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Bug 1255050 - Backport support for IFLA_LINK_NETNSID
Summary: Backport support for IFLA_LINK_NETNSID
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: libnl3
Version: 7.2
Hardware: Unspecified
OS: Unspecified
medium
medium
Target Milestone: rc
: ---
Assignee: Thomas Haller
QA Contact: Desktop QE
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2015-08-19 13:50 UTC by Thomas Haller
Modified: 2015-11-19 14:52 UTC (History)
4 users (show)

Fixed In Version: libnl3-3.2.21-9.el7
Doc Type: Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed: 2015-11-19 14:52:11 UTC
Target Upstream Version:
Embargoed:


Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHBA-2015:2105 0 normal SHIPPED_LIVE libnl3 bug fix update 2015-11-19 11:54:03 UTC

Description Thomas Haller 2015-08-19 13:50:20 UTC
Upstream kernel and libnl got support for IFLA_LINK_NETNS.

Backport the commits from upstream:
https://github.com/thom311/libnl/commit/8818a571e72c51bcda309d89bfaf93a2f5524d68
https://github.com/thom311/libnl/commit/fa380b409a02fe17b2d5cfc9074a8913523dbb68

Kernel already has support as of bug 1210260.



This is needed by NetworkManager to properly handle parent links in other netns.

Comment 2 Thomas Haller 2015-08-24 12:20:11 UTC
Explanation of this feature:

without this feature, libnl does not expose the IFLA_LINK_NETNSID attribute. That means, application who need this attribute, would have a hard time to work around it getting this information.

If an application (e.g. NetworkManager) is not aware of the IFLA_LINK_NETNSID, then it might wrongly think that the IFLA_LINK attribute advertised for a certain interface lies in it's own netns -- while in fact the ifindex in IFLA_LINK is only valid inside an other netns.


A common example are veth pairs, where one peer is in another netns of the application.
In this case, the IFLA_LINK of the visible peer is meaningless inside the netns of the application. Then the application either thinks that the linked-link is surprisingly missing, or it might wrongly think that it refers to another interface (that accidentally has an overlapping ifindex inside the netns of the application).


this can for example lead to wrong behavior inside NetworkManager.





Reproducer:

Create a veth pair and have their peers in two different netns. Make use of libnl3 and inspect the interface as returned from the library.
Check that the IFLA_LINK/rtnl_link_get_link() of that interface really shows the ifindex of the link in the other netns.
Check, that also  IFLA_LINK_NETNSID/rtnl_link_get_link_netnsid() indeed indicates that the link is in the other netnsid.

Comment 3 Thomas Haller 2015-08-25 17:46:15 UTC
The new API is disabled via

#ifdef NL_RHEL7_ENABLE_LINK_NETNSID

and only enabled for users who *really* need it.

Comment 6 errata-xmlrpc 2015-11-19 14:52:11 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, 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://rhn.redhat.com/errata/RHBA-2015-2105.html


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