Sergii Dmytruk | 04bd965 | 2023-11-17 19:31:20 +0200 | [diff] [blame] | 1 | /* SPDX-License-Identifier: GPL-2.0-or-later */ |
| 2 | |
| 3 | #include "fv.h" |
| 4 | |
| 5 | #include <assert.h> |
| 6 | #include <stdbool.h> |
| 7 | #include <stdint.h> |
| 8 | #include <stdio.h> |
| 9 | #include <string.h> |
| 10 | |
| 11 | #include "udk2017.h" |
| 12 | |
| 13 | // The same as in `smmstore.h` header, which isn't in `commonlib`. |
Sergii Dmytruk | b2d86f1 | 2024-03-10 18:51:45 +0200 | [diff] [blame] | 14 | #define SMM_BLOCK_SIZE (64 * 1024) |
Sergii Dmytruk | 04bd965 | 2023-11-17 19:31:20 +0200 | [diff] [blame] | 15 | |
| 16 | static const EFI_GUID EfiVariableGuid = EFI_VARIABLE_GUID; |
| 17 | |
| 18 | static const EFI_GUID EfiAuthenticatedVariableGuid = |
| 19 | EFI_AUTHENTICATED_VARIABLE_GUID; |
| 20 | |
| 21 | static const EFI_GUID EfiSystemNvDataFvGuid = { |
| 22 | 0xfff12b8d, 0x7696, 0x4c8b, |
| 23 | { 0xa9, 0x85, 0x27, 0x47, 0x07, 0x5b, 0x4f, 0x50 } |
| 24 | }; |
| 25 | |
| 26 | static uint16_t calc_checksum(const uint16_t *hdr, size_t size) |
| 27 | { |
| 28 | assert(size % 2 == 0 && "Header can't have odd length."); |
| 29 | |
| 30 | uint16_t checksum = 0; |
| 31 | for (size_t i = 0; i < size / 2; ++i) |
| 32 | checksum += hdr[i]; |
| 33 | return checksum; |
| 34 | } |
| 35 | |
Sergii Dmytruk | b2d86f1 | 2024-03-10 18:51:45 +0200 | [diff] [blame] | 36 | bool fv_init(struct mem_range_t fv) |
Sergii Dmytruk | 04bd965 | 2023-11-17 19:31:20 +0200 | [diff] [blame] | 37 | { |
| 38 | if (fv.length % SMM_BLOCK_SIZE != 0) { |
| 39 | fprintf(stderr, |
| 40 | "Firmware Volume size is not a multiple of 64KiB\n"); |
| 41 | return false; |
| 42 | } |
| 43 | |
| 44 | memset(fv.start, 0xff, fv.length); |
| 45 | |
| 46 | const EFI_FIRMWARE_VOLUME_HEADER vol_hdr = { |
| 47 | .FileSystemGuid = EfiSystemNvDataFvGuid, |
| 48 | .FvLength = fv.length, |
| 49 | .Signature = EFI_FVH_SIGNATURE, |
| 50 | .Attributes = EFI_FVB2_READ_ENABLED_CAP |
| 51 | | EFI_FVB2_READ_STATUS |
| 52 | | EFI_FVB2_WRITE_ENABLED_CAP |
| 53 | | EFI_FVB2_WRITE_STATUS |
| 54 | | EFI_FVB2_STICKY_WRITE |
| 55 | | EFI_FVB2_MEMORY_MAPPED |
| 56 | | EFI_FVB2_ERASE_POLARITY, |
| 57 | .HeaderLength = sizeof(vol_hdr) |
| 58 | + sizeof(EFI_FV_BLOCK_MAP_ENTRY), |
| 59 | .Revision = EFI_FVH_REVISION, |
| 60 | .BlockMap[0] = { |
| 61 | .NumBlocks = fv.length / SMM_BLOCK_SIZE, |
| 62 | .Length = SMM_BLOCK_SIZE, |
| 63 | }, |
| 64 | }; |
| 65 | |
| 66 | EFI_FIRMWARE_VOLUME_HEADER *vol_hdr_dst = (void *)fv.start; |
| 67 | *vol_hdr_dst = vol_hdr; |
| 68 | vol_hdr_dst->BlockMap[1].NumBlocks = 0; |
| 69 | vol_hdr_dst->BlockMap[1].Length = 0; |
| 70 | |
| 71 | vol_hdr_dst->Checksum = |
| 72 | ~calc_checksum((const void *)vol_hdr_dst, vol_hdr.HeaderLength); |
| 73 | ++vol_hdr_dst->Checksum; |
| 74 | |
| 75 | const VARIABLE_STORE_HEADER var_store_hdr = { |
| 76 | // Authentication-related fields will be filled with 0xff. |
| 77 | .Signature = EfiAuthenticatedVariableGuid, |
| 78 | // Actual size of the storage is block size, the rest is |
| 79 | // Fault Tolerant Write (FTW) space and the FTW spare space. |
| 80 | .Size = SMM_BLOCK_SIZE - vol_hdr.HeaderLength, |
| 81 | .Format = VARIABLE_STORE_FORMATTED, |
| 82 | .State = VARIABLE_STORE_HEALTHY, |
| 83 | }; |
| 84 | |
| 85 | VARIABLE_STORE_HEADER *var_store_hdr_dst = |
| 86 | (void *)(fv.start + vol_hdr.HeaderLength); |
| 87 | *var_store_hdr_dst = var_store_hdr; |
| 88 | |
| 89 | return true; |
| 90 | } |
| 91 | |
| 92 | static bool guid_eq(const EFI_GUID *lhs, const EFI_GUID *rhs) |
| 93 | { |
| 94 | return memcmp(lhs, rhs, sizeof(*lhs)) == 0; |
| 95 | } |
| 96 | |
| 97 | static bool check_fw_vol_hdr(const EFI_FIRMWARE_VOLUME_HEADER *hdr, |
| 98 | size_t max_size) |
| 99 | { |
| 100 | if (hdr->Revision != EFI_FVH_REVISION || |
| 101 | hdr->Signature != EFI_FVH_SIGNATURE || |
| 102 | hdr->FvLength > max_size || |
| 103 | hdr->HeaderLength > max_size || |
| 104 | hdr->HeaderLength % 2 != 0) { |
| 105 | fprintf(stderr, "No firmware volume header present\n"); |
| 106 | return false; |
| 107 | } |
| 108 | |
| 109 | if (!guid_eq(&hdr->FileSystemGuid, &EfiSystemNvDataFvGuid)) { |
| 110 | fprintf(stderr, "Firmware volume GUID non-compatible\n"); |
| 111 | return false; |
| 112 | } |
| 113 | |
| 114 | uint16_t checksum = calc_checksum((const void *)hdr, hdr->HeaderLength); |
| 115 | if (checksum != 0) { |
| 116 | fprintf(stderr, |
| 117 | "Firmware Volume checksum is non-zero: 0x%04X\n", |
| 118 | checksum); |
| 119 | return false; |
| 120 | } |
| 121 | |
| 122 | return true; |
| 123 | } |
| 124 | |
| 125 | static bool check_var_store_hdr(const VARIABLE_STORE_HEADER *hdr, |
| 126 | size_t max_size, |
| 127 | bool *auth_vars) |
| 128 | { |
| 129 | *auth_vars = guid_eq(&hdr->Signature, &EfiAuthenticatedVariableGuid); |
| 130 | if (!*auth_vars && !guid_eq(&hdr->Signature, &EfiVariableGuid)) { |
| 131 | fprintf(stderr, "Variable store has unexpected GUID\n"); |
| 132 | return false; |
| 133 | } |
| 134 | |
| 135 | if (hdr->Size > max_size) { |
| 136 | fprintf(stderr, "Variable store size is too large: %zu > %zu\n", |
| 137 | (size_t)hdr->Size, max_size); |
| 138 | return false; |
| 139 | } |
| 140 | |
| 141 | if (hdr->Format != VARIABLE_STORE_FORMATTED) { |
| 142 | fprintf(stderr, "Variable store is not formatted\n"); |
| 143 | return false; |
| 144 | } |
| 145 | |
| 146 | if (hdr->State != VARIABLE_STORE_HEALTHY) { |
| 147 | fprintf(stderr, "Variable store is not in a healthy state\n"); |
| 148 | return false; |
| 149 | } |
| 150 | |
| 151 | return true; |
| 152 | } |
| 153 | |
Sergii Dmytruk | b2d86f1 | 2024-03-10 18:51:45 +0200 | [diff] [blame] | 154 | bool fv_parse(struct mem_range_t fv, struct mem_range_t *var_store, |
| 155 | bool *auth_vars) |
Sergii Dmytruk | 04bd965 | 2023-11-17 19:31:20 +0200 | [diff] [blame] | 156 | { |
| 157 | const EFI_FIRMWARE_VOLUME_HEADER *vol_hdr = (void *)fv.start; |
| 158 | if (!check_fw_vol_hdr(vol_hdr, fv.length)) { |
| 159 | fprintf(stderr, "No valid firmware volume was found\n"); |
| 160 | return false; |
| 161 | } |
| 162 | |
| 163 | uint8_t *fw_vol_data = fv.start + vol_hdr->HeaderLength; |
| 164 | size_t volume_size = fv.length - vol_hdr->HeaderLength; |
| 165 | const VARIABLE_STORE_HEADER *var_store_hdr = (void *)fw_vol_data; |
| 166 | if (!check_var_store_hdr(var_store_hdr, volume_size, auth_vars)) { |
| 167 | fprintf(stderr, "No valid variable store was found"); |
| 168 | return false; |
| 169 | } |
| 170 | |
| 171 | var_store->start = fw_vol_data + sizeof(*var_store_hdr); |
| 172 | var_store->length = volume_size - sizeof(*var_store_hdr); |
| 173 | return true; |
| 174 | } |