net:rfs: adjust table size checking

Make sure root user does not try something stupid.

Also make sure mask field in struct rps_sock_flow_table
does not share a cache line with the potentially often dirtied
flow table.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Fixes: 567e4b79731c ("net: rfs: add hash collision detection")
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 3 insertions, 2 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index ab3b7cef4638..d115256ed5a2 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -653,7 +653,8 @@ struct rps_dev_flow_table {
  */
 struct rps_sock_flow_table {
         u32     mask;
-        u32     ents[0];
+
+        u32     ents[0] ____cacheline_aligned_in_smp;
 };
 #define RPS_SOCK_FLOW_TABLE_SIZE(_num) (offsetof(struct rps_sock_flow_table, ents[_num]))
 
diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index 7a31be5e361f..eaa51ddf2368 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -52,7 +52,7 @@ static int rps_sock_flow_sysctl(struct ctl_table *table, int write,
 
         if (write) {
                 if (size) {
-                        if (size > 1<<30) {
+                        if (size > 1<<29) {
                                 /* Enforce limit to prevent overflow */
                                 mutex_unlock(&sock_flow_mutex);
                                 return -EINVAL;