| /* |
| * Copyright 2021 Google LLC |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| #include <libcr51sign/libcr51sign.h> |
| #include <stdio.h> |
| #include <string.h> |
| |
| #ifdef __cplusplus |
| extern "C" |
| { |
| #endif |
| |
| #ifndef USER_PRINT |
| #define CPRINTS(ctx, ...) fprintf(stderr, __VA_ARGS__) |
| #endif |
| |
| #define MEMBER_SIZE(type, field) sizeof(((type*)0)->field) |
| |
| // True of x is a power of two |
| #define POWER_OF_TWO(x) ((x) && !((x) & ((x)-1))) |
| |
| // Maximum version supported. Major revisions are not backwards compatible. |
| #define MAX_MAJOR_VERSION 1 |
| |
| // Descriptor alignment on the external EEPROM. |
| #define DESCRIPTOR_ALIGNMENT (64 * 1024) |
| |
| // SPS EEPROM sector size is 4KiB, since this is the smallest erasable size. |
| #define IMAGE_REGION_ALIGNMENT 4096 |
| |
| #define MAX_READ_SIZE 1024 |
| |
| #ifndef ARRAY_SIZE |
| #define ARRAY_SIZE(t) (sizeof(t) / sizeof(t[0])) |
| #endif |
| |
| // Values of SIGNATURE_OFFSET shuold be same for all sig types (2048,3072,4096) |
| #define SIGNATURE_OFFSET offsetof(struct signature_rsa3072_pkcs15, modulus) |
| |
| #ifndef BUILD_ASSERT |
| #define BUILD_ASSERT(cond) ((void)sizeof(char[1 - 2 * !(cond)])) |
| #endif |
| |
| typedef enum libcr51sign_validation_failure_reason failure_reason; |
| |
| // Returns the bytes size of keys used in the given signature_scheme. |
| // Return error if signature_scheme is invalid. |
| // |
| static failure_reason get_key_size(enum signature_scheme signature_scheme, |
| uint16_t* key_size) |
| { |
| switch (signature_scheme) |
| { |
| case SIGNATURE_RSA2048_PKCS15: |
| *key_size = 256; |
| return LIBCR51SIGN_SUCCESS; |
| case SIGNATURE_RSA3072_PKCS15: |
| *key_size = 384; |
| return LIBCR51SIGN_SUCCESS; |
| case SIGNATURE_RSA4096_PKCS15: |
| case SIGNATURE_RSA4096_PKCS15_SHA512: |
| *key_size = 512; |
| return LIBCR51SIGN_SUCCESS; |
| default: |
| return LIBCR51SIGN_ERROR_INVALID_SIG_SCHEME; |
| } |
| } |
| |
| // Returns the hash_type for a given signature scheme |
| // Returns error if scheme is invalid. |
| failure_reason get_hash_type_from_signature(enum signature_scheme scheme, |
| enum hash_type* type) |
| { |
| switch (scheme) |
| { |
| case SIGNATURE_RSA2048_PKCS15: |
| case SIGNATURE_RSA3072_PKCS15: |
| case SIGNATURE_RSA4096_PKCS15: |
| *type = HASH_SHA2_256; |
| return LIBCR51SIGN_SUCCESS; |
| case SIGNATURE_RSA4096_PKCS15_SHA512: |
| *type = HASH_SHA2_512; |
| return LIBCR51SIGN_SUCCESS; |
| default: |
| return LIBCR51SIGN_ERROR_INVALID_SIG_SCHEME; |
| } |
| } |
| |
| // Check if the given hash_type is supported. |
| // Returns error if hash_type is not supported. |
| static failure_reason is_hash_type_supported(enum hash_type type) |
| { |
| switch (type) |
| { |
| case HASH_SHA2_256: |
| case HASH_SHA2_512: |
| return LIBCR51SIGN_SUCCESS; |
| default: |
| return LIBCR51SIGN_ERROR_INVALID_HASH_TYPE; |
| } |
| } |
| |
| // Determines digest size for a given hash_type. |
| // Returns error if hash_type is not supported. |
| static failure_reason get_hash_digest_size(enum hash_type type, |
| uint32_t* size) |
| { |
| switch (type) |
| { |
| case HASH_SHA2_256: |
| *size = LIBCR51SIGN_SHA256_DIGEST_SIZE; |
| return LIBCR51SIGN_SUCCESS; |
| case HASH_SHA2_512: |
| *size = LIBCR51SIGN_SHA512_DIGEST_SIZE; |
| return LIBCR51SIGN_SUCCESS; |
| default: |
| return LIBCR51SIGN_ERROR_INVALID_HASH_TYPE; |
| } |
| } |
| |
| // Determines hash struct size for a given hash_type. |
| // Returns error if hash_type is not supported. |
| static failure_reason get_hash_struct_size(enum hash_type type, |
| uint32_t* size) |
| { |
| switch (type) |
| { |
| case HASH_SHA2_256: |
| *size = sizeof(struct hash_sha256); |
| return LIBCR51SIGN_SUCCESS; |
| case HASH_SHA2_512: |
| *size = sizeof(struct hash_sha256); |
| return LIBCR51SIGN_SUCCESS; |
| default: |
| return LIBCR51SIGN_ERROR_INVALID_HASH_TYPE; |
| } |
| } |
| |
| // Checks that: |
| // - The signing key is trusted |
| // - The target version is not denylisted |
| // If validating a staged update, also checks that: |
| // - The target image family matches the current image family |
| // - The image type transition is legal (i.e. dev -> *|| prod -> prod) or |
| // alternatively that the hardware ID is allowlisted |
| // Assuming the caller has performed following: |
| // board_get_base_key_index(); |
| // board_get_key_array |
| // Possible return codes: |
| // LIBCR51SIGN_SUCCESS = 0, |
| // LIBCR51SIGN_ERROR_RUNTIME_FAILURE = 1, |
| // LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR = 3, |
| // LIBCR51SIGN_ERROR_INVALID_IMAGE_FAMILY = 4, |
| // LIBCR51SIGN_ERROR_IMAGE_TYPE_DISALLOWED = 5, |
| |
| static failure_reason |
| validate_transition(const struct libcr51sign_ctx* ctx, |
| const struct libcr51sign_intf* intf, |
| uint32_t signature_struct_offset) |
| { |
| BUILD_ASSERT((offsetof(struct signature_rsa2048_pkcs15, modulus) == |
| SIGNATURE_OFFSET && |
| offsetof(struct signature_rsa3072_pkcs15, modulus) == |
| SIGNATURE_OFFSET && |
| offsetof(struct signature_rsa4096_pkcs15, modulus) == |
| SIGNATURE_OFFSET)); |
| |
| // Read up to the modulus. |
| enum |
| { |
| read_len = SIGNATURE_OFFSET |
| }; |
| uint8_t buffer[read_len]; |
| int rv; |
| rv = intf->read(ctx, signature_struct_offset, read_len, buffer); |
| if (rv != LIBCR51SIGN_SUCCESS) |
| { |
| CPRINTS(ctx, |
| "validate_transition: failed to read signature struct\n"); |
| return LIBCR51SIGN_ERROR_RUNTIME_FAILURE; |
| } |
| if (*(uint32_t*)buffer != SIGNATURE_MAGIC) |
| { |
| CPRINTS(ctx, "validate_transition: bad signature magic\n"); |
| return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR; |
| } |
| |
| if (ctx->descriptor.image_family != ctx->current_image_family && |
| ctx->descriptor.image_family != IMAGE_FAMILY_ALL && |
| ctx->current_image_family != IMAGE_FAMILY_ALL) |
| { |
| CPRINTS(ctx, "validate_transition: invalid image family\n"); |
| return LIBCR51SIGN_ERROR_INVALID_IMAGE_FAMILY; |
| } |
| |
| if (intf->is_production_mode == NULL) |
| { |
| CPRINTS(ctx, "validate_transition: missing is_production_mode\n"); |
| return LIBCR51SIGN_ERROR_INVALID_INTERFACE; |
| } |
| if (intf->is_production_mode() && |
| (ctx->descriptor.image_type == IMAGE_DEV)) |
| { |
| CPRINTS(ctx, "validate_transition: checking exemption allowlist\n"); |
| |
| // If function is NULL or if the function call return false, return |
| // error |
| if (intf->prod_to_dev_downgrade_allowed == NULL || |
| !intf->prod_to_dev_downgrade_allowed()) |
| { |
| CPRINTS(ctx, "validate_transition: illegal image type\n"); |
| return LIBCR51SIGN_ERROR_DEV_DOWNGRADE_DISALLOWED; |
| } |
| } |
| return LIBCR51SIGN_SUCCESS; |
| } |
| |
| // If caller had provided read_and_hash_update call that, otherwise call |
| // read and then update. |
| |
| static failure_reason |
| read_and_hash_update(const struct libcr51sign_ctx* ctx, |
| const struct libcr51sign_intf* intf, |
| uint32_t offset, uint32_t size) |
| { |
| uint8_t read_buffer[MAX_READ_SIZE]; |
| int rv; |
| int read_size; |
| |
| if (intf->read_and_hash_update) |
| { |
| rv = intf->read_and_hash_update((void*)ctx, offset, size); |
| } |
| else |
| { |
| if (!intf->hash_update) |
| { |
| CPRINTS(ctx, "read_and_hash_update: missing hash_update\n"); |
| return LIBCR51SIGN_ERROR_INVALID_INTERFACE; |
| } |
| do |
| { |
| read_size = size < MAX_READ_SIZE ? size : MAX_READ_SIZE; |
| rv = intf->read((void*)ctx, offset, read_size, read_buffer); |
| if (rv != LIBCR51SIGN_SUCCESS) |
| { |
| return LIBCR51SIGN_ERROR_RUNTIME_FAILURE; |
| } |
| rv = intf->hash_update((void*)ctx, read_buffer, read_size); |
| if (rv != LIBCR51SIGN_SUCCESS) |
| { |
| return LIBCR51SIGN_ERROR_RUNTIME_FAILURE; |
| } |
| offset += read_size; |
| size -= read_size; |
| } while (size > 0); |
| } |
| return rv; |
| } |
| |
| // Validates the image_region array, namely that: |
| // - The regions are aligned, contiguous & exhaustive |
| // - That the image descriptor resides in a static region |
| // |
| // If the array is consistent, proceeds to hash the static regions and |
| // validates the hash. d_offset is the absolute image descriptor offset |
| |
| static failure_reason validate_payload_regions( |
| const struct libcr51sign_ctx* ctx, struct libcr51sign_intf* intf, |
| uint32_t d_offset, struct libcr51sign_validated_regions* image_regions) |
| { |
| // Allocate buffer to accomodate largest supported hash-type(SHA512) |
| uint8_t magic_and_digest[MEMBER_SIZE(struct hash_sha512, hash_magic) + |
| LIBCR51SIGN_SHA512_DIGEST_SIZE]; |
| uint8_t dcrypto_digest[LIBCR51SIGN_SHA512_DIGEST_SIZE]; |
| uint32_t byte_count, region_count, image_size, hash_offset, digest_size; |
| uint32_t i; |
| uint8_t d_region_num = 0; |
| int rv; |
| const struct image_region* region; |
| |
| if (image_regions == NULL) |
| { |
| CPRINTS(ctx, "Missing image region input\n"); |
| return LIBCR51SIGN_ERROR_INVALID_REGION_INPUT; |
| } |
| |
| BUILD_ASSERT((MEMBER_SIZE(struct hash_sha256, hash_magic) == |
| MEMBER_SIZE(struct hash_sha512, hash_magic))); |
| image_size = ctx->descriptor.image_size; |
| region_count = ctx->descriptor.region_count; |
| hash_offset = d_offset + sizeof(struct image_descriptor) + |
| region_count * sizeof(struct image_region); |
| // Read the image_region array. |
| |
| if (region_count > ARRAY_SIZE(image_regions->image_regions)) |
| { |
| CPRINTS(ctx, "validate_payload_regions: " |
| "ctx->descriptor.region_count is greater " |
| "than LIBCR51SIGN_MAX_REGION_COUNT\n"); |
| return LIBCR51SIGN_ERROR_INVALID_REGION_SIZE; |
| } |
| |
| rv = intf->read(ctx, d_offset + sizeof(struct image_descriptor), |
| region_count * sizeof(struct image_region), |
| (uint8_t*)&image_regions->image_regions); |
| |
| image_regions->region_count = region_count; |
| |
| if (rv != LIBCR51SIGN_SUCCESS) |
| { |
| CPRINTS(ctx, |
| "validate_payload_regions: failed to read region array\n"); |
| return LIBCR51SIGN_ERROR_RUNTIME_FAILURE; |
| } |
| |
| // Validate that the regions are contiguous & exhaustive. |
| for (i = 0, byte_count = 0; i < region_count; i++) |
| { |
| region = image_regions->image_regions + i; |
| |
| CPRINTS(ctx, |
| "validate_payload_regions: region #%d \"%s\" (%x - %x)\n", |
| i, (const char*)region->region_name, region->region_offset, |
| region->region_offset + region->region_size); |
| if ((region->region_offset % IMAGE_REGION_ALIGNMENT) != 0 || |
| (region->region_size % IMAGE_REGION_ALIGNMENT) != 0) |
| { |
| CPRINTS(ctx, "validate_payload_regions: regions must be sector " |
| "aligned\n"); |
| return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR; |
| } |
| if (region->region_offset != byte_count || |
| region->region_size > image_size - byte_count) |
| { |
| CPRINTS(ctx, |
| "validate_payload_regions: invalid region array\n"); |
| return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR; |
| } |
| byte_count += region->region_size; |
| // The image descriptor must be part of a static region. |
| if (d_offset >= region->region_offset && d_offset < byte_count) |
| { |
| d_region_num = i; |
| CPRINTS( |
| ctx, |
| "validate_payload_regions: image descriptor in region %d\n", |
| i); |
| // The descriptor can't span regions. |
| if (ctx->descriptor.descriptor_area_size > byte_count || |
| !(region->region_attributes & IMAGE_REGION_STATIC)) |
| { |
| CPRINTS( |
| ctx, |
| "validate_payload_regions: descriptor must reside in " |
| "static region\n"); |
| return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR; |
| } |
| } |
| } |
| if (byte_count != image_size) |
| { |
| CPRINTS(ctx, "validate_payload_regions: invalid image size\n"); |
| return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR; |
| } |
| |
| rv = get_hash_digest_size(ctx->descriptor.hash_type, &digest_size); |
| if (rv != LIBCR51SIGN_SUCCESS) |
| { |
| return rv; |
| } |
| |
| rv = intf->read(ctx, hash_offset, |
| MEMBER_SIZE(struct hash_sha256, hash_magic) + |
| digest_size, |
| magic_and_digest); |
| if (rv != LIBCR51SIGN_SUCCESS) |
| { |
| CPRINTS( |
| ctx, |
| "validate_payload_regions: failed to read hash from flash\n"); |
| return LIBCR51SIGN_ERROR_RUNTIME_FAILURE; |
| } |
| if (*(uint32_t*)magic_and_digest != HASH_MAGIC) |
| { |
| CPRINTS(ctx, "validate_payload_regions: bad hash magic\n"); |
| return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR; |
| } |
| rv = intf->hash_init(ctx, ctx->descriptor.hash_type); |
| if (rv != LIBCR51SIGN_SUCCESS) |
| { |
| CPRINTS(ctx, "validate_payload_regions: hash_init failed\n"); |
| return LIBCR51SIGN_ERROR_RUNTIME_FAILURE; |
| } |
| for (i = 0; i < region_count; i++) |
| { |
| uint32_t hash_start, hash_size; |
| region = image_regions->image_regions + i; |
| |
| if (!(region->region_attributes & IMAGE_REGION_STATIC)) |
| { |
| continue; |
| } |
| hash_start = region->region_offset; |
| hash_size = region->region_size; |
| |
| // Skip the descriptor. |
| do |
| { |
| if (i == d_region_num) |
| { |
| hash_size = d_offset - hash_start; |
| } |
| |
| if (!hash_size) |
| { |
| hash_start += ctx->descriptor.descriptor_area_size; |
| hash_size = (region->region_offset + region->region_size - |
| hash_start); |
| } |
| CPRINTS("validate_payload_regions: hashing %s (%x - %x)\n", |
| (const char*)region->region_name, hash_start, |
| hash_start + hash_size); |
| // Read the image_region array. |
| rv = read_and_hash_update(ctx, intf, hash_start, hash_size); |
| if (rv != LIBCR51SIGN_SUCCESS) |
| { |
| return rv; |
| } |
| hash_start += hash_size; |
| } while (hash_start != region->region_offset + region->region_size); |
| } |
| rv = intf->hash_final((void*)ctx, (uint8_t*)dcrypto_digest); |
| |
| if (rv != LIBCR51SIGN_SUCCESS) |
| { |
| return LIBCR51SIGN_ERROR_RUNTIME_FAILURE; |
| } |
| |
| if (memcmp(magic_and_digest + |
| MEMBER_SIZE(struct hash_sha256, hash_magic), |
| dcrypto_digest, digest_size)) |
| { |
| CPRINTS(ctx, "validate_payload_regions: invalid hash\n"); |
| return LIBCR51SIGN_ERROR_INVALID_HASH; |
| } |
| // Image is valid. |
| return LIBCR51SIGN_SUCCESS; |
| } |
| |
| // Create empty image_regions to pass to validate_payload_regions |
| // Support validate_payload_regions_helper to remove image_regions as a |
| // required input. |
| |
| static failure_reason |
| allocate_and_validate_payload_regions(const struct libcr51sign_ctx* ctx, |
| struct libcr51sign_intf* intf, |
| uint32_t d_offset) |
| { |
| struct libcr51sign_validated_regions image_regions; |
| return validate_payload_regions(ctx, intf, d_offset, &image_regions); |
| } |
| |
| // Wrapper around validate_payload_regions to allow nullptr for |
| // image_regions. Calls allocate_and_validate_payload_regions when |
| // image_regions is nullptr to create placer holder image_regions. |
| |
| static failure_reason validate_payload_regions_helper( |
| const struct libcr51sign_ctx* ctx, struct libcr51sign_intf* intf, |
| uint32_t d_offset, struct libcr51sign_validated_regions* image_regions) |
| { |
| if (image_regions) |
| { |
| return validate_payload_regions(ctx, intf, d_offset, image_regions); |
| } |
| |
| return allocate_and_validate_payload_regions(ctx, intf, d_offset); |
| } |
| |
| // Check if the given signature_scheme is supported. |
| // Returns nonzero on error, zero on success |
| |
| static failure_reason |
| is_signature_scheme_supported(enum signature_scheme scheme) |
| { |
| switch (scheme) |
| { |
| case SIGNATURE_RSA2048_PKCS15: |
| case SIGNATURE_RSA3072_PKCS15: |
| case SIGNATURE_RSA4096_PKCS15: |
| case SIGNATURE_RSA4096_PKCS15_SHA512: |
| return LIBCR51SIGN_SUCCESS; |
| default: |
| return LIBCR51SIGN_ERROR_INVALID_SIG_SCHEME; |
| } |
| } |
| |
| // Returns size of signature struct size in |size| |
| // Returns nonzero on error, zero on success |
| |
| static failure_reason |
| get_signature_struct_size(enum signature_scheme scheme, uint32_t* size) |
| { |
| switch (scheme) |
| { |
| case SIGNATURE_RSA2048_PKCS15: |
| *size = sizeof(struct signature_rsa2048_pkcs15); |
| return LIBCR51SIGN_SUCCESS; |
| case SIGNATURE_RSA3072_PKCS15: |
| *size = sizeof(struct signature_rsa3072_pkcs15); |
| return LIBCR51SIGN_SUCCESS; |
| case SIGNATURE_RSA4096_PKCS15: |
| case SIGNATURE_RSA4096_PKCS15_SHA512: |
| *size = sizeof(struct signature_rsa4096_pkcs15); |
| return LIBCR51SIGN_SUCCESS; |
| default: |
| return LIBCR51SIGN_ERROR_INVALID_SIG_SCHEME; |
| } |
| } |
| |
| static failure_reason |
| get_signature_field_offset(enum signature_scheme scheme, |
| uint32_t* offset) |
| { |
| switch (scheme) |
| { |
| case SIGNATURE_RSA2048_PKCS15: |
| *offset = offsetof(struct signature_rsa2048_pkcs15, signature); |
| return LIBCR51SIGN_SUCCESS; |
| case SIGNATURE_RSA3072_PKCS15: |
| *offset = offsetof(struct signature_rsa3072_pkcs15, signature); |
| return LIBCR51SIGN_SUCCESS; |
| case SIGNATURE_RSA4096_PKCS15: |
| case SIGNATURE_RSA4096_PKCS15_SHA512: |
| *offset = offsetof(struct signature_rsa4096_pkcs15, signature); |
| return LIBCR51SIGN_SUCCESS; |
| default: |
| return LIBCR51SIGN_ERROR_INVALID_SIG_SCHEME; |
| } |
| } |
| |
| // Validates the signature (of type scheme) read from "device" at |
| //"raw_signature_offset" with "public_key" over a SHA256/SHA512 digest of |
| // EEPROM area "data_offset:data_size". |
| |
| static failure_reason validate_signature( |
| const struct libcr51sign_ctx* ctx, const struct libcr51sign_intf* intf, |
| uint32_t data_offset, uint32_t data_size, enum signature_scheme scheme, |
| uint32_t raw_signature_offset) |
| { |
| uint8_t signature[LIBCR51SIGN_MAX_SIGNATURE_SIZE]; |
| uint16_t key_size; |
| uint32_t digest_size; |
| uint8_t dcrypto_digest[LIBCR51SIGN_SHA512_DIGEST_SIZE]; |
| int rv; |
| enum hash_type hash_type; |
| |
| if (!intf->hash_init) |
| { |
| CPRINTS(ctx, "validate_signature: missing hash_init\n"); |
| return LIBCR51SIGN_ERROR_INVALID_INTERFACE; |
| } |
| rv = get_hash_type_from_signature(scheme, &hash_type); |
| if (rv != LIBCR51SIGN_SUCCESS) |
| { |
| CPRINTS( |
| ctx, |
| "validate_payload_regions: hash_type from signature failed\n"); |
| return rv; |
| } |
| rv = intf->hash_init(ctx, hash_type); |
| if (rv != LIBCR51SIGN_SUCCESS) |
| { |
| CPRINTS(ctx, "validate_payload_regions: hash_init failed\n"); |
| return LIBCR51SIGN_ERROR_RUNTIME_FAILURE; |
| } |
| rv = read_and_hash_update(ctx, intf, data_offset, data_size); |
| if (rv != LIBCR51SIGN_SUCCESS) |
| { |
| CPRINTS(ctx, "validate_signature: hash_update failed\n"); |
| return rv; |
| } |
| if (!intf->hash_final) |
| { |
| CPRINTS(ctx, "validate_signature: missing hash_final\n"); |
| return LIBCR51SIGN_ERROR_INVALID_INTERFACE; |
| } |
| rv = intf->hash_final((void*)ctx, dcrypto_digest); |
| if (rv != LIBCR51SIGN_SUCCESS) |
| { |
| CPRINTS(ctx, |
| "validate_signature: hash_final failed (status = %d)\n", |
| rv); |
| return LIBCR51SIGN_ERROR_RUNTIME_FAILURE; |
| } |
| rv = get_key_size(scheme, &key_size); |
| if (rv != LIBCR51SIGN_SUCCESS) |
| { |
| return rv; |
| } |
| |
| rv = intf->read(ctx, raw_signature_offset, key_size, signature); |
| if (rv != LIBCR51SIGN_SUCCESS) |
| { |
| CPRINTS( |
| ctx, |
| "validate_signature: failed to read signature (status = %d)\n", |
| rv); |
| return LIBCR51SIGN_ERROR_RUNTIME_FAILURE; |
| } |
| if (!intf->verify_signature) |
| { |
| CPRINTS(ctx, "validate_signature: missing verify_signature\n"); |
| return LIBCR51SIGN_ERROR_INVALID_INTERFACE; |
| } |
| rv = get_hash_digest_size(hash_type, &digest_size); |
| if (rv != LIBCR51SIGN_SUCCESS) |
| { |
| return rv; |
| } |
| rv = intf->verify_signature(ctx, scheme, signature, key_size, |
| dcrypto_digest, digest_size); |
| if (rv != LIBCR51SIGN_SUCCESS) |
| { |
| CPRINTS(ctx, |
| "validate_signature: verification failed (status = %d)\n", |
| rv); |
| return LIBCR51SIGN_ERROR_INVALID_SIGNATURE; |
| } |
| CPRINTS(ctx, "validate_signature: verification succeeded\n"); |
| return LIBCR51SIGN_SUCCESS; |
| } |
| |
| // Sanity checks the image descriptor & validates its signature. |
| // This function does not validate the image_region array or image hash. |
| // |
| //@param[in] ctx context which describes the image and holds opaque private |
| // data for the user of the library |
| //@param[in] intf function pointers which interface to the current system |
| // and environment |
| //@param offset Absolute image descriptor flash offset. |
| //@param relative_offset Image descriptor offset relative to image start. |
| //@param max_size Maximum size of the flash space in bytes. |
| //@param descriptor Output pointer to an image_descriptor struct |
| |
| static failure_reason validate_descriptor( |
| const struct libcr51sign_ctx* ctx, const struct libcr51sign_intf* intf, |
| uint32_t offset, uint32_t relative_offset, uint32_t max_size) |
| { |
| uint32_t max_descriptor_size, signed_size, signature_scheme, |
| signature_offset; |
| uint32_t signature_struct_offset, signature_struct_size, |
| hash_struct_size; |
| int rv; |
| |
| max_descriptor_size = max_size - relative_offset; |
| if (max_size < relative_offset || |
| max_descriptor_size < sizeof(struct image_descriptor)) |
| { |
| CPRINTS(ctx, "validate_descriptor: invalid arguments\n"); |
| return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR; |
| } |
| |
| rv = intf->read(ctx, offset, sizeof(ctx->descriptor), |
| (uint8_t*)&ctx->descriptor); |
| if (rv != LIBCR51SIGN_SUCCESS) |
| { |
| CPRINTS(ctx, "validate_descriptor: failed to read descriptor\n"); |
| return LIBCR51SIGN_ERROR_RUNTIME_FAILURE; |
| } |
| if (ctx->descriptor.descriptor_magic != DESCRIPTOR_MAGIC || |
| ctx->descriptor.descriptor_offset != relative_offset || |
| ctx->descriptor.region_count == 0 || |
| ctx->descriptor.descriptor_area_size > max_descriptor_size || |
| ctx->descriptor.image_size > max_size) |
| { |
| CPRINTS(ctx, "validate_descriptor: invalid descriptor\n"); |
| return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR; |
| } |
| if (intf->image_size_valid == NULL) |
| { |
| // Preserve original behavior of requiring exact image_size match if |
| // no operator is provided. |
| if (ctx->descriptor.image_size != max_size) |
| { |
| CPRINTS(ctx, "validate_descriptor: invalid image size\n"); |
| return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR; |
| } |
| } |
| else if (!intf->image_size_valid(ctx->descriptor.image_size)) |
| { |
| CPRINTS(ctx, "validate_descriptor: invalid image size\n"); |
| return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR; |
| } |
| if (ctx->descriptor.image_type != IMAGE_DEV && |
| ctx->descriptor.image_type != IMAGE_PROD && |
| ctx->descriptor.image_type != IMAGE_BREAKOUT && |
| ctx->descriptor.image_type != IMAGE_TEST && |
| ctx->descriptor.image_type != IMAGE_UNSIGNED_INTEGRITY) |
| { |
| CPRINTS(ctx, "validate_descriptor: bad image type\n"); |
| return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR; |
| } |
| // Although the image_descriptor struct supports unauthenticated |
| // images, Haven will not allow it. |
| // Haven only supports SHA256 + RSA2048/RSA3072_PKCS15 currently. |
| |
| signature_scheme = ctx->descriptor.signature_scheme; |
| |
| rv = is_signature_scheme_supported(signature_scheme); |
| if (rv != LIBCR51SIGN_SUCCESS) |
| { |
| return rv; |
| } |
| rv = is_hash_type_supported(ctx->descriptor.hash_type); |
| if (rv != LIBCR51SIGN_SUCCESS) |
| { |
| CPRINTS(ctx, "validate_payload_regions: invalid hash type\n"); |
| return rv; |
| } |
| if (ctx->descriptor.descriptor_major > MAX_MAJOR_VERSION || |
| ctx->descriptor.region_count > LIBCR51SIGN_MAX_REGION_COUNT) |
| { |
| CPRINTS(ctx, "validate_descriptor: unsupported descriptor\n"); |
| return LIBCR51SIGN_ERROR_UNSUPPORTED_DESCRIPTOR; |
| } |
| rv = get_signature_struct_size(signature_scheme, |
| &signature_struct_size); |
| if (rv != LIBCR51SIGN_SUCCESS) |
| { |
| return rv; |
| } |
| |
| // Compute the size of the signed portion of the image descriptor. |
| signed_size = sizeof(struct image_descriptor) + |
| ctx->descriptor.region_count * |
| sizeof(struct image_region); |
| rv = get_hash_struct_size(ctx->descriptor.hash_type, &hash_struct_size); |
| if (rv != LIBCR51SIGN_SUCCESS) |
| { |
| return rv; |
| } |
| signed_size += hash_struct_size; |
| if (ctx->descriptor.denylist_size) |
| { |
| signed_size += sizeof(struct denylist); |
| signed_size += ctx->descriptor.denylist_size * |
| sizeof(struct denylist_record); |
| } |
| if (ctx->descriptor.blob_size) |
| { |
| signed_size += sizeof(struct blob); |
| // Previous additions are guaranteed not to overflow. |
| if (ctx->descriptor.blob_size > |
| ctx->descriptor.descriptor_area_size - signed_size) |
| { |
| CPRINTS(ctx, "validate_descriptor: invalid blob size (0x%x)\n", |
| ctx->descriptor.blob_size); |
| return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR; |
| } |
| signed_size += ctx->descriptor.blob_size; |
| } |
| if (signature_struct_size > |
| ctx->descriptor.descriptor_area_size - signed_size) |
| { |
| CPRINTS(ctx, |
| "validate_descriptor: invalid descriptor area size " |
| "(expected = 0x%x, actual = 0x%x)\n", |
| ctx->descriptor.descriptor_area_size, |
| signed_size + signature_struct_size); |
| return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR; |
| } |
| signature_struct_offset = signed_size; |
| // Omit the actual signature. |
| rv = get_signature_field_offset(signature_scheme, &signature_offset); |
| if (rv != LIBCR51SIGN_SUCCESS) |
| { |
| return rv; |
| } |
| signed_size += signature_offset; |
| |
| // Lookup key & validate transition. |
| rv = validate_transition(ctx, intf, offset + signature_struct_offset); |
| |
| if (rv != LIBCR51SIGN_SUCCESS) |
| { |
| return rv; |
| } |
| return validate_signature(ctx, intf, offset, signed_size, |
| signature_scheme, offset + signed_size); |
| } |
| |
| // Scans the external EEPROM for a magic value at "alignment" boundaries. |
| // |
| //@param device Handle to the external EEPROM. |
| //@param magic 8-byte pattern to search for. |
| //@param start_offset Offset to begin searching at. |
| //@param limit Exclusive address (e.g. EEPROM size). |
| //@param alignment Alignment boundaries (POW2) to search on. |
| //@param header_offset Location to place the new header offset. |
| //@return LIBCR51SIGN_SUCCESS (or non-zero on error). |
| |
| int scan_for_magic_8(const struct libcr51sign_ctx* ctx, |
| const struct libcr51sign_intf* intf, uint64_t magic, |
| uint32_t start_offset, uint32_t limit, |
| uint32_t alignment, uint32_t* header_offset) |
| { |
| uint64_t read_data; |
| uint32_t offset; |
| int rv; |
| |
| if (limit <= start_offset || limit > ctx->end_offset || |
| limit < sizeof(magic) || !POWER_OF_TWO(alignment)) |
| { |
| return LIBCR51SIGN_ERROR_INVALID_ARGUMENT; |
| } |
| |
| if (!intf->read) |
| { |
| CPRINTS(ctx, "scan_for_magic_8: missing intf->read\n"); |
| return LIBCR51SIGN_ERROR_INVALID_INTERFACE; |
| } |
| // Align start_offset to the next valid boundary. |
| start_offset = ((start_offset - 1) & ~(alignment - 1)) + alignment; |
| for (offset = start_offset; offset < limit - sizeof(magic); |
| offset += alignment) |
| { |
| rv = intf->read((void*)ctx, offset, sizeof(read_data), |
| (uint8_t*)&read_data); |
| if (rv != LIBCR51SIGN_SUCCESS) |
| { |
| return rv; |
| } |
| if (read_data == magic) |
| { |
| if (header_offset) |
| { |
| *header_offset = offset; |
| } |
| return LIBCR51SIGN_SUCCESS; |
| } |
| } |
| // Failed to locate magic. |
| return LIBCR51SIGN_ERROR_FAILED_TO_LOCATE_MAGIC; |
| } |
| |
| // Check whether the signature on the image is valid. |
| // Validates the authenticity of an EEPROM image. Scans for & validates the |
| // signature on the image descriptor. If the descriptor validates, hashes |
| // the rest of the image to verify its integrity. |
| // |
| // @param[in] ctx - context which describes the image and holds opaque |
| // private |
| // data for the user of the library |
| // @param[in] intf - function pointers which interface to the current system |
| // and environment |
| // @param[out] image_regions - image_region pointer to an array for the |
| // output |
| // |
| // @return nonzero on error, zero on success |
| |
| failure_reason libcr51sign_validate( |
| const struct libcr51sign_ctx* ctx, struct libcr51sign_intf* intf, |
| struct libcr51sign_validated_regions* image_regions) |
| { |
| uint32_t image_limit = 0; |
| int rv, rv_first_desc = LIBCR51SIGN_SUCCESS; |
| uint32_t descriptor_offset; |
| |
| if (!ctx) |
| { |
| CPRINTS(ctx, "Missing context\n"); |
| return LIBCR51SIGN_ERROR_INVALID_CONTEXT; |
| } |
| else if (!intf) |
| { |
| CPRINTS(ctx, "Missing interface\n"); |
| return LIBCR51SIGN_ERROR_INVALID_INTERFACE; |
| } |
| |
| rv = scan_for_magic_8(ctx, intf, DESCRIPTOR_MAGIC, ctx->start_offset, |
| ctx->end_offset, DESCRIPTOR_ALIGNMENT, |
| &descriptor_offset); |
| while (rv == LIBCR51SIGN_SUCCESS) |
| { |
| CPRINTS(ctx, "validate: potential image descriptor found @%x\n", |
| descriptor_offset); |
| // Validation is split into 2 functions to minimize |
| // stack usage. |
| |
| rv = validate_descriptor(ctx, intf, descriptor_offset, |
| descriptor_offset - ctx->start_offset, |
| ctx->end_offset - ctx->start_offset); |
| if (rv != LIBCR51SIGN_SUCCESS) |
| { |
| CPRINTS(ctx, "validate: validate_descriptor() failed ec%d\n", |
| rv); |
| } |
| |
| if (rv == LIBCR51SIGN_SUCCESS) |
| { |
| rv = validate_payload_regions_helper( |
| ctx, intf, descriptor_offset, image_regions); |
| if (rv == LIBCR51SIGN_SUCCESS) |
| { |
| CPRINTS(ctx, "validate: success!\n"); |
| return rv; |
| } |
| CPRINTS(ctx, |
| "validate: validate_payload_regions() failed ec%d\n", |
| rv); |
| } |
| // Store the first desc fail reason if any |
| if (rv != LIBCR51SIGN_SUCCESS && |
| rv_first_desc == LIBCR51SIGN_SUCCESS) |
| rv_first_desc = rv; |
| |
| // scan_for_magic_8() will round up to the next aligned boundary. |
| descriptor_offset++; |
| image_limit = ctx->end_offset - ctx->start_offset; |
| rv = scan_for_magic_8(ctx, intf, DESCRIPTOR_MAGIC, |
| descriptor_offset, image_limit, |
| DESCRIPTOR_ALIGNMENT, &descriptor_offset); |
| } |
| CPRINTS(ctx, "validate: failed to validate image ec%d\n", rv); |
| // If desc validation failed for some reason then return that reason |
| if (rv_first_desc != LIBCR51SIGN_SUCCESS) |
| return rv_first_desc; |
| else |
| return rv; |
| } |
| |
| // @func to returns the libcr51sign error code as a string |
| // @param[in] ec - Error code |
| // @return error code in string format |
| |
| const char* libcr51sign_errorcode_to_string(failure_reason ec) |
| { |
| switch (ec) |
| { |
| case LIBCR51SIGN_SUCCESS: |
| return "Success"; |
| case LIBCR51SIGN_ERROR_RUNTIME_FAILURE: |
| return "Runtime Error Failure"; |
| case LIBCR51SIGN_ERROR_UNSUPPORTED_DESCRIPTOR: |
| return "Unsupported descriptor"; |
| case LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR: |
| return "Invalid descriptor"; |
| case LIBCR51SIGN_ERROR_INVALID_IMAGE_FAMILY: |
| return "Invalid image family"; |
| case LIBCR51SIGN_ERROR_IMAGE_TYPE_DISALLOWED: |
| return "Image type disallowed"; |
| case LIBCR51SIGN_ERROR_DEV_DOWNGRADE_DISALLOWED: |
| return "Dev downgrade disallowed"; |
| case LIBCR51SIGN_ERROR_UNTRUSTED_KEY: |
| return "Untrusted key"; |
| case LIBCR51SIGN_ERROR_INVALID_SIGNATURE: |
| return "Invalid signature"; |
| case LIBCR51SIGN_ERROR_INVALID_HASH: |
| return "Invalid hash"; |
| case LIBCR51SIGN_ERROR_INVALID_HASH_TYPE: |
| return "Invalid hash type"; |
| case LIBCR51SIGN_ERROR_INVALID_ARGUMENT: |
| return "Invalid Argument"; |
| case LIBCR51SIGN_ERROR_FAILED_TO_LOCATE_MAGIC: |
| return "Failed to locate descriptor"; |
| case LIBCR51SIGN_ERROR_INVALID_CONTEXT: |
| return "Invalid context"; |
| case LIBCR51SIGN_ERROR_INVALID_INTERFACE: |
| return "Invalid interface"; |
| case LIBCR51SIGN_ERROR_INVALID_SIG_SCHEME: |
| return "Invalid signature scheme"; |
| case LIBCR51SIGN_ERROR_INVALID_REGION_INPUT: |
| return "Invalid image region input"; |
| case LIBCR51SIGN_ERROR_INVALID_REGION_SIZE: |
| return "Invalid image region size"; |
| default: |
| return "Unknown error"; |
| } |
| } |
| |
| #ifdef __cplusplus |
| } // extern "C" |
| #endif |