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Date: Mon, 8 Sep 2008 14:28:51 -0700
From: "Ranjit Manomohan" <ranjitm@...gle.com>
To: "Thomas Graf" <tgraf@...g.ch>
Cc: netdev@...r.kernel.org, "Paul Menage" <menage@...gle.com>
Subject: Re: [RFC] Control Group Classifier
On Mon, Sep 8, 2008 at 4:51 AM, Thomas Graf <tgraf@...g.ch> wrote:
> This patch implements a very basic cgroup subsystem which allows
> assigning classids to cgroups. It also adds a trivial classifier
> to filter packets based on that classid and map them to classes.
>
> The classifier should cover the most common use case and will work
> without any configuration. Additionaly it might make sense to add
> a cgroup meta ematch to allow for more sophisticated setups.
>
> I've taken over the idea of inheriting the classid of cgroup parents
> from the patchset posted by Ranjit Manomohan <ranjitm@...gle.com>.
>
> Comments welcome.
>
> Index: net-2.6-next/include/linux/cgroup_subsys.h
> ===================================================================
> --- net-2.6-next.orig/include/linux/cgroup_subsys.h 2008-09-08 13:38:07.000000000 +0200
> +++ net-2.6-next/include/linux/cgroup_subsys.h 2008-09-08 13:38:47.000000000 +0200
> @@ -48,3 +48,9 @@
> #endif
>
> /* */
> +
> +#ifdef CONFIG_NET_CLS_CGROUP
> +SUBSYS(net_cls)
> +#endif
> +
> +/* */
> Index: net-2.6-next/include/linux/pkt_cls.h
> ===================================================================
> --- net-2.6-next.orig/include/linux/pkt_cls.h 2008-09-08 13:38:07.000000000 +0200
> +++ net-2.6-next/include/linux/pkt_cls.h 2008-09-08 13:38:47.000000000 +0200
> @@ -394,6 +394,20 @@
>
> #define TCA_BASIC_MAX (__TCA_BASIC_MAX - 1)
>
> +
> +/* Cgroup classifier */
> +
> +enum
> +{
> + TCA_CGROUP_UNSPEC,
> + TCA_CGROUP_ACT,
> + TCA_CGROUP_POLICE,
> + TCA_CGROUP_EMATCHES,
> + __TCA_CGROUP_MAX,
> +};
> +
> +#define TCA_CGROUP_MAX (__TCA_CGROUP_MAX - 1)
> +
> /* Extended Matches */
>
> struct tcf_ematch_tree_hdr
> Index: net-2.6-next/net/sched/Kconfig
> ===================================================================
> --- net-2.6-next.orig/net/sched/Kconfig 2008-09-08 13:38:07.000000000 +0200
> +++ net-2.6-next/net/sched/Kconfig 2008-09-08 13:38:47.000000000 +0200
> @@ -307,6 +307,17 @@
> To compile this code as a module, choose M here: the
> module will be called cls_flow.
>
> +config NET_CLS_CGROUP
> + tristate "Control Group Classifier"
> + select NET_CLS
> + depends on CGROUPS
> + ---help---
> + Say Y here if you want to classify packets based on the control
> + cgroup of their process.
> +
> + To compile this code as a module, choose M here: the
> + module will be called cls_cgroup.
> +
> config NET_EMATCH
> bool "Extended Matches"
> select NET_CLS
> Index: net-2.6-next/net/sched/Makefile
> ===================================================================
> --- net-2.6-next.orig/net/sched/Makefile 2008-09-08 13:38:07.000000000 +0200
> +++ net-2.6-next/net/sched/Makefile 2008-09-08 13:38:47.000000000 +0200
> @@ -36,6 +36,7 @@
> obj-$(CONFIG_NET_CLS_RSVP6) += cls_rsvp6.o
> obj-$(CONFIG_NET_CLS_BASIC) += cls_basic.o
> obj-$(CONFIG_NET_CLS_FLOW) += cls_flow.o
> +obj-$(CONFIG_NET_CLS_CGROUP) += cls_cgroup.o
> obj-$(CONFIG_NET_EMATCH) += ematch.o
> obj-$(CONFIG_NET_EMATCH_CMP) += em_cmp.o
> obj-$(CONFIG_NET_EMATCH_NBYTE) += em_nbyte.o
> Index: net-2.6-next/net/sched/cls_cgroup.c
> ===================================================================
> --- /dev/null 1970-01-01 00:00:00.000000000 +0000
> +++ net-2.6-next/net/sched/cls_cgroup.c 2008-09-08 13:39:32.000000000 +0200
> @@ -0,0 +1,278 @@
> +/*
> + * net/sched/cls_cgroup.c Control Group Classifier
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; either version
> + * 2 of the License, or (at your option) any later version.
> + *
> + * Authors: Thomas Graf <tgraf@...g.ch>
> + */
> +
> +#include <linux/module.h>
> +#include <linux/types.h>
> +#include <linux/string.h>
> +#include <linux/errno.h>
> +#include <linux/skbuff.h>
> +#include <linux/cgroup.h>
> +#include <net/rtnetlink.h>
> +#include <net/pkt_cls.h>
> +
> +struct cgroup_cls_state
> +{
> + struct cgroup_subsys_state css;
> + u32 classid;
> +};
> +
> +static inline struct cgroup_cls_state *net_cls_state(struct cgroup *cgrp)
> +{
> + return (struct cgroup_cls_state *)
> + cgroup_subsys_state(cgrp, net_cls_subsys_id);
> +}
> +
> +static struct cgroup_subsys_state *cgrp_create(struct cgroup_subsys *ss,
> + struct cgroup *cgrp)
> +{
> + struct cgroup_cls_state *cs;
> +
> + if (!(cs = kzalloc(sizeof(*cs), GFP_KERNEL)))
> + return ERR_PTR(-ENOMEM);
> +
> + if (cgrp->parent)
> + cs->classid = net_cls_state(cgrp)->classid;
> +
> + return &cs->css;
> +}
> +
> +static void cgrp_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp)
> +{
> + kfree(ss);
> +}
> +
> +static u64 read_classid(struct cgroup *cgrp, struct cftype *cft)
> +{
> + return net_cls_state(cgrp)->classid;
> +}
> +
> +static int write_classid(struct cgroup *cgrp, struct cftype *cft, u64 value)
> +{
> + if (!cgroup_lock_live_group(cgrp))
> + return -ENODEV;
> +
> + net_cls_state(cgrp)->classid = (u32) value;
> +
> + cgroup_unlock();
> +
> + return 0;
> +}
> +
> +static struct cftype ss_files[] = {
> + {
> + .name = "classid",
> + .read_u64 = read_classid,
> + .write_u64 = write_classid,
> + },
> +};
> +
> +static int cgrp_populate(struct cgroup_subsys *ss, struct cgroup *cgrp)
> +{
> + return cgroup_add_files(cgrp, ss, ss_files, ARRAY_SIZE(ss_files));
> +}
> +
> +struct cgroup_subsys net_cls_subsys = {
> + .name = "net_cls",
> + .create = cgrp_create,
> + .destroy = cgrp_destroy,
> + .populate = cgrp_populate,
> + .subsys_id = net_cls_subsys_id,
> +};
> +
> +struct cls_cgroup_head
> +{
> + u32 handle;
> + struct tcf_exts exts;
> + struct tcf_ematch_tree ematches;
> +};
> +
> +static int cls_cgroup_classify(struct sk_buff *skb, struct tcf_proto *tp,
> + struct tcf_result *res)
> +{
> + struct cls_cgroup_head *head = tp->root;
> + struct cgroup_cls_state *cs;
> + int ret = 0;
> +
> + rcu_read_lock();
> +
> + cs = (struct cgroup_cls_state *) task_subsys_state(current,
> + net_cls_subsys_id);
Wouldn't this cause a lot of packets (like acks) to be incorrectly
classifed to the current tasks cgroup although it may not have
anything to do with them? That is the reason I chose to put the
classid into the socket at creation time.
-Thanks,
Ranjit
> + if (cs->classid && tcf_em_tree_match(skb, &head->ematches, NULL)) {
> + res->classid = cs->classid;
> + res->class = 0;
> + ret = tcf_exts_exec(skb, &head->exts, res);
> + } else
> + ret = -1;
> +
> + rcu_read_unlock();
> +
> + return ret;
> +}
> +
> +static unsigned long cls_cgroup_get(struct tcf_proto *tp, u32 handle)
> +{
> + return 0UL;
> +}
> +
> +static void cls_cgroup_put(struct tcf_proto *tp, unsigned long f)
> +{
> +}
> +
> +static int cls_cgroup_init(struct tcf_proto *tp)
> +{
> + return 0;
> +}
> +
> +static const struct tcf_ext_map cgroup_ext_map = {
> + .action = TCA_CGROUP_ACT,
> + .police = TCA_CGROUP_POLICE,
> +};
> +
> +static const struct nla_policy cgroup_policy[TCA_CGROUP_MAX + 1] = {
> + [TCA_CGROUP_EMATCHES] = { .type = NLA_NESTED },
> +};
> +
> +static int cls_cgroup_change(struct tcf_proto *tp, unsigned long base,
> + u32 handle, struct nlattr **tca,
> + unsigned long *arg)
> +{
> + struct nlattr *tb[TCA_CGROUP_MAX+1];
> + struct cls_cgroup_head *head = tp->root;
> + struct tcf_ematch_tree t;
> + struct tcf_exts e;
> + int err;
> +
> + if (head == NULL) {
> + if (!handle)
> + return -EINVAL;
> +
> + head = kzalloc(sizeof(*head), GFP_KERNEL);
> + if (head == NULL)
> + return -ENOBUFS;
> +
> + head->handle = handle;
> +
> + tcf_tree_lock(tp);
> + tp->root = head;
> + tcf_tree_unlock(tp);
> + }
> +
> + if (handle != head->handle)
> + return -ENOENT;
> +
> + err = nla_parse_nested(tb, TCA_CGROUP_MAX, tca[TCA_OPTIONS],
> + cgroup_policy);
> + if (err < 0)
> + return err;
> +
> + err = tcf_exts_validate(tp, tb, tca[TCA_RATE], &e, &cgroup_ext_map);
> + if (err < 0)
> + return err;
> +
> + err = tcf_em_tree_validate(tp, tb[TCA_CGROUP_EMATCHES], &t);
> + if (err < 0)
> + return err;
> +
> + tcf_exts_change(tp, &head->exts, &e);
> + tcf_em_tree_change(tp, &head->ematches, &t);
> +
> + return 0;
> +}
> +
> +static void cls_cgroup_destroy(struct tcf_proto *tp)
> +{
> + struct cls_cgroup_head *head;
> +
> + head = (struct cls_cgroup_head *)xchg(&tp->root, NULL);
> +
> + if (head) {
> + tcf_exts_destroy(tp, &head->exts);
> + tcf_em_tree_destroy(tp, &head->ematches);
> + kfree(head);
> + }
> +}
> +
> +static int cls_cgroup_delete(struct tcf_proto *tp, unsigned long arg)
> +{
> + return -EOPNOTSUPP;
> +}
> +
> +static void cls_cgroup_walk(struct tcf_proto *tp, struct tcf_walker *arg)
> +{
> + struct cls_cgroup_head *head = tp->root;
> +
> + if (arg->count < arg->skip)
> + goto skip;
> +
> + if (arg->fn(tp, (unsigned long) head, arg) < 0) {
> + arg->stop = 1;
> + return;
> + }
> +skip:
> + arg->count++;
> +}
> +
> +static int cls_cgroup_dump(struct tcf_proto *tp, unsigned long fh,
> + struct sk_buff *skb, struct tcmsg *t)
> +{
> + struct cls_cgroup_head *head = tp->root;
> + unsigned char *b = skb_tail_pointer(skb);
> + struct nlattr *nest;
> +
> + t->tcm_handle = head->handle;
> +
> + nest = nla_nest_start(skb, TCA_OPTIONS);
> + if (nest == NULL)
> + goto nla_put_failure;
> +
> + if (tcf_exts_dump(skb, &head->exts, &cgroup_ext_map) < 0 ||
> + tcf_em_tree_dump(skb, &head->ematches, TCA_CGROUP_EMATCHES) < 0)
> + goto nla_put_failure;
> +
> + nla_nest_end(skb, nest);
> +
> + if (tcf_exts_dump_stats(skb, &head->exts, &cgroup_ext_map) < 0)
> + goto nla_put_failure;
> +
> + return skb->len;
> +
> +nla_put_failure:
> + nlmsg_trim(skb, b);
> + return -1;
> +}
> +
> +static struct tcf_proto_ops cls_cgroup_ops __read_mostly = {
> + .kind = "cgroup",
> + .init = cls_cgroup_init,
> + .change = cls_cgroup_change,
> + .classify = cls_cgroup_classify,
> + .destroy = cls_cgroup_destroy,
> + .get = cls_cgroup_get,
> + .put = cls_cgroup_put,
> + .delete = cls_cgroup_delete,
> + .walk = cls_cgroup_walk,
> + .dump = cls_cgroup_dump,
> + .owner = THIS_MODULE,
> +};
> +
> +static int __init init_cgroup_cls(void)
> +{
> + return register_tcf_proto_ops(&cls_cgroup_ops);
> +}
> +
> +static void __exit exit_cgroup_cls(void)
> +{
> + unregister_tcf_proto_ops(&cls_cgroup_ops);
> +}
> +
> +module_init(init_cgroup_cls);
> +module_exit(exit_cgroup_cls);
> +MODULE_LICENSE("GPL");
> --
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