mount.c revision df91e49477a9be15921cb2854e1d12a3bdb5e425
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