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, char *dev_name,
  75                            struct path *dir, const char *type,
  76                            unsigned long flags)
  77{
  78        struct tomoyo_obj_info obj = { };
  79        struct path path;
  80        struct file_system_type *fstype = NULL;
  81        const char *requested_type = NULL;
  82        const char *requested_dir_name = NULL;
  83        const char *requested_dev_name = NULL;
  84        struct tomoyo_path_info rtype;
  85        struct tomoyo_path_info rdev;
  86        struct tomoyo_path_info rdir;
  87        int need_dev = 0;
  88        int error = -ENOMEM;
  89        r->obj = &obj;
  90
  91        /* Get fstype. */
  92        requested_type = tomoyo_encode(type);
  93        if (!requested_type)
  94                goto out;
  95        rtype.name = requested_type;
  96        tomoyo_fill_path_info(&rtype);
  97
  98        /* Get mount point. */
  99        obj.path2 = *dir;
 100        requested_dir_name = tomoyo_realpath_from_path(dir);
 101        if (!requested_dir_name) {
 102                error = -ENOMEM;
 103                goto out;
 104        }
 105        rdir.name = requested_dir_name;
 106        tomoyo_fill_path_info(&rdir);
 107
 108        /* Compare fs name. */
 109        if (type == tomoyo_mounts[TOMOYO_MOUNT_REMOUNT]) {
 110                /* dev_name is ignored. */
 111        } else if (type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_UNBINDABLE] ||
 112                   type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_PRIVATE] ||
 113                   type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_SLAVE] ||
 114                   type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_SHARED]) {
 115                /* dev_name is ignored. */
 116        } else if (type == tomoyo_mounts[TOMOYO_MOUNT_BIND] ||
 117                   type == tomoyo_mounts[TOMOYO_MOUNT_MOVE]) {
 118                need_dev = -1; /* dev_name is a directory */
 119        } else {
 120                fstype = get_fs_type(type);
 121                if (!fstype) {
 122                        error = -ENODEV;
 123                        goto out;
 124                }
 125                if (fstype->fs_flags & FS_REQUIRES_DEV)
 126                        /* dev_name is a block device file. */
 127                        need_dev = 1;
 128        }
 129        if (need_dev) {
 130                /* Get mount point or device file. */
 131                if (!dev_name || kern_path(dev_name, LOOKUP_FOLLOW, &path)) {
 132                        error = -ENOENT;
 133                        goto out;
 134                }
 135                obj.path1 = path;
 136                requested_dev_name = tomoyo_realpath_from_path(&path);
 137                if (!requested_dev_name) {
 138                        error = -ENOENT;
 139                        goto out;
 140                }
 141        } else {
 142                /* Map dev_name to "<NULL>" if no dev_name given. */
 143                if (!dev_name)
 144                        dev_name = "<NULL>";
 145                requested_dev_name = tomoyo_encode(dev_name);
 146                if (!requested_dev_name) {
 147                        error = -ENOMEM;
 148                        goto out;
 149                }
 150        }
 151        rdev.name = requested_dev_name;
 152        tomoyo_fill_path_info(&rdev);
 153        r->param_type = TOMOYO_TYPE_MOUNT_ACL;
 154        r->param.mount.need_dev = need_dev;
 155        r->param.mount.dev = &rdev;
 156        r->param.mount.dir = &rdir;
 157        r->param.mount.type = &rtype;
 158        r->param.mount.flags = flags;
 159        do {
 160                tomoyo_check_acl(r, tomoyo_check_mount_acl);
 161                error = tomoyo_audit_mount_log(r);
 162        } while (error == TOMOYO_RETRY_REQUEST);
 163 out:
 164        kfree(requested_dev_name);
 165        kfree(requested_dir_name);
 166        if (fstype)
 167                put_filesystem(fstype);
 168        kfree(requested_type);
 169        /* Drop refcount obtained by kern_path(). */
 170        if (obj.path1.dentry)
 171                path_put(&obj.path1);
 172        return error;
 173}
 174
 175/**
 176 * tomoyo_mount_permission - Check permission for mount() operation.
 177 *
 178 * @dev_name:  Name of device file. Maybe NULL.
 179 * @path:      Pointer to "struct path".
 180 * @type:      Name of filesystem type. Maybe NULL.
 181 * @flags:     Mount options.
 182 * @data_page: Optional data. Maybe NULL.
 183 *
 184 * Returns 0 on success, negative value otherwise.
 185 */
 186int tomoyo_mount_permission(char *dev_name, struct path *path,
 187                            const char *type, unsigned long flags,
 188                            void *data_page)
 189{
 190        struct tomoyo_request_info r;
 191        int error;
 192        int idx;
 193
 194        if (tomoyo_init_request_info(&r, NULL, TOMOYO_MAC_FILE_MOUNT)
 195            == TOMOYO_CONFIG_DISABLED)
 196                return 0;
 197        if ((flags & MS_MGC_MSK) == MS_MGC_VAL)
 198                flags &= ~MS_MGC_MSK;
 199        if (flags & MS_REMOUNT) {
 200                type = tomoyo_mounts[TOMOYO_MOUNT_REMOUNT];
 201                flags &= ~MS_REMOUNT;
 202        } else if (flags & MS_BIND) {
 203                type = tomoyo_mounts[TOMOYO_MOUNT_BIND];
 204                flags &= ~MS_BIND;
 205        } else if (flags & MS_SHARED) {
 206                if (flags & (MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE))
 207                        return -EINVAL;
 208                type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_SHARED];
 209                flags &= ~MS_SHARED;
 210        } else if (flags & MS_PRIVATE) {
 211                if (flags & (MS_SHARED | MS_SLAVE | MS_UNBINDABLE))
 212                        return -EINVAL;
 213                type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_PRIVATE];
 214                flags &= ~MS_PRIVATE;
 215        } else if (flags & MS_SLAVE) {
 216                if (flags & (MS_SHARED | MS_PRIVATE | MS_UNBINDABLE))
 217                        return -EINVAL;
 218                type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_SLAVE];
 219                flags &= ~MS_SLAVE;
 220        } else if (flags & MS_UNBINDABLE) {
 221                if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE))
 222                        return -EINVAL;
 223                type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_UNBINDABLE];
 224                flags &= ~MS_UNBINDABLE;
 225        } else if (flags & MS_MOVE) {
 226                type = tomoyo_mounts[TOMOYO_MOUNT_MOVE];
 227                flags &= ~MS_MOVE;
 228        }
 229        if (!type)
 230                type = "<NULL>";
 231        idx = tomoyo_read_lock();
 232        error = tomoyo_mount_acl(&r, dev_name, path, type, flags);
 233        tomoyo_read_unlock(idx);
 234        return error;
 235}
 236
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