32756b165e
Goal is that multiple faults would be required to bypass a boot-time signature check. - Also strengthens some address range checks for safe app memory addresses - Change pre-enable logic to also check the bootloader signature before enabling SBV2 on ESP32 Add some additional checks for invalid sections: - Sections only partially in DRAM or IRAM are invalid - If a section is in D/IRAM, allow the possibility only some is in D/IRAM - Only pass sections that are entirely in the same type of RTC memory region
139 lines
4.6 KiB
C
139 lines
4.6 KiB
C
// Copyright 2020 Espressif Systems (Shanghai) PTE LTD
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef _ROM_SECURE_BOOT_H_
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#define _ROM_SECURE_BOOT_H_
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#include <stdint.h>
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#include "rsa_pss.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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struct ets_secure_boot_sig_block;
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struct ets_secure_boot_signature_t;
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typedef struct ets_secure_boot_sig_block ets_secure_boot_sig_block_t;
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typedef struct ets_secure_boot_signature ets_secure_boot_signature_t;
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typedef struct ets_secure_boot_key_digests ets_secure_boot_key_digests_t;
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/* 64KB 'staging buffer' for loading the verified bootloader
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Comes from the "shared buffers" region (see shared_buffers.h)
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The bootloader can't be safely linked into this address range
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(may be possible with some cleverness.)
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*/
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#define SECURE_BOOT_STAGING_BUFFER_START ((uint32_t)(g_shared_buffers.secure_boot_staging_buf))
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#define SECURE_BOOT_STAGING_BUFFER_SZ sizeof(g_shared_buffers.secure_boot_staging_buf)
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#define SECURE_BOOT_STAGING_BUFFER_END (SECURE_BOOT_STAGING_BUFFER_START + SECURE_BOOT_STAGING_BUFFER_SZ)
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/* Anti-FI measure: use full words for success/fail, instead of
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0/non-zero
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*/
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typedef enum {
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SB_SUCCESS = 0x3A5A5AA5,
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SB_FAILED = 0x7533885E,
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} ets_secure_boot_status_t;
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/* Verify and stage-load the bootloader image
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(reconfigures cache to map, loads trusted key digests from efuse,
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copies the bootloader into the staging buffer.)
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If allow_key_revoke is true and aggressive revoke efuse is set,
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any failed signature has its associated key revoked in efuse.
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If result is SB_SUCCESS, the "simple hash" of the bootloader
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is copied into verified_hash.
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*/
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ets_secure_boot_status_t ets_secure_boot_verify_stage_bootloader(uint8_t *verified_hash, bool allow_key_revoke);
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/* Verify bootloader image (reconfigures cache to map),
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with key digests provided as parameters.)
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Can be used to verify secure boot status before enabling
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secure boot permanently.
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If stage_load parameter is true, bootloader is copied into staging
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buffer in RAM at the same time.
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If result is SB_SUCCESS, the "simple hash" of the bootloader is
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copied into verified_hash.
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*/
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ets_secure_boot_status_t ets_secure_boot_verify_bootloader_with_keys(uint8_t *verified_hash, const ets_secure_boot_key_digests_t *trusted_keys, bool stage_load);
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/* Read key digests from efuse. Any revoked/missing digests will be
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marked as NULL
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*/
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ETS_STATUS ets_secure_boot_read_key_digests(ets_secure_boot_key_digests_t *trusted_keys);
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/* Verify supplied signature against supplied digest, using
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supplied trusted key digests.
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Doesn't reconfigure cache or any other hardware access except for RSA peripheral.
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If result is SB_SUCCESS, the image_digest value is copied into verified_digest.
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*/
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ets_secure_boot_status_t ets_secure_boot_verify_signature(const ets_secure_boot_signature_t *sig, const uint8_t *image_digest, const ets_secure_boot_key_digests_t *trusted_keys, uint8_t *verified_digest);
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/* Revoke a public key digest in efuse.
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@param index Digest to revoke. Must be 0, 1 or 2.
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*/
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void ets_secure_boot_revoke_public_key_digest(int index);
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#define ETS_SECURE_BOOT_V2_SIGNATURE_MAGIC 0xE7
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/* Secure Boot V2 signature block
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(Up to 3 in a signature sector are appended to the image)
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*/
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struct ets_secure_boot_sig_block {
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uint8_t magic_byte;
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uint8_t version;
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uint8_t _reserved1;
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uint8_t _reserved2;
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uint8_t image_digest[32];
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ets_rsa_pubkey_t key;
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uint8_t signature[384];
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uint32_t block_crc;
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uint8_t _padding[16];
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};
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_Static_assert(sizeof(ets_secure_boot_sig_block_t) == 1216, "invalid sig block size");
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#define SECURE_BOOT_NUM_BLOCKS 3
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/* V2 Secure boot signature sector (up to 3 blocks) */
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struct ets_secure_boot_signature {
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ets_secure_boot_sig_block_t block[SECURE_BOOT_NUM_BLOCKS];
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uint8_t _padding[4096 - (sizeof(ets_secure_boot_sig_block_t) * SECURE_BOOT_NUM_BLOCKS)];
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};
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_Static_assert(sizeof(ets_secure_boot_signature_t) == 4096, "invalid sig sector size");
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#define MAX_KEY_DIGESTS 3
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struct ets_secure_boot_key_digests {
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const void *key_digests[MAX_KEY_DIGESTS];
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bool allow_key_revoke;
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};
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#ifdef __cplusplus
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}
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#endif
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#endif /* _ROM_SECURE_BOOT_H_ */
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