HMAC算法模板實例

• HMAC算法模板的創建實例的接口是hmac_create函數
• hmac.c - crypto/hmac.c - Linux source code (v5.15.11) - Bootlin? hmac_create
• 輸入的參數包括? 算法模板 tmpl? 和? 算法模板實例參數? tb
• hmac_cretae函數返回的結果為0表示算法模板實例已經創建注冊
• 算法模板 tmpl

struct crypto_template {struct list_head list;struct hlist_head instances;struct module *module;int (*create)(struct crypto_template *tmpl, struct rtattr **tb);char name[CRYPTO_MAX_ALG_NAME];
};

• 算法模板實例參數? tb 顯示如下

struct rtattr {unsigned short	rta_len;unsigned short	rta_type;
};

• ?hmac_cretae函數顯示如下

static int hmac_create(struct crypto_template *tmpl, struct rtattr **tb)
{struct shash_instance *inst;struct crypto_shash_spawn *spawn;struct crypto_alg *alg;struct shash_alg *salg;u32 mask;int err;int ds;int ss;err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH, &mask);if (err)return err;inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);if (!inst)return -ENOMEM;spawn = shash_instance_ctx(inst);err = crypto_grab_shash(spawn, shash_crypto_instance(inst),crypto_attr_alg_name(tb[1]), 0, mask);if (err)goto err_free_inst;salg = crypto_spawn_shash_alg(spawn);alg = &salg->base;/* The underlying hash algorithm must not require a key */err = -EINVAL;if (crypto_shash_alg_needs_key(salg))goto err_free_inst;ds = salg->digestsize;ss = salg->statesize;if (ds > alg->cra_blocksize ||ss < alg->cra_blocksize)goto err_free_inst;err = crypto_inst_setname(shash_crypto_instance(inst), tmpl->name, alg);if (err)goto err_free_inst;inst->alg.base.cra_priority = alg->cra_priority;inst->alg.base.cra_blocksize = alg->cra_blocksize;inst->alg.base.cra_alignmask = alg->cra_alignmask;ss = ALIGN(ss, alg->cra_alignmask + 1);inst->alg.digestsize = ds;inst->alg.statesize = ss;inst->alg.base.cra_ctxsize = sizeof(struct hmac_ctx) +ALIGN(ss * 2, crypto_tfm_ctx_alignment());inst->alg.init = hmac_init;inst->alg.update = hmac_update;inst->alg.final = hmac_final;inst->alg.finup = hmac_finup;inst->alg.export = hmac_export;inst->alg.import = hmac_import;inst->alg.setkey = hmac_setkey;inst->alg.init_tfm = hmac_init_tfm;inst->alg.exit_tfm = hmac_exit_tfm;inst->free = shash_free_singlespawn_instance;err = shash_register_instance(tmpl, inst);if (err) {
err_free_inst:shash_free_singlespawn_instance(inst);}return err;
}

hmac_create函數創建并且注冊的流程如下圖所示?

hmac_create函數的調用流程?

?

參考鏈接

• ?Linux加密框架中的主要數據結構（四）_家有一希的博客-CSDN博客