1/*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 2007-2009 Google Inc. and Amit Singh 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions are 9 * met: 10 * 11 * * Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * * Redistributions in binary form must reproduce the above 14 * copyright notice, this list of conditions and the following disclaimer 15 * in the documentation and/or other materials provided with the 16 * distribution. 17 * * Neither the name of Google Inc. nor the names of its 18 * contributors may be used to endorse or promote products derived from 19 * this software without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 22 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 24 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 25 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 26 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 27 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 31 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 32 * 33 * Copyright (C) 2005 Csaba Henk. 34 * All rights reserved. 35 * 36 * Copyright (c) 2019 The FreeBSD Foundation 37 * 38 * Portions of this software were developed by BFF Storage Systems, LLC under 39 * sponsorship from the FreeBSD Foundation. 40 * 41 * Redistribution and use in source and binary forms, with or without 42 * modification, are permitted provided that the following conditions 43 * are met: 44 * 1. Redistributions of source code must retain the above copyright 45 * notice, this list of conditions and the following disclaimer. 46 * 2. Redistributions in binary form must reproduce the above copyright 47 * notice, this list of conditions and the following disclaimer in the 48 * documentation and/or other materials provided with the distribution. 49 * 50 * THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND 51 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 52 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 53 * ARE DISCLAIMED. IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE 54 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 55 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 56 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 57 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 58 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 59 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 60 * SUCH DAMAGE. 61 * 62 * $FreeBSD$ 63 */ 64 65#ifndef _FUSE_FILE_H_ 66#define _FUSE_FILE_H_ 67 68#include <sys/types.h> 69#include <sys/fcntl.h> 70#include <sys/stat.h> 71#include <sys/mman.h> 72#include <sys/vnode.h> 73 74/* 75 * The fufh type is the access mode of the fuse file handle. It's the portion 76 * of the open(2) flags related to permission. 77 */ 78typedef enum fufh_type { 79 FUFH_INVALID = -1, 80 FUFH_RDONLY = O_RDONLY, 81 FUFH_WRONLY = O_WRONLY, 82 FUFH_RDWR = O_RDWR, 83 FUFH_EXEC = O_EXEC, 84} fufh_type_t; 85 86/* 87 * FUSE File Handles 88 * 89 * The FUSE protocol says that a server may assign a unique 64-bit file handle 90 * every time that a file is opened. Effectively, that's once for each file 91 * descriptor. 92 * 93 * Unfortunately, the VFS doesn't help us here. VOPs don't have a 94 * struct file* argument. fileops do, but many syscalls bypass the fileops 95 * layer and go straight to a vnode. Some, like writing from cache, can't 96 * track a file handle even in theory. The entire concept of the file handle 97 * is a product of FUSE's Linux origins; Linux lacks vnodes and almost every 98 * file system operation takes a struct file* argument. 99 * 100 * Since FreeBSD's VFS is more file descriptor-agnostic, we must store FUSE 101 * filehandles in the vnode. One option would be to only store a single file 102 * handle and never open FUSE files concurrently. That's what NetBSD does. 103 * But that violates FUSE's security model. FUSE expects the server to do all 104 * authorization (except when mounted with -o default_permissions). In order 105 * to do that, the server needs us to send FUSE_OPEN every time somebody opens 106 * a new file descriptor. 107 * 108 * Another option would be to never open FUSE files concurrently, but send a 109 * FUSE_ACCESS prior to every open after the first. That would give the server 110 * the opportunity to authorize the access. Unfortunately, the FUSE protocol 111 * makes ACCESS optional. File systems that don't implement it are assumed to 112 * authorize everything. A survey of 32 fuse file systems showed that only 14 113 * implemented access. Among the laggards were a few that really ought to be 114 * doing server-side authorization. 115 * 116 * So we do something hacky, similar to what OpenBSD, Illumos, and OSXFuse do. 117 * we store a list of file handles, one for each combination of vnode, uid, 118 * gid, pid, and access mode. When opening a file, we first check whether 119 * there's already a matching file handle. If so, we reuse it. If not, we 120 * send FUSE_OPEN and create a new file handle. That minimizes the number of 121 * open file handles while still allowing the server to authorize stuff. 122 * 123 * VOPs that need a file handle search through the list for a close match. 124 * They can't be guaranteed of finding an exact match because, for example, a 125 * process may have changed its UID since opening the file. Also, most VOPs 126 * don't know exactly what permission they need. Is O_RDWR required or is 127 * O_RDONLY good enough? So the file handle we end up using may not be exactly 128 * the one we're supposed to use with that file descriptor. But if the FUSE 129 * file system isn't too picky, it will work. (FWIW even Linux sometimes 130 * guesses the file handle, during writes from cache or most SETATTR 131 * operations). 132 * 133 * I suspect this mess is part of the reason why neither NFS nor 9P have an 134 * equivalent of FUSE file handles. 135 */ 136struct fuse_filehandle { 137 LIST_ENTRY(fuse_filehandle) next; 138 139 /* The filehandle returned by FUSE_OPEN */ 140 uint64_t fh_id; 141 142 /* 143 * flags returned by FUSE_OPEN 144 * Supported flags: FOPEN_DIRECT_IO, FOPEN_KEEP_CACHE 145 * Unsupported: 146 * FOPEN_NONSEEKABLE: Adding support would require a new per-file 147 * or per-vnode attribute, which would have to be checked by 148 * kern_lseek (and others) for every file system. The benefit is 149 * dubious, since I'm unaware of any file systems in ports that use 150 * this flag. 151 */ 152 uint32_t fuse_open_flags; 153 154 /* The access mode of the file handle */ 155 fufh_type_t fufh_type; 156 157 /* Credentials used to open the file */ 158 gid_t gid; 159 pid_t pid; 160 uid_t uid; 161}; 162 163#define FUFH_IS_VALID(f) ((f)->fufh_type != FUFH_INVALID) 164 165/* 166 * Get the flags to use for FUSE_CREATE, FUSE_OPEN and FUSE_RELEASE 167 * 168 * These are supposed to be the same as the flags argument to open(2). 169 * However, since we can't reliably associate a fuse_filehandle with a specific 170 * file descriptor it would would be dangerous to include anything more than 171 * the access mode flags. For example, suppose we open a file twice, once with 172 * O_APPEND and once without. Then the user pwrite(2)s to offset using the 173 * second file descriptor. If fusefs uses the first file handle, then the 174 * server may append the write to the end of the file rather than at offset 0. 175 * To prevent problems like this, we only ever send the portion of flags 176 * related to access mode. 177 * 178 * It's essential to send that portion, because FUSE uses it for server-side 179 * authorization. 180 */ 181static inline int 182fufh_type_2_fflags(fufh_type_t type) 183{ 184 int oflags = -1; 185 186 switch (type) { 187 case FUFH_RDONLY: 188 case FUFH_WRONLY: 189 case FUFH_RDWR: 190 case FUFH_EXEC: 191 oflags = type; 192 break; 193 default: 194 break; 195 } 196 197 return oflags; 198} 199 200bool fuse_filehandle_validrw(struct vnode *vp, int mode, 201 struct ucred *cred, pid_t pid); 202int fuse_filehandle_get(struct vnode *vp, int fflag, 203 struct fuse_filehandle **fufhp, struct ucred *cred, 204 pid_t pid); 205int fuse_filehandle_get_anyflags(struct vnode *vp, 206 struct fuse_filehandle **fufhp, struct ucred *cred, 207 pid_t pid); 208int fuse_filehandle_getrw(struct vnode *vp, int fflag, 209 struct fuse_filehandle **fufhp, struct ucred *cred, 210 pid_t pid); 211 212void fuse_filehandle_init(struct vnode *vp, fufh_type_t fufh_type, 213 struct fuse_filehandle **fufhp, struct thread *td, 214 struct ucred *cred, struct fuse_open_out *foo); 215int fuse_filehandle_open(struct vnode *vp, int mode, 216 struct fuse_filehandle **fufhp, struct thread *td, 217 struct ucred *cred); 218int fuse_filehandle_close(struct vnode *vp, struct fuse_filehandle *fufh, 219 struct thread *td, struct ucred *cred); 220 221void fuse_file_init(void); 222void fuse_file_destroy(void); 223 224#endif /* _FUSE_FILE_H_ */ 225