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

/**
 * 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,
};

/** 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_features[] = {
        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),
        { }
};

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_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;
}

/**
 * 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)
{
        int error;
        struct aa_fs_entry *fs_file;

        fs_dir->dentry = securityfs_create_dir(fs_dir->name, parent);
        if (IS_ERR(fs_dir->dentry)) {
                error = PTR_ERR(fs_dir->dentry);
                fs_dir->dentry = NULL;
                goto failed;
        }

        for (fs_file = fs_dir->v.files; 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:
        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->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;

        /* 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);