![John Fastabend](/assets/img/avatar_default.png)
It is not RCU safe to destroy the action chain while there is a possibility of readers accessing it. Move this code into the rcu callback using the same rcu callback used in the code patch to make a change to head. Signed-off-by: John Fastabend <john.r.fastabend@intel.com> Acked-by: Cong Wang <cwang@twopensource.com> Signed-off-by: David S. Miller <davem@davemloft.net>
240 lines
5.5 KiB
C
240 lines
5.5 KiB
C
/*
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* net/sched/cls_cgroup.c Control Group Classifier
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* Authors: Thomas Graf <tgraf@suug.ch>
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*/
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/skbuff.h>
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#include <linux/rcupdate.h>
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#include <net/rtnetlink.h>
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#include <net/pkt_cls.h>
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#include <net/sock.h>
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#include <net/cls_cgroup.h>
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struct cls_cgroup_head {
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u32 handle;
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struct tcf_exts exts;
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struct tcf_ematch_tree ematches;
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struct tcf_proto *tp;
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struct rcu_head rcu;
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};
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static int cls_cgroup_classify(struct sk_buff *skb, const struct tcf_proto *tp,
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struct tcf_result *res)
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{
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struct cls_cgroup_head *head = rcu_dereference_bh(tp->root);
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u32 classid;
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classid = task_cls_state(current)->classid;
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/*
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* Due to the nature of the classifier it is required to ignore all
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* packets originating from softirq context as accessing `current'
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* would lead to false results.
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*
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* This test assumes that all callers of dev_queue_xmit() explicitely
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* disable bh. Knowing this, it is possible to detect softirq based
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* calls by looking at the number of nested bh disable calls because
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* softirqs always disables bh.
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*/
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if (in_serving_softirq()) {
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/* If there is an sk_classid we'll use that. */
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if (!skb->sk)
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return -1;
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classid = skb->sk->sk_classid;
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}
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if (!classid)
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return -1;
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if (!tcf_em_tree_match(skb, &head->ematches, NULL))
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return -1;
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res->classid = classid;
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res->class = 0;
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return tcf_exts_exec(skb, &head->exts, res);
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}
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static unsigned long cls_cgroup_get(struct tcf_proto *tp, u32 handle)
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{
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return 0UL;
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}
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static void cls_cgroup_put(struct tcf_proto *tp, unsigned long f)
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{
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}
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static int cls_cgroup_init(struct tcf_proto *tp)
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{
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return 0;
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}
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static const struct nla_policy cgroup_policy[TCA_CGROUP_MAX + 1] = {
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[TCA_CGROUP_EMATCHES] = { .type = NLA_NESTED },
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};
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static void cls_cgroup_destroy_rcu(struct rcu_head *root)
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{
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struct cls_cgroup_head *head = container_of(root,
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struct cls_cgroup_head,
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rcu);
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tcf_exts_destroy(&head->exts);
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tcf_em_tree_destroy(&head->ematches);
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kfree(head);
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}
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static int cls_cgroup_change(struct net *net, struct sk_buff *in_skb,
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struct tcf_proto *tp, unsigned long base,
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u32 handle, struct nlattr **tca,
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unsigned long *arg, bool ovr)
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{
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struct nlattr *tb[TCA_CGROUP_MAX + 1];
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struct cls_cgroup_head *head = rtnl_dereference(tp->root);
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struct cls_cgroup_head *new;
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struct tcf_ematch_tree t;
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struct tcf_exts e;
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int err;
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if (!tca[TCA_OPTIONS])
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return -EINVAL;
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if (!head && !handle)
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return -EINVAL;
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if (head && handle != head->handle)
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return -ENOENT;
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new = kzalloc(sizeof(*head), GFP_KERNEL);
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if (!new)
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return -ENOBUFS;
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tcf_exts_init(&new->exts, TCA_CGROUP_ACT, TCA_CGROUP_POLICE);
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if (head)
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new->handle = head->handle;
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else
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new->handle = handle;
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new->tp = tp;
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err = nla_parse_nested(tb, TCA_CGROUP_MAX, tca[TCA_OPTIONS],
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cgroup_policy);
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if (err < 0)
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goto errout;
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tcf_exts_init(&e, TCA_CGROUP_ACT, TCA_CGROUP_POLICE);
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err = tcf_exts_validate(net, tp, tb, tca[TCA_RATE], &e, ovr);
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if (err < 0)
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goto errout;
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err = tcf_em_tree_validate(tp, tb[TCA_CGROUP_EMATCHES], &t);
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if (err < 0) {
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tcf_exts_destroy(&e);
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goto errout;
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}
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tcf_exts_change(tp, &new->exts, &e);
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tcf_em_tree_change(tp, &new->ematches, &t);
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rcu_assign_pointer(tp->root, new);
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if (head)
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call_rcu(&head->rcu, cls_cgroup_destroy_rcu);
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return 0;
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errout:
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kfree(new);
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return err;
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}
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static void cls_cgroup_destroy(struct tcf_proto *tp)
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{
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struct cls_cgroup_head *head = rtnl_dereference(tp->root);
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if (head) {
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RCU_INIT_POINTER(tp->root, NULL);
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call_rcu(&head->rcu, cls_cgroup_destroy_rcu);
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}
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}
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static int cls_cgroup_delete(struct tcf_proto *tp, unsigned long arg)
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{
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return -EOPNOTSUPP;
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}
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static void cls_cgroup_walk(struct tcf_proto *tp, struct tcf_walker *arg)
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{
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struct cls_cgroup_head *head = rtnl_dereference(tp->root);
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if (arg->count < arg->skip)
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goto skip;
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if (arg->fn(tp, (unsigned long) head, arg) < 0) {
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arg->stop = 1;
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return;
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}
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skip:
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arg->count++;
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}
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static int cls_cgroup_dump(struct net *net, struct tcf_proto *tp, unsigned long fh,
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struct sk_buff *skb, struct tcmsg *t)
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{
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struct cls_cgroup_head *head = rtnl_dereference(tp->root);
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unsigned char *b = skb_tail_pointer(skb);
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struct nlattr *nest;
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t->tcm_handle = head->handle;
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nest = nla_nest_start(skb, TCA_OPTIONS);
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if (nest == NULL)
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goto nla_put_failure;
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if (tcf_exts_dump(skb, &head->exts) < 0 ||
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tcf_em_tree_dump(skb, &head->ematches, TCA_CGROUP_EMATCHES) < 0)
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goto nla_put_failure;
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nla_nest_end(skb, nest);
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if (tcf_exts_dump_stats(skb, &head->exts) < 0)
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goto nla_put_failure;
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return skb->len;
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nla_put_failure:
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nlmsg_trim(skb, b);
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return -1;
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}
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static struct tcf_proto_ops cls_cgroup_ops __read_mostly = {
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.kind = "cgroup",
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.init = cls_cgroup_init,
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.change = cls_cgroup_change,
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.classify = cls_cgroup_classify,
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.destroy = cls_cgroup_destroy,
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.get = cls_cgroup_get,
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.put = cls_cgroup_put,
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.delete = cls_cgroup_delete,
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.walk = cls_cgroup_walk,
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.dump = cls_cgroup_dump,
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.owner = THIS_MODULE,
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};
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static int __init init_cgroup_cls(void)
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{
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return register_tcf_proto_ops(&cls_cgroup_ops);
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}
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static void __exit exit_cgroup_cls(void)
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{
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unregister_tcf_proto_ops(&cls_cgroup_ops);
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}
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module_init(init_cgroup_cls);
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module_exit(exit_cgroup_cls);
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MODULE_LICENSE("GPL");
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