Commit 99cc45e4 authored by Matthew Wilcox's avatar Matthew Wilcox Committed by John Johansen
Browse files

apparmor: Use an IDR to allocate apparmor secids 



Replace the custom usage of the radix tree to store a list of free IDs
with the IDR.

Signed-off-by: default avatarMatthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: default avatarJohn Johansen <john.johansen@canonical.com>
parent 52e8c380

security/apparmor/secid.c

+11 −103
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ 
#include <linux/errno.h>

#include <linux/err.h>

#include <linux/gfp.h>

#include <linux/idr.h>

#include <linux/slab.h>

#include <linux/spinlock.h>
@@ -30,18 +31,10 @@ 
/*

 * secids - do not pin labels with a refcount. They rely on the label

 * properly updating/freeing them

 *

 * A singly linked free list is used to track secids that have been

 * freed and reuse them before allocating new ones

 */



#define FREE_LIST_HEAD 1



static RADIX_TREE(aa_secids_map, GFP_ATOMIC);

static DEFINE_IDR(aa_secids);

static DEFINE_SPINLOCK(secid_lock);

static u32 alloced_secid = FREE_LIST_HEAD;

static u32 free_list = FREE_LIST_HEAD;

static unsigned long free_count;



/*

 * TODO: allow policy to reserve a secid range?
@@ -49,65 +42,6 @@ static unsigned long free_count; 
 * TODO: use secid_update in label replace

 */



#define SECID_MAX U32_MAX



/* TODO: mark free list as exceptional */

static void *to_ptr(u32 secid)

{

	return (void *)

		((((unsigned long) secid) << RADIX_TREE_EXCEPTIONAL_SHIFT));

}



static u32 to_secid(void *ptr)

{

	return (u32) (((unsigned long) ptr) >> RADIX_TREE_EXCEPTIONAL_SHIFT);

}





/* TODO: tag free_list entries to mark them as different */

static u32 __pop(struct aa_label *label)

{

	u32 secid = free_list;

	void __rcu **slot;

	void *entry;



	if (free_list == FREE_LIST_HEAD)

		return AA_SECID_INVALID;



	slot = radix_tree_lookup_slot(&aa_secids_map, secid);

	AA_BUG(!slot);

	entry = radix_tree_deref_slot_protected(slot, &secid_lock);

	free_list = to_secid(entry);

	radix_tree_replace_slot(&aa_secids_map, slot, label);

	free_count--;



	return secid;

}



static void __push(u32 secid)

{

	void __rcu **slot;



	slot = radix_tree_lookup_slot(&aa_secids_map, secid);

	AA_BUG(!slot);

	radix_tree_replace_slot(&aa_secids_map, slot, to_ptr(free_list));

	free_list = secid;

	free_count++;

}



static struct aa_label * __secid_update(u32 secid, struct aa_label *label)

{

	struct aa_label *old;

	void __rcu **slot;



	slot = radix_tree_lookup_slot(&aa_secids_map, secid);

	AA_BUG(!slot);

	old = radix_tree_deref_slot_protected(slot, &secid_lock);

	radix_tree_replace_slot(&aa_secids_map, slot, label);



	return old;

}



/**

 * aa_secid_update - update a secid mapping to a new label

 * @secid: secid to update
@@ -115,11 +49,10 @@ static struct aa_label * __secid_update(u32 secid, struct aa_label *label) 
 */

void aa_secid_update(u32 secid, struct aa_label *label)

{

	struct aa_label *old;

	unsigned long flags;



	spin_lock_irqsave(&secid_lock, flags);

	old = __secid_update(secid, label);

	idr_replace(&aa_secids, label, secid);

	spin_unlock_irqrestore(&secid_lock, flags);

}
@@ -132,7 +65,7 @@ struct aa_label *aa_secid_to_label(u32 secid) 
	struct aa_label *label;



	rcu_read_lock();

	label = radix_tree_lookup(&aa_secids_map, secid);

	label = idr_find(&aa_secids, secid);

	rcu_read_unlock();



	return label;
@@ -167,7 +100,6 @@ int apparmor_secid_to_secctx(u32 secid, char **secdata, u32 *seclen) 
	return 0;

}





int apparmor_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid)

{

	struct aa_label *label;
@@ -186,7 +118,6 @@ void apparmor_release_secctx(char *secdata, u32 seclen) 
	kfree(secdata);

}





/**

 * aa_alloc_secid - allocate a new secid for a profile

 */
@@ -195,35 +126,12 @@ u32 aa_alloc_secid(struct aa_label *label, gfp_t gfp) 
	unsigned long flags;

	u32 secid;



	/* racey, but at worst causes new allocation instead of reuse */

	if (free_list == FREE_LIST_HEAD) {

		bool preload = 0;

		int res;



retry:

		if (gfpflags_allow_blocking(gfp) && !radix_tree_preload(gfp))

			preload = 1;

		spin_lock_irqsave(&secid_lock, flags);

		if (alloced_secid != SECID_MAX) {

			secid = ++alloced_secid;

			res = radix_tree_insert(&aa_secids_map, secid, label);

			AA_BUG(res == -EEXIST);

		} else {

			secid = AA_SECID_INVALID;

		}

		spin_unlock_irqrestore(&secid_lock, flags);

		if (preload)

			radix_tree_preload_end();

	} else {

	idr_preload(gfp);

	spin_lock_irqsave(&secid_lock, flags);

		/* remove entry from free list */

		secid = __pop(label);

		if (secid == AA_SECID_INVALID) {

			spin_unlock_irqrestore(&secid_lock, flags);

			goto retry;

		}

	secid = idr_alloc(&aa_secids, label, 0, 0, GFP_ATOMIC);

	/* XXX: Can return -ENOMEM */

	spin_unlock_irqrestore(&secid_lock, flags);

	}

	idr_preload_end();



	return secid;

}
@@ -237,6 +145,6 @@ void aa_free_secid(u32 secid) 
	unsigned long flags;



	spin_lock_irqsave(&secid_lock, flags);

	__push(secid);

	idr_remove(&aa_secids, secid);

	spin_unlock_irqrestore(&secid_lock, flags);

}