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Diffstat (limited to 'net/ipv4/icmp.c')
-rw-r--r--net/ipv4/icmp.c45
1 files changed, 34 insertions, 11 deletions
diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index a51f0dd6a49e..2c14d607a683 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -246,7 +246,7 @@ static struct {
/**
* icmp_global_allow - Are we allowed to send one more ICMP message ?
*
- * Uses a token bucket to limit our ICMP messages to sysctl_icmp_msgs_per_sec.
+ * Uses a token bucket to limit our ICMP messages to ~sysctl_icmp_msgs_per_sec.
* Returns false if we reached the limit and can not send another packet.
* Note: called with BH disabled
*/
@@ -256,10 +256,11 @@ bool icmp_global_allow(void)
bool rc = false;
/* Check if token bucket is empty and cannot be refilled
- * without taking the spinlock.
+ * without taking the spinlock. The READ_ONCE() are paired
+ * with the following WRITE_ONCE() in this same function.
*/
- if (!icmp_global.credit) {
- delta = min_t(u32, now - icmp_global.stamp, HZ);
+ if (!READ_ONCE(icmp_global.credit)) {
+ delta = min_t(u32, now - READ_ONCE(icmp_global.stamp), HZ);
if (delta < HZ / 50)
return false;
}
@@ -269,14 +270,17 @@ bool icmp_global_allow(void)
if (delta >= HZ / 50) {
incr = sysctl_icmp_msgs_per_sec * delta / HZ ;
if (incr)
- icmp_global.stamp = now;
+ WRITE_ONCE(icmp_global.stamp, now);
}
credit = min_t(u32, icmp_global.credit + incr, sysctl_icmp_msgs_burst);
if (credit) {
- credit--;
+ /* We want to use a credit of one in average, but need to randomize
+ * it for security reasons.
+ */
+ credit = max_t(int, credit - prandom_u32_max(3), 0);
rc = true;
}
- icmp_global.credit = credit;
+ WRITE_ONCE(icmp_global.credit, credit);
spin_unlock(&icmp_global.lock);
return rc;
}
@@ -429,7 +433,7 @@ static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos);
fl4.flowi4_proto = IPPROTO_ICMP;
fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev);
- security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
+ security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4));
rt = ip_route_output_key(net, &fl4);
if (IS_ERR(rt))
goto out_unlock;
@@ -457,6 +461,23 @@ static int icmp_multipath_hash_skb(const struct sk_buff *skb)
#endif
+/*
+ * The device used for looking up which routing table to use for sending an ICMP
+ * error is preferably the source whenever it is set, which should ensure the
+ * icmp error can be sent to the source host, else lookup using the routing
+ * table of the destination device, else use the main routing table (index 0).
+ */
+static struct net_device *icmp_get_route_lookup_dev(struct sk_buff *skb)
+{
+ struct net_device *route_lookup_dev = NULL;
+
+ if (skb->dev)
+ route_lookup_dev = skb->dev;
+ else if (skb_dst(skb))
+ route_lookup_dev = skb_dst(skb)->dev;
+ return route_lookup_dev;
+}
+
static struct rtable *icmp_route_lookup(struct net *net,
struct flowi4 *fl4,
struct sk_buff *skb_in,
@@ -465,6 +486,7 @@ static struct rtable *icmp_route_lookup(struct net *net,
int type, int code,
struct icmp_bxm *param)
{
+ struct net_device *route_lookup_dev;
struct rtable *rt, *rt2;
struct flowi4 fl4_dec;
int err;
@@ -479,9 +501,10 @@ static struct rtable *icmp_route_lookup(struct net *net,
fl4->flowi4_proto = IPPROTO_ICMP;
fl4->fl4_icmp_type = type;
fl4->fl4_icmp_code = code;
- fl4->flowi4_oif = l3mdev_master_ifindex(skb_in->dev);
+ route_lookup_dev = icmp_get_route_lookup_dev(skb_in);
+ fl4->flowi4_oif = l3mdev_master_ifindex(route_lookup_dev);
- security_skb_classify_flow(skb_in, flowi4_to_flowi(fl4));
+ security_skb_classify_flow(skb_in, flowi4_to_flowi_common(fl4));
rt = __ip_route_output_key_hash(net, fl4,
icmp_multipath_hash_skb(skb_in));
if (IS_ERR(rt))
@@ -504,7 +527,7 @@ static struct rtable *icmp_route_lookup(struct net *net,
if (err)
goto relookup_failed;
- if (inet_addr_type_dev_table(net, skb_in->dev,
+ if (inet_addr_type_dev_table(net, route_lookup_dev,
fl4_dec.saddr) == RTN_LOCAL) {
rt2 = __ip_route_output_key(net, &fl4_dec);
if (IS_ERR(rt2))