diff options
Diffstat (limited to 'debian/patches/0003-lib-cache-limit-the-amount-of-work-on-SHA1.patch')
| -rw-r--r-- | debian/patches/0003-lib-cache-limit-the-amount-of-work-on-SHA1.patch | 60 |
1 files changed, 60 insertions, 0 deletions
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). |