+static int n2_hmac_cra_init(struct crypto_tfm *tfm)
+{
+ const char *fallback_driver_name = tfm->__crt_alg->cra_name;
+ struct crypto_ahash *ahash = __crypto_ahash_cast(tfm);
+ struct n2_hmac_ctx *ctx = crypto_ahash_ctx(ahash);
+ struct n2_hmac_alg *n2alg = n2_hmac_alg(tfm);
+ struct crypto_ahash *fallback_tfm;
+ struct crypto_shash *child_shash;
+ int err;
+
+ fallback_tfm = crypto_alloc_ahash(fallback_driver_name, 0,
+ CRYPTO_ALG_NEED_FALLBACK);
+ if (IS_ERR(fallback_tfm)) {
+ pr_warning("Fallback driver '%s' could not be loaded!\n",
+ fallback_driver_name);
+ err = PTR_ERR(fallback_tfm);
+ goto out;
+ }
+
+ child_shash = crypto_alloc_shash(n2alg->child_alg, 0, 0);
+ if (IS_ERR(child_shash)) {
+ pr_warning("Child shash '%s' could not be loaded!\n",
+ n2alg->child_alg);
+ err = PTR_ERR(child_shash);
+ goto out_free_fallback;
+ }
+
+ crypto_ahash_set_reqsize(ahash, (sizeof(struct n2_hash_req_ctx) +
+ crypto_ahash_reqsize(fallback_tfm)));
+
+ ctx->child_shash = child_shash;
+ ctx->base.fallback_tfm = fallback_tfm;
+ return 0;
+
+out_free_fallback:
+ crypto_free_ahash(fallback_tfm);
+
+out:
+ return err;
+}
+
+static void n2_hmac_cra_exit(struct crypto_tfm *tfm)
+{
+ struct crypto_ahash *ahash = __crypto_ahash_cast(tfm);
+ struct n2_hmac_ctx *ctx = crypto_ahash_ctx(ahash);
+
+ crypto_free_ahash(ctx->base.fallback_tfm);
+ crypto_free_shash(ctx->child_shash);
+}
+
+static int n2_hmac_async_setkey(struct crypto_ahash *tfm, const u8 *key,
+ unsigned int keylen)
+{
+ struct n2_hmac_ctx *ctx = crypto_ahash_ctx(tfm);
+ struct crypto_shash *child_shash = ctx->child_shash;
+ struct crypto_ahash *fallback_tfm;
+ struct {
+ struct shash_desc shash;
+ char ctx[crypto_shash_descsize(child_shash)];
+ } desc;
+ int err, bs, ds;
+
+ fallback_tfm = ctx->base.fallback_tfm;
+ err = crypto_ahash_setkey(fallback_tfm, key, keylen);
+ if (err)
+ return err;
+
+ desc.shash.tfm = child_shash;
+ desc.shash.flags = crypto_ahash_get_flags(tfm) &
+ CRYPTO_TFM_REQ_MAY_SLEEP;
+
+ bs = crypto_shash_blocksize(child_shash);
+ ds = crypto_shash_digestsize(child_shash);
+ BUG_ON(ds > N2_HASH_KEY_MAX);
+ if (keylen > bs) {
+ err = crypto_shash_digest(&desc.shash, key, keylen,
+ ctx->hash_key);
+ if (err)
+ return err;
+ keylen = ds;
+ } else if (keylen <= N2_HASH_KEY_MAX)
+ memcpy(ctx->hash_key, key, keylen);
+
+ ctx->hash_key_len = keylen;
+
+ return err;
+}
+