resolved incorrectly limits TCP reply to edns0 payload
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
systemd (Ubuntu) |
Fix Released
|
Undecided
|
Unassigned | ||
Bionic |
Fix Released
|
Medium
|
Dan Streetman | ||
Disco |
Fix Released
|
Medium
|
Dan Streetman | ||
Eoan |
Fix Released
|
Medium
|
Dan Streetman |
Bug Description
[impact]
glibc's getaddrinfo() uses EDNS0 to talk to resolved, and it sets its payload limit to 1200. When the response is larger than 1200, resolved will limit the response and set the truncate flag. This causes getaddrinfo() to switch to TCP and request again, but glibc incorrectly keeps the EDNS0 RR opt, with the same 1200 payload limit. Most dns nameservers ignore EDNS0 payload limit for TCP, since per RFC it applies only to UDP, but resolved does not and again marks the response as truncated. This prevents getaddrinfo() from being able to resolve any records with a response over 1200 bytes.
[test case]
use ping or telnet, which use getaddrinfo(), to lookup an A record with a lot of results, like toomany100.
$ telnet toomany100.
telnet: could not resolve toomany100.
[regression potential]
any regression would likely result in failure to correctly lookup a hostname or to provide the correct response to a local client.
[other info]
note that on Bionic, this also requires backporting TCP pipelining support in the stub resolver.
Changed in systemd (Ubuntu Eoan): | |
status: | New → Fix Released |
Changed in systemd (Ubuntu Disco): | |
status: | New → In Progress |
Changed in systemd (Ubuntu Bionic): | |
status: | New → In Progress |
Changed in systemd (Ubuntu Disco): | |
importance: | Undecided → Medium |
Changed in systemd (Ubuntu Bionic): | |
importance: | Undecided → Medium |
Changed in systemd (Ubuntu Eoan): | |
importance: | Undecided → Medium |
assignee: | nobody → Dan Streetman (ddstreet) |
Changed in systemd (Ubuntu Disco): | |
assignee: | nobody → Dan Streetman (ddstreet) |
Changed in systemd (Ubuntu Bionic): | |
assignee: | nobody → Dan Streetman (ddstreet) |
Changed in systemd (Ubuntu): | |
status: | New → Fix Released |
tags: | added: bionic ddstreet disco eoan systemd |
tags: | removed: eoan |
description: | updated |
Hello Dan, or anyone else affected,
Accepted systemd into disco-proposed. The package will build now and be available at https:/ /launchpad. net/ubuntu/ +source/ systemd/ 240-6ubuntu5. 8 in a few hours, and then in the -proposed repository.
Please help us by testing this new package. See https:/ /wiki.ubuntu. com/Testing/ EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.
If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification- needed- disco to verification- done-disco. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification- failed- disco. In either case, without details of your testing we will not be able to proceed.
Further information regarding the verification process can be found at https:/ /wiki.ubuntu. com/QATeam/ PerformingSRUVe rification . Thank you in advance for helping!
N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.