diff --git a/share/man/man5/fdescfs.5 b/share/man/man5/fdescfs.5 index 3f16104c0ac8..f2abda2bb4c2 100644 --- a/share/man/man5/fdescfs.5 +++ b/share/man/man5/fdescfs.5 @@ -1,140 +1,208 @@ +.\" Copyright (c) 2021 The FreeBSD Foundation, Inc. +.\" .\" Copyright (c) 1996 .\" Mike Pritchard . All rights reserved. .\" .\" Copyright (c) 1992, 1993, 1994 .\" The Regents of the University of California. All rights reserved. .\" All rights reserved. .\" .\" This code is derived from software donated to Berkeley by .\" Jan-Simon Pendry. .\" +.\" Parts of this documentation was written by +.\" Konstantin Belousov under sponsorship +.\" from the FreeBSD Foundation. +.\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" $FreeBSD$ .\" -.Dd August 1, 2017 +.Dd May 17, 2021 .Dt FDESCFS 5 .Os .Sh NAME .Nm fdescfs .Nd file-descriptor file system .Sh SYNOPSIS .Bd -literal fdescfs /dev/fd fdescfs rw 0 0 .Ed .Sh DESCRIPTION The file-descriptor file system, or .Nm , provides access to the per-process file descriptor namespace in the global file system namespace. The conventional mount point is .Pa /dev/fd . .Pp The file system's contents appear as a list of numbered files which correspond to the open files of the process reading the directory. The files .Pa /dev/fd/0 through .Pa /dev/fd/# refer to file descriptors which can be accessed through the file system. -If the file descriptor is open and the mode the file is being opened +.Pp +The following mount options can be used when mounting +.Nm +filesystem: +.Bl -tag -width linrdlnk +.It Cm nodup +For file descriptors referencing vnodes, instead of the +.Xr dup 2 +semantic described above, implement re-opening of the referenced vnode. +See below for more details. +.It Cm linrdlnk +Report the type of the +.Nm +vnode as +.Dv VLNK +instead of +.Fx +traditional +.Dv VCHR . +For +.Xr linux 4 +ABI compatibility mount +.Nm +volume with the +.Cm linrdlnk +option. +.El +.Pp +For +.Nm +mounted without the +.Cm nodup +mount option, +if the file descriptor is open and the mode the file is being opened with is a subset of the mode of the existing descriptor, the call: .Bd -literal -offset indent fd = open("/dev/fd/0", mode); .Ed .Pp and the call: .Bd -literal -offset indent fd = fcntl(0, F_DUPFD, 0); .Ed .Pp are equivalent. -.Pp Flags to the .Xr open 2 call other than .Dv O_RDONLY , .Dv O_WRONLY and .Dv O_RDWR are ignored. .Pp +For +.Nm +mounted with the +.Cm nodup +option, and file descriptor referencing a vnode, the call: +.Bd -literal -offset indent +fd = open("/dev/fd/0", mode); +.Ed +.Pp +reopens the referenced vnode with the specified +.Fa mode . +In other words, the +.Fn open +call above is equivalent to +.Bd -literal -offset indent +fd = openat(0, "", O_EMPTY_PATH, mode); +.Ed +.Pp +In particular, if the file descriptor was opened with the +.Dv O_PATH +flag, then either +.Dv O_EMPTY_PATH +or +.Fn open +over +.Nm +mount with +.Cm nodup +option allows one to convert it to a regularly opened file, +assuming that the current permissions allow the requested +.Fa mode . +.Pp .Em "Note:" .Pa /dev/fd/0 , .Pa /dev/fd/1 and .Pa /dev/fd/2 files are created by default when devfs alone is mounted. .Nm creates entries for all file descriptors opened by the process. -.Pp -For -.Xr linux 4 -ABI compatibility mount -.Nm -volume with -.Cm linrdlnk -option. .Sh FILES .Bl -tag -width /dev/stderr -compact .It Pa /dev/fd/# .El .Sh EXAMPLES To mount a .Nm volume located on .Pa /dev/fd : .Pp -.Dl "mount -t fdescfs null /dev/fd" +.Dl "mount -t fdescfs none /dev/fd" .Pp For .Xr linux 4 ABI compatibility: .Pp -.Dl "mount -t fdescfs -o linrdlnk null /compat/linux/dev/fd" +.Dl "mount -t fdescfs -o linrdlnk none /compat/linux/dev/fd" +.Pp +For substitute of +.Dv O_EMPTY_PATH +flag use: +.Pp +.Dl "mount -t fdescfs -o nodup none /dev/fdpath" .Sh SEE ALSO .Xr devfs 5 , .Xr mount 8 .Sh HISTORY The .Nm file system first appeared in .Bx 4.4 . The .Nm manual page first appeared in .Fx 2.2 . .Sh AUTHORS .An -nosplit The .Nm manual page was written by .An Mike Pritchard Aq Mt mpp@FreeBSD.org , and was based on the manual page written by .An Jan-Simon Pendry . diff --git a/sys/fs/fdescfs/fdesc.h b/sys/fs/fdescfs/fdesc.h index b578b7309130..94682f42cdb3 100644 --- a/sys/fs/fdescfs/fdesc.h +++ b/sys/fs/fdescfs/fdesc.h @@ -1,75 +1,76 @@ /*- * SPDX-License-Identifier: BSD-3-Clause * * Copyright (c) 1992, 1993 * The Regents of the University of California. All rights reserved. * * This code is derived from software donated to Berkeley by * Jan-Simon Pendry. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)fdesc.h 8.5 (Berkeley) 1/21/94 * * $FreeBSD$ */ #ifndef _FS_FDESC_H_ #define _FS_FDESC_H_ /* Private mount flags for fdescfs. */ #define FMNT_UNMOUNTF 0x01 #define FMNT_LINRDLNKF 0x02 +#define FMNT_NODUP 0x04 struct fdescmount { struct vnode *f_root; /* Root node */ int flags; }; #define FD_ROOT 1 #define FD_DESC 3 typedef enum { Froot, Fdesc } fdntype; struct fdescnode { LIST_ENTRY(fdescnode) fd_hash; /* Hash list */ struct vnode *fd_vnode; /* Back ptr to vnode */ fdntype fd_type; /* Type of this node */ unsigned fd_fd; /* Fd to be dup'ed */ int fd_ix; /* filesystem index */ }; extern struct mtx fdesc_hashmtx; #define VFSTOFDESC(mp) ((struct fdescmount *)((mp)->mnt_data)) #define VTOFDESC(vp) ((struct fdescnode *)(vp)->v_data) extern vfs_init_t fdesc_init; extern vfs_uninit_t fdesc_uninit; extern int fdesc_allocvp(fdntype, unsigned, int, struct mount *, struct vnode **); #endif /* !_FS_FDESC_H_ */ diff --git a/sys/fs/fdescfs/fdesc_vfsops.c b/sys/fs/fdescfs/fdesc_vfsops.c index 64f8d28bdcfd..9d8fdda47cbf 100644 --- a/sys/fs/fdescfs/fdesc_vfsops.c +++ b/sys/fs/fdescfs/fdesc_vfsops.c @@ -1,242 +1,244 @@ /*- * SPDX-License-Identifier: BSD-3-Clause * * Copyright (c) 1992, 1993, 1995 * The Regents of the University of California. All rights reserved. * * This code is derived from software donated to Berkeley by * Jan-Simon Pendry. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)fdesc_vfsops.c 8.4 (Berkeley) 1/21/94 * * $FreeBSD$ */ /* * /dev/fd Filesystem */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include static MALLOC_DEFINE(M_FDESCMNT, "fdesc_mount", "FDESC mount structure"); static vfs_cmount_t fdesc_cmount; static vfs_mount_t fdesc_mount; static vfs_unmount_t fdesc_unmount; static vfs_statfs_t fdesc_statfs; static vfs_root_t fdesc_root; /* * Compatibility shim for old mount(2) system call. */ int fdesc_cmount(struct mntarg *ma, void *data, uint64_t flags) { return kernel_mount(ma, flags); } /* * Mount the per-process file descriptors (/dev/fd) */ static int fdesc_mount(struct mount *mp) { struct fdescmount *fmp; struct vnode *rvp; int error; /* * Update is a no-op */ if (mp->mnt_flag & (MNT_UPDATE | MNT_ROOTFS)) return (EOPNOTSUPP); fmp = malloc(sizeof(struct fdescmount), M_FDESCMNT, M_WAITOK); /* XXX */ /* * We need to initialize a few bits of our local mount point struct to * avoid confusion in allocvp. */ mp->mnt_data = fmp; fmp->flags = 0; if (vfs_getopt(mp->mnt_optnew, "linrdlnk", NULL, NULL) == 0) fmp->flags |= FMNT_LINRDLNKF; + if (vfs_getopt(mp->mnt_optnew, "nodup", NULL, NULL) == 0) + fmp->flags |= FMNT_NODUP; error = fdesc_allocvp(Froot, -1, FD_ROOT, mp, &rvp); if (error) { free(fmp, M_FDESCMNT); mp->mnt_data = NULL; return (error); } VN_LOCK_ASHARE(rvp); rvp->v_type = VDIR; rvp->v_vflag |= VV_ROOT; fmp->f_root = rvp; VOP_UNLOCK(rvp); MNT_ILOCK(mp); /* XXX -- don't mark as local to work around fts() problems */ /*mp->mnt_flag |= MNT_LOCAL;*/ /* * Enable shared locking so that there is no contention on the root * vnode. Note only root vnode enables shared locking for itself, * so this end up being a nop for the rest. */ mp->mnt_kern_flag |= MNTK_LOOKUP_SHARED | MNTK_EXTENDED_SHARED; MNT_IUNLOCK(mp); vfs_getnewfsid(mp); vfs_mountedfrom(mp, "fdescfs"); return (0); } static int fdesc_unmount(struct mount *mp, int mntflags) { struct fdescmount *fmp; int error, flags; flags = 0; fmp = mp->mnt_data; if (mntflags & MNT_FORCE) { /* The hash mutex protects the private mount flags. */ mtx_lock(&fdesc_hashmtx); fmp->flags |= FMNT_UNMOUNTF; mtx_unlock(&fdesc_hashmtx); flags |= FORCECLOSE; } /* * Clear out buffer cache. I don't think we * ever get anything cached at this level at the * moment, but who knows... * * There is 1 extra root vnode reference corresponding * to f_root. */ if ((error = vflush(mp, 1, flags, curthread)) != 0) return (error); /* * Finally, throw away the fdescmount structure. */ mp->mnt_data = NULL; free(fmp, M_FDESCMNT); return (0); } static int fdesc_root(struct mount *mp, int flags, struct vnode **vpp) { struct vnode *vp; /* * Return locked reference to root. */ vp = VFSTOFDESC(mp)->f_root; vget(vp, flags | LK_RETRY); *vpp = vp; return (0); } static int fdesc_statfs(struct mount *mp, struct statfs *sbp) { struct thread *td; struct filedesc *fdp; int lim; int i; int last; int freefd; uint64_t limit; td = curthread; /* * Compute number of free file descriptors. * [ Strange results will ensue if the open file * limit is ever reduced below the current number * of open files... ] */ lim = lim_cur(td, RLIMIT_NOFILE); fdp = td->td_proc->p_fd; FILEDESC_SLOCK(fdp); limit = racct_get_limit(td->td_proc, RACCT_NOFILE); if (lim > limit) lim = limit; last = min(fdp->fd_nfiles, lim); freefd = 0; for (i = fdp->fd_freefile; i < last; i++) if (fdp->fd_ofiles[i].fde_file == NULL) freefd++; /* * Adjust for the fact that the fdesc array may not * have been fully allocated yet. */ if (fdp->fd_nfiles < lim) freefd += (lim - fdp->fd_nfiles); FILEDESC_SUNLOCK(fdp); sbp->f_flags = 0; sbp->f_bsize = DEV_BSIZE; sbp->f_iosize = DEV_BSIZE; sbp->f_blocks = 2; /* 1K to keep df happy */ sbp->f_bfree = 0; sbp->f_bavail = 0; sbp->f_files = lim + 1; /* Allow for "." */ sbp->f_ffree = freefd; /* See comments above */ return (0); } static struct vfsops fdesc_vfsops = { .vfs_cmount = fdesc_cmount, .vfs_init = fdesc_init, .vfs_mount = fdesc_mount, .vfs_root = fdesc_root, .vfs_statfs = fdesc_statfs, .vfs_uninit = fdesc_uninit, .vfs_unmount = fdesc_unmount, }; VFS_SET(fdesc_vfsops, fdescfs, VFCF_SYNTHETIC | VFCF_JAIL); diff --git a/sys/fs/fdescfs/fdesc_vnops.c b/sys/fs/fdescfs/fdesc_vnops.c index 1271b50e6e94..c5a7b86f1de5 100644 --- a/sys/fs/fdescfs/fdesc_vnops.c +++ b/sys/fs/fdescfs/fdesc_vnops.c @@ -1,660 +1,670 @@ /*- * SPDX-License-Identifier: BSD-3-Clause * * Copyright (c) 1992, 1993 * The Regents of the University of California. All rights reserved. * * This code is derived from software donated to Berkeley by * Jan-Simon Pendry. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)fdesc_vnops.c 8.9 (Berkeley) 1/21/94 * * $FreeBSD$ */ /* * /dev/fd Filesystem */ #include #include #include #include #include #include #include /* boottime */ #include #include #include #include /* Must come after sys/malloc.h */ #include #include #include #include #include #include #include #include #define NFDCACHE 4 #define FD_NHASH(ix) \ (&fdhashtbl[(ix) & fdhash]) static LIST_HEAD(fdhashhead, fdescnode) *fdhashtbl; static u_long fdhash; struct mtx fdesc_hashmtx; static vop_getattr_t fdesc_getattr; static vop_lookup_t fdesc_lookup; static vop_open_t fdesc_open; static vop_pathconf_t fdesc_pathconf; static vop_readdir_t fdesc_readdir; static vop_readlink_t fdesc_readlink; static vop_reclaim_t fdesc_reclaim; static vop_setattr_t fdesc_setattr; static struct vop_vector fdesc_vnodeops = { .vop_default = &default_vnodeops, .vop_access = VOP_NULL, .vop_getattr = fdesc_getattr, .vop_lookup = fdesc_lookup, .vop_open = fdesc_open, .vop_pathconf = fdesc_pathconf, .vop_readdir = fdesc_readdir, .vop_readlink = fdesc_readlink, .vop_reclaim = fdesc_reclaim, .vop_setattr = fdesc_setattr, }; VFS_VOP_VECTOR_REGISTER(fdesc_vnodeops); static void fdesc_insmntque_dtr(struct vnode *, void *); static void fdesc_remove_entry(struct fdescnode *); /* * Initialise cache headers */ int fdesc_init(struct vfsconf *vfsp) { mtx_init(&fdesc_hashmtx, "fdescfs_hash", NULL, MTX_DEF); fdhashtbl = hashinit(NFDCACHE, M_CACHE, &fdhash); return (0); } /* * Uninit ready for unload. */ int fdesc_uninit(struct vfsconf *vfsp) { hashdestroy(fdhashtbl, M_CACHE, fdhash); mtx_destroy(&fdesc_hashmtx); return (0); } /* * If allocating vnode fails, call this. */ static void fdesc_insmntque_dtr(struct vnode *vp, void *arg) { vgone(vp); vput(vp); } /* * Remove an entry from the hash if it exists. */ static void fdesc_remove_entry(struct fdescnode *fd) { struct fdhashhead *fc; struct fdescnode *fd2; fc = FD_NHASH(fd->fd_ix); mtx_lock(&fdesc_hashmtx); LIST_FOREACH(fd2, fc, fd_hash) { if (fd == fd2) { LIST_REMOVE(fd, fd_hash); break; } } mtx_unlock(&fdesc_hashmtx); } int fdesc_allocvp(fdntype ftype, unsigned fd_fd, int ix, struct mount *mp, struct vnode **vpp) { struct fdescmount *fmp; struct fdhashhead *fc; struct fdescnode *fd, *fd2; struct vnode *vp, *vp2; struct thread *td; int error; td = curthread; fc = FD_NHASH(ix); loop: mtx_lock(&fdesc_hashmtx); /* * If a forced unmount is progressing, we need to drop it. The flags are * protected by the hashmtx. */ fmp = mp->mnt_data; if (fmp == NULL || fmp->flags & FMNT_UNMOUNTF) { mtx_unlock(&fdesc_hashmtx); return (-1); } LIST_FOREACH(fd, fc, fd_hash) { if (fd->fd_ix == ix && fd->fd_vnode->v_mount == mp) { /* Get reference to vnode in case it's being free'd */ vp = fd->fd_vnode; VI_LOCK(vp); mtx_unlock(&fdesc_hashmtx); if (vget(vp, LK_EXCLUSIVE | LK_INTERLOCK)) goto loop; *vpp = vp; return (0); } } mtx_unlock(&fdesc_hashmtx); fd = malloc(sizeof(struct fdescnode), M_TEMP, M_WAITOK); error = getnewvnode("fdescfs", mp, &fdesc_vnodeops, &vp); if (error) { free(fd, M_TEMP); return (error); } vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); vp->v_data = fd; fd->fd_vnode = vp; fd->fd_type = ftype; fd->fd_fd = fd_fd; fd->fd_ix = ix; if (ftype == Fdesc && fmp->flags & FMNT_LINRDLNKF) vp->v_vflag |= VV_READLINK; error = insmntque1(vp, mp, fdesc_insmntque_dtr, NULL); if (error != 0) { *vpp = NULLVP; return (error); } /* Make sure that someone didn't beat us when inserting the vnode. */ mtx_lock(&fdesc_hashmtx); /* * If a forced unmount is progressing, we need to drop it. The flags are * protected by the hashmtx. */ fmp = mp->mnt_data; if (fmp == NULL || fmp->flags & FMNT_UNMOUNTF) { mtx_unlock(&fdesc_hashmtx); vgone(vp); vput(vp); *vpp = NULLVP; return (-1); } LIST_FOREACH(fd2, fc, fd_hash) { if (fd2->fd_ix == ix && fd2->fd_vnode->v_mount == mp) { /* Get reference to vnode in case it's being free'd */ vp2 = fd2->fd_vnode; VI_LOCK(vp2); mtx_unlock(&fdesc_hashmtx); error = vget(vp2, LK_EXCLUSIVE | LK_INTERLOCK); /* Someone beat us, dec use count and wait for reclaim */ vgone(vp); vput(vp); /* If we didn't get it, return no vnode. */ if (error) vp2 = NULLVP; *vpp = vp2; return (error); } } /* If we came here, we can insert it safely. */ LIST_INSERT_HEAD(fc, fd, fd_hash); mtx_unlock(&fdesc_hashmtx); *vpp = vp; return (0); } struct fdesc_get_ino_args { fdntype ftype; unsigned fd_fd; int ix; struct file *fp; struct thread *td; }; static int fdesc_get_ino_alloc(struct mount *mp, void *arg, int lkflags, struct vnode **rvp) { struct fdesc_get_ino_args *a; + struct fdescmount *fdm; + struct vnode *vp; int error; a = arg; - error = fdesc_allocvp(a->ftype, a->fd_fd, a->ix, mp, rvp); + fdm = VFSTOFDESC(mp); + if ((fdm->flags & FMNT_NODUP) != 0 && a->fp->f_type == DTYPE_VNODE) { + vp = a->fp->f_vnode; + vget(vp, lkflags | LK_RETRY); + *rvp = vp; + error = 0; + } else { + error = fdesc_allocvp(a->ftype, a->fd_fd, a->ix, mp, rvp); + } fdrop(a->fp, a->td); return (error); } /* * vp is the current namei directory * ndp is the name to locate in that directory... */ static int fdesc_lookup(struct vop_lookup_args *ap) { struct vnode **vpp = ap->a_vpp; struct vnode *dvp = ap->a_dvp; struct componentname *cnp = ap->a_cnp; char *pname = cnp->cn_nameptr; struct thread *td = cnp->cn_thread; struct file *fp; struct fdesc_get_ino_args arg; int nlen = cnp->cn_namelen; u_int fd, fd1; int error; struct vnode *fvp; if ((cnp->cn_flags & ISLASTCN) && (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { error = EROFS; goto bad; } if (cnp->cn_namelen == 1 && *pname == '.') { *vpp = dvp; VREF(dvp); return (0); } if (VTOFDESC(dvp)->fd_type != Froot) { error = ENOTDIR; goto bad; } fd = 0; /* the only time a leading 0 is acceptable is if it's "0" */ if (*pname == '0' && nlen != 1) { error = ENOENT; goto bad; } while (nlen--) { if (*pname < '0' || *pname > '9') { error = ENOENT; goto bad; } fd1 = 10 * fd + *pname++ - '0'; if (fd1 < fd) { error = ENOENT; goto bad; } fd = fd1; } /* * No rights to check since 'fp' isn't actually used. */ if ((error = fget(td, fd, &cap_no_rights, &fp)) != 0) goto bad; /* Check if we're looking up ourselves. */ if (VTOFDESC(dvp)->fd_ix == FD_DESC + fd) { /* * In case we're holding the last reference to the file, the dvp * will be re-acquired. */ vhold(dvp); VOP_UNLOCK(dvp); fdrop(fp, td); /* Re-aquire the lock afterwards. */ vn_lock(dvp, LK_RETRY | LK_EXCLUSIVE); vdrop(dvp); fvp = dvp; if (VN_IS_DOOMED(dvp)) error = ENOENT; } else { /* * Unlock our root node (dvp) when doing this, since we might * deadlock since the vnode might be locked by another thread * and the root vnode lock will be obtained afterwards (in case * we're looking up the fd of the root vnode), which will be the * opposite lock order. Vhold the root vnode first so we don't * lose it. */ arg.ftype = Fdesc; arg.fd_fd = fd; arg.ix = FD_DESC + fd; arg.fp = fp; arg.td = td; error = vn_vget_ino_gen(dvp, fdesc_get_ino_alloc, &arg, LK_EXCLUSIVE, &fvp); } if (error) goto bad; *vpp = fvp; return (0); bad: *vpp = NULL; return (error); } static int fdesc_open(struct vop_open_args *ap) { struct vnode *vp = ap->a_vp; if (VTOFDESC(vp)->fd_type == Froot) return (0); /* * XXX Kludge: set td->td_proc->p_dupfd to contain the value of the file * descriptor being sought for duplication. The error return ensures * that the vnode for this device will be released by vn_open. Open * will detect this special error and take the actions in dupfdopen. * Other callers of vn_open or VOP_OPEN will simply report the * error. */ ap->a_td->td_dupfd = VTOFDESC(vp)->fd_fd; /* XXX */ return (ENODEV); } static int fdesc_pathconf(struct vop_pathconf_args *ap) { struct vnode *vp = ap->a_vp; int error; switch (ap->a_name) { case _PC_NAME_MAX: *ap->a_retval = NAME_MAX; return (0); case _PC_LINK_MAX: if (VTOFDESC(vp)->fd_type == Froot) *ap->a_retval = 2; else *ap->a_retval = 1; return (0); default: if (VTOFDESC(vp)->fd_type == Froot) return (vop_stdpathconf(ap)); vref(vp); VOP_UNLOCK(vp); error = kern_fpathconf(curthread, VTOFDESC(vp)->fd_fd, ap->a_name, ap->a_retval); vn_lock(vp, LK_SHARED | LK_RETRY); vunref(vp); return (error); } } static int fdesc_getattr(struct vop_getattr_args *ap) { struct vnode *vp = ap->a_vp; struct vattr *vap = ap->a_vap; struct timeval boottime; getboottime(&boottime); vap->va_mode = S_IRUSR|S_IXUSR|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH; vap->va_fileid = VTOFDESC(vp)->fd_ix; vap->va_uid = 0; vap->va_gid = 0; vap->va_blocksize = DEV_BSIZE; vap->va_atime.tv_sec = boottime.tv_sec; vap->va_atime.tv_nsec = 0; vap->va_mtime = vap->va_atime; vap->va_ctime = vap->va_mtime; vap->va_gen = 0; vap->va_flags = 0; vap->va_bytes = 0; vap->va_filerev = 0; switch (VTOFDESC(vp)->fd_type) { case Froot: vap->va_type = VDIR; vap->va_nlink = 2; vap->va_size = DEV_BSIZE; vap->va_rdev = NODEV; break; case Fdesc: vap->va_type = (vp->v_vflag & VV_READLINK) == 0 ? VCHR : VLNK; vap->va_nlink = 1; vap->va_size = 0; vap->va_rdev = makedev(0, vap->va_fileid); break; default: panic("fdesc_getattr"); break; } vp->v_type = vap->va_type; return (0); } static int fdesc_setattr(struct vop_setattr_args *ap) { struct vattr *vap = ap->a_vap; struct vnode *vp; struct mount *mp; struct file *fp; struct thread *td = curthread; cap_rights_t rights; unsigned fd; int error; /* * Can't mess with the root vnode */ if (VTOFDESC(ap->a_vp)->fd_type == Froot) return (EACCES); fd = VTOFDESC(ap->a_vp)->fd_fd; /* * Allow setattr where there is an underlying vnode. */ error = getvnode(td, fd, cap_rights_init_one(&rights, CAP_EXTATTR_SET), &fp); if (error) { /* * getvnode() returns EINVAL if the file descriptor is not * backed by a vnode. Silently drop all changes except * chflags(2) in this case. */ if (error == EINVAL) { if (vap->va_flags != VNOVAL) error = EOPNOTSUPP; else error = 0; } return (error); } vp = fp->f_vnode; if ((error = vn_start_write(vp, &mp, V_WAIT | PCATCH)) == 0) { vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); error = VOP_SETATTR(vp, ap->a_vap, ap->a_cred); VOP_UNLOCK(vp); vn_finished_write(mp); } fdrop(fp, td); return (error); } #define UIO_MX _GENERIC_DIRLEN(10) /* number of symbols in INT_MAX printout */ static int fdesc_readdir(struct vop_readdir_args *ap) { struct fdescmount *fmp; struct uio *uio = ap->a_uio; struct filedesc *fdp; struct dirent d; struct dirent *dp = &d; int error, i, off, fcnt; if (VTOFDESC(ap->a_vp)->fd_type != Froot) panic("fdesc_readdir: not dir"); fmp = VFSTOFDESC(ap->a_vp->v_mount); if (ap->a_ncookies != NULL) *ap->a_ncookies = 0; off = (int)uio->uio_offset; if (off != uio->uio_offset || off < 0 || (u_int)off % UIO_MX != 0 || uio->uio_resid < UIO_MX) return (EINVAL); i = (u_int)off / UIO_MX; fdp = uio->uio_td->td_proc->p_fd; error = 0; fcnt = i - 2; /* The first two nodes are `.' and `..' */ FILEDESC_SLOCK(fdp); while (i < fdp->fd_nfiles + 2 && uio->uio_resid >= UIO_MX) { bzero((caddr_t)dp, UIO_MX); switch (i) { case 0: /* `.' */ case 1: /* `..' */ dp->d_fileno = i + FD_ROOT; dp->d_namlen = i + 1; dp->d_reclen = UIO_MX; bcopy("..", dp->d_name, dp->d_namlen); dp->d_type = DT_DIR; dirent_terminate(dp); break; default: if (fdp->fd_ofiles[fcnt].fde_file == NULL) break; dp->d_namlen = sprintf(dp->d_name, "%d", fcnt); dp->d_reclen = UIO_MX; dp->d_type = (fmp->flags & FMNT_LINRDLNKF) == 0 ? DT_CHR : DT_LNK; dp->d_fileno = i + FD_DESC; dirent_terminate(dp); break; } /* NOTE: d_off is the offset of the *next* entry. */ dp->d_off = UIO_MX * (i + 1); if (dp->d_namlen != 0) { /* * And ship to userland */ FILEDESC_SUNLOCK(fdp); error = uiomove(dp, UIO_MX, uio); if (error) goto done; FILEDESC_SLOCK(fdp); } i++; fcnt++; } FILEDESC_SUNLOCK(fdp); done: uio->uio_offset = i * UIO_MX; return (error); } static int fdesc_reclaim(struct vop_reclaim_args *ap) { struct vnode *vp; struct fdescnode *fd; vp = ap->a_vp; fd = VTOFDESC(vp); fdesc_remove_entry(fd); free(vp->v_data, M_TEMP); vp->v_data = NULL; return (0); } static int fdesc_readlink(struct vop_readlink_args *va) { struct vnode *vp, *vn; struct thread *td; struct uio *uio; struct file *fp; char *freepath, *fullpath; size_t pathlen; int lockflags, fd_fd; int error; freepath = NULL; vn = va->a_vp; if (VTOFDESC(vn)->fd_type != Fdesc) panic("fdesc_readlink: not fdescfs link"); fd_fd = ((struct fdescnode *)vn->v_data)->fd_fd; lockflags = VOP_ISLOCKED(vn); VOP_UNLOCK(vn); td = curthread; error = fget_cap(td, fd_fd, &cap_no_rights, &fp, NULL); if (error != 0) goto out; switch (fp->f_type) { case DTYPE_VNODE: vp = fp->f_vnode; error = vn_fullpath(vp, &fullpath, &freepath); break; default: fullpath = "anon_inode:[unknown]"; break; } if (error == 0) { uio = va->a_uio; pathlen = strlen(fullpath); error = uiomove(fullpath, pathlen, uio); } if (freepath != NULL) free(freepath, M_TEMP); fdrop(fp, td); out: vn_lock(vn, lockflags | LK_RETRY); return (error); }