[PATCH] bridge: don't allow setting hello time to zero

Stephen Hemminger
2008-09-04T22:47:24Z

The bridge hello time can't be safely set to values less than 1 second,
otherwise it is possible to end up with a runaway timer.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>

--- a/net/bridge/br_ioctl.c 2008-09-04 15:25:41.000000000 -0700
+++ b/net/bridge/br_ioctl.c 2008-09-04 15:44:33.000000000 -0700
@@ -188,15 +188,21 @@ static int old_dev_ioctl(struct net_devi
return 0;

case BRCTL_SET_BRIDGE_HELLO_TIME:
+ {
+ unsigned long t = clock_t_to_jiffies(args[1]);
if (!capable(CAP_NET_ADMIN))
return -EPERM;

+ if (t < HZ)
+ return -EINVAL;
+
spin_lock_bh(&br->lock);
- br->bridge_hello_time = clock_t_to_jiffies(args[1]);
+ br->bridge_hello_time = t;
if (br_is_root_bridge(br))
br->hello_time = br->bridge_hello_time;
spin_unlock_bh(&br->lock);
return 0;
+ }

case BRCTL_SET_BRIDGE_MAX_AGE:
if (!capable(CAP_NET_ADMIN))
--- a/net/bridge/br_sysfs_br.c 2008-09-04 15:27:20.000000000 -0700
+++ b/net/bridge/br_sysfs_br.c 2008-09-04 15:33:31.000000000 -0700
@@ -29,11 +29,12 @@
*/
static ssize_t store_bridge_parm(struct device *d,
const char *buf, size_t len,
- void (*set)(struct net_bridge *, unsigned long))
+ int (*set)(struct net_bridge *, unsigned long))
{
struct net_bridge *br = to_bridge(d);
char *endp;
unsigned long val;
+ int err;

if (!capable(CAP_NET_ADMIN))
return -EPERM;
@@ -43,9 +44,9 @@ static ssize_t store_bridge_parm(struct
return -EINVAL;

spin_lock_bh(&br->lock);
- (*set)(br, val);
+ err = (*set)(br, val);
spin_unlock_bh(&br->lock);
- return len;
+ return err ? err : len;
}

@@ -56,12 +57,13 @@ static ssize_t show_forward_delay(struct
return sprintf(buf, "%lu\n", jiffies_to_clock_t(br->forward_delay));
}

-static void set_forward_delay(struct net_bridge *br, unsigned long val)
+static int set_forward_delay(struct net_bridge *br, unsigned long val)
{
unsigned long delay = clock_t_to_jiffies(val);
br->forward_delay = delay;
if (br_is_root_bridge(br))
br->bridge_forward_delay = delay;
+ return 0;
}

static ssize_t store_forward_delay(struct device *d,
@@ -80,12 +82,17 @@ static ssize_t show_hello_time(struct de
jiffies_to_clock_t(to_bridge(d)->hello_time));
}

-static void set_hello_time(struct net_bridge *br, unsigned long val)
+static int set_hello_time(struct net_bridge *br, unsigned long val)
{
unsigned long t = clock_t_to_jiffies(val);
+
+ if (t < HZ)
+ return -EINVAL;
+
br->hello_time = t;
if (br_is_root_bridge(br))
br->bridge_hello_time = t;
+ return 0;
}

static ssize_t store_hello_time(struct device *d,
@@ -104,12 +111,13 @@ static ssize_t show_max_age(struct devic
jiffies_to_clock_t(to_bridge(d)->max_age));
}

-static void set_max_age(struct net_bridge *br, unsigned long val)
+static int set_max_age(struct net_bridge *br, unsigned long val)
{
unsigned long t = clock_t_to_jiffies(val);
br->max_age = t;
if (br_is_root_bridge(br))
br->bridge_max_age = t;
+ return 0;
}

static ssize_t store_max_age(struct device *d, struct device_attribute *attr,
@@ -126,9 +134,10 @@ static ssize_t show_ageing_time(struct d
return sprintf(buf, "%lu\n", jiffies_to_clock_t(br->ageing_time));
}

-static void set_ageing_time(struct net_bridge *br, unsigned long val)
+static int set_ageing_time(struct net_bridge *br, unsigned long val)
{
br->ageing_time = clock_t_to_jiffies(val);
+ return 0;
}

static ssize_t store_ageing_time(struct device *d,
@@ -180,9 +189,10 @@ static ssize_t show_priority(struct devi
(br->bridge_id.prio[0] << 8) | br->bridge_id.prio[1]);
}

-static void set_priority(struct net_bridge *br, unsigned long val)
+static int set_priority(struct net_bridge *br, unsigned long val)
{
br_stp_set_bridge_priority(br, (u16) val);
+ return 0;
}

static ssize_t store_priority(struct device *d, struct device_attribute *attr,