This bug was fixed in the package systemd - 240-6ubuntu5.8 --------------- systemd (240-6ubuntu5.8) disco; urgency=medium
[ Victor Tapia ] * d/p/resolved_disable-connection-downgrade-when-DNSSEC-yes.patch Fix regression introduced by resolved-Mitigate-DVE-2018-0001-by-retrying-NXDOMAIN-with.patch when DNSSEC=yes (LP: #1796501) [ Dan Streetman ] * d/p/lp1840640-shared-seccomp-add-sync_file_range2.patch: allow sync_file_range2 in nspawn container (LP: #1840640) * d/p/lp1847527-journal-remote-do-not-request-Content-Length-if-Tran.patch: do not request Content-Length if Transfer-Encoding is chunked (LP: #1847527) * d/t/storage: fix flaky test (LP: #1847815) * d/p/lp1843381-dell_passthrough_skip_rename_retry.patch, debian/extra/rules/73-usb-net-by-mac.rules: fix rename delay for systems using "Dell MAC passthrough" (LP: #1843381) * d/p/lp1849733/0001-resolved-if-we-can-t-append-EDNS-OPT-RR-then-indicat.patch, d/p/lp1849733/0002-resolved-don-t-let-EDNS0-OPT-dgram-size-affect-TCP.patch: ignore EDNS0 payload limit when responding over TCP (LP: #1849733) * d/p/lp1849658-resolved-set-stream-type-during-DnsStream-creation.patch: - Fix bug in refcounting TCP stream types (LP: #1849658) * d/extra/dhclient-enter-resolved-hook: - only restart resolved if dhclient conf changed (LP: #1805183) [ Balint Reczey ] * d/p/test-execute-Filter-dev-.lxc-in-exec-dynamicuser-statedir.patch: fix test breakage due to running in nested lxd container (LP: #1845337) -- Dan Streetman <ddstr...@canonical.com> Fri, 04 Oct 2019 09:06:58 -0400 ** Changed in: systemd (Ubuntu Disco) Status: Fix Committed => Fix Released -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to systemd in Ubuntu. https://bugs.launchpad.net/bugs/1796501 Title: systemd-resolved tries to mitigate DVE-2018-0001 even if DNSSEC=yes Status in systemd package in Ubuntu: Fix Released Status in systemd source package in Bionic: Fix Committed Status in systemd source package in Cosmic: Won't Fix Status in systemd source package in Disco: Fix Released Bug description: [impact] an NXDOMAIN response from a dns server when systemd-resolved is configured as DNSSEC=yes breaks dns resolution as it downgrades from DNSSEC. [test case] see comment 9 [regression potential] as with the original patch that introduced this problem, this has the potential to break dns resolution. [other info] original description: I ask systemd-resolved through dig to resolve the SOA of test.asdf. (doesn't exist) but it returns SERVFAIL instead of NXDOMAIN. It seems to do the following steps: 1. Ask upstream for SOA of test.asdf. with EDNS0, DO-bit and 4k size. 2. Ask upstream for SOA of test.asdf. with EDNS0 and DO-bit. 3. Ask upstream for SOA of test.asdf. with EDNS0. 4. Ask upstream for SOA of test.asdf. without EDNS0. 5. Repeat 1-4 for DS of test.asdf. 6. Repeat 1-5 for asdf. 7. Ask upstream for SOA of . with EDNS0, DO-bit and 4k size. 8. Ask upstream for DNSKEY of . with EDNS0, DO-bit and 4k size. The upstream returns an unfragmented NXDOMAIN response for steps 1-6, an unfragmented NOERROR response for step 7 and a fragmented NOERROR response for step 8 which is the correct behaviour. DNSSEC records are included in the response if the DO-bit in the request was set. systemd-resolved should take the response from step 1 and start with validation instead of starting useless retries with reduced feture set. Step 3 and 4 are completely useless and probably lead to the SERVFAIL because I have configured it with DNSSEC=yes to prevent downgrade attacks. This regression seems to be caused by the patch resolved-Mitigate- DVE-2018-0001-by-retrying-NXDOMAIN-with.patch. The downgrade logic should only be executed if it is configured as DNSSEC=allow-downgrade or DNSSEC=no. See also https://github.com/systemd/systemd/pull/8608#issuecomment-396927885. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1796501/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp