From f7b027e1a0dcdd2c92a5f3b1bcd488912389dca4 Mon Sep 17 00:00:00 2001 From: Jacek Migacz Date: Mon, 26 Feb 2024 14:07:37 +0100 Subject: [PATCH] resolved: reduce the maximum nsec3 iterations to 100 According to RFC9267, the 2500 value is not helpful, and in fact it can be harmful to permit a large number of iterations. Combined with limits on the number of signature validations, I expect this will mitigate the impact of maliciously crafted domains designed to cause excessive cryptographic work. (cherry picked from commit eba291124bc11f03732d1fc468db3bfac069f9cb) Related: RHEL-26643 --- src/resolve/resolved-dns-dnssec.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/src/resolve/resolved-dns-dnssec.c b/src/resolve/resolved-dns-dnssec.c index de2660e317..df25b7f619 100644 --- a/src/resolve/resolved-dns-dnssec.c +++ b/src/resolve/resolved-dns-dnssec.c @@ -27,8 +27,9 @@ DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(EC_KEY*, EC_KEY_free, NULL); /* Permit a maximum clock skew of 1h 10min. This should be enough to deal with DST confusion */ #define SKEW_MAX (1*USEC_PER_HOUR + 10*USEC_PER_MINUTE) -/* Maximum number of NSEC3 iterations we'll do. RFC5155 says 2500 shall be the maximum useful value */ -#define NSEC3_ITERATIONS_MAX 2500 +/* Maximum number of NSEC3 iterations we'll do. RFC5155 says 2500 shall be the maximum useful value, but + * RFC9276 ยง 3.2 says that we should reduce the acceptable iteration count */ +#define NSEC3_ITERATIONS_MAX 100 /* * The DNSSEC Chain of trust: