security/tomoyo/mount.c

   1 /*
   2  * security/tomoyo/mount.c
   3  *
   4  * Copyright (C) 2005-2010  NTT DATA CORPORATION
   5  */
   6
   7 #include <linux/slab.h>
   8 #include "common.h"
   9
  10 /* Keywords for mount restrictions. */
  11
  12 /* Allow to call 'mount --bind /source_dir /dest_dir' */
  13 #define TOMOYO_MOUNT_BIND_KEYWORD                        "--bind"
  14 /* Allow to call 'mount --move /old_dir    /new_dir ' */
  15 #define TOMOYO_MOUNT_MOVE_KEYWORD                        "--move"
  16 /* Allow to call 'mount -o remount /dir             ' */
  17 #define TOMOYO_MOUNT_REMOUNT_KEYWORD                     "--remount"
  18 /* Allow to call 'mount --make-unbindable /dir'       */
  19 #define TOMOYO_MOUNT_MAKE_UNBINDABLE_KEYWORD             "--make-unbindable"
  20 /* Allow to call 'mount --make-private /dir'          */
  21 #define TOMOYO_MOUNT_MAKE_PRIVATE_KEYWORD                "--make-private"
  22 /* Allow to call 'mount --make-slave /dir'            */
  23 #define TOMOYO_MOUNT_MAKE_SLAVE_KEYWORD                  "--make-slave"
  24 /* Allow to call 'mount --make-shared /dir'           */
  25 #define TOMOYO_MOUNT_MAKE_SHARED_KEYWORD                 "--make-shared"
  26
  27 /**
  28  * tomoyo_encode2: Encode binary string to ascii string.
  29  *
  30  * @str: String in binary format.
  31  *
  32  * Returns pointer to @str in ascii format on success, NULL otherwise.
  33  *
  34  * This function uses kzalloc(), so caller must kfree() if this function
  35  * didn't return NULL.
  36  */
  37 static char *tomoyo_encode2(const char *str)
  38 {
  39         int len = 0;
  40         const char *p = str;
  41         char *cp;
  42         char *cp0;
  43         if (!p)
  44                 return NULL;
  45         while (*p) {
  46                 const unsigned char c = *p++;
  47                 if (c == '\\')
  48                         len += 2;
  49                 else if (c > ' ' && c < 127)
  50                         len++;
  51                 else
  52                         len += 4;
  53         }
  54         len++;
  55         /* Reserve space for appending "/". */
  56         cp = kzalloc(len + 10, GFP_NOFS);
  57         if (!cp)
  58                 return NULL;
  59         cp0 = cp;
  60         p = str;
  61         while (*p) {
  62                 const unsigned char c = *p++;
  63                 if (c == '\\') {
  64                         *cp++ = '\\';
  65                         *cp++ = '\\';
  66                 } else if (c > ' ' && c < 127) {
  67                         *cp++ = c;
  68                 } else {
  69                         *cp++ = '\\';
  70                         *cp++ = (c >> 6) + '0';
  71                         *cp++ = ((c >> 3) & 7) + '0';
  72                         *cp++ = (c & 7) + '0';
  73                 }
  74         }
  75         return cp0;
  76 }
  77
  78 /**
  79  * tomoyo_mount_acl2 - Check permission for mount() operation.
  80  *
  81  * @r:        Pointer to "struct tomoyo_request_info".
  82  * @dev_name: Name of device file.
  83  * @dir:      Pointer to "struct path".
  84  * @type:     Name of filesystem type.
  85  * @flags:    Mount options.
  86  *
  87  * Returns 0 on success, negative value otherwise.
  88  *
  89  * Caller holds tomoyo_read_lock().
  90  */
  91 static int tomoyo_mount_acl2(struct tomoyo_request_info *r, char *dev_name,
  92                              struct path *dir, char *type, unsigned long flags)
  93 {
  94         struct path path;
  95         struct tomoyo_acl_info *ptr;
  96         struct file_system_type *fstype = NULL;
  97         const char *requested_type = NULL;
  98         const char *requested_dir_name = NULL;
  99         const char *requested_dev_name = NULL;
 100         struct tomoyo_path_info rtype;
 101         struct tomoyo_path_info rdev;
 102         struct tomoyo_path_info rdir;
 103         int need_dev = 0;
 104         int error = -ENOMEM;
 105
 106         /* Get fstype. */
 107         requested_type = tomoyo_encode2(type);
 108         if (!requested_type)
 109                 goto out;
 110         rtype.name = requested_type;
 111         tomoyo_fill_path_info(&rtype);
 112
 113         /* Get mount point. */
 114         requested_dir_name = tomoyo_realpath_from_path(dir);
 115         if (!requested_dir_name) {
 116                 error = -ENOMEM;
 117                 goto out;
 118         }
 119         rdir.name = requested_dir_name;
 120         tomoyo_fill_path_info(&rdir);
 121
 122         /* Compare fs name. */
 123         if (!strcmp(type, TOMOYO_MOUNT_REMOUNT_KEYWORD)) {
 124                 /* dev_name is ignored. */
 125         } else if (!strcmp(type, TOMOYO_MOUNT_MAKE_UNBINDABLE_KEYWORD) ||
 126                    !strcmp(type, TOMOYO_MOUNT_MAKE_PRIVATE_KEYWORD) ||
 127                    !strcmp(type, TOMOYO_MOUNT_MAKE_SLAVE_KEYWORD) ||
 128                    !strcmp(type, TOMOYO_MOUNT_MAKE_SHARED_KEYWORD)) {
 129                 /* dev_name is ignored. */
 130         } else if (!strcmp(type, TOMOYO_MOUNT_BIND_KEYWORD) ||
 131                    !strcmp(type, TOMOYO_MOUNT_MOVE_KEYWORD)) {
 132                 need_dev = -1; /* dev_name is a directory */
 133         } else {
 134                 fstype = get_fs_type(type);
 135                 if (!fstype) {
 136                         error = -ENODEV;
 137                         goto out;
 138                 }
 139                 if (fstype->fs_flags & FS_REQUIRES_DEV)
 140                         /* dev_name is a block device file. */
 141                         need_dev = 1;
 142         }
 143         if (need_dev) {
 144                 /* Get mount point or device file. */
 145                 if (kern_path(dev_name, LOOKUP_FOLLOW, &path)) {
 146                         error = -ENOENT;
 147                         goto out;
 148                 }
 149                 requested_dev_name = tomoyo_realpath_from_path(&path);
 150                 if (!requested_dev_name) {
 151                         error = -ENOENT;
 152                         goto out;
 153                 }
 154         } else {
 155                 /* Map dev_name to "<NULL>" if no dev_name given. */
 156                 if (!dev_name)
 157                         dev_name = "<NULL>";
 158                 requested_dev_name = tomoyo_encode2(dev_name);
 159                 if (!requested_dev_name) {
 160                         error = -ENOMEM;
 161                         goto out;
 162                 }
 163         }
 164         rdev.name = requested_dev_name;
 165         tomoyo_fill_path_info(&rdev);
 166         list_for_each_entry_rcu(ptr, &r->domain->acl_info_list, list) {
 167                 struct tomoyo_mount_acl *acl;
 168                 if (ptr->type != TOMOYO_TYPE_MOUNT_ACL)
 169                         continue;
 170                 acl = container_of(ptr, struct tomoyo_mount_acl, head);
 171                 if (acl->is_deleted ||
 172                     !tomoyo_compare_number_union(flags, &acl->flags) ||
 173                     !tomoyo_compare_name_union(&rtype, &acl->fs_type) ||
 174                     !tomoyo_compare_name_union(&rdir, &acl->dir_name) ||
 175                     (need_dev &&
 176                      !tomoyo_compare_name_union(&rdev, &acl->dev_name)))
 177                         continue;
 178                 error = 0;
 179                 break;
 180         }
 181         if (error) {
 182                 const char *dev = tomoyo_get_file_pattern(&rdev)->name;
 183                 const char *dir = tomoyo_get_file_pattern(&rdir)->name;
 184                 int len = strlen(dev) + strlen(dir) + strlen(requested_type)
 185                         + 64;
 186                 char *buf = kzalloc(len, GFP_NOFS);
 187                 if (buf) {
 188                         snprintf(buf, len - 1, "%s %s %s 0x%lX",
 189                                  dev, dir, requested_type, flags);
 190                         tomoyo_write_mount_policy(buf, r->domain, false);
 191                         kfree(buf);
 192                 }
 193         }
 194  out:
 195         kfree(requested_dev_name);
 196         kfree(requested_dir_name);
 197         if (fstype)
 198                 put_filesystem(fstype);
 199         kfree(requested_type);
 200         return error;
 201 }
 202
 203 /**
 204  * tomoyo_mount_acl - Check permission for mount() operation.
 205  *
 206  * @r:        Pointer to "struct tomoyo_request_info".
 207  * @dev_name: Name of device file.
 208  * @dir:      Pointer to "struct path".
 209  * @type:     Name of filesystem type.
 210  * @flags:    Mount options.
 211  *
 212  * Returns 0 on success, negative value otherwise.
 213  *
 214  * Caller holds tomoyo_read_lock().
 215  */
 216 static int tomoyo_mount_acl(struct tomoyo_request_info *r, char *dev_name,
 217                             struct path *dir, char *type, unsigned long flags)
 218 {
 219         int error;
 220         error = -EPERM;
 221         if ((flags & MS_MGC_MSK) == MS_MGC_VAL)
 222                 flags &= ~MS_MGC_MSK;
 223         switch (flags & (MS_REMOUNT | MS_MOVE | MS_BIND)) {
 224         case MS_REMOUNT:
 225         case MS_MOVE:
 226         case MS_BIND:
 227         case 0:
 228                 break;
 229         default:
 230                 printk(KERN_WARNING "ERROR: "
 231                        "%s%s%sare given for single mount operation.\n",
 232                        flags & MS_REMOUNT ? "'remount' " : "",
 233                        flags & MS_MOVE    ? "'move' " : "",
 234                        flags & MS_BIND    ? "'bind' " : "");
 235                 return -EINVAL;
 236         }
 237         switch (flags & (MS_UNBINDABLE | MS_PRIVATE | MS_SLAVE | MS_SHARED)) {
 238         case MS_UNBINDABLE:
 239         case MS_PRIVATE:
 240         case MS_SLAVE:
 241         case MS_SHARED:
 242         case 0:
 243                 break;
 244         default:
 245                 printk(KERN_WARNING "ERROR: "
 246                        "%s%s%s%sare given for single mount operation.\n",
 247                        flags & MS_UNBINDABLE ? "'unbindable' " : "",
 248                        flags & MS_PRIVATE    ? "'private' " : "",
 249                        flags & MS_SLAVE      ? "'slave' " : "",
 250                        flags & MS_SHARED     ? "'shared' " : "");
 251                 return -EINVAL;
 252         }
 253         if (flags & MS_REMOUNT)
 254                 error = tomoyo_mount_acl(r, dev_name, dir,
 255                                       TOMOYO_MOUNT_REMOUNT_KEYWORD,
 256                                       flags & ~MS_REMOUNT);
 257         else if (flags & MS_MOVE)
 258                 error = tomoyo_mount_acl(r, dev_name, dir,
 259                                       TOMOYO_MOUNT_MOVE_KEYWORD,
 260                                       flags & ~MS_MOVE);
 261         else if (flags & MS_BIND)
 262                 error = tomoyo_mount_acl(r, dev_name, dir,
 263                                       TOMOYO_MOUNT_BIND_KEYWORD,
 264                                       flags & ~MS_BIND);
 265         else if (flags & MS_UNBINDABLE)
 266                 error = tomoyo_mount_acl(r, dev_name, dir,
 267                                       TOMOYO_MOUNT_MAKE_UNBINDABLE_KEYWORD,
 268                                       flags & ~MS_UNBINDABLE);
 269         else if (flags & MS_PRIVATE)
 270                 error = tomoyo_mount_acl(r, dev_name, dir,
 271                                       TOMOYO_MOUNT_MAKE_PRIVATE_KEYWORD,
 272                                       flags & ~MS_PRIVATE);
 273         else if (flags & MS_SLAVE)
 274                 error = tomoyo_mount_acl(r, dev_name, dir,
 275                                       TOMOYO_MOUNT_MAKE_SLAVE_KEYWORD,
 276                                       flags & ~MS_SLAVE);
 277         else if (flags & MS_SHARED)
 278                 error = tomoyo_mount_acl(r, dev_name, dir,
 279                                       TOMOYO_MOUNT_MAKE_SHARED_KEYWORD,
 280                                       flags & ~MS_SHARED);
 281         else
 282                 error = tomoyo_mount_acl2(r, dev_name, dir, type, flags);
 283         if (r->mode != TOMOYO_CONFIG_ENFORCING)
 284                 error = 0;
 285         return error;
 286 }
 287
 288 /**
 289  * tomoyo_mount_permission - Check permission for mount() operation.
 290  *
 291  * @dev_name:  Name of device file.
 292  * @path:      Pointer to "struct path".
 293  * @type:      Name of filesystem type. May be NULL.
 294  * @flags:     Mount options.
 295  * @data_page: Optional data. May be NULL.
 296  *
 297  * Returns 0 on success, negative value otherwise.
 298  */
 299 int tomoyo_mount_permission(char *dev_name, struct path *path, char *type,
 300                             unsigned long flags, void *data_page)
 301 {
 302         struct tomoyo_request_info r;
 303         int error;
 304         int idx;
 305
 306         if (tomoyo_init_request_info(&r, NULL) == TOMOYO_CONFIG_DISABLED)
 307                 return 0;
 308         if (!type)
 309                 type = "<NULL>";
 310         idx = tomoyo_read_lock();
 311         error = tomoyo_mount_acl(&r, dev_name, path, type, flags);
 312         tomoyo_read_unlock(idx);
 313         return error;
 314 }
 315
 316 /**
 317  * tomoyo_write_mount_policy - Write "struct tomoyo_mount_acl" list.
 318  *
 319  * @data:      String to parse.
 320  * @domain:    Pointer to "struct tomoyo_domain_info".
 321  * @is_delete: True if it is a delete request.
 322  *
 323  * Returns 0 on success, negative value otherwise.
 324  */
 325 int tomoyo_write_mount_policy(char *data, struct tomoyo_domain_info *domain,
 326                               const bool is_delete)
 327 {
 328         struct tomoyo_acl_info *ptr;
 329         struct tomoyo_mount_acl e = { .head.type = TOMOYO_TYPE_MOUNT_ACL };
 330         int error = is_delete ? -ENOENT : -ENOMEM;
 331         char *w[4];
 332         if (!tomoyo_tokenize(data, w, sizeof(w)) || !w[3][0])
 333                 return -EINVAL;
 334         if (!tomoyo_parse_name_union(w[0], &e.dev_name) ||
 335             !tomoyo_parse_name_union(w[1], &e.dir_name) ||
 336             !tomoyo_parse_name_union(w[2], &e.fs_type) ||
 337             !tomoyo_parse_number_union(w[3], &e.flags))
 338                 goto out;
 339         if (mutex_lock_interruptible(&tomoyo_policy_lock))
 340                 goto out;
 341         list_for_each_entry_rcu(ptr, &domain->acl_info_list, list) {
 342                 struct tomoyo_mount_acl *acl =
 343                         container_of(ptr, struct tomoyo_mount_acl, head);
 344                 if (!tomoyo_is_same_mount_acl(acl, &e))
 345                         continue;
 346                 acl->is_deleted = is_delete;
 347                 error = 0;
 348                 break;
 349         }
 350         if (!is_delete && error) {
 351                 struct tomoyo_mount_acl *entry =
 352                         tomoyo_commit_ok(&e, sizeof(e));
 353                 if (entry) {
 354                         list_add_tail_rcu(&entry->head.list,
 355                                           &domain->acl_info_list);
 356                         error = 0;
 357                 }
 358         }
 359         mutex_unlock(&tomoyo_policy_lock);
 360  out:
 361         tomoyo_put_name_union(&e.dev_name);
 362         tomoyo_put_name_union(&e.dir_name);
 363         tomoyo_put_name_union(&e.fs_type);
 364         tomoyo_put_number_union(&e.flags);
 365         return error;
 366 }