apparmorfs.c

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/*
 * 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"

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 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);

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 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;
}

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;
}

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);
}

void __init aa_destroy_aafs(void)
{
    aafs_remove_dir(&aa_fs_entry);
}

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);