Launchpad doesn't support secure SSH parameters

Bug #1933722 reported by Sam Bull
8
This bug affects 1 person
Affects Status Importance Assigned to Milestone
Launchpad itself
Fix Released
High
Colin Watson
lazr.sshserver
Fix Released
High
Colin Watson
turnip
Fix Released
High
Colin Watson
txpkgupload
Fix Released
High
Colin Watson

Bug Description

With a secure config created for SSH, I am unable to connect without adding a weakened config for launchpad.

For example:
Unable to negotiate with 91.189.95.84 port 22: no matching host key type found. Their offer: ssh-rsa

ssh-rsa is considered insecure, enough that I believe it has been disabled by default in openssh now. Maybe it should be disabled for LP, but it certainly shouldn't be the ONLY option for connecting. This is currently required for both HostKeyAlgorithms and PubkeyAcceptedKeyTypes.

Additionally, I need to add hmac-sha2-512 to MACs, because LP doesn't support any etm versions, for example: <email address hidden> or <email address hidden>

Related branches

Sam Bull (dreamsorcerer)
description: updated
Revision history for this message
Colin Watson (cjwatson) wrote :

This mainly needs to be fixed in Twisted upstream, but the key algorithm types will probably also then need some enablement work in lazr.sshserver. And then we'll have somewhat similar problems as in bug 907675, in that we need to finish the upgrade to Python 3 and also upgrade to Ubuntu 18.04 in order to be able to use recent upstream versions of Twisted.

affects: launchpad → lazr.sshserver
Revision history for this message
Colin Watson (cjwatson) wrote :

I'm fairly sure you're mistaken about ssh-rsa having been disabled in OpenSSH, by the way. They've been issuing "future deprecation notices" about it for some time, but haven't actually turned it off yet.

Changed in lazr.sshserver:
status: New → Triaged
importance: Undecided → High
Revision history for this message
Colin Watson (cjwatson) wrote :

lazr.sshserver 0.1.13 and the backports of assorted Twisted changes in https://code.launchpad.net/~cjwatson/twisted/+git/twisted/+merge/415186 fix this. We now just need to integrate these into our various endpoints.

Changed in launchpad:
status: New → Triaged
importance: Undecided → High
Changed in turnip:
status: New → Triaged
importance: Undecided → High
Changed in txpkgupload:
status: New → Triaged
importance: Undecided → High
Changed in lazr.sshserver:
assignee: nobody → Colin Watson (cjwatson)
status: Triaged → Fix Released
Revision history for this message
Colin Watson (cjwatson) wrote :

upload.ubuntu.com and ppa.launchpad.net now support RSA SHA-2 signatures.

Changed in txpkgupload:
assignee: nobody → Colin Watson (cjwatson)
status: Triaged → Fix Released
Revision history for this message
Colin Watson (cjwatson) wrote :

git.launchpad.net now supports RSA SHA-2 signatures.

Changed in turnip:
assignee: nobody → Colin Watson (cjwatson)
status: Triaged → Fix Released
Revision history for this message
Colin Watson (cjwatson) wrote :

We had to revert the deployment to upload.ubuntu.com/ppa.launchpad.net due to a regression (I think unrelated, but we haven't tracked it down yet). Sorting this out will be a high priority.

Changed in txpkgupload:
status: Fix Released → In Progress
Revision history for this message
Colin Watson (cjwatson) wrote :

bazaar.launchpad.net now supports RSA SHA-2 signatures (in fact rolled out on 2022-02-11, but I forgot to close this bug).

Changed in launchpad:
assignee: nobody → Colin Watson (cjwatson)
status: Triaged → Fix Released
Revision history for this message
Colin Watson (cjwatson) wrote :

upload.ubuntu.com and ppa.launchpad.net now support RSA SHA-2 signatures again, fixing the regression we ran into (https://twistedmatrix.com/trac/ticket/10308). That completes this bug.

Changed in txpkgupload:
status: In Progress → Fix Released
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