[CRYPTO] gcm: Introduce rfc4106

This patch introduces the rfc4106 wrapper for GCM just as we have an
rfc4309 wrapper for CCM.  The purpose of the wrapper is to include part
of the IV in the key so that it can be negotiated by IPsec.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/gcm.c

@@ -9,6 +9,7 @@
  */
 
 #include <crypto/gf128mul.h>
+#include <crypto/internal/aead.h>
 #include <crypto/internal/skcipher.h>
 #include <crypto/scatterwalk.h>
 #include <linux/completion.h>
@@ -27,6 +28,11 @@ struct crypto_gcm_ctx {
 	struct gf128mul_4k *gf128;
 };
 
+struct crypto_rfc4106_ctx {
+	struct crypto_aead *child;
+	u8 nonce[4];
+};
+
 struct crypto_gcm_ghash_ctx {
 	u32 bytes;
 	u32 flags;
@@ -240,6 +246,25 @@ static int crypto_gcm_setkey(struct crypto_aead *aead, const u8 *key,
 	return err;
 }
 
+static int crypto_gcm_setauthsize(struct crypto_aead *tfm,
+				  unsigned int authsize)
+{
+	switch (authsize) {
+	case 4:
+	case 8:
+	case 12:
+	case 13:
+	case 14:
+	case 15:
+	case 16:
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 static void crypto_gcm_init_crypt(struct ablkcipher_request *ablk_req,
 				  struct aead_request *req,
 				  unsigned int cryptlen)
@@ -472,6 +497,7 @@ static struct crypto_instance *crypto_gcm_alloc_common(struct rtattr **tb,
 	inst->alg.cra_init = crypto_gcm_init_tfm;
 	inst->alg.cra_exit = crypto_gcm_exit_tfm;
 	inst->alg.cra_aead.setkey = crypto_gcm_setkey;
+	inst->alg.cra_aead.setauthsize = crypto_gcm_setauthsize;
 	inst->alg.cra_aead.encrypt = crypto_gcm_encrypt;
 	inst->alg.cra_aead.decrypt = crypto_gcm_decrypt;
 
@@ -549,6 +575,211 @@ static struct crypto_template crypto_gcm_base_tmpl = {
 	.module = THIS_MODULE,
 };
 
+static int crypto_rfc4106_setkey(struct crypto_aead *parent, const u8 *key,
+				 unsigned int keylen)
+{
+	struct crypto_rfc4106_ctx *ctx = crypto_aead_ctx(parent);
+	struct crypto_aead *child = ctx->child;
+	int err;
+
+	if (keylen < 4)
+		return -EINVAL;
+
+	keylen -= 4;
+	memcpy(ctx->nonce, key + keylen, 4);
+
+	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_rfc4106_setauthsize(struct crypto_aead *parent,
+				      unsigned int authsize)
+{
+	struct crypto_rfc4106_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_rfc4106_crypt(struct aead_request *req)
+{
+	struct aead_request *subreq = aead_request_ctx(req);
+	struct crypto_aead *aead = crypto_aead_reqtfm(req);
+	struct crypto_rfc4106_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);
+
+	memcpy(iv, ctx->nonce, 4);
+	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_rfc4106_encrypt(struct aead_request *req)
+{
+	req = crypto_rfc4106_crypt(req);
+
+	return crypto_aead_encrypt(req);
+}
+
+static int crypto_rfc4106_decrypt(struct aead_request *req)
+{
+	req = crypto_rfc4106_crypt(req);
+
+	return crypto_aead_decrypt(req);
+}
+
+static int crypto_rfc4106_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_rfc4106_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_rfc4106_exit_tfm(struct crypto_tfm *tfm)
+{
+	struct crypto_rfc4106_ctx *ctx = crypto_tfm_ctx(tfm);
+
+	crypto_free_aead(ctx->child);
+}
+
+static struct crypto_instance *crypto_rfc4106_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);
+	err = PTR_ERR(algt);
+	if (IS_ERR(algt))
+		return ERR_PTR(err);
+
+	if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
+		return ERR_PTR(-EINVAL);
+
+	ccm_name = crypto_attr_alg_name(tb[1]);
+	err = PTR_ERR(ccm_name);
+	if (IS_ERR(ccm_name))
+		return ERR_PTR(err);
+
+	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,
+		     "rfc4106(%s)", alg->cra_name) >= CRYPTO_MAX_ALG_NAME ||
+	    snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
+		     "rfc4106(%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_rfc4106_ctx);
+
+	inst->alg.cra_init = crypto_rfc4106_init_tfm;
+	inst->alg.cra_exit = crypto_rfc4106_exit_tfm;
+
+	inst->alg.cra_aead.setkey = crypto_rfc4106_setkey;
+	inst->alg.cra_aead.setauthsize = crypto_rfc4106_setauthsize;
+	inst->alg.cra_aead.encrypt = crypto_rfc4106_encrypt;
+	inst->alg.cra_aead.decrypt = crypto_rfc4106_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_rfc4106_free(struct crypto_instance *inst)
+{
+	crypto_drop_spawn(crypto_instance_ctx(inst));
+	kfree(inst);
+}
+
+static struct crypto_template crypto_rfc4106_tmpl = {
+	.name = "rfc4106",
+	.alloc = crypto_rfc4106_alloc,
+	.free = crypto_rfc4106_free,
+	.module = THIS_MODULE,
+};
+
 static int __init crypto_gcm_module_init(void)
 {
 	int err;
@@ -561,9 +792,15 @@ static int __init crypto_gcm_module_init(void)
 	if (err)
 		goto out_undo_base;
 
+	err = crypto_register_template(&crypto_rfc4106_tmpl);
+	if (err)
+		goto out_undo_gcm;
+
 out:
 	return err;
 
+out_undo_gcm:
+	crypto_unregister_template(&crypto_gcm_tmpl);
 out_undo_base:
 	crypto_unregister_template(&crypto_gcm_base_tmpl);
 	goto out;
@@ -571,6 +808,7 @@ static int __init crypto_gcm_module_init(void)
 
 static void __exit crypto_gcm_module_exit(void)
 {
+	crypto_unregister_template(&crypto_rfc4106_tmpl);
 	crypto_unregister_template(&crypto_gcm_tmpl);
 	crypto_unregister_template(&crypto_gcm_base_tmpl);
 }
@@ -582,3 +820,4 @@ MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("Galois/Counter Mode");
 MODULE_AUTHOR("Mikko Herranen <mh1@iki.fi>");
 MODULE_ALIAS("gcm_base");
+MODULE_ALIAS("rfc4106");