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3a44a13232
SIG (24) and NXT (30) are obsolete DNSSEC record types, superseded by
RRSIG and NSEC in RFC 3755. Allowing them through dynamic update
exposes two distinct bugs that the surrounding GL#5818 work already
fixes as defense-in-depth:
- dns__db_findrdataset() used to REQUIRE that (covers == 0 ||
type == RRSIG), which aborts named when a SIG update reaches the
prescan foreach_rr() call. Fixed to accept dns_rdatatype_issig().
- diff.c rdata_covers() used to test only RRSIG, dropping the
covered-type field for SIG rdatas; the zone DB then filed every
SIG rdataset under typepair (SIG, 0) instead of
(SIG, covered_type) and follow-up adds collided at that bucket.
Fixed to use dns_rdatatype_issig().
Both underlying bugs are still reachable via inbound zone transfer
(diff.c rdata_covers() runs from both dns_diff_apply on the IXFR path
and dns_diff_load on the AXFR path), so the type-helper fixes above
remain necessary. For the dynamic-update path, the simplest and
safest posture is to refuse SIG and NXT outright at the front door in
ns/update.c, alongside the existing NSEC/NSEC3/non-apex-RRSIG
refusals. KEY remains permitted because it is still used to carry
public keys for SIG(0) transaction authentication.
The existing tcp-self SIG regression test is repointed to assert
REFUSED on the SIG add, a symmetric NXT test is added, and the
SIG-via-dyn-update covers-bucket test is removed because it is no
longer reachable through this entry point; AXFR-based coverage of
diff.c rdata_covers() follows in a separate commit.
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| isccfg | ||
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