net: don't unnecessarily load kernel modules in dev_ioctl()

Starting with v4.16-rc1 we've been seeing a higher than usual number
of requests for the kernel to load networking modules, even on events
which shouldn't trigger a module load (e.g. ioctl(TCGETS)).  Stephen
Smalley suggested the problem may lie in commit 44c02a2c3dc5
("dev_ioctl(): move copyin/copyout to callers") which moves changes
the network dev_ioctl() function to always call dev_load(),
regardless of the requested ioctl.

This patch moves the dev_load() calls back into the individual ioctls
while preserving the rest of the original patch.

Reported-by: Dominick Grift <dac.override@gmail.com>
Suggested-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 2 deletions

diff --git a/net/core/dev_ioctl.c b/net/core/dev_ioctl.c
index 0ab1af04296c..a04e1e88bf3a 100644
--- a/net/core/dev_ioctl.c
+++ b/net/core/dev_ioctl.c
@@ -402,8 +402,6 @@ int dev_ioctl(struct net *net, unsigned int cmd, struct ifreq *ifr, bool *need_c
         if (colon)
                 *colon = 0;
 
-        dev_load(net, ifr->ifr_name);
-
         /*
          *      See which interface the caller is talking about.
          */
@@ -423,6 +421,7 @@ int dev_ioctl(struct net *net, unsigned int cmd, struct ifreq *ifr, bool *need_c
         case SIOCGIFMAP:
         case SIOCGIFINDEX:
         case SIOCGIFTXQLEN:
+                dev_load(net, ifr->ifr_name);
                 rcu_read_lock();
                 ret = dev_ifsioc_locked(net, ifr, cmd);
                 rcu_read_unlock();
@@ -431,6 +430,7 @@ int dev_ioctl(struct net *net, unsigned int cmd, struct ifreq *ifr, bool *need_c
                 return ret;
 
         case SIOCETHTOOL:
+                dev_load(net, ifr->ifr_name);
                 rtnl_lock();
                 ret = dev_ethtool(net, ifr);
                 rtnl_unlock();
@@ -447,6 +447,7 @@ int dev_ioctl(struct net *net, unsigned int cmd, struct ifreq *ifr, bool *need_c
         case SIOCGMIIPHY:
         case SIOCGMIIREG:
         case SIOCSIFNAME:
+                dev_load(net, ifr->ifr_name);
                 if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
                         return -EPERM;
                 rtnl_lock();
@@ -494,6 +495,7 @@ int dev_ioctl(struct net *net, unsigned int cmd, struct ifreq *ifr, bool *need_c
                 /* fall through */
         case SIOCBONDSLAVEINFOQUERY:
         case SIOCBONDINFOQUERY:
+                dev_load(net, ifr->ifr_name);
                 rtnl_lock();
                 ret = dev_ifsioc(net, ifr, cmd);
                 rtnl_unlock();
@@ -518,6 +520,7 @@ int dev_ioctl(struct net *net, unsigned int cmd, struct ifreq *ifr, bool *need_c
                     cmd == SIOCGHWTSTAMP ||
                     (cmd >= SIOCDEVPRIVATE &&
                      cmd <= SIOCDEVPRIVATE + 15)) {
+                        dev_load(net, ifr->ifr_name);
                         rtnl_lock();
                         ret = dev_ifsioc(net, ifr, cmd);
                         rtnl_unlock();