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      1 /*	$NetBSD: ptyfs_vnops.c,v 1.69 2022/08/05 10:36:02 riastradh Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1993, 1995
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * This code is derived from software contributed 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  *	@(#)procfs_vnops.c	8.18 (Berkeley) 5/21/95
     35  */
     36 
     37 /*
     38  * Copyright (c) 1993 Jan-Simon Pendry
     39  *
     40  * This code is derived from software contributed to Berkeley by
     41  * Jan-Simon Pendry.
     42  *
     43  * Redistribution and use in source and binary forms, with or without
     44  * modification, are permitted provided that the following conditions
     45  * are met:
     46  * 1. Redistributions of source code must retain the above copyright
     47  *    notice, this list of conditions and the following disclaimer.
     48  * 2. Redistributions in binary form must reproduce the above copyright
     49  *    notice, this list of conditions and the following disclaimer in the
     50  *    documentation and/or other materials provided with the distribution.
     51  * 3. All advertising materials mentioning features or use of this software
     52  *    must display the following acknowledgement:
     53  *	This product includes software developed by the University of
     54  *	California, Berkeley and its contributors.
     55  * 4. Neither the name of the University nor the names of its contributors
     56  *    may be used to endorse or promote products derived from this software
     57  *    without specific prior written permission.
     58  *
     59  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     60  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     61  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     62  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     63  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     64  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     65  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     66  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     67  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     68  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     69  * SUCH DAMAGE.
     70  *
     71  *	@(#)procfs_vnops.c	8.18 (Berkeley) 5/21/95
     72  */
     73 
     74 /*
     75  * ptyfs vnode interface
     76  */
     77 
     78 #include <sys/cdefs.h>
     79 __KERNEL_RCSID(0, "$NetBSD: ptyfs_vnops.c,v 1.69 2022/08/05 10:36:02 riastradh Exp $");
     80 
     81 #include <sys/param.h>
     82 #include <sys/systm.h>
     83 #include <sys/time.h>
     84 #include <sys/kernel.h>
     85 #include <sys/file.h>
     86 #include <sys/filedesc.h>
     87 #include <sys/proc.h>
     88 #include <sys/vnode.h>
     89 #include <sys/namei.h>
     90 #include <sys/malloc.h>
     91 #include <sys/mount.h>
     92 #include <sys/select.h>
     93 #include <sys/dirent.h>
     94 #include <sys/resourcevar.h>
     95 #include <sys/stat.h>
     96 #include <sys/conf.h>
     97 #include <sys/tty.h>
     98 #include <sys/pty.h>
     99 #include <sys/kauth.h>
    100 
    101 #include <uvm/uvm_extern.h>	/* for PAGE_SIZE */
    102 
    103 #include <machine/reg.h>
    104 
    105 #include <fs/ptyfs/ptyfs.h>
    106 #include <miscfs/genfs/genfs.h>
    107 #include <miscfs/specfs/specdev.h>
    108 
    109 MALLOC_DECLARE(M_PTYFSTMP);
    110 
    111 /*
    112  * Vnode Operations.
    113  *
    114  */
    115 
    116 int	ptyfs_lookup	(void *);
    117 int	ptyfs_open	(void *);
    118 int	ptyfs_close	(void *);
    119 int	ptyfs_access	(void *);
    120 int	ptyfs_getattr	(void *);
    121 int	ptyfs_setattr	(void *);
    122 int	ptyfs_read	(void *);
    123 int	ptyfs_write	(void *);
    124 int	ptyfs_ioctl	(void *);
    125 int	ptyfs_poll	(void *);
    126 int	ptyfs_kqfilter	(void *);
    127 int	ptyfs_readdir	(void *);
    128 int	ptyfs_reclaim	(void *);
    129 int	ptyfs_inactive	(void *);
    130 int	ptyfs_print	(void *);
    131 int	ptyfs_pathconf	(void *);
    132 int	ptyfs_advlock	(void *);
    133 
    134 static int ptyfs_update(struct vnode *, const struct timespec *,
    135     const struct timespec *, int);
    136 static int ptyfs_chown(struct vnode *, uid_t, gid_t, kauth_cred_t,
    137     struct lwp *);
    138 static int ptyfs_chmod(struct vnode *, mode_t, kauth_cred_t, struct lwp *);
    139 static int atoi(const char *, size_t);
    140 
    141 /*
    142  * ptyfs vnode operations.
    143  */
    144 int (**ptyfs_vnodeop_p)(void *);
    145 const struct vnodeopv_entry_desc ptyfs_vnodeop_entries[] = {
    146 	{ &vop_default_desc, vn_default_error },
    147 	{ &vop_parsepath_desc, genfs_parsepath },	/* parsepath */
    148 	{ &vop_lookup_desc, ptyfs_lookup },		/* lookup */
    149 	{ &vop_create_desc, genfs_eopnotsupp },		/* create */
    150 	{ &vop_mknod_desc, genfs_eopnotsupp },		/* mknod */
    151 	{ &vop_open_desc, ptyfs_open },			/* open */
    152 	{ &vop_close_desc, ptyfs_close },		/* close */
    153 	{ &vop_access_desc, ptyfs_access },		/* access */
    154 	{ &vop_accessx_desc, genfs_accessx },		/* accessx */
    155 	{ &vop_getattr_desc, ptyfs_getattr },		/* getattr */
    156 	{ &vop_setattr_desc, ptyfs_setattr },		/* setattr */
    157 	{ &vop_read_desc, ptyfs_read },			/* read */
    158 	{ &vop_write_desc, ptyfs_write },		/* write */
    159 	{ &vop_fallocate_desc, genfs_eopnotsupp },	/* fallocate */
    160 	{ &vop_fdiscard_desc, genfs_eopnotsupp },	/* fdiscard */
    161 	{ &vop_ioctl_desc, ptyfs_ioctl },		/* ioctl */
    162 	{ &vop_fcntl_desc, genfs_fcntl },		/* fcntl */
    163 	{ &vop_poll_desc, ptyfs_poll },			/* poll */
    164 	{ &vop_kqfilter_desc, ptyfs_kqfilter },		/* kqfilter */
    165 	{ &vop_revoke_desc, genfs_revoke },		/* revoke */
    166 	{ &vop_mmap_desc, genfs_eopnotsupp },		/* mmap */
    167 	{ &vop_fsync_desc, genfs_nullop },		/* fsync */
    168 	{ &vop_seek_desc, genfs_nullop },		/* seek */
    169 	{ &vop_remove_desc, genfs_eopnotsupp },		/* remove */
    170 	{ &vop_link_desc, genfs_eopnotsupp },		/* link */
    171 	{ &vop_rename_desc, genfs_eopnotsupp },		/* rename */
    172 	{ &vop_mkdir_desc, genfs_eopnotsupp },		/* mkdir */
    173 	{ &vop_rmdir_desc, genfs_eopnotsupp },		/* rmdir */
    174 	{ &vop_symlink_desc, genfs_eopnotsupp },	/* symlink */
    175 	{ &vop_readdir_desc, ptyfs_readdir },		/* readdir */
    176 	{ &vop_readlink_desc, genfs_eopnotsupp },	/* readlink */
    177 	{ &vop_abortop_desc, genfs_abortop },		/* abortop */
    178 	{ &vop_inactive_desc, ptyfs_inactive },		/* inactive */
    179 	{ &vop_reclaim_desc, ptyfs_reclaim },		/* reclaim */
    180 	{ &vop_lock_desc, genfs_lock },			/* lock */
    181 	{ &vop_unlock_desc, genfs_unlock },		/* unlock */
    182 	{ &vop_bmap_desc, genfs_eopnotsupp },		/* bmap */
    183 	{ &vop_strategy_desc, genfs_badop },		/* strategy */
    184 	{ &vop_print_desc, ptyfs_print },		/* print */
    185 	{ &vop_islocked_desc, genfs_islocked },		/* islocked */
    186 	{ &vop_pathconf_desc, ptyfs_pathconf },		/* pathconf */
    187 	{ &vop_advlock_desc, ptyfs_advlock },		/* advlock */
    188 	{ &vop_bwrite_desc, genfs_eopnotsupp },		/* bwrite */
    189 	{ &vop_putpages_desc, genfs_null_putpages },	/* putpages */
    190 	{ NULL, NULL }
    191 };
    192 const struct vnodeopv_desc ptyfs_vnodeop_opv_desc =
    193 	{ &ptyfs_vnodeop_p, ptyfs_vnodeop_entries };
    194 
    195 /*
    196  * free any private data and remove the node
    197  * from any private lists.
    198  */
    199 int
    200 ptyfs_reclaim(void *v)
    201 {
    202 	struct vop_reclaim_v2_args /* {
    203 		struct vnode *a_vp;
    204 	} */ *ap = v;
    205 	struct vnode *vp = ap->a_vp;
    206 
    207 	VOP_UNLOCK(vp);
    208 
    209 	vp->v_data = NULL;
    210 	return 0;
    211 }
    212 
    213 int
    214 ptyfs_inactive(void *v)
    215 {
    216 	struct vop_inactive_v2_args /* {
    217 		struct vnode *a_vp;
    218 		bool *a_recycle;
    219 	} */ *ap = v;
    220 	struct vnode *vp = ap->a_vp;
    221 	struct ptyfsnode *ptyfs = VTOPTYFS(vp);
    222 
    223 	if (ptyfs->ptyfs_type == PTYFSptc)
    224 		ptyfs_clr_active(vp->v_mount, ptyfs->ptyfs_pty);
    225 
    226 	return 0;
    227 }
    228 
    229 /*
    230  * Return POSIX pathconf information applicable to special devices.
    231  */
    232 int
    233 ptyfs_pathconf(void *v)
    234 {
    235 	struct vop_pathconf_args /* {
    236 		struct vnode *a_vp;
    237 		int a_name;
    238 		register_t *a_retval;
    239 	} */ *ap = v;
    240 
    241 	switch (ap->a_name) {
    242 	case _PC_LINK_MAX:
    243 		*ap->a_retval = LINK_MAX;
    244 		return 0;
    245 	case _PC_MAX_CANON:
    246 		*ap->a_retval = MAX_CANON;
    247 		return 0;
    248 	case _PC_MAX_INPUT:
    249 		*ap->a_retval = MAX_INPUT;
    250 		return 0;
    251 	case _PC_PIPE_BUF:
    252 		*ap->a_retval = PIPE_BUF;
    253 		return 0;
    254 	case _PC_CHOWN_RESTRICTED:
    255 		*ap->a_retval = 1;
    256 		return 0;
    257 	case _PC_VDISABLE:
    258 		*ap->a_retval = _POSIX_VDISABLE;
    259 		return 0;
    260 	case _PC_SYNC_IO:
    261 		*ap->a_retval = 1;
    262 		return 0;
    263 	default:
    264 		return genfs_pathconf(ap);
    265 	}
    266 }
    267 
    268 /*
    269  * _print is used for debugging.
    270  * just print a readable description
    271  * of (vp).
    272  */
    273 int
    274 ptyfs_print(void *v)
    275 {
    276 	struct vop_print_args /* {
    277 		struct vnode *a_vp;
    278 	} */ *ap = v;
    279 	struct ptyfsnode *ptyfs = VTOPTYFS(ap->a_vp);
    280 
    281 	printf("tag VT_PTYFS, type %d, pty %d\n",
    282 	    ptyfs->ptyfs_type, ptyfs->ptyfs_pty);
    283 	return 0;
    284 }
    285 
    286 /*
    287  * support advisory locking on pty nodes
    288  */
    289 int
    290 ptyfs_advlock(void *v)
    291 {
    292 	struct vop_print_args /* {
    293 		struct vnode *a_vp;
    294 	} */ *ap = v;
    295 	struct ptyfsnode *ptyfs = VTOPTYFS(ap->a_vp);
    296 
    297 	switch (ptyfs->ptyfs_type) {
    298 	case PTYFSpts:
    299 	case PTYFSptc:
    300 		return spec_advlock(v);
    301 	default:
    302 		return EOPNOTSUPP;
    303 	}
    304 }
    305 
    306 /*
    307  * Invent attributes for ptyfsnode (vp) and store
    308  * them in (vap).
    309  * Directories lengths are returned as zero since
    310  * any real length would require the genuine size
    311  * to be computed, and nothing cares anyway.
    312  *
    313  * this is relatively minimal for ptyfs.
    314  */
    315 int
    316 ptyfs_getattr(void *v)
    317 {
    318 	struct vop_getattr_args /* {
    319 		struct vnode *a_vp;
    320 		struct vattr *a_vap;
    321 		kauth_cred_t a_cred;
    322 	} */ *ap = v;
    323 	struct ptyfsnode *ptyfs = VTOPTYFS(ap->a_vp);
    324 	struct vattr *vap = ap->a_vap;
    325 
    326 	PTYFS_ITIMES(ptyfs, NULL, NULL, NULL);
    327 
    328 	/* start by zeroing out the attributes */
    329 	vattr_null(vap);
    330 
    331 	/* next do all the common fields */
    332 	vap->va_type = ap->a_vp->v_type;
    333 	vap->va_fsid = ap->a_vp->v_mount->mnt_stat.f_fsidx.__fsid_val[0];
    334 	vap->va_fileid = ptyfs->ptyfs_fileno;
    335 	vap->va_gen = 0;
    336 	vap->va_flags = 0;
    337 	vap->va_blocksize = PAGE_SIZE;
    338 
    339 	vap->va_atime = ptyfs->ptyfs_atime;
    340 	vap->va_mtime = ptyfs->ptyfs_mtime;
    341 	vap->va_ctime = ptyfs->ptyfs_ctime;
    342 	vap->va_birthtime = ptyfs->ptyfs_birthtime;
    343 	vap->va_mode = ptyfs->ptyfs_mode;
    344 	vap->va_flags = ptyfs->ptyfs_flags;
    345 	vap->va_uid = ptyfs->ptyfs_uid;
    346 	vap->va_gid = ptyfs->ptyfs_gid;
    347 
    348 	switch (ptyfs->ptyfs_type) {
    349 	case PTYFSpts:
    350 	case PTYFSptc:
    351 		if (pty_isfree(ptyfs->ptyfs_pty, 1))
    352 			return ENOENT;
    353 		vap->va_bytes = vap->va_size = 0;
    354 		vap->va_rdev = ap->a_vp->v_rdev;
    355 		vap->va_nlink = 1;
    356 		break;
    357 	case PTYFSroot:
    358 		vap->va_rdev = 0;
    359 		vap->va_bytes = vap->va_size = DEV_BSIZE;
    360 		vap->va_nlink = 2;
    361 		break;
    362 	default:
    363 		return EOPNOTSUPP;
    364 	}
    365 
    366 	return 0;
    367 }
    368 
    369 /*ARGSUSED*/
    370 int
    371 ptyfs_setattr(void *v)
    372 {
    373 	struct vop_setattr_args /* {
    374 		struct vnodeop_desc *a_desc;
    375 		struct vnode *a_vp;
    376 		struct vattr *a_vap;
    377 		kauth_cred_t a_cred;
    378 	} */ *ap = v;
    379 	struct vnode *vp = ap->a_vp;
    380 	struct ptyfsnode *ptyfs = VTOPTYFS(vp);
    381 	struct vattr *vap = ap->a_vap;
    382 	kauth_cred_t cred = ap->a_cred;
    383 	struct lwp *l = curlwp;
    384 	int error;
    385 	kauth_action_t action = KAUTH_VNODE_WRITE_FLAGS;
    386 	bool changing_sysflags = false;
    387 
    388 	if (vap->va_size != VNOVALSIZE) {
    389  		switch (ptyfs->ptyfs_type) {
    390  		case PTYFSroot:
    391  			return EISDIR;
    392  		case PTYFSpts:
    393  		case PTYFSptc:
    394 			break;
    395 		default:
    396 			return EINVAL;
    397 		}
    398 	}
    399 
    400 	if (vap->va_flags != VNOVALFLAGS) {
    401 		if (vp->v_mount->mnt_flag & MNT_RDONLY)
    402 			return EROFS;
    403 
    404 		/* Immutable and append-only flags are not supported on ptyfs. */
    405 		if (vap->va_flags & (IMMUTABLE | APPEND))
    406 			return EINVAL;
    407 
    408 		/* Snapshot flag cannot be set or cleared */
    409 		if ((vap->va_flags & SF_SNAPSHOT) != (ptyfs->ptyfs_flags & SF_SNAPSHOT))
    410 			return EPERM;
    411 
    412 		if ((ptyfs->ptyfs_flags & SF_SETTABLE) != (vap->va_flags & SF_SETTABLE)) {
    413 			changing_sysflags = true;
    414 			action |= KAUTH_VNODE_WRITE_SYSFLAGS;
    415 		}
    416 
    417 		error = kauth_authorize_vnode(cred, action, vp, NULL,
    418 		    genfs_can_chflags(vp, cred, ptyfs->ptyfs_uid,
    419 		    changing_sysflags));
    420 		if (error)
    421 			return error;
    422 
    423 		if (changing_sysflags) {
    424 			ptyfs->ptyfs_flags = vap->va_flags;
    425 		} else {
    426 			ptyfs->ptyfs_flags &= SF_SETTABLE;
    427 			ptyfs->ptyfs_flags |= (vap->va_flags & UF_SETTABLE);
    428 		}
    429 		ptyfs->ptyfs_status |= PTYFS_CHANGE;
    430 	}
    431 
    432 	/*
    433 	 * Go through the fields and update iff not VNOVAL.
    434 	 */
    435 	if (vap->va_uid != (uid_t)VNOVAL || vap->va_gid != (gid_t)VNOVAL) {
    436 		if (vp->v_mount->mnt_flag & MNT_RDONLY)
    437 			return EROFS;
    438 		error = ptyfs_chown(vp, vap->va_uid, vap->va_gid, cred, l);
    439 		if (error)
    440 			return error;
    441 	}
    442 
    443 	if (vap->va_atime.tv_sec != VNOVAL || vap->va_mtime.tv_sec != VNOVAL ||
    444 	    vap->va_birthtime.tv_sec != VNOVAL) {
    445 		if (vp->v_mount->mnt_flag & MNT_RDONLY)
    446 			return EROFS;
    447 		if ((ptyfs->ptyfs_flags & SF_SNAPSHOT) != 0)
    448 			return EPERM;
    449 		error = kauth_authorize_vnode(cred, KAUTH_VNODE_WRITE_TIMES, vp,
    450 		    NULL, genfs_can_chtimes(vp, cred, ptyfs->ptyfs_uid,
    451 		    vap->va_vaflags));
    452 		if (error)
    453 			return (error);
    454 		if (vap->va_atime.tv_sec != VNOVAL)
    455 			if (!(vp->v_mount->mnt_flag & MNT_NOATIME))
    456 				ptyfs->ptyfs_status |= PTYFS_ACCESS;
    457 		if (vap->va_mtime.tv_sec != VNOVAL) {
    458 			ptyfs->ptyfs_status |= PTYFS_CHANGE | PTYFS_MODIFY;
    459 			if (vp->v_mount->mnt_flag & MNT_RELATIME)
    460 				ptyfs->ptyfs_status |= PTYFS_ACCESS;
    461 		}
    462 		if (vap->va_birthtime.tv_sec != VNOVAL)
    463 			ptyfs->ptyfs_birthtime = vap->va_birthtime;
    464 		ptyfs->ptyfs_status |= PTYFS_CHANGE;
    465 		error = ptyfs_update(vp, &vap->va_atime, &vap->va_mtime, 0);
    466 		if (error)
    467 			return error;
    468 	}
    469 	if (vap->va_mode != (mode_t)VNOVAL) {
    470 		if (vp->v_mount->mnt_flag & MNT_RDONLY)
    471 			return EROFS;
    472 		if ((ptyfs->ptyfs_flags & SF_SNAPSHOT) != 0 &&
    473 		    (vap->va_mode &
    474 		    (S_IXUSR|S_IWUSR|S_IXGRP|S_IWGRP|S_IXOTH|S_IWOTH)))
    475 			return EPERM;
    476 		error = ptyfs_chmod(vp, vap->va_mode, cred, l);
    477 		if (error)
    478 			return error;
    479 	}
    480 	return 0;
    481 }
    482 
    483 /*
    484  * Change the mode on a file.
    485  * Inode must be locked before calling.
    486  */
    487 static int
    488 ptyfs_chmod(struct vnode *vp, mode_t mode, kauth_cred_t cred, struct lwp *l)
    489 {
    490 	struct ptyfsnode *ptyfs = VTOPTYFS(vp);
    491 	int error;
    492 
    493 	error = kauth_authorize_vnode(cred, KAUTH_VNODE_WRITE_SECURITY, vp,
    494 	    NULL, genfs_can_chmod(vp, cred, ptyfs->ptyfs_uid, ptyfs->ptyfs_gid,
    495 	    mode));
    496 	if (error)
    497 		return (error);
    498 
    499 	ptyfs->ptyfs_mode &= ~ALLPERMS;
    500 	ptyfs->ptyfs_mode |= (mode & ALLPERMS);
    501 	return 0;
    502 }
    503 
    504 /*
    505  * Perform chown operation on inode ip;
    506  * inode must be locked prior to call.
    507  */
    508 static int
    509 ptyfs_chown(struct vnode *vp, uid_t uid, gid_t gid, kauth_cred_t cred,
    510     struct lwp *l)
    511 {
    512 	struct ptyfsnode *ptyfs = VTOPTYFS(vp);
    513 	int error;
    514 
    515 	if (uid == (uid_t)VNOVAL)
    516 		uid = ptyfs->ptyfs_uid;
    517 	if (gid == (gid_t)VNOVAL)
    518 		gid = ptyfs->ptyfs_gid;
    519 
    520 	error = kauth_authorize_vnode(cred, KAUTH_VNODE_CHANGE_OWNERSHIP, vp,
    521 	    NULL, genfs_can_chown(vp, cred, ptyfs->ptyfs_uid, ptyfs->ptyfs_gid,
    522 	    uid, gid));
    523 	if (error)
    524 		return (error);
    525 
    526 	ptyfs->ptyfs_gid = gid;
    527 	ptyfs->ptyfs_uid = uid;
    528 	return 0;
    529 }
    530 
    531 /*
    532  * implement access checking.
    533  *
    534  * actually, the check for super-user is slightly
    535  * broken since it will allow read access to write-only
    536  * objects.  this doesn't cause any particular trouble
    537  * but does mean that the i/o entry points need to check
    538  * that the operation really does make sense.
    539  */
    540 int
    541 ptyfs_access(void *v)
    542 {
    543 	struct vop_access_args /* {
    544 		struct vnode *a_vp;
    545 		accmode_t a_accmode;
    546 		kauth_cred_t a_cred;
    547 	} */ *ap = v;
    548 	struct vattr va;
    549 	int error;
    550 
    551 	if ((error = VOP_GETATTR(ap->a_vp, &va, ap->a_cred)) != 0)
    552 		return error;
    553 
    554 	return kauth_authorize_vnode(ap->a_cred,
    555 	    KAUTH_ACCESS_ACTION(ap->a_accmode, ap->a_vp->v_type, va.va_mode),
    556 	    ap->a_vp, NULL, genfs_can_access(ap->a_vp, ap->a_cred, va.va_uid,
    557 	    va.va_gid, va.va_mode, NULL, ap->a_accmode));
    558 }
    559 
    560 /*
    561  * lookup.  this is incredibly complicated in the
    562  * general case, however for most pseudo-filesystems
    563  * very little needs to be done.
    564  *
    565  * Locking isn't hard here, just poorly documented.
    566  *
    567  * If we're looking up ".", just vref the parent & return it.
    568  *
    569  * If we're looking up "..", unlock the parent, and lock "..". If everything
    570  * went ok, try to re-lock the parent. We do this to prevent lock races.
    571  *
    572  * For anything else, get the needed node.
    573  *
    574  * We try to exit with the parent locked in error cases.
    575  */
    576 int
    577 ptyfs_lookup(void *v)
    578 {
    579 	struct vop_lookup_v2_args /* {
    580 		struct vnode * a_dvp;
    581 		struct vnode ** a_vpp;
    582 		struct componentname * a_cnp;
    583 	} */ *ap = v;
    584 	struct componentname *cnp = ap->a_cnp;
    585 	struct vnode **vpp = ap->a_vpp;
    586 	struct vnode *dvp = ap->a_dvp;
    587 	const char *pname = cnp->cn_nameptr;
    588 	struct ptyfsnode *ptyfs;
    589 	int pty, error;
    590 
    591 	*vpp = NULL;
    592 
    593 	if (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)
    594 		return EROFS;
    595 
    596 	if (cnp->cn_namelen == 1 && *pname == '.') {
    597 		*vpp = dvp;
    598 		vref(dvp);
    599 		return 0;
    600 	}
    601 
    602 	ptyfs = VTOPTYFS(dvp);
    603 	switch (ptyfs->ptyfs_type) {
    604 	case PTYFSroot:
    605 		/*
    606 		 * Shouldn't get here with .. in the root node.
    607 		 */
    608 		if (cnp->cn_flags & ISDOTDOT)
    609 			return EIO;
    610 
    611 		pty = atoi(pname, cnp->cn_namelen);
    612 		if (pty < 0 || ptyfs_next_active(dvp->v_mount, pty) != pty)
    613 			break;
    614 		error = ptyfs_allocvp(dvp->v_mount, vpp, PTYFSpts, pty);
    615 		if (error)
    616 			return error;
    617 		if (ptyfs_next_active(dvp->v_mount, pty) != pty) {
    618 			vrele(*vpp);
    619 			*vpp = NULL;
    620 			return ENOENT;
    621 		}
    622 		return 0;
    623 
    624 	default:
    625 		return ENOTDIR;
    626 	}
    627 
    628 	return cnp->cn_nameiop == LOOKUP ? ENOENT : EROFS;
    629 }
    630 
    631 /*
    632  * readdir returns directory entries from ptyfsnode (vp).
    633  *
    634  * the strategy here with ptyfs is to generate a single
    635  * directory entry at a time (struct dirent) and then
    636  * copy that out to userland using uiomove.  a more efficient
    637  * though more complex implementation, would try to minimize
    638  * the number of calls to uiomove().  for ptyfs, this is
    639  * hardly worth the added code complexity.
    640  *
    641  * this should just be done through read()
    642  */
    643 int
    644 ptyfs_readdir(void *v)
    645 {
    646 	struct vop_readdir_args /* {
    647 		struct vnode *a_vp;
    648 		struct uio *a_uio;
    649 		kauth_cred_t a_cred;
    650 		int *a_eofflag;
    651 		off_t **a_cookies;
    652 		int *a_ncookies;
    653 	} */ *ap = v;
    654 	struct uio *uio = ap->a_uio;
    655 	struct dirent *dp;
    656 	struct ptyfsnode *ptyfs;
    657 	off_t i;
    658 	int error;
    659 	off_t *cookies = NULL;
    660 	int ncookies;
    661 	struct vnode *vp;
    662 	int n, nc = 0;
    663 
    664 	vp = ap->a_vp;
    665 	ptyfs = VTOPTYFS(vp);
    666 
    667 	if (uio->uio_resid < UIO_MX)
    668 		return EINVAL;
    669 	if (uio->uio_offset < 0)
    670 		return EINVAL;
    671 
    672 	dp = malloc(sizeof(struct dirent), M_PTYFSTMP, M_WAITOK | M_ZERO);
    673 
    674 	error = 0;
    675 	i = uio->uio_offset;
    676 	dp->d_reclen = UIO_MX;
    677 	ncookies = uio->uio_resid / UIO_MX;
    678 
    679 	if (ptyfs->ptyfs_type != PTYFSroot) {
    680 		error = ENOTDIR;
    681 		goto out;
    682 	}
    683 
    684 	if (i >= npty)
    685 		goto out;
    686 
    687 	if (ap->a_ncookies) {
    688 		ncookies = uimin(ncookies, (npty + 2 - i));
    689 		cookies = malloc(ncookies * sizeof (off_t),
    690 		    M_TEMP, M_WAITOK);
    691 		*ap->a_cookies = cookies;
    692 	}
    693 
    694 	for (; i < 2 && uio->uio_resid >= UIO_MX; i++) {
    695 		/* `.' and/or `..' */
    696 		dp->d_fileno = PTYFS_FILENO(PTYFSroot, 0);
    697 		dp->d_namlen = i + 1;
    698 		(void)memcpy(dp->d_name, "..", dp->d_namlen);
    699 		dp->d_name[i + 1] = '\0';
    700 		dp->d_type = DT_DIR;
    701 		if ((error = uiomove(dp, UIO_MX, uio)) != 0)
    702 			goto out;
    703 		if (cookies)
    704 			*cookies++ = i + 1;
    705 		nc++;
    706 	}
    707 	while (uio->uio_resid >= UIO_MX) {
    708 		/* check for used ptys */
    709 		n = ptyfs_next_active(vp->v_mount, i - 2);
    710 		if (n < 0)
    711 			break;
    712 		dp->d_fileno = PTYFS_FILENO(PTYFSpts, n);
    713 		dp->d_namlen = snprintf(dp->d_name, sizeof(dp->d_name),
    714 		    "%lld", (long long)(n));
    715 		dp->d_type = DT_CHR;
    716 		if ((error = uiomove(dp, UIO_MX, uio)) != 0)
    717 			goto out;
    718 		i = n + 3;
    719 		if (cookies)
    720 			*cookies++ = i;
    721 		nc++;
    722 	}
    723 
    724 out:
    725 	/* not pertinent in error cases */
    726 	ncookies = nc;
    727 
    728 	if (ap->a_ncookies) {
    729 		if (error) {
    730 			if (cookies)
    731 				free(*ap->a_cookies, M_TEMP);
    732 			*ap->a_ncookies = 0;
    733 			*ap->a_cookies = NULL;
    734 		} else
    735 			*ap->a_ncookies = ncookies;
    736 	}
    737 	uio->uio_offset = i;
    738 	free(dp, M_PTYFSTMP);
    739 	return error;
    740 }
    741 
    742 int
    743 ptyfs_open(void *v)
    744 {
    745 	struct vop_open_args /* {
    746 		struct vnode *a_vp;
    747 		int  a_mode;
    748 		kauth_cred_t a_cred;
    749 	} */ *ap = v;
    750 	struct vnode *vp = ap->a_vp;
    751 	struct ptyfsnode *ptyfs = VTOPTYFS(vp);
    752 
    753 	switch (ptyfs->ptyfs_type) {
    754 	case PTYFSpts:
    755 	case PTYFSptc:
    756 		return spec_open(v);
    757 	case PTYFSroot:
    758 		return 0;
    759 	default:
    760 		return EINVAL;
    761 	}
    762 }
    763 
    764 int
    765 ptyfs_close(void *v)
    766 {
    767 	struct vop_close_args /* {
    768 		struct vnode *a_vp;
    769 		int  a_fflag;
    770 		kauth_cred_t a_cred;
    771 	} */ *ap = v;
    772 	struct vnode *vp = ap->a_vp;
    773 	struct ptyfsnode *ptyfs = VTOPTYFS(vp);
    774 
    775 	mutex_enter(vp->v_interlock);
    776 	if (vrefcnt(vp) > 1)
    777 		PTYFS_ITIMES(ptyfs, NULL, NULL, NULL);
    778 	mutex_exit(vp->v_interlock);
    779 
    780 	switch (ptyfs->ptyfs_type) {
    781 	case PTYFSpts:
    782 	case PTYFSptc:
    783 		return spec_close(v);
    784 	case PTYFSroot:
    785 		return 0;
    786 	default:
    787 		return EINVAL;
    788 	}
    789 }
    790 
    791 int
    792 ptyfs_read(void *v)
    793 {
    794 	struct vop_read_args /* {
    795 		struct vnode *a_vp;
    796 		struct uio *a_uio;
    797 		int  a_ioflag;
    798 		kauth_cred_t a_cred;
    799 	} */ *ap = v;
    800 	struct timespec ts;
    801 	struct vnode *vp = ap->a_vp;
    802 	struct ptyfsnode *ptyfs = VTOPTYFS(vp);
    803 	int error;
    804 
    805 	if (vp->v_type == VDIR)
    806 		return EISDIR;
    807 
    808 	ptyfs->ptyfs_status |= PTYFS_ACCESS;
    809 	/* hardclock() resolution is good enough for ptyfs */
    810 	getnanotime(&ts);
    811 	(void)ptyfs_update(vp, &ts, &ts, 0);
    812 
    813 	switch (ptyfs->ptyfs_type) {
    814 	case PTYFSpts:
    815 	case PTYFSptc:
    816 		VOP_UNLOCK(vp);
    817 		error = cdev_read(vp->v_rdev, ap->a_uio, ap->a_ioflag);
    818 		vn_lock(vp, LK_RETRY|LK_EXCLUSIVE);
    819 		return error;
    820 	default:
    821 		return EOPNOTSUPP;
    822 	}
    823 }
    824 
    825 int
    826 ptyfs_write(void *v)
    827 {
    828 	struct vop_write_args /* {
    829 		struct vnode *a_vp;
    830 		struct uio *a_uio;
    831 		int  a_ioflag;
    832 		kauth_cred_t a_cred;
    833 	} */ *ap = v;
    834 	struct timespec ts;
    835 	struct vnode *vp = ap->a_vp;
    836 	struct ptyfsnode *ptyfs = VTOPTYFS(vp);
    837 	int error;
    838 
    839 	ptyfs->ptyfs_status |= PTYFS_MODIFY;
    840 	getnanotime(&ts);
    841 	(void)ptyfs_update(vp, &ts, &ts, 0);
    842 
    843 	switch (ptyfs->ptyfs_type) {
    844 	case PTYFSpts:
    845 	case PTYFSptc:
    846 		VOP_UNLOCK(vp);
    847 		error = cdev_write(vp->v_rdev, ap->a_uio, ap->a_ioflag);
    848 		vn_lock(vp, LK_RETRY|LK_EXCLUSIVE);
    849 		return error;
    850 	default:
    851 		return EOPNOTSUPP;
    852 	}
    853 }
    854 
    855 int
    856 ptyfs_ioctl(void *v)
    857 {
    858 	struct vop_ioctl_args /* {
    859 		struct vnode *a_vp;
    860 		u_long a_command;
    861 		void *a_data;
    862 		int  a_fflag;
    863 		kauth_cred_t a_cred;
    864 	} */ *ap = v;
    865 	struct vnode *vp = ap->a_vp;
    866 	struct ptyfsnode *ptyfs = VTOPTYFS(vp);
    867 
    868 	switch (ptyfs->ptyfs_type) {
    869 	case PTYFSpts:
    870 	case PTYFSptc:
    871 		return cdev_ioctl(vp->v_rdev, ap->a_command,
    872 		    ap->a_data, ap->a_fflag, curlwp);
    873 	default:
    874 		return EOPNOTSUPP;
    875 	}
    876 }
    877 
    878 int
    879 ptyfs_poll(void *v)
    880 {
    881 	struct vop_poll_args /* {
    882 		struct vnode *a_vp;
    883 		int a_events;
    884 	} */ *ap = v;
    885 	struct vnode *vp = ap->a_vp;
    886 	struct ptyfsnode *ptyfs = VTOPTYFS(vp);
    887 
    888 	switch (ptyfs->ptyfs_type) {
    889 	case PTYFSpts:
    890 	case PTYFSptc:
    891 		return cdev_poll(vp->v_rdev, ap->a_events, curlwp);
    892 	default:
    893 		return genfs_poll(v);
    894 	}
    895 }
    896 
    897 int
    898 ptyfs_kqfilter(void *v)
    899 {
    900 	struct vop_kqfilter_args /* {
    901 		struct vnode *a_vp;
    902 		struct knote *a_kn;
    903 	} */ *ap = v;
    904 	struct vnode *vp = ap->a_vp;
    905 	struct ptyfsnode *ptyfs = VTOPTYFS(vp);
    906 
    907 	switch (ptyfs->ptyfs_type) {
    908 	case PTYFSpts:
    909 	case PTYFSptc:
    910 		return cdev_kqfilter(vp->v_rdev, ap->a_kn);
    911 	default:
    912 		return genfs_kqfilter(v);
    913 	}
    914 }
    915 
    916 static int
    917 ptyfs_update(struct vnode *vp, const struct timespec *acc,
    918     const struct timespec *mod, int flags)
    919 {
    920 	struct ptyfsnode *ptyfs = VTOPTYFS(vp);
    921 
    922 	if (vp->v_mount->mnt_flag & MNT_RDONLY)
    923 		return 0;
    924 
    925 	PTYFS_ITIMES(ptyfs, acc, mod, NULL);
    926 	return 0;
    927 }
    928 
    929 void
    930 ptyfs_itimes(struct ptyfsnode *ptyfs, const struct timespec *acc,
    931     const struct timespec *mod, const struct timespec *cre)
    932 {
    933 	struct timespec now;
    934 
    935 	KASSERT(ptyfs->ptyfs_status & (PTYFS_ACCESS|PTYFS_CHANGE|PTYFS_MODIFY));
    936 
    937 	getnanotime(&now);
    938 	if (ptyfs->ptyfs_status & PTYFS_ACCESS) {
    939 		if (acc == NULL)
    940 			acc = &now;
    941 		ptyfs->ptyfs_atime = *acc;
    942 	}
    943 	if (ptyfs->ptyfs_status & PTYFS_MODIFY) {
    944 		if (mod == NULL)
    945 			mod = &now;
    946 		ptyfs->ptyfs_mtime = *mod;
    947 	}
    948 	if (ptyfs->ptyfs_status & PTYFS_CHANGE) {
    949 		if (cre == NULL)
    950 			cre = &now;
    951 		ptyfs->ptyfs_ctime = *cre;
    952 	}
    953 	ptyfs->ptyfs_status &= ~(PTYFS_ACCESS|PTYFS_CHANGE|PTYFS_MODIFY);
    954 }
    955 
    956 /*
    957  * convert decimal ascii to int
    958  */
    959 static int
    960 atoi(const char *b, size_t len)
    961 {
    962 	int p = 0;
    963 
    964 	while (len--) {
    965 		char c = *b++;
    966 		if (c < '0' || c > '9')
    967 			return -1;
    968 		p = 10 * p + (c - '0');
    969 	}
    970 
    971 	return p;
    972 }
    973