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fdesc.h
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fdesc_vfsops.c
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fdesc_vnops.c
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Editing: fdesc_vnops.c
/*- * 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 <sys/param.h> #include <sys/systm.h> #include <sys/capsicum.h> #include <sys/conf.h> #include <sys/dirent.h> #include <sys/filedesc.h> #include <sys/kernel.h> /* boottime */ #include <sys/lock.h> #include <sys/mutex.h> #include <sys/malloc.h> #include <sys/file.h> /* Must come after sys/malloc.h */ #include <sys/mount.h> #include <sys/namei.h> #include <sys/proc.h> #include <sys/stat.h> #include <sys/syscallsubr.h> #include <sys/unistd.h> #include <sys/vnode.h> #include <fs/fdescfs/fdesc.h> #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; int error; a = arg; 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); }
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