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
  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         if (*pos != 0)
  46                 /* only writes from pos 0, that is complete writes */
  47                 return ERR_PTR(-ESPIPE);
  48
  49         /*
  50          * Don't allow profile load/replace/remove from profiles that don't
  51          * have CAP_MAC_ADMIN
  52          */
  53         if (!aa_may_manage_policy(op))
  54                 return ERR_PTR(-EACCES);
  55
  56         /* freed by caller to simple_write_to_buffer */
  57         data = kvmalloc(alloc_size);
  58         if (data == NULL)
  59                 return ERR_PTR(-ENOMEM);
  60
  61         if (copy_from_user(data, userbuf, copy_size)) {
  62                 kvfree(data);
  63                 return ERR_PTR(-EFAULT);
  64         }
  65
  66         return data;
  67 }
  68
  69
  70 /* .load file hook fn to load policy */
  71 static ssize_t profile_load(struct file *f, const char __user *buf, size_t size,
  72                             loff_t *pos)
  73 {
  74         char *data;
  75         ssize_t error;
  76
  77         data = aa_simple_write_to_buffer(OP_PROF_LOAD, buf, size, size, pos);
  78
  79         error = PTR_ERR(data);
  80         if (!IS_ERR(data)) {
  81                 error = aa_replace_profiles(data, size, PROF_ADD);
  82                 kvfree(data);
  83         }
  84
  85         return error;
  86 }
  87
  88 static const struct file_operations aa_fs_profile_load = {
  89         .write = profile_load
  90 };
  91
  92 /* .replace file hook fn to load and/or replace policy */
  93 static ssize_t profile_replace(struct file *f, const char __user *buf,
  94                                size_t size, loff_t *pos)
  95 {
  96         char *data;
  97         ssize_t error;
  98
  99         data = aa_simple_write_to_buffer(OP_PROF_REPL, buf, size, size, pos);
 100         error = PTR_ERR(data);
 101         if (!IS_ERR(data)) {
 102                 error = aa_replace_profiles(data, size, PROF_REPLACE);
 103                 kvfree(data);
 104         }
 105
 106         return error;
 107 }
 108
 109 static const struct file_operations aa_fs_profile_replace = {
 110         .write = profile_replace
 111 };
 112
 113 /* .remove file hook fn to remove loaded policy */
 114 static ssize_t profile_remove(struct file *f, const char __user *buf,
 115                               size_t size, loff_t *pos)
 116 {
 117         char *data;
 118         ssize_t error;
 119
 120         /*
 121          * aa_remove_profile needs a null terminated string so 1 extra
 122          * byte is allocated and the copied data is null terminated.
 123          */
 124         data = aa_simple_write_to_buffer(OP_PROF_RM, buf, size + 1, size, pos);
 125
 126         error = PTR_ERR(data);
 127         if (!IS_ERR(data)) {
 128                 data[size] = 0;
 129                 error = aa_remove_profiles(data, size);
 130                 kvfree(data);
 131         }
 132
 133         return error;
 134 }
 135
 136 static const struct file_operations aa_fs_profile_remove = {
 137         .write = profile_remove
 138 };
 139
 140 /** Base file system setup **/
 141
 142 static struct dentry *aa_fs_dentry __initdata;
 143
 144 static void __init aafs_remove(const char *name)
 145 {
 146         struct dentry *dentry;
 147
 148         dentry = lookup_one_len(name, aa_fs_dentry, strlen(name));
 149         if (!IS_ERR(dentry)) {
 150                 securityfs_remove(dentry);
 151                 dput(dentry);
 152         }
 153 }
 154
 155 /**
 156  * aafs_create - create an entry in the apparmor filesystem
 157  * @name: name of the entry (NOT NULL)
 158  * @mask: file permission mask of the file
 159  * @fops: file operations for the file (NOT NULL)
 160  *
 161  * Used aafs_remove to remove entries created with this fn.
 162  */
 163 static int __init aafs_create(const char *name, int mask,
 164                               const struct file_operations *fops)
 165 {
 166         struct dentry *dentry;
 167
 168         dentry = securityfs_create_file(name, S_IFREG | mask, aa_fs_dentry,
 169                                         NULL, fops);
 170
 171         return IS_ERR(dentry) ? PTR_ERR(dentry) : 0;
 172 }
 173
 174 /**
 175  * aa_destroy_aafs - cleanup and free aafs
 176  *
 177  * releases dentries allocated by aa_create_aafs
 178  */
 179 void __init aa_destroy_aafs(void)
 180 {
 181         if (aa_fs_dentry) {
 182                 aafs_remove(".remove");
 183                 aafs_remove(".replace");
 184                 aafs_remove(".load");
 185
 186                 securityfs_remove(aa_fs_dentry);
 187                 aa_fs_dentry = NULL;
 188         }
 189 }
 190
 191 /**
 192  * aa_create_aafs - create the apparmor security filesystem
 193  *
 194  * dentries created here are released by aa_destroy_aafs
 195  *
 196  * Returns: error on failure
 197  */
 198 int __init aa_create_aafs(void)
 199 {
 200         int error;
 201
 202         if (!apparmor_initialized)
 203                 return 0;
 204
 205         if (aa_fs_dentry) {
 206                 AA_ERROR("%s: AppArmor securityfs already exists\n", __func__);
 207                 return -EEXIST;
 208         }
 209
 210         aa_fs_dentry = securityfs_create_dir("apparmor", NULL);
 211         if (IS_ERR(aa_fs_dentry)) {
 212                 error = PTR_ERR(aa_fs_dentry);
 213                 aa_fs_dentry = NULL;
 214                 goto error;
 215         }
 216
 217         error = aafs_create(".load", 0640, &aa_fs_profile_load);
 218         if (error)
 219                 goto error;
 220         error = aafs_create(".replace", 0640, &aa_fs_profile_replace);
 221         if (error)
 222                 goto error;
 223         error = aafs_create(".remove", 0640, &aa_fs_profile_remove);
 224         if (error)
 225                 goto error;
 226
 227         /* TODO: add support for apparmorfs_null and apparmorfs_mnt */
 228
 229         /* Report that AppArmor fs is enabled */
 230         aa_info_message("AppArmor Filesystem Enabled");
 231         return 0;
 232
 233 error:
 234         aa_destroy_aafs();
 235         AA_ERROR("Error creating AppArmor securityfs\n");
 236         return error;
 237 }
 238
 239 fs_initcall(aa_create_aafs);