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    SubjectRe: [PATCH] Use an IDR to allocate apparmor secids
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    On 05/28/2018 10:01 AM, Matthew Wilcox wrote:
    >
    > ping?
    >
    > I have this queued up in my XArray tree. If I don't hear from you before
    > -rc1, I'll be submitting it as part of the XArray conversion.
    >
    hey Mathew,

    I've pulled this into apparmor-next and done the retuning of
    AA_SECID_INVALID a follow on patch. The reworking of the api to
    return the specific error type can wait for another cycle.


    > On Tue, May 22, 2018 at 02:32:59AM -0700, 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 */
    >> + 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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