Commit be4f154d authored by Herbert Xu's avatar Herbert Xu Committed by David S. Miller
Browse files

bridge: Clamp forward_delay when enabling STP 



At some point limits were added to forward_delay.  However, the
limits are only enforced when STP is enabled.  This created a
scenario where you could have a value outside the allowed range
while STP is disabled, which then stuck around even after STP
is enabled.

This patch fixes this by clamping the value when we enable STP.

I had to move the locking around a bit to ensure that there is
no window where someone could insert a value outside the range
while we're in the middle of enabling STP.

Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>

Cheers,
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 9a062013

net/bridge/br_private.h

+1 −0
Original line number Diff line number Diff line
@@ -746,6 +746,7 @@ extern struct net_bridge_port *br_get_port(struct net_bridge *br, 
extern void br_init_port(struct net_bridge_port *p);

extern void br_become_designated_port(struct net_bridge_port *p);



extern void __br_set_forward_delay(struct net_bridge *br, unsigned long t);

extern int br_set_forward_delay(struct net_bridge *br, unsigned long x);

extern int br_set_hello_time(struct net_bridge *br, unsigned long x);

extern int br_set_max_age(struct net_bridge *br, unsigned long x);

net/bridge/br_stp.c

+15 −6
Original line number Diff line number Diff line
@@ -544,18 +544,27 @@ int br_set_max_age(struct net_bridge *br, unsigned long val) 


}



void __br_set_forward_delay(struct net_bridge *br, unsigned long t)

{

	br->bridge_forward_delay = t;

	if (br_is_root_bridge(br))

		br->forward_delay = br->bridge_forward_delay;

}



int br_set_forward_delay(struct net_bridge *br, unsigned long val)

{

	unsigned long t = clock_t_to_jiffies(val);

	int err = -ERANGE;



	spin_lock_bh(&br->lock);

	if (br->stp_enabled != BR_NO_STP &&

	    (t < BR_MIN_FORWARD_DELAY || t > BR_MAX_FORWARD_DELAY))

		return -ERANGE;

		goto unlock;



	spin_lock_bh(&br->lock);

	br->bridge_forward_delay = t;

	if (br_is_root_bridge(br))

		br->forward_delay = br->bridge_forward_delay;

	__br_set_forward_delay(br, t);

	err = 0;



unlock:

	spin_unlock_bh(&br->lock);

	return 0;

	return err;

}

net/bridge/br_stp_if.c

+10 −2
Original line number Diff line number Diff line
@@ -129,6 +129,14 @@ static void br_stp_start(struct net_bridge *br) 
	char *envp[] = { NULL };



	r = call_usermodehelper(BR_STP_PROG, argv, envp, UMH_WAIT_PROC);



	spin_lock_bh(&br->lock);



	if (br->bridge_forward_delay < BR_MIN_FORWARD_DELAY)

		__br_set_forward_delay(br, BR_MIN_FORWARD_DELAY);

	else if (br->bridge_forward_delay < BR_MAX_FORWARD_DELAY)

		__br_set_forward_delay(br, BR_MAX_FORWARD_DELAY);



	if (r == 0) {

		br->stp_enabled = BR_USER_STP;

		br_debug(br, "userspace STP started\n");
@@ -137,10 +145,10 @@ static void br_stp_start(struct net_bridge *br) 
		br_debug(br, "using kernel STP\n");



		/* To start timers on any ports left in blocking */

		spin_lock_bh(&br->lock);

		br_port_state_selection(br);

		spin_unlock_bh(&br->lock);

	}



	spin_unlock_bh(&br->lock);

}



static void br_stp_stop(struct net_bridge *br)

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