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 35 /* 36 * /dev/fd Filesystem 37 */ 38 39 #include <sys/param.h> 40 #include <sys/systm.h> 41 #include <sys/filedesc.h> 42 #include <sys/kernel.h> 43 #include <sys/jail.h> 44 #include <sys/lock.h> 45 #include <sys/mutex.h> 46 #include <sys/malloc.h> 47 #include <sys/mount.h> 48 #include <sys/proc.h> 49 #include <sys/racct.h> 50 #include <sys/resourcevar.h> 51 #include <sys/vnode.h> 52 53 #include <fs/fdescfs/fdesc.h> 54 55 static MALLOC_DEFINE(M_FDESCMNT, "fdesc_mount", "FDESC mount structure"); 56 57 static vfs_cmount_t fdesc_cmount; 58 static vfs_mount_t fdesc_mount; 59 static vfs_unmount_t fdesc_unmount; 60 static vfs_statfs_t fdesc_statfs; 61 static vfs_root_t fdesc_root; 62 63 /* 64 * Compatibility shim for old mount(2) system call. 65 */ 66 int 67 fdesc_cmount(struct mntarg *ma, void *data, uint64_t flags) 68 { 69 70 return kernel_mount(ma, flags); 71 } 72 73 /* 74 * Mount the per-process file descriptors (/dev/fd) 75 */ 76 static int 77 fdesc_mount(struct mount *mp) 78 { 79 struct fdescmount *fmp; 80 struct vnode *rvp; 81 int error; 82 83 /* 84 * Update is a no-op 85 */ 86 if (mp->mnt_flag & (MNT_UPDATE | MNT_ROOTFS)) 87 return (EOPNOTSUPP); 88 89 fmp = malloc(sizeof(struct fdescmount), M_FDESCMNT, M_WAITOK); 90 91 /* 92 * We need to initialize a few bits of our local mount point struct to 93 * avoid confusion in allocvp. 94 */ 95 mp->mnt_data = fmp; 96 fmp->flags = 0; 97 if (vfs_getopt(mp->mnt_optnew, "linrdlnk", NULL, NULL) == 0) 98 fmp->flags |= FMNT_LINRDLNKF; 99 if (vfs_getopt(mp->mnt_optnew, "rdlnk", NULL, NULL) == 0) 100 fmp->flags |= FMNT_RDLNKF; 101 if (vfs_getopt(mp->mnt_optnew, "nodup", NULL, NULL) == 0) 102 fmp->flags |= FMNT_NODUP; 103 error = fdesc_allocvp(Froot, -1, FD_ROOT, mp, &rvp); 104 if (error) { 105 free(fmp, M_FDESCMNT); 106 mp->mnt_data = NULL; 107 return (error); 108 } 109 VN_LOCK_ASHARE(rvp); 110 rvp->v_type = VDIR; 111 rvp->v_vflag |= VV_ROOT; 112 fmp->f_root = rvp; 113 VOP_UNLOCK(rvp); 114 115 MNT_ILOCK(mp); 116 /* XXX -- don't mark as local to work around fts() problems */ 117 /*mp->mnt_flag |= MNT_LOCAL;*/ 118 /* 119 * Enable shared locking so that there is no contention on the root 120 * vnode. Note only root vnode enables shared locking for itself, 121 * so this end up being a nop for the rest. 122 */ 123 mp->mnt_kern_flag |= MNTK_LOOKUP_SHARED | MNTK_EXTENDED_SHARED; 124 MNT_IUNLOCK(mp); 125 126 vfs_getnewfsid(mp); 127 128 vfs_mountedfrom(mp, "fdescfs"); 129 return (0); 130 } 131 132 static int 133 fdesc_unmount(struct mount *mp, int mntflags) 134 { 135 struct fdescmount *fmp; 136 int error, flags; 137 138 flags = 0; 139 fmp = mp->mnt_data; 140 if (mntflags & MNT_FORCE) { 141 /* The hash mutex protects the private mount flags. */ 142 mtx_lock(&fdesc_hashmtx); 143 fmp->flags |= FMNT_UNMOUNTF; 144 mtx_unlock(&fdesc_hashmtx); 145 flags |= FORCECLOSE; 146 } 147 148 /* 149 * Clear out buffer cache. I don't think we 150 * ever get anything cached at this level at the 151 * moment, but who knows... 152 * 153 * There is 1 extra root vnode reference corresponding 154 * to f_root. 155 */ 156 if ((error = vflush(mp, 1, flags, curthread)) != 0) 157 return (error); 158 159 /* 160 * Finally, throw away the fdescmount structure. 161 */ 162 mp->mnt_data = NULL; 163 free(fmp, M_FDESCMNT); 164 return (0); 165 } 166 167 static int 168 fdesc_root(struct mount *mp, int flags, struct vnode **vpp) 169 { 170 struct vnode *vp; 171 172 /* 173 * Return locked reference to root. 174 */ 175 vp = VFSTOFDESC(mp)->f_root; 176 vget(vp, flags | LK_RETRY); 177 *vpp = vp; 178 return (0); 179 } 180 181 static int 182 fdesc_statfs(struct mount *mp, struct statfs *sbp) 183 { 184 struct thread *td; 185 struct filedesc *fdp; 186 int lim; 187 int i; 188 int last; 189 int freefd; 190 uint64_t limit; 191 192 td = curthread; 193 194 /* 195 * Compute number of free file descriptors. 196 * [ Strange results will ensue if the open file 197 * limit is ever reduced below the current number 198 * of open files... ] 199 */ 200 lim = lim_cur(td, RLIMIT_NOFILE); 201 fdp = td->td_proc->p_fd; 202 FILEDESC_SLOCK(fdp); 203 limit = racct_get_limit(td->td_proc, RACCT_NOFILE); 204 if (lim > limit) 205 lim = limit; 206 last = min(fdp->fd_nfiles, lim); 207 freefd = 0; 208 for (i = fdp->fd_freefile; i < last; i++) 209 if (fdp->fd_ofiles[i].fde_file == NULL) 210 freefd++; 211 212 /* 213 * Adjust for the fact that the fdesc array may not 214 * have been fully allocated yet. 215 */ 216 if (fdp->fd_nfiles < lim) 217 freefd += (lim - fdp->fd_nfiles); 218 FILEDESC_SUNLOCK(fdp); 219 220 sbp->f_flags = mp->mnt_flag & MNT_IGNORE; 221 sbp->f_bsize = DEV_BSIZE; 222 sbp->f_iosize = DEV_BSIZE; 223 sbp->f_blocks = 2; /* 1K to keep df happy */ 224 sbp->f_bfree = 2; 225 sbp->f_bavail = 2; 226 sbp->f_files = lim + 1; /* Allow for "." */ 227 sbp->f_ffree = freefd; /* See comments above */ 228 return (0); 229 } 230 231 static struct vfsops fdesc_vfsops = { 232 .vfs_cmount = fdesc_cmount, 233 .vfs_init = fdesc_init, 234 .vfs_mount = fdesc_mount, 235 .vfs_root = fdesc_root, 236 .vfs_statfs = fdesc_statfs, 237 .vfs_uninit = fdesc_uninit, 238 .vfs_unmount = fdesc_unmount, 239 }; 240 241 VFS_SET(fdesc_vfsops, fdescfs, VFCF_SYNTHETIC | VFCF_JAIL); 242