[PATCH 2/2] Traffic control cgroups subsystem

From: Ranjit Manomohan
Date: Thu Aug 21 2008 - 20:58:16 EST


This patch implements a filter that classifies packets based upon
the cgroup_classid of the packet.

Signed-off-by: Ranjit Manomohan <ranjitm@xxxxxxxxxx>

---

diff --git a/include/linux/pkt_cls.h b/include/linux/pkt_cls.h
index 99efbed..53348a3 100644
--- a/include/linux/pkt_cls.h
+++ b/include/linux/pkt_cls.h
@@ -379,6 +379,21 @@ enum

#define TCA_FLOW_MAX (__TCA_FLOW_MAX - 1)

+/* Cgroups filter */
+
+enum {
+ TCA_CGROUP_UNSPEC,
+ TCA_CGROUP_CLASSID,
+ TCA_CGROUP_MASK,
+ TCA_CGROUP_VALUE,
+ TCA_CGROUP_ACT,
+ TCA_CGROUP_POLICE,
+ TCA_CGROUP_EMATCHES,
+ __TCA_CGROUP_MAX
+};
+
+#define TCA_CGROUP_MAX (__TCA_CGROUP_MAX - 1)
+
/* Basic filter */

enum
diff --git a/net/sched/Kconfig b/net/sched/Kconfig
index 82adfe6..844837f 100644
--- a/net/sched/Kconfig
+++ b/net/sched/Kconfig
@@ -318,6 +318,16 @@ config NET_CLS_FLOW
To compile this code as a module, choose M here: the
module will be called cls_flow.

+config NET_CLS_CGROUP
+ tristate "Cgroups tc classifier"
+ select NET_CLS
+ ---help---
+ If you say Y here, you will be able to classify packets based on
+ cgroup membership of the task originating the packet.
+
+ 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
diff --git a/net/sched/Makefile b/net/sched/Makefile
index 1d2b0f7..91e9ee0 100644
--- a/net/sched/Makefile
+++ b/net/sched/Makefile
@@ -36,6 +36,7 @@ obj-$(CONFIG_NET_CLS_TCINDEX) += cls_tcindex.o
obj-$(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
diff --git a/net/sched/cls_cgroup.c b/net/sched/cls_cgroup.c
new file mode 100644
index 0000000..70a363f
--- /dev/null
+++ b/net/sched/cls_cgroup.c
@@ -0,0 +1,330 @@
+/*
+ * net/sched/cls_cgroup.c Simple packet classifier which can filter
+ * packets based on the cgroups they belong to.
+ *
+ * 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.
+ *
+ */
+
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/skbuff.h>
+#include <net/pkt_cls.h>
+#include <net/netlink.h>
+#include <net/sock.h>
+
+struct cgroup_head {
+ struct list_head flist; /* Head of filter list */
+};
+
+struct cgroup_filter {
+ u32 handle; /* Unique filter handle */
+ struct tcf_exts exts;
+ struct tcf_ematch_tree ematches;
+ struct tcf_result res;
+ struct list_head link;
+ u32 mask;
+ u32 value;
+};
+
+static const struct tcf_ext_map cgroup_ext_map = {
+ .action = TCA_CGROUP_ACT,
+ .police = TCA_CGROUP_POLICE,
+};
+
+/* This function is called from the qdisc to classify a particular packet
+ * contained in the skb to the appropriate sub-classes. It returns the
+ * classid of the target class. This filter will match if the cgroup_classid
+ * in the skb matches the value in the filter.
+ */
+static int cgroup_classify(struct sk_buff *skb, struct tcf_proto *tp,
+ struct tcf_result *res)
+{
+ struct cgroup_head *head = (struct cgroup_head *)tp->root;
+ struct cgroup_filter *f;
+ uint32_t cgroup_classid = 0;
+ int r;
+
+#ifdef CONFIG_CGROUP_TC
+ if (skb->sk)
+ cgroup_classid = skb->sk->sk_cgroup_classid;
+#endif
+
+ list_for_each_entry(f, &head->flist, link) {
+
+ if (!tcf_em_tree_match(skb, &f->ematches, NULL))
+ continue;
+
+ if ((cgroup_classid & f->mask) == f->value) {
+ *res = f->res;
+ r = tcf_exts_exec(skb, &f->exts, res);
+ if (r < 0)
+ continue;
+ return r;
+ }
+ }
+ return -1;
+}
+
+/* Returns pointer to filter matching the handle passed into the function.*/
+static unsigned long cgroup_get(struct tcf_proto *tp, u32 handle)
+{
+ unsigned long l = 0UL;
+ struct cgroup_head *head = (struct cgroup_head *) tp->root;
+ struct cgroup_filter *f;
+
+ if (head == NULL)
+ return 0UL;
+
+ list_for_each_entry(f, &head->flist, link)
+ if (f->handle == handle)
+ l = (unsigned long) f;
+
+ return l;
+}
+
+/* Does not seem to be used for classifiers. */
+static void cgroup_put(struct tcf_proto *tp, unsigned long f)
+{
+}
+
+/* Initializer function called when tp is created. */
+static int cgroup_init(struct tcf_proto *tp)
+{
+ struct cgroup_head *head = kzalloc(sizeof(*head), GFP_KERNEL);
+ if (head == NULL)
+ return -ENOBUFS;
+
+ INIT_LIST_HEAD(&head->flist);
+ tp->root = head;
+ return 0;
+}
+
+/* Simple delete function called when filter is deleted */
+static inline void cgroup_delete_filter(struct tcf_proto *tp,
+ struct cgroup_filter *f)
+{
+ tcf_unbind_filter(tp, &f->res);
+ tcf_exts_destroy(tp, &f->exts);
+ tcf_em_tree_destroy(tp, &f->ematches);
+ kfree(f);
+}
+
+/* Destroy the entire tp structure.*/
+static void cgroup_destroy(struct tcf_proto *tp)
+{
+ struct cgroup_head *head = (struct cgroup_head *) xchg(&tp->root, NULL);
+ struct cgroup_filter *f, *n;
+
+ list_for_each_entry_safe(f, n, &head->flist, link) {
+ list_del(&f->link);
+ cgroup_delete_filter(tp, f);
+ }
+ kfree(head);
+}
+
+/* Delete one filter entry */
+static int cgroup_delete(struct tcf_proto *tp, unsigned long arg)
+{
+ struct cgroup_head *head = (struct cgroup_head *) tp->root;
+ struct cgroup_filter *t, *f = (struct cgroup_filter *) arg;
+
+ list_for_each_entry(t, &head->flist, link)
+ if (t == f) {
+ tcf_tree_lock(tp);
+ list_del(&t->link);
+ tcf_tree_unlock(tp);
+ cgroup_delete_filter(tp, t);
+ return 0;
+ }
+
+ return -ENOENT;
+}
+
+/* Set the mask and value parameters in the tp structure. */
+static inline int cgroup_set_parms(struct tcf_proto *tp,
+ unsigned long base,
+ struct cgroup_filter *f, struct nlattr **tb)
+{
+ int err = -EINVAL;
+
+ if (tb[TCA_CGROUP_MASK]) {
+ if (nla_len(tb[TCA_CGROUP_MASK]) < sizeof(u32))
+ return err;
+ f->mask = nla_get_u32(tb[TCA_CGROUP_MASK]);
+ } else
+ f->mask = UINT_MAX;
+
+ if (tb[TCA_CGROUP_VALUE]) {
+ if (nla_len(tb[TCA_CGROUP_VALUE]) < sizeof(u32))
+ return err;
+ f->value = nla_get_u32(tb[TCA_CGROUP_VALUE]);
+ } else
+ return err;
+
+ if (tb[TCA_CGROUP_CLASSID]) {
+ if (nla_len(tb[TCA_CGROUP_CLASSID]) < sizeof(u32))
+ return err;
+ f->res.classid = nla_get_u32(tb[TCA_CGROUP_CLASSID]);
+ tcf_bind_filter(tp, &f->res, base);
+ } else
+ return err;
+
+ return 0;
+}
+
+/* Change the mask and value parameters in the current settings. */
+static int cgroup_change(struct tcf_proto *tp, unsigned long base, u32 handle,
+ struct nlattr **tca, unsigned long *arg)
+{
+ int err = -EINVAL;
+ struct cgroup_head *head = (struct cgroup_head *) tp->root;
+ struct nlattr *tb[TCA_CGROUP_MAX];
+ struct cgroup_filter *f = (struct cgroup_filter *) *arg;
+ struct tcf_exts e;
+ struct tcf_ematch_tree t;
+
+ if (tca[TCA_OPTIONS] == NULL)
+ return -EINVAL;
+
+ if (nla_parse_nested(tb, TCA_CGROUP_MAX, tca[TCA_OPTIONS], NULL) < 0)
+ return -EINVAL;
+
+ 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)
+ goto error1;
+
+ if (f != NULL) {
+ if (handle && f->handle != handle)
+ goto error2;
+ } else {
+ if (!handle)
+ goto error2;
+ f = kzalloc(sizeof(*f), GFP_KERNEL);
+ if (f == NULL)
+ goto error2;
+ f->handle = handle;
+ }
+
+ err = cgroup_set_parms(tp, base, f, tb);
+ if (err < 0)
+ goto error3;
+
+ tcf_exts_change(tp, &f->exts, &e);
+ tcf_em_tree_change(tp, &f->ematches, &t);
+
+ if (*arg == 0) {
+ tcf_tree_lock(tp);
+ list_add(&f->link, &head->flist);
+ tcf_tree_unlock(tp);
+ }
+
+ *arg = (unsigned long)f;
+ return 0;
+
+error3:
+ if (*arg == 0)
+ kfree(f);
+error2:
+ tcf_em_tree_destroy(tp, &t);
+error1:
+ tcf_exts_destroy(tp, &e);
+
+ return err;
+}
+
+/* Walk the filter list for things like displaying contents.*/
+static void cgroup_walk(struct tcf_proto *tp, struct tcf_walker *arg)
+{
+ struct cgroup_head *head = (struct cgroup_head *) tp->root;
+ struct cgroup_filter *f;
+
+ list_for_each_entry(f, &head->flist, link) {
+ if (arg->count < arg->skip)
+ goto skip;
+
+ if (arg->fn(tp, (unsigned long) f, arg) < 0) {
+ arg->stop = 1;
+ break;
+ }
+skip:
+ arg->count++;
+ }
+}
+
+/* Retreive current settings in the filter */
+static int cgroup_dump(struct tcf_proto *tp, unsigned long fh,
+ struct sk_buff *skb, struct tcmsg *t)
+{
+ struct cgroup_filter *f = (struct cgroup_filter *) fh;
+ struct nlattr *nest;
+
+ if (f == NULL)
+ return skb->len;
+
+ t->tcm_handle = f->handle;
+
+ nest = nla_nest_start(skb, TCA_OPTIONS);
+ if (nest == NULL)
+ goto nla_put_failure;
+
+ NLA_PUT_U32(skb, TCA_CGROUP_CLASSID, f->res.classid);
+ NLA_PUT_U32(skb, TCA_CGROUP_MASK, f->mask);
+ NLA_PUT_U32(skb, TCA_CGROUP_VALUE, f->value);
+
+ if (tcf_exts_dump(skb, &f->exts, &cgroup_ext_map) < 0)
+ goto nla_put_failure;
+
+#ifdef CONFIG_NET_EMATCH
+ if (f->ematches.hdr.nmatches &&
+ tcf_em_tree_dump(skb, &f->ematches, TCA_CGROUP_EMATCHES) < 0)
+ goto nla_put_failure;
+#endif
+
+ if (tcf_exts_dump_stats(skb, &f->exts, &cgroup_ext_map) < 0)
+ goto nla_put_failure;
+
+ nla_nest_end(skb, nest);
+ return skb->len;
+
+nla_put_failure:
+ nla_nest_cancel(skb, nest);
+ return -1;
+}
+
+static struct tcf_proto_ops cls_cgroup_ops = {
+ .kind = "cgroup",
+ .classify = cgroup_classify,
+ .init = cgroup_init,
+ .destroy = cgroup_destroy,
+ .get = cgroup_get,
+ .put = cgroup_put,
+ .change = cgroup_change,
+ .delete = cgroup_delete,
+ .walk = cgroup_walk,
+ .dump = cgroup_dump,
+ .owner = THIS_MODULE,
+};
+
+static int __init init_cgroup(void)
+{
+ return register_tcf_proto_ops(&cls_cgroup_ops);
+}
+
+static void __exit exit_cgroup(void)
+{
+ unregister_tcf_proto_ops(&cls_cgroup_ops);
+}
+
+module_init(init_cgroup)
+module_exit(exit_cgroup)
+MODULE_LICENSE("GPL");
+
--
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