summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
-rw-r--r--Documentation/networking/ip-sysctl.rst4
-rw-r--r--net/ipv4/icmp.c7
2 files changed, 8 insertions, 3 deletions
diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
index 837d51f9e1fa..25e6673a085a 100644
--- a/Documentation/networking/ip-sysctl.rst
+++ b/Documentation/networking/ip-sysctl.rst
@@ -1142,13 +1142,15 @@ icmp_ratelimit - INTEGER
icmp_msgs_per_sec - INTEGER
Limit maximal number of ICMP packets sent per second from this host.
Only messages whose type matches icmp_ratemask (see below) are
- controlled by this limit.
+ controlled by this limit. For security reasons, the precise count
+ of messages per second is randomized.
Default: 1000
icmp_msgs_burst - INTEGER
icmp_msgs_per_sec controls number of ICMP packets sent per second,
while icmp_msgs_burst controls the burst size of these packets.
+ For security reasons, the precise burst size is randomized.
Default: 50
diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index 07f67ced962a..005faea415a4 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -239,7 +239,7 @@ 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
*/
@@ -267,7 +267,10 @@ bool icmp_global_allow(void)
}
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;
}
WRITE_ONCE(icmp_global.credit, credit);