參考鏈接
- Linux加密框架的算法管理（四）_家有一希的博客-CSDN博客
函數介紹
- 如前所述，無論是靜態算法還是動態算法，算法注冊的最后一步都是進行算法正確性檢驗，一般流程是先調用__crypto_register_alg函數進行通用的算法注冊（即將待注冊的算法添加到算法管理鏈表中），同時創建對應的檢測用算法幼蟲，然后調用crypto_wait_for_test函數啟動算法正確性檢驗，并等待檢驗結束。
- 簡單地說，算法正確性檢驗就是利用樣本數據sampledata對算法接口進行計算正確性的驗證。算法通過正確性檢驗的標志是算法標志cra_flags中置算法已檢測標志CRYPTO_ALG_TESTED。算法通過正確性檢驗說明能夠提供正常的服務，如加密/解密服務、計算消息摘要服務等。
- crypto_wait_for_test函數用于啟動算法正確性檢驗，并等待檢驗結束，輸入參數為檢測用算法幼蟲larval
- 函數處理流程如下所示。
static void crypto_wait_for_test(struct crypto_larval *larval)
{int err;err = crypto_probing_notify(CRYPTO_MSG_ALG_REGISTER, larval->adult);if (err != NOTIFY_STOP) {if (WARN_ON(err != NOTIFY_DONE))goto out;crypto_alg_tested(larval->alg.cra_driver_name, 0);}err = wait_for_completion_killable(&larval->completion);WARN_ON(err);if (!err)crypto_notify(CRYPTO_MSG_ALG_LOADED, larval);out:crypto_larval_kill(&larval->alg);
}
- 1)在crypto_wait_for_test函數中，調用crypto_probing_notify函數在加密通知鏈上發布算法正確性檢驗（CRYPTO_MSG_ALG_REGISTER）的通知，攜帶的參數為檢測用算法幼蟲對應的算法成蟲，即待檢驗的算法。
- 2)靜態算法（如AES算法）注冊發布算法檢驗通知時，算法管理鏈表如下所示，其中aes_larval_t表示檢測用算法幼蟲，關聯到對應的算法成蟲（aes_larval_t->adult=aes_alg）。?
- 3)動態算法（如"cbc(aes)"算法）注冊發布算法檢驗通知時，算法管理鏈表如下所示，其中cbc_aes_larval_r表示注冊用算法幼蟲，cbc_aes_larval_t表示檢測用算法幼蟲，注冊用算法幼蟲還未關聯到算法成蟲，檢測用算法幼蟲關聯到算法成蟲（cbc_aes_larval_t->adult=cbc_aes_alg）。?
算法檢測啟動
- 發布算法檢測通知后，加密通知鏈回調函數cryptomgr_notify（CRYPTO_MSG_ALG_REGISTER）將調用cryptomgr_schedule_test函數啟動算法檢測。
- algboss.c - crypto/algboss.c - Linux source code (v5.15.12) - Bootlin
static int cryptomgr_notify(struct notifier_block *this, unsigned long msg,void *data)
{switch (msg) {case CRYPTO_MSG_ALG_REQUEST:return cryptomgr_schedule_probe(data);case CRYPTO_MSG_ALG_REGISTER:return cryptomgr_schedule_test(data);case CRYPTO_MSG_ALG_LOADED:break;}return NOTIFY_DONE;
}
- algboss.c - crypto/algboss.c - Linux source code (v5.15.12) - Bootlin
static int cryptomgr_schedule_test(struct crypto_alg *alg)
{struct task_struct *thread;struct crypto_test_param *param;u32 type;if (!try_module_get(THIS_MODULE))goto err;param = kzalloc(sizeof(*param), GFP_KERNEL);if (!param)goto err_put_module;memcpy(param->driver, alg->cra_driver_name, sizeof(param->driver));memcpy(param->alg, alg->cra_name, sizeof(param->alg));type = alg->cra_flags;/* Do not test internal algorithms. */if (type & CRYPTO_ALG_INTERNAL)type |= CRYPTO_ALG_TESTED;param->type = type;thread = kthread_run(cryptomgr_test, param, "cryptomgr_test");if (IS_ERR(thread))goto err_free_param;return NOTIFY_STOP;err_free_param:kfree(param);
err_put_module:module_put(THIS_MODULE);
err:return NOTIFY_OK;
}
- cryptomgr_schedule_test函數輸入參數為待檢測的算法alg，通過創建專門的算法檢測線程處理算法正確性檢驗
- 處理流程如下所示
- ?1)算法正確性檢驗的參數數據結構為struct crypto_test_param，定義如下所示。
- algboss.c - crypto/algboss.c - Linux source code (v5.15.12) - Bootlin
struct crypto_test_param {char driver[CRYPTO_MAX_ALG_NAME];char alg[CRYPTO_MAX_ALG_NAME];u32 type;
};
參數介紹
- 如上所示，算法正確性檢驗的參數包括算法驅動名driver、算法名alg和算法類型type。
- 2)cryptomgr_schedule_test函數將創建名為"cryptomgr_test"的內核線程（即算法檢驗線程）處理算法正確性檢驗，處理接口為cryptomgr_test。
thread = kthread_run(cryptomgr_test, param, "cryptomgr_test");if (IS_ERR(thread))goto err_free_param;return NOTIFY_STOP;
- 3)在cryptomgr_test函數中，調用alg_test函數根據算法驅動名driver、算法名alg和算法類型type實現算法正確性檢驗。
- err = alg_test(param->driver, param->alg, type, CRYPTO_ALG_TESTED);
static int cryptomgr_test(void *data)
{struct crypto_test_param *param = data;u32 type = param->type;int err = 0;#ifdef CONFIG_CRYPTO_MANAGER_DISABLE_TESTSgoto skiptest;
#endifif (type & CRYPTO_ALG_TESTED)goto skiptest;err = alg_test(param->driver, param->alg, type, CRYPTO_ALG_TESTED);skiptest:crypto_alg_tested(param->driver, err);kfree(param);module_put_and_exit(0);
}static int cryptomgr_schedule_test(struct crypto_alg *alg)
{struct task_struct *thread;struct crypto_test_param *param;u32 type;if (!try_module_get(THIS_MODULE))goto err;param = kzalloc(sizeof(*param), GFP_KERNEL);if (!param)goto err_put_module;memcpy(param->driver, alg->cra_driver_name, sizeof(param->driver));memcpy(param->alg, alg->cra_name, sizeof(param->alg));type = alg->cra_flags;/* Do not test internal algorithms. */if (type & CRYPTO_ALG_INTERNAL)type |= CRYPTO_ALG_TESTED;param->type = type;thread = kthread_run(cryptomgr_test, param, "cryptomgr_test");if (IS_ERR(thread))goto err_free_param;return NOTIFY_STOP;err_free_param:kfree(param);
err_put_module:module_put(THIS_MODULE);
err:return NOTIFY_OK;
}
算法檢測結束
- 在cryptomgr_test函數中，算法正確性檢驗結束后將調用crypto_alg_tested函數完成收尾工作。
- algapi.c - crypto/algapi.c - Linux source code (v5.15.12) - Bootlin
void crypto_alg_tested(const char *name, int err)
{struct crypto_larval *test;struct crypto_alg *alg;struct crypto_alg *q;LIST_HEAD(list);bool best;down_write(&crypto_alg_sem);list_for_each_entry(q, &crypto_alg_list, cra_list) {if (crypto_is_moribund(q) || !crypto_is_larval(q))continue;test = (struct crypto_larval *)q;if (!strcmp(q->cra_driver_name, name))goto found;}pr_err("alg: Unexpected test result for %s: %d\n", name, err);goto unlock;found:q->cra_flags |= CRYPTO_ALG_DEAD;alg = test->adult;if (err || list_empty(&alg->cra_list))goto complete;alg->cra_flags |= CRYPTO_ALG_TESTED;/* Only satisfy larval waiters if we are the best. */best = true;list_for_each_entry(q, &crypto_alg_list, cra_list) {if (crypto_is_moribund(q) || !crypto_is_larval(q))continue;if (strcmp(alg->cra_name, q->cra_name))continue;if (q->cra_priority > alg->cra_priority) {best = false;break;}}list_for_each_entry(q, &crypto_alg_list, cra_list) {if (q == alg)continue;if (crypto_is_moribund(q))continue;if (crypto_is_larval(q)) {struct crypto_larval *larval = (void *)q;/** Check to see if either our generic name or* specific name can satisfy the name requested* by the larval entry q.*/if (strcmp(alg->cra_name, q->cra_name) &&strcmp(alg->cra_driver_name, q->cra_name))continue;if (larval->adult)continue;if ((q->cra_flags ^ alg->cra_flags) & larval->mask)continue;if (best && crypto_mod_get(alg))larval->adult = alg;elselarval->adult = ERR_PTR(-EAGAIN);continue;}if (strcmp(alg->cra_name, q->cra_name))continue;if (strcmp(alg->cra_driver_name, q->cra_driver_name) &&q->cra_priority > alg->cra_priority)continue;crypto_remove_spawns(q, &list, alg);}complete:complete_all(&test->completion);unlock:up_write(&crypto_alg_sem);crypto_remove_final(&list);
}
EXPORT_SYMBOL_GPL(crypto_alg_tested);
- crypto_alg_tested函數輸入參數包括算法驅動名name和檢驗結果err（為0表示檢驗正確，非0表示檢驗失敗），處理流程如下所示。
- 1)檢測結束收尾時，需要通過算法幼蟲的完成量喚醒等待注冊、檢驗結束的線程。
- 在crypto_alg_tested函數中，首先根據輸入的算法驅動名name查找對應的檢測用算法幼蟲test，如下所示。
test = (struct crypto_larval *)q;if (!strcmp(q->cra_driver_name, name))goto found;
- 然后根據檢測用算法幼蟲test關聯到算法成蟲alg，如果算法檢測通過（err=0）則設置算法成功alg的已檢驗標志 CRYPTO_ALG_TESTED，同時將檢測用算法幼蟲設置為已死亡，表示檢測用算法幼蟲的使命終結，如下所示。
found:q->cra_flags |= CRYPTO_ALG_DEAD;alg = test->adult;if (err || list_empty(&alg->cra_list))goto complete;alg->cra_flags |= CRYPTO_ALG_TESTED;
- 注意：算法檢驗收尾時，只是通過注冊用和檢驗用算法幼蟲喚醒等待算法注冊完成的線程，并不清理注冊過程中的中間變量（即注冊用和檢驗用算法幼蟲）?
?
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