efuse(esp32): Deprecate esp_efuse_burn_new_values() & esp_efuse_write_random_key()

These functions were used only for esp32 in secure_boot and flash encryption.
Use idf efuse APIs instead of efuse regs.

components/bootloader_support/src/secure_boot_v2/secure_boot.c

@@ -0,0 +1,325 @@
+/*
+ * SPDX-FileCopyrightText: 2015-2021 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <string.h>
+#include "sdkconfig.h"
+#include "esp_log.h"
+#include "esp_secure_boot.h"
+#include "bootloader_flash_priv.h"
+#include "bootloader_sha.h"
+#include "bootloader_utility.h"
+#include "esp_image_format.h"
+#include "esp_efuse.h"
+#include "esp_efuse_table.h"
+
+/* The following API implementations are used only when called
+ * from the bootloader code.
+ */
+
+#ifdef CONFIG_SECURE_BOOT_V2_ENABLED
+
+#define ALIGN_UP(num, align) (((num) + ((align) - 1)) & ~((align) - 1))
+static const char *TAG = "secure_boot_v2";
+
+/* A signature block is valid when it has correct magic byte, crc and image digest. */
+static esp_err_t validate_signature_block(const ets_secure_boot_sig_block_t *block, int block_num, const uint8_t *image_digest)
+{
+    if (block->magic_byte != ETS_SECURE_BOOT_V2_SIGNATURE_MAGIC) {
+        // All signature blocks have been parsed, no new signature block present.
+        ESP_LOGD(TAG, "Signature block(%d) invalid/absent.", block_num);
+        return ESP_FAIL;
+    }
+    if (block->block_crc != esp_rom_crc32_le(0, (uint8_t *)block, CRC_SIGN_BLOCK_LEN)) {
+        ESP_LOGE(TAG, "Magic byte correct but incorrect crc.");
+        return ESP_FAIL;
+    }
+    if (memcmp(image_digest, block->image_digest, ESP_SECURE_BOOT_DIGEST_LEN)) {
+        ESP_LOGE(TAG, "Magic byte & CRC correct but incorrect image digest.");
+        return ESP_FAIL;
+    } else {
+        ESP_LOGD(TAG, "valid signature block(%d) found", block_num);
+        return ESP_OK;
+    }
+    return ESP_FAIL;
+}
+
+/* Generates the public key digests of the valid public keys in an image's
+   signature block, verifies each signature, and stores the key digests in the
+   public_key_digests structure.
+
+   @param flash_offset Image offset in flash
+   @param flash_size Image size in flash (not including signature block)
+   @param[out] public_key_digests Pointer to structure to hold the key digests for valid sig blocks
+
+
+   Note that this function doesn't read any eFuses, so it doesn't know if the
+   keys are ultimately trusted by the hardware or not
+
+   @return - ESP_OK if no signatures failed to verify, or if no valid signature blocks are found at all.
+           - ESP_FAIL if there's a valid signature block that doesn't verify using the included public key (unexpected!)
+*/
+static esp_err_t s_calculate_image_public_key_digests(uint32_t flash_offset, uint32_t flash_size, esp_image_sig_public_key_digests_t *public_key_digests)
+{
+    esp_err_t ret;
+    uint8_t image_digest[ESP_SECURE_BOOT_DIGEST_LEN] = {0};
+    uint8_t __attribute__((aligned(4))) key_digest[ESP_SECURE_BOOT_DIGEST_LEN] = {0};
+    size_t sig_block_addr = flash_offset + ALIGN_UP(flash_size, FLASH_SECTOR_SIZE);
+
+    ESP_LOGD(TAG, "calculating public key digests for sig blocks of image offset 0x%x (sig block offset 0x%x)", flash_offset, sig_block_addr);
+
+    bzero(public_key_digests, sizeof(esp_image_sig_public_key_digests_t));
+
+    ret = bootloader_sha256_flash_contents(flash_offset, sig_block_addr - flash_offset, image_digest);
+    if (ret != ESP_OK) {
+        ESP_LOGE(TAG, "error generating image digest, %d", ret);
+        return ret;
+    }
+
+    ESP_LOGD(TAG, "reading signature(s)");
+    const ets_secure_boot_signature_t *signatures = bootloader_mmap(sig_block_addr, sizeof(ets_secure_boot_signature_t));
+    if (signatures == NULL) {
+        ESP_LOGE(TAG, "bootloader_mmap(0x%x, 0x%x) failed", sig_block_addr, sizeof(ets_secure_boot_signature_t));
+        return ESP_FAIL;
+    }
+
+    /* Validating Signature block */
+    for (unsigned i = 0; i < SECURE_BOOT_NUM_BLOCKS; i++) {
+        const ets_secure_boot_sig_block_t *block = &signatures->block[i];
+
+        ret = validate_signature_block(block, i, image_digest);
+        if (ret != ESP_OK) {
+            ret = ESP_OK;  // past the last valid signature block
+            break;
+        }
+
+        /* Generating the SHA of the public key components in the signature block */
+        bootloader_sha256_handle_t sig_block_sha;
+        sig_block_sha = bootloader_sha256_start();
+        bootloader_sha256_data(sig_block_sha, &block->key, sizeof(block->key));
+        bootloader_sha256_finish(sig_block_sha, key_digest);
+
+        // Check we can verify the image using this signature and this key
+        uint8_t temp_verified_digest[ESP_SECURE_BOOT_DIGEST_LEN];
+        bool verified = ets_rsa_pss_verify(&block->key, block->signature, image_digest, temp_verified_digest);
+
+        if (!verified) {
+            /* We don't expect this: the signature blocks before we enable secure boot should all be verifiable or invalid,
+               so this is a fatal error
+            */
+            ret = ESP_FAIL;
+            ESP_LOGE(TAG, "Secure boot key (%d) verification failed.", i);
+            break;
+        }
+        ESP_LOGD(TAG, "Signature block (%d) is verified", i);
+        /* Copy the key digest to the buffer provided by the caller */
+        memcpy((void *)public_key_digests->key_digests[i], key_digest, ESP_SECURE_BOOT_DIGEST_LEN);
+        public_key_digests->num_digests++;
+    }
+
+    if (ret == ESP_OK && public_key_digests->num_digests > 0) {
+        ESP_LOGI(TAG, "Digests successfully calculated, %d valid signatures (image offset 0x%x)",
+                 public_key_digests->num_digests, flash_offset);
+    }
+
+    bootloader_munmap(signatures);
+    return ret;
+}
+
+static esp_err_t check_and_generate_secure_boot_keys(const esp_image_metadata_t *image_data)
+{
+    esp_err_t ret;
+#ifdef CONFIG_IDF_TARGET_ESP32
+    esp_efuse_purpose_t secure_boot_key_purpose[SECURE_BOOT_NUM_BLOCKS] = {
+        ESP_EFUSE_KEY_PURPOSE_SECURE_BOOT_V2,
+    };
+    esp_efuse_coding_scheme_t coding_scheme = esp_efuse_get_coding_scheme(EFUSE_BLK_SECURE_BOOT);
+    if (coding_scheme != EFUSE_CODING_SCHEME_NONE) {
+        ESP_LOGE(TAG, "No coding schemes are supported in secure boot v2.(Detected scheme: 0x%x)", coding_scheme);
+        return ESP_ERR_NOT_SUPPORTED;
+    }
+#else
+    esp_efuse_purpose_t secure_boot_key_purpose[SECURE_BOOT_NUM_BLOCKS] = {
+        ESP_EFUSE_KEY_PURPOSE_SECURE_BOOT_DIGEST0,
+        ESP_EFUSE_KEY_PURPOSE_SECURE_BOOT_DIGEST1,
+        ESP_EFUSE_KEY_PURPOSE_SECURE_BOOT_DIGEST2,
+    };
+#endif // CONFIG_IDF_TARGET_ESP32
+
+    /* Verify the bootloader */
+    esp_image_metadata_t bootloader_data = { 0 };
+    ret = esp_image_verify_bootloader_data(&bootloader_data);
+    if (ret != ESP_OK) {
+        ESP_LOGE(TAG, "bootloader image appears invalid! error %d", ret);
+        return ret;
+    }
+
+    /* Check if secure boot digests are present */
+    esp_efuse_block_t blocks[SECURE_BOOT_NUM_BLOCKS];
+    bool has_secure_boot_digest = false;
+    for (unsigned i = 0; i < SECURE_BOOT_NUM_BLOCKS; i++) {
+        blocks[i] = EFUSE_BLK_KEY_MAX;
+        bool tmp_has_key = esp_efuse_find_purpose(secure_boot_key_purpose[i], &blocks[i]);
+        if (tmp_has_key) { // For ESP32: esp_efuse_find_purpose() always returns True, need to check whether the key block is used or not.
+            tmp_has_key &= !esp_efuse_key_block_unused(blocks[i]);
+        }
+        has_secure_boot_digest |= tmp_has_key;
+    }
+
+    esp_image_sig_public_key_digests_t boot_key_digests = {0};
+    esp_image_sig_public_key_digests_t app_key_digests = {0};
+    ESP_LOGI(TAG, "Secure boot digests %s", has_secure_boot_digest ? "already present":"absent, generating..");
+
+    if (!has_secure_boot_digest) {
+        /* Generate the bootloader public key digests */
+        ret = s_calculate_image_public_key_digests(bootloader_data.start_addr, bootloader_data.image_len - SIG_BLOCK_PADDING, &boot_key_digests);
+        if (ret != ESP_OK) {
+            ESP_LOGE(TAG, "Bootloader signature block is invalid");
+            return ret;
+        }
+
+        if (boot_key_digests.num_digests == 0) {
+            ESP_LOGE(TAG, "No valid bootloader signature blocks found.");
+            return ESP_FAIL;
+        }
+        ESP_LOGI(TAG, "%d signature block(s) found appended to the bootloader.", boot_key_digests.num_digests);
+
+        ESP_LOGI(TAG, "Burning public key hash to eFuse");
+        ret = esp_efuse_write_keys(secure_boot_key_purpose, boot_key_digests.key_digests, boot_key_digests.num_digests);
+        if (ret != ESP_OK) {
+            if (ret == ESP_ERR_NOT_ENOUGH_UNUSED_KEY_BLOCKS) {
+                ESP_LOGE(TAG, "Bootloader signatures(%d) more than available key slots.", boot_key_digests.num_digests);
+            } else {
+                ESP_LOGE(TAG, "Failed to write efuse block with purpose (err=0x%x). Can't continue.", ret);
+            }
+            return ret;
+        }
+    } else {
+        for (unsigned i = 0; i < SECURE_BOOT_NUM_BLOCKS; i++) {
+#if SOC_EFUSE_REVOKE_BOOT_KEY_DIGESTS
+            if (esp_efuse_get_digest_revoke(i)) {
+                continue;
+            }
+#endif
+            if (esp_efuse_get_key_dis_read(blocks[i])) {
+                ESP_LOGE(TAG, "Key digest (BLK%d) read protected, aborting...", blocks[i]);
+                return ESP_FAIL;
+            }
+            if (esp_efuse_block_is_empty(blocks[i])) {
+                ESP_LOGE(TAG, "%d eFuse block is empty, aborting...", blocks[i]);
+                return ESP_FAIL;
+            }
+            esp_efuse_set_key_dis_write(blocks[i]);
+            ret = esp_efuse_read_block(blocks[i], boot_key_digests.key_digests[boot_key_digests.num_digests], 0,
+                                            sizeof(boot_key_digests.key_digests[0]) * 8);
+            if (ret) {
+                ESP_LOGE(TAG, "Error during reading %d eFuse block (err=0x%x)", blocks[i], ret);
+                return ret;
+            }
+            boot_key_digests.num_digests++;
+        }
+        if (boot_key_digests.num_digests == 0) {
+            ESP_LOGE(TAG, "No valid pre-loaded public key digest in eFuse");
+            return ESP_FAIL;
+        }
+        ESP_LOGW(TAG, "Using pre-loaded public key digest in eFuse");
+    }
+
+    /* Generate the application public key digests */
+    ret = s_calculate_image_public_key_digests(image_data->start_addr, image_data->image_len - SIG_BLOCK_PADDING, &app_key_digests);
+    if (ret != ESP_OK) {
+        ESP_LOGE(TAG, "Application signature block is invalid.");
+        return ret;
+    }
+
+    if (app_key_digests.num_digests == 0) {
+        ESP_LOGE(TAG, "No valid applications signature blocks found.");
+        return ESP_FAIL;
+    }
+
+    ESP_LOGI(TAG, "%d signature block(s) found appended to the app.", app_key_digests.num_digests);
+    if (app_key_digests.num_digests > boot_key_digests.num_digests) {
+        ESP_LOGW(TAG, "App has %d signature blocks but bootloader only has %d. Some keys missing from bootloader?");
+    }
+
+    /* Confirm if at least one public key from the application matches a public key in the bootloader
+        (Also, ensure if that public revoke bit is not set for the matched key) */
+    bool match = false;
+
+    for (unsigned i = 0; i < boot_key_digests.num_digests; i++) {
+#if SOC_EFUSE_REVOKE_BOOT_KEY_DIGESTS
+        if (esp_efuse_get_digest_revoke(i)) {
+            ESP_LOGI(TAG, "Key block(%d) has been revoked.", i);
+            continue; // skip if the key block is revoked
+        }
+#endif // SOC_EFUSE_REVOKE_BOOT_KEY_DIGESTS
+        for (unsigned j = 0; j < app_key_digests.num_digests; j++) {
+            if (!memcmp(boot_key_digests.key_digests[i], app_key_digests.key_digests[j], ESP_SECURE_BOOT_DIGEST_LEN)) {
+                ESP_LOGI(TAG, "Application key(%d) matches with bootloader key(%d).", j, i);
+                match = true;
+            }
+        }
+    }
+
+    if (match == false) {
+        ESP_LOGE(TAG, "No application key digest matches the bootloader key digest.");
+        return ESP_FAIL;
+    }
+
+#if SOC_EFUSE_REVOKE_BOOT_KEY_DIGESTS
+    /* Revoke the empty signature blocks */
+    if (boot_key_digests.num_digests < SECURE_BOOT_NUM_BLOCKS) {
+        /* The revocation index can be 0, 1, 2. Bootloader count can be 1,2,3. */
+        for (unsigned i = boot_key_digests.num_digests; i < SECURE_BOOT_NUM_BLOCKS; i++) {
+            ESP_LOGI(TAG, "Revoking empty key digest slot (%d)...", i);
+            esp_efuse_set_digest_revoke(i);
+        }
+    }
+#endif // SOC_EFUSE_REVOKE_BOOT_KEY_DIGESTS
+    return ESP_OK;
+}
+
+esp_err_t esp_secure_boot_v2_permanently_enable(const esp_image_metadata_t *image_data)
+{
+    ESP_LOGI(TAG, "enabling secure boot v2...");
+
+    if (esp_secure_boot_enabled()) {
+        ESP_LOGI(TAG, "secure boot v2 is already enabled, continuing..");
+        return ESP_OK;
+    }
+
+    esp_efuse_batch_write_begin(); /* Batch all efuse writes at the end of this function */
+
+    esp_err_t err;
+    err = check_and_generate_secure_boot_keys(image_data);
+    if (err != ESP_OK) {
+        esp_efuse_batch_write_cancel();
+        return err;
+    }
+
+    ESP_LOGI(TAG, "blowing secure boot efuse...");
+    err = esp_secure_boot_enable_secure_features();
+    if (err != ESP_OK) {
+        esp_efuse_batch_write_cancel();
+        return err;
+    }
+
+    err = esp_efuse_batch_write_commit();
+    if (err != ESP_OK) {
+        ESP_LOGE(TAG, "Error programming security eFuses (err=0x%x).", err);
+        return err;
+    }
+
+#ifdef CONFIG_SECURE_BOOT_ENABLE_AGGRESSIVE_KEY_REVOKE
+    assert(esp_efuse_read_field_bit(ESP_EFUSE_SECURE_BOOT_AGGRESSIVE_REVOKE));
+#endif
+
+    assert(esp_secure_boot_enabled());
+    ESP_LOGI(TAG, "Secure boot permanently enabled");
+
+    return ESP_OK;
+}
+
+#endif // CONFIG_SECURE_BOOT_V2_ENABLED

components/bootloader_support/src/secure_boot_v2/secure_boot_signatures_app.c

@@ -20,6 +20,7 @@
 #include <sys/param.h>
 #include "esp_secure_boot.h"
 #include "esp_ota_ops.h"
+#include "esp_efuse.h"
 
 // Secure boot V2 for app
 
@@ -100,10 +101,9 @@ static esp_err_t get_secure_boot_key_digests(esp_image_sig_public_key_digests_t
     return esp_secure_boot_get_signature_blocks_for_running_app(true, public_key_digests);
 #elif CONFIG_SECURE_BOOT_V2_ENABLED
     ESP_LOGI(TAG, "Take trusted digest key(s) from eFuse block(s)");
-#if SOC_EFUSE_SECURE_BOOT_KEY_DIGESTS > 1
     // Read key digests from efuse
     ets_secure_boot_key_digests_t efuse_trusted;
-    if (ets_secure_boot_read_key_digests(&efuse_trusted) == ETS_OK) {
+    if (esp_secure_boot_read_key_digests(&efuse_trusted) == ESP_OK) {
         for (unsigned i = 0; i < SECURE_BOOT_NUM_BLOCKS; i++) {
             if (efuse_trusted.key_digests[i] != NULL) {
                 memcpy(public_key_digests->key_digests[i], (uint8_t *)efuse_trusted.key_digests[i], ESP_SECURE_BOOT_DIGEST_LEN);
@@ -115,11 +115,6 @@ static esp_err_t get_secure_boot_key_digests(esp_image_sig_public_key_digests_t
         return ESP_OK;
     }
     return ESP_ERR_NOT_FOUND;
-#else
-    memcpy(public_key_digests->key_digests[0], (uint8_t *)EFUSE_BLK2_RDATA0_REG, ESP_SECURE_BOOT_DIGEST_LEN);
-    public_key_digests->num_digests = 1;
-    return ESP_OK;
-#endif // SOC_EFUSE_SECURE_BOOT_KEY_DIGESTS
 #endif // CONFIG_SECURE_BOOT_V2_ENABLED
 }
 

components/bootloader_support/src/secure_boot_v2/secure_boot_signatures_bootloader.c

@@ -13,6 +13,7 @@
 #include "esp_log.h"
 #include "esp_image_format.h"
 #include "esp_secure_boot.h"
+#include "esp_efuse.h"
 
 // Secure boot V2 for bootloader.
 
@@ -64,49 +65,38 @@ static esp_err_t validate_signature_block(const ets_secure_boot_sig_block_t *blo
 
 static esp_err_t get_secure_boot_key_digests(esp_image_sig_public_key_digests_t *public_key_digests)
 {
-#if SOC_EFUSE_SECURE_BOOT_KEY_DIGESTS > 1
     // Read key digests from efuse
     ets_secure_boot_key_digests_t trusted_keys;
     ets_secure_boot_key_digests_t trusted_key_copies[2];
-    ETS_STATUS ets_ret;
 
     memset(&trusted_keys, 0, sizeof(ets_secure_boot_key_digests_t));
     memset(trusted_key_copies, 0, 2 * sizeof(ets_secure_boot_key_digests_t));
 
-
-    ets_ret = ets_secure_boot_read_key_digests(&trusted_keys);
+    esp_err_t err = esp_secure_boot_read_key_digests(&trusted_keys);
 
     // Create the copies for FI checks (assuming result is ETS_OK, if it's not then it'll fail the fault check anyhow)
-    ets_secure_boot_read_key_digests(&trusted_key_copies[0]);
-    ets_secure_boot_read_key_digests(&trusted_key_copies[1]);
+    esp_secure_boot_read_key_digests(&trusted_key_copies[0]);
+    esp_secure_boot_read_key_digests(&trusted_key_copies[1]);
     ESP_FAULT_ASSERT(memcmp(&trusted_keys, &trusted_key_copies[0], sizeof(ets_secure_boot_key_digests_t)) == 0);
     ESP_FAULT_ASSERT(memcmp(&trusted_keys, &trusted_key_copies[1], sizeof(ets_secure_boot_key_digests_t)) == 0);
 
-    if (ets_ret == ETS_OK) {
+    if (err == ESP_OK) {
         for (unsigned i = 0; i < SECURE_BOOT_NUM_BLOCKS; i++) {
             if (trusted_keys.key_digests[i] != NULL) {
                 memcpy(public_key_digests->key_digests[i], (uint8_t *)trusted_keys.key_digests[i], ESP_SECURE_BOOT_DIGEST_LEN);
                 public_key_digests->num_digests++;
             }
         }
+#if SOC_EFUSE_SECURE_BOOT_KEY_DIGESTS == 1
+        if (esp_efuse_block_is_empty(EFUSE_BLK_SECURE_BOOT)) {
+            return ESP_ERR_NOT_FOUND;
+        }
+#endif // SOC_EFUSE_SECURE_BOOT_KEY_DIGESTS
         if (public_key_digests->num_digests > 0) {
             return ESP_OK;
         }
     }
     return ESP_ERR_NOT_FOUND;
-#else
-    bool all_zeroes = true;
-    uint32_t *reg = (uint32_t*)&public_key_digests->key_digests[0];
-    for (int i = 0; i < ESP_SECURE_BOOT_DIGEST_LEN / 4; i++) {
-        *(reg + i) = REG_READ(EFUSE_BLK2_RDATA0_REG + i * 4);
-        all_zeroes = all_zeroes && (*(reg + i) == 0);
-    }
-    if (all_zeroes) {
-        return ESP_ERR_NOT_FOUND;
-    }
-    public_key_digests->num_digests = 1;
-    return ESP_OK;
-#endif // SOC_EFUSE_SECURE_BOOT_KEY_DIGESTS
 }
 
 // if CONFIG_SECURE_BOOT_V2_ENABLED==y and key digests from eFuse are missing, then it is the first boot,