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apparmor: Use an IDR to allocate apparmor secids

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

Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>
This commit is contained in:
Matthew Wilcox 2018-05-22 02:32:59 -07:00 committed by John Johansen
parent 52e8c38001
commit 99cc45e486
1 changed files with 11 additions and 103 deletions
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114
security/apparmor/secid.c
View File

@ -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 {
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;
}
spin_unlock_irqrestore(&secid_lock, flags);
}
idr_preload(gfp);
spin_lock_irqsave(&secid_lock, flags);
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);
}