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7f3287db65
When running in container environmment, /sys/fs/cgroup/ might not be
the real root node of the sk-attached cgroup.
Example:
In container:
% stat /sys//fs/cgroup/
Device: 0,21 Inode: 2214 ..
% stat /sys/fs/cgroup/foo
Device: 0,21 Inode: 2264 ..
The expectation would be for:
nft add rule .. socket cgroupv2 level 1 "foo" counter
to match traffic from a process that got added to "foo" via
"echo $pid > /sys/fs/cgroup/foo/cgroup.procs".
However, 'level 3' is needed to make this work.
Seen from initial namespace, the complete hierarchy is:
% stat /sys/fs/cgroup/system.slice/docker-.../foo
Device: 0,21 Inode: 2264 ..
i.e. hierarchy is
0 1 2 3
/ -> system.slice -> docker-1... -> foo
... but the container doesn't know that its "/" is the "docker-1.."
cgroup. Current code will retrieve the 'system.slice' cgroup node
and store its kn->id in the destination register, so compare with
2264 ("foo" cgroup id) will not match.
Fetch "/" cgroup from ->init() and add its level to the level we try to
extract. cgroup root-level is 0 for the init-namespace or the level
of the ancestor that is exposed as the cgroup root inside the container.
In the above case, cgrp->level of "/" resolved in the container is 2
(docker-1...scope/) and request for 'level 1' will get adjusted
to fetch the actual level (3).
v2: use CONFIG_SOCK_CGROUP_DATA, eval function depends on it.
(kernel test robot)
Cc: cgroups@vger.kernel.org
Fixes: e0bb96db96 ("netfilter: nft_socket: add support for cgroupsv2")
Reported-by: Nadia Pinaeva <n.m.pinaeva@gmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.