path: root/crypto/ccm.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * CCM: Counter with CBC-MAC
 *
 * (C) Copyright IBM Corp. 2007 - Joy Latten <latten@us.ibm.com>
 */

#include <crypto/internal/aead.h>
#include <crypto/internal/hash.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>

struct ccm_instance_ctx {
	struct crypto_skcipher_spawn ctr;
	struct crypto_ahash_spawn mac;
};

struct crypto_ccm_ctx {
	struct crypto_ahash *mac;
	struct crypto_skcipher *ctr;
};

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

struct crypto_rfc4309_req_ctx {
	struct scatterlist src[3];
	struct scatterlist dst[3];
	struct aead_request subreq;
};

struct crypto_ccm_req_priv_ctx {
	u8 odata[16];
	u8 idata[16];
	u8 auth_tag[16];
	u32 flags;
	struct scatterlist src[3];
	struct scatterlist dst[3];
	union {
		struct ahash_request ahreq;
		struct skcipher_request skreq;
	};
};

struct cbcmac_tfm_ctx {
	struct crypto_cipher *child;
};

struct cbcmac_desc_ctx {
	unsigned int len;
};

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_skcipher *ctr = ctx->ctr;
	struct crypto_ahash *mac = ctx->mac;
	int err;

	crypto_skcipher_clear_flags(ctr, CRYPTO_TFM_REQ_MASK);
	crypto_skcipher_set_flags(ctr, crypto_aead_get_flags(aead) &
				       CRYPTO_TFM_REQ_MASK);
	err = crypto_skcipher_setkey(ctr, key, keylen);
	if (err)
		return err;

	crypto_ahash_clear_flags(mac, CRYPTO_TFM_REQ_MASK);
	crypto_ahash_set_flags(mac, crypto_aead_get_flags(aead) &
				    CRYPTO_TFM_REQ_MASK);
	return crypto_ahash_setkey(mac, key, keylen);
}

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 int crypto_ccm_auth(struct aead_request *req, struct scatterlist *plain,
			   unsigned int cryptlen)
{
	struct crypto_ccm_req_priv_ctx *pctx = crypto_ccm_reqctx(req);
	struct crypto_aead *aead = crypto_aead_reqtfm(req);
	struct crypto_ccm_ctx *ctx = crypto_aead_ctx(aead);
	struct ahash_request *ahreq = &pctx->ahreq;
	unsigned int assoclen = req->assoclen;
	struct scatterlist sg[3];
	u8 *odata = pctx->odata;
	u8 *idata = pctx->idata;
	int ilen, err;

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

	sg_init_table(sg, 3);
	sg_set_buf(&sg[0], odata, 16);

	/* format associated data and compute into mac */
	if (assoclen) {
		ilen = format_adata(idata, assoclen);
		sg_set_buf(&sg[1], idata, ilen);
		sg_chain(sg, 3, req->src);
	} else {
		ilen = 0;
		sg_chain(sg, 2, req->src);
	}

	ahash_request_set_tfm(ahreq, ctx->mac);
	ahash_request_set_callback(ahreq, pctx->flags, NULL, NULL);
	ahash_request_set_crypt(ahreq