sysctl: sysctl_binary.c Fix compilation when !CONFIG_NET

dev_get_by_index does not exist when the network stack is not
compiled in, so only include the code to follow wild card paths
when the network stack is present.

I have shuffled the code around a little to make it clear
that dev_put is called after dev_get_by_index showing that
there is no leak.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

1 files changed, 20 insertions, 15 deletions

diff --git a/kernel/sysctl_binary.c b/kernel/sysctl_binary.c
index bf0a4b06782..0cf60400542 100644
--- a/kernel/sysctl_binary.c
+++ b/kernel/sysctl_binary.c
@@ -12,6 +12,7 @@
 #include <linux/pid_namespace.h>
 #include <linux/file.h>
 #include <linux/ctype.h>
+#include <linux/netdevice.h>
 
 #ifdef CONFIG_SYSCTL_SYSCALL
 
@@ -1250,9 +1251,12 @@ out:
 static const struct bin_table *get_sysctl(const int *name, int nlen, char *path)
 {
         const struct bin_table *table = &bin_root_table[0];
-        struct net *net = current->nsproxy->net_ns;
         int ctl_name;
 
+        /* The binary sysctl tables have a small maximum depth so
+         * there is no danger of overflowing our path as it PATH_MAX
+         * bytes long.
+         */
         memcpy(path, "sys/", 4);
         path += 4;
 
@@ -1263,30 +1267,31 @@ repeat:
         name++;
         nlen--;
         for ( ; table->convert; table++) {
-                struct net_device *dev = NULL;
-                const char *procname = NULL;
+                int len = 0;
 
                 /* Use the well known sysctl number to proc name mapping */
-                if (ctl_name == table->ctl_name)
-                        procname = table->procname;
-
+                if (ctl_name == table->ctl_name) {
+                        len = strlen(table->procname);
+                        memcpy(path, table->procname, len);
+                }
+#ifdef CONFIG_NET
                 /*
                  * For a wild card entry map from ifindex to network
                  * device name.
                  */
                 else if (!table->ctl_name) {
+                        struct net *net = current->nsproxy->net_ns;
+                        struct net_device *dev;
                         dev = dev_get_by_index(net, ctl_name);
-                        if (dev)
-                                procname = dev->name;
+                        if (dev) {
+                                len = strlen(dev->name);
+                                memcpy(path, dev->name, len);
+                                dev_put(dev);
+                        }
                 }
-                if (procname) {
-                        int len;
-
-                        len = strlen(procname);
-                        memcpy(path, procname, len);
+#endif
+                if (len) {
                         path += len;
-                        if (dev)
-                                dev_put(dev);
                         if (table->child) {
                                 *path++ = '/';
                                 table = table->child;