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![Cong Wang](/assets/img/avatar_default.png)
The current implementations of ops->bind_class() are merely
searching for classid and updating class in the struct tcf_result,
without invoking either of cl_ops->bind_tcf() or
cl_ops->unbind_tcf(). This breaks the design of them as qdisc's
like cbq use them to count filters too. This is why syzbot triggered
the warning in cbq_destroy_class().
In order to fix this, we have to call cl_ops->bind_tcf() and
cl_ops->unbind_tcf() like the filter binding path. This patch does
so by refactoring out two helper functions __tcf_bind_filter()
and __tcf_unbind_filter(), which are lockless and accept a Qdisc
pointer, then teaching each implementation to call them correctly.
Note, we merely pass the Qdisc pointer as an opaque pointer to
each filter, they only need to pass it down to the helper
functions without understanding it at all.
Fixes: 07d79fc7d9
("net_sched: add reverse binding for tc class")
Reported-and-tested-by: syzbot+0a0596220218fcb603a8@syzkaller.appspotmail.com
Reported-and-tested-by: syzbot+63bdb6006961d8c917c6@syzkaller.appspotmail.com
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
354 lines
7.9 KiB
C
354 lines
7.9 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* net/sched/cls_basic.c Basic Packet Classifier.
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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/types.h>
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#include <linux/kernel.h>
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#include <linux/string.h>
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#include <linux/errno.h>
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#include <linux/rtnetlink.h>
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#include <linux/skbuff.h>
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#include <linux/idr.h>
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#include <linux/percpu.h>
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#include <net/netlink.h>
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#include <net/act_api.h>
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#include <net/pkt_cls.h>
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struct basic_head {
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struct list_head flist;
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struct idr handle_idr;
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struct rcu_head rcu;
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};
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struct basic_filter {
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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_result res;
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struct tcf_proto *tp;
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struct list_head link;
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struct tc_basic_pcnt __percpu *pf;
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struct rcu_work rwork;
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};
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static int basic_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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int r;
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struct basic_head *head = rcu_dereference_bh(tp->root);
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struct basic_filter *f;
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list_for_each_entry_rcu(f, &head->flist, link) {
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__this_cpu_inc(f->pf->rcnt);
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if (!tcf_em_tree_match(skb, &f->ematches, NULL))
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continue;
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__this_cpu_inc(f->pf->rhit);
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*res = f->res;
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r = tcf_exts_exec(skb, &f->exts, res);
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if (r < 0)
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continue;
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return r;
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}
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return -1;
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}
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static void *basic_get(struct tcf_proto *tp, u32 handle)
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{
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struct basic_head *head = rtnl_dereference(tp->root);
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struct basic_filter *f;
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list_for_each_entry(f, &head->flist, link) {
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if (f->handle == handle) {
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return f;
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}
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}
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return NULL;
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}
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static int basic_init(struct tcf_proto *tp)
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{
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struct basic_head *head;
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head = kzalloc(sizeof(*head), GFP_KERNEL);
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if (head == NULL)
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return -ENOBUFS;
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INIT_LIST_HEAD(&head->flist);
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idr_init(&head->handle_idr);
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rcu_assign_pointer(tp->root, head);
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return 0;
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}
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static void __basic_delete_filter(struct basic_filter *f)
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{
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tcf_exts_destroy(&f->exts);
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tcf_em_tree_destroy(&f->ematches);
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tcf_exts_put_net(&f->exts);
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free_percpu(f->pf);
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kfree(f);
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}
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static void basic_delete_filter_work(struct work_struct *work)
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{
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struct basic_filter *f = container_of(to_rcu_work(work),
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struct basic_filter,
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rwork);
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rtnl_lock();
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__basic_delete_filter(f);
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rtnl_unlock();
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}
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static void basic_destroy(struct tcf_proto *tp, bool rtnl_held,
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struct netlink_ext_ack *extack)
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{
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struct basic_head *head = rtnl_dereference(tp->root);
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struct basic_filter *f, *n;
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list_for_each_entry_safe(f, n, &head->flist, link) {
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list_del_rcu(&f->link);
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tcf_unbind_filter(tp, &f->res);
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idr_remove(&head->handle_idr, f->handle);
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if (tcf_exts_get_net(&f->exts))
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tcf_queue_work(&f->rwork, basic_delete_filter_work);
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else
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__basic_delete_filter(f);
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}
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idr_destroy(&head->handle_idr);
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kfree_rcu(head, rcu);
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}
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static int basic_delete(struct tcf_proto *tp, void *arg, bool *last,
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bool rtnl_held, struct netlink_ext_ack *extack)
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{
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struct basic_head *head = rtnl_dereference(tp->root);
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struct basic_filter *f = arg;
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list_del_rcu(&f->link);
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tcf_unbind_filter(tp, &f->res);
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idr_remove(&head->handle_idr, f->handle);
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tcf_exts_get_net(&f->exts);
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tcf_queue_work(&f->rwork, basic_delete_filter_work);
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*last = list_empty(&head->flist);
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return 0;
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}
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static const struct nla_policy basic_policy[TCA_BASIC_MAX + 1] = {
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[TCA_BASIC_CLASSID] = { .type = NLA_U32 },
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[TCA_BASIC_EMATCHES] = { .type = NLA_NESTED },
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};
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static int basic_set_parms(struct net *net, struct tcf_proto *tp,
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struct basic_filter *f, unsigned long base,
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struct nlattr **tb,
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struct nlattr *est, bool ovr,
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struct netlink_ext_ack *extack)
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{
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int err;
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err = tcf_exts_validate(net, tp, tb, est, &f->exts, ovr, true, extack);
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if (err < 0)
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return err;
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err = tcf_em_tree_validate(tp, tb[TCA_BASIC_EMATCHES], &f->ematches);
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if (err < 0)
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return err;
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if (tb[TCA_BASIC_CLASSID]) {
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f->res.classid = nla_get_u32(tb[TCA_BASIC_CLASSID]);
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tcf_bind_filter(tp, &f->res, base);
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}
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f->tp = tp;
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return 0;
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}
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static int basic_change(struct net *net, struct sk_buff *in_skb,
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struct tcf_proto *tp, unsigned long base, u32 handle,
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struct nlattr **tca, void **arg, bool ovr,
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bool rtnl_held, struct netlink_ext_ack *extack)
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{
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int err;
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struct basic_head *head = rtnl_dereference(tp->root);
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struct nlattr *tb[TCA_BASIC_MAX + 1];
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struct basic_filter *fold = (struct basic_filter *) *arg;
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struct basic_filter *fnew;
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if (tca[TCA_OPTIONS] == NULL)
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return -EINVAL;
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err = nla_parse_nested_deprecated(tb, TCA_BASIC_MAX, tca[TCA_OPTIONS],
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basic_policy, NULL);
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if (err < 0)
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return err;
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if (fold != NULL) {
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if (handle && fold->handle != handle)
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return -EINVAL;
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}
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fnew = kzalloc(sizeof(*fnew), GFP_KERNEL);
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if (!fnew)
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return -ENOBUFS;
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err = tcf_exts_init(&fnew->exts, net, TCA_BASIC_ACT, TCA_BASIC_POLICE);
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if (err < 0)
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goto errout;
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if (!handle) {
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handle = 1;
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err = idr_alloc_u32(&head->handle_idr, fnew, &handle,
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INT_MAX, GFP_KERNEL);
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} else if (!fold) {
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err = idr_alloc_u32(&head->handle_idr, fnew, &handle,
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handle, GFP_KERNEL);
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}
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if (err)
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goto errout;
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fnew->handle = handle;
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fnew->pf = alloc_percpu(struct tc_basic_pcnt);
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if (!fnew->pf) {
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err = -ENOMEM;
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goto errout;
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}
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err = basic_set_parms(net, tp, fnew, base, tb, tca[TCA_RATE], ovr,
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extack);
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if (err < 0) {
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if (!fold)
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idr_remove(&head->handle_idr, fnew->handle);
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goto errout;
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}
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*arg = fnew;
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if (fold) {
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idr_replace(&head->handle_idr, fnew, fnew->handle);
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list_replace_rcu(&fold->link, &fnew->link);
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tcf_unbind_filter(tp, &fold->res);
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tcf_exts_get_net(&fold->exts);
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tcf_queue_work(&fold->rwork, basic_delete_filter_work);
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} else {
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list_add_rcu(&fnew->link, &head->flist);
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}
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return 0;
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errout:
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free_percpu(fnew->pf);
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tcf_exts_destroy(&fnew->exts);
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kfree(fnew);
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return err;
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}
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static void basic_walk(struct tcf_proto *tp, struct tcf_walker *arg,
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bool rtnl_held)
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{
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struct basic_head *head = rtnl_dereference(tp->root);
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struct basic_filter *f;
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list_for_each_entry(f, &head->flist, link) {
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if (arg->count < arg->skip)
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goto skip;
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if (arg->fn(tp, f, arg) < 0) {
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arg->stop = 1;
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break;
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}
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skip:
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arg->count++;
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}
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}
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static void basic_bind_class(void *fh, u32 classid, unsigned long cl, void *q,
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unsigned long base)
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{
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struct basic_filter *f = fh;
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if (f && f->res.classid == classid) {
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if (cl)
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__tcf_bind_filter(q, &f->res, base);
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else
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__tcf_unbind_filter(q, &f->res);
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}
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}
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static int basic_dump(struct net *net, struct tcf_proto *tp, void *fh,
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struct sk_buff *skb, struct tcmsg *t, bool rtnl_held)
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{
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struct tc_basic_pcnt gpf = {};
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struct basic_filter *f = fh;
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struct nlattr *nest;
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int cpu;
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if (f == NULL)
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return skb->len;
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t->tcm_handle = f->handle;
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nest = nla_nest_start_noflag(skb, TCA_OPTIONS);
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if (nest == NULL)
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goto nla_put_failure;
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if (f->res.classid &&
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nla_put_u32(skb, TCA_BASIC_CLASSID, f->res.classid))
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goto nla_put_failure;
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for_each_possible_cpu(cpu) {
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struct tc_basic_pcnt *pf = per_cpu_ptr(f->pf, cpu);
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gpf.rcnt += pf->rcnt;
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gpf.rhit += pf->rhit;
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}
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if (nla_put_64bit(skb, TCA_BASIC_PCNT,
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sizeof(struct tc_basic_pcnt),
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&gpf, TCA_BASIC_PAD))
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goto nla_put_failure;
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if (tcf_exts_dump(skb, &f->exts) < 0 ||
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tcf_em_tree_dump(skb, &f->ematches, TCA_BASIC_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, &f->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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nla_nest_cancel(skb, nest);
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return -1;
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}
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static struct tcf_proto_ops cls_basic_ops __read_mostly = {
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.kind = "basic",
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.classify = basic_classify,
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.init = basic_init,
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.destroy = basic_destroy,
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.get = basic_get,
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.change = basic_change,
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.delete = basic_delete,
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.walk = basic_walk,
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.dump = basic_dump,
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.bind_class = basic_bind_class,
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.owner = THIS_MODULE,
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};
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static int __init init_basic(void)
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{
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return register_tcf_proto_ops(&cls_basic_ops);
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}
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static void __exit exit_basic(void)
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{
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unregister_tcf_proto_ops(&cls_basic_ops);
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}
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module_init(init_basic)
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module_exit(exit_basic)
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MODULE_LICENSE("GPL");
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