netdev-FAQ: clarify DaveM's position for stable backports

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

/*
 * AppArmor security module
 *
 * This file contains AppArmor /sys/kernel/security/apparmor interface 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.
 */

#include <linux/ctype.h>
#include <linux/security.h>
#include <linux/vmalloc.h>
#include <linux/module.h>
#include <linux/seq_file.h>
#include <linux/uaccess.h>
#include <linux/namei.h>
#include <linux/capability.h>
#include <linux/rcupdate.h>

#include "include/apparmor.h"
#include "include/apparmorfs.h"
#include "include/audit.h"
#include "include/context.h"
#include "include/crypto.h"
#include "include/policy.h"
#include "include/resource.h"

/**
 * aa_mangle_name - mangle a profile name to std profile layout form
 * @name: profile name to mangle  (NOT NULL)
 * @target: buffer to store mangled name, same length as @name (MAYBE NULL)
 *
 * Returns: length of mangled name
 */
static int mangle_name(char *name, char *target)
{
        char *t = target;

        while (*name == '/' || *name == '.')
                name++;

        if (target) {
                for (; *name; name++) {
                        if (*name == '/')
                                *(t)++ = '.';
                        else if (isspace(*name))
                                *(t)++ = '_';
                        else if (isalnum(*name) || strchr("._-", *name))
                                *(t)++ = *name;
                }

                *t = 0;
        } else {
                int len = 0;
                for (; *name; name++) {
                        if (isalnum(*name) || isspace(*name) ||
                            strchr("/._-", *name))
                                len++;
                }

                return len;
        }

        return t - target;
}

/**
 * aa_simple_write_to_buffer - common routine for getting policy from user
 * @op: operation doing the user buffer copy
 * @userbuf: user buffer to copy data from  (NOT NULL)
 * @alloc_size: size of user buffer (REQUIRES: @alloc_size >= @copy_size)
 * @copy_size: size of data to copy from user buffer
 * @pos: position write is at in the file (NOT NULL)
 *
 * Returns: kernel buffer containing copy of user buffer data or an
 *          ERR_PTR on failure.
 */
static char *aa_simple_write_to_buffer(int op, const char __user *userbuf,
                                       size_t alloc_size, size_t copy_size,
                                       loff_t *pos)
{
        char *data;

        BUG_ON(copy_size > alloc_size);

        if (*pos != 0)
                /* only writes from pos 0, that is complete writes */
                return ERR_PTR(-ESPIPE);

        /*
         * Don't allow profile load/replace/remove from profiles that don't
         * have CAP_MAC_ADMIN
         */
        if (!aa_may_manage_policy(op))
                return ERR_PTR(-EACCES);

        /* freed by caller to simple_write_to_buffer */
        data = kvmalloc(alloc_size);
        if (data == NULL)
                return ERR_PTR(-ENOMEM);

        if (copy_from_user(data, userbuf, copy_size)) {
                kvfree(data);
                return ERR_PTR(-EFAULT);
        }

        return data;
}


/* .load file hook fn to load policy */
static ssize_t profile_load(struct file *f, const char __user *buf, size_t size,
                            loff_t *pos)
{
        char *data;
        ssize_t error;

        data = aa_simple_write_to_buffer(OP_PROF_LOAD, buf, size, size, pos);

        error = PTR_ERR(data);
        if (!IS_ERR(data)) {
                error = aa_replace_profiles(data, size, PROF_ADD);
                kvfree(data);
        }

        return error;
}

static const struct file_operations aa_fs_profile_load = {
        .write = profile_load,
        .llseek = default_llseek,
};

/* .replace file hook fn to load and/or replace policy */
static ssize_t profile_replace(struct file *f, const char __user *buf,
                               size_t size, loff_t *pos)
{
        char *data;
        ssize_t error;

        data = aa_simple_write_to_buffer(OP_PROF_REPL, buf, size, size, pos);
        error = PTR_ERR(data);
        if (!IS_ERR(data)) {
                error = aa_replace_profiles(data, size, PROF_REPLACE);
                kvfree(data);
        }

        return error;
}

static const struct file_operations aa_fs_profile_replace = {
        .write = profile_replace,
        .llseek = default_llseek,
};

/* .remove file hook fn to remove loaded policy */
static ssize_t profile_remove(struct file *f, const char __user *buf,
                              size_t size, loff_t *pos)
{
        char *data;
        ssize_t error;

        /*
         * aa_remove_profile needs a null terminated string so 1 extra
         * byte is allocated and the copied data is null terminated.
         */
        data = aa_simple_write_to_buffer(OP_PROF_RM, buf, size + 1, size, pos);

        error = PTR_ERR(data);
        if (!IS_ERR(data)) {
                data[size] = 0;
                error = aa_remove_profiles(data, size);
                kvfree(data);
        }

        return error;
}

static const struct file_operations aa_fs_profile_remove = {
        .write = profile_remove,
        .llseek = default_llseek,
};

static int aa_fs_seq_show(struct seq_file *seq, void *v)
{
        struct aa_fs_entry *fs_file = seq->private;

        if (!fs_file)
                return 0;

        switch (fs_file->v_type) {
        case AA_FS_TYPE_BOOLEAN:
                seq_printf(seq, "%s\n", fs_file->v.boolean ? "yes" : "no");
                break;
        case AA_FS_TYPE_STRING:
                seq_printf(seq, "%s\n", fs_file->v.string);
                break;
        case AA_FS_TYPE_U64:
                seq_printf(seq, "%#08lx\n", fs_file->v.u64);
                break;
        default:
                /* Ignore unpritable entry types. */
                break;
        }

        return 0;
}

static int aa_fs_seq_open(struct inode *inode, struct file *file)
{
        return single_open(file, aa_fs_seq_show, inode->i_private);
}

const struct file_operations aa_fs_seq_file_ops = {
        .owner          = THIS_MODULE,
        .open           = aa_fs_seq_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};

static int aa_fs_seq_profile_open(struct inode *inode, struct file *file,
                                  int (*show)(struct seq_file *, void *))
{
        struct aa_replacedby *r = aa_get_replacedby(inode->i_private);
        int error = single_open(file, show, r);

        if (error) {
                file->private_data = NULL;
                aa_put_replacedby(r);
        }

        return error;
}

static int aa_fs_seq_profile_release(struct inode *inode, struct file *file)
{
        struct seq_file *seq = (struct seq_file *) file->private_data;
        if (seq)
                aa_put_replacedby(seq->private);
        return single_release(inode, file);
}

static int aa_fs_seq_profname_show(struct seq_file *seq, void *v)
{
        struct aa_replacedby *r = seq->private;
        struct aa_profile *profile = aa_get_profile_rcu(&r->profile);
        seq_printf(seq, "%s\n", profile->base.name);
        aa_put_profile(profile);

        return 0;
}

static int aa_fs_seq_profname_open(struct inode *inode, struct file *file)
{
        return aa_fs_seq_profile_open(inode, file, aa_fs_seq_profname_show);
}

static const struct file_operations aa_fs_profname_fops = {
        .owner          = THIS_MODULE,
        .open           = aa_fs_seq_profname_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = aa_fs_seq_profile_release,
};

static int aa_fs_seq_profmode_show(struct seq_file *seq, void *v)
{
        struct aa_replacedby *r = seq->private;
        struct aa_profile *profile = aa_get_profile_rcu(&r->profile);
        seq_printf(seq, "%s\n", aa_profile_mode_names[profile->mode]);
        aa_put_profile(profile);

        return 0;
}

static int aa_fs_seq_profmode_open(struct inode *inode, struct file *file)
{
        return aa_fs_seq_profile_open(inode, file, aa_fs_seq_profmode_show);
}

static const struct file_operations aa_fs_profmode_fops = {
        .owner          = THIS_MODULE,
        .open           = aa_fs_seq_profmode_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = aa_fs_seq_profile_release,
};

static int aa_fs_seq_profattach_show(struct seq_file *seq, void *v)
{
        struct aa_replacedby *r = seq->private;
        struct aa_profile *profile = aa_get_profile_rcu(&r->profile);
        if (profile->attach)
                seq_printf(seq, "%s\n", profile->attach);
        else if (profile->xmatch)
                seq_puts(seq, "<unknown>\n");
        else
                seq_printf(seq, "%s\n", profile->base.name);
        aa_put_profile(profile);

        return 0;
}

static int aa_fs_seq_profattach_open(struct inode *inode, struct file *file)
{
        return aa_fs_seq_profile_open(inode, file, aa_fs_seq_profattach_show);
}

static const struct file_operations aa_fs_profattach_fops = {
        .owner          = THIS_MODULE,
        .open           = aa_fs_seq_profattach_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = aa_fs_seq_profile_release,
};

static int aa_fs_seq_hash_show(struct seq_file *seq, void *v)
{
        struct aa_replacedby *r = seq->private;
        struct aa_profile *profile = aa_get_profile_rcu(&r->profile);
        unsigned int i, size = aa_hash_size();

        if (profile->hash) {
                for (i = 0; i < size; i++)
                        seq_printf(seq, "%.2x", profile->hash[i]);
                seq_puts(seq, "\n");
        }
        aa_put_profile(profile);

        return 0;
}

static int aa_fs_seq_hash_open(struct inode *inode, struct file *file)
{
        return single_open(file, aa_fs_seq_hash_show, inode->i_private);
}

static const struct file_operations aa_fs_seq_hash_fops = {
        .owner          = THIS_MODULE,
        .open           = aa_fs_seq_hash_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};

/** fns to setup dynamic per profile/namespace files **/
void __aa_fs_profile_rmdir(struct aa_profile *profile)
{
        struct aa_profile *child;
        int i;

        if (!profile)
                return;

        list_for_each_entry(child, &profile->base.profiles, base.list)
                __aa_fs_profile_rmdir(child);

        for (i = AAFS_PROF_SIZEOF - 1; i >= 0; --i) {
                struct aa_replacedby *r;
                if (!profile->dents[i])
                        continue;

                r = d_inode(profile->dents[i])->i_private;
                securityfs_remove(profile->dents[i]);
                aa_put_replacedby(r);
                profile->dents[i] = NULL;
        }
}

void __aa_fs_profile_migrate_dents(struct aa_profile *old,
                                   struct aa_profile *new)
{
        int i;

        for (i = 0; i < AAFS_PROF_SIZEOF; i++) {
                new->dents[i] = old->dents[i];
                if (new->dents[i])
                        new->dents[i]->d_inode->i_mtime = current_time(new->dents[i]->d_inode);
                old->dents[i] = NULL;
        }
}

static struct dentry *create_profile_file(struct dentry *dir, const char *name,
                                          struct aa_profile *profile,
                                          const struct file_operations *fops)
{
        struct aa_replacedby *r = aa_get_replacedby(profile->replacedby);
        struct dentry *dent;

        dent = securityfs_create_file(name, S_IFREG | 0444, dir, r, fops);
        if (IS_ERR(dent))
                aa_put_replacedby(r);

        return dent;
}

/* requires lock be held */
int __aa_fs_profile_mkdir(struct aa_profile *profile, struct dentry *parent)
{
        struct aa_profile *child;
        struct dentry *dent = NULL, *dir;
        int error;

        if (!parent) {
                struct aa_profile *p;
                p = aa_deref_parent(profile);
                dent = prof_dir(p);
                /* adding to parent that previously didn't have children */
                dent = securityfs_create_dir("profiles", dent);
                if (IS_ERR(dent))
                        goto fail;
                prof_child_dir(p) = parent = dent;
        }

        if (!profile->dirname) {
                int len, id_len;
                len = mangle_name(profile->base.name, NULL);
                id_len = snprintf(NULL, 0, ".%ld", profile->ns->uniq_id);

                profile->dirname = kmalloc(len + id_len + 1, GFP_KERNEL);
                if (!profile->dirname)
                        goto fail;

                mangle_name(profile->base.name, profile->dirname);
                sprintf(profile->dirname + len, ".%ld", profile->ns->uniq_id++);
        }

        dent = securityfs_create_dir(profile->dirname, parent);
        if (IS_ERR(dent))
                goto fail;
        prof_dir(profile) = dir = dent;

        dent = create_profile_file(dir, "name", profile, &aa_fs_profname_fops);
        if (IS_ERR(dent))
                goto fail;
        profile->dents[AAFS_PROF_NAME] = dent;

        dent = create_profile_file(dir, "mode", profile, &aa_fs_profmode_fops);
        if (IS_ERR(dent))
                goto fail;
        profile->dents[AAFS_PROF_MODE] = dent;

        dent = create_profile_file(dir, "attach", profile,
                                   &aa_fs_profattach_fops);
        if (IS_ERR(dent))
                goto fail;
        profile->dents[AAFS_PROF_ATTACH] = dent;

        if (profile->hash) {
                dent = create_profile_file(dir, "sha1", profile,
                                           &aa_fs_seq_hash_fops);
                if (IS_ERR(dent))
                        goto fail;
                profile->dents[AAFS_PROF_HASH] = dent;
        }

        list_for_each_entry(child, &profile->base.profiles, base.list) {
                error = __aa_fs_profile_mkdir(child, prof_child_dir(profile));
                if (error)
                        goto fail2;
        }

        return 0;

fail:
        error = PTR_ERR(dent);

fail2:
        __aa_fs_profile_rmdir(profile);

        return error;
}

void __aa_fs_namespace_rmdir(struct aa_namespace *ns)
{
        struct aa_namespace *sub;
        struct aa_profile *child;
        int i;

        if (!ns)
                return;

        list_for_each_entry(child, &ns->base.profiles, base.list)
                __aa_fs_profile_rmdir(child);

        list_for_each_entry(sub, &ns->sub_ns, base.list) {
                mutex_lock(&sub->lock);
                __aa_fs_namespace_rmdir(sub);
                mutex_unlock(&sub->lock);
        }

        for (i = AAFS_NS_SIZEOF - 1; i >= 0; --i) {
                securityfs_remove(ns->dents[i]);
                ns->dents[i] = NULL;
        }
}

int __aa_fs_namespace_mkdir(struct aa_namespace *ns, struct dentry *parent,
                            const char *name)
{
        struct aa_namespace *sub;
        struct aa_profile *child;
        struct dentry *dent, *dir;
        int error;

        if (!name)
                name = ns->base.name;

        dent = securityfs_create_dir(name, parent);
        if (IS_ERR(dent))
                goto fail;
        ns_dir(ns) = dir = dent;

        dent = securityfs_create_dir("profiles", dir);
        if (IS_ERR(dent))
                goto fail;
        ns_subprofs_dir(ns) = dent;

        dent = securityfs_create_dir("namespaces", dir);
        if (IS_ERR(dent))
                goto fail;
        ns_subns_dir(ns) = dent;

        list_for_each_entry(child, &ns->base.profiles, base.list) {
                error = __aa_fs_profile_mkdir(child, ns_subprofs_dir(ns));
                if (error)
                        goto fail2;
        }

        list_for_each_entry(sub, &ns->sub_ns, base.list) {
                mutex_lock(&sub->lock);
                error = __aa_fs_namespace_mkdir(sub, ns_subns_dir(ns), NULL);
                mutex_unlock(&sub->lock);
                if (error)
                        goto fail2;
        }

        return 0;

fail:
        error = PTR_ERR(dent);

fail2:
        __aa_fs_namespace_rmdir(ns);

        return error;
}


#define list_entry_is_head(pos, head, member) (&pos->member == (head))

/**
 * __next_namespace - find the next namespace to list
 * @root: root namespace to stop search at (NOT NULL)
 * @ns: current ns position (NOT NULL)
 *
 * Find the next namespace from @ns under @root and handle all locking needed
 * while switching current namespace.
 *
 * Returns: next namespace or NULL if at last namespace under @root
 * Requires: ns->parent->lock to be held
 * NOTE: will not unlock root->lock
 */
static struct aa_namespace *__next_namespace(struct aa_namespace *root,
                                             struct aa_namespace *ns)
{
        struct aa_namespace *parent, *next;

        /* is next namespace a child */
        if (!list_empty(&ns->sub_ns)) {
                next = list_first_entry(&ns->sub_ns, typeof(*ns), base.list);
                mutex_lock(&next->lock);
                return next;
        }

        /* check if the next ns is a sibling, parent, gp, .. */
        parent = ns->parent;
        while (ns != root) {
                mutex_unlock(&ns->lock);
                next = list_next_entry(ns, base.list);
                if (!list_entry_is_head(next, &parent->sub_ns, base.list)) {
                        mutex_lock(&next->lock);
                        return next;
                }
                ns = parent;
                parent = parent->parent;
        }

        return NULL;
}

/**
 * __first_profile - find the first profile in a namespace
 * @root: namespace that is root of profiles being displayed (NOT NULL)
 * @ns: namespace to start in   (NOT NULL)
 *
 * Returns: unrefcounted profile or NULL if no profile
 * Requires: profile->ns.lock to be held
 */
static struct aa_profile *__first_profile(struct aa_namespace *root,
                                          struct aa_namespace *ns)
{
        for (; ns; ns = __next_namespace(root, ns)) {
                if (!list_empty(&ns->base.profiles))
                        return list_first_entry(&ns->base.profiles,
                                                struct aa_profile, base.list);
        }
        return NULL;
}

/**
 * __next_profile - step to the next profile in a profile tree
 * @profile: current profile in tree (NOT NULL)
 *
 * Perform a depth first traversal on the profile tree in a namespace
 *
 * Returns: next profile or NULL if done
 * Requires: profile->ns.lock to be held
 */
static struct aa_profile *__next_profile(struct aa_profile *p)
{
        struct aa_profile *parent;
        struct aa_namespace *ns = p->ns;

        /* is next profile a child */
        if (!list_empty(&p->base.profiles))
                return list_first_entry(&p->base.profiles, typeof(*p),
                                        base.list);

        /* is next profile a sibling, parent sibling, gp, sibling, .. */
        parent = rcu_dereference_protected(p->parent,
                                           mutex_is_locked(&p->ns->lock));
        while (parent) {
                p = list_next_entry(p, base.list);
                if (!list_entry_is_head(p, &parent->base.profiles, base.list))
                        return p;
                p = parent;
                parent = rcu_dereference_protected(parent->parent,
                                            mutex_is_locked(&parent->ns->lock));
        }

        /* is next another profile in the namespace */
        p = list_next_entry(p, base.list);
        if (!list_entry_is_head(p, &ns->base.profiles, base.list))
                return p;

        return NULL;
}

/**
 * next_profile - step to the next profile in where ever it may be
 * @root: root namespace  (NOT NULL)
 * @profile: current profile  (NOT NULL)
 *
 * Returns: next profile or NULL if there isn't one
 */
static struct aa_profile *next_profile(struct aa_namespace *root,
                                       struct aa_profile *profile)
{
        struct aa_profile *next = __next_profile(profile);
        if (next)
                return next;

        /* finished all profiles in namespace move to next namespace */
        return __first_profile(root, __next_namespace(root, profile->ns));
}

/**
 * p_start - start a depth first traversal of profile tree
 * @f: seq_file to fill
 * @pos: current position
 *
 * Returns: first profile under current namespace or NULL if none found
 *
 * acquires first ns->lock
 */
static void *p_start(struct seq_file *f, loff_t *pos)
{
        struct aa_profile *profile = NULL;
        struct aa_namespace *root = aa_current_profile()->ns;
        loff_t l = *pos;
        f->private = aa_get_namespace(root);


        /* find the first profile */
        mutex_lock(&root->lock);
        profile = __first_profile(root, root);

        /* skip to position */
        for (; profile && l > 0; l--)
                profile = next_profile(root, profile);

        return profile;
}

/**
 * p_next - read the next profile entry
 * @f: seq_file to fill
 * @p: profile previously returned
 * @pos: current position
 *
 * Returns: next profile after @p or NULL if none
 *
 * may acquire/release locks in namespace tree as necessary
 */
static void *p_next(struct seq_file *f, void *p, loff_t *pos)
{
        struct aa_profile *profile = p;
        struct aa_namespace *ns = f->private;
        (*pos)++;

        return next_profile(ns, profile);
}

/**
 * p_stop - stop depth first traversal
 * @f: seq_file we are filling
 * @p: the last profile writen
 *
 * Release all locking done by p_start/p_next on namespace tree
 */
static void p_stop(struct seq_file *f, void *p)
{
        struct aa_profile *profile = p;
        struct aa_namespace *root = f->private, *ns;

        if (profile) {
                for (ns = profile->ns; ns && ns != root; ns = ns->parent)
                        mutex_unlock(&ns->lock);
        }
        mutex_unlock(&root->lock);
        aa_put_namespace(root);
}

/**
 * seq_show_profile - show a profile entry
 * @f: seq_file to file
 * @p: current position (profile)    (NOT NULL)
 *
 * Returns: error on failure
 */
static int seq_show_profile(struct seq_file *f, void *p)
{
        struct aa_profile *profile = (struct aa_profile *)p;
        struct aa_namespace *root = f->private;

        if (profile->ns != root)
                seq_printf(f, ":%s://", aa_ns_name(root, profile->ns));
        seq_printf(f, "%s (%s)\n", profile->base.hname,
                   aa_profile_mode_names[profile->mode]);

        return 0;
}

static const struct seq_operations aa_fs_profiles_op = {
        .start = p_start,
        .next = p_next,
        .stop = p_stop,
        .show = seq_show_profile,
};

static int profiles_open(struct inode *inode, struct file *file)
{
        return seq_open(file, &aa_fs_profiles_op);
}

static int profiles_release(struct inode *inode, struct file *file)
{
        return seq_release(inode, file);
}

static const struct file_operations aa_fs_profiles_fops = {
        .open = profiles_open,
        .read = seq_read,
        .llseek = seq_lseek,
        .release = profiles_release,
};


/** Base file system setup **/
static struct aa_fs_entry aa_fs_entry_file[] = {
        AA_FS_FILE_STRING("mask", "create read write exec append mmap_exec " \
                                  "link lock"),
        { }
};

static struct aa_fs_entry aa_fs_entry_domain[] = {
        AA_FS_FILE_BOOLEAN("change_hat",        1),
        AA_FS_FILE_BOOLEAN("change_hatv",       1),
        AA_FS_FILE_BOOLEAN("change_onexec",     1),
        AA_FS_FILE_BOOLEAN("change_profile",    1),
        { }
};

static struct aa_fs_entry aa_fs_entry_policy[] = {
        AA_FS_FILE_BOOLEAN("set_load",          1),
        {}
};

static struct aa_fs_entry aa_fs_entry_features[] = {
        AA_FS_DIR("policy",                     aa_fs_entry_policy),
        AA_FS_DIR("domain",                     aa_fs_entry_domain),
        AA_FS_DIR("file",                       aa_fs_entry_file),
        AA_FS_FILE_U64("capability",            VFS_CAP_FLAGS_MASK),
        AA_FS_DIR("rlimit",                     aa_fs_entry_rlimit),
        AA_FS_DIR("caps",                       aa_fs_entry_caps),
        { }
};

static struct aa_fs_entry aa_fs_entry_apparmor[] = {
        AA_FS_FILE_FOPS(".load", 0640, &aa_fs_profile_load),
        AA_FS_FILE_FOPS(".replace", 0640, &aa_fs_profile_replace),
        AA_FS_FILE_FOPS(".remove", 0640, &aa_fs_profile_remove),
        AA_FS_FILE_FOPS("profiles", 0640, &aa_fs_profiles_fops),
        AA_FS_DIR("features", aa_fs_entry_features),
        { }
};

static struct aa_fs_entry aa_fs_entry =
        AA_FS_DIR("apparmor", aa_fs_entry_apparmor);

/**
 * aafs_create_file - create a file entry in the apparmor securityfs
 * @fs_file: aa_fs_entry to build an entry for (NOT NULL)
 * @parent: the parent dentry in the securityfs
 *
 * Use aafs_remove_file to remove entries created with this fn.
 */
static int __init aafs_create_file(struct aa_fs_entry *fs_file,
                                   struct dentry *parent)
{
        int error = 0;

        fs_file->dentry = securityfs_create_file(fs_file->name,
                                                 S_IFREG | fs_file->mode,
                                                 parent, fs_file,
                                                 fs_file->file_ops);
        if (IS_ERR(fs_file->dentry)) {
                error = PTR_ERR(fs_file->dentry);
                fs_file->dentry = NULL;
        }
        return error;
}

static void __init aafs_remove_dir(struct aa_fs_entry *fs_dir);
/**
 * aafs_create_dir - recursively create a directory entry in the securityfs
 * @fs_dir: aa_fs_entry (and all child entries) to build (NOT NULL)
 * @parent: the parent dentry in the securityfs
 *
 * Use aafs_remove_dir to remove entries created with this fn.
 */
static int __init aafs_create_dir(struct aa_fs_entry *fs_dir,
                                  struct dentry *parent)
{
        struct aa_fs_entry *fs_file;
        struct dentry *dir;
        int error;

        dir = securityfs_create_dir(fs_dir->name, parent);
        if (IS_ERR(dir))
                return PTR_ERR(dir);
        fs_dir->dentry = dir;

        for (fs_file = fs_dir->v.files; fs_file && fs_file->name; ++fs_file) {
                if (fs_file->v_type == AA_FS_TYPE_DIR)
                        error = aafs_create_dir(fs_file, fs_dir->dentry);
                else
                        error = aafs_create_file(fs_file, fs_dir->dentry);
                if (error)
                        goto failed;
        }

        return 0;

failed:
        aafs_remove_dir(fs_dir);

        return error;
}

/**
 * aafs_remove_file - drop a single file entry in the apparmor securityfs
 * @fs_file: aa_fs_entry to detach from the securityfs (NOT NULL)
 */
static void __init aafs_remove_file(struct aa_fs_entry *fs_file)
{
        if (!fs_file->dentry)
                return;

        securityfs_remove(fs_file->dentry);
        fs_file->dentry = NULL;
}

/**
 * aafs_remove_dir - recursively drop a directory entry from the securityfs
 * @fs_dir: aa_fs_entry (and all child entries) to detach (NOT NULL)
 */
static void __init aafs_remove_dir(struct aa_fs_entry *fs_dir)
{
        struct aa_fs_entry *fs_file;

        for (fs_file = fs_dir->v.files; fs_file && fs_file->name; ++fs_file) {
                if (fs_file->v_type == AA_FS_TYPE_DIR)
                        aafs_remove_dir(fs_file);
                else
                        aafs_remove_file(fs_file);
        }

        aafs_remove_file(fs_dir);
}

/**
 * aa_destroy_aafs - cleanup and free aafs
 *
 * releases dentries allocated by aa_create_aafs
 */
void __init aa_destroy_aafs(void)
{
        aafs_remove_dir(&aa_fs_entry);
}

/**
 * aa_create_aafs - create the apparmor security filesystem
 *
 * dentries created here are released by aa_destroy_aafs
 *
 * Returns: error on failure
 */
static int __init aa_create_aafs(void)
{
        int error;

        if (!apparmor_initialized)
                return 0;

        if (aa_fs_entry.dentry) {
                AA_ERROR("%s: AppArmor securityfs already exists\n", __func__);
                return -EEXIST;
        }

        /* Populate fs tree. */
        error = aafs_create_dir(&aa_fs_entry, NULL);
        if (error)
                goto error;

        error = __aa_fs_namespace_mkdir(root_ns, aa_fs_entry.dentry,
                                        "policy");
        if (error)
                goto error;

        /* TODO: add support for apparmorfs_null and apparmorfs_mnt */

        /* Report that AppArmor fs is enabled */
        aa_info_message("AppArmor Filesystem Enabled");
        return 0;

error:
        aa_destroy_aafs();
        AA_ERROR("Error creating AppArmor securityfs\n");
        return error;
}

fs_initcall(aa_create_aafs);