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[9.20] fix: usr: Recently expired records could be returned with timestamp in future

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Under rare circumstances, the RRSet that expired at the time of
the query could be returned with TTL far in the future.  This
has been fixed.

As a side-effect, the expiration time of expired RRSets are no
longer printed out in the cache dump.

Closes #5094

Backport of MR !10048

Merge branch 'backport-5094-fix-timestamp-in-ttl-9.20' into 'bind-9.20'

See merge request isc-projects/bind9!10059
This commit is contained in:
Ondřej Surý
2025-02-03 15:05:48 +00:00
parent 619f163e68 302aca809d
commit 9a4df4caac
6 changed files with 34 additions and 50 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
bin/tests/system/serve-stale/tests.sh
View File

@@ -1649,7 +1649,7 @@ if [ $ret != 0 ]; then echo_i "failed"; fi
status=$((status + ret))
# Check that expired records are not dumped.
ret=0
grep "; expired since .* (awaiting cleanup)" ns5/named_dump.db.test$n && ret=1
grep "; expired (awaiting cleanup)" ns5/named_dump.db.test$n && ret=1
if [ $ret != 0 ]; then echo_i "failed"; fi
status=$((status + ret))
@@ -1665,13 +1665,13 @@ status=$((status + ret))
echo_i "check rndc dump expired data.example ($n)"
ret=0
awk '/; expired/ { x=$0; getline; print x, $0}' ns5/named_dump.db.test$n \
| grep "; expired since .* (awaiting cleanup) data\.example\..*A text record with a 2 second ttl" >/dev/null 2>&1 || ret=1
| grep "; expired (awaiting cleanup) data\.example\..*A text record with a 2 second ttl" >/dev/null 2>&1 || ret=1
awk '/; expired/ { x=$0; getline; print x, $0}' ns5/named_dump.db.test$n \
| grep "; expired since .* (awaiting cleanup) nodata\.example\." >/dev/null 2>&1 || ret=1
| grep "; expired (awaiting cleanup) nodata\.example\." >/dev/null 2>&1 || ret=1
awk '/; expired/ { x=$0; getline; print x, $0}' ns5/named_dump.db.test$n \
| grep "; expired since .* (awaiting cleanup) nxdomain\.example\." >/dev/null 2>&1 || ret=1
| grep "; expired (awaiting cleanup) nxdomain\.example\." >/dev/null 2>&1 || ret=1
awk '/; expired/ { x=$0; getline; print x, $0}' ns5/named_dump.db.test$n \
| grep "; expired since .* (awaiting cleanup) othertype\.example\." >/dev/null 2>&1 || ret=1
| grep "; expired (awaiting cleanup) othertype\.example\." >/dev/null 2>&1 || ret=1
# Also make sure the not expired data does not have an expired comment.
awk '/; authanswer/ { x=$0; getline; print x, $0}' ns5/named_dump.db.test$n \
| grep "; authanswer longttl\.example.*A text record with a 600 second ttl" >/dev/null 2>&1 || ret=1

10
lib/dns/masterdump.c
View File

@@ -1164,15 +1164,7 @@ again:
if (STALE(rds)) {
fprintf(f, "; stale\n");
} else if (ANCIENT(rds)) {
isc_buffer_t b;
char buf[sizeof("YYYYMMDDHHMMSS")];
memset(buf, 0, sizeof(buf));
isc_buffer_init(&b, buf, sizeof(buf) - 1);
dns_time64_totext((uint64_t)rds->ttl, &b);
fprintf(f,
"; expired since %s "
"(awaiting cleanup)\n",
buf);
fprintf(f, "; expired (awaiting cleanup)\n");
}
result = dump_rdataset(mctx, name, rds, ctx, buffer, f);
if (result != ISC_R_SUCCESS) {

30
lib/dns/qpcache.c
View File

@@ -954,15 +954,20 @@ setttl(dns_slabheader_t *header, dns_ttl_t newttl) {
}
}
static void
mark_ancient(dns_slabheader_t *header) {
setttl(header, 0);
mark(header, DNS_SLABHEADERATTR_ANCIENT);
HEADERNODE(header)->dirty = 1;
}
/*
* Caller must hold the node (write) lock.
*/
static void
expireheader(dns_slabheader_t *header, isc_rwlocktype_t *nlocktypep,
isc_rwlocktype_t *tlocktypep, dns_expire_t reason DNS__DB_FLARG) {
setttl(header, 0);
mark(header, DNS_SLABHEADERATTR_ANCIENT);
HEADERNODE(header)->dirty = 1;
mark_ancient(header);
if (isc_refcount_current(&HEADERNODE(header)->erefs) == 0) {
qpcache_t *qpdb = (qpcache_t *)header->db;
@@ -1058,7 +1063,7 @@ bindrdataset(qpcache_t *qpdb, qpcnode_t *node, dns_slabheader_t *header,
* (these records should not be cached anyway).
*/
if (KEEPSTALE(qpdb) && stale_ttl > now) {
if (!ZEROTTL(header) && KEEPSTALE(qpdb) && stale_ttl > now) {
stale = true;
} else {
/*
@@ -1073,6 +1078,7 @@ bindrdataset(qpcache_t *qpdb, qpcnode_t *node, dns_slabheader_t *header,
rdataset->rdclass = qpdb->common.rdclass;
rdataset->type = DNS_TYPEPAIR_TYPE(header->type);
rdataset->covers = DNS_TYPEPAIR_COVERS(header->type);
rdataset->ttl = !ZEROTTL(header) ? header->ttl - now : 0;
rdataset->ttl = header->ttl - now;
rdataset->trust = header->trust;
rdataset->resign = 0;
@@ -1103,7 +1109,7 @@ bindrdataset(qpcache_t *qpdb, qpcnode_t *node, dns_slabheader_t *header,
rdataset->attributes |= DNS_RDATASETATTR_STALE;
} else if (!ACTIVE(header, now)) {
rdataset->attributes |= DNS_RDATASETATTR_ANCIENT;
rdataset->ttl = header->ttl;
rdataset->ttl = 0;
}
rdataset->count = atomic_fetch_add_relaxed(&header->count, 1);
@@ -1270,8 +1276,7 @@ check_stale_header(qpcnode_t *node, dns_slabheader_t *header,
}
dns_slabheader_destroy(&header);
} else {
mark(header, DNS_SLABHEADERATTR_ANCIENT);
HEADERNODE(header)->dirty = 1;
mark_ancient(header);
*header_prev = header;
}
} else {
@@ -2233,8 +2238,7 @@ findrdataset(dns_db_t *db, dns_dbnode_t *node, dns_dbversion_t *version,
* non-zero. This is so because 'node' is an
* argument to the function.
*/
mark(header, DNS_SLABHEADERATTR_ANCIENT);
HEADERNODE(header)->dirty = 1;
mark_ancient(header);
}
} else if (EXISTS(header) && !ANCIENT(header)) {
if (header->type == matchtype) {
@@ -2585,13 +2589,6 @@ qpdb_destroy(dns_db_t *arg) {
qpcache_detach(&qpdb);
}
static void
mark_ancient(dns_slabheader_t *header) {
setttl(header, 0);
mark(header, DNS_SLABHEADERATTR_ANCIENT);
HEADERNODE(header)->dirty = 1;
}
/*%
* Clean up dead nodes. These are nodes which have no references, and
* have no data. They are dead but we could not or chose not to delete
@@ -3162,7 +3159,6 @@ find_header:
newheader->next = topheader->next;
newheader->down = topheader;
topheader->next = newheader;
qpnode->dirty = 1;
mark_ancient(header);
if (sigheader != NULL) {
mark_ancient(sigheader);

12
lib/dns/rbt-cachedb.c
View File

@@ -417,9 +417,7 @@ check_stale_header(dns_rbtnode_t *node, dns_slabheader_t *header,
}
dns_slabheader_destroy(&header);
} else {
dns__rbtdb_mark(header,
DNS_SLABHEADERATTR_ANCIENT);
RBTDB_HEADERNODE(header)->dirty = 1;
dns__rbtdb_mark_ancient(header);
*header_prev = header;
}
} else {
@@ -1401,9 +1399,7 @@ cache_findrdataset(dns_db_t *db, dns_dbnode_t *node, dns_dbversion_t *version,
* non-zero. This is so because 'node' is an
* argument to the function.
*/
dns__rbtdb_mark(header,
DNS_SLABHEADERATTR_ANCIENT);
RBTDB_HEADERNODE(header)->dirty = 1;
dns__rbtdb_mark_ancient(header);
}
} else if (EXISTS(header) && !ANCIENT(header)) {
if (header->type == matchtype) {
@@ -1589,9 +1585,7 @@ void
dns__cacherbt_expireheader(dns_slabheader_t *header,
isc_rwlocktype_t *tlocktypep,
dns_expire_t reason DNS__DB_FLARG) {
dns__rbtdb_setttl(header, 0);
dns__rbtdb_mark(header, DNS_SLABHEADERATTR_ANCIENT);
RBTDB_HEADERNODE(header)->dirty = 1;
dns__rbtdb_mark_ancient(header);
if (isc_refcount_current(&RBTDB_HEADERNODE(header)->references) == 0) {
isc_rwlocktype_t nlocktype = isc_rwlocktype_write;

20
lib/dns/rbtdb.c
View File

@@ -857,8 +857,8 @@ dns__rbtdb_mark(dns_slabheader_t *header, uint_least16_t flag) {
}
}
static void
mark_ancient(dns_slabheader_t *header) {
void
dns__rbtdb_mark_ancient(dns_slabheader_t *header) {
dns__rbtdb_setttl(header, 0);
dns__rbtdb_mark(header, DNS_SLABHEADERATTR_ANCIENT);
RBTDB_HEADERNODE(header)->dirty = 1;
@@ -2150,7 +2150,7 @@ dns__rbtdb_bindrdataset(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node,
* (these records should not be cached anyway).
*/
if (KEEPSTALE(rbtdb) && stale_ttl > now) {
if (!ZEROTTL(header) && KEEPSTALE(rbtdb) && stale_ttl > now) {
stale = true;
} else {
/*
@@ -2165,7 +2165,7 @@ dns__rbtdb_bindrdataset(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node,
rdataset->rdclass = rbtdb->common.rdclass;
rdataset->type = DNS_TYPEPAIR_TYPE(header->type);
rdataset->covers = DNS_TYPEPAIR_COVERS(header->type);
rdataset->ttl = header->ttl - now;
rdataset->ttl = !ZEROTTL(header) ? header->ttl - now : 0;
rdataset->trust = header->trust;
if (NEGATIVE(header)) {
@@ -2194,7 +2194,7 @@ dns__rbtdb_bindrdataset(dns_rbtdb_t *rbtdb, dns_rbtnode_t *node,
rdataset->attributes |= DNS_RDATASETATTR_STALE;
} else if (IS_CACHE(rbtdb) && !ACTIVE(header, now)) {
rdataset->attributes |= DNS_RDATASETATTR_ANCIENT;
rdataset->ttl = header->ttl;
rdataset->ttl = 0;
}
rdataset->count = atomic_fetch_add_relaxed(&header->count, 1);
@@ -2604,7 +2604,7 @@ dns__rbtdb_add(dns_rbtdb_t *rbtdb, dns_rbtnode_t *rbtnode,
topheader != NULL;
topheader = topheader->next)
{
mark_ancient(topheader);
dns__rbtdb_mark_ancient(topheader);
}
goto find_header;
}
@@ -2667,7 +2667,7 @@ dns__rbtdb_add(dns_rbtdb_t *rbtdb, dns_rbtnode_t *rbtnode,
* The new rdataset is better. Expire the
* ncache entry.
*/
mark_ancient(topheader);
dns__rbtdb_mark_ancient(topheader);
topheader = NULL;
goto find_header;
}
@@ -3013,9 +3013,9 @@ find_header:
changed->dirty = true;
}
if (rbtversion == NULL) {
mark_ancient(header);
dns__rbtdb_mark_ancient(header);
if (sigheader != NULL) {
mark_ancient(sigheader);
dns__rbtdb_mark_ancient(sigheader);
}
}
if (rbtversion != NULL && !header_nx) {
@@ -3119,7 +3119,7 @@ find_header:
expireheader = newheader;
}
mark_ancient(expireheader);
dns__rbtdb_mark_ancient(expireheader);
/*
* FIXME: In theory, we should mark the RRSIG
* and the header at the same time, but there is

2
lib/dns/rbtdb_p.h
View File

@@ -486,6 +486,8 @@ dns__zonerbt_addwildcards(dns_rbtdb_t *rbtdb, const dns_name_t *name,
* Cache-specific functions that are called from rbtdb.c
*/
void
dns__rbtdb_mark_ancient(dns_slabheader_t *header);
void
dns__cacherbt_expireheader(dns_slabheader_t *header,
isc_rwlocktype_t *tlocktypep,
dns_expire_t reason DNS__DB_FLARG);