mount.c revision eadd99cc85347b4f9eb10122ac90032eb4971b02
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. */ 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. 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 path path; 79 struct file_system_type *fstype = NULL; 80 const char *requested_type = NULL; 81 const char *requested_dir_name = NULL; 82 const char *requested_dev_name = NULL; 83 struct tomoyo_path_info rtype; 84 struct tomoyo_path_info rdev; 85 struct tomoyo_path_info rdir; 86 int need_dev = 0; 87 int error = -ENOMEM; 88 89 /* Get fstype. */ 90 requested_type = tomoyo_encode(type); 91 if (!requested_type) 92 goto out; 93 rtype.name = requested_type; 94 tomoyo_fill_path_info(&rtype); 95 96 /* Get mount point. */ 97 requested_dir_name = tomoyo_realpath_from_path(dir); 98 if (!requested_dir_name) { 99 error = -ENOMEM; 100 goto out; 101 } 102 rdir.name = requested_dir_name; 103 tomoyo_fill_path_info(&rdir); 104 105 /* Compare fs name. */ 106 if (type == tomoyo_mounts[TOMOYO_MOUNT_REMOUNT]) { 107 /* dev_name is ignored. */ 108 } else if (type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_UNBINDABLE] || 109 type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_PRIVATE] || 110 type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_SLAVE] || 111 type == tomoyo_mounts[TOMOYO_MOUNT_MAKE_SHARED]) { 112 /* dev_name is ignored. */ 113 } else if (type == tomoyo_mounts[TOMOYO_MOUNT_BIND] || 114 type == tomoyo_mounts[TOMOYO_MOUNT_MOVE]) { 115 need_dev = -1; /* dev_name is a directory */ 116 } else { 117 fstype = get_fs_type(type); 118 if (!fstype) { 119 error = -ENODEV; 120 goto out; 121 } 122 if (fstype->fs_flags & FS_REQUIRES_DEV) 123 /* dev_name is a block device file. */ 124 need_dev = 1; 125 } 126 if (need_dev) { 127 /* Get mount point or device file. */ 128 if (kern_path(dev_name, LOOKUP_FOLLOW, &path)) { 129 error = -ENOENT; 130 goto out; 131 } 132 requested_dev_name = tomoyo_realpath_from_path(&path); 133 path_put(&path); 134 if (!requested_dev_name) { 135 error = -ENOENT; 136 goto out; 137 } 138 } else { 139 /* Map dev_name to "<NULL>" if no dev_name given. */ 140 if (!dev_name) 141 dev_name = "<NULL>"; 142 requested_dev_name = tomoyo_encode(dev_name); 143 if (!requested_dev_name) { 144 error = -ENOMEM; 145 goto out; 146 } 147 } 148 rdev.name = requested_dev_name; 149 tomoyo_fill_path_info(&rdev); 150 r->param_type = TOMOYO_TYPE_MOUNT_ACL; 151 r->param.mount.need_dev = need_dev; 152 r->param.mount.dev = &rdev; 153 r->param.mount.dir = &rdir; 154 r->param.mount.type = &rtype; 155 r->param.mount.flags = flags; 156 do { 157 tomoyo_check_acl(r, tomoyo_check_mount_acl); 158 error = tomoyo_audit_mount_log(r); 159 } while (error == TOMOYO_RETRY_REQUEST); 160 out: 161 kfree(requested_dev_name); 162 kfree(requested_dir_name); 163 if (fstype) 164 put_filesystem(fstype); 165 kfree(requested_type); 166 return error; 167} 168 169/** 170 * tomoyo_mount_permission - Check permission for mount() operation. 171 * 172 * @dev_name: Name of device file. 173 * @path: Pointer to "struct path". 174 * @type: Name of filesystem type. May be NULL. 175 * @flags: Mount options. 176 * @data_page: Optional data. May be NULL. 177 * 178 * Returns 0 on success, negative value otherwise. 179 */ 180int tomoyo_mount_permission(char *dev_name, struct path *path, 181 const char *type, unsigned long flags, 182 void *data_page) 183{ 184 struct tomoyo_request_info r; 185 int error; 186 int idx; 187 188 if (tomoyo_init_request_info(&r, NULL, TOMOYO_MAC_FILE_MOUNT) 189 == TOMOYO_CONFIG_DISABLED) 190 return 0; 191 if ((flags & MS_MGC_MSK) == MS_MGC_VAL) 192 flags &= ~MS_MGC_MSK; 193 if (flags & MS_REMOUNT) { 194 type = tomoyo_mounts[TOMOYO_MOUNT_REMOUNT]; 195 flags &= ~MS_REMOUNT; 196 } 197 if (flags & MS_MOVE) { 198 type = tomoyo_mounts[TOMOYO_MOUNT_MOVE]; 199 flags &= ~MS_MOVE; 200 } 201 if (flags & MS_BIND) { 202 type = tomoyo_mounts[TOMOYO_MOUNT_BIND]; 203 flags &= ~MS_BIND; 204 } 205 if (flags & MS_UNBINDABLE) { 206 type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_UNBINDABLE]; 207 flags &= ~MS_UNBINDABLE; 208 } 209 if (flags & MS_PRIVATE) { 210 type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_PRIVATE]; 211 flags &= ~MS_PRIVATE; 212 } 213 if (flags & MS_SLAVE) { 214 type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_SLAVE]; 215 flags &= ~MS_SLAVE; 216 } 217 if (flags & MS_SHARED) { 218 type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_SHARED]; 219 flags &= ~MS_SHARED; 220 } 221 if (!type) 222 type = "<NULL>"; 223 idx = tomoyo_read_lock(); 224 error = tomoyo_mount_acl(&r, dev_name, path, type, flags); 225 tomoyo_read_unlock(idx); 226 return error; 227} 228