1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1992, 1993, 1995 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software donated to Berkeley by 8 * Jan-Simon Pendry. 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 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * @(#)fdesc_vfsops.c 8.4 (Berkeley) 1/21/94 35 * 36 * $FreeBSD$ 37 */ 38 39 /* 40 * /dev/fd Filesystem 41 */ 42 43 #include <sys/param.h> 44 #include <sys/systm.h> 45 #include <sys/filedesc.h> 46 #include <sys/kernel.h> 47 #include <sys/jail.h> 48 #include <sys/lock.h> 49 #include <sys/mutex.h> 50 #include <sys/malloc.h> 51 #include <sys/mount.h> 52 #include <sys/proc.h> 53 #include <sys/racct.h> 54 #include <sys/resourcevar.h> 55 #include <sys/vnode.h> 56 57 #include <fs/fdescfs/fdesc.h> 58 59 static MALLOC_DEFINE(M_FDESCMNT, "fdesc_mount", "FDESC mount structure"); 60 61 static vfs_cmount_t fdesc_cmount; 62 static vfs_mount_t fdesc_mount; 63 static vfs_unmount_t fdesc_unmount; 64 static vfs_statfs_t fdesc_statfs; 65 static vfs_root_t fdesc_root; 66 67 /* 68 * Compatibility shim for old mount(2) system call. 69 */ 70 int 71 fdesc_cmount(struct mntarg *ma, void *data, uint64_t flags) 72 { 73 74 return kernel_mount(ma, flags); 75 } 76 77 /* 78 * Mount the per-process file descriptors (/dev/fd) 79 */ 80 static int 81 fdesc_mount(struct mount *mp) 82 { 83 struct fdescmount *fmp; 84 struct thread *td = curthread; 85 struct vnode *rvp; 86 int error; 87 88 if (!prison_allow(td->td_ucred, PR_ALLOW_MOUNT_FDESCFS)) 89 return (EPERM); 90 91 /* 92 * Update is a no-op 93 */ 94 if (mp->mnt_flag & (MNT_UPDATE | MNT_ROOTFS)) 95 return (EOPNOTSUPP); 96 97 fmp = malloc(sizeof(struct fdescmount), 98 M_FDESCMNT, M_WAITOK); /* XXX */ 99 100 /* 101 * We need to initialize a few bits of our local mount point struct to 102 * avoid confusion in allocvp. 103 */ 104 mp->mnt_data = fmp; 105 fmp->flags = 0; 106 if (vfs_getopt(mp->mnt_optnew, "linrdlnk", NULL, NULL) == 0) 107 fmp->flags |= FMNT_LINRDLNKF; 108 error = fdesc_allocvp(Froot, -1, FD_ROOT, mp, &rvp); 109 if (error) { 110 free(fmp, M_FDESCMNT); 111 mp->mnt_data = NULL; 112 return (error); 113 } 114 rvp->v_type = VDIR; 115 rvp->v_vflag |= VV_ROOT; 116 fmp->f_root = rvp; 117 VOP_UNLOCK(rvp, 0); 118 /* XXX -- don't mark as local to work around fts() problems */ 119 /*mp->mnt_flag |= MNT_LOCAL;*/ 120 vfs_getnewfsid(mp); 121 122 vfs_mountedfrom(mp, "fdescfs"); 123 return (0); 124 } 125 126 static int 127 fdesc_unmount(struct mount *mp, int mntflags) 128 { 129 struct fdescmount *fmp; 130 int error, flags; 131 132 flags = 0; 133 fmp = mp->mnt_data; 134 if (mntflags & MNT_FORCE) { 135 /* The hash mutex protects the private mount flags. */ 136 mtx_lock(&fdesc_hashmtx); 137 fmp->flags |= FMNT_UNMOUNTF; 138 mtx_unlock(&fdesc_hashmtx); 139 flags |= FORCECLOSE; 140 } 141 142 /* 143 * Clear out buffer cache. I don't think we 144 * ever get anything cached at this level at the 145 * moment, but who knows... 146 * 147 * There is 1 extra root vnode reference corresponding 148 * to f_root. 149 */ 150 if ((error = vflush(mp, 1, flags, curthread)) != 0) 151 return (error); 152 153 /* 154 * Finally, throw away the fdescmount structure. 155 */ 156 mp->mnt_data = NULL; 157 free(fmp, M_FDESCMNT); 158 return (0); 159 } 160 161 static int 162 fdesc_root(struct mount *mp, int flags, struct vnode **vpp) 163 { 164 struct vnode *vp; 165 166 /* 167 * Return locked reference to root. 168 */ 169 vp = VFSTOFDESC(mp)->f_root; 170 vget(vp, LK_EXCLUSIVE | LK_RETRY, curthread); 171 *vpp = vp; 172 return (0); 173 } 174 175 static int 176 fdesc_statfs(struct mount *mp, struct statfs *sbp) 177 { 178 struct thread *td; 179 struct filedesc *fdp; 180 int lim; 181 int i; 182 int last; 183 int freefd; 184 uint64_t limit; 185 186 td = curthread; 187 188 /* 189 * Compute number of free file descriptors. 190 * [ Strange results will ensue if the open file 191 * limit is ever reduced below the current number 192 * of open files... ] 193 */ 194 lim = lim_cur(td, RLIMIT_NOFILE); 195 fdp = td->td_proc->p_fd; 196 FILEDESC_SLOCK(fdp); 197 limit = racct_get_limit(td->td_proc, RACCT_NOFILE); 198 if (lim > limit) 199 lim = limit; 200 last = min(fdp->fd_nfiles, lim); 201 freefd = 0; 202 for (i = fdp->fd_freefile; i < last; i++) 203 if (fdp->fd_ofiles[i].fde_file == NULL) 204 freefd++; 205 206 /* 207 * Adjust for the fact that the fdesc array may not 208 * have been fully allocated yet. 209 */ 210 if (fdp->fd_nfiles < lim) 211 freefd += (lim - fdp->fd_nfiles); 212 FILEDESC_SUNLOCK(fdp); 213 214 sbp->f_flags = 0; 215 sbp->f_bsize = DEV_BSIZE; 216 sbp->f_iosize = DEV_BSIZE; 217 sbp->f_blocks = 2; /* 1K to keep df happy */ 218 sbp->f_bfree = 0; 219 sbp->f_bavail = 0; 220 sbp->f_files = lim + 1; /* Allow for "." */ 221 sbp->f_ffree = freefd; /* See comments above */ 222 return (0); 223 } 224 225 static struct vfsops fdesc_vfsops = { 226 .vfs_cmount = fdesc_cmount, 227 .vfs_init = fdesc_init, 228 .vfs_mount = fdesc_mount, 229 .vfs_root = fdesc_root, 230 .vfs_statfs = fdesc_statfs, 231 .vfs_uninit = fdesc_uninit, 232 .vfs_unmount = fdesc_unmount, 233 }; 234 235 VFS_SET(fdesc_vfsops, fdescfs, VFCF_SYNTHETIC | VFCF_JAIL); 236