net: provide a per host RSS key generic infrastructure
RSS (Receive Side Scaling) typically uses Toeplitz hash and a 40 or 52 bytes
RSS key.
Some drivers use a constant (and well known key), some drivers use a random
key per port, making bonding setups hard to tune. Well known keys increase
attack surface, considering that number of queues is usually a power of two.
This patch provides infrastructure to help drivers doing the right thing.
netdev_rss_key_fill() should be used by drivers to initialize their RSS key,
even if they provide ethtool -X support to let user redefine the key later.
A new /proc/sys/net/core/netdev_rss_key file can be used to get the host
RSS key even for drivers not providing ethtool -x support, in case some
applications want to precisely setup flows to match some RX queues.
Tested:
myhost:~# cat /proc/sys/net/core/netdev_rss_key
11:63:99:bb:79:fb:a5:a7:07:45:b2:20:bf:02:42:2d:08:1a:dd:19:2b:6b:23:ac:56:28:9d:70:c3:ac:e8:16:4b:b7:c1:10:53:a4:78:41:36:40:74:b6:15:ca:27:44:aa:b3:4d:72
myhost:~# ethtool -x eth0
RX flow hash indirection table for eth0 with 8 RX ring(s):
0: 0 1 2 3 4 5 6 7
RSS hash key:
11:63:99:bb:79:fb:a5:a7:07:45:b2:20:bf:02:42:2d:08:1a:dd:19:2b:6b:23:ac:56:28:9d:70:c3:ac:e8:16:4b:b7:c1:10:53:a4:78:41
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index b0f84f5..715f51f 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -25,6 +25,7 @@
#include <linux/slab.h>
#include <linux/rtnetlink.h>
#include <linux/sched.h>
+#include <linux/net.h>
/*
* Some useful ethtool_ops methods that're device independent.
@@ -573,6 +574,16 @@
return 0;
}
+u8 netdev_rss_key[NETDEV_RSS_KEY_LEN];
+
+void netdev_rss_key_fill(void *buffer, size_t len)
+{
+ BUG_ON(len > sizeof(netdev_rss_key));
+ net_get_random_once(netdev_rss_key, sizeof(netdev_rss_key));
+ memcpy(buffer, netdev_rss_key, len);
+}
+EXPORT_SYMBOL(netdev_rss_key_fill);
+
static noinline_for_stack int ethtool_get_rxfh_indir(struct net_device *dev,
void __user *useraddr)
{
diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index f93f092..31baba2 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -217,6 +217,18 @@
}
#endif
+static int proc_do_rss_key(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+ struct ctl_table fake_table;
+ char buf[NETDEV_RSS_KEY_LEN * 3];
+
+ snprintf(buf, sizeof(buf), "%*phC", NETDEV_RSS_KEY_LEN, netdev_rss_key);
+ fake_table.data = buf;
+ fake_table.maxlen = sizeof(buf);
+ return proc_dostring(&fake_table, write, buffer, lenp, ppos);
+}
+
static struct ctl_table net_core_table[] = {
#ifdef CONFIG_NET
{
@@ -265,6 +277,13 @@
.mode = 0644,
.proc_handler = proc_dointvec
},
+ {
+ .procname = "netdev_rss_key",
+ .data = &netdev_rss_key,
+ .maxlen = sizeof(int),
+ .mode = 0444,
+ .proc_handler = proc_do_rss_key,
+ },
#ifdef CONFIG_BPF_JIT
{
.procname = "bpf_jit_enable",