Sha1 runtime insecure

[pemensik]

Attempt to solve issue #656

Fallback from bogus to insecure, if crypto library returned specific error during verification.

[pemensik]

Any comments for this change?

[gthess]

As I understand this is also related to FIPS. Why not just do something similar as #671 with detecting FIPS mode for the digest? Then we won't have to rely on the openssl error code for detection (which I cannot find proper documentation for its actual meaning and the stability of its use).

[pemensik]

The reason for it is simple. It does happen on CentOS 9 Stream and RHEL 9 in default installation. Unlike PR #671 this does not fail only when FIPS mode is enabled. It fails also when DEFAULT crypto-policy is set. Which is preselected policy on mentioned distributions.

Of course it would fail in FIPS mode too. But it is more general, because it has to be. There's a note about that in Considerations in adopting RHEL 9. And related release note mention that unbound package build currently disables all SHA-1 validation in all cases. This change would allow secure resolution of SHA-1 base name in legacy policies, but at least insecure resolution in default policy or FIPS mode.

There is pull request to enable simple check to openssl, but until that is present in openssl, it is not that simple.

Also it is good to note, it would affect both our official packages and also unofficial builds, as long as they link to openssl.

[pemensik]

How to check this with simple steps:

# podman run -ti quay.io/centos/centos:stream9
# dnf install -y unbound
# unbound-host -rvD ietf.org
ietf.org has address 50.223.129.194 (insecure)
ietf.org has IPv6 address 2001:559:c4c7::100 (insecure)
ietf.org mail is handled by 0 mail.ietf.org. (insecure)
# dnf install -y bind-utils
# delv ietf.org
;; EVP_VerifyFinal failed (verify failure)
;; error:03000098:digital envelope routines::invalid digest:crypto/evp/pmeth_lib.c:959:
;; EVP_VerifyFinal failed (verify failure)
;; error:03000098:digital envelope routines::invalid digest:crypto/evp/pmeth_lib.c:959:
;; EVP_VerifyFinal failed (verify failure)
;; error:03000098:digital envelope routines::invalid digest:crypto/evp/pmeth_lib.c:959:
;; EVP_VerifyFinal failed (verify failure)
;; error:03000098:digital envelope routines::invalid digest:crypto/evp/pmeth_lib.c:959:
;; validating ietf.org/DNSKEY: no valid signature found
;; insecurity proof failed resolving 'ietf.org/DNSKEY/IN': 8.8.4.4#53
;; EVP_VerifyFinal failed (verify failure)
;; error:03000098:digital envelope routines::invalid digest:crypto/evp/pmeth_lib.c:959:
;; EVP_VerifyFinal failed (verify failure)
;; error:03000098:digital envelope routines::invalid digest:crypto/evp/pmeth_lib.c:959:
;; EVP_VerifyFinal failed (verify failure)
;; error:03000098:digital envelope routines::invalid digest:crypto/evp/pmeth_lib.c:959:
;; EVP_VerifyFinal failed (verify failure)
;; error:03000098:digital envelope routines::invalid digest:crypto/evp/pmeth_lib.c:959:
;; validating ietf.org/DNSKEY: no valid signature found
;; no valid RRSIG resolving 'ietf.org/DNSKEY/IN': 8.8.8.8#53
;; EVP_VerifyFinal failed (verify failure)
;; error:03000098:digital envelope routines::invalid digest:crypto/evp/pmeth_lib.c:959:
;; EVP_VerifyFinal failed (verify failure)
;; error:03000098:digital envelope routines::invalid digest:crypto/evp/pmeth_lib.c:959:
;; EVP_VerifyFinal failed (verify failure)
;; error:03000098:digital envelope routines::invalid digest:crypto/evp/pmeth_lib.c:959:
;; EVP_VerifyFinal failed (verify failure)
;; error:03000098:digital envelope routines::invalid digest:crypto/evp/pmeth_lib.c:959:
;; validating ietf.org/DNSKEY: no valid signature found
;; no valid RRSIG resolving 'ietf.org/DNSKEY/IN': 10.0.2.3#53
;; broken trust chain resolving 'ietf.org/A/IN': 10.0.2.3#53
;; resolution failed: broken trust chain
# update-crypto-policies --set DEFAULT:SHA1
# delv ietf.org
; fully validated
ietf.org.		179	IN	A	50.223.129.194
ietf.org.		179	IN	RRSIG	A 5 2 1800 20230512164317 20220512154550 40452 ietf.org. ujh5zmVnBEGATtJu4Or8Aw4Y2mY2d9AFZLHj2qzgD5pDMyfnUeVRIHui IyEhzAHS7sSVOoBg9gXYr//Ol+i0TWc2UTTXwDwZ7iCzSiOdkxSA+CWJ LI4biOi1CR2ypjQAiuOzVRDCOUD1b8zE9z8PUhdWo0J271QqrQ7jMUzZ CTl6mnpgK0eLiY4Yuf1TbE6F7Adl5Yg6YQYq+OBa+1Aeaso/n+jcSgm2 nkHiLTVqUfj3xrCn/KfFTyPi1q3Gb2wnqZQkRBrYvnaoHdRmt1fzw7sf furzw4MbWkCu+jOaVVO74PQ8sCmEABcCjP/3czEVQ6+F4rmpTakrI/x3 QSYFmQ==
# echo "Now unbound-host could return secure result with this change"

Replace podman with docker if you wish.