#include <crypto/internal/cipher.h>
#include <crypto/internal/hash.h>
#include <crypto/utils.h>
#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/string.h>
struct cmac_tfm_ctx {
struct crypto_cipher *child;
__be64 consts[];
};
static int crypto_cmac_digest_setkey(struct crypto_shash *parent,
const u8 *inkey, unsigned int keylen)
{
struct cmac_tfm_ctx *ctx = crypto_shash_ctx(parent);
unsigned int bs = crypto_shash_blocksize(parent);
__be64 *consts = ctx->consts;
u64 _const[2];
int i, err = 0;
u8 msb_mask, gfmask;
err = crypto_cipher_setkey(ctx->child, inkey, keylen);
if (err)
return err;
memset(consts, 0, bs);
crypto_cipher_encrypt_one(ctx->child, (u8 *)consts, (u8 *)consts);
switch (bs) {
case 16:
gfmask = 0x87;
_const[0] = be64_to_cpu(consts[1]);
_const[1] = be64_to_cpu(consts[0]);
for (i = 0; i < 4; i += 2) {
msb_mask = ((s64)_const[1] >> 63) & gfmask;
_const[1] = (_const[1] << 1) | (_const[0] >> 63);
_const[0] = (_const[0] << 1) ^ msb_mask;
consts[i + 0] = cpu_to_be64(_const[1]);
consts[i + 1] = cpu_to_be64(_const[0]);
}
break;
case 8:
gfmask = 0x1B;
_const[0] = be64_to_cpu(consts[0]);
for (i = 0; i < 2; i++) {
msb_mask = ((s64)_const[0] >> 63) & gfmask;
_const[0] = (_const[0] << 1) ^ msb_mask;
consts[i] = cpu_to_be64(_const[0]);
}
break;
}
return 0;
}
static int crypto_cmac_digest_init(struct shash_desc *pdesc)
{
int bs = crypto_shash_blocksize(pdesc->tfm);
u8 *prev = shash_desc_ctx(pdesc);
memset(prev, 0, bs);
return 0;
}
static int crypto_cmac_digest_update(struct shash_desc *pdesc, const u8 *p,
unsigned int len)
{
struct crypto_shash *parent = pdesc->tfm;
struct cmac_tfm_ctx *tctx = crypto_shash_ctx(parent);
struct crypto_cipher *tfm = tctx->child;
int bs = crypto_shash_blocksize(parent);
u8 *prev = shash_desc_ctx(pdesc);
do {
crypto_xor(prev, p, bs);
crypto_cipher_encrypt_one(tfm, prev, prev);
p += bs;
len -= bs;
} while (len >= bs);
return len;
}
static int crypto_cmac_digest_finup(struct shash_desc *pdesc, const u8 *src,
unsigned int len, u8 *out)
{
struct crypto_shash *parent = pdesc->tfm;
struct cmac_tfm_ctx *tctx = crypto_shash_ctx(parent);
struct crypto_cipher *tfm = tctx->child;
int bs = crypto_shash_blocksize(parent);
u8 *prev = shash_desc_ctx(pdesc);
unsigned int offset = 0;
crypto_xor(prev, src, len);
if (len != bs) {
prev[len] ^= 0x80;
offset += bs;
}
crypto_xor(prev, (const u8 *)tctx->consts + offset, bs);
crypto_cipher_encrypt_one(tfm, out, prev);
return 0;
}
static int cmac_init_tfm(struct crypto_shash *tfm)
{
struct shash_instance *inst = shash_alg_instance(tfm);
struct cmac_tfm_ctx *ctx = crypto_shash_ctx(tfm);
struct crypto_cipher_spawn *spawn;
struct crypto_cipher *cipher;
spawn = shash_instance_ctx(inst);
cipher = crypto_spawn_cipher(spawn);
if (IS_ERR(cipher))
return PTR_ERR(cipher);
ctx->child = cipher;
return 0;
}
static int cmac_clone_tfm(struct crypto_shash *tfm, struct crypto_shash *otfm)
{
struct cmac_tfm_ctx *octx = crypto_shash_ctx(otfm);
struct cmac_tfm_ctx *ctx = crypto_shash_ctx(tfm);
struct crypto_cipher *cipher;
cipher = crypto_clone_cipher(octx->child);
if (IS_ERR(cipher))
return PTR_ERR(cipher);
ctx->child = cipher;
return 0;
}
static void cmac_exit_tfm(struct crypto_shash *tfm)
{
struct cmac_tfm_ctx *ctx = crypto_shash_ctx(tfm);
crypto_free_cipher(ctx->child);
}
static int cmac_create(struct crypto_template *tmpl, struct rtattr **tb)
{
struct shash_instance *inst;
struct crypto_cipher_spawn *spawn;
struct crypto_alg *alg;
u32 mask;
int err;
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_cipher(spawn, shash_crypto_instance(inst),
crypto_attr_alg_name(tb[1]), 0, mask);
if (err)
goto err_free_inst;
alg = crypto_spawn_cipher_alg(spawn);
switch (alg->cra_blocksize) {
case 16:
case 8:
break;
default:
err = -EINVAL;
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_ctxsize = sizeof(struct cmac_tfm_ctx) +
alg->cra_blocksize * 2;
inst->alg.base.cra_flags = CRYPTO_AHASH_ALG_BLOCK_ONLY |
CRYPTO_AHASH_ALG_FINAL_NONZERO;
inst->alg.digestsize = alg->cra_blocksize;
inst->alg.descsize = alg->cra_blocksize;
inst->alg.init = crypto_cmac_digest_init;
inst->alg.update = crypto_cmac_digest_update;
inst->alg.finup = crypto_cmac_digest_finup;
inst->alg.setkey = crypto_cmac_digest_setkey;
inst->alg.init_tfm = cmac_init_tfm;
inst->alg.clone_tfm = cmac_clone_tfm;
inst->alg.exit_tfm = cmac_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 crypto_cmac_tmpl = {
.name = "cmac",
.create = cmac_create,
.module = THIS_MODULE,
};
static int __init crypto_cmac_module_init(void)
{
return crypto_register_template(&crypto_cmac_tmpl);
}
static void __exit crypto_cmac_module_exit(void)
{
crypto_unregister_template(&crypto_cmac_tmpl);
}
module_init(crypto_cmac_module_init);
module_exit(crypto_cmac_module_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("CMAC keyed hash algorithm");
MODULE_ALIAS_CRYPTO("cmac");
MODULE_IMPORT_NS("CRYPTO_INTERNAL");
