[Backport][ipa-4-8] CVE-2020-1722: prevent use of too long passwords #4526
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NIST SP 800-63-3B sets a recommendation to have password length upper bound limited in A.2: https://pages.nist.gov/800-63-3/sp800-63b.html#appA Users should be encouraged to make their passwords as lengthy as they want, within reason. Since the size of a hashed password is independent of its length, there is no reason not to permit the use of lengthy passwords (or pass phrases) if the user wishes. Extremely long passwords (perhaps megabytes in length) could conceivably require excessive processing time to hash, so it is reasonable to have some limit. FreeIPA already applied 256 characters limit for non-random passwords set through ipa-getkeytab tool. The limit was not, however, enforced in other places. MIT Kerberos limits the length of the password to 1024 characters in its tools. However, these tools (kpasswd and 'cpw' command of kadmin) do not differentiate between a password larger than 1024 and a password of 1024 characters. As a result, longer passwords are silently cut off. To prevent silent cut off for user passwords, use limit of 1000 characters. Thus, this patch enforces common limit of 1000 characters everywhere: - LDAP-based password changes - LDAP password change control - LDAP ADD and MOD operations on clear-text userPassword - Keytab setting with ipa-getkeytab - Kerberos password setting and changing Fixes: https://pagure.io/freeipa/issue/8268 Signed-off-by: Alexander Bokovoy <abokovoy@redhat.com> Signed-off-by: Rob Crittenden <rcritten@redhat.com> Reviewed-by: Simo Sorce <ssorce@redhat.com>
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This PR was opened automatically because PR #4525 was pushed to master and backport to ipa-4-8 is required.