[CRYPTO] gcm: Allow block cipher parameter

This patch adds the gcm_base template which takes a block cipher
parameter instead of cipher. This allows the user to specify a
specific CTR implementation.

This also fixes a leak of the cipher algorithm that was previously
looked up but never freed.

Signed-off-by: Herbert Xu <[e-mail]>

crypto/gcm.c

···
 	crypto_free_ablkcipher(ctx->ctr);
 }
 
-static struct crypto_instance *crypto_gcm_alloc(struct rtattr **tb)
+static struct crypto_instance *crypto_gcm_alloc_common(struct rtattr **tb,
+						       const char *full_name,
+						       const char *ctr_name)
 {
+	struct crypto_attr_type *algt;
 	struct crypto_instance *inst;
 	struct crypto_alg *ctr;
-	struct crypto_alg *cipher;
 	struct gcm_instance_ctx *ctx;
 	int err;
-	char ctr_name[CRYPTO_MAX_ALG_NAME];
 
-	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_AEAD);
-	if (err)
+	algt = crypto_get_attr_type(tb);
+	err = PTR_ERR(algt);
+	if (IS_ERR(algt))
 		return ERR_PTR(err);
 
-	cipher = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER,
-			      CRYPTO_ALG_TYPE_MASK);
-
-	inst = ERR_PTR(PTR_ERR(cipher));
-	if (IS_ERR(cipher))
-		return inst;
-
-	inst = ERR_PTR(ENAMETOOLONG);
-	if (snprintf(ctr_name, CRYPTO_MAX_ALG_NAME, "ctr(%s)",
-		     cipher->cra_name) >= CRYPTO_MAX_ALG_NAME)
-		return inst;
+	if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
+		return ERR_PTR(-EINVAL);
 
 	ctr = crypto_alg_mod_lookup(ctr_name, CRYPTO_ALG_TYPE_BLKCIPHER,
 				    CRYPTO_ALG_TYPE_MASK);
···
 	if (IS_ERR(ctr))
 		return ERR_PTR(PTR_ERR(ctr));
 
-	if (cipher->cra_blocksize != 16)
+	/* We only support 16-byte blocks. */
+	if ((ctr->cra_type == &crypto_blkcipher_type ?
+	     ctr->cra_blkcipher.ivsize : ctr->cra_ablkcipher.ivsize) != 16)
+		goto out_put_ctr;
+
+	/* Not a stream cipher? */
+	err = -EINVAL;
+	if (ctr->cra_blocksize != 1)
 		goto out_put_ctr;
 
 	inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
···
 		goto out_put_ctr;
 
 	err = -ENAMETOOLONG;
-	if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME,
-		     "gcm(%s)", cipher->cra_name) >= CRYPTO_MAX_ALG_NAME ||
-	    snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
-		     "gcm(%s)", cipher->cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
+	if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
+		     "gcm_base(%s)", ctr->cra_driver_name) >=
+	    CRYPTO_MAX_ALG_NAME)
 		goto err_free_inst;
-
 
 	ctx = crypto_instance_ctx(inst);
 	err = crypto_init_spawn(&ctx->ctr, ctr, inst, CRYPTO_ALG_TYPE_MASK);
 	if (err)
 		goto err_free_inst;
 
+	memcpy(inst->alg.cra_name, full_name, CRYPTO_MAX_ALG_NAME);
+
 	inst->alg.cra_flags = CRYPTO_ALG_TYPE_AEAD | CRYPTO_ALG_ASYNC;
 	inst->alg.cra_priority = ctr->cra_priority;
-	inst->alg.cra_blocksize = 16;
+	inst->alg.cra_blocksize = 1;
 	inst->alg.cra_alignmask = ctr->cra_alignmask | (__alignof__(u64) - 1);
 	inst->alg.cra_type = &crypto_aead_type;
 	inst->alg.cra_aead.ivsize = 16;
···
 	goto out;
 }
 
+static struct crypto_instance *crypto_gcm_alloc(struct rtattr **tb)
+{
+	int err;
+	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]);
+	err = PTR_ERR(cipher_name);
+	if (IS_ERR(cipher_name))
+		return ERR_PTR(err);
+
+	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, "gcm(%s)", cipher_name) >=
+	    CRYPTO_MAX_ALG_NAME)
+		return ERR_PTR(-ENAMETOOLONG);
+
+	return crypto_gcm_alloc_common(tb, full_name, ctr_name);
+}
+
 static void crypto_gcm_free(struct crypto_instance *inst)
 {
 	struct gcm_instance_ctx *ctx = crypto_instance_ctx(inst);
···
 	.module = THIS_MODULE,
 };
 
+static struct crypto_instance *crypto_gcm_base_alloc(struct rtattr **tb)
+{
+	int err;
+	const char *ctr_name;
+	char full_name[CRYPTO_MAX_ALG_NAME];
+
+	ctr_name = crypto_attr_alg_name(tb[1]);
+	err = PTR_ERR(ctr_name);
+	if (IS_ERR(ctr_name))
+		return ERR_PTR(err);
+
+	if (snprintf(full_name, CRYPTO_MAX_ALG_NAME, "gcm_base(%s)",
+		     ctr_name) >= CRYPTO_MAX_ALG_NAME)
+		return ERR_PTR(-ENAMETOOLONG);
+
+	return crypto_gcm_alloc_common(tb, full_name, ctr_name);
+}
+
+static struct crypto_template crypto_gcm_base_tmpl = {
+	.name = "gcm_base",
+	.alloc = crypto_gcm_base_alloc,
+	.free = crypto_gcm_free,
+	.module = THIS_MODULE,
+};
+
 static int __init crypto_gcm_module_init(void)
 {
-	return crypto_register_template(&crypto_gcm_tmpl);
+	int err;
+
+	err = crypto_register_template(&crypto_gcm_base_tmpl);
+	if (err)
+		goto out;
+
+	err = crypto_register_template(&crypto_gcm_tmpl);
+	if (err)
+		goto out_undo_base;
+
+out:
+	return err;
+
+out_undo_base:
+	crypto_unregister_template(&crypto_gcm_base_tmpl);
+	goto out;
 }
 
 static void __exit crypto_gcm_module_exit(void)
 {
 	crypto_unregister_template(&crypto_gcm_tmpl);
+	crypto_unregister_template(&crypto_gcm_base_tmpl);
 }
 
 module_init(crypto_gcm_module_init);
···
 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("Galois/Counter Mode");
 MODULE_AUTHOR("Mikko Herranen <[e-mail]>");
+MODULE_ALIAS("gcm_base");