/* sqlite3_rekey
** Given a database, this will reencrypt the database using a new key.
** There are two possible modes of operation. The first is rekeying
** an existing database that was not previously encrypted. The second
** is to change the key on an existing database.
**
** The proposed logic for this function follows:
** 1. Determine if there is already a key present
** 2. If there is NOT already a key present, create one and attach a codec (key would be null)
** 3. Initialize a ctx->rekey parameter of the codec
**
** Note: this will require modifications to the sqlite3Codec to support rekey
**
*/
int sqlite3_rekey(sqlite3 *db, const void *pKey, int nKey) {
CODEC_TRACE(("sqlite3_rekey: entered db=%d pKey=%s, nKey=%d\n", db, pKey, nKey));
activate_openssl();
if(db && pKey && nKey) {
struct Db *pDb = &db->aDb[0];
CODEC_TRACE(("sqlite3_rekey: database pDb=%d\n", pDb));
if(pDb->pBt) {
codec_ctx *ctx;
int rc, page_count;
Pgno pgno;
PgHdr *page;
Pager *pPager = pDb->pBt->pBt->pPager;
sqlite3pager_get_codec(pDb->pBt->pBt->pPager, (void **) &ctx);
if(ctx == NULL) {
CODEC_TRACE(("sqlite3_rekey: no codec attached to db, attaching now\n"));
/* there was no codec attached to this database,so attach one now with a null password */
sqlite3CodecAttach(db, 0, pKey, nKey);
sqlite3pager_get_codec(pDb->pBt->pBt->pPager, (void **) &ctx);
/* prepare this setup as if it had already been initialized */
RAND_pseudo_bytes(ctx->kdf_salt, ctx->kdf_salt_sz);
ctx->read_ctx->key_sz = ctx->read_ctx->iv_sz = ctx->read_ctx->pass_sz = 0;
}
sqlite3_mutex_enter(db->mutex);
if(ctx->read_ctx->iv_sz != ctx->write_ctx->iv_sz) {
char *error;
CODEC_TRACE(("sqlite3_rekey: updating page size for iv_sz change from %d to %d\n", ctx->read_ctx->iv_sz, ctx->write_ctx->iv_sz));
db->nextPagesize = SQLITE_DEFAULT_PAGE_SIZE;
pDb->pBt->pBt->pageSizeFixed = 0; /* required for sqlite3BtreeSetPageSize to modify pagesize setting */
sqlite3BtreeSetPageSize(pDb->pBt, db->nextPagesize, EVP_MAX_IV_LENGTH, 0);
sqlite3RunVacuum(&error, db);
}
codec_set_pass_key(db, 0, pKey, nKey, 1);
ctx->mode_rekey = 1;
/* do stuff here to rewrite the database
** 1. Create a transaction on the database
** 2. Iterate through each page, reading it and then writing it.
** 3. If that goes ok then commit and put ctx->rekey into ctx->key
** note: don't deallocate rekey since it may be used in a subsequent iteration
*/
rc = sqlite3BtreeBeginTrans(pDb->pBt, 1); /* begin write transaction */
sqlite3PagerPagecount(pPager, &page_count);
for(pgno = 1; rc == SQLITE_OK && pgno <= page_count; pgno++) { /* pgno's start at 1 see pager.c:pagerAcquire */
if(!sqlite3pager_is_mj_pgno(pPager, pgno)) { /* skip this page (see pager.c:pagerAcquire for reasoning) */
rc = sqlite3PagerGet(pPager, pgno, &page);
if(rc == SQLITE_OK) { /* write page see pager_incr_changecounter for example */
rc = sqlite3PagerWrite(page);
//printf("sqlite3PagerWrite(%d)\n", pgno);
if(rc == SQLITE_OK) {
sqlite3PagerUnref(page);
}
}
}
}
/* if commit was successful commit and copy the rekey data to current key, else rollback to release locks */
if(rc == SQLITE_OK) {
CODEC_TRACE(("sqlite3_rekey: committing\n"));
db->nextPagesize = SQLITE_DEFAULT_PAGE_SIZE;
rc = sqlite3BtreeCommit(pDb->pBt);
cipher_ctx_copy(ctx->read_ctx, ctx->write_ctx);
} else {
CODEC_TRACE(("sqlite3_rekey: rollback\n"));
sqlite3BtreeRollback(pDb->pBt);
}
ctx->mode_rekey = 0;
sqlite3_mutex_leave(db->mutex);
}
return SQLITE_OK;
}
return SQLITE_ERROR;
}
/* sqlite3_rekey_v2
** Given a database, this will reencrypt the database using a new key.
** There is only one possible modes of operation - to encrypt a database
** that is already encrpyted. If the database is not already encrypted
** this should do nothing
** The proposed logic for this function follows:
** 1. Determine if the database is already encryptped
** 2. If there is NOT already a key present do nothing
** 3. If there is a key present, re-encrypt the database with the new key
*/
int sqlite3_rekey_v2(sqlite3 *db, const char *zDb, const void *pKey, int nKey) {
CODEC_TRACE(("sqlite3_rekey_v2: entered db=%p zDb=%s pKey=%s, nKey=%d\n", db, zDb, (char *)pKey, nKey));
if(db && pKey && nKey) {
int db_index = sqlcipher_find_db_index(db, zDb);
struct Db *pDb = &db->aDb[db_index];
CODEC_TRACE(("sqlite3_rekey_v2: database pDb=%p db_index:%d\n", pDb, db_index));
if(pDb->pBt) {
codec_ctx *ctx;
int rc, page_count;
Pgno pgno;
PgHdr *page;
Pager *pPager = pDb->pBt->pBt->pPager;
sqlite3pager_get_codec(pDb->pBt->pBt->pPager, (void **) &ctx);
if(ctx == NULL) {
/* there was no codec attached to this database, so this should do nothing! */
CODEC_TRACE(("sqlite3_rekey_v2: no codec attached to db, exiting\n"));
return SQLITE_OK;
}
sqlite3_mutex_enter(db->mutex);
codec_set_pass_key(db, db_index, pKey, nKey, CIPHER_WRITE_CTX);
/* do stuff here to rewrite the database
** 1. Create a transaction on the database
** 2. Iterate through each page, reading it and then writing it.
** 3. If that goes ok then commit and put ctx->rekey into ctx->key
** note: don't deallocate rekey since it may be used in a subsequent iteration
*/
rc = sqlite3BtreeBeginTrans(pDb->pBt, 1); /* begin write transaction */
sqlite3PagerPagecount(pPager, &page_count);
for(pgno = 1; rc == SQLITE_OK && pgno <= (unsigned int)page_count; pgno++) { /* pgno's start at 1 see pager.c:pagerAcquire */
if(!sqlite3pager_is_mj_pgno(pPager, pgno)) { /* skip this page (see pager.c:pagerAcquire for reasoning) */
rc = sqlite3PagerGet(pPager, pgno, &page);
if(rc == SQLITE_OK) { /* write page see pager_incr_changecounter for example */
rc = sqlite3PagerWrite(page);
if(rc == SQLITE_OK) {
sqlite3PagerUnref(page);
} else {
CODEC_TRACE(("sqlite3_rekey_v2: error %d occurred writing page %d\n", rc, pgno));
}
} else {
CODEC_TRACE(("sqlite3_rekey_v2: error %d occurred getting page %d\n", rc, pgno));
}
}
}
/* if commit was successful commit and copy the rekey data to current key, else rollback to release locks */
if(rc == SQLITE_OK) {
CODEC_TRACE(("sqlite3_rekey_v2: committing\n"));
rc = sqlite3BtreeCommit(pDb->pBt);
sqlcipher_codec_key_copy(ctx, CIPHER_WRITE_CTX);
} else {
CODEC_TRACE(("sqlite3_rekey_v2: rollback\n"));
sqlite3BtreeRollback(pDb->pBt, SQLITE_ABORT_ROLLBACK);
}
sqlite3_mutex_leave(db->mutex);
}
return SQLITE_OK;
}
return SQLITE_ERROR;
}
int sqlite3CodecAttach(sqlite3* db, int nDb, const void *zKey, int nKey) {
struct Db *pDb = &db->aDb[nDb];
CODEC_TRACE(("sqlite3CodecAttach: entered nDb=%d zKey=%s, nKey=%d\n", nDb, zKey, nKey));
activate_openssl();
if(nKey && zKey && pDb->pBt) {
codec_ctx *ctx;
int rc;
Pager *pPager = pDb->pBt->pBt->pPager;
sqlite3_file *fd;
ctx = sqlite3Malloc(sizeof(codec_ctx));
if(ctx == NULL) return SQLITE_NOMEM;
memset(ctx, 0, sizeof(codec_ctx)); /* initialize all pointers and values to 0 */
ctx->pBt = pDb->pBt; /* assign pointer to database btree structure */
if((rc = cipher_ctx_init(&ctx->read_ctx)) != SQLITE_OK) return rc;
if((rc = cipher_ctx_init(&ctx->write_ctx)) != SQLITE_OK) return rc;
/* pre-allocate a page buffer of PageSize bytes. This will
be used as a persistent buffer for encryption and decryption
operations to avoid overhead of multiple memory allocations*/
ctx->buffer = sqlite3Malloc(SQLITE_DEFAULT_PAGE_SIZE);
if(ctx->buffer == NULL) return SQLITE_NOMEM;
/* allocate space for salt data. Then read the first 16 bytes
directly off the database file. This is the salt for the
key derivation function. If we get a short read allocate
a new random salt value */
ctx->kdf_salt_sz = FILE_HEADER_SZ;
ctx->kdf_salt = sqlite3Malloc(ctx->kdf_salt_sz);
if(ctx->kdf_salt == NULL) return SQLITE_NOMEM;
fd = sqlite3Pager_get_fd(pPager);
if(fd == NULL || sqlite3OsRead(fd, ctx->kdf_salt, FILE_HEADER_SZ, 0) != SQLITE_OK) {
/* if unable to read the bytes, generate random salt */
RAND_pseudo_bytes(ctx->kdf_salt, FILE_HEADER_SZ);
}
sqlite3pager_sqlite3PagerSetCodec(sqlite3BtreePager(pDb->pBt), sqlite3Codec, NULL, sqlite3FreeCodecArg, (void *) ctx);
codec_set_cipher_name(db, nDb, CIPHER, 0);
codec_set_kdf_iter(db, nDb, PBKDF2_ITER, 0);
codec_set_pass_key(db, nDb, zKey, nKey, 0);
cipher_ctx_copy(ctx->write_ctx, ctx->read_ctx);
sqlite3_mutex_enter(db->mutex);
/* Always overwrite page size and set to the default because the first page of the database
in encrypted and thus sqlite can't effectively determine the pagesize. this causes an issue in
cases where bytes 16 & 17 of the page header are a power of 2 as reported by John Lehman
Note: before forcing the page size we need to force pageSizeFixed to 0, else
sqliteBtreeSetPageSize will block the change
*/
pDb->pBt->pBt->pageSizeFixed = 0;
sqlite3BtreeSetPageSize(ctx->pBt, SQLITE_DEFAULT_PAGE_SIZE, EVP_MAX_IV_LENGTH, 0);
/* if fd is null, then this is an in-memory database and
we dont' want to overwrite the AutoVacuum settings
if not null, then set to the default */
if(fd != NULL) {
sqlite3BtreeSetAutoVacuum(ctx->pBt, SQLITE_DEFAULT_AUTOVACUUM);
}
sqlite3_mutex_leave(db->mutex);
}
return SQLITE_OK;
}
