security/apparmor/apparmorfs.c

   1 /*
   2  * AppArmor security module
   3  *
   4  * This file contains AppArmor /sys/kernel/security/apparmor interface functions
   5  *
   6  * Copyright (C) 1998-2008 Novell/SUSE
   7  * Copyright 2009-2010 Canonical Ltd.
   8  *
   9  * This program is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU General Public License as
  11  * published by the Free Software Foundation, version 2 of the
  12  * License.
  13  */
  14
  15 #include <linux/security.h>
  16 #include <linux/vmalloc.h>
  17 #include <linux/module.h>
  18 #include <linux/seq_file.h>
  19 #include <linux/uaccess.h>
  20 #include <linux/namei.h>
  21
  22 #include "include/apparmor.h"
  23 #include "include/apparmorfs.h"
  24 #include "include/audit.h"
  25 #include "include/context.h"
  26 #include "include/policy.h"
  27
  28 /**
  29  * aa_simple_write_to_buffer - common routine for getting policy from user
  30  * @op: operation doing the user buffer copy
  31  * @userbuf: user buffer to copy data from  (NOT NULL)
  32  * @alloc_size: size of user buffer (REQUIRES: @alloc_size >= @copy_size)
  33  * @copy_size: size of data to copy from user buffer
  34  * @pos: position write is at in the file (NOT NULL)
  35  *
  36  * Returns: kernel buffer containing copy of user buffer data or an
  37  *          ERR_PTR on failure.
  38  */
  39 static char *aa_simple_write_to_buffer(int op, const char __user *userbuf,
  40                                        size_t alloc_size, size_t copy_size,
  41                                        loff_t *pos)
  42 {
  43         char *data;
  44
  45         BUG_ON(copy_size > alloc_size);
  46
  47         if (*pos != 0)
  48                 /* only writes from pos 0, that is complete writes */
  49                 return ERR_PTR(-ESPIPE);
  50
  51         /*
  52          * Don't allow profile load/replace/remove from profiles that don't
  53          * have CAP_MAC_ADMIN
  54          */
  55         if (!aa_may_manage_policy(op))
  56                 return ERR_PTR(-EACCES);
  57
  58         /* freed by caller to simple_write_to_buffer */
  59         data = kvmalloc(alloc_size);
  60         if (data == NULL)
  61                 return ERR_PTR(-ENOMEM);
  62
  63         if (copy_from_user(data, userbuf, copy_size)) {
  64                 kvfree(data);
  65                 return ERR_PTR(-EFAULT);
  66         }
  67
  68         return data;
  69 }
  70
  71
  72 /* .load file hook fn to load policy */
  73 static ssize_t profile_load(struct file *f, const char __user *buf, size_t size,
  74                             loff_t *pos)
  75 {
  76         char *data;
  77         ssize_t error;
  78
  79         data = aa_simple_write_to_buffer(OP_PROF_LOAD, buf, size, size, pos);
  80
  81         error = PTR_ERR(data);
  82         if (!IS_ERR(data)) {
  83                 error = aa_replace_profiles(data, size, PROF_ADD);
  84                 kvfree(data);
  85         }
  86
  87         return error;
  88 }
  89
  90 static const struct file_operations aa_fs_profile_load = {
  91         .write = profile_load,
  92         .llseek = default_llseek,
  93 };
  94
  95 /* .replace file hook fn to load and/or replace policy */
  96 static ssize_t profile_replace(struct file *f, const char __user *buf,
  97                                size_t size, loff_t *pos)
  98 {
  99         char *data;
 100         ssize_t error;
 101
 102         data = aa_simple_write_to_buffer(OP_PROF_REPL, buf, size, size, pos);
 103         error = PTR_ERR(data);
 104         if (!IS_ERR(data)) {
 105                 error = aa_replace_profiles(data, size, PROF_REPLACE);
 106                 kvfree(data);
 107         }
 108
 109         return error;
 110 }
 111
 112 static const struct file_operations aa_fs_profile_replace = {
 113         .write = profile_replace,
 114         .llseek = default_llseek,
 115 };
 116
 117 /* .remove file hook fn to remove loaded policy */
 118 static ssize_t profile_remove(struct file *f, const char __user *buf,
 119                               size_t size, loff_t *pos)
 120 {
 121         char *data;
 122         ssize_t error;
 123
 124         /*
 125          * aa_remove_profile needs a null terminated string so 1 extra
 126          * byte is allocated and the copied data is null terminated.
 127          */
 128         data = aa_simple_write_to_buffer(OP_PROF_RM, buf, size + 1, size, pos);
 129
 130         error = PTR_ERR(data);
 131         if (!IS_ERR(data)) {
 132                 data[size] = 0;
 133                 error = aa_remove_profiles(data, size);
 134                 kvfree(data);
 135         }
 136
 137         return error;
 138 }
 139
 140 static const struct file_operations aa_fs_profile_remove = {
 141         .write = profile_remove,
 142         .llseek = default_llseek,
 143 };
 144
 145 /** Base file system setup **/
 146
 147 static struct dentry *aa_fs_dentry __initdata;
 148
 149 static void __init aafs_remove(const char *name)
 150 {
 151         struct dentry *dentry;
 152
 153         dentry = lookup_one_len(name, aa_fs_dentry, strlen(name));
 154         if (!IS_ERR(dentry)) {
 155                 securityfs_remove(dentry);
 156                 dput(dentry);
 157         }
 158 }
 159
 160 /**
 161  * aafs_create - create an entry in the apparmor filesystem
 162  * @name: name of the entry (NOT NULL)
 163  * @mask: file permission mask of the file
 164  * @fops: file operations for the file (NOT NULL)
 165  *
 166  * Used aafs_remove to remove entries created with this fn.
 167  */
 168 static int __init aafs_create(const char *name, umode_t mask,
 169                               const struct file_operations *fops)
 170 {
 171         struct dentry *dentry;
 172
 173         dentry = securityfs_create_file(name, S_IFREG | mask, aa_fs_dentry,
 174                                         NULL, fops);
 175
 176         return IS_ERR(dentry) ? PTR_ERR(dentry) : 0;
 177 }
 178
 179 /**
 180  * aa_destroy_aafs - cleanup and free aafs
 181  *
 182  * releases dentries allocated by aa_create_aafs
 183  */
 184 void __init aa_destroy_aafs(void)
 185 {
 186         if (aa_fs_dentry) {
 187                 aafs_remove(".remove");
 188                 aafs_remove(".replace");
 189                 aafs_remove(".load");
 190
 191                 securityfs_remove(aa_fs_dentry);
 192                 aa_fs_dentry = NULL;
 193         }
 194 }
 195
 196 /**
 197  * aa_create_aafs - create the apparmor security filesystem
 198  *
 199  * dentries created here are released by aa_destroy_aafs
 200  *
 201  * Returns: error on failure
 202  */
 203 static int __init aa_create_aafs(void)
 204 {
 205         int error;
 206
 207         if (!apparmor_initialized)
 208                 return 0;
 209
 210         if (aa_fs_dentry) {
 211                 AA_ERROR("%s: AppArmor securityfs already exists\n", __func__);
 212                 return -EEXIST;
 213         }
 214
 215         aa_fs_dentry = securityfs_create_dir("apparmor", NULL);
 216         if (IS_ERR(aa_fs_dentry)) {
 217                 error = PTR_ERR(aa_fs_dentry);
 218                 aa_fs_dentry = NULL;
 219                 goto error;
 220         }
 221
 222         error = aafs_create(".load", 0640, &aa_fs_profile_load);
 223         if (error)
 224                 goto error;
 225         error = aafs_create(".replace", 0640, &aa_fs_profile_replace);
 226         if (error)
 227                 goto error;
 228         error = aafs_create(".remove", 0640, &aa_fs_profile_remove);
 229         if (error)
 230                 goto error;
 231
 232         /* TODO: add support for apparmorfs_null and apparmorfs_mnt */
 233
 234         /* Report that AppArmor fs is enabled */
 235         aa_info_message("AppArmor Filesystem Enabled");
 236         return 0;
 237
 238 error:
 239         aa_destroy_aafs();
 240         AA_ERROR("Error creating AppArmor securityfs\n");
 241         return error;
 242 }
 243
 244 fs_initcall(aa_create_aafs);