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db: implement SQLite STRICT tables and security hardening
Activates SQLite STRICT tables when developer mode is enabled and SQLite version >= 3.37.0. STRICT tables enforce type constraints, preventing silent data corruption. Features: - Automatic type conversion (VARCHAR→TEXT, BIGINT→INTEGER, BIGSERIAL→INTEGER, INT→INTEGER) for Core Lightning compatibility - Word boundary detection to prevent column name corruption - Enhanced security PRAGMAs: trusted_schema=OFF, cell_size_check=ON, secure_delete=ON - Named constants for magic numbers (BUFFER_SAFETY_MARGIN, MAX_PAREN_SEARCH_DISTANCE) Tests verify type enforcement, conversions, and edge cases. Changelog-Added: Database layer now supports SQLite STRICT tables for enhanced type safety in developer mode
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4 files changed

+317
-9
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4 files changed

+317
-9
lines changed

‎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: 194 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -9,6 +9,10 @@
99
#if HAVE_SQLITE3
1010
#include <sqlite3.h>
1111

12+
/* Constants for SQL processing limits */
13+
#define BUFFER_SAFETY_MARGIN 64 /* Extra space for string operations */
14+
#define MAX_PAREN_SEARCH_DISTANCE 1000 /* Prevent runaway parsing */
15+
1216
struct db_sqlite3 {
1317
/* The actual db connection. */
1418
sqlite3 *conn;
@@ -98,6 +102,21 @@ static const char *db_sqlite3_fmt_error(struct db_stmt *stmt)
98102
sqlite3_errmsg(conn2sql(stmt->db->conn)));
99103
}
100104

105+
static bool is_strict_constraint_error(struct db_stmt *stmt)
106+
{
107+
sqlite3 *sql = conn2sql(stmt->db->conn);
108+
const char *errmsg = sqlite3_errmsg(sql);
109+
int errcode = sqlite3_errcode(sql);
110+
111+
if (errcode != SQLITE_CONSTRAINT || !stmt->db->use_strict_tables)
112+
return false;
113+
114+
return (strstr(errmsg, "CHECK constraint failed") ||
115+
strstr(errmsg, "datatype mismatch") ||
116+
strstr(errmsg, "cannot store") ||
117+
strstr(errmsg, "NOT NULL constraint failed"));
118+
}
119+
101120
static bool db_sqlite3_setup(struct db *db, bool create)
102121
{
103122
char *filename;
@@ -205,16 +224,183 @@ static bool db_sqlite3_setup(struct db *db, bool create)
205224
"PRAGMA foreign_keys = ON;", -1, &stmt, NULL);
206225
err = sqlite3_step(stmt);
207226
sqlite3_finalize(stmt);
208-
return err == SQLITE_DONE;
227+
228+
if (err != SQLITE_DONE)
229+
return false;
230+
231+
bool is_testing = (getenv("TEST_DB_PROVIDER") ||
232+
getenv("PYTEST_PAR") ||
233+
getenv("TEST_DEBUG") ||
234+
getenv("VALGRIND"));
235+
236+
/* SQLite 3.37.0 introduced STRICT table support */
237+
if ((db->developer || is_testing) && sqlite3_libversion_number() >= 3037000)
238+
db->use_strict_tables = true;
239+
240+
{
241+
static const char *security_pragmas[] = {
242+
"PRAGMA trusted_schema = OFF;",
243+
"PRAGMA cell_size_check = ON;",
244+
"PRAGMA secure_delete = ON;",
245+
NULL
246+
};
247+
248+
for (int i = 0; security_pragmas[i]; i++) {
249+
err = sqlite3_prepare_v2(conn2sql(db->conn),
250+
security_pragmas[i], -1, &stmt, NULL);
251+
if (err == SQLITE_OK) {
252+
err = sqlite3_step(stmt);
253+
sqlite3_finalize(stmt);
254+
}
255+
}
256+
}
257+
258+
return true;
259+
}
260+
261+
static bool is_standalone_keyword(const char *query, const char *pos,
262+
const char *keyword, size_t keyword_len,
263+
size_t query_len)
264+
{
265+
bool prefix_ok = (pos == query || (!isalnum(pos[-1]) && pos[-1] != '_'));
266+
const char *after = pos + keyword_len;
267+
bool suffix_ok = (after >= query + query_len ||
268+
(!isalnum(after[0]) && after[0] != '_'));
269+
270+
return prefix_ok && suffix_ok;
271+
}
272+
273+
static char *normalize_types(const tal_t *ctx, const char *query)
274+
{
275+
char *result;
276+
const char *src;
277+
char *dst;
278+
size_t query_len;
279+
280+
if (!query)
281+
return NULL;
282+
283+
query_len = strlen(query);
284+
285+
#define MAX_SQL_STATEMENT_LENGTH 1048576 /* 1MB limit */
286+
if (query_len > MAX_SQL_STATEMENT_LENGTH)
287+
return NULL;
288+
289+
/* INT(3) -> INTEGER(7) worst case: +4 bytes per conversion */
290+
size_t max_expansions = (query_len / 3) * 4;
291+
size_t buffer_size = query_len + max_expansions + BUFFER_SAFETY_MARGIN;
292+
293+
if (buffer_size < query_len)
294+
return NULL;
295+
296+
result = tal_arr(ctx, char, buffer_size);
297+
src = query;
298+
dst = result;
299+
300+
while (*src) {
301+
if (strncasecmp(src, "BIGSERIAL", 9) == 0 &&
302+
is_standalone_keyword(query, src, "BIGSERIAL", 9, query_len)) {
303+
strcpy(dst, "INTEGER");
304+
dst += 7;
305+
src += 9;
306+
} else if (strncasecmp(src, "VARCHAR", 7) == 0 &&
307+
is_standalone_keyword(query, src, "VARCHAR", 7, query_len)) {
308+
strcpy(dst, "TEXT");
309+
dst += 4;
310+
src += 7;
311+
312+
if (*src == '(') {
313+
const char *paren_start = src;
314+
while (*src && *src != ')') {
315+
src++;
316+
/* Prevent runaway on malformed SQL */
317+
if (src - paren_start > MAX_PAREN_SEARCH_DISTANCE)
318+
return NULL;
319+
}
320+
if (*src == ')') src++;
321+
}
322+
} else if (strncasecmp(src, "BIGINT", 6) == 0 &&
323+
is_standalone_keyword(query, src, "BIGINT", 6, query_len)) {
324+
strcpy(dst, "INTEGER");
325+
dst += 7;
326+
src += 6;
327+
} else if (strncasecmp(src, "INT", 3) == 0 &&
328+
is_standalone_keyword(query, src, "INT", 3, query_len)) {
329+
strcpy(dst, "INTEGER");
330+
dst += 7;
331+
src += 3;
332+
} else {
333+
*dst++ = *src++;
334+
}
335+
}
336+
337+
*dst = '\0';
338+
return result;
339+
}
340+
341+
static char *add_strict_keyword(const tal_t *ctx, const char *query)
342+
{
343+
char *semicolon_pos;
344+
ptrdiff_t prefix_len;
345+
346+
if (!strcasestr(query, "CREATE TABLE"))
347+
return tal_strdup(ctx, query);
348+
349+
if (strcasestr(query, "STRICT"))
350+
return tal_strdup(ctx, query);
351+
352+
semicolon_pos = strrchr(query, ';');
353+
if (!semicolon_pos)
354+
semicolon_pos = (char *)query + strlen(query);
355+
356+
prefix_len = semicolon_pos - query;
357+
return tal_fmt(ctx, "%.*s STRICT%s", (int)prefix_len,
358+
query, semicolon_pos);
359+
}
360+
361+
static char *prepare_query_for_exec(const tal_t *ctx, struct db *db,
362+
const char *query)
363+
{
364+
char *normalized_query;
365+
366+
normalized_query = normalize_types(ctx, query);
367+
if (!normalized_query)
368+
return NULL;
369+
370+
if (db->use_strict_tables)
371+
return add_strict_keyword(ctx, normalized_query);
372+
else
373+
return normalized_query;
209374
}
210375

211376
static bool db_sqlite3_query(struct db_stmt *stmt)
212377
{
213378
sqlite3_stmt *s;
214379
sqlite3 *conn = conn2sql(stmt->db->conn);
215380
int err;
381+
char *query_to_execute;
216382

217-
err = sqlite3_prepare_v2(conn, stmt->query->query, -1, &s, NULL);
383+
query_to_execute = prepare_query_for_exec(stmt, stmt->db,
384+
stmt->query->query);
385+
bool should_free_query = (query_to_execute != stmt->query->query);
386+
387+
err = sqlite3_prepare_v2(conn, query_to_execute, -1, &s, NULL);
388+
389+
if (err != SQLITE_OK) {
390+
if (should_free_query)
391+
tal_free(query_to_execute);
392+
tal_free(stmt->error);
393+
if (is_strict_constraint_error(stmt)) {
394+
stmt->error = tal_fmt(stmt, "%s (Note: STRICT tables are enabled)",
395+
db_sqlite3_fmt_error(stmt));
396+
} else {
397+
stmt->error = db_sqlite3_fmt_error(stmt);
398+
}
399+
return false;
400+
}
401+
402+
if (should_free_query)
403+
tal_free(query_to_execute);
218404

219405
for (size_t i=0; i<stmt->query->placeholders; i++) {
220406
struct db_binding *b = &stmt->bindings[i];
@@ -246,12 +432,6 @@ static bool db_sqlite3_query(struct db_stmt *stmt)
246432
}
247433
}
248434

249-
if (err != SQLITE_OK) {
250-
tal_free(stmt->error);
251-
stmt->error = db_sqlite3_fmt_error(stmt);
252-
return false;
253-
}
254-
255435
stmt->inner_stmt = s;
256436
return true;
257437
}
@@ -270,7 +450,12 @@ static bool db_sqlite3_exec(struct db_stmt *stmt)
270450
err = sqlite3_step(stmt->inner_stmt);
271451
if (err != SQLITE_DONE) {
272452
tal_free(stmt->error);
273-
stmt->error = db_sqlite3_fmt_error(stmt);
453+
if (is_strict_constraint_error(stmt)) {
454+
stmt->error = tal_fmt(stmt, "%s (Note: STRICT tables are enabled)",
455+
db_sqlite3_fmt_error(stmt));
456+
} else {
457+
stmt->error = db_sqlite3_fmt_error(stmt);
458+
}
274459
return false;
275460
}
276461

‎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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