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 #include <linux/capability.h>
  22
  23 #include "include/apparmor.h"
  24 #include "include/apparmorfs.h"
  25 #include "include/audit.h"
  26 #include "include/context.h"
  27 #include "include/policy.h"
  28 #include "include/resource.h"
  29
  30 /**
  31  * aa_simple_write_to_buffer - common routine for getting policy from user
  32  * @op: operation doing the user buffer copy
  33  * @userbuf: user buffer to copy data from  (NOT NULL)
  34  * @alloc_size: size of user buffer (REQUIRES: @alloc_size >= @copy_size)
  35  * @copy_size: size of data to copy from user buffer
  36  * @pos: position write is at in the file (NOT NULL)
  37  *
  38  * Returns: kernel buffer containing copy of user buffer data or an
  39  *          ERR_PTR on failure.
  40  */
  41 static char *aa_simple_write_to_buffer(int op, const char __user *userbuf,
  42                                        size_t alloc_size, size_t copy_size,
  43                                        loff_t *pos)
  44 {
  45         char *data;
  46
  47         BUG_ON(copy_size > alloc_size);
  48
  49         if (*pos != 0)
  50                 /* only writes from pos 0, that is complete writes */
  51                 return ERR_PTR(-ESPIPE);
  52
  53         /*
  54          * Don't allow profile load/replace/remove from profiles that don't
  55          * have CAP_MAC_ADMIN
  56          */
  57         if (!aa_may_manage_policy(op))
  58                 return ERR_PTR(-EACCES);
  59
  60         /* freed by caller to simple_write_to_buffer */
  61         data = kvmalloc(alloc_size);
  62         if (data == NULL)
  63                 return ERR_PTR(-ENOMEM);
  64
  65         if (copy_from_user(data, userbuf, copy_size)) {
  66                 kvfree(data);
  67                 return ERR_PTR(-EFAULT);
  68         }
  69
  70         return data;
  71 }
  72
  73
  74 /* .load file hook fn to load policy */
  75 static ssize_t profile_load(struct file *f, const char __user *buf, size_t size,
  76                             loff_t *pos)
  77 {
  78         char *data;
  79         ssize_t error;
  80
  81         data = aa_simple_write_to_buffer(OP_PROF_LOAD, buf, size, size, pos);
  82
  83         error = PTR_ERR(data);
  84         if (!IS_ERR(data)) {
  85                 error = aa_replace_profiles(data, size, PROF_ADD);
  86                 kvfree(data);
  87         }
  88
  89         return error;
  90 }
  91
  92 static const struct file_operations aa_fs_profile_load = {
  93         .write = profile_load,
  94         .llseek = default_llseek,
  95 };
  96
  97 /* .replace file hook fn to load and/or replace policy */
  98 static ssize_t profile_replace(struct file *f, const char __user *buf,
  99                                size_t size, loff_t *pos)
 100 {
 101         char *data;
 102         ssize_t error;
 103
 104         data = aa_simple_write_to_buffer(OP_PROF_REPL, buf, size, size, pos);
 105         error = PTR_ERR(data);
 106         if (!IS_ERR(data)) {
 107                 error = aa_replace_profiles(data, size, PROF_REPLACE);
 108                 kvfree(data);
 109         }
 110
 111         return error;
 112 }
 113
 114 static const struct file_operations aa_fs_profile_replace = {
 115         .write = profile_replace,
 116         .llseek = default_llseek,
 117 };
 118
 119 /* .remove file hook fn to remove loaded policy */
 120 static ssize_t profile_remove(struct file *f, const char __user *buf,
 121                               size_t size, loff_t *pos)
 122 {
 123         char *data;
 124         ssize_t error;
 125
 126         /*
 127          * aa_remove_profile needs a null terminated string so 1 extra
 128          * byte is allocated and the copied data is null terminated.
 129          */
 130         data = aa_simple_write_to_buffer(OP_PROF_RM, buf, size + 1, size, pos);
 131
 132         error = PTR_ERR(data);
 133         if (!IS_ERR(data)) {
 134                 data[size] = 0;
 135                 error = aa_remove_profiles(data, size);
 136                 kvfree(data);
 137         }
 138
 139         return error;
 140 }
 141
 142 static const struct file_operations aa_fs_profile_remove = {
 143         .write = profile_remove,
 144         .llseek = default_llseek,
 145 };
 146
 147 static int aa_fs_seq_show(struct seq_file *seq, void *v)
 148 {
 149         struct aa_fs_entry *fs_file = seq->private;
 150
 151         if (!fs_file)
 152                 return 0;
 153
 154         switch (fs_file->v_type) {
 155         case AA_FS_TYPE_BOOLEAN:
 156                 seq_printf(seq, "%s\n", fs_file->v.boolean ? "yes" : "no");
 157                 break;
 158         case AA_FS_TYPE_STRING:
 159                 seq_printf(seq, "%s\n", fs_file->v.string);
 160                 break;
 161         case AA_FS_TYPE_U64:
 162                 seq_printf(seq, "%#08lx\n", fs_file->v.u64);
 163                 break;
 164         default:
 165                 /* Ignore unpritable entry types. */
 166                 break;
 167         }
 168
 169         return 0;
 170 }
 171
 172 static int aa_fs_seq_open(struct inode *inode, struct file *file)
 173 {
 174         return single_open(file, aa_fs_seq_show, inode->i_private);
 175 }
 176
 177 const struct file_operations aa_fs_seq_file_ops = {
 178         .owner          = THIS_MODULE,
 179         .open           = aa_fs_seq_open,
 180         .read           = seq_read,
 181         .llseek         = seq_lseek,
 182         .release        = single_release,
 183 };
 184
 185 /** Base file system setup **/
 186
 187 static struct aa_fs_entry aa_fs_entry_file[] = {
 188         AA_FS_FILE_STRING("mask", "create read write exec append mmap_exec " \
 189                                   "link lock"),
 190         { }
 191 };
 192
 193 static struct aa_fs_entry aa_fs_entry_domain[] = {
 194         AA_FS_FILE_BOOLEAN("change_hat",        1),
 195         AA_FS_FILE_BOOLEAN("change_hatv",       1),
 196         AA_FS_FILE_BOOLEAN("change_onexec",     1),
 197         AA_FS_FILE_BOOLEAN("change_profile",    1),
 198         { }
 199 };
 200
 201 static struct aa_fs_entry aa_fs_entry_features[] = {
 202         AA_FS_DIR("domain",                     aa_fs_entry_domain),
 203         AA_FS_DIR("file",                       aa_fs_entry_file),
 204         AA_FS_FILE_U64("capability",            VFS_CAP_FLAGS_MASK),
 205         AA_FS_DIR("rlimit",                     aa_fs_entry_rlimit),
 206         { }
 207 };
 208
 209 static struct aa_fs_entry aa_fs_entry_apparmor[] = {
 210         AA_FS_FILE_FOPS(".load", 0640, &aa_fs_profile_load),
 211         AA_FS_FILE_FOPS(".replace", 0640, &aa_fs_profile_replace),
 212         AA_FS_FILE_FOPS(".remove", 0640, &aa_fs_profile_remove),
 213         AA_FS_DIR("features", aa_fs_entry_features),
 214         { }
 215 };
 216
 217 static struct aa_fs_entry aa_fs_entry =
 218         AA_FS_DIR("apparmor", aa_fs_entry_apparmor);
 219
 220 /**
 221  * aafs_create_file - create a file entry in the apparmor securityfs
 222  * @fs_file: aa_fs_entry to build an entry for (NOT NULL)
 223  * @parent: the parent dentry in the securityfs
 224  *
 225  * Use aafs_remove_file to remove entries created with this fn.
 226  */
 227 static int __init aafs_create_file(struct aa_fs_entry *fs_file,
 228                                    struct dentry *parent)
 229 {
 230         int error = 0;
 231
 232         fs_file->dentry = securityfs_create_file(fs_file->name,
 233                                                  S_IFREG | fs_file->mode,
 234                                                  parent, fs_file,
 235                                                  fs_file->file_ops);
 236         if (IS_ERR(fs_file->dentry)) {
 237                 error = PTR_ERR(fs_file->dentry);
 238                 fs_file->dentry = NULL;
 239         }
 240         return error;
 241 }
 242
 243 /**
 244  * aafs_create_dir - recursively create a directory entry in the securityfs
 245  * @fs_dir: aa_fs_entry (and all child entries) to build (NOT NULL)
 246  * @parent: the parent dentry in the securityfs
 247  *
 248  * Use aafs_remove_dir to remove entries created with this fn.
 249  */
 250 static int __init aafs_create_dir(struct aa_fs_entry *fs_dir,
 251                                   struct dentry *parent)
 252 {
 253         int error;
 254         struct aa_fs_entry *fs_file;
 255
 256         fs_dir->dentry = securityfs_create_dir(fs_dir->name, parent);
 257         if (IS_ERR(fs_dir->dentry)) {
 258                 error = PTR_ERR(fs_dir->dentry);
 259                 fs_dir->dentry = NULL;
 260                 goto failed;
 261         }
 262
 263         for (fs_file = fs_dir->v.files; fs_file->name; ++fs_file) {
 264                 if (fs_file->v_type == AA_FS_TYPE_DIR)
 265                         error = aafs_create_dir(fs_file, fs_dir->dentry);
 266                 else
 267                         error = aafs_create_file(fs_file, fs_dir->dentry);
 268                 if (error)
 269                         goto failed;
 270         }
 271
 272         return 0;
 273
 274 failed:
 275         return error;
 276 }
 277
 278 /**
 279  * aafs_remove_file - drop a single file entry in the apparmor securityfs
 280  * @fs_file: aa_fs_entry to detach from the securityfs (NOT NULL)
 281  */
 282 static void __init aafs_remove_file(struct aa_fs_entry *fs_file)
 283 {
 284         if (!fs_file->dentry)
 285                 return;
 286
 287         securityfs_remove(fs_file->dentry);
 288         fs_file->dentry = NULL;
 289 }
 290
 291 /**
 292  * aafs_remove_dir - recursively drop a directory entry from the securityfs
 293  * @fs_dir: aa_fs_entry (and all child entries) to detach (NOT NULL)
 294  */
 295 static void __init aafs_remove_dir(struct aa_fs_entry *fs_dir)
 296 {
 297         struct aa_fs_entry *fs_file;
 298
 299         for (fs_file = fs_dir->v.files; fs_file->name; ++fs_file) {
 300                 if (fs_file->v_type == AA_FS_TYPE_DIR)
 301                         aafs_remove_dir(fs_file);
 302                 else
 303                         aafs_remove_file(fs_file);
 304         }
 305
 306         aafs_remove_file(fs_dir);
 307 }
 308
 309 /**
 310  * aa_destroy_aafs - cleanup and free aafs
 311  *
 312  * releases dentries allocated by aa_create_aafs
 313  */
 314 void __init aa_destroy_aafs(void)
 315 {
 316         aafs_remove_dir(&aa_fs_entry);
 317 }
 318
 319 /**
 320  * aa_create_aafs - create the apparmor security filesystem
 321  *
 322  * dentries created here are released by aa_destroy_aafs
 323  *
 324  * Returns: error on failure
 325  */
 326 static int __init aa_create_aafs(void)
 327 {
 328         int error;
 329
 330         if (!apparmor_initialized)
 331                 return 0;
 332
 333         if (aa_fs_entry.dentry) {
 334                 AA_ERROR("%s: AppArmor securityfs already exists\n", __func__);
 335                 return -EEXIST;
 336         }
 337
 338         /* Populate fs tree. */
 339         error = aafs_create_dir(&aa_fs_entry, NULL);
 340         if (error)
 341                 goto error;
 342
 343         /* TODO: add support for apparmorfs_null and apparmorfs_mnt */
 344
 345         /* Report that AppArmor fs is enabled */
 346         aa_info_message("AppArmor Filesystem Enabled");
 347         return 0;
 348
 349 error:
 350         aa_destroy_aafs();
 351         AA_ERROR("Error creating AppArmor securityfs\n");
 352         return error;
 353 }
 354
 355 fs_initcall(aa_create_aafs);