1 /* 2 * Copyright (C) 2016 The Android Open Source Project 3 * 4 * Permission is hereby granted, free of charge, to any person 5 * obtaining a copy of this software and associated documentation 6 * files (the "Software"), to deal in the Software without 7 * restriction, including without limitation the rights to use, copy, 8 * modify, merge, publish, distribute, sublicense, and/or sell copies 9 * of the Software, and to permit persons to whom the Software is 10 * furnished to do so, subject to the following conditions: 11 * 12 * The above copyright notice and this permission notice shall be 13 * included in all copies or substantial portions of the Software. 14 * 15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 16 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 17 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 18 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS 19 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN 20 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN 21 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 22 * SOFTWARE. 23 */ 24 /* 25 #if !defined(AVB_INSIDE_LIBAVB_AB_H) && !defined(AVB_COMPILATION) 26 #error \ 27 "Never include this file directly, include libavb_ab/libavb_ab.h instead." 28 #endif 29 */ 30 31 #ifndef AVB_AB_FLOW_H_ 32 #define AVB_AB_FLOW_H_ 33 34 #include <android_avb/avb_ab_ops.h> 35 36 #ifdef __cplusplus 37 extern "C" { 38 #endif 39 40 /* Magic for the A/B struct when serialized. */ 41 #define AVB_AB_MAGIC "\0AB0" 42 #define AVB_AB_MAGIC_LEN 4 43 44 /* Versioning for the on-disk A/B metadata - keep in sync with avbtool. */ 45 #define AVB_AB_MAJOR_VERSION 1 46 #define AVB_AB_MINOR_VERSION 0 47 48 /* Size of AvbABData struct. */ 49 #define AVB_AB_DATA_SIZE 512 50 51 /* Maximum values for slot data */ 52 #define AVB_AB_MAX_PRIORITY 15 53 #define AVB_AB_MAX_TRIES_REMAINING 7 54 55 /* Struct used for recording per-slot metadata. 56 * 57 * When serialized, data is stored in network byte-order. 58 */ 59 typedef struct AvbABSlotData { 60 /* Slot priority. Valid values range from 0 to AVB_AB_MAX_PRIORITY, 61 * both inclusive with 1 being the lowest and AVB_AB_MAX_PRIORITY 62 * being the highest. The special value 0 is used to indicate the 63 * slot is unbootable. 64 */ 65 uint8_t priority : 4; 66 67 /* Number of times left attempting to boot this slot ranging from 0 68 * to AVB_AB_MAX_TRIES_REMAINING. 69 */ 70 uint8_t tries_remaining : 3; 71 72 /* Non-zero if this slot has booted successfully, 0 otherwise. */ 73 uint8_t successful_boot : 1; 74 /* 1 if this slot is corrupted from a dm-verity corruption, 0 */ 75 /* otherwise. */ 76 uint8_t verity_corrupted : 1; 77 /* Reserved for future use. */ 78 uint8_t reserved : 7; 79 } AVB_ATTR_PACKED AvbABSlotData; 80 81 /* Struct used for recording A/B metadata. 82 * 83 * When serialized, data is stored in network byte-order. 84 */ 85 typedef struct AvbABData 86 { 87 /* NUL terminated active slot suffix. */ 88 char slot_suffix[4]; 89 /* Magic number used for identification - see AVB_AB_MAGIC. */ 90 uint8_t magic[AVB_AB_MAGIC_LEN]; 91 92 /* Version of on-disk struct - see AVB_AB_{MAJOR,MINOR}_VERSION. */ 93 uint8_t version_major; 94 95 /* Number of slots being managed. */ 96 uint8_t nb_slot : 3; 97 /* Number of times left attempting to boot recovery. */ 98 uint8_t recovery_tries_remaining : 3; 99 /* Padding to ensure |slots| field start eight bytes in. */ 100 uint8_t reserved1[2]; 101 102 /* Per-slot metadata. */ 103 AvbABSlotData slots[4]; 104 105 /* Reserved for future use. */ 106 uint8_t reserved2[8]; 107 //uint8_t reserved3[480]; 108 109 /* CRC32 of all 28 bytes preceding this field. */ 110 uint32_t crc32; 111 uint8_t version_minor; 112 } AVB_ATTR_PACKED AvbABData; 113 114 /* Copies |src| to |dest|, byte-swapping fields in the 115 * process. Returns false if the data is invalid (e.g. wrong magic, 116 * wrong CRC32 etc.), true otherwise. 117 */ 118 bool avb_ab_data_verify_and_byteswap(const AvbABData* src, AvbABData* dest); 119 120 /* Copies |src| to |dest|, byte-swapping fields in the process. Also 121 * updates the |crc32| field in |dest|. 122 */ 123 void avb_ab_data_update_crc_and_byteswap(const AvbABData* src, AvbABData* dest); 124 125 /* Initializes |data| such that it has two slots and both slots have 126 * maximum tries remaining. The CRC is not set. 127 */ 128 void avb_ab_data_init(AvbABData* data); 129 130 /* Reads A/B metadata from the 'misc' partition using |ops|. Returned 131 * data is properly byteswapped. Returns AVB_IO_RESULT_OK on 132 * success, error code otherwise. 133 * 134 * If the data read from disk is invalid (e.g. wrong magic or CRC 135 * checksum failure), the metadata will be reset using 136 * avb_ab_data_init() and then written to disk. 137 */ 138 AvbIOResult avb_ab_data_read(AvbABOps* ab_ops, AvbABData* data); 139 140 /* Load A/B metadata, like function avb_ab_data_read*/ 141 AvbIOResult load_metadata(AvbABOps* ab_ops, 142 AvbABData* ab_data, 143 AvbABData* ab_data_orig); 144 145 /* Writes A/B metadata to the 'misc' partition using |ops|. This will 146 * byteswap and update the CRC as needed. Returns AVB_IO_RESULT_OK on 147 * success, error code otherwise. 148 */ 149 AvbIOResult avb_ab_data_write(AvbABOps* ab_ops, const AvbABData* data); 150 151 /* Return codes used in avb_ab_flow(), see that function for 152 * documentation of each value. 153 */ 154 typedef enum { 155 AVB_AB_FLOW_RESULT_OK, 156 AVB_AB_FLOW_RESULT_OK_WITH_VERIFICATION_ERROR, 157 AVB_AB_FLOW_RESULT_ERROR_OOM, 158 AVB_AB_FLOW_RESULT_ERROR_IO, 159 AVB_AB_FLOW_RESULT_ERROR_NO_BOOTABLE_SLOTS, 160 AVB_AB_FLOW_RESULT_ERROR_INVALID_ARGUMENT 161 } AvbABFlowResult; 162 163 /* Get a textual representation of |result|. */ 164 const char* avb_ab_flow_result_to_string(AvbABFlowResult result); 165 166 /* High-level function to select a slot to boot. The following 167 * algorithm is used: 168 * 169 * 1. A/B metadata is loaded and validated using the 170 * read_ab_metadata() operation. Typically this means it's read from 171 * the 'misc' partition and if it's invalid then it's reset using 172 * avb_ab_data_init() and this reset metadata is returned. 173 * 174 * 2. All bootable slots listed in the A/B metadata are verified using 175 * avb_slot_verify(). If a slot is invalid or if it fails verification 176 * (and AVB_SLOT_VERIFY_FLAGS_ALLOW_VERIFICATION_ERROR is not set, see 177 * below), it will be marked as unbootable in the A/B metadata and the 178 * metadata will be saved to disk before returning. 179 * 180 * 3. If there are no bootable slots, the value 181 * AVB_AB_FLOW_RESULT_ERROR_NO_BOOTABLE_SLOTS is returned. 182 * 183 * 4. For each bootable slot, the Stored Rollback Indexes are updated 184 * such that for each rollback index location, the Stored Rollback 185 * Index is the largest number smaller than or equal to the Rollback 186 * Index of each slot. 187 * 188 * 5. The bootable slot with the highest priority is selected and 189 * returned in |out_data|. If this slot is already marked as 190 * successful, the A/B metadata is not modified. However, if the slot 191 * is not marked as bootable its |tries_remaining| count is 192 * decremented and the A/B metadata is saved to disk before returning. 193 * In either case the value AVB_AB_FLOW_RESULT_OK is returning. 194 * 195 * The partitions to load is given in |requested_partitions| as a 196 * NULL-terminated array of NUL-terminated strings. Typically the 197 * |requested_partitions| array only contains a single item for the 198 * boot partition, 'boot'. 199 * 200 * If the device is unlocked (and _only_ if it's unlocked), the 201 * AVB_SLOT_VERIFY_FLAGS_ALLOW_VERIFICATION_ERROR flag should be set 202 * in the |flags| parameter. This will allow considering slots as 203 * verified even when avb_slot_verify() returns 204 * AVB_SLOT_VERIFY_RESULT_ERROR_PUBLIC_KEY_REJECTED, 205 * AVB_SLOT_VERIFY_RESULT_ERROR_VERIFICATION, or 206 * AVB_SLOT_VERIFY_RESULT_ERROR_ROLLBACK_INDEX for the slot in 207 * question. 208 * 209 * Note that neither androidboot.slot_suffix nor androidboot.slot are 210 * set in the |cmdline| field in |AvbSlotVerifyData| - you will have 211 * to pass these yourself. 212 * 213 * If a slot was selected and it verified then AVB_AB_FLOW_RESULT_OK 214 * is returned. 215 * 216 * If a slot was selected but it didn't verify then 217 * AVB_AB_FLOW_RESULT_OK_WITH_VERIFICATION_ERROR is returned. This can 218 * only happen when the AVB_SLOT_VERIFY_FLAGS_ALLOW_VERIFICATION_ERROR 219 * flag is set. 220 * 221 * If an I/O operation - such as loading/saving metadata or checking 222 * rollback indexes - fail, the value AVB_AB_FLOW_RESULT_ERROR_IO is 223 * returned. 224 * 225 * If memory allocation fails, AVB_AB_FLOW_RESULT_ERROR_OOM is 226 * returned. 227 * 228 * If invalid arguments are passed, 229 * AVB_AB_FLOW_RESULT_ERROR_INVALID_ARGUMENT is returned. For example 230 * this can happen if using AVB_HASHTREE_ERROR_MODE_LOGGING without 231 * AVB_SLOT_VERIFY_FLAGS_ALLOW_VERIFICATION_ERROR. 232 * 233 * Reasonable behavior for handling AVB_AB_FLOW_RESULT_ERROR_NO_BOOTABLE_SLOTS 234 * is to initiate device repair (which is device-dependent). 235 */ 236 AvbABFlowResult avb_ab_flow(AvbABOps* ab_ops, 237 const char* const* requested_partitions, 238 AvbSlotVerifyFlags flags, 239 AvbHashtreeErrorMode hashtree_error_mode, 240 AvbSlotVerifyData** out_data); 241 242 AvbABFlowResult avb_ab_slot_select(AvbABOps* ab_ops,char select_slot[]); 243 244 /* Marks the slot with the given slot number as active. Returns 245 * AVB_IO_RESULT_OK on success, error code otherwise. 246 * 247 * This function is typically used by the OS updater when completing 248 * an update. It can also used by the firmware for implementing the 249 * "set_active" command. 250 */ 251 AvbIOResult avb_ab_mark_slot_active(AvbABOps* ab_ops, unsigned int slot_number); 252 253 /* Marks the slot with the given slot number as unbootable. Returns 254 * AVB_IO_RESULT_OK on success, error code otherwise. 255 * 256 * This function is typically used by the OS updater before writing to 257 * a slot. 258 */ 259 AvbIOResult avb_ab_mark_slot_unbootable(AvbABOps* ab_ops, 260 unsigned int slot_number); 261 262 /* Marks the slot with the given slot number as having booted 263 * successfully. Returns AVB_IO_RESULT_OK on success, error code 264 * otherwise. 265 * 266 * Calling this on an unbootable slot is an error - AVB_IO_RESULT_OK 267 * will be returned yet the function will have no side-effects. 268 * 269 * This function is typically used by the OS updater after having 270 * confirmed that the slot works as intended. 271 */ 272 AvbIOResult avb_ab_mark_slot_successful(AvbABOps* ab_ops, 273 unsigned int slot_number); 274 275 #ifdef __cplusplus 276 } 277 #endif 278 279 #endif /* AVB_AB_FLOW_H_ */ 280