Revision 00d8689b85a7bb37cc57ba4c40bd46325f51ced4 authored by Thomas Petazzoni on 11 December 2014, 16:33:46 UTC, committed by Wolfram Sang on 17 December 2014, 18:26:03 UTC
Originally, the I2C controller supported by the i2c-mv64xxx driver
requires a lot of software support: an interrupt is generated at each
step of an I2C transaction (after the start bit, after sending the
address, etc.) and the driver is in charge of re-programming the I2C
controller to do the next step of the I2C transaction. This explains
the fairly complex state machine that the driver has.

On Marvell Armada XP and later processors (Armada 375, 38x, etc.), the
I2C controller was extended with a part called the "I2C Bridge", which
allows to offload the I2C transaction completely to the
hardware. Initial support for this mechanism was added in commit
930ab3d403a ("i2c: mv64xxx: Add I2C Transaction Generator support").

However, the implementation done in this commit has two related
issues, which this commit fixes by completely changing how the offload
implementation is done:

 * SMBus read transfers, where there is one write to select the
   register immediately followed in the same transaction by one read,
   were making the processor hang. This was easier visible on the
   Marvell Armada XP WRT1900AC platform using a driver for an I2C LED
   controller, or on other Armada XP platforms by using a simple
   'i2cget' command to read an I2C EEPROM.

 * The implementation was based on the fact that the offload engine
   was re-programmed to transfer each message of an I2C xfer: this
   meant that each message sent with the offload engine was starting
   with a normal I2C start sequence. However, the I2C subsystem
   assumes that all messages belonging to the same xfer will use the
   so-called "repeated start" so that the entire I2C xfer is seen as
   one transfer by the I2C devices and cannot be interrupt by other
   I2C masters on the same bus.

In fact, the "I2C Bridge" allows to offload three types of xfer:

 - xfer of one write message
 - xfer of one read message
 - xfer of one write message followed by one read message

For all other situations, we have to fallback to not using the "I2C
Bridge" in order to get proper I2C semantics.

Therefore, this commit reworks the offload implementation to put it
not at the message level, but at the xfer level: in the
mv64xxx_i2c_xfer() function, we decide if the transaction can be
offloaded (in which case it is handled by the
mv64xxx_i2c_offload_xfer() function), or otherwise it is handled by
the slow path (implemented in the existing mv64xxx_i2c_execute_msg()).

This allows to simplify the state machine, which no longer needs to
have any state related to the offload implementation: the offload
implementation is now completely separated from the slow path (with
the exception of the interrupt handler, of course).

In summary:

 - mv64xxx_i2c_can_offload() will analyze an I2C xfer and decided of
   the "I2C Bridge" can be used to offload it or not.

 - mv64xxx_i2c_offload_xfer() will actually program the "I2C Bridge"
   to offload one xfer (of either one or two messages), and block
   using mv64xxx_i2c_wait_for_completion() until the xfer completes.

 - The interrupt handler mv64xxx_i2c_intr() is modified to push the
   offload related code to a separate function,
   mv64xxx_i2c_intr_offload(). It will take care of reading the
   received data if needed.

This commit was tested on:

 - Armada XP OpenBlocks AX3-4 (EEPROM on I2C and RTC on I2C)
 - Armada XP WRT1900AC (LED controller on I2C)
 - Armada XP GP (EEPROM on I2C)

Fixes: 930ab3d403ae ("i2c: mv64xxx: Add I2C Transaction Generator support")
Cc: <stable@vger.kernel.org> # v3.12+
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
[wsa: fixed checkpatch warnings]
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
1 parent 1259869
Raw File
ccm.c
/*
 * CCM: Counter with CBC-MAC
 *
 * (C) Copyright IBM Corp. 2007 - Joy Latten <latten@us.ibm.com>
 *
 * 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/aead.h>
#include <crypto/internal/skcipher.h>
#include <crypto/scatterwalk.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>

#include "internal.h"

struct ccm_instance_ctx {
	struct crypto_skcipher_spawn ctr;
	struct crypto_spawn cipher;
};

struct crypto_ccm_ctx {
	struct crypto_cipher *cipher;
	struct crypto_ablkcipher *ctr;
};

struct crypto_rfc4309_ctx {
	struct crypto_aead *child;
	u8 nonce[3];
};

struct crypto_ccm_req_priv_ctx {
	u8 odata[16];
	u8 idata[16];
	u8 auth_tag[16];
	u32 ilen;
	u32 flags;
	struct scatterlist src[2];
	struct scatterlist dst[2];
	struct ablkcipher_request abreq;
};

static inline struct crypto_ccm_req_priv_ctx *crypto_ccm_reqctx(
	struct aead_request *req)
{
	unsigned long align = crypto_aead_alignmask(crypto_aead_reqtfm(req));

	return (void *)PTR_ALIGN((u8 *)aead_request_ctx(req), align + 1);
}

static int set_msg_len(u8 *block, unsigned int msglen, int csize)
{
	__be32 data;

	memset(block, 0, csize);
	block += csize;

	if (csize >= 4)
		csize = 4;
	else if (msglen > (1 << (8 * csize)))
		return -EOVERFLOW;

	data = cpu_to_be32(msglen);
	memcpy(block - csize, (u8 *)&data + 4 - csize, csize);

	return 0;
}

static int crypto_ccm_setkey(struct crypto_aead *aead, const u8 *key,
			     unsigned int keylen)
{
	struct crypto_ccm_ctx *ctx = crypto_aead_ctx(aead);
	struct crypto_ablkcipher *ctr = ctx->ctr;
	struct crypto_cipher *tfm = ctx->cipher;
	int err = 0;

	crypto_ablkcipher_clear_flags(ctr, CRYPTO_TFM_REQ_MASK);
	crypto_ablkcipher_set_flags(ctr, crypto_aead_get_flags(aead) &
				    CRYPTO_TFM_REQ_MASK);
	err = crypto_ablkcipher_setkey(ctr, key, keylen);
	crypto_aead_set_flags(aead, crypto_ablkcipher_get_flags(ctr) &
			      CRYPTO_TFM_RES_MASK);
	if (err)
		goto out;

	crypto_cipher_clear_flags(tfm, CRYPTO_TFM_REQ_MASK);
	crypto_cipher_set_flags(tfm, crypto_aead_get_flags(aead) &
				    CRYPTO_TFM_REQ_MASK);
	err = crypto_cipher_setkey(tfm, key, keylen);
	crypto_aead_set_flags(aead, crypto_cipher_get_flags(tfm) &
			      CRYPTO_TFM_RES_MASK);

out:
	return err;
}

static int crypto_ccm_setauthsize(struct crypto_aead *tfm,
				  unsigned int authsize)
{
	switch (authsize) {
	case 4:
	case 6:
	case 8:
	case 10:
	case 12:
	case 14:
	case 16:
		break;
	default:
		return -EINVAL;
	}

	return 0;
}

static int format_input(u8 *info, struct aead_request *req,
			unsigned int cryptlen)
{
	struct crypto_aead *aead = crypto_aead_reqtfm(req);
	unsigned int lp = req->iv[0];
	unsigned int l = lp + 1;
	unsigned int m;

	m = crypto_aead_authsize(aead);

	memcpy(info, req->iv, 16);

	/* format control info per RFC 3610 and
	 * NIST Special Publication 800-38C
	 */
	*info |= (8 * ((m - 2) / 2));
	if (req->assoclen)
		*info |= 64;

	return set_msg_len(info + 16 - l, cryptlen, l);
}

static int format_adata(u8 *adata, unsigned int a)
{
	int len = 0;

	/* add control info for associated data
	 * RFC 3610 and NIST Special Publication 800-38C
	 */
	if (a < 65280) {
		*(__be16 *)adata = cpu_to_be16(a);
		len = 2;
	} else  {
		*(__be16 *)adata = cpu_to_be16(0xfffe);
		*(__be32 *)&adata[2] = cpu_to_be32(a);
		len = 6;
	}

	return len;
}

static void compute_mac(struct crypto_cipher *tfm, u8 *data, int n,
		       struct crypto_ccm_req_priv_ctx *pctx)
{
	unsigned int bs = 16;
	u8 *odata = pctx->odata;
	u8 *idata = pctx->idata;
	int datalen, getlen;

	datalen = n;

	/* first time in here, block may be partially filled. */
	getlen = bs - pctx->ilen;
	if (datalen >= getlen) {
		memcpy(idata + pctx->ilen, data, getlen);
		crypto_xor(odata, idata, bs);
		crypto_cipher_encrypt_one(tfm, odata, odata);
		datalen -= getlen;
		data += getlen;
		pctx->ilen = 0;
	}

	/* now encrypt rest of data */
	while (datalen >= bs) {
		crypto_xor(odata, data, bs);
		crypto_cipher_encrypt_one(tfm, odata, odata);

		datalen -= bs;
		data += bs;
	}

	/* check and see if there's leftover data that wasn't
	 * enough to fill a block.
	 */
	if (datalen) {
		memcpy(idata + pctx->ilen, data, datalen);
		pctx->ilen += datalen;
	}
}

static void get_data_to_compute(struct crypto_cipher *tfm,
			       struct crypto_ccm_req_priv_ctx *pctx,
			       struct scatterlist *sg, unsigned int len)
{
	struct scatter_walk walk;
	u8 *data_src;
	int n;

	scatterwalk_start(&walk, sg);

	while (len) {
		n = scatterwalk_clamp(&walk, len);
		if (!n) {
			scatterwalk_start(&walk, sg_next(walk.sg));
			n = scatterwalk_clamp(&walk, len);
		}
		data_src = scatterwalk_map(&walk);

		compute_mac(tfm, data_src, n, pctx);
		len -= n;

		scatterwalk_unmap(data_src);
		scatterwalk_advance(&walk, n);
		scatterwalk_done(&walk, 0, len);
		if (len)
			crypto_yield(pctx->flags);
	}

	/* any leftover needs padding and then encrypted */
	if (pctx->ilen) {
		int padlen;
		u8 *odata = pctx->odata;
		u8 *idata = pctx->idata;

		padlen = 16 - pctx->ilen;
		memset(idata + pctx->ilen, 0, padlen);
		crypto_xor(odata, idata, 16);
		crypto_cipher_encrypt_one(tfm, odata, odata);
		pctx->ilen = 0;
	}
}

static int crypto_ccm_auth(struct aead_request *req, struct scatterlist *plain,
			   unsigned int cryptlen)
{
	struct crypto_aead *aead = crypto_aead_reqtfm(req);
	struct crypto_ccm_ctx *ctx = crypto_aead_ctx(aead);
	struct crypto_ccm_req_priv_ctx *pctx = crypto_ccm_reqctx(req);
	struct crypto_cipher *cipher = ctx->cipher;
	unsigned int assoclen = req->assoclen;
	u8 *odata = pctx->odata;
	u8 *idata = pctx->idata;
	int err;

	/* format control data for input */
	err = format_input(odata, req, cryptlen);
	if (err)
		goto out;

	/* encrypt first block to use as start in computing mac  */
	crypto_cipher_encrypt_one(cipher, odata, odata);

	/* format associated data and compute into mac */
	if (assoclen) {
		pctx->ilen = format_adata(idata, assoclen);
		get_data_to_compute(cipher, pctx, req->assoc, req->assoclen);
	} else {
		pctx->ilen = 0;
	}

	/* compute plaintext into mac */
	if (cryptlen)
		get_data_to_compute(cipher, pctx, plain, cryptlen);

out:
	return err;
}

static void crypto_ccm_encrypt_done(struct crypto_async_request *areq, int err)
{
	struct aead_request *req = areq->data;
	struct crypto_aead *aead = crypto_aead_reqtfm(req);
	struct crypto_ccm_req_priv_ctx *pctx = crypto_ccm_reqctx(req);
	u8 *odata = pctx->odata;

	if (!err)
		scatterwalk_map_and_copy(odata, req->dst, req->cryptlen,
					 crypto_aead_authsize(aead), 1);
	aead_request_complete(req, err);
}

static inline int crypto_ccm_check_iv(const u8 *iv)
{
	/* 2 <= L <= 8, so 1 <= L' <= 7. */
	if (1 > iv[0] || iv[0] > 7)
		return -EINVAL;

	return 0;
}

static int crypto_ccm_encrypt(struct aead_request *req)
{
	struct crypto_aead *aead = crypto_aead_reqtfm(req);
	struct crypto_ccm_ctx *ctx = crypto_aead_ctx(aead);
	struct crypto_ccm_req_priv_ctx *pctx = crypto_ccm_reqctx(req);
	struct ablkcipher_request *abreq = &pctx->abreq;
	struct scatterlist *dst;
	unsigned int cryptlen = req->cryptlen;
	u8 *odata = pctx->odata;
	u8 *iv = req->iv;
	int err;

	err = crypto_ccm_check_iv(iv);
	if (err)
		return err;

	pctx->flags = aead_request_flags(req);

	err = crypto_ccm_auth(req, req->src, cryptlen);
	if (err)
		return err;

	 /* Note: rfc 3610 and NIST 800-38C require counter of
	 * zero to encrypt auth tag.
	 */
	memset(iv + 15 - iv[0], 0, iv[0] + 1);

	sg_init_table(pctx->src, 2);
	sg_set_buf(pctx->src, odata, 16);
	scatterwalk_sg_chain(pctx->src, 2, req->src);

	dst = pctx->src;
	if (req->src != req->dst) {
		sg_init_table(pctx->dst, 2);
		sg_set_buf(pctx->dst, odata, 16);
		scatterwalk_sg_chain(pctx->dst, 2, req->dst);
		dst = pctx->dst;
	}

	ablkcipher_request_set_tfm(abreq, ctx->ctr);
	ablkcipher_request_set_callback(abreq, pctx->flags,
					crypto_ccm_encrypt_done, req);
	ablkcipher_request_set_crypt(abreq, pctx->src, dst, cryptlen + 16, iv);
	err = crypto_ablkcipher_encrypt(abreq);
	if (err)
		return err;

	/* copy authtag to end of dst */
	scatterwalk_map_and_copy(odata, req->dst, cryptlen,
				 crypto_aead_authsize(aead), 1);
	return err;
}

static void crypto_ccm_decrypt_done(struct crypto_async_request *areq,
				   int err)
{
	struct aead_request *req = areq->data;
	struct crypto_ccm_req_priv_ctx *pctx = crypto_ccm_reqctx(req);
	struct crypto_aead *aead = crypto_aead_reqtfm(req);
	unsigned int authsize = crypto_aead_authsize(aead);
	unsigned int cryptlen = req->cryptlen - authsize;

	if (!err) {
		err = crypto_ccm_auth(req, req->dst, cryptlen);
		if (!err && crypto_memneq(pctx->auth_tag, pctx->odata, authsize))
			err = -EBADMSG;
	}
	aead_request_complete(req, err);
}

static int crypto_ccm_decrypt(struct aead_request *req)
{
	struct crypto_aead *aead = crypto_aead_reqtfm(req);
	struct crypto_ccm_ctx *ctx = crypto_aead_ctx(aead);
	struct crypto_ccm_req_priv_ctx *pctx = crypto_ccm_reqctx(req);
	struct ablkcipher_request *abreq = &pctx->abreq;
	struct scatterlist *dst;
	unsigned int authsize = crypto_aead_authsize(aead);
	unsigned int cryptlen = req->cryptlen;
	u8 *authtag = pctx->auth_tag;
	u8 *odata = pctx->odata;
	u8 *iv = req->iv;
	int err;

	if (cryptlen < authsize)
		return -EINVAL;
	cryptlen -= authsize;

	err = crypto_ccm_check_iv(iv);
	if (err)
		return err;

	pctx->flags = aead_request_flags(req);

	scatterwalk_map_and_copy(authtag, req->src, cryptlen, authsize, 0);

	memset(iv + 15 - iv[0], 0, iv[0] + 1);

	sg_init_table(pctx->src, 2);
	sg_set_buf(pctx->src, authtag, 16);
	scatterwalk_sg_chain(pctx->src, 2, req->src);

	dst = pctx->src;
	if (req->src != req->dst) {
		sg_init_table(pctx->dst, 2);
		sg_set_buf(pctx->dst, authtag, 16);
		scatterwalk_sg_chain(pctx->dst, 2, req->dst);
		dst = pctx->dst;
	}

	ablkcipher_request_set_tfm(abreq, ctx->ctr);
	ablkcipher_request_set_callback(abreq, pctx->flags,
					crypto_ccm_decrypt_done, req);
	ablkcipher_request_set_crypt(abreq, pctx->src, dst, cryptlen + 16, iv);
	err = crypto_ablkcipher_decrypt(abreq);
	if (err)
		return err;

	err = crypto_ccm_auth(req, req->dst, cryptlen);
	if (err)
		return err;

	/* verify */
	if (crypto_memneq(authtag, odata, authsize))
		return -EBADMSG;

	return err;
}

static int crypto_ccm_init_tfm(struct crypto_tfm *tfm)
{
	struct crypto_instance *inst = (void *)tfm->__crt_alg;
	struct ccm_instance_ctx *ictx = crypto_instance_ctx(inst);
	struct crypto_ccm_ctx *ctx = crypto_tfm_ctx(tfm);
	struct crypto_cipher *cipher;
	struct crypto_ablkcipher *ctr;
	unsigned long align;
	int err;

	cipher = crypto_spawn_cipher(&ictx->cipher);
	if (IS_ERR(cipher))
		return PTR_ERR(cipher);

	ctr = crypto_spawn_skcipher(&ictx->ctr);
	err = PTR_ERR(ctr);
	if (IS_ERR(ctr))
		goto err_free_cipher;

	ctx->cipher = cipher;
	ctx->ctr = ctr;

	align = crypto_tfm_alg_alignmask(tfm);
	align &= ~(crypto_tfm_ctx_alignment() - 1);
	tfm->crt_aead.reqsize = align +
				sizeof(struct crypto_ccm_req_priv_ctx) +
				crypto_ablkcipher_reqsize(ctr);

	return 0;

err_free_cipher:
	crypto_free_cipher(cipher);
	return err;
}

static void crypto_ccm_exit_tfm(struct crypto_tfm *tfm)
{
	struct crypto_ccm_ctx *ctx = crypto_tfm_ctx(tfm);

	crypto_free_cipher(ctx->cipher);
	crypto_free_ablkcipher(ctx->ctr);
}

static struct crypto_instance *crypto_ccm_alloc_common(struct rtattr **tb,
						       const char *full_name,
						       const char *ctr_name,
						       const char *cipher_name)
{
	struct crypto_attr_type *algt;
	struct crypto_instance *inst;
	struct crypto_alg *ctr;
	struct crypto_alg *cipher;
	struct ccm_instance_ctx *ictx;
	int err;

	algt = crypto_get_attr_type(tb);
	if (IS_ERR(algt))
		return ERR_CAST(algt);

	if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
		return ERR_PTR(-EINVAL);

	cipher = crypto_alg_mod_lookup(cipher_name,  CRYPTO_ALG_TYPE_CIPHER,
				       CRYPTO_ALG_TYPE_MASK);
	if (IS_ERR(cipher))
		return ERR_CAST(cipher);

	err = -EINVAL;
	if (cipher->cra_blocksize != 16)
		goto out_put_cipher;

	inst = kzalloc(sizeof(*inst) + sizeof(*ictx), GFP_KERNEL);
	err = -ENOMEM;
	if (!inst)
		goto out_put_cipher;

	ictx = crypto_instance_ctx(inst);

	err = crypto_init_spawn(&ictx->cipher, cipher, inst,
				CRYPTO_ALG_TYPE_MASK);
	if (err)
		goto err_free_inst;

	crypto_set_skcipher_spawn(&ictx->ctr, inst);
	err = crypto_grab_skcipher(&ictx->ctr, ctr_name, 0,
				   crypto_requires_sync(algt->type,
							algt->mask));
	if (err)
		goto err_drop_cipher;

	ctr = crypto_skcipher_spawn_alg(&ictx->ctr);

	/* Not a stream cipher? */
	err = -EINVAL;
	if (ctr->cra_blocksize != 1)
		goto err_drop_ctr;

	/* We want the real thing! */
	if (ctr->cra_ablkcipher.ivsize != 16)
		goto err_drop_ctr;

	err = -ENAMETOOLONG;
	if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
		     "ccm_base(%s,%s)", ctr->cra_driver_name,
		     cipher->cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
		goto err_drop_ctr;

	memcpy(inst->alg.cra_name, full_name, CRYPTO_MAX_ALG_NAME);

	inst->alg.cra_flags = CRYPTO_ALG_TYPE_AEAD;
	inst->alg.cra_flags |= ctr->cra_flags & CRYPTO_ALG_ASYNC;
	inst->alg.cra_priority = cipher->cra_priority + ctr->cra_priority;
	inst->alg.cra_blocksize = 1;
	inst->alg.cra_alignmask = cipher->cra_alignmask | ctr->cra_alignmask |
				  (__alignof__(u32) - 1);
	inst->alg.cra_type = &crypto_aead_type;
	inst->alg.cra_aead.ivsize = 16;
	inst->alg.cra_aead.maxauthsize = 16;
	inst->alg.cra_ctxsize = sizeof(struct crypto_ccm_ctx);
	inst->alg.cra_init = crypto_ccm_init_tfm;
	inst->alg.cra_exit = crypto_ccm_exit_tfm;
	inst->alg.cra_aead.setkey = crypto_ccm_setkey;
	inst->alg.cra_aead.setauthsize = crypto_ccm_setauthsize;
	inst->alg.cra_aead.encrypt = crypto_ccm_encrypt;
	inst->alg.cra_aead.decrypt = crypto_ccm_decrypt;

out:
	crypto_mod_put(cipher);
	return inst;

err_drop_ctr:
	crypto_drop_skcipher(&ictx->ctr);
err_drop_cipher:
	crypto_drop_spawn(&ictx->cipher);
err_free_inst:
	kfree(inst);
out_put_cipher:
	inst = ERR_PTR(err);
	goto out;
}

static struct crypto_instance *crypto_ccm_alloc(struct rtattr **tb)
{
	const char *cipher_name;
	char ctr_name[CRYPTO_MAX_ALG_NAME];
	char full_name[CRYPTO_MAX_ALG_NAME];

	cipher_name = crypto_attr_alg_name(tb[1]);
	if (IS_ERR(cipher_name))
		return ERR_CAST(cipher_name);

	if (snprintf(ctr_name, CRYPTO_MAX_ALG_NAME, "ctr(%s)",
		     cipher_name) >= CRYPTO_MAX_ALG_NAME)
		return ERR_PTR(-ENAMETOOLONG);

	if (snprintf(full_name, CRYPTO_MAX_ALG_NAME, "ccm(%s)", cipher_name) >=
	    CRYPTO_MAX_ALG_NAME)
		return ERR_PTR(-ENAMETOOLONG);

	return crypto_ccm_alloc_common(tb, full_name, ctr_name, cipher_name);
}

static void crypto_ccm_free(struct crypto_instance *inst)
{
	struct ccm_instance_ctx *ctx = crypto_instance_ctx(inst);

	crypto_drop_spawn(&ctx->cipher);
	crypto_drop_skcipher(&ctx->ctr);
	kfree(inst);
}

static struct crypto_template crypto_ccm_tmpl = {
	.name = "ccm",
	.alloc = crypto_ccm_alloc,
	.free = crypto_ccm_free,
	.module = THIS_MODULE,
};

static struct crypto_instance *crypto_ccm_base_alloc(struct rtattr **tb)
{
	const char *ctr_name;
	const char *cipher_name;
	char full_name[CRYPTO_MAX_ALG_NAME];

	ctr_name = crypto_attr_alg_name(tb[1]);
	if (IS_ERR(ctr_name))
		return ERR_CAST(ctr_name);

	cipher_name = crypto_attr_alg_name(tb[2]);
	if (IS_ERR(cipher_name))
		return ERR_CAST(cipher_name);

	if (snprintf(full_name, CRYPTO_MAX_ALG_NAME, "ccm_base(%s,%s)",
		     ctr_name, cipher_name) >= CRYPTO_MAX_ALG_NAME)
		return ERR_PTR(-ENAMETOOLONG);

	return crypto_ccm_alloc_common(tb, full_name, ctr_name, cipher_name);
}

static struct crypto_template crypto_ccm_base_tmpl = {
	.name = "ccm_base",
	.alloc = crypto_ccm_base_alloc,
	.free = crypto_ccm_free,
	.module = THIS_MODULE,
};

static int crypto_rfc4309_setkey(struct crypto_aead *parent, const u8 *key,
				 unsigned int keylen)
{
	struct crypto_rfc4309_ctx *ctx = crypto_aead_ctx(parent);
	struct crypto_aead *child = ctx->child;
	int err;

	if (keylen < 3)
		return -EINVAL;

	keylen -= 3;
	memcpy(ctx->nonce, key + keylen, 3);

	crypto_aead_clear_flags(child, CRYPTO_TFM_REQ_MASK);
	crypto_aead_set_flags(child, crypto_aead_get_flags(parent) &
				     CRYPTO_TFM_REQ_MASK);
	err = crypto_aead_setkey(child, key, keylen);
	crypto_aead_set_flags(parent, crypto_aead_get_flags(child) &
				      CRYPTO_TFM_RES_MASK);

	return err;
}

static int crypto_rfc4309_setauthsize(struct crypto_aead *parent,
				      unsigned int authsize)
{
	struct crypto_rfc4309_ctx *ctx = crypto_aead_ctx(parent);

	switch (authsize) {
	case 8:
	case 12:
	case 16:
		break;
	default:
		return -EINVAL;
	}

	return crypto_aead_setauthsize(ctx->child, authsize);
}

static struct aead_request *crypto_rfc4309_crypt(struct aead_request *req)
{
	struct aead_request *subreq = aead_request_ctx(req);
	struct crypto_aead *aead = crypto_aead_reqtfm(req);
	struct crypto_rfc4309_ctx *ctx = crypto_aead_ctx(aead);
	struct crypto_aead *child = ctx->child;
	u8 *iv = PTR_ALIGN((u8 *)(subreq + 1) + crypto_aead_reqsize(child),
			   crypto_aead_alignmask(child) + 1);

	/* L' */
	iv[0] = 3;

	memcpy(iv + 1, ctx->nonce, 3);
	memcpy(iv + 4, req->iv, 8);

	aead_request_set_tfm(subreq, child);
	aead_request_set_callback(subreq, req->base.flags, req->base.complete,
				  req->base.data);
	aead_request_set_crypt(subreq, req->src, req->dst, req->cryptlen, iv);
	aead_request_set_assoc(subreq, req->assoc, req->assoclen);

	return subreq;
}

static int crypto_rfc4309_encrypt(struct aead_request *req)
{
	req = crypto_rfc4309_crypt(req);

	return crypto_aead_encrypt(req);
}

static int crypto_rfc4309_decrypt(struct aead_request *req)
{
	req = crypto_rfc4309_crypt(req);

	return crypto_aead_decrypt(req);
}

static int crypto_rfc4309_init_tfm(struct crypto_tfm *tfm)
{
	struct crypto_instance *inst = (void *)tfm->__crt_alg;
	struct crypto_aead_spawn *spawn = crypto_instance_ctx(inst);
	struct crypto_rfc4309_ctx *ctx = crypto_tfm_ctx(tfm);
	struct crypto_aead *aead;
	unsigned long align;

	aead = crypto_spawn_aead(spawn);
	if (IS_ERR(aead))
		return PTR_ERR(aead);

	ctx->child = aead;

	align = crypto_aead_alignmask(aead);
	align &= ~(crypto_tfm_ctx_alignment() - 1);
	tfm->crt_aead.reqsize = sizeof(struct aead_request) +
				ALIGN(crypto_aead_reqsize(aead),
				      crypto_tfm_ctx_alignment()) +
				align + 16;

	return 0;
}

static void crypto_rfc4309_exit_tfm(struct crypto_tfm *tfm)
{
	struct crypto_rfc4309_ctx *ctx = crypto_tfm_ctx(tfm);

	crypto_free_aead(ctx->child);
}

static struct crypto_instance *crypto_rfc4309_alloc(struct rtattr **tb)
{
	struct crypto_attr_type *algt;
	struct crypto_instance *inst;
	struct crypto_aead_spawn *spawn;
	struct crypto_alg *alg;
	const char *ccm_name;
	int err;

	algt = crypto_get_attr_type(tb);
	if (IS_ERR(algt))
		return ERR_CAST(algt);

	if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
		return ERR_PTR(-EINVAL);

	ccm_name = crypto_attr_alg_name(tb[1]);
	if (IS_ERR(ccm_name))
		return ERR_CAST(ccm_name);

	inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
	if (!inst)
		return ERR_PTR(-ENOMEM);

	spawn = crypto_instance_ctx(inst);
	crypto_set_aead_spawn(spawn, inst);
	err = crypto_grab_aead(spawn, ccm_name, 0,
			       crypto_requires_sync(algt->type, algt->mask));
	if (err)
		goto out_free_inst;

	alg = crypto_aead_spawn_alg(spawn);

	err = -EINVAL;

	/* We only support 16-byte blocks. */
	if (alg->cra_aead.ivsize != 16)
		goto out_drop_alg;

	/* Not a stream cipher? */
	if (alg->cra_blocksize != 1)
		goto out_drop_alg;

	err = -ENAMETOOLONG;
	if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME,
		     "rfc4309(%s)", alg->cra_name) >= CRYPTO_MAX_ALG_NAME ||
	    snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
		     "rfc4309(%s)", alg->cra_driver_name) >=
	    CRYPTO_MAX_ALG_NAME)
		goto out_drop_alg;

	inst->alg.cra_flags = CRYPTO_ALG_TYPE_AEAD;
	inst->alg.cra_flags |= alg->cra_flags & CRYPTO_ALG_ASYNC;
	inst->alg.cra_priority = alg->cra_priority;
	inst->alg.cra_blocksize = 1;
	inst->alg.cra_alignmask = alg->cra_alignmask;
	inst->alg.cra_type = &crypto_nivaead_type;

	inst->alg.cra_aead.ivsize = 8;
	inst->alg.cra_aead.maxauthsize = 16;

	inst->alg.cra_ctxsize = sizeof(struct crypto_rfc4309_ctx);

	inst->alg.cra_init = crypto_rfc4309_init_tfm;
	inst->alg.cra_exit = crypto_rfc4309_exit_tfm;

	inst->alg.cra_aead.setkey = crypto_rfc4309_setkey;
	inst->alg.cra_aead.setauthsize = crypto_rfc4309_setauthsize;
	inst->alg.cra_aead.encrypt = crypto_rfc4309_encrypt;
	inst->alg.cra_aead.decrypt = crypto_rfc4309_decrypt;

	inst->alg.cra_aead.geniv = "seqiv";

out:
	return inst;

out_drop_alg:
	crypto_drop_aead(spawn);
out_free_inst:
	kfree(inst);
	inst = ERR_PTR(err);
	goto out;
}

static void crypto_rfc4309_free(struct crypto_instance *inst)
{
	crypto_drop_spawn(crypto_instance_ctx(inst));
	kfree(inst);
}

static struct crypto_template crypto_rfc4309_tmpl = {
	.name = "rfc4309",
	.alloc = crypto_rfc4309_alloc,
	.free = crypto_rfc4309_free,
	.module = THIS_MODULE,
};

static int __init crypto_ccm_module_init(void)
{
	int err;

	err = crypto_register_template(&crypto_ccm_base_tmpl);
	if (err)
		goto out;

	err = crypto_register_template(&crypto_ccm_tmpl);
	if (err)
		goto out_undo_base;

	err = crypto_register_template(&crypto_rfc4309_tmpl);
	if (err)
		goto out_undo_ccm;

out:
	return err;

out_undo_ccm:
	crypto_unregister_template(&crypto_ccm_tmpl);
out_undo_base:
	crypto_unregister_template(&crypto_ccm_base_tmpl);
	goto out;
}

static void __exit crypto_ccm_module_exit(void)
{
	crypto_unregister_template(&crypto_rfc4309_tmpl);
	crypto_unregister_template(&crypto_ccm_tmpl);
	crypto_unregister_template(&crypto_ccm_base_tmpl);
}

module_init(crypto_ccm_module_init);
module_exit(crypto_ccm_module_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Counter with CBC MAC");
MODULE_ALIAS_CRYPTO("ccm_base");
MODULE_ALIAS_CRYPTO("rfc4309");
MODULE_ALIAS_CRYPTO("ccm");
back to top