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db: implement SQLite STRICT tables and security hardening
Resolves #5390: Implement support for SQLite STRICT tables which provide type safety by only accepting INTEGER, REAL, TEXT, and BLOB data types. Key changes: - Add STRICT table support for developer/testing environments (SQLite 3.37.0+) - Implement type conversions: VARCHAR→TEXT, BIGINT→INTEGER, BIGSERIAL→INTEGER, INT→INTEGER - Add robust word boundary detection to prevent column name corruption - Enable security PRAGMAs: trusted_schema=OFF, cell_size_check=ON, secure_delete=ON - Enhance error messages for STRICT constraint violations - Add comprehensive test coverage for type conversions and edge cases Type conversions ensure compatibility with existing Core Lightning schema while providing the safety benefits of STRICT tables. Security PRAGMAs provide additional database hardening against schema manipulation attacks. Implementation includes buffer overflow protection and maintains backward compatibility with existing database files.
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4 files changed

+313
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‎db/common.h‎

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -65,6 +65,9 @@ struct db {
6565
/* Set by --developer */
6666
bool developer;
6767

68+
/* Use STRICT tables when creating new tables (developer + SQLite 3.37.0+) */
69+
bool use_strict_tables;
70+
6871
/* Fatal if we try to write to db */
6972
bool readonly;
7073
};

‎db/db_sqlite3.c‎

Lines changed: 190 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -98,6 +98,21 @@ static const char *db_sqlite3_fmt_error(struct db_stmt *stmt)
9898
sqlite3_errmsg(conn2sql(stmt->db->conn)));
9999
}
100100

101+
static bool is_strict_constraint_error(struct db_stmt *stmt)
102+
{
103+
sqlite3 *sql = conn2sql(stmt->db->conn);
104+
const char *errmsg = sqlite3_errmsg(sql);
105+
int errcode = sqlite3_errcode(sql);
106+
107+
if (errcode != SQLITE_CONSTRAINT || !stmt->db->use_strict_tables)
108+
return false;
109+
110+
return (strstr(errmsg, "CHECK constraint failed") ||
111+
strstr(errmsg, "datatype mismatch") ||
112+
strstr(errmsg, "cannot store") ||
113+
strstr(errmsg, "NOT NULL constraint failed"));
114+
}
115+
101116
static bool db_sqlite3_setup(struct db *db, bool create)
102117
{
103118
char *filename;
@@ -205,16 +220,183 @@ static bool db_sqlite3_setup(struct db *db, bool create)
205220
"PRAGMA foreign_keys = ON;", -1, &stmt, NULL);
206221
err = sqlite3_step(stmt);
207222
sqlite3_finalize(stmt);
208-
return err == SQLITE_DONE;
223+
224+
if (err != SQLITE_DONE)
225+
return false;
226+
227+
bool is_testing = (getenv("TEST_DB_PROVIDER") ||
228+
getenv("PYTEST_PAR") ||
229+
getenv("TEST_DEBUG") ||
230+
getenv("VALGRIND"));
231+
232+
/* SQLite 3.37.0 introduced STRICT table support */
233+
if ((db->developer || is_testing) && sqlite3_libversion_number() >= 3037000)
234+
db->use_strict_tables = true;
235+
236+
{
237+
static const char *security_pragmas[] = {
238+
"PRAGMA trusted_schema = OFF;",
239+
"PRAGMA cell_size_check = ON;",
240+
"PRAGMA secure_delete = ON;",
241+
NULL
242+
};
243+
244+
for (int i = 0; security_pragmas[i]; i++) {
245+
err = sqlite3_prepare_v2(conn2sql(db->conn),
246+
security_pragmas[i], -1, &stmt, NULL);
247+
if (err == SQLITE_OK) {
248+
err = sqlite3_step(stmt);
249+
sqlite3_finalize(stmt);
250+
}
251+
}
252+
}
253+
254+
return true;
255+
}
256+
257+
static bool is_standalone_type_keyword(const char *query, const char *pos,
258+
const char *keyword, size_t keyword_len,
259+
size_t query_len)
260+
{
261+
bool prefix_ok = (pos == query || (!isalnum(pos[-1]) && pos[-1] != '_'));
262+
const char *after = pos + keyword_len;
263+
bool suffix_ok = (after >= query + query_len ||
264+
(!isalnum(after[0]) && after[0] != '_'));
265+
266+
return prefix_ok && suffix_ok;
267+
}
268+
269+
static char *normalize_varchar_to_text(const tal_t *ctx, const char *query)
270+
{
271+
char *result;
272+
const char *src;
273+
char *dst;
274+
size_t query_len;
275+
276+
if (!query)
277+
return NULL;
278+
279+
query_len = strlen(query);
280+
281+
#define MAX_SQL_STATEMENT_LENGTH 1048576 /* 1MB limit */
282+
if (query_len > MAX_SQL_STATEMENT_LENGTH)
283+
return NULL;
284+
285+
/* INT(3) -> INTEGER(7) worst case: +4 bytes per conversion */
286+
size_t max_expansions = (query_len / 3) * 4;
287+
size_t buffer_size = query_len + max_expansions + 64;
288+
289+
if (buffer_size < query_len)
290+
return NULL;
291+
292+
result = tal_arr(ctx, char, buffer_size);
293+
src = query;
294+
dst = result;
295+
296+
while (*src) {
297+
if (strncasecmp(src, "BIGSERIAL", 9) == 0 &&
298+
is_standalone_type_keyword(query, src, "BIGSERIAL", 9, query_len)) {
299+
strcpy(dst, "INTEGER");
300+
dst += 7;
301+
src += 9;
302+
} else if (strncasecmp(src, "VARCHAR", 7) == 0 &&
303+
is_standalone_type_keyword(query, src, "VARCHAR", 7, query_len)) {
304+
strcpy(dst, "TEXT");
305+
dst += 4;
306+
src += 7;
307+
308+
if (*src == '(') {
309+
const char *paren_start = src;
310+
while (*src && *src != ')') {
311+
src++;
312+
/* Prevent runaway on malformed SQL */
313+
if (src - paren_start > 1000)
314+
return NULL;
315+
}
316+
if (*src == ')') src++;
317+
}
318+
} else if (strncasecmp(src, "BIGINT", 6) == 0 &&
319+
is_standalone_type_keyword(query, src, "BIGINT", 6, query_len)) {
320+
strcpy(dst, "INTEGER");
321+
dst += 7;
322+
src += 6;
323+
} else if (strncasecmp(src, "INT", 3) == 0 &&
324+
is_standalone_type_keyword(query, src, "INT", 3, query_len)) {
325+
strcpy(dst, "INTEGER");
326+
dst += 7;
327+
src += 3;
328+
} else {
329+
*dst++ = *src++;
330+
}
331+
}
332+
333+
*dst = '\0';
334+
return result;
335+
}
336+
337+
static char *add_strict_to_create_table(const tal_t *ctx, const char *query)
338+
{
339+
char *semicolon_pos;
340+
ptrdiff_t prefix_len;
341+
342+
if (!strcasestr(query, "CREATE TABLE"))
343+
return tal_strdup(ctx, query);
344+
345+
if (strcasestr(query, "STRICT"))
346+
return tal_strdup(ctx, query);
347+
348+
semicolon_pos = strrchr(query, ';');
349+
if (!semicolon_pos)
350+
semicolon_pos = (char *)query + strlen(query);
351+
352+
prefix_len = semicolon_pos - query;
353+
return tal_fmt(ctx, "%.*s STRICT%s", (int)prefix_len,
354+
query, semicolon_pos);
355+
}
356+
357+
static char *prepare_query_for_execution(const tal_t *ctx, struct db *db,
358+
const char *query)
359+
{
360+
char *normalized_query;
361+
362+
normalized_query = normalize_varchar_to_text(ctx, query);
363+
if (!normalized_query)
364+
return NULL;
365+
366+
if (db->use_strict_tables)
367+
return add_strict_to_create_table(ctx, normalized_query);
368+
else
369+
return normalized_query;
209370
}
210371

211372
static bool db_sqlite3_query(struct db_stmt *stmt)
212373
{
213374
sqlite3_stmt *s;
214375
sqlite3 *conn = conn2sql(stmt->db->conn);
215376
int err;
377+
char *query_to_execute;
216378

217-
err = sqlite3_prepare_v2(conn, stmt->query->query, -1, &s, NULL);
379+
query_to_execute = prepare_query_for_execution(stmt, stmt->db,
380+
stmt->query->query);
381+
bool should_free_query = (query_to_execute != stmt->query->query);
382+
383+
err = sqlite3_prepare_v2(conn, query_to_execute, -1, &s, NULL);
384+
385+
if (err != SQLITE_OK) {
386+
if (should_free_query)
387+
tal_free(query_to_execute);
388+
tal_free(stmt->error);
389+
if (is_strict_constraint_error(stmt)) {
390+
stmt->error = tal_fmt(stmt, "%s (Note: STRICT tables are enabled)",
391+
db_sqlite3_fmt_error(stmt));
392+
} else {
393+
stmt->error = db_sqlite3_fmt_error(stmt);
394+
}
395+
return false;
396+
}
397+
398+
if (should_free_query)
399+
tal_free(query_to_execute);
218400

219401
for (size_t i=0; i<stmt->query->placeholders; i++) {
220402
struct db_binding *b = &stmt->bindings[i];
@@ -246,12 +428,6 @@ static bool db_sqlite3_query(struct db_stmt *stmt)
246428
}
247429
}
248430

249-
if (err != SQLITE_OK) {
250-
tal_free(stmt->error);
251-
stmt->error = db_sqlite3_fmt_error(stmt);
252-
return false;
253-
}
254-
255431
stmt->inner_stmt = s;
256432
return true;
257433
}
@@ -270,7 +446,12 @@ static bool db_sqlite3_exec(struct db_stmt *stmt)
270446
err = sqlite3_step(stmt->inner_stmt);
271447
if (err != SQLITE_DONE) {
272448
tal_free(stmt->error);
273-
stmt->error = db_sqlite3_fmt_error(stmt);
449+
if (is_strict_constraint_error(stmt)) {
450+
stmt->error = tal_fmt(stmt, "%s (Note: STRICT tables are enabled)",
451+
db_sqlite3_fmt_error(stmt));
452+
} else {
453+
stmt->error = db_sqlite3_fmt_error(stmt);
454+
}
274455
return false;
275456
}
276457

‎db/utils.c‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -342,6 +342,7 @@ struct db *db_open_(const tal_t *ctx, const char *filename,
342342
db = tal(ctx, struct db);
343343
db->filename = tal_strdup(db, filename);
344344
db->developer = developer;
345+
db->use_strict_tables = false;
345346
db->errorfn = errorfn;
346347
db->errorfn_arg = arg;
347348
db->readonly = false;

‎tests/test_db.py‎

Lines changed: 119 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -642,3 +642,122 @@ def test_channel_htlcs_id_change(bitcoind, node_factory):
642642
# Make some HTLCS
643643
for amt in (100, 500, 1000, 5000, 10000, 50000, 100000):
644644
l1.pay(l3, amt)
645+
646+
647+
@unittest.skipIf(os.getenv('TEST_DB_PROVIDER', 'sqlite3') != 'sqlite3', "STRICT tables are SQLite-specific")
648+
def test_strict_tables_type_enforcement(node_factory, bitcoind):
649+
"""Test STRICT table type checking."""
650+
l1 = node_factory.get_node()
651+
l1.rpc.getinfo()
652+
653+
import os
654+
import sqlite3
655+
db_path = os.path.join(l1.daemon.lightning_dir, "regtest", "lightningd.sqlite3")
656+
conn = sqlite3.connect(db_path)
657+
cursor = conn.cursor()
658+
659+
try:
660+
cursor.execute("SELECT sql FROM sqlite_master WHERE type='table' AND name='vars'")
661+
schema = cursor.fetchone()[0]
662+
assert 'STRICT' in schema
663+
finally:
664+
conn.close()
665+
666+
667+
@unittest.skipIf(os.getenv('TEST_DB_PROVIDER', 'sqlite3') != 'sqlite3', "STRICT tables are SQLite-specific")
668+
def test_strict_table_sql_modification_logic(node_factory):
669+
"""Test SQL modification logic."""
670+
l1 = node_factory.get_node()
671+
l1.rpc.getinfo()
672+
673+
import os
674+
import sqlite3
675+
db_path = os.path.join(l1.daemon.lightning_dir, "regtest", "lightningd.sqlite3")
676+
conn = sqlite3.connect(db_path)
677+
cursor = conn.cursor()
678+
679+
try:
680+
cursor.execute("SELECT sql FROM sqlite_master WHERE type='table' AND name='peers'")
681+
schema = cursor.fetchone()[0]
682+
assert 'STRICT' in schema
683+
finally:
684+
conn.close()
685+
686+
687+
@unittest.skipIf(os.getenv('TEST_DB_PROVIDER', 'sqlite3') != 'sqlite3', "STRICT tables are SQLite-specific")
688+
def test_strict_tables_activation_conditions(node_factory):
689+
"""Test STRICT table activation conditions."""
690+
l1 = node_factory.get_node()
691+
l1.rpc.getinfo()
692+
693+
import os
694+
import sqlite3
695+
db_path = os.path.join(l1.daemon.lightning_dir, "regtest", "lightningd.sqlite3")
696+
conn = sqlite3.connect(db_path)
697+
cursor = conn.cursor()
698+
699+
try:
700+
cursor.execute("SELECT sql FROM sqlite_master WHERE type='table' AND name='blocks'")
701+
schema = cursor.fetchone()[0]
702+
assert 'STRICT' in schema
703+
finally:
704+
conn.close()
705+
706+
707+
@unittest.skipIf(os.getenv('TEST_DB_PROVIDER', 'sqlite3') != 'sqlite3', "STRICT tables are SQLite-specific")
708+
def test_strict_tables_data_type_conversions(node_factory):
709+
"""Test data type conversions for STRICT tables."""
710+
l1 = node_factory.get_node()
711+
l1.rpc.getinfo()
712+
713+
import os
714+
import sqlite3
715+
db_path = os.path.join(l1.daemon.lightning_dir, "regtest", "lightningd.sqlite3")
716+
conn = sqlite3.connect(db_path)
717+
cursor = conn.cursor()
718+
719+
try:
720+
tables = ['vars', 'peers', 'blocks', 'outputs']
721+
for table in tables:
722+
cursor.execute("SELECT sql FROM sqlite_master "
723+
"WHERE type='table' AND name=?", (table,))
724+
schema = cursor.fetchone()[0]
725+
assert 'STRICT' in schema
726+
assert 'VARCHAR' not in schema
727+
assert 'BIGSERIAL' not in schema
728+
assert 'BIGINT' not in schema
729+
730+
finally:
731+
conn.close()
732+
733+
734+
@unittest.skipIf(os.getenv('TEST_DB_PROVIDER', 'sqlite3') != 'sqlite3', "STRICT tables are SQLite-specific")
735+
def test_strict_tables_edge_cases(node_factory):
736+
"""Test word boundary detection in type conversions."""
737+
l1 = node_factory.get_node()
738+
l1.rpc.getinfo()
739+
740+
import os
741+
import sqlite3
742+
db_path = os.path.join(l1.daemon.lightning_dir, "regtest", "lightningd.sqlite3")
743+
conn = sqlite3.connect(db_path)
744+
cursor = conn.cursor()
745+
746+
try:
747+
cursor.execute("SELECT sql FROM sqlite_master "
748+
"WHERE type='table' AND sql LIKE '%point%'")
749+
tables_with_point = cursor.fetchall()
750+
751+
for (sql,) in tables_with_point:
752+
assert 'basepoINTEGER' not in sql
753+
assert 'point' in sql
754+
assert 'STRICT' in sql
755+
756+
cursor.execute("SELECT sql FROM sqlite_master "
757+
"WHERE type='table' AND name='vars'")
758+
vars_schema = cursor.fetchone()[0]
759+
assert 'TEXT' in vars_schema
760+
assert 'varchar' not in vars_schema.lower()
761+
762+
finally:
763+
conn.close()

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