/* * ks_flash.c * ---------- * Keystore implementation in flash memory. * * Authors: Rob Austein, Fredrik Thulin * Copyright (c) 2015-2016, NORDUnet A/S All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are * met: * - Redistributions of source code must retain the above copyright notice, * this list of conditions and the following disclaimer. * * - Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * - Neither the name of the NORDUnet nor the names of its contributors may * be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ /* * This keystore driver operates over bare flash, versus over a flash file * system or flash translation layer. The block size is large enough to * hold an AES-keywrapped 4096-bit RSA key. Any remaining space in the key * block may be used to store attributes (opaque TLV blobs). If the * attributes overflow the key block, additional blocks may be added, but * no attribute may exceed the block size. */ #include #include #include #include "hal.h" #include "hal_internal.h" #include "last_gasp_pin_internal.h" #define HAL_OK CMIS_HAL_OK #include "stm-keystore.h" #undef HAL_OK /* * Known block states. * * C does not guarantee any particular representation for enums, so * including enums directly in the block header isn't safe. Instead, * we use an access method which casts when reading from the header. * Writing to the header isn't a problem, because C does guarantee * that enum is compatible with *some* integer type, it just doesn't * specify which one. */ typedef enum { BLOCK_TYPE_ERASED = 0xFF, /* Pristine erased block (candidate for reuse) */ BLOCK_TYPE_ZEROED = 0x00, /* Zeroed block (recently used) */ BLOCK_TYPE_KEY = 0x55, /* Block contains key material */ BLOCK_TYPE_PIN = 0xAA, /* Block contains PINs */ BLOCK_TYPE_UNKNOWN = -1, /* Internal code for "I have no clue what this is" */ } flash_block_type_t; /* * Block status. */ typedef enum { BLOCK_STATUS_LIVE = 0x66, /* This is a live flash block */ BLOCK_STATUS_TOMBSTONE = 0x44, /* This is a tombstone left behind during an update */ BLOCK_STATUS_UNKNOWN = -1, /* Internal code for "I have no clue what this is" */ } flash_block_status_t; /* * Common header for all flash block types. * A few of these fields are deliberately omitted from the CRC. */ typedef struct { uint8_t block_type; uint8_t block_status; hal_crc32_t crc; } flash_block_header_t; /* * Key block. Tail end of "der" field (after der_len) used for attributes. */ typedef struct { flash_block_header_t header; hal_uuid_t name; hal_key_type_t type; hal_curve_name_t curve; hal_key_flags_t flags; size_t der_len; unsigned attributes_len; uint8_t der[]; /* Must be last field -- C99 "flexible array member" */ } flash_key_block_t; #define SIZEOF_FLASH_KEY_BLOCK_DER \ (KEYSTORE_SUBSECTOR_SIZE - offsetof(flash_key_block_t, der)) /* * PIN block. Also includes space for backing up the KEK when * HAL_MKM_FLASH_BACKUP_KLUDGE is enabled. */ typedef struct { flash_block_header_t header; hal_ks_pin_t wheel_pin; hal_ks_pin_t so_pin; hal_ks_pin_t user_pin; #if HAL_MKM_FLASH_BACKUP_KLUDGE uint32_t kek_set; uint8_t kek[KEK_LENGTH]; #endif } flash_pin_block_t; #define FLASH_KEK_SET 0x33333333 /* * One flash block. */ typedef union { uint8_t bytes[KEYSTORE_SUBSECTOR_SIZE]; flash_block_header_t header; flash_key_block_t key; flash_pin_block_t pin; } flash_block_t; /* * In-memory cache. */ typedef struct { unsigned blockno; uint32_t lru; flash_block_t block; } cache_block_t; /* * In-memory database. * * The top-level structure is a static variable; the arrays are allocated at runtime * using hal_allocate_static_memory() because they can get kind of large. */ #ifndef KS_FLASH_CACHE_SIZE #define KS_FLASH_CACHE_SIZE 4 #endif #define NUM_FLASH_BLOCKS KEYSTORE_NUM_SUBSECTORS typedef struct { hal_ks_t ks; /* Must be first (C "subclassing") */ hal_ks_index_t ksi; hal_ks_pin_t wheel_pin; hal_ks_pin_t so_pin; hal_ks_pin_t user_pin; uint32_t cache_lru; cache_block_t *cache; } db_t; /* * PIN block gets the all-zeros UUID, which will never be returned by * the UUID generation code (by definition -- it's not a version 4 UUID). */ const static hal_uuid_t pin_uuid = {{0}}; /* * The in-memory database structure itself is small, but the arrays it * points to are large enough that they come from SDRAM allocated at * startup. */ static db_t db; /* * Type safe casts. */ static inline flash_block_type_t block_get_type(const flash_block_t * const block) { assert(block != NULL); return (flash_block_type_t) block->header.block_type; } static inline flash_block_status_t block_get_status(const flash_block_t * const block) { assert(block != NULL); return (flash_block_status_t) block->header.block_status; } /* * Pick unused or least-recently-used slot in our in-memory cache. * * Updating lru values is caller's problem: if caller is using a cache * slot as a temporary buffer and there's no point in caching the * result, leave the lru values alone and the right thing will happen. */ static inline flash_block_t *cache_pick_lru(void) { uint32_t best_delta = 0; int best_index = 0; for (int i = 0; i < KS_FLASH_CACHE_SIZE; i++) { if (db.cache[i].blockno == ~0) return &db.cache[i].block; const uint32_t delta = db.cache_lru - db.cache[i].lru; if (delta > best_delta) { best_delta = delta; best_index = i; } } db.cache[best_index].blockno = ~0; return &db.cache[best_index].block; } /* * Find a block in our in-memory cache; return block or NULL if not present. */ static inline flash_block_t *cache_find_block(const unsigned blockno) { for (int i = 0; i < KS_FLASH_CACHE_SIZE; i++) if (db.cache[i].blockno == blockno) return &db.cache[i].block; return NULL; } /* * Mark a block in our in-memory cache as being in current use. */ static inline void cache_mark_used(const flash_block_t * const block, const unsigned blockno) { for (int i = 0; i < KS_FLASH_CACHE_SIZE; i++) { if (&db.cache[i].block == block) { db.cache[i].blockno = blockno; db.cache[i].lru = ++db.cache_lru; return; } } } /* * Release a block from the in-memory cache. */ static inline void cache_release(const flash_block_t * const block) { if (block != NULL) cache_mark_used(block, ~0); } /* * Generate CRC-32 for a block. * * This function needs to understand the structure of * flash_block_header_t, so that it can skip over fields that * shouldn't be included in the CRC. */ static hal_crc32_t calculate_block_crc(const flash_block_t * const block) { assert(block != NULL); hal_crc32_t crc = hal_crc32_init(); crc = hal_crc32_update(crc, &block->header.block_type, sizeof(block->header.block_type)); crc = hal_crc32_update(crc, block->bytes + sizeof(flash_block_header_t), sizeof(*block) - sizeof(flash_block_header_t)); return hal_crc32_finalize(crc); } /* * Calculate offset of the block in the flash address space. */ static inline uint32_t block_offset(const unsigned blockno) { return blockno * KEYSTORE_SUBSECTOR_SIZE; } /* * Read a flash block. * * Flash read on the Alpha is slow enough that it pays to check the * first page before reading the rest of the block. */ static hal_error_t block_read(const unsigned blockno, flash_block_t *block) { if (block == NULL || blockno >= NUM_FLASH_BLOCKS || sizeof(*block) != KEYSTORE_SUBSECTOR_SIZE) return HAL_ERROR_IMPOSSIBLE; /* Sigh, magic numeric return codes */ if (keystore_read_data(block_offset(blockno), block->bytes, KEYSTORE_PAGE_SIZE) != 1) return HAL_ERROR_KEYSTORE_ACCESS; switch (block_get_type(block)) { case BLOCK_TYPE_ERASED: case BLOCK_TYPE_ZEROED: return HAL_OK; case BLOCK_TYPE_KEY: case BLOCK_TYPE_PIN: break; default: return HAL_ERROR_KEYSTORE_BAD_BLOCK_TYPE; } switch (block_get_status(block)) { case BLOCK_STATUS_LIVE: case BLOCK_STATUS_TOMBSTONE: break; default: return HAL_ERROR_KEYSTORE_BAD_BLOCK_TYPE; } /* Sigh, magic numeric return codes */ if (keystore_read_data(block_offset(blockno) + KEYSTORE_PAGE_SIZE, block->bytes + KEYSTORE_PAGE_SIZE, sizeof(*block) - KEYSTORE_PAGE_SIZE) != 1) return HAL_ERROR_KEYSTORE_ACCESS; if (calculate_block_crc(block) != block->header.crc) return HAL_ERROR_KEYSTORE_BAD_CRC; return HAL_OK; } /* * Read a block using the cache. Marking the block as used is left * for the caller, so we can avoid blowing out the cache when we * perform a ks_match() operation. */ static hal_error_t block_read_cached(const unsigned blockno, flash_block_t **block) { if (block == NULL) return HAL_ERROR_IMPOSSIBLE; if ((*block = cache_find_block(blockno)) != NULL) return HAL_OK; if ((*block = cache_pick_lru()) == NULL) return HAL_ERROR_IMPOSSIBLE; return block_read(blockno, *block); } /* * Convert a live block into a tombstone. Caller is responsible for * making sure that the block being converted is valid; since we don't * need to update the CRC for this, we just modify the first page. */ static hal_error_t block_deprecate(const unsigned blockno) { if (blockno >= NUM_FLASH_BLOCKS) return HAL_ERROR_IMPOSSIBLE; uint8_t page[KEYSTORE_PAGE_SIZE]; flash_block_header_t *header = (void *) page; uint32_t offset = block_offset(blockno); /* Sigh, magic numeric return codes */ if (keystore_read_data(offset, page, sizeof(page)) != 1) return HAL_ERROR_KEYSTORE_ACCESS; header->block_status = BLOCK_STATUS_TOMBSTONE; /* Sigh, magic numeric return codes */ if (keystore_write_data(offset, page, sizeof(page)) != 1) return HAL_ERROR_KEYSTORE_ACCESS; return HAL_OK; } /* * Zero (not erase) a flash block. Just need to zero the first page. */ static hal_error_t block_zero(const unsigned blockno) { if (blockno >= NUM_FLASH_BLOCKS) return HAL_ERROR_IMPOSSIBLE; uint8_t page[KEYSTORE_PAGE_SIZE] = {0}; /* Sigh, magic numeric return codes */ if (keystore_write_data(block_offset(blockno), page, sizeof(page)) != 1) return HAL_ERROR_KEYSTORE_ACCESS; return HAL_OK; } /* * Erase a flash block. Also see block_erase_maybe(), below. */ static hal_error_t block_erase(const unsigned blockno) { if (blockno >= NUM_FLASH_BLOCKS) return HAL_ERROR_IMPOSSIBLE; /* Sigh, magic numeric return codes */ if (keystore_erase_subsector(blockno) != 1) return HAL_ERROR_KEYSTORE_ACCESS; return HAL_OK; } /* * Erase a flash block if it hasn't already been erased. * May not be necessary, trying to avoid unnecessary wear. * * Unclear whether there's any sane reason why this needs to be * constant time, given how slow erasure is. But side channel attacks * can be tricky things, and it's theoretically possible that we could * leak information about, eg, key length, so we do constant time. */ static hal_error_t block_erase_maybe(const unsigned blockno) { if (blockno >= NUM_FLASH_BLOCKS) return HAL_ERROR_IMPOSSIBLE; uint8_t mask = 0xFF; for (uint32_t a = block_offset(blockno); a < block_offset(blockno + 1); a += KEYSTORE_PAGE_SIZE) { uint8_t page[KEYSTORE_PAGE_SIZE]; if (keystore_read_data(a, page, sizeof(page)) != 1) return HAL_ERROR_KEYSTORE_ACCESS; for (int i = 0; i < KEYSTORE_PAGE_SIZE; i++) mask &= page[i]; } return mask == 0xFF ? HAL_OK : block_erase(blockno); } /* * Write a flash block, calculating CRC when appropriate. */ static hal_error_t block_write(const unsigned blockno, flash_block_t *block) { if (block == NULL || blockno >= NUM_FLASH_BLOCKS || sizeof(*block) != KEYSTORE_SUBSECTOR_SIZE) return HAL_ERROR_IMPOSSIBLE; hal_error_t err = block_erase_maybe(blockno); if (err != HAL_OK) return err; switch (block_get_type(block)) { case BLOCK_TYPE_KEY: case BLOCK_TYPE_PIN: block->header.crc = calculate_block_crc(block); break; default: break; } /* Sigh, magic numeric return codes */ if (keystore_write_data(block_offset(blockno), block->bytes, sizeof(*block)) != 1) return HAL_ERROR_KEYSTORE_ACCESS; return HAL_OK; } /* * Update one flash block, including zombie jamboree. */ static hal_error_t block_update(const unsigned b1, flash_block_t *block, const hal_uuid_t * const uuid, int *hint) { if (block == NULL) return HAL_ERROR_IMPOSSIBLE; if (db.ksi.used == db.ksi.size) return HAL_ERROR_NO_KEY_INDEX_SLOTS; cache_release(block); hal_error_t err; unsigned b2; if ((err = block_deprecate(b1)) != HAL_OK || (err = hal_ks_index_replace(&db.ksi, uuid, &b2, hint)) != HAL_OK || (err = block_write(b2, block)) != HAL_OK || (err = block_zero(b1)) != HAL_OK) return err; cache_mark_used(block, b2); /* * Erase the first block in the free list. In case of restart, this * puts the block back at the head of the free list. */ return block_erase_maybe(db.ksi.index[db.ksi.used]); } /* * Forward reference. */ static hal_error_t fetch_pin_block(unsigned *b, flash_block_t **block); /* * Initialize keystore. This includes various tricky bits, some of * which attempt to preserve the free list ordering across reboots, to * improve our simplistic attempt at wear leveling, others attempt to * recover from unclean shutdown. */ static inline void *gnaw(uint8_t **mem, size_t *len, const size_t size) { if (mem == NULL || *mem == NULL || len == NULL || size > *len) return NULL; void *ret = *mem; *mem += size; *len -= size; return ret; } static hal_error_t ks_init(const hal_ks_driver_t * const driver, const int alloc) { hal_error_t err = HAL_OK; hal_ks_lock(); /* * Initialize the in-memory database. */ if (alloc) { size_t len = (sizeof(*db.ksi.index) * NUM_FLASH_BLOCKS + sizeof(*db.ksi.names) * NUM_FLASH_BLOCKS + sizeof(*db.cache) * KS_FLASH_CACHE_SIZE); /* * This is done as a single large allocation, rather than 3 smaller * allocations, to make it atomic - we need all 3, so either all * succeed or all fail. */ uint8_t *mem = hal_allocate_static_memory(len); if (mem == NULL) { err = HAL_ERROR_ALLOCATION_FAILURE; goto done; } memset(&db, 0, sizeof(db)); memset(mem, 0, len); db.ksi.index = gnaw(&mem, &len, sizeof(*db.ksi.index) * NUM_FLASH_BLOCKS); db.ksi.names = gnaw(&mem, &len, sizeof(*db.ksi.names) * NUM_FLASH_BLOCKS); db.cache = gnaw(&mem, &len, sizeof(*db.cache) * KS_FLASH_CACHE_SIZE); db.ksi.size = NUM_FLASH_BLOCKS; } else { memset(&db.wheel_pin, 0, sizeof(db.wheel_pin)); memset(&db.so_pin, 0, sizeof(db.so_pin)); memset(&db.user_pin, 0, sizeof(db.user_pin)); } db.ksi.used = 0; if (db.ksi.index == NULL || db.ksi.names == NULL || db.cache == NULL) { err = HAL_ERROR_IMPOSSIBLE; goto done; } for (int i = 0; i < KS_FLASH_CACHE_SIZE; i++) db.cache[i].blockno = ~0; /* * Scan existing content of flash to figure out what we've got. * This gets a bit involved due to the need to recover from things * like power failures at inconvenient times. */ flash_block_type_t block_types[NUM_FLASH_BLOCKS]; flash_block_status_t block_status[NUM_FLASH_BLOCKS]; flash_block_t *block = cache_pick_lru(); int first_erased = -1; uint16_t n = 0; if (block == NULL) { err = HAL_ERROR_IMPOSSIBLE; goto done; } for (int i = 0; i < NUM_FLASH_BLOCKS; i++) { /* * Read one block. If the CRC is bad or the block type is * unknown, it's old data we don't understand, something we were * writing when we crashed, or bad flash; in any of these cases, * we want the block to end up near the end of the free list. */ err = block_read(i, block); if (err == HAL_ERROR_KEYSTORE_BAD_CRC || err == HAL_ERROR_KEYSTORE_BAD_BLOCK_TYPE) block_types[i] = BLOCK_TYPE_UNKNOWN; else if (err == HAL_OK) block_types[i] = block_get_type(block); else goto done; switch (block_types[i]) { case BLOCK_TYPE_KEY: case BLOCK_TYPE_PIN: block_status[i] = block_get_status(block); break; default: block_status[i] = BLOCK_STATUS_UNKNOWN; } /* * First erased block we see is head of the free list. */ if (block_types[i] == BLOCK_TYPE_ERASED && first_erased < 0) first_erased = i; /* * If it's a valid data block, include it in the index. We remove * tombstones (if any) below, for now it's easiest to include them * in the index, so we can look them up by name if we must. */ const hal_uuid_t *uuid = NULL; switch (block_types[i]) { case BLOCK_TYPE_KEY: uuid = &block->key.name; break; case BLOCK_TYPE_PIN: uuid = &pin_uuid; break; default: /* Keep GCC happy */ break; } if (uuid != NULL) { db.ksi.names[i] = *uuid; db.ksi.index[n++] = i; } } db.ksi.used = n; assert(db.ksi.used <= db.ksi.size); /* * At this point we've built the (unsorted) index from all the valid * blocks. Now we need to insert free and unrecognized blocks into * the free list in our preferred order. It's possible that there's * a better way to do this than linear scan, but this is just * integer comparisons in a fairly small data set, so it's probably * not worth trying to optimize. */ if (n < db.ksi.size) for (int i = 0; i < NUM_FLASH_BLOCKS; i++) if (block_types[i] == BLOCK_TYPE_ERASED) db.ksi.index[n++] = i; if (n < db.ksi.size) for (int i = first_erased; i < NUM_FLASH_BLOCKS; i++) if (block_types[i] == BLOCK_TYPE_ZEROED) db.ksi.index[n++] = i; if (n < db.ksi.size) for (int i = 0; i < first_erased; i++) if (block_types[i] == BLOCK_TYPE_ZEROED) db.ksi.index[n++] = i; if (n < db.ksi.size) for (int i = 0; i < NUM_FLASH_BLOCKS; i++) if (block_types[i] == BLOCK_TYPE_UNKNOWN) db.ksi.index[n++] = i; assert(n == db.ksi.size); /* * Initialize the index. */ if ((err = hal_ks_index_setup(&db.ksi)) != HAL_OK) goto done; /* * We might want to call hal_ks_index_fsck() here, if we can figure * out some safe set of recovery actions we can take. */ /* * Deal with tombstones, now that the index is sorted. Tombstones * are blocks left behind when something bad (like a power failure) * happened while we updating. There can be at most one tombstone * and one live block for a given UUID. If we find no live block, * we need to restore it from the tombstone, after which we need to * zero the tombstone in either case. The sequence of operations * while updating is designed so that, barring a bug or a hardware * failure, we should never lose data. */ for (unsigned b_tomb = 0; b_tomb < NUM_FLASH_BLOCKS; b_tomb++) { if (block_status[b_tomb] != BLOCK_STATUS_TOMBSTONE) continue; hal_uuid_t name = db.ksi.names[b_tomb]; int where = -1; if ((err = hal_ks_index_find(&db.ksi, &name, NULL, &where)) != HAL_OK) goto done; if (b_tomb != db.ksi.index[where]) { if (db.ksi.used > where + 1 && b_tomb == db.ksi.index[where + 1]) where = where + 1; else if (0 <= where - 1 && b_tomb == db.ksi.index[where - 1]) where = where - 1; else { err = HAL_ERROR_IMPOSSIBLE; goto done; } } const int matches_next = where + 1 < db.ksi.used && !hal_uuid_cmp(&name, &db.ksi.names[db.ksi.index[where + 1]]); const int matches_prev = where - 1 >= 0 && !hal_uuid_cmp(&name, &db.ksi.names[db.ksi.index[where - 1]]); if ((matches_prev && matches_next) || (matches_prev && block_status[db.ksi.index[b_tomb - 1]] != BLOCK_STATUS_LIVE) || (matches_next && block_status[db.ksi.index[b_tomb + 1]] != BLOCK_STATUS_LIVE)) { err = HAL_ERROR_IMPOSSIBLE; goto done; } if (matches_prev || matches_next) { memmove(&db.ksi.index[where], &db.ksi.index[where + 1], (db.ksi.size - where - 1) * sizeof(*db.ksi.index)); db.ksi.index[db.ksi.size - 1] = b_tomb; } else { unsigned b_live; if ((err = block_read(b_tomb, block)) != HAL_OK) goto done; block->header.block_status = BLOCK_STATUS_LIVE; if ((err = hal_ks_index_replace(&db.ksi, &name, &b_live, &where)) != HAL_OK || (err = block_write(b_live, block)) != HAL_OK) goto done; block_status[b_live] = BLOCK_STATUS_LIVE; } if ((err = block_zero(b_tomb)) != HAL_OK) goto done; block_types[ b_tomb] = BLOCK_TYPE_ZEROED; block_status[b_tomb] = BLOCK_STATUS_UNKNOWN; } /* * Fetch or create the PIN block. */ err = fetch_pin_block(NULL, &block); if (err == HAL_OK) { db.wheel_pin = block->pin.wheel_pin; db.so_pin = block->pin.so_pin; db.user_pin = block->pin.user_pin; } else if (err != HAL_ERROR_KEY_NOT_FOUND) goto done; else { /* * We found no PIN block, so create one, with the user and so PINs * cleared and the wheel PIN set to the last-gasp value. The * last-gasp WHEEL PIN is a terrible answer, but we need some kind * of bootstrapping mechanism when all else fails. If you have a * better suggestion, we'd love to hear it. */ unsigned b; memset(block, 0xFF, sizeof(*block)); block->header.block_type = BLOCK_TYPE_PIN; block->header.block_status = BLOCK_STATUS_LIVE; block->pin.wheel_pin = db.wheel_pin = hal_last_gasp_pin; block->pin.so_pin = db.so_pin; block->pin.user_pin = db.user_pin; if ((err = hal_ks_index_add(&db.ksi, &pin_uuid, &b, NULL)) != HAL_OK) goto done; cache_mark_used(block, b); err = block_write(b, block); cache_release(block); if (err != HAL_OK) goto done; } /* * Erase first block on free list if it's not already erased. */ if (db.ksi.used < db.ksi.size && (err = block_erase_maybe(db.ksi.index[db.ksi.used])) != HAL_OK) goto done; /* * And we're finally done. */ db.ks.driver = driver; err = HAL_OK; done: hal_ks_unlock(); return err; } static hal_error_t ks_shutdown(const hal_ks_driver_t * const driver) { if (db.ks.driver != driver) return HAL_ERROR_KEYSTORE_ACCESS; return HAL_OK; } static hal_error_t ks_open(const hal_ks_driver_t * const driver, hal_ks_t **ks) { if (driver != hal_ks_token_driver || ks == NULL) return HAL_ERROR_BAD_ARGUMENTS; *ks = &db.ks; return HAL_OK; } static hal_error_t ks_close(hal_ks_t *ks) { if (ks != NULL && ks != &db.ks) return HAL_ERROR_BAD_ARGUMENTS; return HAL_OK; } static inline int acceptable_key_type(const hal_key_type_t type) { switch (type) { case HAL_KEY_TYPE_RSA_PRIVATE: case HAL_KEY_TYPE_EC_PRIVATE: case HAL_KEY_TYPE_RSA_PUBLIC: case HAL_KEY_TYPE_EC_PUBLIC: return 1; default: return 0; } } static hal_error_t ks_store(hal_ks_t *ks, hal_pkey_slot_t *slot, const uint8_t * const der, const size_t der_len) { if (ks != &db.ks || slot == NULL || der == NULL || der_len == 0 || !acceptable_key_type(slot->type)) return HAL_ERROR_BAD_ARGUMENTS; hal_error_t err = HAL_OK; flash_block_t *block; flash_key_block_t *k; uint8_t kek[KEK_LENGTH]; size_t kek_len; unsigned b; hal_ks_lock(); if ((block = cache_pick_lru()) == NULL) { err = HAL_ERROR_IMPOSSIBLE; goto done; } k = &block->key; if ((err = hal_ks_index_add(&db.ksi, &slot->name, &b, &slot->hint)) != HAL_OK) goto done; cache_mark_used(block, b); memset(block, 0xFF, sizeof(*block)); block->header.block_type = BLOCK_TYPE_KEY; block->header.block_status = BLOCK_STATUS_LIVE; k->name = slot->name; k->type = slot->type; k->curve = slot->curve; k->flags = slot->flags; k->der_len = SIZEOF_FLASH_KEY_BLOCK_DER; k->attributes_len = 0; if (db.ksi.used < db.ksi.size) err = block_erase_maybe(db.ksi.index[db.ksi.used]); if (err == HAL_OK) err = hal_mkm_get_kek(kek, &kek_len, sizeof(kek)); if (err == HAL_OK) err = hal_aes_keywrap(NULL, kek, kek_len, der, der_len, k->der, &k->der_len); memset(kek, 0, sizeof(kek)); if (err == HAL_OK) err = block_write(b, block); if (err == HAL_OK) goto done; memset(block, 0, sizeof(*block)); cache_release(block); (void) hal_ks_index_delete(&db.ksi, &slot->name, NULL, &slot->hint); done: hal_ks_unlock(); return err; } static hal_error_t ks_fetch(hal_ks_t *ks, hal_pkey_slot_t *slot, uint8_t *der, size_t *der_len, const size_t der_max) { if (ks != &db.ks || slot == NULL) return HAL_ERROR_BAD_ARGUMENTS; hal_error_t err = HAL_OK; flash_block_t *block; unsigned b; hal_ks_lock(); if ((err = hal_ks_index_find(&db.ksi, &slot->name, &b, &slot->hint)) != HAL_OK || (err = block_read_cached(b, &block)) != HAL_OK) goto done; if (block_get_type(block) != BLOCK_TYPE_KEY) { err = HAL_ERROR_KEYSTORE_WRONG_BLOCK_TYPE; /* HAL_ERROR_KEY_NOT_FOUND */ goto done; } cache_mark_used(block, b); flash_key_block_t *k = &block->key; slot->type = k->type; slot->curve = k->curve; slot->flags = k->flags; if (der == NULL && der_len != NULL) *der_len = k->der_len; if (der != NULL) { uint8_t kek[KEK_LENGTH]; size_t kek_len, der_len_; hal_error_t err; if (der_len == NULL) der_len = &der_len_; *der_len = der_max; if ((err = hal_mkm_get_kek(kek, &kek_len, sizeof(kek))) == HAL_OK) err = hal_aes_keyunwrap(NULL, kek, kek_len, k->der, k->der_len, der, der_len); memset(kek, 0, sizeof(kek)); } done: hal_ks_unlock(); return err; } static hal_error_t ks_delete(hal_ks_t *ks, hal_pkey_slot_t *slot) { if (ks != &db.ks || slot == NULL) return HAL_ERROR_BAD_ARGUMENTS; hal_error_t err = HAL_OK; unsigned b; hal_ks_lock(); if ((err = hal_ks_index_delete(&db.ksi, &slot->name, &b, &slot->hint)) != HAL_OK) goto done; cache_release(cache_find_block(b)); if ((err = block_zero(b)) != HAL_OK) goto done; err = block_erase_maybe(db.ksi.index[db.ksi.used]); done: hal_ks_unlock(); return err; } static inline hal_error_t locate_attributes(flash_block_t *block, uint8_t **bytes, size_t *bytes_len, unsigned **attrs_len) { if (block == NULL || bytes == NULL || bytes_len == NULL || attrs_len == NULL) return HAL_ERROR_IMPOSSIBLE; if (block_get_type(block) != BLOCK_TYPE_KEY) return HAL_ERROR_KEYSTORE_WRONG_BLOCK_TYPE; *attrs_len = &block->key.attributes_len; *bytes = block->key.der + block->key.der_len; *bytes_len = SIZEOF_FLASH_KEY_BLOCK_DER - block->key.der_len; return HAL_OK; } static hal_error_t ks_match(hal_ks_t *ks, const hal_client_handle_t client, const hal_session_handle_t session, const hal_key_type_t type, const hal_curve_name_t curve, const hal_key_flags_t mask, const hal_key_flags_t flags, const hal_pkey_attribute_t *attributes, const unsigned attributes_len, hal_uuid_t *result, unsigned *result_len, const unsigned result_max, const hal_uuid_t * const previous_uuid) { if (ks == NULL || (attributes == NULL && attributes_len > 0) || result == NULL || result_len == NULL || previous_uuid == NULL) return HAL_ERROR_BAD_ARGUMENTS; hal_error_t err = HAL_OK; flash_block_t *block; int i = -1; hal_ks_lock(); *result_len = 0; err = hal_ks_index_find(&db.ksi, previous_uuid, NULL, &i); if (err == HAL_ERROR_KEY_NOT_FOUND) i--; else if (err != HAL_OK) goto done; while (*result_len < result_max && ++i < db.ksi.used) { unsigned b = db.ksi.index[i]; if ((err = block_read_cached(b, &block)) != HAL_OK) goto done; if ((type != HAL_KEY_TYPE_NONE && type != block->key.type) || (curve != HAL_CURVE_NONE && curve != block->key.curve) || ((flags ^ block->key.flags) & mask) != 0) continue; if (attributes_len > 0) { uint8_t need_attr[attributes_len]; uint8_t *bytes = NULL; size_t bytes_len = 0; unsigned *attrs_len; int possible = 1; memset(need_attr, 1, sizeof(need_attr)); if ((err = locate_attributes(block, &bytes, &bytes_len, &attrs_len)) != HAL_OK) goto done; if (*attrs_len > 0) { hal_pkey_attribute_t attrs[*attrs_len]; if ((err = hal_ks_attribute_scan(bytes, bytes_len, attrs, *attrs_len, NULL)) != HAL_OK) goto done; for (int j = 0; possible && j < attributes_len; j++) { if (!need_attr[j]) continue; for (hal_pkey_attribute_t *a = attrs; a < attrs + *attrs_len; a++) { if (a->type != attributes[j].type) continue; need_attr[j] = 0; possible = (a->length == attributes[j].length && !memcmp(a->value, attributes[j].value, a->length)); break; } } } if (!possible || memchr(need_attr, 1, sizeof(need_attr)) != NULL) continue; } result[*result_len] = db.ksi.names[b]; ++*result_len; } err = HAL_OK; done: hal_ks_unlock(); return err; } static hal_error_t ks_set_attributes(hal_ks_t *ks, hal_pkey_slot_t *slot, const hal_pkey_attribute_t *attributes, const unsigned attributes_len) { if (ks != &db.ks || slot == NULL || attributes == NULL || attributes_len == 0) return HAL_ERROR_BAD_ARGUMENTS; hal_error_t err = HAL_OK; flash_block_t *block; unsigned b; hal_ks_lock(); { if ((err = hal_ks_index_find(&db.ksi, &slot->name, &b, &slot->hint)) != HAL_OK || (err = block_read_cached(b, &block)) != HAL_OK) goto done; cache_mark_used(block, b); uint8_t *bytes = NULL; size_t bytes_len = 0; unsigned *attrs_len; if ((err = locate_attributes(block, &bytes, &bytes_len, &attrs_len)) != HAL_OK) goto done; hal_pkey_attribute_t attrs[*attrs_len + attributes_len]; size_t total; if ((err = hal_ks_attribute_scan(bytes, bytes_len, attrs, *attrs_len, &total)) != HAL_OK) goto done; for (int i = 0; err == HAL_OK && i < attributes_len; i++) if (attributes[i].length == HAL_PKEY_ATTRIBUTE_NIL) err = hal_ks_attribute_delete(bytes, bytes_len, attrs, attrs_len, &total, attributes[i].type); else err = hal_ks_attribute_insert(bytes, bytes_len, attrs, attrs_len, &total, attributes[i].type, attributes[i].value, attributes[i].length); if (err == HAL_OK) err = block_update(b, block, &slot->name, &slot->hint); else cache_release(block); } done: hal_ks_unlock(); return err; } static hal_error_t ks_get_attributes(hal_ks_t *ks, hal_pkey_slot_t *slot, hal_pkey_attribute_t *attributes, const unsigned attributes_len, uint8_t *attributes_buffer, const size_t attributes_buffer_len) { if (ks != &db.ks || slot == NULL || attributes == NULL || attributes_len == 0 || attributes_buffer == NULL) return HAL_ERROR_BAD_ARGUMENTS; for (int i = 0; i < attributes_len; i++) { attributes[i].length = 0; attributes[i].value = NULL; } uint8_t *abuf = attributes_buffer; flash_block_t *block = NULL; hal_error_t err = HAL_OK; unsigned found = 0; unsigned b; hal_ks_lock(); { if ((err = hal_ks_index_find(&db.ksi, &slot->name, &b, &slot->hint)) != HAL_OK || (err = block_read_cached(b, &block)) != HAL_OK) goto done; cache_mark_used(block, b); uint8_t *bytes = NULL; size_t bytes_len = 0; unsigned *attrs_len; if ((err = locate_attributes(block, &bytes, &bytes_len, &attrs_len)) != HAL_OK) goto done; if (*attrs_len == 0) { err = HAL_ERROR_ATTRIBUTE_NOT_FOUND; goto done; } hal_pkey_attribute_t attrs[*attrs_len]; if ((err = hal_ks_attribute_scan(bytes, bytes_len, attrs, *attrs_len, NULL)) != HAL_OK) goto done; for (int i = 0; i < attributes_len; i++) { if (attributes[i].length > 0) continue; int j = 0; while (j < *attrs_len && attrs[j].type != attributes[i].type) j++; if (j >= *attrs_len) continue; found++; attributes[i].length = attrs[j].length; if (attributes_buffer_len == 0) continue; if (attrs[j].length > attributes_buffer + attributes_buffer_len - abuf) { err = HAL_ERROR_RESULT_TOO_LONG; goto done; } memcpy(abuf, attrs[j].value, attrs[j].length); attributes[i].value = abuf; abuf += attrs[j].length; } }; if (found < attributes_len && attributes_buffer_len > 0) err = HAL_ERROR_ATTRIBUTE_NOT_FOUND; else err = HAL_OK; done: hal_ks_unlock(); return err; } const hal_ks_driver_t hal_ks_token_driver[1] = {{ .init = ks_init, .shutdown = ks_shutdown, .open = ks_open, .close = ks_close, .store = ks_store, .fetch = ks_fetch, .delete = ks_delete, .match = ks_match, .set_attributes = ks_set_attributes, .get_attributes = ks_get_attributes }}; /* * The remaining functions aren't really part of the keystore API per se, * but they all involve non-key data which we keep in the keystore * because it's the flash we've got. */ /* * Special bonus init routine used only by the bootloader, so that it * can read PINs set by the main firmware. Yes, this is a kludge. We * could of course call the real ks_init() routine instead, but it's * slow, and we don't want to allow anything that would modify the * flash here, so having a special entry point for this kludge is * simplest, overall. Sigh. */ void hal_ks_init_read_only_pins_only(void) { unsigned b, best_seen = ~0; flash_block_t block[1]; hal_ks_lock(); for (b = 0; b < NUM_FLASH_BLOCKS; b++) { if (block_read(b, block) != HAL_OK || block_get_type(block) != BLOCK_TYPE_PIN) continue; best_seen = b; if (block_get_status(block) == BLOCK_STATUS_LIVE) break; } if (b != best_seen && best_seen != ~0 && block_read(best_seen, block) != HAL_OK) best_seen = ~0; if (best_seen == ~0) { memset(block, 0xFF, sizeof(*block)); block->pin.wheel_pin = hal_last_gasp_pin; } db.wheel_pin = block->pin.wheel_pin; db.so_pin = block->pin.so_pin; db.user_pin = block->pin.user_pin; hal_ks_unlock(); } /* * Fetch PIN. This is always cached, so just returned cached value. */ hal_error_t hal_get_pin(const hal_user_t user, const hal_ks_pin_t **pin) { if (pin == NULL) return HAL_ERROR_BAD_ARGUMENTS; hal_error_t err = HAL_OK; hal_ks_lock(); switch (user) { case HAL_USER_WHEEL: *pin = &db.wheel_pin; break; case HAL_USER_SO: *pin = &db.so_pin; break; case HAL_USER_NORMAL: *pin = &db.user_pin; break; default: err = HAL_ERROR_BAD_ARGUMENTS; } hal_ks_unlock(); return err; } /* * Fetch PIN block. hint = 0 because we know that the all-zeros UUID * should always sort to first slot in the index. */ static hal_error_t fetch_pin_block(unsigned *b, flash_block_t **block) { if (block == NULL) return HAL_ERROR_IMPOSSIBLE; hal_error_t err; int hint = 0; unsigned b_; if (b == NULL) b = &b_; if ((err = hal_ks_index_find(&db.ksi, &pin_uuid, b, &hint)) != HAL_OK || (err = block_read_cached(*b, block)) != HAL_OK) return err; cache_mark_used(*block, *b); if (block_get_type(*block) != BLOCK_TYPE_PIN) return HAL_ERROR_IMPOSSIBLE; return HAL_OK; } /* * Update the PIN block. This block should always be present, but we * have to do the zombie jamboree to make sure we write the new PIN * block before destroying the old one. hint = 0 because we know that * the all-zeros UUID should always sort to first slot in the index. */ static hal_error_t update_pin_block(const unsigned b, flash_block_t *block, const flash_pin_block_t * const new_data) { if (block == NULL || new_data == NULL || block_get_type(block) != BLOCK_TYPE_PIN) return HAL_ERROR_IMPOSSIBLE; int hint = 0; block->pin = *new_data; return block_update(b, block, &pin_uuid, &hint); } /* * Change a PIN. */ hal_error_t hal_set_pin(const hal_user_t user, const hal_ks_pin_t * const pin) { if (pin == NULL) return HAL_ERROR_BAD_ARGUMENTS; flash_block_t *block; hal_error_t err; unsigned b; hal_ks_lock(); if ((err = fetch_pin_block(&b, &block)) != HAL_OK) goto done; flash_pin_block_t new_data = block->pin; hal_ks_pin_t *dp, *bp; switch (user) { case HAL_USER_WHEEL: bp = &new_data.wheel_pin; dp = &db.wheel_pin; break; case HAL_USER_SO: bp = &new_data.so_pin; dp = &db.so_pin; break; case HAL_USER_NORMAL: bp = &new_data.user_pin; dp = &db.user_pin; break; default: err = HAL_ERROR_BAD_ARGUMENTS; goto done; } const hal_ks_pin_t old_pin = *dp; *dp = *bp = *pin; if ((err = update_pin_block(b, block, &new_data)) != HAL_OK) *dp = old_pin; done: hal_ks_unlock(); return err; } #if HAL_MKM_FLASH_BACKUP_KLUDGE /* * Horrible insecure kludge in lieu of a battery for the MKM. * * API here is a little strange: all calls pass a length parameter, * but any length other than the compiled in constant just returns an * immediate error, there's no notion of buffer max length vs buffer * used length, querying for the size of buffer really needed, or * anything like that. * * We might want to rewrite this some day, if we don't replace it with * a battery first. For now we just preserve the API as we found it * while re-implementing it on top of the new keystore. */ hal_error_t hal_mkm_flash_read_no_lock(uint8_t *buf, const size_t len) { if (buf != NULL && len != KEK_LENGTH) return HAL_ERROR_MASTERKEY_BAD_LENGTH; flash_block_t *block; hal_error_t err; unsigned b; if ((err = fetch_pin_block(&b, &block)) != HAL_OK) return err; if (block->pin.kek_set != FLASH_KEK_SET) return HAL_ERROR_MASTERKEY_NOT_SET; if (buf != NULL) memcpy(buf, block->pin.kek, len); return HAL_OK; } hal_error_t hal_mkm_flash_read(uint8_t *buf, const size_t len) { hal_ks_lock(); const hal_error_t err = hal_mkm_flash_read_no_lock(buf, len); hal_ks_unlock(); return err; } hal_error_t hal_mkm_flash_write(const uint8_t * const buf, const size_t len) { if (buf == NULL) return HAL_ERROR_BAD_ARGUMENTS; if (len != KEK_LENGTH) return HAL_ERROR_MASTERKEY_BAD_LENGTH; flash_block_t *block; hal_error_t err; unsigned b; hal_ks_lock(); if ((err = fetch_pin_block(&b, &block)) != HAL_OK) goto done; flash_pin_block_t new_data = block->pin; new_data.kek_set = FLASH_KEK_SET; memcpy(new_data.kek, buf, len); err = update_pin_block(b, block, &new_data); done: hal_ks_unlock(); return err; } hal_error_t hal_mkm_flash_erase(const size_t len) { if (len != KEK_LENGTH) return HAL_ERROR_MASTERKEY_BAD_LENGTH; flash_block_t *block; hal_error_t err; unsigned b; hal_ks_lock(); if ((err = fetch_pin_block(&b, &block)) != HAL_OK) goto done; flash_pin_block_t new_data = block->pin; new_data.kek_set = FLASH_KEK_SET; memset(new_data.kek, 0, len); err = update_pin_block(b, block, &new_data); done: hal_ks_unlock(); return err; } #endif /* HAL_MKM_FLASH_BACKUP_KLUDGE */ /* * Local variables: * indent-tabs-mode: nil * End: */