randstruct: Mark various structs for randomization

This marks many critical kernel structures for randomization. These are
structures that have been targeted in the past in security exploits, or
contain functions pointers, pointers to function pointer tables, lists,
workqueues, ref-counters, credentials, permissions, or are otherwise
sensitive. This initial list was extracted from Brad Spengler/PaX Team's
code in the last public patch of grsecurity/PaX based on my understanding
of the code. Changes or omissions from the original code are mine and
don't reflect the original grsecurity/PaX code.

Left out of this list is task_struct, which requires special handling
and will be covered in a subsequent patch.

Signed-off-by: Kees Cook <keescook@chromium.org>

fs/proc/internal.h

@@ -51,7 +51,7 @@ struct proc_dir_entry {
 	spinlock_t pde_unload_lock; /* proc_fops checks and pde_users bumps */
 	u8 namelen;
 	char name[];
-};
+} __randomize_layout;
 
 union proc_op {
 	int (*proc_get_link)(struct dentry *, struct path *);
@@ -70,7 +70,7 @@ struct proc_inode {
 	struct list_head sysctl_inodes;
 	const struct proc_ns_operations *ns_ops;
 	struct inode vfs_inode;
-};
+} __randomize_layout;
 
 /*
  * General functions
@@ -279,7 +279,7 @@ struct proc_maps_private {
 #ifdef CONFIG_NUMA
 	struct mempolicy *task_mempolicy;
 #endif
-};
+} __randomize_layout;
 
 struct mm_struct *proc_mem_open(struct inode *inode, unsigned int mode);