Commit message: crypto: ccm - move cbcmac input off the stack

Commit f15f05b0a5de ("crypto: ccm - switch to separate cbcmac driver")
refactored the CCM driver to allow separate implementations of the
underlying MAC to be provided by a platform. However, in doing so, it
moved some data from the linear region to the stack, which violates the
SG constraints when the stack is virtually mapped.

So move idata/odata back to the request ctx struct, of which we can
reasonably expect that it has been allocated using kmalloc() et al.

Reported-by: Johannes Berg <johannes@sipsolutions.net>
Fixes: f15f05b0a5de ("crypto: ccm - switch to separate cbcmac driver")
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
CVE: CVE-2017-8065
CWE: CWE-119
Vulnerability description: crypto/ccm.c in the Linux kernel 4.9.x and 4.10.x through 4.10.12 interacts incorrectly with the CONFIG_VMAP_STACK option, which allows local users to cause a denial of service (system crash or memory corruption) or possibly have unspecified other impact by leveraging use of more than one virtual page for a DMA scatterlist.

Project: linux
File: ccm.c

static int cbcmac_create(struct crypto_template *tmpl, struct rtattr **tb)
{
	struct shash_instance *inst;
	struct crypto_alg *alg;
	int err;

	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH);
	if (err)
		return err;

	alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
				  CRYPTO_ALG_TYPE_MASK);
	if (IS_ERR(alg))
		return PTR_ERR(alg);

	inst = shash_alloc_instance("cbcmac", alg);
	err = PTR_ERR(inst);
	if (IS_ERR(inst))
		goto out_put_alg;

	err = crypto_init_spawn(shash_instance_ctx(inst), alg,
				shash_crypto_instance(inst),
				CRYPTO_ALG_TYPE_MASK);
	if (err)
		goto out_free_inst;

	inst->alg.base.cra_priority = alg->cra_priority;
	inst->alg.base.cra_blocksize = 1;

	inst->alg.digestsize = alg->cra_blocksize;
	inst->alg.descsize = ALIGN(sizeof(struct cbcmac_desc_ctx),
				   alg->cra_alignmask + 1) +
			     alg->cra_blocksize;

	inst->alg.base.cra_ctxsize = sizeof(struct cbcmac_tfm_ctx);
	inst->alg.base.cra_init = cbcmac_init_tfm;
	inst->alg.base.cra_exit = cbcmac_exit_tfm;

	inst->alg.init = crypto_cbcmac_digest_init;
	inst->alg.update = crypto_cbcmac_digest_update;
	inst->alg.final = crypto_cbcmac_digest_final;
	inst->alg.setkey = crypto_cbcmac_digest_setkey;

	err = shash_register_instance(tmpl, inst);

out_free_inst:
	if (err)
		shash_free_instance(shash_crypto_instance(inst));

out_put_alg:
	crypto_mod_put(alg);
	return err;
}

Project: linux
File: ccm.c

static void cbcmac_exit_tfm(struct crypto_tfm *tfm)
{
	struct cbcmac_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
	crypto_free_cipher(ctx->child);
}

Project: linux
File: ccm.c

static int crypto_cbcmac_digest_final(struct shash_desc *pdesc, u8 *out)
{
	struct crypto_shash *parent = pdesc->tfm;
	struct cbcmac_tfm_ctx *tctx = crypto_shash_ctx(parent);
	struct cbcmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
	struct crypto_cipher *tfm = tctx->child;
	int bs = crypto_shash_digestsize(parent);
	u8 *dg = (u8 *)ctx + crypto_shash_descsize(parent) - bs;

	if (ctx->len)
		crypto_cipher_encrypt_one(tfm, dg, dg);

	memcpy(out, dg, bs);
	return 0;
}

Project: linux
File: ccm.c

static int crypto_cbcmac_digest_init(struct shash_desc *pdesc)
{
	struct cbcmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
	int bs = crypto_shash_digestsize(pdesc->tfm);
	u8 *dg = (u8 *)ctx + crypto_shash_descsize(pdesc->tfm) - bs;

	ctx->len = 0;
	memset(dg, 0, bs);

	return 0;
}

Project: linux
File: ccm.c

static int crypto_cbcmac_digest_setkey(struct crypto_shash *parent,
				     const u8 *inkey, unsigned int keylen)
{
	struct cbcmac_tfm_ctx *ctx = crypto_shash_ctx(parent);

	return crypto_cipher_setkey(ctx->child, inkey, keylen);
}

Project: linux
File: ccm.c

static int crypto_cbcmac_digest_update(struct shash_desc *pdesc, const u8 *p,
				       unsigned int len)
{
	struct crypto_shash *parent = pdesc->tfm;
	struct cbcmac_tfm_ctx *tctx = crypto_shash_ctx(parent);
	struct cbcmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
	struct crypto_cipher *tfm = tctx->child;
	int bs = crypto_shash_digestsize(parent);
	u8 *dg = (u8 *)ctx + crypto_shash_descsize(parent) - bs;

	while (len > 0) {
		unsigned int l = min(len, bs - ctx->len);

		crypto_xor(dg + ctx->len, p, l);
		ctx->len +=l;
		len -= l;
		p += l;

		if (ctx->len == bs) {
			crypto_cipher_encrypt_one(tfm, dg, dg);
			ctx->len = 0;
		}
	}

	return 0;
}

Project: linux
File: ccm.c

static int crypto_ccm_base_create(struct crypto_template *tmpl,
				  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 PTR_ERR(ctr_name);

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

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

	return crypto_ccm_create_common(tmpl, tb, full_name, ctr_name,
					cipher_name);
}

Project: linux
File: ccm.c

static int crypto_ccm_create(struct crypto_template *tmpl, struct rtattr **tb)
{
	const char *cipher_name;
	char ctr_name[CRYPTO_MAX_ALG_NAME];
	char mac_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 PTR_ERR(cipher_name);

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

	if (snprintf(mac_name, CRYPTO_MAX_ALG_NAME, "cbcmac(%s)",
		     cipher_name) >= CRYPTO_MAX_ALG_NAME)
		return -ENAMETOOLONG;

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

	return crypto_ccm_create_common(tmpl, tb, full_name, ctr_name,
					mac_name);
}

Project: linux
File: ccm.c

static int crypto_ccm_create_common(struct crypto_template *tmpl,
				    struct rtattr **tb,
				    const char *full_name,
				    const char *ctr_name,
				    const char *mac_name)
{
	struct crypto_attr_type *algt;
	struct aead_instance *inst;
	struct skcipher_alg *ctr;
	struct crypto_alg *mac_alg;
	struct hash_alg_common *mac;
	struct ccm_instance_ctx *ictx;
	int err;

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

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

	mac_alg = crypto_find_alg(mac_name, &crypto_ahash_type,
				  CRYPTO_ALG_TYPE_HASH,
				  CRYPTO_ALG_TYPE_AHASH_MASK |
				  CRYPTO_ALG_ASYNC);
	if (IS_ERR(mac_alg))
		return PTR_ERR(mac_alg);

	mac = __crypto_hash_alg_common(mac_alg);
	err = -EINVAL;
	if (mac->digestsize != 16)
		goto out_put_mac;

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

	ictx = aead_instance_ctx(inst);
	err = crypto_init_ahash_spawn(&ictx->mac, mac,
				      aead_crypto_instance(inst));
	if (err)
		goto err_free_inst;

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

	ctr = crypto_spawn_skcipher_alg(&ictx->ctr);

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

	/* We want the real thing! */
	if (crypto_skcipher_alg_ivsize(ctr) != 16)
		goto err_drop_ctr;

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

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

	inst->alg.base.cra_flags = ctr->base.cra_flags & CRYPTO_ALG_ASYNC;
	inst->alg.base.cra_priority = (mac->base.cra_priority +
				       ctr->base.cra_priority) / 2;
	inst->alg.base.cra_blocksize = 1;
	inst->alg.base.cra_alignmask = mac->base.cra_alignmask |
				       ctr->base.cra_alignmask;
	inst->alg.ivsize = 16;
	inst->alg.chunksize = crypto_skcipher_alg_chunksize(ctr);
	inst->alg.maxauthsize = 16;
	inst->alg.base.cra_ctxsize = sizeof(struct crypto_ccm_ctx);
	inst->alg.init = crypto_ccm_init_tfm;
	inst->alg.exit = crypto_ccm_exit_tfm;
	inst->alg.setkey = crypto_ccm_setkey;
	inst->alg.setauthsize = crypto_ccm_setauthsize;
	inst->alg.encrypt = crypto_ccm_encrypt;
	inst->alg.decrypt = crypto_ccm_decrypt;

	inst->free = crypto_ccm_free;

	err = aead_register_instance(tmpl, inst);
	if (err)
		goto err_drop_ctr;

out_put_mac:
	crypto_mod_put(mac_alg);
	return err;

err_drop_ctr:
	crypto_drop_skcipher(&ictx->ctr);
err_drop_mac:
	crypto_drop_ahash(&ictx->mac);
err_free_inst:
	kfree(inst);
	goto out_put_mac;
}

Project: linux
File: ccm.c

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 skcipher_request *skreq = &pctx->skreq;
	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;

	cryptlen -= authsize;

	err = crypto_ccm_init_crypt(req, authtag);
	if (err)
		return err;

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

	dst = pctx->src;
	if (req->src != req->dst)
		dst = pctx->dst;

	skcipher_request_set_tfm(skreq, ctx->ctr);
	skcipher_request_set_callback(skreq, pctx->flags,
				      crypto_ccm_decrypt_done, req);
	skcipher_request_set_crypt(skreq, pctx->src, dst, cryptlen + 16, iv);
	err = crypto_skcipher_decrypt(skreq);
	if (err)
		return err;

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

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

	return err;
}

Project: linux
File: ccm.c

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;
	struct scatterlist *dst;

	pctx->flags = 0;

	dst = sg_next(req->src == req->dst ? pctx->src : pctx->dst);

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

Project: linux
File: ccm.c

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 skcipher_request *skreq = &pctx->skreq;
	struct scatterlist *dst;
	unsigned int cryptlen = req->cryptlen;
	u8 *odata = pctx->odata;
	u8 *iv = req->iv;
	int err;

	err = crypto_ccm_init_crypt(req, odata);
	if (err)
		return err;

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

	dst = pctx->src;
	if (req->src != req->dst)
		dst = pctx->dst;

	skcipher_request_set_tfm(skreq, ctx->ctr);
	skcipher_request_set_callback(skreq, pctx->flags,
				      crypto_ccm_encrypt_done, req);
	skcipher_request_set_crypt(skreq, pctx->src, dst, cryptlen + 16, iv);
	err = crypto_skcipher_encrypt(skreq);
	if (err)
		return err;

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

Project: linux
File: ccm.c

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->assoclen + req->cryptlen,
					 crypto_aead_authsize(aead), 1);
	aead_request_complete(req, err);
}

Project: linux
File: ccm.c

static void crypto_ccm_exit_tfm(struct crypto_aead *tfm)
{
	struct crypto_ccm_ctx *ctx = crypto_aead_ctx(tfm);

	crypto_free_ahash(ctx->mac);
	crypto_free_skcipher(ctx->ctr);
}

Project: linux
File: ccm.c

static void crypto_ccm_free(struct aead_instance *inst)
{
	struct ccm_instance_ctx *ctx = aead_instance_ctx(inst);

	crypto_drop_ahash(&ctx->mac);
	crypto_drop_skcipher(&ctx->ctr);
	kfree(inst);
}

Project: linux
File: ccm.c

static int crypto_ccm_init_tfm(struct crypto_aead *tfm)
{
	struct aead_instance *inst = aead_alg_instance(tfm);
	struct ccm_instance_ctx *ictx = aead_instance_ctx(inst);
	struct crypto_ccm_ctx *ctx = crypto_aead_ctx(tfm);
	struct crypto_ahash *mac;
	struct crypto_skcipher *ctr;
	unsigned long align;
	int err;

	mac = crypto_spawn_ahash(&ictx->mac);
	if (IS_ERR(mac))
		return PTR_ERR(mac);

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

	ctx->mac = mac;
	ctx->ctr = ctr;

	align = crypto_aead_alignmask(tfm);
	align &= ~(crypto_tfm_ctx_alignment() - 1);
	crypto_aead_set_reqsize(
		tfm,
		align + sizeof(struct crypto_ccm_req_priv_ctx) +
		crypto_skcipher_reqsize(ctr));

	return 0;

err_free_mac:
	crypto_free_ahash(mac);
	return err;
}

Project: linux
File: ccm.c

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);
	crypto_unregister_template(&crypto_cbcmac_tmpl);
}

Project: linux
File: ccm.c

static int __init crypto_ccm_module_init(void)
{
	int err;

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

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

	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);
out_undo_cbcmac:
	crypto_register_template(&crypto_cbcmac_tmpl);
	goto out;
}

Project: linux
File: ccm.c

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 = 0;

	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);
	crypto_aead_set_flags(aead, crypto_skcipher_get_flags(ctr) &
			      CRYPTO_TFM_RES_MASK);
	if (err)
		goto out;

	crypto_ahash_clear_flags(mac, CRYPTO_TFM_REQ_MASK);
	crypto_ahash_set_flags(mac, crypto_aead_get_flags(aead) &
				    CRYPTO_TFM_REQ_MASK);
	err = crypto_ahash_setkey(mac, key, keylen);
	crypto_aead_set_flags(aead, crypto_ahash_get_flags(mac) &
			      CRYPTO_TFM_RES_MASK);

out:
	return err;
}

Project: linux
File: ccm.c

static int crypto_rfc4309_create(struct crypto_template *tmpl,
				 struct rtattr **tb)
{
	struct crypto_attr_type *algt;
	struct aead_instance *inst;
	struct crypto_aead_spawn *spawn;
	struct aead_alg *alg;
	const char *ccm_name;
	int err;

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

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

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

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

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

	alg = crypto_spawn_aead_alg(spawn);

	err = -EINVAL;

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

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

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

	inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC;
	inst->alg.base.cra_priority = alg->base.cra_priority;
	inst->alg.base.cra_blocksize = 1;
	inst->alg.base.cra_alignmask = alg->base.cra_alignmask;

	inst->alg.ivsize = 8;
	inst->alg.chunksize = crypto_aead_alg_chunksize(alg);
	inst->alg.maxauthsize = 16;

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

	inst->alg.init = crypto_rfc4309_init_tfm;
	inst->alg.exit = crypto_rfc4309_exit_tfm;

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

	inst->free = crypto_rfc4309_free;

	err = aead_register_instance(tmpl, inst);
	if (err)
		goto out_drop_alg;

out:
	return err;

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

Project: linux
File: ccm.c

static struct aead_request *crypto_rfc4309_crypt(struct aead_request *req)
{
	struct crypto_rfc4309_req_ctx *rctx = aead_request_ctx(req);
	struct aead_request *subreq = &rctx->subreq;
	struct crypto_aead *aead = crypto_aead_reqtfm(req);
	struct crypto_rfc4309_ctx *ctx = crypto_aead_ctx(aead);
	struct crypto_aead *child = ctx->child;
	struct scatterlist *sg;
	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);

	scatterwalk_map_and_copy(iv + 16, req->src, 0, req->assoclen - 8, 0);

	sg_init_table(rctx->src, 3);
	sg_set_buf(rctx->src, iv + 16, req->assoclen - 8);
	sg = scatterwalk_ffwd(rctx->src + 1, req->src, req->assoclen);
	if (sg != rctx->src + 1)
		sg_chain(rctx->src, 2, sg);

	if (req->src != req->dst) {
		sg_init_table(rctx->dst, 3);
		sg_set_buf(rctx->dst, iv + 16, req->assoclen - 8);
		sg = scatterwalk_ffwd(rctx->dst + 1, req->dst, req->assoclen);
		if (sg != rctx->dst + 1)
			sg_chain(rctx->dst, 2, sg);
	}

	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, rctx->src,
			       req->src == req->dst ? rctx->src : rctx->dst,
			       req->cryptlen, iv);
	aead_request_set_ad(subreq, req->assoclen - 8);

	return subreq;
}

Project: linux
File: ccm.c

static int crypto_rfc4309_decrypt(struct aead_request *req)
{
	if (req->assoclen != 16 && req->assoclen != 20)
		return -EINVAL;

	req = crypto_rfc4309_crypt(req);

	return crypto_aead_decrypt(req);
}

Project: linux
File: ccm.c

static int crypto_rfc4309_encrypt(struct aead_request *req)
{
	if (req->assoclen != 16 && req->assoclen != 20)
		return -EINVAL;

	req = crypto_rfc4309_crypt(req);

	return crypto_aead_encrypt(req);
}

Project: linux
File: ccm.c

static void crypto_rfc4309_exit_tfm(struct crypto_aead *tfm)
{
	struct crypto_rfc4309_ctx *ctx = crypto_aead_ctx(tfm);

	crypto_free_aead(ctx->child);
}

Project: linux
File: ccm.c

static void crypto_rfc4309_free(struct aead_instance *inst)
{
	crypto_drop_aead(aead_instance_ctx(inst));
	kfree(inst);
}

Project: linux
File: ccm.c

static int crypto_rfc4309_init_tfm(struct crypto_aead *tfm)
{
	struct aead_instance *inst = aead_alg_instance(tfm);
	struct crypto_aead_spawn *spawn = aead_instance_ctx(inst);
	struct crypto_rfc4309_ctx *ctx = crypto_aead_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);
	crypto_aead_set_reqsize(
		tfm,
		sizeof(struct crypto_rfc4309_req_ctx) +
		ALIGN(crypto_aead_reqsize(aead), crypto_tfm_ctx_alignment()) +
		align + 32);

	return 0;
}