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Bug 1737910 - Name Constraints validation: CN treated as DNS name even when syntactically invalid as DNS name [rhel-7.9.z]
Summary: Name Constraints validation: CN treated as DNS name even when syntactically i...
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: nss
Version: 7.7
Hardware: All
OS: Linux
urgent
high
Target Milestone: rc
: ---
Assignee: Bob Relyea
QA Contact: Alicja Kario
URL:
Whiteboard:
Depends On: 1804262
Blocks: 1825270
TreeView+ depends on / blocked
 
Reported: 2019-08-06 11:31 UTC by Fraser Tweedale
Modified: 2022-11-14 09:40 UTC (History)
13 users (show)

Fixed In Version: nss-3.53.1-3.el7_9
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
: 1825270 (view as bug list)
Environment:
Last Closed: 2020-09-29 21:18:42 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Mozilla Foundation 1571677 0 P2 ASSIGNED Name Constraints validation: CN treated as DNS name even when syntactically invalid as DNS name 2021-02-15 15:09:59 UTC
Red Hat Bugzilla 1670239 0 urgent CLOSED libpkix name constraints check treats CN as DNS name when it should not 2021-02-22 00:41:40 UTC
Red Hat Product Errata RHSA-2020:4076 0 None None None 2020-09-29 21:19:20 UTC

Description Fraser Tweedale 2019-08-06 11:31:11 UTC 
Description of problem:

Client certificate verification, where client cert has "CN=IPA RA,O=IPA.LOCAL", EKU with id-kp-serverAuth and id-kp-clientAuth, and no SAN. Issuer has DNS Name Constraint permittedSubtree of "ipa.local".


Actual results:

Certificate verification fails due to name constraint violation.


Expected results:

This bug is on similar lines to https://bugzilla.mozilla.org/show_bug.cgi?id=1523484 / https://bugzilla.redhat.com/show_bug.cgi?id=1670239, but a different issue. The CN is syntactically not a valid DNS name. Therefore the "treat CN as a DNS name" heuristic should not apply in this case. Certificate verification should succeed.


Additional info:

Upstream BZ: https://bugzilla.mozilla.org/show_bug.cgi?id=1571677
Comment 2 Alicja Kario 2019-08-06 14:24:51 UTC 
Reproducer:
# get a helper library
git clone https://github.com/redhat-qe-security/certgen.git
. certgen/certgen/lib.sh
# generate the certificates
x509KeyGen ca
x509KeyGen server
x509KeyGen client
x509SelfSign --ncExclude '.com' --ncPermit localhost ca

x509CertSign --CA ca server
x509CertSign --CA ca -t webclient \
--extendedKeyUsage serverAuth,clientAuth,emailProtection client
# print the generated certificates
x509DumpCert ca
x509DumpCert server
x509DumpCert client

# set up the NSS databases for client and server
mkdir nssdb-srv
mkdir nssdb-clnt
certutil -N -d nssdb-srv/ --empty-password
certutil -N -d nssdb-clnt --empty-password
certutil -A -n ca -i $(x509Cert ca) -t 'cTC,cTC,' -a -d nssdb-srv
certutil -A -n ca -i $(x509Cert ca) -t 'cTC,cTC,' -a -d nssdb-clnt
pk12util -d nssdb-srv -i $(x509Key --with-cert --pkcs12 server) -W ''
pk12util -d nssdb-clnt -i $(x509Key --with-cert --pkcs12 client) -W ''

# start server that requires client certificates
NSS_ENABLE_PKIX_VERIFY=1 /usr/lib64/nss/unsupported-tools/selfserv -d nssdb-srv -p 4433 -V tls1.2: \
-H 1 -n server -rr -v

#!! run in separate console, same directory
# client that will trust the server cert and has a certificate trusted by 
# server:
SSL_DIR=nssdb-clnt curl https://localhost:4433
# or using tstclnt:
tstclnt -d nssdb-clnt -h localhost -p 4433 -n client <<<"GET / HTTP/1.0

"
Comment 4 Fraser Tweedale 2019-08-07 04:26:00 UTC 
I've tested Bob's patch, it works correctly.
Comment 7 Bob Relyea 2019-08-07 20:09:55 UTC 
Builds with fix: nss-3.44.0-5.el7
https://brewweb.engineering.redhat.com/brew/buildinfo?buildID=945972

I'm not sure who handles the hotfix portion of this..

bob
Comment 48 errata-xmlrpc 2020-09-29 21:18:42 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (Moderate: nss and nspr security, bug fix, and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHSA-2020:4076
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