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 /* String table for special mount operations. */
  11 static const char * const tomoyo_mounts[TOMOYO_MAX_SPECIAL_MOUNT] = {
  12         [TOMOYO_MOUNT_BIND]            = "--bind",
  13         [TOMOYO_MOUNT_MOVE]            = "--move",
  14         [TOMOYO_MOUNT_REMOUNT]         = "--remount",
  15         [TOMOYO_MOUNT_MAKE_UNBINDABLE] = "--make-unbindable",
  16         [TOMOYO_MOUNT_MAKE_PRIVATE]    = "--make-private",
  17         [TOMOYO_MOUNT_MAKE_SLAVE]      = "--make-slave",
  18         [TOMOYO_MOUNT_MAKE_SHARED]     = "--make-shared",
  19 };
  20
  21 /**
  22  * tomoyo_audit_mount_log - Audit mount log.
  23  *
  24  * @r: Pointer to "struct tomoyo_request_info".
  25  *
  26  * Returns 0 on success, negative value otherwise.
  27  */
  28 static int tomoyo_audit_mount_log(struct tomoyo_request_info *r)
  29 {
  30         const char *dev = r->param.mount.dev->name;
  31         const char *dir = r->param.mount.dir->name;
  32         const char *type = r->param.mount.type->name;
  33         const unsigned long flags = r->param.mount.flags;
  34         if (r->granted)
  35                 return 0;
  36         if (type == tomoyo_mounts[TOMOYO_MOUNT_REMOUNT])
  37                 tomoyo_warn_log(r, "mount -o remount %s 0x%lX", dir, flags);
  38         else if (type == tomoyo_mounts[TOMOYO_MOUNT_BIND]
  39                  || type == tomoyo_mounts[TOMOYO_MOUNT_MOVE])
  40                 tomoyo_warn_log(r, "mount %s %s %s 0x%lX", type, dev, dir,
  41                                 flags);
  42         else if (type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_UNBINDABLE] ||
  43                  type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_PRIVATE] ||
  44                  type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_SLAVE] ||
  45                  type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_SHARED])
  46                 tomoyo_warn_log(r, "mount %s %s 0x%lX", type, dir, flags);
  47         else
  48                 tomoyo_warn_log(r, "mount -t %s %s %s 0x%lX", type, dev, dir,
  49                                 flags);
  50         return tomoyo_supervisor(r, "allow_mount %s %s %s 0x%lX\n",
  51                                  r->param.mount.dev->name,
  52                                  r->param.mount.dir->name, type, flags);
  53 }
  54
  55 /**
  56  * tomoyo_check_mount_acl - Check permission for path path path number operation.
  57  *
  58  * @r:   Pointer to "struct tomoyo_request_info".
  59  * @ptr: Pointer to "struct tomoyo_acl_info".
  60  *
  61  * Returns true if granted, false otherwise.
  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,
  69                                            &acl->flags) &&
  70                 tomoyo_compare_name_union(r->param.mount.type,
  71                                           &acl->fs_type) &&
  72                 tomoyo_compare_name_union(r->param.mount.dir,
  73                                           &acl->dir_name) &&
  74                 (!r->param.mount.need_dev ||
  75                  tomoyo_compare_name_union(r->param.mount.dev,
  76                                            &acl->dev_name));
  77 }
  78
  79 /**
  80  * tomoyo_mount_acl - Check permission for mount() operation.
  81  *
  82  * @r:        Pointer to "struct tomoyo_request_info".
  83  * @dev_name: Name of device file.
  84  * @dir:      Pointer to "struct path".
  85  * @type:     Name of filesystem type.
  86  * @flags:    Mount options.
  87  *
  88  * Returns 0 on success, negative value otherwise.
  89  *
  90  * Caller holds tomoyo_read_lock().
  91  */
  92 static int tomoyo_mount_acl(struct tomoyo_request_info *r, char *dev_name,
  93                             struct path *dir, const char *type,
  94                             unsigned long flags)
  95 {
  96         struct path path;
  97         struct file_system_type *fstype = NULL;
  98         const char *requested_type = NULL;
  99         const char *requested_dir_name = NULL;
 100         const char *requested_dev_name = NULL;
 101         struct tomoyo_path_info rtype;
 102         struct tomoyo_path_info rdev;
 103         struct tomoyo_path_info rdir;
 104         int need_dev = 0;
 105         int error = -ENOMEM;
 106
 107         /* Get fstype. */
 108         requested_type = tomoyo_encode(type);
 109         if (!requested_type)
 110                 goto out;
 111         rtype.name = requested_type;
 112         tomoyo_fill_path_info(&rtype);
 113
 114         /* Get mount point. */
 115         requested_dir_name = tomoyo_realpath_from_path(dir);
 116         if (!requested_dir_name) {
 117                 error = -ENOMEM;
 118                 goto out;
 119         }
 120         rdir.name = requested_dir_name;
 121         tomoyo_fill_path_info(&rdir);
 122
 123         /* Compare fs name. */
 124         if (type == tomoyo_mounts[TOMOYO_MOUNT_REMOUNT]) {
 125                 /* dev_name is ignored. */
 126         } else if (type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_UNBINDABLE] ||
 127                    type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_PRIVATE] ||
 128                    type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_SLAVE] ||
 129                    type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_SHARED]) {
 130                 /* dev_name is ignored. */
 131         } else if (type == tomoyo_mounts[TOMOYO_MOUNT_BIND] ||
 132                    type == tomoyo_mounts[TOMOYO_MOUNT_MOVE]) {
 133                 need_dev = -1; /* dev_name is a directory */
 134         } else {
 135                 fstype = get_fs_type(type);
 136                 if (!fstype) {
 137                         error = -ENODEV;
 138                         goto out;
 139                 }
 140                 if (fstype->fs_flags & FS_REQUIRES_DEV)
 141                         /* dev_name is a block device file. */
 142                         need_dev = 1;
 143         }
 144         if (need_dev) {
 145                 /* Get mount point or device file. */
 146                 if (kern_path(dev_name, LOOKUP_FOLLOW, &path)) {
 147                         error = -ENOENT;
 148                         goto out;
 149                 }
 150                 requested_dev_name = tomoyo_realpath_from_path(&path);
 151                 path_put(&path);
 152                 if (!requested_dev_name) {
 153                         error = -ENOENT;
 154                         goto out;
 155                 }
 156         } else {
 157                 /* Map dev_name to "<NULL>" if no dev_name given. */
 158                 if (!dev_name)
 159                         dev_name = "<NULL>";
 160                 requested_dev_name = tomoyo_encode(dev_name);
 161                 if (!requested_dev_name) {
 162                         error = -ENOMEM;
 163                         goto out;
 164                 }
 165         }
 166         rdev.name = requested_dev_name;
 167         tomoyo_fill_path_info(&rdev);
 168         r->param_type = TOMOYO_TYPE_MOUNT_ACL;
 169         r->param.mount.need_dev = need_dev;
 170         r->param.mount.dev = &rdev;
 171         r->param.mount.dir = &rdir;
 172         r->param.mount.type = &rtype;
 173         r->param.mount.flags = flags;
 174         do {
 175                 tomoyo_check_acl(r, tomoyo_check_mount_acl);
 176                 error = tomoyo_audit_mount_log(r);
 177         } while (error == TOMOYO_RETRY_REQUEST);
 178  out:
 179         kfree(requested_dev_name);
 180         kfree(requested_dir_name);
 181         if (fstype)
 182                 put_filesystem(fstype);
 183         kfree(requested_type);
 184         return error;
 185 }
 186
 187 /**
 188  * tomoyo_mount_permission - Check permission for mount() operation.
 189  *
 190  * @dev_name:  Name of device file.
 191  * @path:      Pointer to "struct path".
 192  * @type:      Name of filesystem type. May be NULL.
 193  * @flags:     Mount options.
 194  * @data_page: Optional data. May be NULL.
 195  *
 196  * Returns 0 on success, negative value otherwise.
 197  */
 198 int tomoyo_mount_permission(char *dev_name, struct path *path,
 199                             const char *type, unsigned long flags,
 200                             void *data_page)
 201 {
 202         struct tomoyo_request_info r;
 203         int error;
 204         int idx;
 205
 206         if (tomoyo_init_request_info(&r, NULL, TOMOYO_MAC_FILE_MOUNT)
 207             == TOMOYO_CONFIG_DISABLED)
 208                 return 0;
 209         if ((flags & MS_MGC_MSK) == MS_MGC_VAL)
 210                 flags &= ~MS_MGC_MSK;
 211         if (flags & MS_REMOUNT) {
 212                 type = tomoyo_mounts[TOMOYO_MOUNT_REMOUNT];
 213                 flags &= ~MS_REMOUNT;
 214         }
 215         if (flags & MS_MOVE) {
 216                 type = tomoyo_mounts[TOMOYO_MOUNT_MOVE];
 217                 flags &= ~MS_MOVE;
 218         }
 219         if (flags & MS_BIND) {
 220                 type = tomoyo_mounts[TOMOYO_MOUNT_BIND];
 221                 flags &= ~MS_BIND;
 222         }
 223         if (flags & MS_UNBINDABLE) {
 224                 type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_UNBINDABLE];
 225                 flags &= ~MS_UNBINDABLE;
 226         }
 227         if (flags & MS_PRIVATE) {
 228                 type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_PRIVATE];
 229                 flags &= ~MS_PRIVATE;
 230         }
 231         if (flags & MS_SLAVE) {
 232                 type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_SLAVE];
 233                 flags &= ~MS_SLAVE;
 234         }
 235         if (flags & MS_SHARED) {
 236                 type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_SHARED];
 237                 flags &= ~MS_SHARED;
 238         }
 239         if (!type)
 240                 type = "<NULL>";
 241         idx = tomoyo_read_lock();
 242         error = tomoyo_mount_acl(&r, dev_name, path, type, flags);
 243         tomoyo_read_unlock(idx);
 244         return error;
 245 }