Merging debian version 5.6.0-1+deb12u1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

17 files changed, 931 insertions, 1 deletions

diff --git a/debian/changelog b/debian/changelog
index 662631f..530d09e 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,11 @@
+knot-resolver (5.6.0-1+deb12u1) bookworm-security; urgency=medium
+
+  * Backport upstream fixes for CVE-2023-50868 "NSEC3"
+  * Backport upstream fixes for CVE-2023-50387 "KeyTrap"
+  * Backport upstream fix for CVE-2023-46317
+
+ -- Jakub Ružička <jakub.ruzicka@nic.cz>  Fri, 23 Feb 2024 13:16:49 +0100
+
 knot-resolver (5.6.0-1progress7u1) graograman; urgency=medium
 
   * Initial reupload to graograman.
diff --git a/debian/gbp.conf b/debian/gbp.conf
index ff17343..5b24517 100644
--- a/debian/gbp.conf
+++ b/debian/gbp.conf
@@ -1,5 +1,5 @@
 [DEFAULT]
-debian-branch = debian/master
+debian-branch = debian/bookworm
 debian-tag = debian/%(version)s
 upstream-branch = upstream
 upstream-tag = upstream/%(version)s
diff --git a/debian/patches/0001-validator-lower-the-NSEC3-iteration-limit-150-50.patch b/debian/patches/0001-validator-lower-the-NSEC3-iteration-limit-150-50.patch
new file mode 100644
index 0000000..90137eb
--- /dev/null
+++ b/debian/patches/0001-validator-lower-the-NSEC3-iteration-limit-150-50.patch
@@ -0,0 +1,32 @@
+From: =?utf-8?b?VmxhZGltw61yIMSMdW7DoXQ=?= <vladimir.cunat@nic.cz>
+Date: Tue, 2 Jan 2024 10:05:28 +0100
+Subject: validator: lower the NSEC3 iteration limit (150 -> 50)
+
+Also done by BIND9 >= 9.19.19:
+https://gitlab.isc.org/isc-projects/bind9/-/merge_requests/8515
+
+The latest real-life measurements show that values above 50 are rare:
+https://chat.dns-oarc.net/community/pl/aadp9wwrp7g7ux1b8chbzebmze
+---
+ lib/dnssec/nsec3.h | 7 ++-----
+ 1 file changed, 2 insertions(+), 5 deletions(-)
+
+diff --git a/lib/dnssec/nsec3.h b/lib/dnssec/nsec3.h
+index eb0bd39..723dc4a 100644
+--- a/lib/dnssec/nsec3.h
++++ b/lib/dnssec/nsec3.h
+@@ -11,12 +11,9 @@
+  * ...so we avoid doing all the work.  The value is a current compromise;
+  * zones shooting over get downgraded to insecure status.
+  *
+- * Original restriction wasn't that strict:
+-   https://datatracker.ietf.org/doc/html/rfc5155#section-10.3
+- * but there is discussion about officially lowering the limits:
+-   https://tools.ietf.org/id/draft-hardaker-dnsop-nsec3-guidance-02.html#section-2.3
++   https://datatracker.ietf.org/doc/html/rfc9276#name-recommendation-for-validati
+  */
+-#define KR_NSEC3_MAX_ITERATIONS 150
++#define KR_NSEC3_MAX_ITERATIONS 50
+ 
+ /**
+  * Name error response check (RFC5155 7.2.2).
diff --git a/debian/patches/0002-validator-similarly-also-limit-excessive-NSEC3-salt-.patch b/debian/patches/0002-validator-similarly-also-limit-excessive-NSEC3-salt-.patch
new file mode 100644
index 0000000..2225c90
--- /dev/null
+++ b/debian/patches/0002-validator-similarly-also-limit-excessive-NSEC3-salt-.patch
@@ -0,0 +1,143 @@
+From: =?utf-8?b?VmxhZGltw61yIMSMdW7DoXQ=?= <vladimir.cunat@nic.cz>
+Date: Tue, 2 Jan 2024 11:18:31 +0100
+Subject: validator: similarly also limit excessive NSEC3 salt length
+
+Limit combination of iterations and salt length, based on estimated
+expense of the computation.  Note that the result only differs for
+salt length > 44 which is rather nonsensical and very rare:
+https://chat.dns-oarc.net/community/pl/h58qx9sjkbgt9dajb7x988p78a
+---
+ lib/cache/api.c      |  2 +-
+ lib/cache/nsec3.c    |  2 +-
+ lib/dnssec/nsec3.c   |  4 ++--
+ lib/dnssec/nsec3.h   | 32 ++++++++++++++++++++++++++++----
+ lib/layer/validate.c |  7 ++++---
+ 5 files changed, 36 insertions(+), 11 deletions(-)
+
+diff --git a/lib/cache/api.c b/lib/cache/api.c
+index 116d775..bb627ea 100644
+--- a/lib/cache/api.c
++++ b/lib/cache/api.c
+@@ -500,7 +500,7 @@ static ssize_t stash_rrset(struct kr_cache *cache, const struct kr_query *qry,
+ 		return kr_ok();
+ 	}
+ 	if (rr->type == KNOT_RRTYPE_NSEC3 && rr->rrs.count
+-	    && knot_nsec3_iters(rr->rrs.rdata) > KR_NSEC3_MAX_ITERATIONS) {
++	    && kr_nsec3_limited_rdata(rr->rrs.rdata)) {
+ 		/* This shouldn't happen often, thanks to downgrades during validation. */
+ 		VERBOSE_MSG(qry, "=> skipping NSEC3 with too many iterations\n");
+ 		return kr_ok();
+diff --git a/lib/cache/nsec3.c b/lib/cache/nsec3.c
+index 0b70775..9832630 100644
+--- a/lib/cache/nsec3.c
++++ b/lib/cache/nsec3.c
+@@ -84,7 +84,7 @@ static knot_db_val_t key_NSEC3_name(struct key *k, const knot_dname_t *name,
+ 		.data = (uint8_t *)/*const-cast*/name,
+ 	};
+ 
+-	if (kr_fails_assert(nsec_p->libknot.iterations <= KR_NSEC3_MAX_ITERATIONS)) {
++	if (kr_fails_assert(!kr_nsec3_limited_params(&nsec_p->libknot))) {
+ 		/* This is mainly defensive; it shouldn't happen thanks to downgrades. */
+ 		return VAL_EMPTY;
+ 	}
+diff --git a/lib/dnssec/nsec3.c b/lib/dnssec/nsec3.c
+index 037d5bd..e4d314b 100644
+--- a/lib/dnssec/nsec3.c
++++ b/lib/dnssec/nsec3.c
+@@ -71,7 +71,7 @@ static int hash_name(dnssec_binary_t *hash, const dnssec_nsec3_params_t *params,
+ 		return kr_error(EINVAL);
+ 	if (!name)
+ 		return kr_error(EINVAL);
+-	if (kr_fails_assert(params->iterations <= KR_NSEC3_MAX_ITERATIONS)) {
++	if (kr_fails_assert(!kr_nsec3_limited_params(params))) {
+ 		/* This if is mainly defensive; it shouldn't happen. */
+ 		return kr_error(EINVAL);
+ 	}
+@@ -565,7 +565,7 @@ int kr_nsec3_wildcard_answer_response_check(const knot_pkt_t *pkt, knot_section_
+ 		const knot_rrset_t *rrset = knot_pkt_rr(sec, i);
+ 		if (rrset->type != KNOT_RRTYPE_NSEC3)
+ 			continue;
+-		if (knot_nsec3_iters(rrset->rrs.rdata) > KR_NSEC3_MAX_ITERATIONS) {
++		if (kr_nsec3_limited_rdata(rrset->rrs.rdata)) {
+ 			/* Avoid hashing with too many iterations.
+ 			 * If we get here, the `sname` wildcard probably ends up bogus,
+ 			 * but it gets downgraded to KR_RANK_INSECURE when validator
+diff --git a/lib/dnssec/nsec3.h b/lib/dnssec/nsec3.h
+index 723dc4a..76ef2e9 100644
+--- a/lib/dnssec/nsec3.h
++++ b/lib/dnssec/nsec3.h
+@@ -5,15 +5,39 @@
+ #pragma once
+ 
+ #include <libknot/packet/pkt.h>
++#include <libknot/rrtype/nsec3.h>
++#include <libdnssec/nsec.h>
++
++
++static inline unsigned int kr_nsec3_price(unsigned int iterations, unsigned int salt_len)
++{
++	// SHA1 works on 64-byte chunks.
++	// On iterating we hash the salt + 20 bytes of the previous hash.
++	int chunks_per_iter = (20 + salt_len - 1) / 64 + 1;
++	return (iterations + 1) * chunks_per_iter;
++}
+ 
+ /** High numbers in NSEC3 iterations don't really help security
+  *
+- * ...so we avoid doing all the work.  The value is a current compromise;
+- * zones shooting over get downgraded to insecure status.
++ * ...so we avoid doing all the work.  The limit is a current compromise;
++ * answers using NSEC3 over kr_nsec3_limited* get downgraded to insecure status.
+  *
+    https://datatracker.ietf.org/doc/html/rfc9276#name-recommendation-for-validati
+  */
+-#define KR_NSEC3_MAX_ITERATIONS 50
++static inline bool kr_nsec3_limited(unsigned int iterations, unsigned int salt_len)
++{
++	const int MAX_ITERATIONS = 50; // limit with short salt length
++	return kr_nsec3_price(iterations, salt_len) > MAX_ITERATIONS + 1;
++}
++static inline bool kr_nsec3_limited_rdata(const knot_rdata_t *rd)
++{
++	return kr_nsec3_limited(knot_nsec3_iters(rd), knot_nsec3_salt_len(rd));
++}
++static inline bool kr_nsec3_limited_params(const dnssec_nsec3_params_t *params)
++{
++	return kr_nsec3_limited(params->iterations, params->salt.size);
++}
++
+ 
+ /**
+  * Name error response check (RFC5155 7.2.2).
+@@ -36,7 +60,7 @@ int kr_nsec3_name_error_response_check(const knot_pkt_t *pkt, knot_section_t sec
+  *                     KNOT_ERANGE - NSEC3 RR that covers a wildcard
+  *                     has been found, but has opt-out flag set;
+  *                     otherwise - error.
+- * Records over KR_NSEC3_MAX_ITERATIONS are skipped, so you probably get kr_error(ENOENT).
++ * Too expensive NSEC3 records are skipped, so you probably get kr_error(ENOENT).
+  */
+ int kr_nsec3_wildcard_answer_response_check(const knot_pkt_t *pkt, knot_section_t section_id,
+                                             const knot_dname_t *sname, int trim_to_next);
+diff --git a/lib/layer/validate.c b/lib/layer/validate.c
+index 93f1d4f..5fea99d 100644
+--- a/lib/layer/validate.c
++++ b/lib/layer/validate.c
+@@ -128,14 +128,15 @@ static bool maybe_downgrade_nsec3(const ranked_rr_array_entry_t *e, struct kr_qu
+ 	const knot_rdataset_t *rrs = &e->rr->rrs;
+ 	knot_rdata_t *rd = rrs->rdata;
+ 	for (int j = 0; j < rrs->count; ++j, rd = knot_rdataset_next(rd)) {
+-		if (knot_nsec3_iters(rd) > KR_NSEC3_MAX_ITERATIONS)
++		if (kr_nsec3_limited_rdata(rd))
+ 			goto do_downgrade;
+ 	}
+ 	return false;
+ 
+ do_downgrade: // we do this deep inside calls because of having signer name available
+-	VERBOSE_MSG(qry, "<= DNSSEC downgraded due to NSEC3 iterations %d > %d\n",
+-			(int)knot_nsec3_iters(rd), (int)KR_NSEC3_MAX_ITERATIONS);
++	VERBOSE_MSG(qry,
++		"<= DNSSEC downgraded due to expensive NSEC3: %d iterations, %d salt length\n",
++		(int)knot_nsec3_iters(rd), (int)knot_nsec3_salt_len(rd));
+ 	qry->flags.DNSSEC_WANT = false;
+ 	qry->flags.DNSSEC_INSECURE = true;
+ 	rank_records(qry, true, KR_RANK_INSECURE, vctx->zone_name);
diff --git a/debian/patches/0003-lib-cache-limit-the-amount-of-work-on-SHA1.patch b/debian/patches/0003-lib-cache-limit-the-amount-of-work-on-SHA1.patch
new file mode 100644
index 0000000..2768b78
--- /dev/null
+++ b/debian/patches/0003-lib-cache-limit-the-amount-of-work-on-SHA1.patch
@@ -0,0 +1,60 @@
+From: =?utf-8?b?VmxhZGltw61yIMSMdW7DoXQ=?= <vladimir.cunat@nic.cz>
+Date: Sun, 11 Feb 2024 10:00:32 +0100
+Subject: lib/cache: limit the amount of work on SHA1
+
+That's when searching NSEC3 aggressive cache.
+---
+ lib/cache/nsec3.c  | 14 ++++++++++++++
+ lib/dnssec/nsec3.h | 12 ++++++++++++
+ 2 files changed, 26 insertions(+)
+
+diff --git a/lib/cache/nsec3.c b/lib/cache/nsec3.c
+index 9832630..2716456 100644
+--- a/lib/cache/nsec3.c
++++ b/lib/cache/nsec3.c
+@@ -272,8 +272,22 @@ int nsec3_encloser(struct key *k, struct answer *ans,
+ 	const int zname_labels = knot_dname_labels(k->zname, NULL);
+ 	int last_nxproven_labels = -1;
+ 	const knot_dname_t *name = qry->sname;
++
++	/* Avoid doing too much work on SHA1; we might consider that a part of mitigating
++	 *    CVE-2023-50868: NSEC3 closest encloser proof can exhaust CPU
++	 * As currently the code iterates from the longest name, we limit that.
++	 * Note that we don't want to limit too much, as the alternative usually includes
++	 * sending more queries upstream, which would come with nontrivial work, too.
++	 */
++	const int max_labels = zname_labels + kr_nsec3_max_depth(&ans->nsec_p.libknot);
++	if (sname_labels > max_labels)
++		VERBOSE_MSG(qry, "=> NSEC3 hashing partly skipped due to too long SNAME (CVE-2023-50868)\n");
++
+ 	for (int name_labels = sname_labels; name_labels >= zname_labels;
+ 					--name_labels, name += 1 + name[0]) {
++		if (name_labels > max_labels)
++			continue; // avoid the hashing
++
+ 		/* Find a previous-or-equal NSEC3 in cache covering the name,
+ 		 * checking TTL etc. */
+ 		const knot_db_val_t key = key_NSEC3_name(k, name, false, &ans->nsec_p);
+diff --git a/lib/dnssec/nsec3.h b/lib/dnssec/nsec3.h
+index 76ef2e9..a28d3c7 100644
+--- a/lib/dnssec/nsec3.h
++++ b/lib/dnssec/nsec3.h
+@@ -38,6 +38,18 @@ static inline bool kr_nsec3_limited_params(const dnssec_nsec3_params_t *params)
+ 	return kr_nsec3_limited(params->iterations, params->salt.size);
+ }
+ 
++/** Return limit on NSEC3 depth.  The point is to avoid doing too much work on SHA1.
++ *
++ * CVE-2023-50868: NSEC3 closest encloser proof can exhaust CPU
++ *
++ * 128 is chosen so that zones with good NSEC3 parameters (giving _price() == 1)
++ * won't be limited in any way.  Performance doesn't seem too bad with that either.
++ */
++static inline int kr_nsec3_max_depth(const dnssec_nsec3_params_t *params)
++{
++	return 128 / kr_nsec3_price(params->iterations, params->salt.size);
++}
++
+ 
+ /**
+  * Name error response check (RFC5155 7.2.2).
diff --git a/debian/patches/0004-validator-limit-the-amount-of-work-on-SHA1-in-NSEC3-.patch b/debian/patches/0004-validator-limit-the-amount-of-work-on-SHA1-in-NSEC3-.patch
new file mode 100644
index 0000000..a72b7e5
--- /dev/null
+++ b/debian/patches/0004-validator-limit-the-amount-of-work-on-SHA1-in-NSEC3-.patch
@@ -0,0 +1,31 @@
+From: =?utf-8?b?VmxhZGltw61yIMSMdW7DoXQ=?= <vladimir.cunat@nic.cz>
+Date: Mon, 12 Feb 2024 11:16:37 +0100
+Subject: validator: limit the amount of work on SHA1 in NSEC3 proofs
+
+---
+ lib/dnssec/nsec3.c | 12 ++++++++++++
+ 1 file changed, 12 insertions(+)
+
+diff --git a/lib/dnssec/nsec3.c b/lib/dnssec/nsec3.c
+index e4d314b..4199f25 100644
+--- a/lib/dnssec/nsec3.c
++++ b/lib/dnssec/nsec3.c
+@@ -146,6 +146,18 @@ static int closest_encloser_match(int *flags, const knot_rrset_t *nsec3,
+ 	const knot_dname_t *encloser = knot_wire_next_label(name, NULL);
+ 	*skipped = 1;
+ 
++	/* Avoid doing too much work on SHA1, mitigating:
++	 *   CVE-2023-50868: NSEC3 closest encloser proof can exhaust CPU
++	 * We log nothing here; it wouldn't be easy from this place
++	 * and huge SNAME should be suspicious on its own.
++	 */
++	const int max_labels = knot_dname_labels(nsec3->owner, NULL) - 1
++				+ kr_nsec3_max_depth(&params);
++	for (int l = knot_dname_labels(encloser, NULL); l > max_labels; --l) {
++		encloser = knot_wire_next_label(encloser, NULL);
++		++(*skipped);
++	}
++
+ 	while(encloser) {
+ 		ret = hash_name(&name_hash, &params, encloser);
+ 		if (ret != 0)
diff --git a/debian/patches/0005-validator-refuse-to-validate-answers-with-more-than-.patch b/debian/patches/0005-validator-refuse-to-validate-answers-with-more-than-.patch
new file mode 100644
index 0000000..dd547a1
--- /dev/null
+++ b/debian/patches/0005-validator-refuse-to-validate-answers-with-more-than-.patch
@@ -0,0 +1,37 @@
+From: =?utf-8?b?VmxhZGltw61yIMSMdW7DoXQ=?= <vladimir.cunat@nic.cz>
+Date: Mon, 12 Feb 2024 11:16:47 +0100
+Subject: validator: refuse to validate answers with more than 8 NSEC3 records
+
+---
+ lib/layer/validate.c | 18 ++++++++++++++++++
+ 1 file changed, 18 insertions(+)
+
+diff --git a/lib/layer/validate.c b/lib/layer/validate.c
+index 5fea99d..95a7624 100644
+--- a/lib/layer/validate.c
++++ b/lib/layer/validate.c
+@@ -1120,6 +1120,24 @@ static int validate(kr_layer_t *ctx, knot_pkt_t *pkt)
+ 		}
+ 	}
+ 
++	/* Check for too many NSEC3 records.  That's an issue, as some parts of validation
++	 * are quadratic in their count, doing nontrivial computations inside.
++	 * Also there seems to be no use in sending many NSEC3 records. */
++	if (!qry->flags.CACHED) {
++		const knot_pktsection_t *sec = knot_pkt_section(pkt, KNOT_AUTHORITY);
++		int count = 0;
++		for (int i = 0; i < sec->count; ++i)
++			count += (knot_pkt_rr(sec, i)->type == KNOT_RRTYPE_NSEC3);
++		if (count > 8) {
++			VERBOSE_MSG(qry, "<= too many NSEC3 records in AUTHORITY (%d)\n", count);
++			kr_request_set_extended_error(req, KNOT_EDNS_EDE_NSEC3_ITERS,
++				/* It's not about iteration values per se, but close enough. */
++				"DYRH: too many NSEC3 records");
++			qry->flags.DNSSEC_BOGUS = true;
++			return KR_STATE_FAIL;
++		}
++	}
++
+ 	if (knot_wire_get_aa(pkt->wire) && qtype == KNOT_RRTYPE_DNSKEY) {
+ 		const knot_rrset_t *ds = qry->zone_cut.trust_anchor;
+ 		if (ds && !kr_ds_algo_support(ds)) {
diff --git a/debian/patches/0006-validator-compatibility-with-older-libknot-versions.patch b/debian/patches/0006-validator-compatibility-with-older-libknot-versions.patch
new file mode 100644
index 0000000..0bb8fb1
--- /dev/null
+++ b/debian/patches/0006-validator-compatibility-with-older-libknot-versions.patch
@@ -0,0 +1,22 @@
+From: =?utf-8?b?VmxhZGltw61yIMSMdW7DoXQ=?= <vladimir.cunat@nic.cz>
+Date: Mon, 12 Feb 2024 11:30:50 +0100
+Subject: validator: compatibility with older libknot versions
+
+The value is in IANA registry, so it's very constant anyway.
+---
+ lib/layer/validate.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/lib/layer/validate.c b/lib/layer/validate.c
+index 95a7624..6c0d7ad 100644
+--- a/lib/layer/validate.c
++++ b/lib/layer/validate.c
+@@ -1130,7 +1130,7 @@ static int validate(kr_layer_t *ctx, knot_pkt_t *pkt)
+ 			count += (knot_pkt_rr(sec, i)->type == KNOT_RRTYPE_NSEC3);
+ 		if (count > 8) {
+ 			VERBOSE_MSG(qry, "<= too many NSEC3 records in AUTHORITY (%d)\n", count);
+-			kr_request_set_extended_error(req, KNOT_EDNS_EDE_NSEC3_ITERS,
++			kr_request_set_extended_error(req, 27/*KNOT_EDNS_EDE_NSEC3_ITERS*/,
+ 				/* It's not about iteration values per se, but close enough. */
+ 				"DYRH: too many NSEC3 records");
+ 			qry->flags.DNSSEC_BOGUS = true;
diff --git a/debian/patches/0007-lib-cache-bump-CACHE_VERSION.patch b/debian/patches/0007-lib-cache-bump-CACHE_VERSION.patch
new file mode 100644
index 0000000..36c8aa4
--- /dev/null
+++ b/debian/patches/0007-lib-cache-bump-CACHE_VERSION.patch
@@ -0,0 +1,25 @@
+From: =?utf-8?b?VmxhZGltw61yIMSMdW7DoXQ=?= <vladimir.cunat@nic.cz>
+Date: Fri, 23 Feb 2024 10:07:35 +0100
+Subject: lib/cache: bump CACHE_VERSION
+
+Ideally we would've done that at once with increasing NSEC3 strictness,
+i.e. in 5.7.1 + 6.0.6, as otherwise we could run into some recoverable
+assertions until the records got removed or expired.
+We at least do the bump now.
+---
+ lib/cache/api.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/lib/cache/api.c b/lib/cache/api.c
+index bb627ea..f71a8d0 100644
+--- a/lib/cache/api.c
++++ b/lib/cache/api.c
+@@ -40,7 +40,7 @@
+ 
+ 
+ /** Cache version */
+-static const uint16_t CACHE_VERSION = 6;
++static const uint16_t CACHE_VERSION = 7;
+ /** Key size */
+ #define KEY_HSIZE (sizeof(uint8_t) + sizeof(uint16_t))
+ #define KEY_SIZE (KEY_HSIZE + KNOT_DNAME_MAXLEN)
diff --git a/debian/patches/0008-lib-dnssec-kr_rrset_validate_with_key-deduplicate-cl.patch b/debian/patches/0008-lib-dnssec-kr_rrset_validate_with_key-deduplicate-cl.patch
new file mode 100644
index 0000000..85fff28
--- /dev/null
+++ b/debian/patches/0008-lib-dnssec-kr_rrset_validate_with_key-deduplicate-cl.patch
@@ -0,0 +1,43 @@
+From: =?utf-8?b?VmxhZGltw61yIMSMdW7DoXQ=?= <vladimir.cunat@nic.cz>
+Date: Sat, 30 Dec 2023 09:20:56 +0100
+Subject: lib/dnssec kr_rrset_validate_with_key(): deduplicate cleanup
+
+---
+ lib/dnssec.c | 11 +++++------
+ 1 file changed, 5 insertions(+), 6 deletions(-)
+
+diff --git a/lib/dnssec.c b/lib/dnssec.c
+index d6ae3cc..c536357 100644
+--- a/lib/dnssec.c
++++ b/lib/dnssec.c
+@@ -356,9 +356,8 @@ static int kr_rrset_validate_with_key(kr_rrset_validation_ctx_t *vctx,
+ 			int retv = validate_rrsig_rr(&val_flgs, covered_labels, rdata_j,
+ 							key_alg, keytag, vctx);
+ 			if (retv == kr_error(EAGAIN)) {
+-				kr_dnssec_key_free(&created_key);
+ 				vctx->result = retv;
+-				return retv;
++				goto finish;
+ 			} else if (retv != 0) {
+ 				continue;
+ 			}
+@@ -392,15 +391,15 @@ static int kr_rrset_validate_with_key(kr_rrset_validation_ctx_t *vctx,
+ 
+ 			trim_ttl(covered, rdata_j, vctx);
+ 
+-			kr_dnssec_key_free(&created_key);
+-			vctx->result = kr_ok();
+ 			kr_rank_set(&vctx->rrs->at[i]->rank, KR_RANK_SECURE); /* upgrade from bogus */
+-			return vctx->result;
++			vctx->result = kr_ok();
++			goto finish;
+ 		}
+ 	}
+ 	/* No applicable key found, cannot be validated. */
+-	kr_dnssec_key_free(&created_key);
+ 	vctx->result = kr_error(ENOENT);
++finish:
++	kr_dnssec_key_free(&created_key);
+ 	return vctx->result;
+ }
+ 
diff --git a/debian/patches/0009-lib-resolve-kr_request_set_extended_error-tweak-prio.patch b/debian/patches/0009-lib-resolve-kr_request_set_extended_error-tweak-prio.patch
new file mode 100644
index 0000000..bca80ea
--- /dev/null
+++ b/debian/patches/0009-lib-resolve-kr_request_set_extended_error-tweak-prio.patch
@@ -0,0 +1,25 @@
+From: =?utf-8?b?VmxhZGltw61yIMSMdW7DoXQ=?= <vladimir.cunat@nic.cz>
+Date: Mon, 1 Jan 2024 16:05:46 +0100
+Subject: lib/resolve kr_request_set_extended_error(): tweak priorities
+
+Keep the first error in case priorities are equal.
+
+At least with the current KeyTrap topic that should work better,
+but blaming a single error is alchemy anyway, at least in some cases.
+---
+ lib/resolve.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/lib/resolve.c b/lib/resolve.c
+index aa3d521..9e82e6f 100644
+--- a/lib/resolve.c
++++ b/lib/resolve.c
+@@ -1684,7 +1684,7 @@ int kr_request_set_extended_error(struct kr_request *request, int info_code, con
+ 		return KNOT_EDNS_EDE_NONE;
+ 	}
+ 
+-	if (ede_priority(info_code) >= ede_priority(ede->info_code)) {
++	if (ede_priority(info_code) > ede_priority(ede->info_code)) {
+ 		ede->info_code = info_code;
+ 		ede->extra_text = extra_text;
+ 	}
diff --git a/debian/patches/0010-mitigate-KeyTrap-DoS-CVE-2023-50387.patch b/debian/patches/0010-mitigate-KeyTrap-DoS-CVE-2023-50387.patch
new file mode 100644
index 0000000..d6109e0
--- /dev/null
+++ b/debian/patches/0010-mitigate-KeyTrap-DoS-CVE-2023-50387.patch
@@ -0,0 +1,233 @@
+From: =?utf-8?b?VmxhZGltw61yIMSMdW7DoXQ=?= <vladimir.cunat@nic.cz>
+Date: Mon, 1 Jan 2024 16:21:10 +0100
+Subject: mitigate KeyTrap DoS = CVE-2023-50387
+
+---
+ daemon/engine.c            |  1 +
+ daemon/lua/kres-gen-30.lua |  3 +++
+ daemon/lua/kres-gen-31.lua |  3 +++
+ daemon/lua/kres-gen-32.lua |  3 +++
+ lib/defines.h              |  2 ++
+ lib/dnssec.c               | 28 ++++++++++++++++++++++++++++
+ lib/dnssec.h               |  1 +
+ lib/layer/validate.c       |  7 +++++++
+ lib/resolve.h              |  3 +++
+ lib/rplan.h                |  6 ++++++
+ 10 files changed, 57 insertions(+)
+
+diff --git a/daemon/engine.c b/daemon/engine.c
+index 26c225f..a3f439f 100644
+--- a/daemon/engine.c
++++ b/daemon/engine.c
+@@ -492,6 +492,7 @@ static int init_resolver(struct engine *engine)
+ 	/* Open resolution context */
+ 	ctx->trust_anchors = trie_create(NULL);
+ 	ctx->negative_anchors = trie_create(NULL);
++	ctx->vld_limit_crypto = KR_VLD_LIMIT_CRYPTO_DEFAULT;
+ 	ctx->pool = engine->pool;
+ 	ctx->modules = &engine->modules;
+ 	ctx->cache_rtt_tout_retry_interval = KR_NS_TIMEOUT_RETRY_INTERVAL;
+diff --git a/daemon/lua/kres-gen-30.lua b/daemon/lua/kres-gen-30.lua
+index 4353c5c..01ae6ac 100644
+--- a/daemon/lua/kres-gen-30.lua
++++ b/daemon/lua/kres-gen-30.lua
+@@ -336,6 +336,8 @@ struct kr_query {
+ 	struct kr_qflags forward_flags;
+ 	uint32_t secret;
+ 	uint32_t uid;
++	int32_t vld_limit_crypto_remains;
++	uint32_t vld_limit_uid;
+ 	uint64_t creation_time_mono;
+ 	uint64_t timestamp_mono;
+ 	struct timeval timestamp;
+@@ -353,6 +355,7 @@ struct kr_context {
+ 	knot_rrset_t *upstream_opt_rr;
+ 	trie_t *trust_anchors;
+ 	trie_t *negative_anchors;
++	int32_t vld_limit_crypto;
+ 	struct kr_zonecut root_hints;
+ 	struct kr_cache cache;
+ 	unsigned int cache_rtt_tout_retry_interval;
+diff --git a/daemon/lua/kres-gen-31.lua b/daemon/lua/kres-gen-31.lua
+index a68dd65..c3845ec 100644
+--- a/daemon/lua/kres-gen-31.lua
++++ b/daemon/lua/kres-gen-31.lua
+@@ -336,6 +336,8 @@ struct kr_query {
+ 	struct kr_qflags forward_flags;
+ 	uint32_t secret;
+ 	uint32_t uid;
++	int32_t vld_limit_crypto_remains;
++	uint32_t vld_limit_uid;
+ 	uint64_t creation_time_mono;
+ 	uint64_t timestamp_mono;
+ 	struct timeval timestamp;
+@@ -353,6 +355,7 @@ struct kr_context {
+ 	knot_rrset_t *upstream_opt_rr;
+ 	trie_t *trust_anchors;
+ 	trie_t *negative_anchors;
++	int32_t vld_limit_crypto;
+ 	struct kr_zonecut root_hints;
+ 	struct kr_cache cache;
+ 	unsigned int cache_rtt_tout_retry_interval;
+diff --git a/daemon/lua/kres-gen-32.lua b/daemon/lua/kres-gen-32.lua
+index 222891e..2c407d4 100644
+--- a/daemon/lua/kres-gen-32.lua
++++ b/daemon/lua/kres-gen-32.lua
+@@ -337,6 +337,8 @@ struct kr_query {
+ 	struct kr_qflags forward_flags;
+ 	uint32_t secret;
+ 	uint32_t uid;
++	int32_t vld_limit_crypto_remains;
++	uint32_t vld_limit_uid;
+ 	uint64_t creation_time_mono;
+ 	uint64_t timestamp_mono;
+ 	struct timeval timestamp;
+@@ -354,6 +356,7 @@ struct kr_context {
+ 	knot_rrset_t *upstream_opt_rr;
+ 	trie_t *trust_anchors;
+ 	trie_t *negative_anchors;
++	int32_t vld_limit_crypto;
+ 	struct kr_zonecut root_hints;
+ 	struct kr_cache cache;
+ 	unsigned int cache_rtt_tout_retry_interval;
+diff --git a/lib/defines.h b/lib/defines.h
+index 6b6dac5..e832892 100644
+--- a/lib/defines.h
++++ b/lib/defines.h
+@@ -57,6 +57,8 @@ static inline int KR_COLD kr_error(int x) {
+ #define KR_COUNT_NO_NSADDR_LIMIT 5
+ #define KR_CONSUME_FAIL_ROW_LIMIT 3 /* Maximum number of KR_STATE_FAIL in a row. */
+ 
++#define KR_VLD_LIMIT_CRYPTO_DEFAULT 32 /**< default for struct kr_query::vld_limit_crypto */
++
+ /*
+  * Defines.
+  */
+diff --git a/lib/dnssec.c b/lib/dnssec.c
+index c536357..1e6eb58 100644
+--- a/lib/dnssec.c
++++ b/lib/dnssec.c
+@@ -240,6 +240,29 @@ fail:
+ 	return NULL;
+ }
+ 
++/// Return if we want to afford yet another crypto-validation (and account it).
++static bool check_crypto_limit(const kr_rrset_validation_ctx_t *vctx)
++{
++	if (vctx->limit_crypto_remains == NULL)
++		return true; // no limiting
++	if (*vctx->limit_crypto_remains > 0) {
++		--*vctx->limit_crypto_remains;
++		return true;
++	}
++	// We got over limit.  There are optional actions to do.
++	if (vctx->log_qry && kr_log_is_debug_qry(VALIDATOR, vctx->log_qry)) {
++		auto_free char *name_str = kr_dname_text(vctx->zone_name);
++		kr_log_q(vctx->log_qry, VALIDATOR,
++			"expensive crypto limited, mitigating CVE-2023-50387, current zone: %s\n",
++			name_str);
++	}
++	if (vctx->log_qry && vctx->log_qry->request) {
++		kr_request_set_extended_error(vctx->log_qry->request, KNOT_EDNS_EDE_BOGUS,
++				"EAIE: expensive crypto limited, mitigating CVE-2023-50387");
++	}
++	return false;
++}
++
+ static int kr_svldr_rrset_with_key(knot_rrset_t *rrs, const knot_rdataset_t *rrsigs,
+ 				kr_rrset_validation_ctx_t *vctx, const kr_svldr_key_t *key)
+ {
+@@ -258,6 +281,8 @@ static int kr_svldr_rrset_with_key(knot_rrset_t *rrs, const knot_rdataset_t *rrs
+ 		} else if (retv != 0) {
+ 			continue;
+ 		}
++		if (!check_crypto_limit(vctx))
++			return vctx->result = kr_error(E2BIG);
+ 		// We only expect non-expanded wildcard records in input;
+ 		// that also means we don't need to perform non-existence proofs.
+ 		const int trim_labels = (val_flgs & FLG_WILDCARD_EXPANSION) ? 1 : 0;
+@@ -367,6 +392,9 @@ static int kr_rrset_validate_with_key(kr_rrset_validation_ctx_t *vctx,
+ 					break;
+ 				}
+ 			}
++			if (!check_crypto_limit(vctx)) {
++				goto finish;
++			}
+ 			if (kr_check_signature(rdata_j, key, covered, trim_labels) != 0) {
+ 				vctx->rrs_counters.crypto_invalid++;
+ 				continue;
+diff --git a/lib/dnssec.h b/lib/dnssec.h
+index 0fbd47c..ca737cf 100644
+--- a/lib/dnssec.h
++++ b/lib/dnssec.h
+@@ -44,6 +44,7 @@ struct kr_rrset_validation_ctx {
+ 	uint32_t flags;			/*!< Output - Flags. */
+ 	uint32_t err_cnt;		/*!< Output - Number of validation failures. */
+ 	uint32_t cname_norrsig_cnt;	/*!< Output - Number of CNAMEs missing RRSIGs. */
++	int32_t *limit_crypto_remains;  /*!< Optional pointer to struct kr_query::vld_limit_crypto_remains */
+ 
+ 	/** Validation result: kr_error() code.
+ 	 *
+diff --git a/lib/layer/validate.c b/lib/layer/validate.c
+index 6c0d7ad..4882da8 100644
+--- a/lib/layer/validate.c
++++ b/lib/layer/validate.c
+@@ -276,6 +276,7 @@ static int validate_records(struct kr_request *req, knot_pkt_t *answer, knot_mm_
+ 		.err_cnt	= 0,
+ 		.cname_norrsig_cnt = 0,
+ 		.result		= 0,
++		.limit_crypto_remains = &qry->vld_limit_crypto_remains,
+ 		.log_qry	= qry,
+ 	};
+ 
+@@ -384,6 +385,7 @@ static int validate_keyset(struct kr_request *req, knot_pkt_t *answer, bool has_
+ 			.has_nsec3	= has_nsec3,
+ 			.flags		= 0,
+ 			.result		= 0,
++			.limit_crypto_remains = &qry->vld_limit_crypto_remains,
+ 			.log_qry	= qry,
+ 		};
+ 		int ret = kr_dnskeys_trusted(&vctx, sig_rds, qry->zone_cut.trust_anchor);
+@@ -1030,6 +1032,11 @@ static int validate(kr_layer_t *ctx, knot_pkt_t *pkt)
+ 	struct kr_request *req = ctx->req;
+ 	struct kr_query *qry = req->current_query;
+ 
++	if (qry->vld_limit_uid != qry->uid) {
++		qry->vld_limit_uid = qry->uid;
++		qry->vld_limit_crypto_remains = req->ctx->vld_limit_crypto;
++	}
++
+ 	/* Ignore faulty or unprocessed responses. */
+ 	if (ctx->state & (KR_STATE_FAIL|KR_STATE_CONSUME)) {
+ 		return ctx->state;
+diff --git a/lib/resolve.h b/lib/resolve.h
+index 97ba07b..a2d5ec9 100644
+--- a/lib/resolve.h
++++ b/lib/resolve.h
+@@ -162,6 +162,9 @@ struct kr_context
+ 
+ 	trie_t *trust_anchors;
+ 	trie_t *negative_anchors;
++	/** Validator's limit on the number of cryptographic steps for a single upstream packet. */
++	int32_t vld_limit_crypto;
++
+ 	struct kr_zonecut root_hints;
+ 	struct kr_cache cache;
+ 	unsigned cache_rtt_tout_retry_interval;
+diff --git a/lib/rplan.h b/lib/rplan.h
+index 891781f..68174af 100644
+--- a/lib/rplan.h
++++ b/lib/rplan.h
+@@ -87,6 +87,12 @@ struct kr_query {
+ 	struct kr_qflags forward_flags;
+ 	uint32_t secret;
+ 	uint32_t uid; /**< Query iteration number, unique within the kr_rplan. */
++
++	/** Remaining limit; see kr_query::vld_limit_crypto docs */
++	int32_t  vld_limit_crypto_remains;
++	/** ::uid value to which this remaining limit applies. */
++	uint32_t vld_limit_uid;
++
+ 	uint64_t creation_time_mono; /* The time of query's creation (milliseconds).
+ 				 * Or time of creation of an oldest
+ 				 * ancestor if it is a subquery. */
diff --git a/debian/patches/0011-mitigate-KeyTrap-DoS-CVE-2023-50387.patch b/debian/patches/0011-mitigate-KeyTrap-DoS-CVE-2023-50387.patch
new file mode 100644
index 0000000..e074a94
--- /dev/null
+++ b/debian/patches/0011-mitigate-KeyTrap-DoS-CVE-2023-50387.patch
@@ -0,0 +1,80 @@
+From: =?utf-8?b?VmxhZGltw61yIMSMdW7DoXQ=?= <vladimir.cunat@nic.cz>
+Date: Tue, 16 Jan 2024 07:35:20 +0100
+Subject: mitigate KeyTrap DoS = CVE-2023-50387
+
+Improve: don't retry in this case.
+---
+ lib/dnssec.c         | 7 ++++---
+ lib/layer/validate.c | 4 ++++
+ lib/resolve.c        | 4 +++-
+ 3 files changed, 11 insertions(+), 4 deletions(-)
+
+diff --git a/lib/dnssec.c b/lib/dnssec.c
+index 1e6eb58..262570c 100644
+--- a/lib/dnssec.c
++++ b/lib/dnssec.c
+@@ -134,7 +134,7 @@ int kr_rrset_validate(kr_rrset_validation_ctx_t *vctx, knot_rrset_t *covered)
+ 	memset(&vctx->rrs_counters, 0, sizeof(vctx->rrs_counters));
+ 	for (unsigned i = 0; i < vctx->keys->rrs.count; ++i) {
+ 		int ret = kr_rrset_validate_with_key(vctx, covered, i, NULL);
+-		if (ret == 0) {
++		if (ret == 0 || ret == kr_error(E2BIG)) {
+ 			return ret;
+ 		}
+ 	}
+@@ -307,7 +307,7 @@ int kr_svldr_rrset(knot_rrset_t *rrs, const knot_rdataset_t *rrsigs,
+ 	}
+ 	for (ssize_t i = 0; i < ctx->keys.len; ++i) {
+ 		kr_svldr_rrset_with_key(rrs, rrsigs, &ctx->vctx, &ctx->keys.at[i]);
+-		if (ctx->vctx.result == 0)
++		if (ctx->vctx.result == 0 || ctx->vctx.result == kr_error(E2BIG))
+ 			break;
+ 	}
+ 	return ctx->vctx.result;
+@@ -393,6 +393,7 @@ static int kr_rrset_validate_with_key(kr_rrset_validation_ctx_t *vctx,
+ 				}
+ 			}
+ 			if (!check_crypto_limit(vctx)) {
++				vctx->result = kr_error(E2BIG);
+ 				goto finish;
+ 			}
+ 			if (kr_check_signature(rdata_j, key, covered, trim_labels) != 0) {
+@@ -475,7 +476,7 @@ int kr_dnskeys_trusted(kr_rrset_validation_ctx_t *vctx, const knot_rdataset_t *s
+ 		if (ret == 0)
+ 			ret = kr_svldr_rrset_with_key(keys, sigs, vctx, &key);
+ 		svldr_key_del(&key);
+-		if (ret == 0) {
++		if (ret == 0 || ret == kr_error(E2BIG)) {
+ 			kr_assert(vctx->result == 0);
+ 			return vctx->result;
+ 		}
+diff --git a/lib/layer/validate.c b/lib/layer/validate.c
+index 4882da8..1fdc57d 100644
+--- a/lib/layer/validate.c
++++ b/lib/layer/validate.c
+@@ -1177,6 +1177,10 @@ static int validate(kr_layer_t *ctx, knot_pkt_t *pkt)
+ 		ret = validate_records(req, pkt, req->rplan.pool, has_nsec3);
+ 		if (ret == KNOT_EDOWNGRADED) {
+ 			return KR_STATE_DONE;
++		} else if (ret == kr_error(E2BIG)) {
++			qry->flags.DNSSEC_BOGUS = true;
++			return KR_STATE_FAIL;
++
+ 		} else if (ret != 0) {
+ 			/* something exceptional - no DNS key, empty pointers etc
+ 			 * normally it shouldn't happen */
+diff --git a/lib/resolve.c b/lib/resolve.c
+index 9e82e6f..456065b 100644
+--- a/lib/resolve.c
++++ b/lib/resolve.c
+@@ -880,7 +880,9 @@ int kr_resolve_consume(struct kr_request *request, struct kr_transport **transpo
+ 
+ 	/* Do not finish with bogus answer. */
+ 	if (qry->flags.DNSSEC_BOGUS)  {
+-		if (qry->flags.FORWARD || qry->flags.STUB) {
++		if (qry->flags.FORWARD || qry->flags.STUB
++				/* Probably CPU exhaustion attempt, so do not retry. */
++				|| qry->vld_limit_crypto_remains <= 0) {
+ 			return KR_STATE_FAIL;
+ 		}
+ 		/* Other servers might not have broken DNSSEC. */
diff --git a/debian/patches/0012-lib-dnssec-fix-imprecise-assertion.patch b/debian/patches/0012-lib-dnssec-fix-imprecise-assertion.patch
new file mode 100644
index 0000000..8612afb
--- /dev/null
+++ b/debian/patches/0012-lib-dnssec-fix-imprecise-assertion.patch
@@ -0,0 +1,22 @@
+From: =?utf-8?b?VmxhZGltw61yIMSMdW7DoXQ=?= <vladimir.cunat@nic.cz>
+Date: Fri, 23 Feb 2024 09:33:21 +0100
+Subject: lib/dnssec: fix imprecise assertion
+
+It was no longer correct after commit cc5051b444130 (KeyTrap).
+---
+ lib/dnssec.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/lib/dnssec.c b/lib/dnssec.c
+index 262570c..fcae473 100644
+--- a/lib/dnssec.c
++++ b/lib/dnssec.c
+@@ -477,7 +477,7 @@ int kr_dnskeys_trusted(kr_rrset_validation_ctx_t *vctx, const knot_rdataset_t *s
+ 			ret = kr_svldr_rrset_with_key(keys, sigs, vctx, &key);
+ 		svldr_key_del(&key);
+ 		if (ret == 0 || ret == kr_error(E2BIG)) {
+-			kr_assert(vctx->result == 0);
++			kr_assert(vctx->result == ret);
+ 			return vctx->result;
+ 		}
+ 	}
diff --git a/debian/patches/0013-daemon-more-avoidance-of-excessive-TCP-reconnections.patch b/debian/patches/0013-daemon-more-avoidance-of-excessive-TCP-reconnections.patch
new file mode 100644
index 0000000..fb1a3e4
--- /dev/null
+++ b/debian/patches/0013-daemon-more-avoidance-of-excessive-TCP-reconnections.patch
@@ -0,0 +1,153 @@
+From: =?utf-8?b?VmxhZGltw61yIMSMdW7DoXQ=?= <vladimir.cunat@nic.cz>
+Date: Sat, 29 Jul 2023 17:53:34 +0200
+Subject: daemon: more avoidance of excessive TCP reconnections
+
+Previously this penalization was only triggered if the remote server
+closed TCP.  Now it's extended to us closing it when the server
+(only) sends back some nonsense.  At least for the cases which I could
+see immediately.
+
+That's just three trivial one-line additions; the rest is refactoring.
+---
+ daemon/io.c      | 38 ++++++++++----------------------------
+ daemon/session.c | 26 +++++++++++++++++++++-----
+ daemon/session.h |  5 +++--
+ 3 files changed, 34 insertions(+), 35 deletions(-)
+
+diff --git a/daemon/io.c b/daemon/io.c
+index 48bfed3..ac0d969 100644
+--- a/daemon/io.c
++++ b/daemon/io.c
+@@ -337,33 +337,6 @@ void tcp_timeout_trigger(uv_timer_t *timer)
+ 	}
+ }
+ 
+-static void tcp_disconnect(struct session *s, int errcode)
+-{
+-	if (kr_log_is_debug(IO, NULL)) {
+-		struct sockaddr *peer = session_get_peer(s);
+-		char *peer_str = kr_straddr(peer);
+-		kr_log_debug(IO, "=> connection to '%s' closed by peer (%s)\n",
+-			       peer_str ? peer_str : "",
+-			       uv_strerror(errcode));
+-	}
+-
+-	if (!session_was_useful(s) && session_flags(s)->outgoing) {
+-		/* We want to penalize the IP address, if a task is asking a query.
+-		 * It might not be the right task, but that doesn't matter so much
+-		 * for attributing the useless session to the IP address. */
+-		struct qr_task *t = session_tasklist_get_first(s);
+-		struct kr_query *qry = NULL;
+-		if (t) {
+-			struct kr_request *req = worker_task_request(t);
+-			qry = array_tail(req->rplan.pending);
+-		}
+-		if (qry) /* We reuse the error for connection, as it's quite similar. */
+-			qry->server_selection.error(qry, worker_task_get_transport(t),
+-							KR_SELECTION_TCP_CONNECT_FAILED);
+-	}
+-	worker_end_tcp(s);
+-}
+-
+ static void tcp_recv(uv_stream_t *handle, ssize_t nread, const uv_buf_t *buf)
+ {
+ 	struct session *s = handle->data;
+@@ -381,7 +354,16 @@ static void tcp_recv(uv_stream_t *handle, ssize_t nread, const uv_buf_t *buf)
+ 	}
+ 
+ 	if (nread < 0 || !buf->base) {
+-		tcp_disconnect(s, nread);
++		if (kr_log_is_debug(IO, NULL)) {
++			struct sockaddr *peer = session_get_peer(s);
++			char *peer_str = kr_straddr(peer);
++			kr_log_debug(IO, "=> connection to '%s' closed by peer (%s)\n",
++				       peer_str ? peer_str : "",
++				       uv_strerror(nread));
++		}
++
++		session_tcp_penalize(s);
++		worker_end_tcp(s);
+ 		return;
+ 	}
+ 
+diff --git a/daemon/session.c b/daemon/session.c
+index a1f2207..ed0ff68 100644
+--- a/daemon/session.c
++++ b/daemon/session.c
+@@ -123,11 +123,6 @@ void session_close(struct session *session)
+ 	}
+ }
+ 
+-bool session_was_useful(const struct session *session)
+-{
+-	return session->was_useful;
+-}
+-
+ int session_start_read(struct session *session)
+ {
+ 	return io_start_read(session->handle);
+@@ -582,6 +577,24 @@ ssize_t session_wirebuf_trim(struct session *session, ssize_t len)
+ 	return len;
+ }
+ 
++void session_tcp_penalize(struct session *s)
++{
++	if (s->was_useful || !s->sflags.outgoing)
++		return;
++	/* We want to penalize the IP address, if a task is asking a query.
++	 * It might not be the right task, but that doesn't matter so much
++	 * for attributing the useless session to the IP address. */
++	struct qr_task *t = session_tasklist_get_first(s);
++	struct kr_query *qry = NULL;
++	if (t) {
++		struct kr_request *req = worker_task_request(t);
++		qry = array_tail(req->rplan.pending);
++	}
++	if (qry) /* We reuse the error for connection, as it's quite similar. */
++		qry->server_selection.error(qry, worker_task_get_transport(t),
++						KR_SELECTION_TCP_CONNECT_FAILED);
++}
++
+ knot_pkt_t *session_produce_packet(struct session *session, knot_mm_t *mm)
+ {
+ 	session->sflags.wirebuf_error = false;
+@@ -617,6 +630,7 @@ knot_pkt_t *session_produce_packet(struct session *session, knot_mm_t *mm)
+ 		msg_size = knot_wire_read_u16(msg_start);
+ 		if (msg_size >= session->wire_buf_size) {
+ 			session->sflags.wirebuf_error = true;
++			session_tcp_penalize(session);
+ 			return NULL;
+ 		}
+ 		if (msg_size + 2 > wirebuf_msg_data_size) {
+@@ -624,6 +638,7 @@ knot_pkt_t *session_produce_packet(struct session *session, knot_mm_t *mm)
+ 		}
+ 		if (msg_size == 0) {
+ 			session->sflags.wirebuf_error = true;
++			session_tcp_penalize(session);
+ 			return NULL;
+ 		}
+ 		msg_start += 2;
+@@ -631,6 +646,7 @@ knot_pkt_t *session_produce_packet(struct session *session, knot_mm_t *mm)
+ 		msg_size = wirebuf_msg_data_size;
+ 	} else {
+ 		session->sflags.wirebuf_error = true;
++		session_tcp_penalize(session);
+ 		return NULL;
+ 	}
+ 
+diff --git a/daemon/session.h b/daemon/session.h
+index 603d7cb..1f95ac5 100644
+--- a/daemon/session.h
++++ b/daemon/session.h
+@@ -91,8 +91,9 @@ int session_tasklist_finalize_expired(struct session *session);
+ /** Both of task lists (associated & waiting). */
+ /** Check if empty. */
+ bool session_is_empty(const struct session *session);
+-/** Return whether session seems to have done something useful. */
+-bool session_was_useful(const struct session *session);
++/** Penalize this server if the session hasn't been useful (and is outgoing). */
++void session_tcp_penalize(struct session *session);
++
+ /** Get pointer to session flags */
+ struct session_flags *session_flags(struct session *session);
+ /** Get pointer to peer address. */
diff --git a/debian/patches/series b/debian/patches/series
index 96443a0..e1ba371 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -1 +1,14 @@
+0001-validator-lower-the-NSEC3-iteration-limit-150-50.patch
+0002-validator-similarly-also-limit-excessive-NSEC3-salt-.patch
+0003-lib-cache-limit-the-amount-of-work-on-SHA1.patch
+0004-validator-limit-the-amount-of-work-on-SHA1-in-NSEC3-.patch
+0005-validator-refuse-to-validate-answers-with-more-than-.patch
+0006-validator-compatibility-with-older-libknot-versions.patch
+0007-lib-cache-bump-CACHE_VERSION.patch
+0008-lib-dnssec-kr_rrset_validate_with_key-deduplicate-cl.patch
+0009-lib-resolve-kr_request_set_extended_error-tweak-prio.patch
+0010-mitigate-KeyTrap-DoS-CVE-2023-50387.patch
+0011-mitigate-KeyTrap-DoS-CVE-2023-50387.patch
+0012-lib-dnssec-fix-imprecise-assertion.patch
+0013-daemon-more-avoidance-of-excessive-TCP-reconnections.patch
 progress-linux/0001-kresd-restart.patch
diff --git a/debian/salsa-ci.yml b/debian/salsa-ci.yml
index 984a817..b19fd28 100644
--- a/debian/salsa-ci.yml
+++ b/debian/salsa-ci.yml
@@ -3,5 +3,8 @@ include:
   - https://salsa.debian.org/salsa-ci-team/pipeline/raw/master/salsa-ci.yml
   - https://salsa.debian.org/salsa-ci-team/pipeline/raw/master/pipeline-jobs.yml
 
+variables:
+  RELEASE: 'bookworm'
+
 lintian:
   allow_failure: true