1 /* $NetBSD: vfs_hooks.c,v 1.9 2024/12/07 02:27:38 riastradh Exp $ */ 2 3 /*- 4 * Copyright (c) 2005 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Julio M. Merino Vidal. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 /* 33 * VFS hooks. 34 */ 35 36 #include <sys/cdefs.h> 37 __KERNEL_RCSID(0, "$NetBSD: vfs_hooks.c,v 1.9 2024/12/07 02:27:38 riastradh Exp $"); 38 39 #include <sys/param.h> 40 41 #include <sys/errno.h> 42 #include <sys/mount.h> 43 #include <sys/mutex.h> 44 #include <sys/queue.h> 45 #include <sys/sdt.h> 46 47 LIST_HEAD(vfs_hooks_head, vfs_hooks) vfs_hooks_head = 48 LIST_HEAD_INITIALIZER(vfs_hooks_head); 49 50 kmutex_t vfs_hooks_lock; 51 52 void 53 vfs_hooks_init(void) 54 { 55 56 mutex_init(&vfs_hooks_lock, MUTEX_DEFAULT, IPL_NONE); 57 } 58 59 int 60 vfs_hooks_attach(struct vfs_hooks *vfs_hooks) 61 { 62 63 mutex_enter(&vfs_hooks_lock); 64 LIST_INSERT_HEAD(&vfs_hooks_head, vfs_hooks, vfs_hooks_list); 65 mutex_exit(&vfs_hooks_lock); 66 67 return 0; 68 } 69 70 int 71 vfs_hooks_detach(struct vfs_hooks *vfs_hooks) 72 { 73 struct vfs_hooks *hp; 74 int ret = 0; 75 76 mutex_enter(&vfs_hooks_lock); 77 LIST_FOREACH(hp, &vfs_hooks_head, vfs_hooks_list) { 78 if (hp == vfs_hooks) { 79 LIST_REMOVE(hp, vfs_hooks_list); 80 break; 81 } 82 } 83 if (hp == NULL) 84 ret = SET_ERROR(ESRCH); 85 mutex_exit(&vfs_hooks_lock); 86 87 return ret; 88 } 89 90 /* 91 * Macro to be used in one of the vfs_hooks_* function for hooks that 92 * return an error code. Calls will stop as soon as one of the hooks 93 * fails. 94 */ 95 #define VFS_HOOKS_W_ERROR(func, fargs, hook, hargs) \ 96 int \ 97 func fargs \ 98 { \ 99 int error; \ 100 struct vfs_hooks *hp; \ 101 \ 102 error = EJUSTRETURN; \ 103 \ 104 mutex_enter(&vfs_hooks_lock); \ 105 LIST_FOREACH(hp, &vfs_hooks_head, vfs_hooks_list) { \ 106 if (hp-> hook != NULL) { \ 107 error = hp-> hook hargs; \ 108 if (error != 0) \ 109 break; \ 110 } \ 111 } \ 112 mutex_exit(&vfs_hooks_lock); \ 113 \ 114 return error; \ 115 } 116 117 /* 118 * Macro to be used in one of the vfs_hooks_* function for hooks that 119 * do not return any error code. All hooks will be executed 120 * unconditionally. 121 */ 122 #define VFS_HOOKS_WO_ERROR(func, fargs, hook, hargs) \ 123 void \ 124 func fargs \ 125 { \ 126 struct vfs_hooks *hp; \ 127 \ 128 mutex_enter(&vfs_hooks_lock); \ 129 LIST_FOREACH(hp, &vfs_hooks_head, vfs_hooks_list) { \ 130 if (hp-> hook != NULL) \ 131 hp-> hook hargs; \ 132 } \ 133 mutex_exit(&vfs_hooks_lock); \ 134 } 135 136 /* 137 * Routines to iterate over VFS hooks lists and execute them. 138 */ 139 140 VFS_HOOKS_WO_ERROR(vfs_hooks_unmount, (struct mount *mp), vh_unmount, (mp)); 141 VFS_HOOKS_W_ERROR(vfs_hooks_reexport, (struct mount *mp, const char *path, void *data), vh_reexport, (mp, path, data)); 142