Commit 2e24cd75 authored by Cong Wang's avatar Cong Wang Committed by David S. Miller
Browse files

net_sched: fix ops->bind_class() implementations 



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: 07d79fc7 ("net_sched: add reverse binding for tc class")
Reported-and-tested-by: default avatar <syzbot+0a0596220218fcb603a8@syzkaller.appspotmail.com>
Reported-and-tested-by: default avatar <syzbot+63bdb6006961d8c917c6@syzkaller.appspotmail.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: default avatarCong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 16b25d1a

include/net/pkt_cls.h

+19 −14
Original line number Diff line number Diff line
@@ -141,31 +141,38 @@ __cls_set_class(unsigned long *clp, unsigned long cl) 
	return xchg(clp, cl);

}



static inline unsigned long

cls_set_class(struct Qdisc *q, unsigned long *clp, unsigned long cl)

static inline void

__tcf_bind_filter(struct Qdisc *q, struct tcf_result *r, unsigned long base)

{

	unsigned long old_cl;

	unsigned long cl;



	sch_tree_lock(q);

	old_cl = __cls_set_class(clp, cl);

	sch_tree_unlock(q);

	return old_cl;

	cl = q->ops->cl_ops->bind_tcf(q, base, r->classid);

	cl = __cls_set_class(&r->class, cl);

	if (cl)

		q->ops->cl_ops->unbind_tcf(q, cl);

}



static inline void

tcf_bind_filter(struct tcf_proto *tp, struct tcf_result *r, unsigned long base)

{

	struct Qdisc *q = tp->chain->block->q;

	unsigned long cl;



	/* Check q as it is not set for shared blocks. In that case,

	 * setting class is not supported.

	 */

	if (!q)

		return;

	cl = q->ops->cl_ops->bind_tcf(q, base, r->classid);

	cl = cls_set_class(q, &r->class, cl);

	if (cl)

	sch_tree_lock(q);

	__tcf_bind_filter(q, r, base);

	sch_tree_unlock(q);

}



static inline void

__tcf_unbind_filter(struct Qdisc *q, struct tcf_result *r)

{

	unsigned long cl;



	if ((cl = __cls_set_class(&r->class, 0)) != 0)

		q->ops->cl_ops->unbind_tcf(q, cl);

}
@@ -173,12 +180,10 @@ static inline void 
tcf_unbind_filter(struct tcf_proto *tp, struct tcf_result *r)

{

	struct Qdisc *q = tp->chain->block->q;

	unsigned long cl;



	if (!q)

		return;

	if ((cl = __cls_set_class(&r->class, 0)) != 0)

		q->ops->cl_ops->unbind_tcf(q, cl);

	__tcf_unbind_filter(q, r);

}



struct tcf_exts {

include/net/sch_generic.h

+2 −1
Original line number Diff line number Diff line
@@ -318,7 +318,8 @@ struct tcf_proto_ops { 
					  void *type_data);

	void			(*hw_del)(struct tcf_proto *tp,

					  void *type_data);

	void			(*bind_class)(void *, u32, unsigned long);

	void			(*bind_class)(void *, u32, unsigned long,

					      void *, unsigned long);

	void *			(*tmplt_create)(struct net *net,

						struct tcf_chain *chain,

						struct nlattr **tca,

net/sched/cls_basic.c

+8 −3
Original line number Diff line number Diff line
@@ -263,12 +263,17 @@ skip: 
	}

}



static void basic_bind_class(void *fh, u32 classid, unsigned long cl)

static void basic_bind_class(void *fh, u32 classid, unsigned long cl, void *q,

			     unsigned long base)

{

	struct basic_filter *f = fh;



	if (f && f->res.classid == classid)

		f->res.class = cl;

	if (f && f->res.classid == classid) {

		if (cl)

			__tcf_bind_filter(q, &f->res, base);

		else

			__tcf_unbind_filter(q, &f->res);

	}

}



static int basic_dump(struct net *net, struct tcf_proto *tp, void *fh,

net/sched/cls_bpf.c

+8 −3
Original line number Diff line number Diff line
@@ -631,12 +631,17 @@ nla_put_failure: 
	return -1;

}



static void cls_bpf_bind_class(void *fh, u32 classid, unsigned long cl)

static void cls_bpf_bind_class(void *fh, u32 classid, unsigned long cl,

			       void *q, unsigned long base)

{

	struct cls_bpf_prog *prog = fh;



	if (prog && prog->res.classid == classid)

		prog->res.class = cl;

	if (prog && prog->res.classid == classid) {

		if (cl)

			__tcf_bind_filter(q, &prog->res, base);

		else

			__tcf_unbind_filter(q, &prog->res);

	}

}



static void cls_bpf_walk(struct tcf_proto *tp, struct tcf_walker *arg,

net/sched/cls_flower.c

+8 −3
Original line number Diff line number Diff line
@@ -2765,12 +2765,17 @@ nla_put_failure: 
	return -EMSGSIZE;

}



static void fl_bind_class(void *fh, u32 classid, unsigned long cl)

static void fl_bind_class(void *fh, u32 classid, unsigned long cl, void *q,

			  unsigned long base)

{

	struct cls_fl_filter *f = fh;



	if (f && f->res.classid == classid)

		f->res.class = cl;

	if (f && f->res.classid == classid) {

		if (cl)

			__tcf_bind_filter(q, &f->res, base);

		else

			__tcf_unbind_filter(q, &f->res);

	}

}



static bool fl_delete_empty(struct tcf_proto *tp)

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