linux/security/tomoyo/mount.c
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   1/*
   2 * security/tomoyo/mount.c
   3 *
   4 * Copyright (C) 2005-2011  NTT DATA CORPORATION
   5 */
   6
   7#include <linux/slab.h>
   8#include "common.h"
   9
  10/* String table for special mount operations. */
  11static 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 */
  28static int tomoyo_audit_mount_log(struct tomoyo_request_info *r)
  29{
  30        return tomoyo_supervisor(r, "file mount %s %s %s 0x%lX\n",
  31                                 r->param.mount.dev->name,
  32                                 r->param.mount.dir->name,
  33                                 r->param.mount.type->name,
  34                                 r->param.mount.flags);
  35}
  36
  37/**
  38 * tomoyo_check_mount_acl - Check permission for path path path number operation.
  39 *
  40 * @r:   Pointer to "struct tomoyo_request_info".
  41 * @ptr: Pointer to "struct tomoyo_acl_info".
  42 *
  43 * Returns true if granted, false otherwise.
  44 */
  45static bool tomoyo_check_mount_acl(struct tomoyo_request_info *r,
  46                                   const struct tomoyo_acl_info *ptr)
  47{
  48        const struct tomoyo_mount_acl *acl =
  49                container_of(ptr, typeof(*acl), head);
  50        return tomoyo_compare_number_union(r->param.mount.flags,
  51                                           &acl->flags) &&
  52                tomoyo_compare_name_union(r->param.mount.type,
  53                                          &acl->fs_type) &&
  54                tomoyo_compare_name_union(r->param.mount.dir,
  55                                          &acl->dir_name) &&
  56                (!r->param.mount.need_dev ||
  57                 tomoyo_compare_name_union(r->param.mount.dev,
  58                                           &acl->dev_name));
  59}
  60
  61/**
  62 * tomoyo_mount_acl - Check permission for mount() operation.
  63 *
  64 * @r:        Pointer to "struct tomoyo_request_info".
  65 * @dev_name: Name of device file. Maybe NULL.
  66 * @dir:      Pointer to "struct path".
  67 * @type:     Name of filesystem type.
  68 * @flags:    Mount options.
  69 *
  70 * Returns 0 on success, negative value otherwise.
  71 *
  72 * Caller holds tomoyo_read_lock().
  73 */
  74static int tomoyo_mount_acl(struct tomoyo_request_info *r,
  75                            const char *dev_name,
  76                            struct path *dir, const char *type,
  77                            unsigned long flags)
  78{
  79        struct tomoyo_obj_info obj = { };
  80        struct path path;
  81        struct file_system_type *fstype = NULL;
  82        const char *requested_type = NULL;
  83        const char *requested_dir_name = NULL;
  84        const char *requested_dev_name = NULL;
  85        struct tomoyo_path_info rtype;
  86        struct tomoyo_path_info rdev;
  87        struct tomoyo_path_info rdir;
  88        int need_dev = 0;
  89        int error = -ENOMEM;
  90        r->obj = &obj;
  91
  92        /* Get fstype. */
  93        requested_type = tomoyo_encode(type);
  94        if (!requested_type)
  95                goto out;
  96        rtype.name = requested_type;
  97        tomoyo_fill_path_info(&rtype);
  98
  99        /* Get mount point. */
 100        obj.path2 = *dir;
 101        requested_dir_name = tomoyo_realpath_from_path(dir);
 102        if (!requested_dir_name) {
 103                error = -ENOMEM;
 104                goto out;
 105        }
 106        rdir.name = requested_dir_name;
 107        tomoyo_fill_path_info(&rdir);
 108
 109        /* Compare fs name. */
 110        if (type == tomoyo_mounts[TOMOYO_MOUNT_REMOUNT]) {
 111                /* dev_name is ignored. */
 112        } else if (type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_UNBINDABLE] ||
 113                   type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_PRIVATE] ||
 114                   type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_SLAVE] ||
 115                   type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_SHARED]) {
 116                /* dev_name is ignored. */
 117        } else if (type == tomoyo_mounts[TOMOYO_MOUNT_BIND] ||
 118                   type == tomoyo_mounts[TOMOYO_MOUNT_MOVE]) {
 119                need_dev = -1; /* dev_name is a directory */
 120        } else {
 121                fstype = get_fs_type(type);
 122                if (!fstype) {
 123                        error = -ENODEV;
 124                        goto out;
 125                }
 126                if (fstype->fs_flags & FS_REQUIRES_DEV)
 127                        /* dev_name is a block device file. */
 128                        need_dev = 1;
 129        }
 130        if (need_dev) {
 131                /* Get mount point or device file. */
 132                if (!dev_name || kern_path(dev_name, LOOKUP_FOLLOW, &path)) {
 133                        error = -ENOENT;
 134                        goto out;
 135                }
 136                obj.path1 = path;
 137                requested_dev_name = tomoyo_realpath_from_path(&path);
 138                if (!requested_dev_name) {
 139                        error = -ENOENT;
 140                        goto out;
 141                }
 142        } else {
 143                /* Map dev_name to "<NULL>" if no dev_name given. */
 144                if (!dev_name)
 145                        dev_name = "<NULL>";
 146                requested_dev_name = tomoyo_encode(dev_name);
 147                if (!requested_dev_name) {
 148                        error = -ENOMEM;
 149                        goto out;
 150                }
 151        }
 152        rdev.name = requested_dev_name;
 153        tomoyo_fill_path_info(&rdev);
 154        r->param_type = TOMOYO_TYPE_MOUNT_ACL;
 155        r->param.mount.need_dev = need_dev;
 156        r->param.mount.dev = &rdev;
 157        r->param.mount.dir = &rdir;
 158        r->param.mount.type = &rtype;
 159        r->param.mount.flags = flags;
 160        do {
 161                tomoyo_check_acl(r, tomoyo_check_mount_acl);
 162                error = tomoyo_audit_mount_log(r);
 163        } while (error == TOMOYO_RETRY_REQUEST);
 164 out:
 165        kfree(requested_dev_name);
 166        kfree(requested_dir_name);
 167        if (fstype)
 168                put_filesystem(fstype);
 169        kfree(requested_type);
 170        /* Drop refcount obtained by kern_path(). */
 171        if (obj.path1.dentry)
 172                path_put(&obj.path1);
 173        return error;
 174}
 175
 176/**
 177 * tomoyo_mount_permission - Check permission for mount() operation.
 178 *
 179 * @dev_name:  Name of device file. Maybe NULL.
 180 * @path:      Pointer to "struct path".
 181 * @type:      Name of filesystem type. Maybe NULL.
 182 * @flags:     Mount options.
 183 * @data_page: Optional data. Maybe NULL.
 184 *
 185 * Returns 0 on success, negative value otherwise.
 186 */
 187int tomoyo_mount_permission(const char *dev_name, struct path *path,
 188                            const char *type, unsigned long flags,
 189                            void *data_page)
 190{
 191        struct tomoyo_request_info r;
 192        int error;
 193        int idx;
 194
 195        if (tomoyo_init_request_info(&r, NULL, TOMOYO_MAC_FILE_MOUNT)
 196            == TOMOYO_CONFIG_DISABLED)
 197                return 0;
 198        if ((flags & MS_MGC_MSK) == MS_MGC_VAL)
 199                flags &= ~MS_MGC_MSK;
 200        if (flags & MS_REMOUNT) {
 201                type = tomoyo_mounts[TOMOYO_MOUNT_REMOUNT];
 202                flags &= ~MS_REMOUNT;
 203        } else if (flags & MS_BIND) {
 204                type = tomoyo_mounts[TOMOYO_MOUNT_BIND];
 205                flags &= ~MS_BIND;
 206        } else if (flags & MS_SHARED) {
 207                if (flags & (MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE))
 208                        return -EINVAL;
 209                type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_SHARED];
 210                flags &= ~MS_SHARED;
 211        } else if (flags & MS_PRIVATE) {
 212                if (flags & (MS_SHARED | MS_SLAVE | MS_UNBINDABLE))
 213                        return -EINVAL;
 214                type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_PRIVATE];
 215                flags &= ~MS_PRIVATE;
 216        } else if (flags & MS_SLAVE) {
 217                if (flags & (MS_SHARED | MS_PRIVATE | MS_UNBINDABLE))
 218                        return -EINVAL;
 219                type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_SLAVE];
 220                flags &= ~MS_SLAVE;
 221        } else if (flags & MS_UNBINDABLE) {
 222                if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE))
 223                        return -EINVAL;
 224                type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_UNBINDABLE];
 225                flags &= ~MS_UNBINDABLE;
 226        } else if (flags & MS_MOVE) {
 227                type = tomoyo_mounts[TOMOYO_MOUNT_MOVE];
 228                flags &= ~MS_MOVE;
 229        }
 230        if (!type)
 231                type = "<NULL>";
 232        idx = tomoyo_read_lock();
 233        error = tomoyo_mount_acl(&r, dev_name, path, type, flags);
 234        tomoyo_read_unlock(idx);
 235        return error;
 236}
 237
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