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MasahikoSawadabdrouvotAWS
MasahikoSawada
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bdrouvotAWS
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pg_logicalinspect: Fix possible crash when passing a directory path.
Previously, pg_logicalinspect functions were too trusting of their input and blindly passed it to SnapBuildRestoreSnapshot(). If the input pointed to a directory, the server could a PANIC error while attempting to fsync_fname() with isdir=false on a directory. This commit adds validation checks for input filenames and passes the LSN extracted from the filename to SnapBuildRestoreSnapshot() instead of the filename itself. It also adds regression tests for various input patterns and permission checks. Bug: #18828 Reported-by: Robins Tharakan <[email protected]> Co-authored-by: Bertrand Drouvot <[email protected]> Co-authored-by: Masahiko Sawada <[email protected]> Discussion: https://postgr.es/m/[email protected]
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-18
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6 files changed

+183
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‎contrib/pg_logicalinspect/Makefile

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -11,6 +11,7 @@ DATA = pg_logicalinspect--1.0.sql
1111

1212
EXTRA_INSTALL = contrib/test_decoding
1313

14+
REGRESS = pg_logicalinspect
1415
ISOLATION = logical_inspect
1516

1617
ISOLATION_OPTS = --temp-config $(top_srcdir)/contrib/pg_logicalinspect/logicalinspect.conf

‎contrib/pg_logicalinspect/expected/pg_logicalinspect.out

Lines changed: 81 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,81 @@
1+
CREATE EXTENSION pg_logicalinspect;
2+
-- ===================================================================
3+
-- Tests for input validation
4+
-- ===================================================================
5+
SELECT pg_get_logical_snapshot_info('0-40796E18.foo');
6+
ERROR: invalid snapshot file name "0-40796E18.foo"
7+
SELECT pg_get_logical_snapshot_info('0--40796E18.snap');
8+
ERROR: invalid snapshot file name "0--40796E18.snap"
9+
SELECT pg_get_logical_snapshot_info('-1--40796E18.snap');
10+
ERROR: invalid snapshot file name "-1--40796E18.snap"
11+
SELECT pg_get_logical_snapshot_info('0/40796E18.foo.snap');
12+
ERROR: invalid snapshot file name "0/40796E18.foo.snap"
13+
SELECT pg_get_logical_snapshot_info('0/40796E18.snap');
14+
ERROR: invalid snapshot file name "0/40796E18.snap"
15+
SELECT pg_get_logical_snapshot_info('');
16+
ERROR: invalid snapshot file name ""
17+
SELECT pg_get_logical_snapshot_info(NULL);
18+
pg_get_logical_snapshot_info
19+
------------------------------
20+
21+
(1 row)
22+
23+
SELECT pg_get_logical_snapshot_info('../snapshots');
24+
ERROR: invalid snapshot file name "../snapshots"
25+
SELECT pg_get_logical_snapshot_info('../snapshots/0-40796E18.snap');
26+
ERROR: invalid snapshot file name "../snapshots/0-40796E18.snap"
27+
SELECT pg_get_logical_snapshot_meta('0-40796E18.foo');
28+
ERROR: invalid snapshot file name "0-40796E18.foo"
29+
SELECT pg_get_logical_snapshot_meta('0-40796E18.foo.snap');
30+
ERROR: invalid snapshot file name "0-40796E18.foo.snap"
31+
SELECT pg_get_logical_snapshot_meta('0/40796E18.snap');
32+
ERROR: invalid snapshot file name "0/40796E18.snap"
33+
SELECT pg_get_logical_snapshot_meta('');
34+
ERROR: invalid snapshot file name ""
35+
SELECT pg_get_logical_snapshot_meta(NULL);
36+
pg_get_logical_snapshot_meta
37+
------------------------------
38+
39+
(1 row)
40+
41+
SELECT pg_get_logical_snapshot_meta('../snapshots');
42+
ERROR: invalid snapshot file name "../snapshots"
43+
-- ===================================================================
44+
-- Tests for permissions
45+
-- ===================================================================
46+
CREATE ROLE regress_pg_logicalinspect;
47+
SELECT has_function_privilege('regress_pg_logicalinspect',
48+
'pg_get_logical_snapshot_info(text)', 'EXECUTE'); -- no
49+
has_function_privilege
50+
------------------------
51+
f
52+
(1 row)
53+
54+
SELECT has_function_privilege('regress_pg_logicalinspect',
55+
'pg_get_logical_snapshot_meta(text)', 'EXECUTE'); -- no
56+
has_function_privilege
57+
------------------------
58+
f
59+
(1 row)
60+
61+
-- Functions accessible by users with role pg_read_server_files.
62+
GRANT pg_read_server_files TO regress_pg_logicalinspect;
63+
SELECT has_function_privilege('regress_pg_logicalinspect',
64+
'pg_get_logical_snapshot_info(text)', 'EXECUTE'); -- yes
65+
has_function_privilege
66+
------------------------
67+
t
68+
(1 row)
69+
70+
SELECT has_function_privilege('regress_pg_logicalinspect',
71+
'pg_get_logical_snapshot_meta(text)', 'EXECUTE'); -- yes
72+
has_function_privilege
73+
------------------------
74+
t
75+
(1 row)
76+
77+
-- ===================================================================
78+
-- Clean up
79+
-- ===================================================================
80+
DROP ROLE regress_pg_logicalinspect;
81+
DROP EXTENSION pg_logicalinspect;

‎contrib/pg_logicalinspect/pg_logicalinspect.c

Lines changed: 45 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -48,6 +48,45 @@ get_snapbuild_state_desc(SnapBuildState state)
4848
return stateDesc;
4949
}
5050

51+
/*
52+
* Extract the LSN from the given serialized snapshot file name.
53+
*/
54+
static XLogRecPtr
55+
parse_snapshot_filename(const char *filename)
56+
{
57+
uint32 hi;
58+
uint32 lo;
59+
XLogRecPtr lsn;
60+
char tmpfname[MAXPGPATH];
61+
62+
/*
63+
* Extract the values to build the LSN.
64+
*
65+
* Note: Including ".snap" doesn't mean that sscanf() also does the format
66+
* check including the suffix. The subsequent check validates if the given
67+
* filename has the expected suffix.
68+
*/
69+
if (sscanf(filename, "%X-%X.snap", &hi, &lo) != 2)
70+
goto parse_error;
71+
72+
/*
73+
* Bring back the extracted LSN to the snapshot file format and compare it
74+
* to the given filename. This check strictly checks if the given filename
75+
* follows the format of the snapshot filename.
76+
*/
77+
sprintf(tmpfname, "%X-%X.snap", hi, lo);
78+
if (strcmp(tmpfname, filename) != 0)
79+
goto parse_error;
80+
81+
lsn = ((uint64) hi) << 32 | lo;
82+
83+
return lsn;
84+
85+
parse_error:
86+
ereport(ERROR,
87+
errmsg("invalid snapshot file name \"%s\"", filename));
88+
}
89+
5190
/*
5291
* Retrieve the logical snapshot file metadata.
5392
*/
@@ -60,20 +99,18 @@ pg_get_logical_snapshot_meta(PG_FUNCTION_ARGS)
6099
Datum values[PG_GET_LOGICAL_SNAPSHOT_META_COLS] = {0};
61100
bool nulls[PG_GET_LOGICAL_SNAPSHOT_META_COLS] = {0};
62101
TupleDesc tupdesc;
63-
char path[MAXPGPATH];
102+
XLogRecPtr lsn;
64103
int i = 0;
65104
text *filename_t = PG_GETARG_TEXT_PP(0);
66105

67106
/* Build a tuple descriptor for our result type */
68107
if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
69108
elog(ERROR, "return type must be a row type");
70109

71-
sprintf(path, "%s/%s",
72-
PG_LOGICAL_SNAPSHOTS_DIR,
73-
text_to_cstring(filename_t));
110+
lsn = parse_snapshot_filename(text_to_cstring(filename_t));
74111

75112
/* Validate and restore the snapshot to 'ondisk' */
76-
SnapBuildRestoreSnapshot(&ondisk, path, CurrentMemoryContext, false);
113+
SnapBuildRestoreSnapshot(&ondisk, lsn, CurrentMemoryContext, false);
77114

78115
values[i++] = UInt32GetDatum(ondisk.magic);
79116
values[i++] = Int64GetDatum((int64) ondisk.checksum);
@@ -97,20 +134,18 @@ pg_get_logical_snapshot_info(PG_FUNCTION_ARGS)
97134
Datum values[PG_GET_LOGICAL_SNAPSHOT_INFO_COLS] = {0};
98135
bool nulls[PG_GET_LOGICAL_SNAPSHOT_INFO_COLS] = {0};
99136
TupleDesc tupdesc;
100-
char path[MAXPGPATH];
137+
XLogRecPtr lsn;
101138
int i = 0;
102139
text *filename_t = PG_GETARG_TEXT_PP(0);
103140

104141
/* Build a tuple descriptor for our result type */
105142
if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
106143
elog(ERROR, "return type must be a row type");
107144

108-
sprintf(path, "%s/%s",
109-
PG_LOGICAL_SNAPSHOTS_DIR,
110-
text_to_cstring(filename_t));
145+
lsn = parse_snapshot_filename(text_to_cstring(filename_t));
111146

112147
/* Validate and restore the snapshot to 'ondisk' */
113-
SnapBuildRestoreSnapshot(&ondisk, path, CurrentMemoryContext, false);
148+
SnapBuildRestoreSnapshot(&ondisk, lsn, CurrentMemoryContext, false);
114149

115150
values[i++] = CStringGetTextDatum(get_snapbuild_state_desc(ondisk.builder.state));
116151
values[i++] = TransactionIdGetDatum(ondisk.builder.xmin);

‎contrib/pg_logicalinspect/sql/pg_logicalinspect.sql

Lines changed: 48 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,48 @@
1+
CREATE EXTENSION pg_logicalinspect;
2+
3+
-- ===================================================================
4+
-- Tests for input validation
5+
-- ===================================================================
6+
7+
SELECT pg_get_logical_snapshot_info('0-40796E18.foo');
8+
SELECT pg_get_logical_snapshot_info('0--40796E18.snap');
9+
SELECT pg_get_logical_snapshot_info('-1--40796E18.snap');
10+
SELECT pg_get_logical_snapshot_info('0/40796E18.foo.snap');
11+
SELECT pg_get_logical_snapshot_info('0/40796E18.snap');
12+
SELECT pg_get_logical_snapshot_info('');
13+
SELECT pg_get_logical_snapshot_info(NULL);
14+
SELECT pg_get_logical_snapshot_info('../snapshots');
15+
SELECT pg_get_logical_snapshot_info('../snapshots/0-40796E18.snap');
16+
17+
SELECT pg_get_logical_snapshot_meta('0-40796E18.foo');
18+
SELECT pg_get_logical_snapshot_meta('0-40796E18.foo.snap');
19+
SELECT pg_get_logical_snapshot_meta('0/40796E18.snap');
20+
SELECT pg_get_logical_snapshot_meta('');
21+
SELECT pg_get_logical_snapshot_meta(NULL);
22+
SELECT pg_get_logical_snapshot_meta('../snapshots');
23+
24+
-- ===================================================================
25+
-- Tests for permissions
26+
-- ===================================================================
27+
CREATE ROLE regress_pg_logicalinspect;
28+
29+
SELECT has_function_privilege('regress_pg_logicalinspect',
30+
'pg_get_logical_snapshot_info(text)', 'EXECUTE'); -- no
31+
SELECT has_function_privilege('regress_pg_logicalinspect',
32+
'pg_get_logical_snapshot_meta(text)', 'EXECUTE'); -- no
33+
34+
-- Functions accessible by users with role pg_read_server_files.
35+
GRANT pg_read_server_files TO regress_pg_logicalinspect;
36+
37+
SELECT has_function_privilege('regress_pg_logicalinspect',
38+
'pg_get_logical_snapshot_info(text)', 'EXECUTE'); -- yes
39+
SELECT has_function_privilege('regress_pg_logicalinspect',
40+
'pg_get_logical_snapshot_meta(text)', 'EXECUTE'); -- yes
41+
42+
-- ===================================================================
43+
-- Clean up
44+
-- ===================================================================
45+
46+
DROP ROLE regress_pg_logicalinspect;
47+
48+
DROP EXTENSION pg_logicalinspect;

‎src/backend/replication/logical/snapbuild.c

Lines changed: 7 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -1691,12 +1691,17 @@ SnapBuildSerialize(SnapBuild *builder, XLogRecPtr lsn)
16911691
* If 'missing_ok' is true, will not throw an error if the file is not found.
16921692
*/
16931693
bool
1694-
SnapBuildRestoreSnapshot(SnapBuildOnDisk *ondisk, const char *path,
1694+
SnapBuildRestoreSnapshot(SnapBuildOnDisk *ondisk, XLogRecPtr lsn,
16951695
MemoryContext context, bool missing_ok)
16961696
{
16971697
int fd;
16981698
pg_crc32c checksum;
16991699
Size sz;
1700+
char path[MAXPGPATH];
1701+
1702+
sprintf(path, "%s/%X-%X.snap",
1703+
PG_LOGICAL_SNAPSHOTS_DIR,
1704+
LSN_FORMAT_ARGS(lsn));
17001705

17011706
fd = OpenTransientFile(path, O_RDONLY | PG_BINARY);
17021707

@@ -1788,18 +1793,13 @@ static bool
17881793
SnapBuildRestore(SnapBuild *builder, XLogRecPtr lsn)
17891794
{
17901795
SnapBuildOnDisk ondisk;
1791-
char path[MAXPGPATH];
17921796

17931797
/* no point in loading a snapshot if we're already there */
17941798
if (builder->state == SNAPBUILD_CONSISTENT)
17951799
return false;
17961800

1797-
sprintf(path, "%s/%X-%X.snap",
1798-
PG_LOGICAL_SNAPSHOTS_DIR,
1799-
LSN_FORMAT_ARGS(lsn));
1800-
18011801
/* validate and restore the snapshot to 'ondisk' */
1802-
if (!SnapBuildRestoreSnapshot(&ondisk, path, builder->context, true))
1802+
if (!SnapBuildRestoreSnapshot(&ondisk, lsn, builder->context, true))
18031803
return false;
18041804

18051805
/*

‎src/include/replication/snapbuild_internal.h

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -193,7 +193,7 @@ typedef struct SnapBuildOnDisk
193193
/* variable amount of TransactionIds follows */
194194
} SnapBuildOnDisk;
195195

196-
extern bool SnapBuildRestoreSnapshot(SnapBuildOnDisk *ondisk, const char *path,
196+
extern bool SnapBuildRestoreSnapshot(SnapBuildOnDisk *ondisk, XLogRecPtr lsn,
197197
MemoryContext context, bool missing_ok);
198198

199199
#endif /* SNAPBUILD_INTERNAL_H */

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