Messages in this thread | | | Subject | Re: [PATCH] Use an IDR to allocate apparmor secids | From | John Johansen <> | Date | Wed, 30 May 2018 16:06:42 -0700 |
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On 05/22/2018 02:32 AM, Matthew Wilcox wrote: > 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> > > security/apparmor/secid.c | 114 ++++------------------------------------------ > 1 file changed, 11 insertions(+), 103 deletions(-) > > diff --git a/security/apparmor/secid.c b/security/apparmor/secid.c > index c2f0c1571156..3ad94b2ffbb2 100644 > --- a/security/apparmor/secid.c > +++ b/security/apparmor/secid.c > @@ -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 */
need to return AA_SECID_INVALID in the event of an error
if we want to track which error we could change the api of aa_alloc_secid
> + 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); > } >
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