash_init(&desc);
if (unlikely(err))
return err;

return crypto_hash_update(&desc, &tmp, bs);
}

static int hmac_update(struct hash_desc *pdesc,
struct scatterlist *sg, unsigned int nbytes)
{
struct hmac_ctx *ctx = hmac_ctx(pdesc->tfm);
struct hash_desc desc;

desc.tfm = ctx->child;
desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;

return crypto_hash_update(&desc, sg, nbytes);
}

static int hmac_final(struct hash_desc *pdesc, u8 *out)
{
struct crypto_hash *parent = pdesc->tfm;
int bs = crypto_hash_blocksize(parent);
int ds = crypto_hash_digestsize(parent);
char *opad = crypto_hash_ctx_aligned(parent) + bs;
char *digest = opad + bs;
struct hmac_ctx *ctx = align_ptr(digest + ds, sizeof(void *));
struct hash_desc desc;
struct scatterlist tmp;
int err;

desc.tfm = ctx->child;
desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;
sg_init_one(&tmp, opad, bs + ds);

err = crypto_hash_final(&desc, digest);
if (unlikely(err))
return err;

return crypto_hash_digest(&desc, &tmp, bs + ds, out);
}

static int hmac_digest(struct hash_desc *pdesc, struct scatterlist *sg,
unsigned int nbytes, u8 *out)
{
struct crypto_hash *parent = pdesc->tfm;
int bs = crypto_hash_blocksize(parent);
int ds = crypto_hash_digestsize(parent);
char *ipad = crypto_hash_ctx_aligned(parent);
char *opad = ipad + bs;
char *digest = opad + bs;
struct hmac_ctx *ctx = align_ptr(digest + ds, sizeof(void *));
struct hash_desc desc;
struct scatterlist sg1[2];
struct scatterlist sg2[1];
int err;

desc.tfm = ctx->child;
desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP;

sg_init_table(sg1, 2);
sg_set_buf(sg1, ipad, bs);
scatterwalk_sg_chain(sg1, 2, sg);

sg_init_table(sg2, 1);
sg_set_buf(sg2, opad, bs + ds);

err = crypto_hash_digest(&desc, sg1, nbytes + bs, digest);
if (unlikely(err))
return err;

return crypto_hash_digest(&desc, sg2, bs + ds, out);
}

static int hmac_init_tfm(struct crypto_tfm *tfm)
{
struct crypto_hash *hash;
struct crypto_instance *inst = (void *)tfm->__crt_alg;
struct crypto_spawn *spawn = crypto_instance_ctx(inst);
struct hmac_ctx *ctx = hmac_ctx(__crypto_hash_cast(tfm));

hash = crypto_spawn_hash(spawn);
if (IS_ERR(hash))
return PTR_ERR(hash);

ctx->child = hash;
return 0;
}

static void hmac_exit_tfm(struct crypto_tfm *tfm)
{
struct hmac_ctx *ctx = hmac_ctx(__crypto_hash_cast(tfm));
crypto_free_hash(ctx->child);
}

static void hmac_free(struct crypto_instance *inst)
{
crypto_drop_spawn(crypto_instance_ctx(inst));
kfree(inst);
}

static struct crypto_instance *hmac_alloc(struct rtattr **tb)
{
struct crypto_instance *inst;
struct crypto_alg *alg;
int err;
int ds;

err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_HASH);
if (err)
return ERR_PTR(err);

alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_HASH,
CRYPTO_ALG_TYPE_HASH_MASK);
if (IS_ERR(alg))
return ERR_CAST(alg);

inst = ERR_PTR(-EINVAL);
ds = alg->cra_type == &crypto_hash_type ?
alg->cra_hash.digestsize :
alg->cra_type ?
__crypto_shash_alg(alg)->digestsize :
alg->cra_digest.dia_digestsize;
if (ds > alg->cra_blocksize)
goto out_put_alg;

inst = crypto_alloc_instance("hmac", alg);
if (IS_ERR(inst))
goto out_put_alg;

inst->alg.cra_flags = CRYPTO_ALG_TYPE_HASH;
inst->alg.cra_priority = alg->cra_priority;
inst->alg.cra_blocksize = alg->cra_blocksize;
inst->alg.cra_alignmask = alg->cra_alignmask;
inst->alg.cra_type = &crypto_hash_type;

inst->alg.cra_hash.digestsize = ds;

inst->alg.cra_ctxsize = sizeof(struct hmac_ctx) +
ALIGN(inst->alg.cra_blocksize * 2 + ds,
sizeof(void *));

inst->alg.cra_init = hmac_init_tfm;
inst->alg.cra_exit = hmac_exit_tfm;

inst->alg.cra_hash.init = hmac_init;
inst->alg.cra_hash.update = hmac_update;
inst->alg.cra_hash.final = hmac_final;
inst->alg.cra_hash.digest = hmac_digest;
inst->alg.cra_hash.setkey = hmac_setkey;

out_put_alg:
crypto_mod_put(alg);
return inst;
}

static struct crypto_template hmac_tmpl = {
.name = "hmac",
.alloc = hmac_alloc,
.free = hmac_free,
.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);
}

module_init(hmac_module_init);
module_exit(hmac_module_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("HMAC hash algorithm");
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