On Mon, Jun 04, 2018 at 06:27:09PM -0700, John Johansen wrote: > 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.
Oh ... here's what I currently have. I decided that AA_SECID_INVALID wasn't needed. >From 4e43853a7d984d7b16fd68f356aef1b686a05298 Mon Sep 17 00:00:00 2001 From: Matthew Wilcox <mawil...@microsoft.com> Date: Tue, 22 May 2018 05:37:19 -0400 Subject: [PATCH] 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. Change the aa_alloc_secid() API to store the secid in the label while holding the spinlock to ensure that a simultaneous lookup cannot find an uninitialised secid. Signed-off-by: Matthew Wilcox <mawil...@microsoft.com> --- security/apparmor/include/secid.h | 5 +- security/apparmor/label.c | 3 +- security/apparmor/secid.c | 135 ++++++------------------------ 3 files changed, 28 insertions(+), 115 deletions(-) diff --git a/security/apparmor/include/secid.h b/security/apparmor/include/secid.h index 686de8e50a79..a8ba767b2d2c 100644 --- a/security/apparmor/include/secid.h +++ b/security/apparmor/include/secid.h @@ -19,16 +19,13 @@ struct aa_label; -/* secid value that will not be allocated */ -#define AA_SECID_INVALID 0 - struct aa_label *aa_secid_to_label(u32 secid); int apparmor_secid_to_secctx(u32 secid, char **secdata, u32 *seclen); int apparmor_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid); void apparmor_release_secctx(char *secdata, u32 seclen); -u32 aa_alloc_secid(struct aa_label *label, gfp_t gfp); +int aa_alloc_secid(struct aa_label *label, gfp_t gfp); void aa_free_secid(u32 secid); void aa_secid_update(u32 secid, struct aa_label *label); diff --git a/security/apparmor/label.c b/security/apparmor/label.c index a17574df611b..ba11bdf9043a 100644 --- a/security/apparmor/label.c +++ b/security/apparmor/label.c @@ -407,8 +407,7 @@ bool aa_label_init(struct aa_label *label, int size, gfp_t gfp) AA_BUG(!label); AA_BUG(size < 1); - label->secid = aa_alloc_secid(label, gfp); - if (label->secid == AA_SECID_INVALID) + if (aa_alloc_secid(label, gfp) < 0) return false; label->size = size; /* doesn't include null */ diff --git a/security/apparmor/secid.c b/security/apparmor/secid.c index c2f0c1571156..bc9f8e101b65 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; @@ -186,46 +118,31 @@ void apparmor_release_secctx(char *secdata, u32 seclen) kfree(secdata); } - /** - * aa_alloc_secid - allocate a new secid for a profile + * aa_alloc_secid - Allocate a new secid for a profile. + * @label: Freshly allocated label. + * @gfp: Memory allocation flags. + * + * Initialises the label's secid with an unused ID. + * + * Context: Any context. + * Return: 0 if the label's secid has been successfully initialised. If + * memory allocation failed, returns -ENOMEM. If no more IDs are + * available, returns -ENOSPC. */ -u32 aa_alloc_secid(struct aa_label *label, gfp_t gfp) +int 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); - } - - return secid; + int err; + + idr_preload(gfp); + spin_lock_irqsave(&secid_lock, flags); + err = idr_alloc_u32(&aa_secids, label, &label->secid, UINT_MAX, + GFP_ATOMIC); + spin_unlock_irqrestore(&secid_lock, flags); + idr_preload_end(); + + return err; } /** @@ -237,6 +154,6 @@ 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); } -- 2.17.0