Hello, In cgroup v1, dealing with cgroup membership was difficult because the number of membership associations was unbound. As a result, cgroup v1 grew several controllers whose primary purpose is either tagging membership or pull in configuration knobs from other subsystems so that cgroup membership test can be avoided. net_cls and net_prio controllers are examples of the latter. They allow configuring network-specific attributes from cgroup side so that network subsystem can avoid testing cgroup membership; unfortunately, these are not only cumbersome but also problematic. Both net_cls and net_prio aren't properly hierarchical. Both inherit configuration from the parent on creation but there's no interaction afterwards. An ancestor doesn't restrict the behavior in its subtree in anyway and configuration changes aren't propagated downwards. Especially when combined with cgroup delegation, this is problematic because delegatees can mess up whatever network configuration implemented at the system level. net_prio would allow the delegatees to set whatever priority value regardless of CAP_NET_ADMIN and net_cls the same for classid. While it is possible to solve these issues from controller side by implementing hierarchical allowable ranges in both controllers, it would involve quite a bit of complexity in the controllers and further obfuscate network configuration as it becomes even more difficult to tell what's actually being configured looking from the network side. While not much can be done for v1 at this point, as membership handling is sane on cgroup v2, it'd be better to make cgroup matching behave like other network matches and classifiers than introducing further complications. Unfortunately, this ends up adding another cgroup related field to struct sock - sock->sk_cgroup. I tried to think of a way to overload the fields for net_cls and net_prio but couldn't come up with a sane way to do that. In the long term, it should be possible to disable net_cls and net_prio. This patchset includes the following five patches. 0001-cgroup-record-ancestor-IDs-and-reimplement-cgroup_is.patch 0002-kernfs-implement-kernfs_walk_and_get.patch 0003-cgroup-implement-cgroup_get_from_path-and-expose-cgr.patch 0004-sock-cgroup-add-sock-sk_cgroup.patch 0005-netfilter-implement-xt_cgroup2-match.patch 0001-0003 are prepatory patches in kernfs and cgroup. 0004 adds sock->sk_cgroup to track socket to cgroup association. 0005 implements the new xt_cgroup2 match. This patchset is on top of v4.4-rc1 and also available in the following git branch. git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git review-xt_cgroup2 I'll post iptables extension as a reply. diffstat follows. Thanks. fs/kernfs/dir.c | 48 +++++++++++++++ include/linux/cgroup-defs.h | 14 ++++ include/linux/cgroup.h | 33 ++++++++++ include/linux/kernfs.h | 12 +++ include/net/sock.h | 4 + include/uapi/linux/netfilter/xt_cgroup2.h | 14 ++++ kernel/cgroup.c | 95 +++++++++++++++++++++--------- net/core/sock.c | 2 net/netfilter/Kconfig | 9 ++ net/netfilter/Makefile | 1 net/netfilter/xt_cgroup2.c | 75 +++++++++++++++++++++++ 11 files changed, 278 insertions(+), 29 deletions(-) -- tejun -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
