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_audit_mount_log - Audit mount log.
  29  *
  30  * @r: Pointer to "struct tomoyo_request_info".
  31  *
  32  * Returns 0 on success, negative value otherwise.
  33  */
  34 static int tomoyo_audit_mount_log(struct tomoyo_request_info *r)
  35 {
  36         const char *dev = r->param.mount.dev->name;
  37         const char *dir = r->param.mount.dir->name;
  38         const char *type = r->param.mount.type->name;
  39         const unsigned long flags = r->param.mount.flags;
  40         if (r->granted)
  41                 return 0;
  42         if (!strcmp(type, TOMOYO_MOUNT_REMOUNT_KEYWORD))
  43                 tomoyo_warn_log(r, "mount -o remount %s 0x%lX", dir, flags);
  44         else if (!strcmp(type, TOMOYO_MOUNT_BIND_KEYWORD)
  45                  || !strcmp(type, TOMOYO_MOUNT_MOVE_KEYWORD))
  46                 tomoyo_warn_log(r, "mount %s %s %s 0x%lX", type, dev, dir,
  47                                 flags);
  48         else if (!strcmp(type, TOMOYO_MOUNT_MAKE_UNBINDABLE_KEYWORD) ||
  49                  !strcmp(type, TOMOYO_MOUNT_MAKE_PRIVATE_KEYWORD) ||
  50                  !strcmp(type, TOMOYO_MOUNT_MAKE_SLAVE_KEYWORD) ||
  51                  !strcmp(type, TOMOYO_MOUNT_MAKE_SHARED_KEYWORD))
  52                 tomoyo_warn_log(r, "mount %s %s 0x%lX", type, dir, flags);
  53         else
  54                 tomoyo_warn_log(r, "mount -t %s %s %s 0x%lX", type, dev, dir,
  55                                 flags);
  56         return tomoyo_supervisor(r,
  57                                  TOMOYO_KEYWORD_ALLOW_MOUNT "%s %s %s 0x%lX\n",
  58                                  tomoyo_pattern(r->param.mount.dev),
  59                                  tomoyo_pattern(r->param.mount.dir), type,
  60                                  flags);
  61 }
  62
  63 static bool tomoyo_check_mount_acl(struct tomoyo_request_info *r,
  64                                    const struct tomoyo_acl_info *ptr)
  65 {
  66         const struct tomoyo_mount_acl *acl =
  67                 container_of(ptr, typeof(*acl), head);
  68         return tomoyo_compare_number_union(r->param.mount.flags, &acl->flags) &&
  69                 tomoyo_compare_name_union(r->param.mount.type, &acl->fs_type) &&
  70                 tomoyo_compare_name_union(r->param.mount.dir, &acl->dir_name) &&
  71                 (!r->param.mount.need_dev ||
  72                  tomoyo_compare_name_union(r->param.mount.dev, &acl->dev_name));
  73 }
  74
  75 /**
  76  * tomoyo_mount_acl - Check permission for mount() operation.
  77  *
  78  * @r:        Pointer to "struct tomoyo_request_info".
  79  * @dev_name: Name of device file.
  80  * @dir:      Pointer to "struct path".
  81  * @type:     Name of filesystem type.
  82  * @flags:    Mount options.
  83  *
  84  * Returns 0 on success, negative value otherwise.
  85  *
  86  * Caller holds tomoyo_read_lock().
  87  */
  88 static int tomoyo_mount_acl(struct tomoyo_request_info *r, char *dev_name,
  89                             struct path *dir, char *type, unsigned long flags)
  90 {
  91         struct path path;
  92         struct file_system_type *fstype = NULL;
  93         const char *requested_type = NULL;
  94         const char *requested_dir_name = NULL;
  95         const char *requested_dev_name = NULL;
  96         struct tomoyo_path_info rtype;
  97         struct tomoyo_path_info rdev;
  98         struct tomoyo_path_info rdir;
  99         int need_dev = 0;
 100         int error = -ENOMEM;
 101
 102         /* Get fstype. */
 103         requested_type = tomoyo_encode(type);
 104         if (!requested_type)
 105                 goto out;
 106         rtype.name = requested_type;
 107         tomoyo_fill_path_info(&rtype);
 108
 109         /* Get mount point. */
 110         requested_dir_name = tomoyo_realpath_from_path(dir);
 111         if (!requested_dir_name) {
 112                 error = -ENOMEM;
 113                 goto out;
 114         }
 115         rdir.name = requested_dir_name;
 116         tomoyo_fill_path_info(&rdir);
 117
 118         /* Compare fs name. */
 119         if (!strcmp(type, TOMOYO_MOUNT_REMOUNT_KEYWORD)) {
 120                 /* dev_name is ignored. */
 121         } else if (!strcmp(type, TOMOYO_MOUNT_MAKE_UNBINDABLE_KEYWORD) ||
 122                    !strcmp(type, TOMOYO_MOUNT_MAKE_PRIVATE_KEYWORD) ||
 123                    !strcmp(type, TOMOYO_MOUNT_MAKE_SLAVE_KEYWORD) ||
 124                    !strcmp(type, TOMOYO_MOUNT_MAKE_SHARED_KEYWORD)) {
 125                 /* dev_name is ignored. */
 126         } else if (!strcmp(type, TOMOYO_MOUNT_BIND_KEYWORD) ||
 127                    !strcmp(type, TOMOYO_MOUNT_MOVE_KEYWORD)) {
 128                 need_dev = -1; /* dev_name is a directory */
 129         } else {
 130                 fstype = get_fs_type(type);
 131                 if (!fstype) {
 132                         error = -ENODEV;
 133                         goto out;
 134                 }
 135                 if (fstype->fs_flags & FS_REQUIRES_DEV)
 136                         /* dev_name is a block device file. */
 137                         need_dev = 1;
 138         }
 139         if (need_dev) {
 140                 /* Get mount point or device file. */
 141                 if (kern_path(dev_name, LOOKUP_FOLLOW, &path)) {
 142                         error = -ENOENT;
 143                         goto out;
 144                 }
 145                 requested_dev_name = tomoyo_realpath_from_path(&path);
 146                 if (!requested_dev_name) {
 147                         error = -ENOENT;
 148                         goto out;
 149                 }
 150         } else {
 151                 /* Map dev_name to "<NULL>" if no dev_name given. */
 152                 if (!dev_name)
 153                         dev_name = "<NULL>";
 154                 requested_dev_name = tomoyo_encode(dev_name);
 155                 if (!requested_dev_name) {
 156                         error = -ENOMEM;
 157                         goto out;
 158                 }
 159         }
 160         rdev.name = requested_dev_name;
 161         tomoyo_fill_path_info(&rdev);
 162         r->param_type = TOMOYO_TYPE_MOUNT_ACL;
 163         r->param.mount.need_dev = need_dev;
 164         r->param.mount.dev = &rdev;
 165         r->param.mount.dir = &rdir;
 166         r->param.mount.type = &rtype;
 167         r->param.mount.flags = flags;
 168         do {
 169                 tomoyo_check_acl(r, tomoyo_check_mount_acl);
 170                 error = tomoyo_audit_mount_log(r);
 171         } while (error == TOMOYO_RETRY_REQUEST);
 172  out:
 173         kfree(requested_dev_name);
 174         kfree(requested_dir_name);
 175         if (fstype)
 176                 put_filesystem(fstype);
 177         kfree(requested_type);
 178         return error;
 179 }
 180
 181 /**
 182  * tomoyo_mount_permission - Check permission for mount() operation.
 183  *
 184  * @dev_name:  Name of device file.
 185  * @path:      Pointer to "struct path".
 186  * @type:      Name of filesystem type. May be NULL.
 187  * @flags:     Mount options.
 188  * @data_page: Optional data. May be NULL.
 189  *
 190  * Returns 0 on success, negative value otherwise.
 191  */
 192 int tomoyo_mount_permission(char *dev_name, struct path *path, char *type,
 193                             unsigned long flags, void *data_page)
 194 {
 195         struct tomoyo_request_info r;
 196         int error;
 197         int idx;
 198
 199         if (tomoyo_init_request_info(&r, NULL, TOMOYO_MAC_FILE_MOUNT)
 200             == TOMOYO_CONFIG_DISABLED)
 201                 return 0;
 202         if ((flags & MS_MGC_MSK) == MS_MGC_VAL)
 203                 flags &= ~MS_MGC_MSK;
 204         if (flags & MS_REMOUNT) {
 205                 type = TOMOYO_MOUNT_REMOUNT_KEYWORD;
 206                 flags &= ~MS_REMOUNT;
 207         }
 208         if (flags & MS_MOVE) {
 209                 type = TOMOYO_MOUNT_MOVE_KEYWORD;
 210                 flags &= ~MS_MOVE;
 211         }
 212         if (flags & MS_BIND) {
 213                 type = TOMOYO_MOUNT_BIND_KEYWORD;
 214                 flags &= ~MS_BIND;
 215         }
 216         if (flags & MS_UNBINDABLE) {
 217                 type = TOMOYO_MOUNT_MAKE_UNBINDABLE_KEYWORD;
 218                 flags &= ~MS_UNBINDABLE;
 219         }
 220         if (flags & MS_PRIVATE) {
 221                 type = TOMOYO_MOUNT_MAKE_PRIVATE_KEYWORD;
 222                 flags &= ~MS_PRIVATE;
 223         }
 224         if (flags & MS_SLAVE) {
 225                 type = TOMOYO_MOUNT_MAKE_SLAVE_KEYWORD;
 226                 flags &= ~MS_SLAVE;
 227         }
 228         if (flags & MS_SHARED) {
 229                 type = TOMOYO_MOUNT_MAKE_SHARED_KEYWORD;
 230                 flags &= ~MS_SHARED;
 231         }
 232         if (!type)
 233                 type = "<NULL>";
 234         idx = tomoyo_read_lock();
 235         error = tomoyo_mount_acl(&r, dev_name, path, type, flags);
 236         tomoyo_read_unlock(idx);
 237         return error;
 238 }
 239
 240 static bool tomoyo_same_mount_acl(const struct tomoyo_acl_info *a,
 241                                   const struct tomoyo_acl_info *b)
 242 {
 243         const struct tomoyo_mount_acl *p1 = container_of(a, typeof(*p1), head);
 244         const struct tomoyo_mount_acl *p2 = container_of(b, typeof(*p2), head);
 245         return tomoyo_same_acl_head(&p1->head, &p2->head) &&
 246                 tomoyo_same_name_union(&p1->dev_name, &p2->dev_name) &&
 247                 tomoyo_same_name_union(&p1->dir_name, &p2->dir_name) &&
 248                 tomoyo_same_name_union(&p1->fs_type, &p2->fs_type) &&
 249                 tomoyo_same_number_union(&p1->flags, &p2->flags);
 250 }
 251
 252 /**
 253  * tomoyo_write_mount - Write "struct tomoyo_mount_acl" list.
 254  *
 255  * @data:      String to parse.
 256  * @domain:    Pointer to "struct tomoyo_domain_info".
 257  * @is_delete: True if it is a delete request.
 258  *
 259  * Returns 0 on success, negative value otherwise.
 260  *
 261  * Caller holds tomoyo_read_lock().
 262  */
 263 int tomoyo_write_mount(char *data, struct tomoyo_domain_info *domain,
 264                        const bool is_delete)
 265 {
 266         struct tomoyo_mount_acl e = { .head.type = TOMOYO_TYPE_MOUNT_ACL };
 267         int error = is_delete ? -ENOENT : -ENOMEM;
 268         char *w[4];
 269         if (!tomoyo_tokenize(data, w, sizeof(w)) || !w[3][0])
 270                 return -EINVAL;
 271         if (!tomoyo_parse_name_union(w[0], &e.dev_name) ||
 272             !tomoyo_parse_name_union(w[1], &e.dir_name) ||
 273             !tomoyo_parse_name_union(w[2], &e.fs_type) ||
 274             !tomoyo_parse_number_union(w[3], &e.flags))
 275                 goto out;
 276         error = tomoyo_update_domain(&e.head, sizeof(e), is_delete, domain,
 277                                      tomoyo_same_mount_acl, NULL);
 278  out:
 279         tomoyo_put_name_union(&e.dev_name);
 280         tomoyo_put_name_union(&e.dir_name);
 281         tomoyo_put_name_union(&e.fs_type);
 282         tomoyo_put_number_union(&e.flags);
 283         return error;
 284 }