| // Copyright 2017 The Fuchsia Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include <fcntl.h> |
| #include <stdbool.h> |
| #include <stddef.h> |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include <sys/stat.h> |
| #include <unistd.h> |
| |
| #ifdef __Fuchsia__ |
| #include <lib/zx/vmo.h> |
| #include <zircon/syscalls.h> |
| #endif |
| |
| #include <fbl/unique_fd.h> |
| #include <fbl/unique_ptr.h> |
| #include <zircon/types.h> |
| |
| #include "fvm/format.h" |
| |
| #define ZXDEBUG 0 |
| |
| namespace { |
| |
| constexpr size_t MetadataSizeOrZero(size_t disk_size, size_t slice_size) { |
| if (disk_size == 0 || slice_size == 0) { |
| return 0; |
| } |
| return fvm::MetadataSize(disk_size, slice_size); |
| } |
| |
| constexpr size_t UsableSlicesCountOrZero(size_t fvm_partition_size, size_t metadata_allocated_size, |
| size_t slice_size) { |
| if (slice_size == 0) { |
| return 0; |
| } |
| return (fvm_partition_size - 2 * metadata_allocated_size) / slice_size; |
| } |
| |
| // Return true if g1 is greater than or equal to g2. |
| // Safe against integer overflow. |
| bool generation_ge(uint64_t g1, uint64_t g2) { |
| if (g1 == UINT64_MAX && g2 == 0) { |
| return false; |
| } else if (g1 == 0 && g2 == UINT64_MAX) { |
| return true; |
| } |
| return g1 >= g2; |
| } |
| |
| // Validate the metadata's hash value. |
| // Returns 'true' if it matches, 'false' otherwise. |
| bool fvm_check_hash(const void* metadata, size_t metadata_size) { |
| ZX_DEBUG_ASSERT(metadata_size >= sizeof(fvm::Header)); |
| const fvm::Header* header = static_cast<const fvm::Header*>(metadata); |
| const void* metadata_after_hash = |
| reinterpret_cast<const void*>(header->hash + sizeof(header->hash)); |
| uint8_t empty_hash[sizeof(header->hash)]; |
| memset(empty_hash, 0, sizeof(empty_hash)); |
| |
| digest::Digest digest; |
| digest.Init(); |
| digest.Update(metadata, offsetof(fvm::Header, hash)); |
| digest.Update(empty_hash, sizeof(empty_hash)); |
| digest.Update(metadata_after_hash, |
| metadata_size - (offsetof(fvm::Header, hash) + sizeof(header->hash))); |
| digest.Final(); |
| return digest == header->hash; |
| } |
| |
| } // namespace |
| |
| #ifdef __cplusplus |
| |
| fvm::FormatInfo fvm::FormatInfo::FromSuperBlock(const Header& superblock) { |
| fvm::FormatInfo format_info; |
| format_info.metadata_allocated_size_ = superblock.allocation_table_size + kAllocTableOffset; |
| format_info.metadata_size_ = |
| MetadataSizeOrZero(superblock.fvm_partition_size, superblock.slice_size); |
| format_info.slice_size_ = superblock.slice_size; |
| format_info.slice_count_ = |
| UsableSlicesCountOrZero(superblock.fvm_partition_size, |
| format_info.metadata_allocated_size(), format_info.slice_size()); |
| return format_info; |
| } |
| |
| fvm::FormatInfo fvm::FormatInfo::FromPreallocatedSize(size_t initial_size, size_t max_size, |
| size_t slice_size) { |
| fvm::FormatInfo format_info; |
| format_info.metadata_allocated_size_ = MetadataSizeOrZero(max_size, slice_size); |
| format_info.metadata_size_ = MetadataSizeOrZero(initial_size, slice_size); |
| format_info.slice_size_ = slice_size; |
| format_info.slice_count_ = UsableSlicesCountOrZero( |
| initial_size, format_info.metadata_allocated_size(), format_info.slice_size()); |
| return format_info; |
| } |
| |
| fvm::FormatInfo fvm::FormatInfo::FromDiskSize(size_t disk_size, size_t slice_size) { |
| return FromPreallocatedSize(disk_size, disk_size, slice_size); |
| } |
| |
| #endif // __cplusplus |
| |
| void fvm_update_hash(void* metadata, size_t metadata_size) { |
| fvm::Header* header = static_cast<fvm::Header*>(metadata); |
| memset(header->hash, 0, sizeof(header->hash)); |
| digest::Digest digest; |
| const uint8_t* hash = digest.Hash(metadata, metadata_size); |
| memcpy(header->hash, hash, sizeof(header->hash)); |
| } |
| |
| zx_status_t fvm_validate_header(const void* metadata, const void* backup, size_t metadata_size, |
| const void** out) { |
| const fvm::Header* primary_header = static_cast<const fvm::Header*>(metadata); |
| const fvm::Header* backup_header = static_cast<const fvm::Header*>(backup); |
| |
| bool primary_valid = fvm_check_hash(metadata, metadata_size); |
| bool backup_valid = fvm_check_hash(backup, metadata_size); |
| |
| // Decide if we should use the primary or the backup copy of metadata |
| // for reading. |
| bool use_primary; |
| if (!primary_valid && !backup_valid) { |
| return ZX_ERR_BAD_STATE; |
| } else if (primary_valid && !backup_valid) { |
| use_primary = true; |
| } else if (!primary_valid && backup_valid) { |
| use_primary = false; |
| } else { |
| use_primary = generation_ge(primary_header->generation, backup_header->generation); |
| } |
| |
| const fvm::Header* header = use_primary ? primary_header : backup_header; |
| if (header->magic != fvm::kMagic) { |
| fprintf(stderr, "fvm: Bad magic\n"); |
| return ZX_ERR_BAD_STATE; |
| } |
| if (header->version > fvm::kVersion) { |
| fprintf(stderr, "fvm: Header Version does not match fvm driver\n"); |
| return ZX_ERR_BAD_STATE; |
| } |
| |
| // TODO(smklein): Additional validation.... |
| |
| if (out) { |
| *out = use_primary ? metadata : backup; |
| } |
| return ZX_OK; |
| } |