Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

[zen-stable.git] / security / apparmor / policy.c

/*
 * AppArmor security module
 *
 * This file contains AppArmor policy manipulation functions
 *
 * Copyright (C) 1998-2008 Novell/SUSE
 * Copyright 2009-2010 Canonical Ltd.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation, version 2 of the
 * License.
 *
 *
 * AppArmor policy is based around profiles, which contain the rules a
 * task is confined by.  Every task in the system has a profile attached
 * to it determined either by matching "unconfined" tasks against the
 * visible set of profiles or by following a profiles attachment rules.
 *
 * Each profile exists in a profile namespace which is a container of
 * visible profiles.  Each namespace contains a special "unconfined" profile,
 * which doesn't enforce any confinement on a task beyond DAC.
 *
 * Namespace and profile names can be written together in either
 * of two syntaxes.
 *      :namespace:profile - used by kernel interfaces for easy detection
 *      namespace://profile - used by policy
 *
 * Profile names can not start with : or @ or ^ and may not contain \0
 *
 * Reserved profile names
 *      unconfined - special automatically generated unconfined profile
 *      inherit - special name to indicate profile inheritance
 *      null-XXXX-YYYY - special automatically generated learning profiles
 *
 * Namespace names may not start with / or @ and may not contain \0 or :
 * Reserved namespace names
 *      user-XXXX - user defined profiles
 *
 * a // in a profile or namespace name indicates a hierarchical name with the
 * name before the // being the parent and the name after the child.
 *
 * Profile and namespace hierarchies serve two different but similar purposes.
 * The namespace contains the set of visible profiles that are considered
 * for attachment.  The hierarchy of namespaces allows for virtualizing
 * the namespace so that for example a chroot can have its own set of profiles
 * which may define some local user namespaces.
 * The profile hierarchy severs two distinct purposes,
 * -  it allows for sub profiles or hats, which allows an application to run
 *    subprograms under its own profile with different restriction than it
 *    self, and not have it use the system profile.
 *    eg. if a mail program starts an editor, the policy might make the
 *        restrictions tighter on the editor tighter than the mail program,
 *        and definitely different than general editor restrictions
 * - it allows for binary hierarchy of profiles, so that execution history
 *   is preserved.  This feature isn't exploited by AppArmor reference policy
 *   but is allowed.  NOTE: this is currently suboptimal because profile
 *   aliasing is not currently implemented so that a profile for each
 *   level must be defined.
 *   eg. /bin/bash///bin/ls as a name would indicate /bin/ls was started
 *       from /bin/bash
 *
 *   A profile or namespace name that can contain one or more // separators
 *   is referred to as an hname (hierarchical).
 *   eg.  /bin/bash//bin/ls
 *
 *   An fqname is a name that may contain both namespace and profile hnames.
 *   eg. :ns:/bin/bash//bin/ls
 *
 * NOTES:
 *   - locking of profile lists is currently fairly coarse.  All profile
 *     lists within a namespace use the namespace lock.
 * FIXME: move profile lists to using rcu_lists
 */

#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/string.h>

#include "include/apparmor.h"
#include "include/capability.h"
#include "include/context.h"
#include "include/file.h"
#include "include/ipc.h"
#include "include/match.h"
#include "include/path.h"
#include "include/policy.h"
#include "include/policy_unpack.h"
#include "include/resource.h"
#include "include/sid.h"


/* root profile namespace */
struct aa_namespace *root_ns;

const char *profile_mode_names[] = {
        "enforce",
        "complain",
        "kill",
};

/**
 * hname_tail - find the last component of an hname
 * @name: hname to find the base profile name component of  (NOT NULL)
 *
 * Returns: the tail (base profile name) name component of an hname
 */
static const char *hname_tail(const char *hname)
{
        char *split;
        hname = strim((char *)hname);
        for (split = strstr(hname, "//"); split; split = strstr(hname, "//"))
                hname = split + 2;

        return hname;
}

/**
 * policy_init - initialize a policy structure
 * @policy: policy to initialize  (NOT NULL)
 * @prefix: prefix name if any is required.  (MAYBE NULL)
 * @name: name of the policy, init will make a copy of it  (NOT NULL)
 *
 * Note: this fn creates a copy of strings passed in
 *
 * Returns: true if policy init successful
 */
static bool policy_init(struct aa_policy *policy, const char *prefix,
                        const char *name)
{
        /* freed by policy_free */
        if (prefix) {
                policy->hname = kmalloc(strlen(prefix) + strlen(name) + 3,
                                        GFP_KERNEL);
                if (policy->hname)
                        sprintf(policy->hname, "%s//%s", prefix, name);
        } else
                policy->hname = kstrdup(name, GFP_KERNEL);
        if (!policy->hname)
                return 0;
        /* base.name is a substring of fqname */
        policy->name = (char *)hname_tail(policy->hname);
        INIT_LIST_HEAD(&policy->list);
        INIT_LIST_HEAD(&policy->profiles);
        kref_init(&policy->count);

        return 1;
}

/**
 * policy_destroy - free the elements referenced by @policy
 * @policy: policy that is to have its elements freed  (NOT NULL)
 */
static void policy_destroy(struct aa_policy *policy)
{
        /* still contains profiles -- invalid */
        if (!list_empty(&policy->profiles)) {
                AA_ERROR("%s: internal error, "
                         "policy '%s' still contains profiles\n",
                         __func__, policy->name);
                BUG();
        }
        if (!list_empty(&policy->list)) {
                AA_ERROR("%s: internal error, policy '%s' still on list\n",
                         __func__, policy->name);
                BUG();
        }

        /* don't free name as its a subset of hname */
        kzfree(policy->hname);
}

/**
 * __policy_find - find a policy by @name on a policy list
 * @head: list to search  (NOT NULL)
 * @name: name to search for  (NOT NULL)
 *
 * Requires: correct locks for the @head list be held
 *
 * Returns: unrefcounted policy that match @name or NULL if not found
 */
static struct aa_policy *__policy_find(struct list_head *head, const char *name)
{
        struct aa_policy *policy;

        list_for_each_entry(policy, head, list) {
                if (!strcmp(policy->name, name))
                        return policy;
        }
        return NULL;
}

/**
 * __policy_strn_find - find a policy that's name matches @len chars of @str
 * @head: list to search  (NOT NULL)
 * @str: string to search for  (NOT NULL)
 * @len: length of match required
 *
 * Requires: correct locks for the @head list be held
 *
 * Returns: unrefcounted policy that match @str or NULL if not found
 *
 * if @len == strlen(@strlen) then this is equiv to __policy_find
 * other wise it allows searching for policy by a partial match of name
 */
static struct aa_policy *__policy_strn_find(struct list_head *head,
                                            const char *str, int len)
{
        struct aa_policy *policy;

        list_for_each_entry(policy, head, list) {
                if (aa_strneq(policy->name, str, len))
                        return policy;
        }

        return NULL;
}

/*
 * Routines for AppArmor namespaces
 */

static const char *hidden_ns_name = "---";
/**
 * aa_ns_visible - test if @view is visible from @curr
 * @curr: namespace to treat as the parent (NOT NULL)
 * @view:  namespace to test if visible from @curr (NOT NULL)
 *
 * Returns: true if @view is visible from @curr else false
 */
bool aa_ns_visible(struct aa_namespace *curr, struct aa_namespace *view)
{
        if (curr == view)
                return true;

        for ( ; view; view = view->parent) {
                if (view->parent == curr)
                        return true;
        }
        return false;
}

/**
 * aa_na_name - Find the ns name to display for @view from @curr
 * @curr - current namespace (NOT NULL)
 * @view - namespace attempting to view (NOT NULL)
 *
 * Returns: name of @view visible from @curr
 */
const char *aa_ns_name(struct aa_namespace *curr, struct aa_namespace *view)
{
        /* if view == curr then the namespace name isn't displayed */
        if (curr == view)
                return "";

        if (aa_ns_visible(curr, view)) {
                /* at this point if a ns is visible it is in a view ns
                 * thus the curr ns.hname is a prefix of its name.
                 * Only output the virtualized portion of the name
                 * Add + 2 to skip over // separating curr hname prefix
                 * from the visible tail of the views hname
                 */
                return view->base.hname + strlen(curr->base.hname) + 2;
        } else
                return hidden_ns_name;
}

/**
 * alloc_namespace - allocate, initialize and return a new namespace
 * @prefix: parent namespace name (MAYBE NULL)
 * @name: a preallocated name  (NOT NULL)
 *
 * Returns: refcounted namespace or NULL on failure.
 */
static struct aa_namespace *alloc_namespace(const char *prefix,
                                            const char *name)
{
        struct aa_namespace *ns;

        ns = kzalloc(sizeof(*ns), GFP_KERNEL);
        AA_DEBUG("%s(%p)\n", __func__, ns);
        if (!ns)
                return NULL;
        if (!policy_init(&ns->base, prefix, name))
                goto fail_ns;

        INIT_LIST_HEAD(&ns->sub_ns);
        rwlock_init(&ns->lock);

        /* released by free_namespace */
        ns->unconfined = aa_alloc_profile("unconfined");
        if (!ns->unconfined)
                goto fail_unconfined;

        ns->unconfined->sid = aa_alloc_sid();
        ns->unconfined->flags = PFLAG_UNCONFINED | PFLAG_IX_ON_NAME_ERROR |
            PFLAG_IMMUTABLE;

        /*
         * released by free_namespace, however __remove_namespace breaks
         * the cyclic references (ns->unconfined, and unconfined->ns) and
         * replaces with refs to parent namespace unconfined
         */
        ns->unconfined->ns = aa_get_namespace(ns);

        return ns;

fail_unconfined:
        kzfree(ns->base.hname);
fail_ns:
        kzfree(ns);
        return NULL;
}

/**
 * free_namespace - free a profile namespace
 * @ns: the namespace to free  (MAYBE NULL)
 *
 * Requires: All references to the namespace must have been put, if the
 *           namespace was referenced by a profile confining a task,
 */
static void free_namespace(struct aa_namespace *ns)
{
        if (!ns)
                return;

        policy_destroy(&ns->base);
        aa_put_namespace(ns->parent);

        if (ns->unconfined && ns->unconfined->ns == ns)
                ns->unconfined->ns = NULL;

        aa_put_profile(ns->unconfined);
        kzfree(ns);
}

/**
 * aa_free_namespace_kref - free aa_namespace by kref (see aa_put_namespace)
 * @kr: kref callback for freeing of a namespace  (NOT NULL)
 */
void aa_free_namespace_kref(struct kref *kref)
{
        free_namespace(container_of(kref, struct aa_namespace, base.count));
}

/**
 * __aa_find_namespace - find a namespace on a list by @name
 * @head: list to search for namespace on  (NOT NULL)
 * @name: name of namespace to look for  (NOT NULL)
 *
 * Returns: unrefcounted namespace
 *
 * Requires: ns lock be held
 */
static struct aa_namespace *__aa_find_namespace(struct list_head *head,
                                                const char *name)
{
        return (struct aa_namespace *)__policy_find(head, name);
}

/**
 * aa_find_namespace  -  look up a profile namespace on the namespace list
 * @root: namespace to search in  (NOT NULL)
 * @name: name of namespace to find  (NOT NULL)
 *
 * Returns: a refcounted namespace on the list, or NULL if no namespace
 *          called @name exists.
 *
 * refcount released by caller
 */
struct aa_namespace *aa_find_namespace(struct aa_namespace *root,
                                       const char *name)
{
        struct aa_namespace *ns = NULL;

        read_lock(&root->lock);
        ns = aa_get_namespace(__aa_find_namespace(&root->sub_ns, name));
        read_unlock(&root->lock);

        return ns;
}

/**
 * aa_prepare_namespace - find an existing or create a new namespace of @name
 * @name: the namespace to find or add  (MAYBE NULL)
 *
 * Returns: refcounted namespace or NULL if failed to create one
 */
static struct aa_namespace *aa_prepare_namespace(const char *name)
{
        struct aa_namespace *ns, *root;

        root = aa_current_profile()->ns;

        write_lock(&root->lock);

        /* if name isn't specified the profile is loaded to the current ns */
        if (!name) {
                /* released by caller */
                ns = aa_get_namespace(root);
                goto out;
        }

        /* try and find the specified ns and if it doesn't exist create it */
        /* released by caller */
        ns = aa_get_namespace(__aa_find_namespace(&root->sub_ns, name));
        if (!ns) {
                /* namespace not found */
                struct aa_namespace *new_ns;
                write_unlock(&root->lock);
                new_ns = alloc_namespace(root->base.hname, name);
                if (!new_ns)
                        return NULL;
                write_lock(&root->lock);
                /* test for race when new_ns was allocated */
                ns = __aa_find_namespace(&root->sub_ns, name);
                if (!ns) {
                        /* add parent ref */
                        new_ns->parent = aa_get_namespace(root);

                        list_add(&new_ns->base.list, &root->sub_ns);
                        /* add list ref */
                        ns = aa_get_namespace(new_ns);
                } else {
                        /* raced so free the new one */
                        free_namespace(new_ns);
                        /* get reference on namespace */
                        aa_get_namespace(ns);
                }
        }
out:
        write_unlock(&root->lock);

        /* return ref */
        return ns;
}

/**
 * __list_add_profile - add a profile to a list
 * @list: list to add it to  (NOT NULL)
 * @profile: the profile to add  (NOT NULL)
 *
 * refcount @profile, should be put by __list_remove_profile
 *
 * Requires: namespace lock be held, or list not be shared
 */
static void __list_add_profile(struct list_head *list,
                               struct aa_profile *profile)
{
        list_add(&profile->base.list, list);
        /* get list reference */
        aa_get_profile(profile);
}

/**
 * __list_remove_profile - remove a profile from the list it is on
 * @profile: the profile to remove  (NOT NULL)
 *
 * remove a profile from the list, warning generally removal should
 * be done with __replace_profile as most profile removals are
 * replacements to the unconfined profile.
 *
 * put @profile list refcount
 *
 * Requires: namespace lock be held, or list not have been live
 */
static void __list_remove_profile(struct aa_profile *profile)
{
        list_del_init(&profile->base.list);
        if (!(profile->flags & PFLAG_NO_LIST_REF))
                /* release list reference */
                aa_put_profile(profile);
}

/**
 * __replace_profile - replace @old with @new on a list
 * @old: profile to be replaced  (NOT NULL)
 * @new: profile to replace @old with  (NOT NULL)
 *
 * Will duplicate and refcount elements that @new inherits from @old
 * and will inherit @old children.
 *
 * refcount @new for list, put @old list refcount
 *
 * Requires: namespace list lock be held, or list not be shared
 */
static void __replace_profile(struct aa_profile *old, struct aa_profile *new)
{
        struct aa_policy *policy;
        struct aa_profile *child, *tmp;

        if (old->parent)
                policy = &old->parent->base;
        else
                policy = &old->ns->base;

        /* released when @new is freed */
        new->parent = aa_get_profile(old->parent);
        new->ns = aa_get_namespace(old->ns);
        new->sid = old->sid;
        __list_add_profile(&policy->profiles, new);
        /* inherit children */
        list_for_each_entry_safe(child, tmp, &old->base.profiles, base.list) {
                aa_put_profile(child->parent);
                child->parent = aa_get_profile(new);
                /* list refcount transferred to @new*/
                list_move(&child->base.list, &new->base.profiles);
        }

        /* released by free_profile */
        old->replacedby = aa_get_profile(new);
        __list_remove_profile(old);
}

static void __profile_list_release(struct list_head *head);

/**
 * __remove_profile - remove old profile, and children
 * @profile: profile to be replaced  (NOT NULL)
 *
 * Requires: namespace list lock be held, or list not be shared
 */
static void __remove_profile(struct aa_profile *profile)
{
        /* release any children lists first */
        __profile_list_release(&profile->base.profiles);
        /* released by free_profile */
        profile->replacedby = aa_get_profile(profile->ns->unconfined);
        __list_remove_profile(profile);
}

/**
 * __profile_list_release - remove all profiles on the list and put refs
 * @head: list of profiles  (NOT NULL)
 *
 * Requires: namespace lock be held
 */
static void __profile_list_release(struct list_head *head)
{
        struct aa_profile *profile, *tmp;
        list_for_each_entry_safe(profile, tmp, head, base.list)
                __remove_profile(profile);
}

static void __ns_list_release(struct list_head *head);

/**
 * destroy_namespace - remove everything contained by @ns
 * @ns: namespace to have it contents removed  (NOT NULL)
 */
static void destroy_namespace(struct aa_namespace *ns)
{
        if (!ns)
                return;

        write_lock(&ns->lock);
        /* release all profiles in this namespace */
        __profile_list_release(&ns->base.profiles);

        /* release all sub namespaces */
        __ns_list_release(&ns->sub_ns);

        write_unlock(&ns->lock);
}

/**
 * __remove_namespace - remove a namespace and all its children
 * @ns: namespace to be removed  (NOT NULL)
 *
 * Requires: ns->parent->lock be held and ns removed from parent.
 */
static void __remove_namespace(struct aa_namespace *ns)
{
        struct aa_profile *unconfined = ns->unconfined;

        /* remove ns from namespace list */
        list_del_init(&ns->base.list);

        /*
         * break the ns, unconfined profile cyclic reference and forward
         * all new unconfined profiles requests to the parent namespace
         * This will result in all confined tasks that have a profile
         * being removed, inheriting the parent->unconfined profile.
         */
        if (ns->parent)
                ns->unconfined = aa_get_profile(ns->parent->unconfined);

        destroy_namespace(ns);

        /* release original ns->unconfined ref */
        aa_put_profile(unconfined);
        /* release ns->base.list ref, from removal above */
        aa_put_namespace(ns);
}

/**
 * __ns_list_release - remove all profile namespaces on the list put refs
 * @head: list of profile namespaces  (NOT NULL)
 *
 * Requires: namespace lock be held
 */
static void __ns_list_release(struct list_head *head)
{
        struct aa_namespace *ns, *tmp;
        list_for_each_entry_safe(ns, tmp, head, base.list)
                __remove_namespace(ns);

}

/**
 * aa_alloc_root_ns - allocate the root profile namespace
 *
 * Returns: %0 on success else error
 *
 */
int __init aa_alloc_root_ns(void)
{
        /* released by aa_free_root_ns - used as list ref*/
        root_ns = alloc_namespace(NULL, "root");
        if (!root_ns)
                return -ENOMEM;

        return 0;
}

 /**
  * aa_free_root_ns - free the root profile namespace
  */
void __init aa_free_root_ns(void)
 {
         struct aa_namespace *ns = root_ns;
         root_ns = NULL;

         destroy_namespace(ns);
         aa_put_namespace(ns);
}

/**
 * aa_alloc_profile - allocate, initialize and return a new profile
 * @hname: name of the profile  (NOT NULL)
 *
 * Returns: refcount profile or NULL on failure
 */
struct aa_profile *aa_alloc_profile(const char *hname)
{
        struct aa_profile *profile;

        /* freed by free_profile - usually through aa_put_profile */
        profile = kzalloc(sizeof(*profile), GFP_KERNEL);
        if (!profile)
                return NULL;

        if (!policy_init(&profile->base, NULL, hname)) {
                kzfree(profile);
                return NULL;
        }

        /* refcount released by caller */
        return profile;
}

/**
 * aa_new_null_profile - create a new null-X learning profile
 * @parent: profile that caused this profile to be created (NOT NULL)
 * @hat: true if the null- learning profile is a hat
 *
 * Create a null- complain mode profile used in learning mode.  The name of
 * the profile is unique and follows the format of parent//null-sid.
 *
 * null profiles are added to the profile list but the list does not
 * hold a count on them so that they are automatically released when
 * not in use.
 *
 * Returns: new refcounted profile else NULL on failure
 */
struct aa_profile *aa_new_null_profile(struct aa_profile *parent, int hat)
{
        struct aa_profile *profile = NULL;
        char *name;
        u32 sid = aa_alloc_sid();

        /* freed below */
        name = kmalloc(strlen(parent->base.hname) + 2 + 7 + 8, GFP_KERNEL);
        if (!name)
                goto fail;
        sprintf(name, "%s//null-%x", parent->base.hname, sid);

        profile = aa_alloc_profile(name);
        kfree(name);
        if (!profile)
                goto fail;

        profile->sid = sid;
        profile->mode = APPARMOR_COMPLAIN;
        profile->flags = PFLAG_NULL;
        if (hat)
                profile->flags |= PFLAG_HAT;

        /* released on free_profile */
        profile->parent = aa_get_profile(parent);
        profile->ns = aa_get_namespace(parent->ns);

        write_lock(&profile->ns->lock);
        __list_add_profile(&parent->base.profiles, profile);
        write_unlock(&profile->ns->lock);

        /* refcount released by caller */
        return profile;

fail:
        aa_free_sid(sid);
        return NULL;
}

/**
 * free_profile - free a profile
 * @profile: the profile to free  (MAYBE NULL)
 *
 * Free a profile, its hats and null_profile. All references to the profile,
 * its hats and null_profile must have been put.
 *
 * If the profile was referenced from a task context, free_profile() will
 * be called from an rcu callback routine, so we must not sleep here.
 */
static void free_profile(struct aa_profile *profile)
{
        AA_DEBUG("%s(%p)\n", __func__, profile);

        if (!profile)
                return;

        if (!list_empty(&profile->base.list)) {
                AA_ERROR("%s: internal error, "
                         "profile '%s' still on ns list\n",
                         __func__, profile->base.name);
                BUG();
        }

        /* free children profiles */
        policy_destroy(&profile->base);
        aa_put_profile(profile->parent);

        aa_put_namespace(profile->ns);
        kzfree(profile->rename);

        aa_free_file_rules(&profile->file);
        aa_free_cap_rules(&profile->caps);
        aa_free_rlimit_rules(&profile->rlimits);

        aa_free_sid(profile->sid);
        aa_put_dfa(profile->xmatch);

        aa_put_profile(profile->replacedby);

        kzfree(profile);
}

/**
 * aa_free_profile_kref - free aa_profile by kref (called by aa_put_profile)
 * @kr: kref callback for freeing of a profile  (NOT NULL)
 */
void aa_free_profile_kref(struct kref *kref)
{
        struct aa_profile *p = container_of(kref, struct aa_profile,
                                            base.count);

        free_profile(p);
}

/* TODO: profile accounting - setup in remove */

/**
 * __find_child - find a profile on @head list with a name matching @name
 * @head: list to search  (NOT NULL)
 * @name: name of profile (NOT NULL)
 *
 * Requires: ns lock protecting list be held
 *
 * Returns: unrefcounted profile ptr, or NULL if not found
 */
static struct aa_profile *__find_child(struct list_head *head, const char *name)
{
        return (struct aa_profile *)__policy_find(head, name);
}

/**
 * __strn_find_child - find a profile on @head list using substring of @name
 * @head: list to search  (NOT NULL)
 * @name: name of profile (NOT NULL)
 * @len: length of @name substring to match
 *
 * Requires: ns lock protecting list be held
 *
 * Returns: unrefcounted profile ptr, or NULL if not found
 */
static struct aa_profile *__strn_find_child(struct list_head *head,
                                            const char *name, int len)
{
        return (struct aa_profile *)__policy_strn_find(head, name, len);
}

/**
 * aa_find_child - find a profile by @name in @parent
 * @parent: profile to search  (NOT NULL)
 * @name: profile name to search for  (NOT NULL)
 *
 * Returns: a refcounted profile or NULL if not found
 */
struct aa_profile *aa_find_child(struct aa_profile *parent, const char *name)
{
        struct aa_profile *profile;

        read_lock(&parent->ns->lock);
        profile = aa_get_profile(__find_child(&parent->base.profiles, name));
        read_unlock(&parent->ns->lock);

        /* refcount released by caller */
        return profile;
}

/**
 * __lookup_parent - lookup the parent of a profile of name @hname
 * @ns: namespace to lookup profile in  (NOT NULL)
 * @hname: hierarchical profile name to find parent of  (NOT NULL)
 *
 * Lookups up the parent of a fully qualified profile name, the profile
 * that matches hname does not need to exist, in general this
 * is used to load a new profile.
 *
 * Requires: ns->lock be held
 *
 * Returns: unrefcounted policy or NULL if not found
 */
static struct aa_policy *__lookup_parent(struct aa_namespace *ns,
                                         const char *hname)
{
        struct aa_policy *policy;
        struct aa_profile *profile = NULL;
        char *split;

        policy = &ns->base;

        for (split = strstr(hname, "//"); split;) {
                profile = __strn_find_child(&policy->profiles, hname,
                                            split - hname);
                if (!profile)
                        return NULL;
                policy = &profile->base;
                hname = split + 2;
                split = strstr(hname, "//");
        }
        if (!profile)
                return &ns->base;
        return &profile->base;
}

/**
 * __lookup_profile - lookup the profile matching @hname
 * @base: base list to start looking up profile name from  (NOT NULL)
 * @hname: hierarchical profile name  (NOT NULL)
 *
 * Requires: ns->lock be held
 *
 * Returns: unrefcounted profile pointer or NULL if not found
 *
 * Do a relative name lookup, recursing through profile tree.
 */
static struct aa_profile *__lookup_profile(struct aa_policy *base,
                                           const char *hname)
{
        struct aa_profile *profile = NULL;
        char *split;

        for (split = strstr(hname, "//"); split;) {
                profile = __strn_find_child(&base->profiles, hname,
                                            split - hname);
                if (!profile)
                        return NULL;

                base = &profile->base;
                hname = split + 2;
                split = strstr(hname, "//");
        }

        profile = __find_child(&base->profiles, hname);

        return profile;
}

/**
 * aa_lookup_profile - find a profile by its full or partial name
 * @ns: the namespace to start from (NOT NULL)
 * @hname: name to do lookup on.  Does not contain namespace prefix (NOT NULL)
 *
 * Returns: refcounted profile or NULL if not found
 */
struct aa_profile *aa_lookup_profile(struct aa_namespace *ns, const char *hname)
{
        struct aa_profile *profile;

        read_lock(&ns->lock);
        profile = aa_get_profile(__lookup_profile(&ns->base, hname));
        read_unlock(&ns->lock);

        /* refcount released by caller */
        return profile;
}

/**
 * replacement_allowed - test to see if replacement is allowed
 * @profile: profile to test if it can be replaced  (MAYBE NULL)
 * @noreplace: true if replacement shouldn't be allowed but addition is okay
 * @info: Returns - info about why replacement failed (NOT NULL)
 *
 * Returns: %0 if replacement allowed else error code
 */
static int replacement_allowed(struct aa_profile *profile, int noreplace,
                               const char **info)
{
        if (profile) {
                if (profile->flags & PFLAG_IMMUTABLE) {
                        *info = "cannot replace immutible profile";
                        return -EPERM;
                } else if (noreplace) {
                        *info = "profile already exists";
                        return -EEXIST;
                }
        }
        return 0;
}

/**
 * __add_new_profile - simple wrapper around __list_add_profile
 * @ns: namespace that profile is being added to  (NOT NULL)
 * @policy: the policy container to add the profile to  (NOT NULL)
 * @profile: profile to add  (NOT NULL)
 *
 * add a profile to a list and do other required basic allocations
 */
static void __add_new_profile(struct aa_namespace *ns, struct aa_policy *policy,
                              struct aa_profile *profile)
{
        if (policy != &ns->base)
                /* released on profile replacement or free_profile */
                profile->parent = aa_get_profile((struct aa_profile *) policy);
        __list_add_profile(&policy->profiles, profile);
        /* released on free_profile */
        profile->sid = aa_alloc_sid();
        profile->ns = aa_get_namespace(ns);
}

/**
 * aa_audit_policy - Do auditing of policy changes
 * @op: policy operation being performed
 * @gfp: memory allocation flags
 * @name: name of profile being manipulated (NOT NULL)
 * @info: any extra information to be audited (MAYBE NULL)
 * @error: error code
 *
 * Returns: the error to be returned after audit is done
 */
static int audit_policy(int op, gfp_t gfp, const char *name, const char *info,
                        int error)
{
        struct common_audit_data sa;
        COMMON_AUDIT_DATA_INIT(&sa, NONE);
        sa.aad.op = op;
        sa.aad.name = name;
        sa.aad.info = info;
        sa.aad.error = error;

        return aa_audit(AUDIT_APPARMOR_STATUS, __aa_current_profile(), gfp,
                        &sa, NULL);
}

/**
 * aa_may_manage_policy - can the current task manage policy
 * @op: the policy manipulation operation being done
 *
 * Returns: true if the task is allowed to manipulate policy
 */
bool aa_may_manage_policy(int op)
{
        /* check if loading policy is locked out */
        if (aa_g_lock_policy) {
                audit_policy(op, GFP_KERNEL, NULL, "policy_locked", -EACCES);
                return 0;
        }

        if (!capable(CAP_MAC_ADMIN)) {
                audit_policy(op, GFP_KERNEL, NULL, "not policy admin", -EACCES);
                return 0;
        }

        return 1;
}

/**
 * aa_replace_profiles - replace profile(s) on the profile list
 * @udata: serialized data stream  (NOT NULL)
 * @size: size of the serialized data stream
 * @noreplace: true if only doing addition, no replacement allowed
 *
 * unpack and replace a profile on the profile list and uses of that profile
 * by any aa_task_cxt.  If the profile does not exist on the profile list
 * it is added.
 *
 * Returns: size of data consumed else error code on failure.
 */
ssize_t aa_replace_profiles(void *udata, size_t size, bool noreplace)
{
        struct aa_policy *policy;
        struct aa_profile *old_profile = NULL, *new_profile = NULL;
        struct aa_profile *rename_profile = NULL;
        struct aa_namespace *ns = NULL;
        const char *ns_name, *name = NULL, *info = NULL;
        int op = OP_PROF_REPL;
        ssize_t error;

        /* released below */
        new_profile = aa_unpack(udata, size, &ns_name);
        if (IS_ERR(new_profile)) {
                error = PTR_ERR(new_profile);
                new_profile = NULL;
                goto fail;
        }

        /* released below */
        ns = aa_prepare_namespace(ns_name);
        if (!ns) {
                info = "failed to prepare namespace";
                error = -ENOMEM;
                name = ns_name;
                goto fail;
        }

        name = new_profile->base.hname;

        write_lock(&ns->lock);
        /* no ref on policy only use inside lock */
        policy = __lookup_parent(ns, new_profile->base.hname);

        if (!policy) {
                info = "parent does not exist";
                error = -ENOENT;
                goto audit;
        }

        old_profile = __find_child(&policy->profiles, new_profile->base.name);
        /* released below */
        aa_get_profile(old_profile);

        if (new_profile->rename) {
                rename_profile = __lookup_profile(&ns->base,
                                                  new_profile->rename);
                /* released below */
                aa_get_profile(rename_profile);

                if (!rename_profile) {
                        info = "profile to rename does not exist";
                        name = new_profile->rename;
                        error = -ENOENT;
                        goto audit;
                }
        }

        error = replacement_allowed(old_profile, noreplace, &info);
        if (error)
                goto audit;

        error = replacement_allowed(rename_profile, noreplace, &info);
        if (error)
                goto audit;

audit:
        if (!old_profile && !rename_profile)
                op = OP_PROF_LOAD;

        error = audit_policy(op, GFP_ATOMIC, name, info, error);

        if (!error) {
                if (rename_profile)
                        __replace_profile(rename_profile, new_profile);
                if (old_profile) {
                        /* when there are both rename and old profiles
                         * inherit old profiles sid
                         */
                        if (rename_profile)
                                aa_free_sid(new_profile->sid);
                        __replace_profile(old_profile, new_profile);
                }
                if (!(old_profile || rename_profile))
                        __add_new_profile(ns, policy, new_profile);
        }
        write_unlock(&ns->lock);

out:
        aa_put_namespace(ns);
        aa_put_profile(rename_profile);
        aa_put_profile(old_profile);
        aa_put_profile(new_profile);
        if (error)
                return error;
        return size;

fail:
        error = audit_policy(op, GFP_KERNEL, name, info, error);
        goto out;
}

/**
 * aa_remove_profiles - remove profile(s) from the system
 * @fqname: name of the profile or namespace to remove  (NOT NULL)
 * @size: size of the name
 *
 * Remove a profile or sub namespace from the current namespace, so that
 * they can not be found anymore and mark them as replaced by unconfined
 *
 * NOTE: removing confinement does not restore rlimits to preconfinemnet values
 *
 * Returns: size of data consume else error code if fails
 */
ssize_t aa_remove_profiles(char *fqname, size_t size)
{
        struct aa_namespace *root, *ns = NULL;
        struct aa_profile *profile = NULL;
        const char *name = fqname, *info = NULL;
        ssize_t error = 0;

        if (*fqname == 0) {
                info = "no profile specified";
                error = -ENOENT;
                goto fail;
        }

        root = aa_current_profile()->ns;

        if (fqname[0] == ':') {
                char *ns_name;
                name = aa_split_fqname(fqname, &ns_name);
                if (ns_name) {
                        /* released below */
                        ns = aa_find_namespace(root, ns_name);
                        if (!ns) {
                                info = "namespace does not exist";
                                error = -ENOENT;
                                goto fail;
                        }
                }
        } else
                /* released below */
                ns = aa_get_namespace(root);

        if (!name) {
                /* remove namespace - can only happen if fqname[0] == ':' */
                write_lock(&ns->parent->lock);
                __remove_namespace(ns);
                write_unlock(&ns->parent->lock);
        } else {
                /* remove profile */
                write_lock(&ns->lock);
                profile = aa_get_profile(__lookup_profile(&ns->base, name));
                if (!profile) {
                        error = -ENOENT;
                        info = "profile does not exist";
                        goto fail_ns_lock;
                }
                name = profile->base.hname;
                __remove_profile(profile);
                write_unlock(&ns->lock);
        }

        /* don't fail removal if audit fails */
        (void) audit_policy(OP_PROF_RM, GFP_KERNEL, name, info, error);
        aa_put_namespace(ns);
        aa_put_profile(profile);
        return size;

fail_ns_lock:
        write_unlock(&ns->lock);
        aa_put_namespace(ns);

fail:
        (void) audit_policy(OP_PROF_RM, GFP_KERNEL, name, info, error);
        return error;
}