Merge tag 'block-5.11-2021-01-16' of git://git.kernel.dk/linux-block

[linux/fpc-iii.git] / security / apparmor / label.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * AppArmor security module
 *
 * This file contains AppArmor label definitions
 *
 * Copyright 2017 Canonical Ltd.
 */

#include <linux/audit.h>
#include <linux/seq_file.h>
#include <linux/sort.h>

#include "include/apparmor.h"
#include "include/cred.h"
#include "include/label.h"
#include "include/policy.h"
#include "include/secid.h"


/*
 * the aa_label represents the set of profiles confining an object
 *
 * Labels maintain a reference count to the set of pointers they reference
 * Labels are ref counted by
 *   tasks and object via the security field/security context off the field
 *   code - will take a ref count on a label if it needs the label
 *          beyond what is possible with an rcu_read_lock.
 *   profiles - each profile is a label
 *   secids - a pinned secid will keep a refcount of the label it is
 *          referencing
 *   objects - inode, files, sockets, ...
 *
 * Labels are not ref counted by the label set, so they maybe removed and
 * freed when no longer in use.
 *
 */

#define PROXY_POISON 97
#define LABEL_POISON 100

static void free_proxy(struct aa_proxy *proxy)
{
        if (proxy) {
                /* p->label will not updated any more as p is dead */
                aa_put_label(rcu_dereference_protected(proxy->label, true));
                memset(proxy, 0, sizeof(*proxy));
                RCU_INIT_POINTER(proxy->label, (struct aa_label *)PROXY_POISON);
                kfree(proxy);
        }
}

void aa_proxy_kref(struct kref *kref)
{
        struct aa_proxy *proxy = container_of(kref, struct aa_proxy, count);

        free_proxy(proxy);
}

struct aa_proxy *aa_alloc_proxy(struct aa_label *label, gfp_t gfp)
{
        struct aa_proxy *new;

        new = kzalloc(sizeof(struct aa_proxy), gfp);
        if (new) {
                kref_init(&new->count);
                rcu_assign_pointer(new->label, aa_get_label(label));
        }
        return new;
}

/* requires profile list write lock held */
void __aa_proxy_redirect(struct aa_label *orig, struct aa_label *new)
{
        struct aa_label *tmp;

        AA_BUG(!orig);
        AA_BUG(!new);
        lockdep_assert_held_write(&labels_set(orig)->lock);

        tmp = rcu_dereference_protected(orig->proxy->label,
                                        &labels_ns(orig)->lock);
        rcu_assign_pointer(orig->proxy->label, aa_get_label(new));
        orig->flags |= FLAG_STALE;
        aa_put_label(tmp);
}

static void __proxy_share(struct aa_label *old, struct aa_label *new)
{
        struct aa_proxy *proxy = new->proxy;

        new->proxy = aa_get_proxy(old->proxy);
        __aa_proxy_redirect(old, new);
        aa_put_proxy(proxy);
}


/**
 * ns_cmp - compare ns for label set ordering
 * @a: ns to compare (NOT NULL)
 * @b: ns to compare (NOT NULL)
 *
 * Returns: <0 if a < b
 *          ==0 if a == b
 *          >0  if a > b
 */
static int ns_cmp(struct aa_ns *a, struct aa_ns *b)
{
        int res;

        AA_BUG(!a);
        AA_BUG(!b);
        AA_BUG(!a->base.hname);
        AA_BUG(!b->base.hname);

        if (a == b)
                return 0;

        res = a->level - b->level;
        if (res)
                return res;

        return strcmp(a->base.hname, b->base.hname);
}

/**
 * profile_cmp - profile comparison for set ordering
 * @a: profile to compare (NOT NULL)
 * @b: profile to compare (NOT NULL)
 *
 * Returns: <0  if a < b
 *          ==0 if a == b
 *          >0  if a > b
 */
static int profile_cmp(struct aa_profile *a, struct aa_profile *b)
{
        int res;

        AA_BUG(!a);
        AA_BUG(!b);
        AA_BUG(!a->ns);
        AA_BUG(!b->ns);
        AA_BUG(!a->base.hname);
        AA_BUG(!b->base.hname);

        if (a == b || a->base.hname == b->base.hname)
                return 0;
        res = ns_cmp(a->ns, b->ns);
        if (res)
                return res;

        return strcmp(a->base.hname, b->base.hname);
}

/**
 * vec_cmp - label comparison for set ordering
 * @a: label to compare (NOT NULL)
 * @vec: vector of profiles to compare (NOT NULL)
 * @n: length of @vec
 *
 * Returns: <0  if a < vec
 *          ==0 if a == vec
 *          >0  if a > vec
 */
static int vec_cmp(struct aa_profile **a, int an, struct aa_profile **b, int bn)
{
        int i;

        AA_BUG(!a);
        AA_BUG(!*a);
        AA_BUG(!b);
        AA_BUG(!*b);
        AA_BUG(an <= 0);
        AA_BUG(bn <= 0);

        for (i = 0; i < an && i < bn; i++) {
                int res = profile_cmp(a[i], b[i]);

                if (res != 0)
                        return res;
        }

        return an - bn;
}

static bool vec_is_stale(struct aa_profile **vec, int n)
{
        int i;

        AA_BUG(!vec);

        for (i = 0; i < n; i++) {
                if (profile_is_stale(vec[i]))
                        return true;
        }

        return false;
}

static bool vec_unconfined(struct aa_profile **vec, int n)
{
        int i;

        AA_BUG(!vec);

        for (i = 0; i < n; i++) {
                if (!profile_unconfined(vec[i]))
                        return false;
        }

        return true;
}

static int sort_cmp(const void *a, const void *b)
{
        return profile_cmp(*(struct aa_profile **)a, *(struct aa_profile **)b);
}

/*
 * assumes vec is sorted
 * Assumes @vec has null terminator at vec[n], and will null terminate
 * vec[n - dups]
 */
static inline int unique(struct aa_profile **vec, int n)
{
        int i, pos, dups = 0;

        AA_BUG(n < 1);
        AA_BUG(!vec);

        pos = 0;
        for (i = 1; i < n; i++) {
                int res = profile_cmp(vec[pos], vec[i]);

                AA_BUG(res > 0, "vec not sorted");
                if (res == 0) {
                        /* drop duplicate */
                        aa_put_profile(vec[i]);
                        dups++;
                        continue;
                }
                pos++;
                if (dups)
                        vec[pos] = vec[i];
        }

        AA_BUG(dups < 0);

        return dups;
}

/**
 * aa_vec_unique - canonical sort and unique a list of profiles
 * @n: number of refcounted profiles in the list (@n > 0)
 * @vec: list of profiles to sort and merge
 *
 * Returns: the number of duplicates eliminated == references put
 *
 * If @flags & VEC_FLAG_TERMINATE @vec has null terminator at vec[n], and will
 * null terminate vec[n - dups]
 */
int aa_vec_unique(struct aa_profile **vec, int n, int flags)
{
        int i, dups = 0;

        AA_BUG(n < 1);
        AA_BUG(!vec);

        /* vecs are usually small and inorder, have a fallback for larger */
        if (n > 8) {
                sort(vec, n, sizeof(struct aa_profile *), sort_cmp, NULL);
                dups = unique(vec, n);
                goto out;
        }

        /* insertion sort + unique in one */
        for (i = 1; i < n; i++) {
                struct aa_profile *tmp = vec[i];
                int pos, j;

                for (pos = i - 1 - dups; pos >= 0; pos--) {
                        int res = profile_cmp(vec[pos], tmp);

                        if (res == 0) {
                                /* drop duplicate entry */
                                aa_put_profile(tmp);
                                dups++;
                                goto continue_outer;
                        } else if (res < 0)
                                break;
                }
                /* pos is at entry < tmp, or index -1. Set to insert pos */
                pos++;

                for (j = i - dups; j > pos; j--)
                        vec[j] = vec[j - 1];
                vec[pos] = tmp;
continue_outer:
                ;
        }

        AA_BUG(dups < 0);

out:
        if (flags & VEC_FLAG_TERMINATE)
                vec[n - dups] = NULL;

        return dups;
}


void aa_label_destroy(struct aa_label *label)
{
        AA_BUG(!label);

        if (!label_isprofile(label)) {
                struct aa_profile *profile;
                struct label_it i;

                aa_put_str(label->hname);

                label_for_each(i, label, profile) {
                        aa_put_profile(profile);
                        label->vec[i.i] = (struct aa_profile *)
                                           (LABEL_POISON + (long) i.i);
                }
        }

        if (label->proxy) {
                if (rcu_dereference_protected(label->proxy->label, true) == label)
                        rcu_assign_pointer(label->proxy->label, NULL);
                aa_put_proxy(label->proxy);
        }
        aa_free_secid(label->secid);

        label->proxy = (struct aa_proxy *) PROXY_POISON + 1;
}

void aa_label_free(struct aa_label *label)
{
        if (!label)
                return;

        aa_label_destroy(label);
        kfree(label);
}

static void label_free_switch(struct aa_label *label)
{
        if (label->flags & FLAG_NS_COUNT)
                aa_free_ns(labels_ns(label));
        else if (label_isprofile(label))
                aa_free_profile(labels_profile(label));
        else
                aa_label_free(label);
}

static void label_free_rcu(struct rcu_head *head)
{
        struct aa_label *label = container_of(head, struct aa_label, rcu);

        if (label->flags & FLAG_IN_TREE)
                (void) aa_label_remove(label);
        label_free_switch(label);
}

void aa_label_kref(struct kref *kref)
{
        struct aa_label *label = container_of(kref, struct aa_label, count);
        struct aa_ns *ns = labels_ns(label);

        if (!ns) {
                /* never live, no rcu callback needed, just using the fn */
                label_free_switch(label);
                return;
        }
        /* TODO: update labels_profile macro so it works here */
        AA_BUG(label_isprofile(label) &&
               on_list_rcu(&label->vec[0]->base.profiles));
        AA_BUG(label_isprofile(label) &&
               on_list_rcu(&label->vec[0]->base.list));

        /* TODO: if compound label and not stale add to reclaim cache */
        call_rcu(&label->rcu, label_free_rcu);
}

static void label_free_or_put_new(struct aa_label *label, struct aa_label *new)
{
        if (label != new)
                /* need to free directly to break circular ref with proxy */
                aa_label_free(new);
        else
                aa_put_label(new);
}

bool aa_label_init(struct aa_label *label, int size, gfp_t gfp)
{
        AA_BUG(!label);
        AA_BUG(size < 1);

        if (aa_alloc_secid(label, gfp) < 0)
                return false;

        label->size = size;                     /* doesn't include null */
        label->vec[size] = NULL;                /* null terminate */
        kref_init(&label->count);
        RB_CLEAR_NODE(&label->node);

        return true;
}

/**
 * aa_label_alloc - allocate a label with a profile vector of @size length
 * @size: size of profile vector in the label
 * @proxy: proxy to use OR null if to allocate a new one
 * @gfp: memory allocation type
 *
 * Returns: new label
 *     else NULL if failed
 */
struct aa_label *aa_label_alloc(int size, struct aa_proxy *proxy, gfp_t gfp)
{
        struct aa_label *new;

        AA_BUG(size < 1);

        /*  + 1 for null terminator entry on vec */
        new = kzalloc(sizeof(*new) + sizeof(struct aa_profile *) * (size + 1),
                        gfp);
        AA_DEBUG("%s (%p)\n", __func__, new);
        if (!new)
                goto fail;

        if (!aa_label_init(new, size, gfp))
                goto fail;

        if (!proxy) {
                proxy = aa_alloc_proxy(new, gfp);
                if (!proxy)
                        goto fail;
        } else
                aa_get_proxy(proxy);
        /* just set new's proxy, don't redirect proxy here if it was passed in*/
        new->proxy = proxy;

        return new;

fail:
        kfree(new);

        return NULL;
}


/**
 * label_cmp - label comparison for set ordering
 * @a: label to compare (NOT NULL)
 * @b: label to compare (NOT NULL)
 *
 * Returns: <0  if a < b
 *          ==0 if a == b
 *          >0  if a > b
 */
static int label_cmp(struct aa_label *a, struct aa_label *b)
{
        AA_BUG(!b);

        if (a == b)
                return 0;

        return vec_cmp(a->vec, a->size, b->vec, b->size);
}

/* helper fn for label_for_each_confined */
int aa_label_next_confined(struct aa_label *label, int i)
{
        AA_BUG(!label);
        AA_BUG(i < 0);

        for (; i < label->size; i++) {
                if (!profile_unconfined(label->vec[i]))
                        return i;
        }

        return i;
}

/**
 * aa_label_next_not_in_set - return the next profile of @sub not in @set
 * @I: label iterator
 * @set: label to test against
 * @sub: label to if is subset of @set
 *
 * Returns: profile in @sub that is not in @set, with iterator set pos after
 *     else NULL if @sub is a subset of @set
 */
struct aa_profile *__aa_label_next_not_in_set(struct label_it *I,
                                              struct aa_label *set,
                                              struct aa_label *sub)
{
        AA_BUG(!set);
        AA_BUG(!I);
        AA_BUG(I->i < 0);
        AA_BUG(I->i > set->size);
        AA_BUG(!sub);
        AA_BUG(I->j < 0);
        AA_BUG(I->j > sub->size);

        while (I->j < sub->size && I->i < set->size) {
                int res = profile_cmp(sub->vec[I->j], set->vec[I->i]);

                if (res == 0) {
                        (I->j)++;
                        (I->i)++;
                } else if (res > 0)
                        (I->i)++;
                else
                        return sub->vec[(I->j)++];
        }

        if (I->j < sub->size)
                return sub->vec[(I->j)++];

        return NULL;
}

/**
 * aa_label_is_subset - test if @sub is a subset of @set
 * @set: label to test against
 * @sub: label to test if is subset of @set
 *
 * Returns: true if @sub is subset of @set
 *     else false
 */
bool aa_label_is_subset(struct aa_label *set, struct aa_label *sub)
{
        struct label_it i = { };

        AA_BUG(!set);
        AA_BUG(!sub);

        if (sub == set)
                return true;

        return __aa_label_next_not_in_set(&i, set, sub) == NULL;
}

/**
 * aa_label_is_unconfined_subset - test if @sub is a subset of @set
 * @set: label to test against
 * @sub: label to test if is subset of @set
 *
 * This checks for subset but taking into account unconfined. IF
 * @sub contains an unconfined profile that does not have a matching
 * unconfined in @set then this will not cause the test to fail.
 * Conversely we don't care about an unconfined in @set that is not in
 * @sub
 *
 * Returns: true if @sub is special_subset of @set
 *     else false
 */
bool aa_label_is_unconfined_subset(struct aa_label *set, struct aa_label *sub)
{
        struct label_it i = { };
        struct aa_profile *p;

        AA_BUG(!set);
        AA_BUG(!sub);

        if (sub == set)
                return true;

        do {
                p = __aa_label_next_not_in_set(&i, set, sub);
                if (p && !profile_unconfined(p))
                        break;
        } while (p);

        return p == NULL;
}


/**
 * __label_remove - remove @label from the label set
 * @l: label to remove
 * @new: label to redirect to
 *
 * Requires: labels_set(@label)->lock write_lock
 * Returns:  true if the label was in the tree and removed
 */
static bool __label_remove(struct aa_label *label, struct aa_label *new)
{
        struct aa_labelset *ls = labels_set(label);

        AA_BUG(!ls);
        AA_BUG(!label);
        lockdep_assert_held_write(&ls->lock);

        if (new)
                __aa_proxy_redirect(label, new);

        if (!label_is_stale(label))
                __label_make_stale(label);

        if (label->flags & FLAG_IN_TREE) {
                rb_erase(&label->node, &ls->root);
                label->flags &= ~FLAG_IN_TREE;
                return true;
        }

        return false;
}

/**
 * __label_replace - replace @old with @new in label set
 * @old: label to remove from label set
 * @new: label to replace @old with
 *
 * Requires: labels_set(@old)->lock write_lock
 *           valid ref count be held on @new
 * Returns: true if @old was in set and replaced by @new
 *
 * Note: current implementation requires label set be order in such a way
 *       that @new directly replaces @old position in the set (ie.
 *       using pointer comparison of the label address would not work)
 */
static bool __label_replace(struct aa_label *old, struct aa_label *new)
{
        struct aa_labelset *ls = labels_set(old);

        AA_BUG(!ls);
        AA_BUG(!old);
        AA_BUG(!new);
        lockdep_assert_held_write(&ls->lock);
        AA_BUG(new->flags & FLAG_IN_TREE);

        if (!label_is_stale(old))
                __label_make_stale(old);

        if (old->flags & FLAG_IN_TREE) {
                rb_replace_node(&old->node, &new->node, &ls->root);
                old->flags &= ~FLAG_IN_TREE;
                new->flags |= FLAG_IN_TREE;
                return true;
        }

        return false;
}

/**
 * __label_insert - attempt to insert @l into a label set
 * @ls: set of labels to insert @l into (NOT NULL)
 * @label: new label to insert (NOT NULL)
 * @replace: whether insertion should replace existing entry that is not stale
 *
 * Requires: @ls->lock
 *           caller to hold a valid ref on l
 *           if @replace is true l has a preallocated proxy associated
 * Returns: @l if successful in inserting @l - with additional refcount
 *          else ref counted equivalent label that is already in the set,
 *          the else condition only happens if @replace is false
 */
static struct aa_label *__label_insert(struct aa_labelset *ls,
                                       struct aa_label *label, bool replace)
{
        struct rb_node **new, *parent = NULL;

        AA_BUG(!ls);
        AA_BUG(!label);
        AA_BUG(labels_set(label) != ls);
        lockdep_assert_held_write(&ls->lock);
        AA_BUG(label->flags & FLAG_IN_TREE);

        /* Figure out where to put new node */
        new = &ls->root.rb_node;
        while (*new) {
                struct aa_label *this = rb_entry(*new, struct aa_label, node);
                int result = label_cmp(label, this);

                parent = *new;
                if (result == 0) {
                        /* !__aa_get_label means queued for destruction,
                         * so replace in place, however the label has
                         * died before the replacement so do not share
                         * the proxy
                         */
                        if (!replace && !label_is_stale(this)) {
                                if (__aa_get_label(this))
                                        return this;
                        } else
                                __proxy_share(this, label);
                        AA_BUG(!__label_replace(this, label));
                        return aa_get_label(label);
                } else if (result < 0)
                        new = &((*new)->rb_left);
                else /* (result > 0) */
                        new = &((*new)->rb_right);
        }

        /* Add new node and rebalance tree. */
        rb_link_node(&label->node, parent, new);
        rb_insert_color(&label->node, &ls->root);
        label->flags |= FLAG_IN_TREE;

        return aa_get_label(label);
}

/**
 * __vec_find - find label that matches @vec in label set
 * @vec: vec of profiles to find matching label for (NOT NULL)
 * @n: length of @vec
 *
 * Requires: @vec_labelset(vec) lock held
 *           caller to hold a valid ref on l
 *
 * Returns: ref counted @label if matching label is in tree
 *          ref counted label that is equiv to @l in tree
 *     else NULL if @vec equiv is not in tree
 */
static struct aa_label *__vec_find(struct aa_profile **vec, int n)
{
        struct rb_node *node;

        AA_BUG(!vec);
        AA_BUG(!*vec);
        AA_BUG(n <= 0);

        node = vec_labelset(vec, n)->root.rb_node;
        while (node) {
                struct aa_label *this = rb_entry(node, struct aa_label, node);
                int result = vec_cmp(this->vec, this->size, vec, n);

                if (result > 0)
                        node = node->rb_left;
                else if (result < 0)
                        node = node->rb_right;
                else
                        return __aa_get_label(this);
        }

        return NULL;
}

/**
 * __label_find - find label @label in label set
 * @label: label to find (NOT NULL)
 *
 * Requires: labels_set(@label)->lock held
 *           caller to hold a valid ref on l
 *
 * Returns: ref counted @label if @label is in tree OR
 *          ref counted label that is equiv to @label in tree
 *     else NULL if @label or equiv is not in tree
 */
static struct aa_label *__label_find(struct aa_label *label)
{
        AA_BUG(!label);

        return __vec_find(label->vec, label->size);
}


/**
 * aa_label_remove - remove a label from the labelset
 * @label: label to remove
 *
 * Returns: true if @label was removed from the tree
 *     else @label was not in tree so it could not be removed
 */
bool aa_label_remove(struct aa_label *label)
{
        struct aa_labelset *ls = labels_set(label);
        unsigned long flags;
        bool res;

        AA_BUG(!ls);

        write_lock_irqsave(&ls->lock, flags);
        res = __label_remove(label, ns_unconfined(labels_ns(label)));
        write_unlock_irqrestore(&ls->lock, flags);

        return res;
}

/**
 * aa_label_replace - replace a label @old with a new version @new
 * @old: label to replace
 * @new: label replacing @old
 *
 * Returns: true if @old was in tree and replaced
 *     else @old was not in tree, and @new was not inserted
 */
bool aa_label_replace(struct aa_label *old, struct aa_label *new)
{
        unsigned long flags;
        bool res;

        if (name_is_shared(old, new) && labels_ns(old) == labels_ns(new)) {
                write_lock_irqsave(&labels_set(old)->lock, flags);
                if (old->proxy != new->proxy)
                        __proxy_share(old, new);
                else
                        __aa_proxy_redirect(old, new);
                res = __label_replace(old, new);
                write_unlock_irqrestore(&labels_set(old)->lock, flags);
        } else {
                struct aa_label *l;
                struct aa_labelset *ls = labels_set(old);

                write_lock_irqsave(&ls->lock, flags);
                res = __label_remove(old, new);
                if (labels_ns(old) != labels_ns(new)) {
                        write_unlock_irqrestore(&ls->lock, flags);
                        ls = labels_set(new);
                        write_lock_irqsave(&ls->lock, flags);
                }
                l = __label_insert(ls, new, true);
                res = (l == new);
                write_unlock_irqrestore(&ls->lock, flags);
                aa_put_label(l);
        }

        return res;
}

/**
 * vec_find - find label @l in label set
 * @vec: array of profiles to find equiv label for (NOT NULL)
 * @n: length of @vec
 *
 * Returns: refcounted label if @vec equiv is in tree
 *     else NULL if @vec equiv is not in tree
 */
static struct aa_label *vec_find(struct aa_profile **vec, int n)
{
        struct aa_labelset *ls;
        struct aa_label *label;
        unsigned long flags;

        AA_BUG(!vec);
        AA_BUG(!*vec);
        AA_BUG(n <= 0);

        ls = vec_labelset(vec, n);
        read_lock_irqsave(&ls->lock, flags);
        label = __vec_find(vec, n);
        read_unlock_irqrestore(&ls->lock, flags);

        return label;
}

/* requires sort and merge done first */
static struct aa_label *vec_create_and_insert_label(struct aa_profile **vec,
                                                    int len, gfp_t gfp)
{
        struct aa_label *label = NULL;
        struct aa_labelset *ls;
        unsigned long flags;
        struct aa_label *new;
        int i;

        AA_BUG(!vec);

        if (len == 1)
                return aa_get_label(&vec[0]->label);

        ls = labels_set(&vec[len - 1]->label);

        /* TODO: enable when read side is lockless
         * check if label exists before taking locks
         */
        new = aa_label_alloc(len, NULL, gfp);
        if (!new)
                return NULL;

        for (i = 0; i < len; i++)
                new->vec[i] = aa_get_profile(vec[i]);

        write_lock_irqsave(&ls->lock, flags);
        label = __label_insert(ls, new, false);
        write_unlock_irqrestore(&ls->lock, flags);
        label_free_or_put_new(label, new);

        return label;
}

struct aa_label *aa_vec_find_or_create_label(struct aa_profile **vec, int len,
                                             gfp_t gfp)
{
        struct aa_label *label = vec_find(vec, len);

        if (label)
                return label;

        return vec_create_and_insert_label(vec, len, gfp);
}

/**
 * aa_label_find - find label @label in label set
 * @label: label to find (NOT NULL)
 *
 * Requires: caller to hold a valid ref on l
 *
 * Returns: refcounted @label if @label is in tree
 *          refcounted label that is equiv to @label in tree
 *     else NULL if @label or equiv is not in tree
 */
struct aa_label *aa_label_find(struct aa_label *label)
{
        AA_BUG(!label);

        return vec_find(label->vec, label->size);
}


/**
 * aa_label_insert - insert label @label into @ls or return existing label
 * @ls - labelset to insert @label into
 * @label - label to insert
 *
 * Requires: caller to hold a valid ref on @label
 *
 * Returns: ref counted @label if successful in inserting @label
 *     else ref counted equivalent label that is already in the set
 */
struct aa_label *aa_label_insert(struct aa_labelset *ls, struct aa_label *label)
{
        struct aa_label *l;
        unsigned long flags;

        AA_BUG(!ls);
        AA_BUG(!label);

        /* check if label exists before taking lock */
        if (!label_is_stale(label)) {
                read_lock_irqsave(&ls->lock, flags);
                l = __label_find(label);
                read_unlock_irqrestore(&ls->lock, flags);
                if (l)
                        return l;
        }

        write_lock_irqsave(&ls->lock, flags);
        l = __label_insert(ls, label, false);
        write_unlock_irqrestore(&ls->lock, flags);

        return l;
}


/**
 * aa_label_next_in_merge - find the next profile when merging @a and @b
 * @I: label iterator
 * @a: label to merge
 * @b: label to merge
 *
 * Returns: next profile
 *     else null if no more profiles
 */
struct aa_profile *aa_label_next_in_merge(struct label_it *I,
                                          struct aa_label *a,
                                          struct aa_label *b)
{
        AA_BUG(!a);
        AA_BUG(!b);
        AA_BUG(!I);
        AA_BUG(I->i < 0);
        AA_BUG(I->i > a->size);
        AA_BUG(I->j < 0);
        AA_BUG(I->j > b->size);

        if (I->i < a->size) {
                if (I->j < b->size) {
                        int res = profile_cmp(a->vec[I->i], b->vec[I->j]);

                        if (res > 0)
                                return b->vec[(I->j)++];
                        if (res == 0)
                                (I->j)++;
                }

                return a->vec[(I->i)++];
        }

        if (I->j < b->size)
                return b->vec[(I->j)++];

        return NULL;
}

/**
 * label_merge_cmp - cmp of @a merging with @b against @z for set ordering
 * @a: label to merge then compare (NOT NULL)
 * @b: label to merge then compare (NOT NULL)
 * @z: label to compare merge against (NOT NULL)
 *
 * Assumes: using the most recent versions of @a, @b, and @z
 *
 * Returns: <0  if a < b
 *          ==0 if a == b
 *          >0  if a > b
 */
static int label_merge_cmp(struct aa_label *a, struct aa_label *b,
                           struct aa_label *z)
{
        struct aa_profile *p = NULL;
        struct label_it i = { };
        int k;

        AA_BUG(!a);
        AA_BUG(!b);
        AA_BUG(!z);

        for (k = 0;
             k < z->size && (p = aa_label_next_in_merge(&i, a, b));
             k++) {
                int res = profile_cmp(p, z->vec[k]);

                if (res != 0)
                        return res;
        }

        if (p)
                return 1;
        else if (k < z->size)
                return -1;
        return 0;
}

/**
 * label_merge_insert - create a new label by merging @a and @b
 * @new: preallocated label to merge into (NOT NULL)
 * @a: label to merge with @b  (NOT NULL)
 * @b: label to merge with @a  (NOT NULL)
 *
 * Requires: preallocated proxy
 *
 * Returns: ref counted label either @new if merge is unique
 *          @a if @b is a subset of @a
 *          @b if @a is a subset of @b
 *
 * NOTE: will not use @new if the merge results in @new == @a or @b
 *
 *       Must be used within labelset write lock to avoid racing with
 *       setting labels stale.
 */
static struct aa_label *label_merge_insert(struct aa_label *new,
                                           struct aa_label *a,
                                           struct aa_label *b)
{
        struct aa_label *label;
        struct aa_labelset *ls;
        struct aa_profile *next;
        struct label_it i;
        unsigned long flags;
        int k = 0, invcount = 0;
        bool stale = false;

        AA_BUG(!a);
        AA_BUG(a->size < 0);
        AA_BUG(!b);
        AA_BUG(b->size < 0);
        AA_BUG(!new);
        AA_BUG(new->size < a->size + b->size);

        label_for_each_in_merge(i, a, b, next) {
                AA_BUG(!next);
                if (profile_is_stale(next)) {
                        new->vec[k] = aa_get_newest_profile(next);
                        AA_BUG(!new->vec[k]->label.proxy);
                        AA_BUG(!new->vec[k]->label.proxy->label);
                        if (next->label.proxy != new->vec[k]->label.proxy)
                                invcount++;
                        k++;
                        stale = true;
                } else
                        new->vec[k++] = aa_get_profile(next);
        }
        /* set to actual size which is <= allocated len */
        new->size = k;
        new->vec[k] = NULL;

        if (invcount) {
                new->size -= aa_vec_unique(&new->vec[0], new->size,
                                           VEC_FLAG_TERMINATE);
                /* TODO: deal with reference labels */
                if (new->size == 1) {
                        label = aa_get_label(&new->vec[0]->label);
                        return label;
                }
        } else if (!stale) {
                /*
                 * merge could be same as a || b, note: it is not possible
                 * for new->size == a->size == b->size unless a == b
                 */
                if (k == a->size)
                        return aa_get_label(a);
                else if (k == b->size)
                        return aa_get_label(b);
        }
        if (vec_unconfined(new->vec, new->size))
                new->flags |= FLAG_UNCONFINED;
        ls = labels_set(new);
        write_lock_irqsave(&ls->lock, flags);
        label = __label_insert(labels_set(new), new, false);
        write_unlock_irqrestore(&ls->lock, flags);

        return label;
}

/**
 * labelset_of_merge - find which labelset a merged label should be inserted
 * @a: label to merge and insert
 * @b: label to merge and insert
 *
 * Returns: labelset that the merged label should be inserted into
 */
static struct aa_labelset *labelset_of_merge(struct aa_label *a,
                                             struct aa_label *b)
{
        struct aa_ns *nsa = labels_ns(a);
        struct aa_ns *nsb = labels_ns(b);

        if (ns_cmp(nsa, nsb) <= 0)
                return &nsa->labels;
        return &nsb->labels;
}

/**
 * __label_find_merge - find label that is equiv to merge of @a and @b
 * @ls: set of labels to search (NOT NULL)
 * @a: label to merge with @b  (NOT NULL)
 * @b: label to merge with @a  (NOT NULL)
 *
 * Requires: ls->lock read_lock held
 *
 * Returns: ref counted label that is equiv to merge of @a and @b
 *     else NULL if merge of @a and @b is not in set
 */
static struct aa_label *__label_find_merge(struct aa_labelset *ls,
                                           struct aa_label *a,
                                           struct aa_label *b)
{
        struct rb_node *node;

        AA_BUG(!ls);
        AA_BUG(!a);
        AA_BUG(!b);

        if (a == b)
                return __label_find(a);

        node  = ls->root.rb_node;
        while (node) {
                struct aa_label *this = container_of(node, struct aa_label,
                                                     node);
                int result = label_merge_cmp(a, b, this);

                if (result < 0)
                        node = node->rb_left;
                else if (result > 0)
                        node = node->rb_right;
                else
                        return __aa_get_label(this);
        }

        return NULL;
}


/**
 * aa_label_find_merge - find label that is equiv to merge of @a and @b
 * @a: label to merge with @b  (NOT NULL)
 * @b: label to merge with @a  (NOT NULL)
 *
 * Requires: labels be fully constructed with a valid ns
 *
 * Returns: ref counted label that is equiv to merge of @a and @b
 *     else NULL if merge of @a and @b is not in set
 */
struct aa_label *aa_label_find_merge(struct aa_label *a, struct aa_label *b)
{
        struct aa_labelset *ls;
        struct aa_label *label, *ar = NULL, *br = NULL;
        unsigned long flags;

        AA_BUG(!a);
        AA_BUG(!b);

        if (label_is_stale(a))
                a = ar = aa_get_newest_label(a);
        if (label_is_stale(b))
                b = br = aa_get_newest_label(b);
        ls = labelset_of_merge(a, b);
        read_lock_irqsave(&ls->lock, flags);
        label = __label_find_merge(ls, a, b);
        read_unlock_irqrestore(&ls->lock, flags);
        aa_put_label(ar);
        aa_put_label(br);

        return label;
}

/**
 * aa_label_merge - attempt to insert new merged label of @a and @b
 * @ls: set of labels to insert label into (NOT NULL)
 * @a: label to merge with @b  (NOT NULL)
 * @b: label to merge with @a  (NOT NULL)
 * @gfp: memory allocation type
 *
 * Requires: caller to hold valid refs on @a and @b
 *           labels be fully constructed with a valid ns
 *
 * Returns: ref counted new label if successful in inserting merge of a & b
 *     else ref counted equivalent label that is already in the set.
 *     else NULL if could not create label (-ENOMEM)
 */
struct aa_label *aa_label_merge(struct aa_label *a, struct aa_label *b,
                                gfp_t gfp)
{
        struct aa_label *label = NULL;

        AA_BUG(!a);
        AA_BUG(!b);

        if (a == b)
                return aa_get_newest_label(a);

        /* TODO: enable when read side is lockless
         * check if label exists before taking locks
        if (!label_is_stale(a) && !label_is_stale(b))
                label = aa_label_find_merge(a, b);
        */

        if (!label) {
                struct aa_label *new;

                a = aa_get_newest_label(a);
                b = aa_get_newest_label(b);

                /* could use label_merge_len(a, b), but requires double
                 * comparison for small savings
                 */
                new = aa_label_alloc(a->size + b->size, NULL, gfp);
                if (!new)
                        goto out;

                label = label_merge_insert(new, a, b);
                label_free_or_put_new(label, new);
out:
                aa_put_label(a);
                aa_put_label(b);
        }

        return label;
}

static inline bool label_is_visible(struct aa_profile *profile,
                                    struct aa_label *label)
{
        return aa_ns_visible(profile->ns, labels_ns(label), true);
}

/* match a profile and its associated ns component if needed
 * Assumes visibility test has already been done.
 * If a subns profile is not to be matched should be prescreened with
 * visibility test.
 */
static inline unsigned int match_component(struct aa_profile *profile,
                                           struct aa_profile *tp,
                                           unsigned int state)
{
        const char *ns_name;

        if (profile->ns == tp->ns)
                return aa_dfa_match(profile->policy.dfa, state, tp->base.hname);

        /* try matching with namespace name and then profile */
        ns_name = aa_ns_name(profile->ns, tp->ns, true);
        state = aa_dfa_match_len(profile->policy.dfa, state, ":", 1);
        state = aa_dfa_match(profile->policy.dfa, state, ns_name);
        state = aa_dfa_match_len(profile->policy.dfa, state, ":", 1);
        return aa_dfa_match(profile->policy.dfa, state, tp->base.hname);
}

/**
 * label_compound_match - find perms for full compound label
 * @profile: profile to find perms for
 * @label: label to check access permissions for
 * @start: state to start match in
 * @subns: whether to do permission checks on components in a subns
 * @request: permissions to request
 * @perms: perms struct to set
 *
 * Returns: 0 on success else ERROR
 *
 * For the label A//&B//&C this does the perm match for A//&B//&C
 * @perms should be preinitialized with allperms OR a previous permission
 *        check to be stacked.
 */
static int label_compound_match(struct aa_profile *profile,
                                struct aa_label *label,
                                unsigned int state, bool subns, u32 request,
                                struct aa_perms *perms)
{
        struct aa_profile *tp;
        struct label_it i;

        /* find first subcomponent that is visible */
        label_for_each(i, label, tp) {
                if (!aa_ns_visible(profile->ns, tp->ns, subns))
                        continue;
                state = match_component(profile, tp, state);
                if (!state)
                        goto fail;
                goto next;
        }

        /* no component visible */
        *perms = allperms;
        return 0;

next:
        label_for_each_cont(i, label, tp) {
                if (!aa_ns_visible(profile->ns, tp->ns, subns))
                        continue;
                state = aa_dfa_match(profile->policy.dfa, state, "//&");
                state = match_component(profile, tp, state);
                if (!state)
                        goto fail;
        }
        aa_compute_perms(profile->policy.dfa, state, perms);
        aa_apply_modes_to_perms(profile, perms);
        if ((perms->allow & request) != request)
                return -EACCES;

        return 0;

fail:
        *perms = nullperms;
        return state;
}

/**
 * label_components_match - find perms for all subcomponents of a label
 * @profile: profile to find perms for
 * @label: label to check access permissions for
 * @start: state to start match in
 * @subns: whether to do permission checks on components in a subns
 * @request: permissions to request
 * @perms: an initialized perms struct to add accumulation to
 *
 * Returns: 0 on success else ERROR
 *
 * For the label A//&B//&C this does the perm match for each of A and B and C
 * @perms should be preinitialized with allperms OR a previous permission
 *        check to be stacked.
 */
static int label_components_match(struct aa_profile *profile,
                                  struct aa_label *label, unsigned int start,
                                  bool subns, u32 request,
                                  struct aa_perms *perms)
{
        struct aa_profile *tp;
        struct label_it i;
        struct aa_perms tmp;
        unsigned int state = 0;

        /* find first subcomponent to test */
        label_for_each(i, label, tp) {
                if (!aa_ns_visible(profile->ns, tp->ns, subns))
                        continue;
                state = match_component(profile, tp, start);
                if (!state)
                        goto fail;
                goto next;
        }

        /* no subcomponents visible - no change in perms */
        return 0;

next:
        aa_compute_perms(profile->policy.dfa, state, &tmp);
        aa_apply_modes_to_perms(profile, &tmp);
        aa_perms_accum(perms, &tmp);
        label_for_each_cont(i, label, tp) {
                if (!aa_ns_visible(profile->ns, tp->ns, subns))
                        continue;
                state = match_component(profile, tp, start);
                if (!state)
                        goto fail;
                aa_compute_perms(profile->policy.dfa, state, &tmp);
                aa_apply_modes_to_perms(profile, &tmp);
                aa_perms_accum(perms, &tmp);
        }

        if ((perms->allow & request) != request)
                return -EACCES;

        return 0;

fail:
        *perms = nullperms;
        return -EACCES;
}

/**
 * aa_label_match - do a multi-component label match
 * @profile: profile to match against (NOT NULL)
 * @label: label to match (NOT NULL)
 * @state: state to start in
 * @subns: whether to match subns components
 * @request: permission request
 * @perms: Returns computed perms (NOT NULL)
 *
 * Returns: the state the match finished in, may be the none matching state
 */
int aa_label_match(struct aa_profile *profile, struct aa_label *label,
                   unsigned int state, bool subns, u32 request,
                   struct aa_perms *perms)
{
        int error = label_compound_match(profile, label, state, subns, request,
                                         perms);
        if (!error)
                return error;

        *perms = allperms;
        return label_components_match(profile, label, state, subns, request,
                                      perms);
}


/**
 * aa_update_label_name - update a label to have a stored name
 * @ns: ns being viewed from (NOT NULL)
 * @label: label to update (NOT NULL)
 * @gfp: type of memory allocation
 *
 * Requires: labels_set(label) not locked in caller
 *
 * note: only updates the label name if it does not have a name already
 *       and if it is in the labelset
 */
bool aa_update_label_name(struct aa_ns *ns, struct aa_label *label, gfp_t gfp)
{
        struct aa_labelset *ls;
        unsigned long flags;
        char __counted *name;
        bool res = false;

        AA_BUG(!ns);
        AA_BUG(!label);

        if (label->hname || labels_ns(label) != ns)
                return res;

        if (aa_label_acntsxprint(&name, ns, label, FLAGS_NONE, gfp) == -1)
                return res;

        ls = labels_set(label);
        write_lock_irqsave(&ls->lock, flags);
        if (!label->hname && label->flags & FLAG_IN_TREE) {
                label->hname = name;
                res = true;
        } else
                aa_put_str(name);
        write_unlock_irqrestore(&ls->lock, flags);

        return res;
}

/*
 * cached label name is present and visible
 * @label->hname only exists if label is namespace hierachical
 */
static inline bool use_label_hname(struct aa_ns *ns, struct aa_label *label,
                                   int flags)
{
        if (label->hname && (!ns || labels_ns(label) == ns) &&
            !(flags & ~FLAG_SHOW_MODE))
                return true;

        return false;
}

/* helper macro for snprint routines */
#define update_for_len(total, len, size, str)   \
do {                                    \
        size_t ulen = len;              \
                                        \
        AA_BUG(len < 0);                \
        total += ulen;                  \
        ulen = min(ulen, size);         \
        size -= ulen;                   \
        str += ulen;                    \
} while (0)

/**
 * aa_profile_snxprint - print a profile name to a buffer
 * @str: buffer to write to. (MAY BE NULL if @size == 0)
 * @size: size of buffer
 * @view: namespace profile is being viewed from
 * @profile: profile to view (NOT NULL)
 * @flags: whether to include the mode string
 * @prev_ns: last ns printed when used in compound print
 *
 * Returns: size of name written or would be written if larger than
 *          available buffer
 *
 * Note: will not print anything if the profile is not visible
 */
static int aa_profile_snxprint(char *str, size_t size, struct aa_ns *view,
                               struct aa_profile *profile, int flags,
                               struct aa_ns **prev_ns)
{
        const char *ns_name = NULL;

        AA_BUG(!str && size != 0);
        AA_BUG(!profile);

        if (!view)
                view = profiles_ns(profile);

        if (view != profile->ns &&
            (!prev_ns || (*prev_ns != profile->ns))) {
                if (prev_ns)
                        *prev_ns = profile->ns;
                ns_name = aa_ns_name(view, profile->ns,
                                     flags & FLAG_VIEW_SUBNS);
                if (ns_name == aa_hidden_ns_name) {
                        if (flags & FLAG_HIDDEN_UNCONFINED)
                                return snprintf(str, size, "%s", "unconfined");
                        return snprintf(str, size, "%s", ns_name);
                }
        }

        if ((flags & FLAG_SHOW_MODE) && profile != profile->ns->unconfined) {
                const char *modestr = aa_profile_mode_names[profile->mode];

                if (ns_name)
                        return snprintf(str, size, ":%s:%s (%s)", ns_name,
                                        profile->base.hname, modestr);
                return snprintf(str, size, "%s (%s)", profile->base.hname,
                                modestr);
        }

        if (ns_name)
                return snprintf(str, size, ":%s:%s", ns_name,
                                profile->base.hname);
        return snprintf(str, size, "%s", profile->base.hname);
}

static const char *label_modename(struct aa_ns *ns, struct aa_label *label,
                                  int flags)
{
        struct aa_profile *profile;
        struct label_it i;
        int mode = -1, count = 0;

        label_for_each(i, label, profile) {
                if (aa_ns_visible(ns, profile->ns, flags & FLAG_VIEW_SUBNS)) {
                        count++;
                        if (profile == profile->ns->unconfined)
                                /* special case unconfined so stacks with
                                 * unconfined don't report as mixed. ie.
                                 * profile_foo//&:ns1:unconfined (mixed)
                                 */
                                continue;
                        if (mode == -1)
                                mode = profile->mode;
                        else if (mode != profile->mode)
                                return "mixed";
                }
        }

        if (count == 0)
                return "-";
        if (mode == -1)
                /* everything was unconfined */
                mode = APPARMOR_UNCONFINED;

        return aa_profile_mode_names[mode];
}

/* if any visible label is not unconfined the display_mode returns true */
static inline bool display_mode(struct aa_ns *ns, struct aa_label *label,
                                int flags)
{
        if ((flags & FLAG_SHOW_MODE)) {
                struct aa_profile *profile;
                struct label_it i;

                label_for_each(i, label, profile) {
                        if (aa_ns_visible(ns, profile->ns,
                                          flags & FLAG_VIEW_SUBNS) &&
                            profile != profile->ns->unconfined)
                                return true;
                }
                /* only ns->unconfined in set of profiles in ns */
                return false;
        }

        return false;
}

/**
 * aa_label_snxprint - print a label name to a string buffer
 * @str: buffer to write to. (MAY BE NULL if @size == 0)
 * @size: size of buffer
 * @ns: namespace profile is being viewed from
 * @label: label to view (NOT NULL)
 * @flags: whether to include the mode string
 *
 * Returns: size of name written or would be written if larger than
 *          available buffer
 *
 * Note: labels do not have to be strictly hierarchical to the ns as
 *       objects may be shared across different namespaces and thus
 *       pickup labeling from each ns.  If a particular part of the
 *       label is not visible it will just be excluded.  And if none
 *       of the label is visible "---" will be used.
 */
int aa_label_snxprint(char *str, size_t size, struct aa_ns *ns,
                      struct aa_label *label, int flags)
{
        struct aa_profile *profile;
        struct aa_ns *prev_ns = NULL;
        struct label_it i;
        int count = 0, total = 0;
        ssize_t len;

        AA_BUG(!str && size != 0);
        AA_BUG(!label);

        if (flags & FLAG_ABS_ROOT) {
                ns = root_ns;
                len = snprintf(str, size, "=");
                update_for_len(total, len, size, str);
        } else if (!ns) {
                ns = labels_ns(label);
        }

        label_for_each(i, label, profile) {
                if (aa_ns_visible(ns, profile->ns, flags & FLAG_VIEW_SUBNS)) {
                        if (count > 0) {
                                len = snprintf(str, size, "//&");
                                update_for_len(total, len, size, str);
                        }
                        len = aa_profile_snxprint(str, size, ns, profile,
                                                  flags & FLAG_VIEW_SUBNS,
                                                  &prev_ns);
                        update_for_len(total, len, size, str);
                        count++;
                }
        }

        if (count == 0) {
                if (flags & FLAG_HIDDEN_UNCONFINED)
                        return snprintf(str, size, "%s", "unconfined");
                return snprintf(str, size, "%s", aa_hidden_ns_name);
        }

        /* count == 1 && ... is for backwards compat where the mode
         * is not displayed for 'unconfined' in the current ns
         */
        if (display_mode(ns, label, flags)) {
                len = snprintf(str, size, " (%s)",
                               label_modename(ns, label, flags));
                update_for_len(total, len, size, str);
        }

        return total;
}
#undef update_for_len

/**
 * aa_label_asxprint - allocate a string buffer and print label into it
 * @strp: Returns - the allocated buffer with the label name. (NOT NULL)
 * @ns: namespace profile is being viewed from
 * @label: label to view (NOT NULL)
 * @flags: flags controlling what label info is printed
 * @gfp: kernel memory allocation type
 *
 * Returns: size of name written or would be written if larger than
 *          available buffer
 */
int aa_label_asxprint(char **strp, struct aa_ns *ns, struct aa_label *label,
                      int flags, gfp_t gfp)
{
        int size;

        AA_BUG(!strp);
        AA_BUG(!label);

        size = aa_label_snxprint(NULL, 0, ns, label, flags);
        if (size < 0)
                return size;

        *strp = kmalloc(size + 1, gfp);
        if (!*strp)
                return -ENOMEM;
        return aa_label_snxprint(*strp, size + 1, ns, label, flags);
}

/**
 * aa_label_acntsxprint - allocate a __counted string buffer and print label
 * @strp: buffer to write to. (MAY BE NULL if @size == 0)
 * @ns: namespace profile is being viewed from
 * @label: label to view (NOT NULL)
 * @flags: flags controlling what label info is printed
 * @gfp: kernel memory allocation type
 *
 * Returns: size of name written or would be written if larger than
 *          available buffer
 */
int aa_label_acntsxprint(char __counted **strp, struct aa_ns *ns,
                         struct aa_label *label, int flags, gfp_t gfp)
{
        int size;

        AA_BUG(!strp);
        AA_BUG(!label);

        size = aa_label_snxprint(NULL, 0, ns, label, flags);
        if (size < 0)
                return size;

        *strp = aa_str_alloc(size + 1, gfp);
        if (!*strp)
                return -ENOMEM;
        return aa_label_snxprint(*strp, size + 1, ns, label, flags);
}


void aa_label_xaudit(struct audit_buffer *ab, struct aa_ns *ns,
                     struct aa_label *label, int flags, gfp_t gfp)
{
        const char *str;
        char *name = NULL;
        int len;

        AA_BUG(!ab);
        AA_BUG(!label);

        if (!use_label_hname(ns, label, flags) ||
            display_mode(ns, label, flags)) {
                len  = aa_label_asxprint(&name, ns, label, flags, gfp);
                if (len == -1) {
                        AA_DEBUG("label print error");
                        return;
                }
                str = name;
        } else {
                str = (char *) label->hname;
                len = strlen(str);
        }
        if (audit_string_contains_control(str, len))
                audit_log_n_hex(ab, str, len);
        else
                audit_log_n_string(ab, str, len);

        kfree(name);
}

void aa_label_seq_xprint(struct seq_file *f, struct aa_ns *ns,
                         struct aa_label *label, int flags, gfp_t gfp)
{
        AA_BUG(!f);
        AA_BUG(!label);

        if (!use_label_hname(ns, label, flags)) {
                char *str;
                int len;

                len = aa_label_asxprint(&str, ns, label, flags, gfp);
                if (len == -1) {
                        AA_DEBUG("label print error");
                        return;
                }
                seq_puts(f, str);
                kfree(str);
        } else if (display_mode(ns, label, flags))
                seq_printf(f, "%s (%s)", label->hname,
                           label_modename(ns, label, flags));
        else
                seq_puts(f, label->hname);
}

void aa_label_xprintk(struct aa_ns *ns, struct aa_label *label, int flags,
                      gfp_t gfp)
{
        AA_BUG(!label);

        if (!use_label_hname(ns, label, flags)) {
                char *str;
                int len;

                len = aa_label_asxprint(&str, ns, label, flags, gfp);
                if (len == -1) {
                        AA_DEBUG("label print error");
                        return;
                }
                pr_info("%s", str);
                kfree(str);
        } else if (display_mode(ns, label, flags))
                pr_info("%s (%s)", label->hname,
                       label_modename(ns, label, flags));
        else
                pr_info("%s", label->hname);
}

void aa_label_audit(struct audit_buffer *ab, struct aa_label *label, gfp_t gfp)
{
        struct aa_ns *ns = aa_get_current_ns();

        aa_label_xaudit(ab, ns, label, FLAG_VIEW_SUBNS, gfp);
        aa_put_ns(ns);
}

void aa_label_seq_print(struct seq_file *f, struct aa_label *label, gfp_t gfp)
{
        struct aa_ns *ns = aa_get_current_ns();

        aa_label_seq_xprint(f, ns, label, FLAG_VIEW_SUBNS, gfp);
        aa_put_ns(ns);
}

void aa_label_printk(struct aa_label *label, gfp_t gfp)
{
        struct aa_ns *ns = aa_get_current_ns();

        aa_label_xprintk(ns, label, FLAG_VIEW_SUBNS, gfp);
        aa_put_ns(ns);
}

static int label_count_strn_entries(const char *str, size_t n)
{
        const char *end = str + n;
        const char *split;
        int count = 1;

        AA_BUG(!str);

        for (split = aa_label_strn_split(str, end - str);
             split;
             split = aa_label_strn_split(str, end - str)) {
                count++;
                str = split + 3;
        }

        return count;
}

/*
 * ensure stacks with components like
 *   :ns:A//&B
 * have :ns: applied to both 'A' and 'B' by making the lookup relative
 * to the base if the lookup specifies an ns, else making the stacked lookup
 * relative to the last embedded ns in the string.
 */
static struct aa_profile *fqlookupn_profile(struct aa_label *base,
                                            struct aa_label *currentbase,
                                            const char *str, size_t n)
{
        const char *first = skipn_spaces(str, n);

        if (first && *first == ':')
                return aa_fqlookupn_profile(base, str, n);

        return aa_fqlookupn_profile(currentbase, str, n);
}

/**
 * aa_label_strn_parse - parse, validate and convert a text string to a label
 * @base: base label to use for lookups (NOT NULL)
 * @str: null terminated text string (NOT NULL)
 * @n: length of str to parse, will stop at \0 if encountered before n
 * @gfp: allocation type
 * @create: true if should create compound labels if they don't exist
 * @force_stack: true if should stack even if no leading &
 *
 * Returns: the matching refcounted label if present
 *     else ERRPTR
 */
struct aa_label *aa_label_strn_parse(struct aa_label *base, const char *str,
                                     size_t n, gfp_t gfp, bool create,
                                     bool force_stack)
{
        DEFINE_VEC(profile, vec);
        struct aa_label *label, *currbase = base;
        int i, len, stack = 0, error;
        const char *end = str + n;
        const char *split;

        AA_BUG(!base);
        AA_BUG(!str);

        str = skipn_spaces(str, n);
        if (str == NULL || (*str == '=' && base != &root_ns->unconfined->label))
                return ERR_PTR(-EINVAL);

        len = label_count_strn_entries(str, end - str);
        if (*str == '&' || force_stack) {
                /* stack on top of base */
                stack = base->size;
                len += stack;
                if (*str == '&')
                        str++;
        }

        error = vec_setup(profile, vec, len, gfp);
        if (error)
                return ERR_PTR(error);

        for (i = 0; i < stack; i++)
                vec[i] = aa_get_profile(base->vec[i]);

        for (split = aa_label_strn_split(str, end - str), i = stack;
             split && i < len; i++) {
                vec[i] = fqlookupn_profile(base, currbase, str, split - str);
                if (!vec[i])
                        goto fail;
                /*
                 * if component specified a new ns it becomes the new base
                 * so that subsequent lookups are relative to it
                 */
                if (vec[i]->ns != labels_ns(currbase))
                        currbase = &vec[i]->label;
                str = split + 3;
                split = aa_label_strn_split(str, end - str);
        }
        /* last element doesn't have a split */
        if (i < len) {
                vec[i] = fqlookupn_profile(base, currbase, str, end - str);
                if (!vec[i])
                        goto fail;
        }
        if (len == 1)
                /* no need to free vec as len < LOCAL_VEC_ENTRIES */
                return &vec[0]->label;

        len -= aa_vec_unique(vec, len, VEC_FLAG_TERMINATE);
        /* TODO: deal with reference labels */
        if (len == 1) {
                label = aa_get_label(&vec[0]->label);
                goto out;
        }

        if (create)
                label = aa_vec_find_or_create_label(vec, len, gfp);
        else
                label = vec_find(vec, len);
        if (!label)
                goto fail;

out:
        /* use adjusted len from after vec_unique, not original */
        vec_cleanup(profile, vec, len);
        return label;

fail:
        label = ERR_PTR(-ENOENT);
        goto out;
}

struct aa_label *aa_label_parse(struct aa_label *base, const char *str,
                                gfp_t gfp, bool create, bool force_stack)
{
        return aa_label_strn_parse(base, str, strlen(str), gfp, create,
                                   force_stack);
}

/**
 * aa_labelset_destroy - remove all labels from the label set
 * @ls: label set to cleanup (NOT NULL)
 *
 * Labels that are removed from the set may still exist beyond the set
 * being destroyed depending on their reference counting
 */
void aa_labelset_destroy(struct aa_labelset *ls)
{
        struct rb_node *node;
        unsigned long flags;

        AA_BUG(!ls);

        write_lock_irqsave(&ls->lock, flags);
        for (node = rb_first(&ls->root); node; node = rb_first(&ls->root)) {
                struct aa_label *this = rb_entry(node, struct aa_label, node);

                if (labels_ns(this) != root_ns)
                        __label_remove(this,
                                       ns_unconfined(labels_ns(this)->parent));
                else
                        __label_remove(this, NULL);
        }
        write_unlock_irqrestore(&ls->lock, flags);
}

/*
 * @ls: labelset to init (NOT NULL)
 */
void aa_labelset_init(struct aa_labelset *ls)
{
        AA_BUG(!ls);

        rwlock_init(&ls->lock);
        ls->root = RB_ROOT;
}

static struct aa_label *labelset_next_stale(struct aa_labelset *ls)
{
        struct aa_label *label;
        struct rb_node *node;
        unsigned long flags;

        AA_BUG(!ls);

        read_lock_irqsave(&ls->lock, flags);

        __labelset_for_each(ls, node) {
                label = rb_entry(node, struct aa_label, node);
                if ((label_is_stale(label) ||
                     vec_is_stale(label->vec, label->size)) &&
                    __aa_get_label(label))
                        goto out;

        }
        label = NULL;

out:
        read_unlock_irqrestore(&ls->lock, flags);

        return label;
}

/**
 * __label_update - insert updated version of @label into labelset
 * @label - the label to update/replace
 *
 * Returns: new label that is up to date
 *     else NULL on failure
 *
 * Requires: @ns lock be held
 *
 * Note: worst case is the stale @label does not get updated and has
 *       to be updated at a later time.
 */
static struct aa_label *__label_update(struct aa_label *label)
{
        struct aa_label *new, *tmp;
        struct aa_labelset *ls;
        unsigned long flags;
        int i, invcount = 0;

        AA_BUG(!label);
        AA_BUG(!mutex_is_locked(&labels_ns(label)->lock));

        new = aa_label_alloc(label->size, label->proxy, GFP_KERNEL);
        if (!new)
                return NULL;

        /*
         * while holding the ns_lock will stop profile replacement, removal,
         * and label updates, label merging and removal can be occurring
         */
        ls = labels_set(label);
        write_lock_irqsave(&ls->lock, flags);
        for (i = 0; i < label->size; i++) {
                AA_BUG(!label->vec[i]);
                new->vec[i] = aa_get_newest_profile(label->vec[i]);
                AA_BUG(!new->vec[i]);
                AA_BUG(!new->vec[i]->label.proxy);
                AA_BUG(!new->vec[i]->label.proxy->label);
                if (new->vec[i]->label.proxy != label->vec[i]->label.proxy)
                        invcount++;
        }

        /* updated stale label by being removed/renamed from labelset */
        if (invcount) {
                new->size -= aa_vec_unique(&new->vec[0], new->size,
                                           VEC_FLAG_TERMINATE);
                /* TODO: deal with reference labels */
                if (new->size == 1) {
                        tmp = aa_get_label(&new->vec[0]->label);
                        AA_BUG(tmp == label);
                        goto remove;
                }
                if (labels_set(label) != labels_set(new)) {
                        write_unlock_irqrestore(&ls->lock, flags);
                        tmp = aa_label_insert(labels_set(new), new);
                        write_lock_irqsave(&ls->lock, flags);
                        goto remove;
                }
        } else
                AA_BUG(labels_ns(label) != labels_ns(new));

        tmp = __label_insert(labels_set(label), new, true);
remove:
        /* ensure label is removed, and redirected correctly */
        __label_remove(label, tmp);
        write_unlock_irqrestore(&ls->lock, flags);
        label_free_or_put_new(tmp, new);

        return tmp;
}

/**
 * __labelset_update - update labels in @ns
 * @ns: namespace to update labels in  (NOT NULL)
 *
 * Requires: @ns lock be held
 *
 * Walk the labelset ensuring that all labels are up to date and valid
 * Any label that has a stale component is marked stale and replaced and
 * by an updated version.
 *
 * If failures happen due to memory pressures then stale labels will
 * be left in place until the next pass.
 */
static void __labelset_update(struct aa_ns *ns)
{
        struct aa_label *label;

        AA_BUG(!ns);
        AA_BUG(!mutex_is_locked(&ns->lock));

        do {
                label = labelset_next_stale(&ns->labels);
                if (label) {
                        struct aa_label *l = __label_update(label);

                        aa_put_label(l);
                        aa_put_label(label);
                }
        } while (label);
}

/**
 * __aa_labelset_udate_subtree - update all labels with a stale component
 * @ns: ns to start update at (NOT NULL)
 *
 * Requires: @ns lock be held
 *
 * Invalidates labels based on @p in @ns and any children namespaces.
 */
void __aa_labelset_update_subtree(struct aa_ns *ns)
{
        struct aa_ns *child;

        AA_BUG(!ns);
        AA_BUG(!mutex_is_locked(&ns->lock));

        __labelset_update(ns);

        list_for_each_entry(child, &ns->sub_ns, base.list) {
                mutex_lock_nested(&child->lock, child->level);
                __aa_labelset_update_subtree(child);
                mutex_unlock(&child->lock);
        }
}