From 378bcae718b7b8785b06c8cf82344e4f344a9215 Mon Sep 17 00:00:00 2001 From: Rob Austein Date: Fri, 30 Sep 2016 08:34:59 -0400 Subject: Multi-block object support in keystore. The main reason for supporting multi-block objects is to allow the PKCS #11 code to attach more attributes than will fit comfortably in a single flash block. This may turn out to be unnecessary once we've fleshed out the attribute storage and retrieval code; if so, we can simplify the code, but this way the keystore won't impose arbitrary (and somewhat inscrutable) size limits on PKCS #11 attributes for large keys. This snapshot passes light testing (PKCS #11 "make test" runs), but the tombstone recovery code in ks_init() is a bit involved, and needs more testing with simulated failures (probably induced under GDB). --- ks_flash.c | 299 ++++++++++++++++++++++++++++++++++++++++--------------------- 1 file changed, 196 insertions(+), 103 deletions(-) (limited to 'ks_flash.c') diff --git a/ks_flash.c b/ks_flash.c index df3b89b..475dcde 100644 --- a/ks_flash.c +++ b/ks_flash.c @@ -60,8 +60,8 @@ typedef enum { BLOCK_TYPE_ERASED = 0xFF, /* Pristine erased block (candidate for reuse) */ BLOCK_TYPE_ZEROED = 0x00, /* Zeroed block (recently used) */ - BLOCK_TYPE_KEYBLK = 0x55, /* Block contains key material */ - BLOCK_TYPE_PINBLK = 0xAA, /* Block contains PINs */ + 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; @@ -325,8 +325,8 @@ static hal_error_t block_read(const unsigned blockno, flash_block_t *block) case BLOCK_TYPE_ERASED: case BLOCK_TYPE_ZEROED: return HAL_OK; - case BLOCK_TYPE_KEYBLK: - case BLOCK_TYPE_PINBLK: + case BLOCK_TYPE_KEY: + case BLOCK_TYPE_PIN: break; default: return HAL_ERROR_KEYSTORE_BAD_BLOCK_TYPE; @@ -474,8 +474,8 @@ static hal_error_t block_write(const unsigned blockno, flash_block_t *block) return err; switch (block_get_type(block)) { - case BLOCK_TYPE_KEYBLK: - case BLOCK_TYPE_PINBLK: + case BLOCK_TYPE_KEY: + case BLOCK_TYPE_PIN: block->header.crc = calculate_block_crc(block); break; default: @@ -490,9 +490,16 @@ static hal_error_t block_write(const unsigned blockno, flash_block_t *block) } /* - * Initialize keystore. This includes some tricky bits that attempt - * to preserve the free list ordering across reboots, to improve our - * simplistic attempt at wear leveling. + * 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 hal_error_t ks_init(const hal_ks_driver_t * const driver) @@ -531,7 +538,6 @@ static hal_error_t ks_init(const hal_ks_driver_t * const driver) flash_block_status_t block_status[NUM_FLASH_BLOCKS]; flash_block_t *block = cache_pick_lru(); int first_erased = -1; - int saw_pins = 0; hal_error_t err; uint16_t n = 0; @@ -558,7 +564,7 @@ static hal_error_t ks_init(const hal_ks_driver_t * const driver) else return err; - if (block_types[i] == BLOCK_TYPE_KEYBLK || block_types[i] == BLOCK_TYPE_PINBLK) + if (block_types[i] == BLOCK_TYPE_KEY || block_types[i] == BLOCK_TYPE_PIN) block_status[i] = block_get_status(block); else block_status[i] = BLOCK_STATUS_UNKNOWN; @@ -571,32 +577,17 @@ static hal_error_t ks_init(const hal_ks_driver_t * const driver) first_erased = i; /* - * If it is or was a key block, remember its name. - * PIN blocks get the all-zeros UUID for ks_index purposes. - */ - - if (block_types[i] == BLOCK_TYPE_KEYBLK) - db.ksi.names[i] = block->key.name; - - /* - * If it is or was a PIN block, remember the PINs, but don't - * overwrite PINs from a current PIN block with PINs from a - * deprecated PIN block. + * 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. */ - if (block_types[i] == BLOCK_TYPE_PINBLK && (!saw_pins || block_status[i] == BLOCK_STATUS_LIVE)) { - db.wheel_pin = block->pin.wheel_pin; - db.so_pin = block->pin.so_pin; - db.user_pin = block->pin.user_pin; - saw_pins = 1; + if (block_types[i] == BLOCK_TYPE_KEY || block_types[i] == BLOCK_TYPE_PIN) { + db.ksi.names[i].name = block_types[i] == BLOCK_TYPE_KEY ? block->key.name : pin_uuid; + db.ksi.names[i].chunk = block->header.this_chunk; + db.ksi.index[n++] = i; } - /* - * If it's a current block, include it in the index. - */ - - if (block_status[i] == BLOCK_STATUS_LIVE) - db.ksi.index[n++] = i; } db.ksi.used = n; @@ -604,12 +595,12 @@ static hal_error_t ks_init(const hal_ks_driver_t * const driver) assert(db.ksi.used <= db.ksi.size); /* - * At this point we've built the (unsorted) index from all the - * current blocks. Now we need to insert free, deprecated, and - * unrecognized blocks into the free list in our preferred order. - * There's probably a more efficient way to do this, but this is - * just integer comparisons in a fairly small data set, so all of - * these loops should be pretty fast. + * 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) @@ -627,11 +618,6 @@ static hal_error_t ks_init(const hal_ks_driver_t * const driver) 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_status[i] == BLOCK_STATUS_TOMBSTONE) - 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) @@ -640,18 +626,39 @@ static hal_error_t ks_init(const hal_ks_driver_t * const driver) assert(n == db.ksi.size); /* - * Initialize the ks_index stuff. + * Initialize the index. */ if ((err = hal_ks_index_setup(&db.ksi)) != HAL_OK) return err; /* - * Deal with deprecated blocks. These are tombstones left behind - * when something bad happened while we updating a block. If write - * of the updated block completed, we have nothing to do other than - * cleaning up the tombstone, but if the write didn't complete, we - * need to resurrect the data from the tombstone. + * Deal with tombstones. These are blocks left behind when + * something bad (like a power failure) happened while we updating. + * The sequence of operations while updating is designed so that, + * barring a bug or a hardware failure, we should never lose data. + * + * For any tombstone we find, we start by looking for all the blocks + * with a matching UUID, then see what valid sequences we can + * construct from what we found. + * + * If we can construct a valid sequence of live blocks, the complete + * update was written out, and we just need to zero the tombstones. + * + * Otherwise, if we can construct a complete sequence of tombstone + * blocks, the update failed before it was completely written, so we + * have to zero the incomplete sequence of live blocks then restore + * from the tombstones. + * + * Otherwise, if the live and tombstone blocks taken together form a + * valid sequence, the update failed while deprecating the old live + * blocks, and the update itself was not written, so we need to + * restore the tombstones and leave the live blocks alone. + * + * If none of the above applies, we don't understand what happened, + * which is a symptom of either a bug or a hardware failure more + * serious than simple loss of power or reboot at an inconvenient + * time, so we error out to avoid accidental loss of data. */ for (int i = 0; i < NUM_FLASH_BLOCKS; i++) { @@ -659,56 +666,138 @@ static hal_error_t ks_init(const hal_ks_driver_t * const driver) if (block_status[i] != BLOCK_STATUS_TOMBSTONE) continue; - err = hal_ks_index_find(&db.ksi, &db.ksi.names[i], NULL); + hal_uuid_t name = db.ksi.names[i].name; + unsigned n_blocks; + int where = -1; - if (err != HAL_OK && err != HAL_ERROR_KEY_NOT_FOUND) + if ((err = hal_ks_index_find_range(&db.ksi, &name, 0, &n_blocks, NULL, &where)) != HAL_OK) return err; - unsigned b = ~0; + while (where > 0 && !hal_uuid_cmp(&name, &db.ksi.names[db.ksi.index[where - 1]].name)) { + where--; + n_blocks++; + } - if (err == HAL_ERROR_KEY_NOT_FOUND) { + int live_ok = 1, tomb_ok = 1, join_ok = 1; + unsigned n_live = 0, n_tomb = 0; + unsigned i_live = 0, i_tomb = 0; + + for (int j = 0; j < n_blocks; j++) { + unsigned b = db.ksi.index[where + j]; + switch (block_status[b]) { + case BLOCK_STATUS_LIVE: n_live++; break; + case BLOCK_STATUS_TOMBSTONE: n_tomb++; break; + default: return HAL_ERROR_IMPOSSIBLE; + } + } - /* - * Block did not exist, need to resurrect it. - */ + uint16_t live_blocks[n_live], tomb_blocks[n_tomb]; - hal_uuid_t name = db.ksi.names[i]; /* Paranoia */ + for (int j = 0; j < n_blocks; j++) { + unsigned b = db.ksi.index[where + j]; - if ((err = block_read(i, block)) != HAL_OK) + if ((err = block_read(b, block)) != HAL_OK) return err; - block->header.block_status = BLOCK_STATUS_LIVE; + join_ok &= block->header.this_chunk == j && block->header.total_chunks == n_blocks; + + switch (block_status[b]) { + case BLOCK_STATUS_LIVE: + live_blocks[i_live] = b; + live_ok &= block->header.this_chunk == i_live++ && block->header.total_chunks == n_live; + break; + case BLOCK_STATUS_TOMBSTONE: + tomb_blocks[i_tomb] = b; + tomb_ok &= block->header.this_chunk == i_tomb++ && block->header.total_chunks == n_tomb; + break; + default: + return HAL_ERROR_IMPOSSIBLE; + } + } - if ((err = hal_ks_index_add(&db.ksi, &name, &b)) != HAL_OK || - (err = block_write(b, block)) != HAL_OK) - return err; + if (!live_ok && !tomb_ok && !join_ok) + return HAL_ERROR_KEYSTORE_LOST_DATA; + + if (live_ok) { + for (int j = 0; j < n_tomb; j++) { + const unsigned b = tomb_blocks[j]; + if ((err = block_zero(b)) != HAL_OK) + return err; + block_types[b] = BLOCK_TYPE_ZEROED; + block_status[b] = BLOCK_STATUS_UNKNOWN; + } + } - if (block_types[i] == BLOCK_TYPE_PINBLK) - saw_pins = 1; + else if (tomb_ok) { + for (int j = 0; j < n_live; j++) { + const unsigned b = live_blocks[j]; + if ((err = block_zero(b)) != HAL_OK) + return err; + block_types[b] = BLOCK_TYPE_ZEROED; + block_status[b] = BLOCK_STATUS_UNKNOWN; + } } - /* - * Done with the tombstone, zero it. - */ + if (live_ok) { + memcpy(&db.ksi.index[where], live_blocks, n_live * sizeof(*db.ksi.index)); + memmove(&db.ksi.index[where + n_live], &db.ksi.index[where + n_blocks], + (db.ksi.size - where - n_blocks) * sizeof(*db.ksi.index)); + memcpy(&db.ksi.index[db.ksi.size - n_tomb], tomb_blocks, n_tomb * sizeof(*db.ksi.index)); + db.ksi.used -= n_tomb; + n_blocks = n_live; + } - if ((unsigned) i != b && (err = block_zero(i)) != HAL_OK) - return err; + else if (tomb_ok) { + memcpy(&db.ksi.index[where], tomb_blocks, n_tomb * sizeof(*db.ksi.index)); + memmove(&db.ksi.index[where + n_tomb], &db.ksi.index[where + n_blocks], + (db.ksi.size - where - n_blocks) * sizeof(*db.ksi.index)); + memcpy(&db.ksi.index[db.ksi.size - n_live], live_blocks, n_live * sizeof(*db.ksi.index)); + db.ksi.used -= n_live; + n_blocks = n_tomb; + } + + for (int j = 0; j < n_blocks; j++) { + unsigned b1 = db.ksi.index[where + j]; + if (block_status[b1] != BLOCK_STATUS_TOMBSTONE) + continue; + if ((err = block_read(b1, block)) != HAL_OK) + return err; + block->header.block_status = BLOCK_STATUS_LIVE; + int hint = where + j; + unsigned b2; + if ((err = hal_ks_index_replace(&db.ksi, &name, j, &b2, &hint)) != HAL_OK || + (err = block_write(b2, block)) != HAL_OK) + return err; + block_status[b2] = BLOCK_STATUS_LIVE; + block_types[b1] = BLOCK_TYPE_ZEROED; + } } - /* - * If we didn't see a PIN block, 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. - */ + 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) + return err; + + 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. + */ - if (!saw_pins) { unsigned b; memset(block, 0xFF, sizeof(*block)); - block->header.block_type = BLOCK_TYPE_PINBLK; + block->header.block_type = BLOCK_TYPE_PIN; block->header.block_status = BLOCK_STATUS_LIVE; block->header.total_chunks = 1; block->header.this_chunk = 0; @@ -717,7 +806,7 @@ static hal_error_t ks_init(const hal_ks_driver_t * const driver) 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)) != HAL_OK) + if ((err = hal_ks_index_add(&db.ksi, &pin_uuid, 0, &b, NULL)) != HAL_OK) return err; cache_mark_used(block, b); @@ -802,14 +891,14 @@ static hal_error_t ks_store(hal_ks_t *ks, if (block == NULL) return HAL_ERROR_IMPOSSIBLE; - if ((err = hal_ks_index_add(&db.ksi, &slot->name, &b)) != HAL_OK) + if ((err = hal_ks_index_add(&db.ksi, &slot->name, 0, &b, NULL)) != HAL_OK) return err; cache_mark_used(block, b); memset(block, 0xFF, sizeof(*block)); - block->header.block_type = BLOCK_TYPE_KEYBLK; + block->header.block_type = BLOCK_TYPE_KEY; block->header.block_status = BLOCK_STATUS_LIVE; block->header.total_chunks = 1; block->header.this_chunk = 0; @@ -831,7 +920,7 @@ static hal_error_t ks_store(hal_ks_t *ks, memset(block, 0, sizeof(*block)); cache_release(block); - (void) hal_ks_index_delete(&db.ksi, &slot->name, NULL); + (void) hal_ks_index_delete(&db.ksi, &slot->name, 0, NULL, NULL); return err; } @@ -846,11 +935,11 @@ static hal_error_t ks_fetch(hal_ks_t *ks, hal_error_t err; unsigned b; - if ((err = hal_ks_index_find(&db.ksi, &slot->name, &b)) != HAL_OK || - (err = block_read_cached(b, &block)) != HAL_OK) + if ((err = hal_ks_index_find(&db.ksi, &slot->name, 0, &b, NULL)) != HAL_OK || + (err = block_read_cached(b, &block)) != HAL_OK) return err; - if (block_get_type(block) != BLOCK_TYPE_KEYBLK) + if (block_get_type(block) != BLOCK_TYPE_KEY) return HAL_ERROR_KEY_NOT_FOUND; cache_mark_used(block, b); @@ -896,7 +985,7 @@ static hal_error_t ks_delete(hal_ks_t *ks, hal_error_t err; unsigned b; - if ((err = hal_ks_index_delete(&db.ksi, &slot->name, &b)) != HAL_OK) + if ((err = hal_ks_index_delete(&db.ksi, &slot->name, 0, &b, NULL)) != HAL_OK) return err; cache_release(cache_find_block(b)); @@ -931,7 +1020,7 @@ static hal_error_t ks_list(hal_ks_t *ks, if ((err = block_read_cached(b, &block)) != HAL_OK) return err; - if (block_get_type(block) != BLOCK_TYPE_KEYBLK) + if (block_get_type(block) != BLOCK_TYPE_KEY || block->header.this_chunk > 0) continue; result[*result_len].type = block->key.type; @@ -982,23 +1071,29 @@ hal_error_t hal_get_pin(const hal_user_t user, } /* - * Fetch PIN block. + * 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 (b == NULL || block == NULL) + if (block == NULL) return HAL_ERROR_IMPOSSIBLE; hal_error_t err; + int hint = 0; + unsigned b_; - if ((err = hal_ks_index_find(&db.ksi, &pin_uuid, b)) != HAL_OK || - (err = block_read_cached(*b, block)) != HAL_OK) + if (b == NULL) + b = &b_; + + if ((err = hal_ks_index_find(&db.ksi, &pin_uuid, 0, 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_PINBLK) + if (block_get_type(*block) != BLOCK_TYPE_PIN) return HAL_ERROR_IMPOSSIBLE; return HAL_OK; @@ -1007,22 +1102,19 @@ static hal_error_t fetch_pin_block(unsigned *b, flash_block_t **block) /* * Update the PIN block. This block should always be present, but we * have to dance a bit to make sure we write the new PIN block before - * destroying the old one. - * - * In theory we could simplify and speed this up a bit by taking - * advantage of knowing that the PIN block is always db.ksi.index[0] - * (because of the all-zeros UUID). Maybe later. + * destroying the old one. hint = 0 because we know that the all-zeros + * UUID should always sort to first slot in the index. * - * More generally, most of what happens here is part of updating any - * block, not just a PIN block, so we'll probably want to refactor - * once we get to the point where we need to update key blocks too. + * Most of what happens here is part of updating any block, not just a + * PIN block, so we'll probably want to refactor once we get to the + * point where we need to update key blocks too. */ static hal_error_t update_pin_block(const unsigned b1, flash_block_t *block, const flash_pin_block_t * const new_data) { - if (block == NULL || new_data == NULL || block_get_type(block) != BLOCK_TYPE_PINBLK) + if (block == NULL || new_data == NULL || block_get_type(block) != BLOCK_TYPE_PIN) return HAL_ERROR_IMPOSSIBLE; if (db.ksi.used == db.ksi.size) @@ -1052,9 +1144,10 @@ static hal_error_t update_pin_block(const unsigned b1, if ((err = block_write(b2, block)) != HAL_OK) return err; + int hint = 0; unsigned b3; - if ((err = hal_ks_index_replace(&db.ksi, &pin_uuid, &b3)) != HAL_OK) + if ((err = hal_ks_index_replace(&db.ksi, &pin_uuid, 0, &b3, &hint)) != HAL_OK) return err; if (b2 != b3) -- cgit v1.2.3