1/*-
2 * Copyright (c) 1992, 1993, 1995
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * This code is derived from software donated to Berkeley by
6 * Jan-Simon Pendry.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of the University nor the names of its contributors
17 *    may be used to endorse or promote products derived from this software
18 *    without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 *
32 *	@(#)fdesc_vfsops.c	8.4 (Berkeley) 1/21/94
33 *
34 * $FreeBSD: stable/11/sys/fs/fdescfs/fdesc_vfsops.c 322340 2017-08-10 05:38:31Z dchagin $
35 */
36
37/*
38 * /dev/fd Filesystem
39 */
40
41#include <sys/param.h>
42#include <sys/systm.h>
43#include <sys/filedesc.h>
44#include <sys/kernel.h>
45#include <sys/jail.h>
46#include <sys/lock.h>
47#include <sys/mutex.h>
48#include <sys/malloc.h>
49#include <sys/mount.h>
50#include <sys/proc.h>
51#include <sys/racct.h>
52#include <sys/resourcevar.h>
53#include <sys/vnode.h>
54
55#include <fs/fdescfs/fdesc.h>
56
57static MALLOC_DEFINE(M_FDESCMNT, "fdesc_mount", "FDESC mount structure");
58
59static vfs_cmount_t	fdesc_cmount;
60static vfs_mount_t	fdesc_mount;
61static vfs_unmount_t	fdesc_unmount;
62static vfs_statfs_t	fdesc_statfs;
63static vfs_root_t	fdesc_root;
64
65/*
66 * Compatibility shim for old mount(2) system call.
67 */
68int
69fdesc_cmount(struct mntarg *ma, void *data, uint64_t flags)
70{
71
72	return kernel_mount(ma, flags);
73}
74
75/*
76 * Mount the per-process file descriptors (/dev/fd)
77 */
78static int
79fdesc_mount(struct mount *mp)
80{
81	struct fdescmount *fmp;
82	struct thread *td = curthread;
83	struct vnode *rvp;
84	int error;
85
86	if (!prison_allow(td->td_ucred, PR_ALLOW_MOUNT_FDESCFS))
87		return (EPERM);
88
89	/*
90	 * Update is a no-op
91	 */
92	if (mp->mnt_flag & (MNT_UPDATE | MNT_ROOTFS))
93		return (EOPNOTSUPP);
94
95	fmp = malloc(sizeof(struct fdescmount),
96				M_FDESCMNT, M_WAITOK);	/* XXX */
97
98	/*
99	 * We need to initialize a few bits of our local mount point struct to
100	 * avoid confusion in allocvp.
101	 */
102	mp->mnt_data = fmp;
103	fmp->flags = 0;
104	if (vfs_getopt(mp->mnt_optnew, "linrdlnk", NULL, NULL) == 0)
105		fmp->flags |= FMNT_LINRDLNKF;
106	error = fdesc_allocvp(Froot, -1, FD_ROOT, mp, &rvp);
107	if (error) {
108		free(fmp, M_FDESCMNT);
109		mp->mnt_data = NULL;
110		return (error);
111	}
112	rvp->v_type = VDIR;
113	rvp->v_vflag |= VV_ROOT;
114	fmp->f_root = rvp;
115	VOP_UNLOCK(rvp, 0);
116	/* XXX -- don't mark as local to work around fts() problems */
117	/*mp->mnt_flag |= MNT_LOCAL;*/
118	vfs_getnewfsid(mp);
119
120	vfs_mountedfrom(mp, "fdescfs");
121	return (0);
122}
123
124static int
125fdesc_unmount(struct mount *mp, int mntflags)
126{
127	struct fdescmount *fmp;
128	int error, flags;
129
130	flags = 0;
131	fmp = mp->mnt_data;
132	if (mntflags & MNT_FORCE) {
133		/* The hash mutex protects the private mount flags. */
134		mtx_lock(&fdesc_hashmtx);
135		fmp->flags |= FMNT_UNMOUNTF;
136		mtx_unlock(&fdesc_hashmtx);
137		flags |= FORCECLOSE;
138	}
139
140	/*
141	 * Clear out buffer cache.  I don't think we
142	 * ever get anything cached at this level at the
143	 * moment, but who knows...
144	 *
145	 * There is 1 extra root vnode reference corresponding
146	 * to f_root.
147	 */
148	if ((error = vflush(mp, 1, flags, curthread)) != 0)
149		return (error);
150
151	/*
152	 * Finally, throw away the fdescmount structure.
153	 */
154	mp->mnt_data = NULL;
155	free(fmp, M_FDESCMNT);
156	return (0);
157}
158
159static int
160fdesc_root(struct mount *mp, int flags, struct vnode **vpp)
161{
162	struct vnode *vp;
163
164	/*
165	 * Return locked reference to root.
166	 */
167	vp = VFSTOFDESC(mp)->f_root;
168	vget(vp, LK_EXCLUSIVE | LK_RETRY, curthread);
169	*vpp = vp;
170	return (0);
171}
172
173static int
174fdesc_statfs(struct mount *mp, struct statfs *sbp)
175{
176	struct thread *td;
177	struct filedesc *fdp;
178	int lim;
179	int i;
180	int last;
181	int freefd;
182	uint64_t limit;
183
184	td = curthread;
185
186	/*
187	 * Compute number of free file descriptors.
188	 * [ Strange results will ensue if the open file
189	 * limit is ever reduced below the current number
190	 * of open files... ]
191	 */
192	lim = lim_cur(td, RLIMIT_NOFILE);
193	fdp = td->td_proc->p_fd;
194	FILEDESC_SLOCK(fdp);
195	limit = racct_get_limit(td->td_proc, RACCT_NOFILE);
196	if (lim > limit)
197		lim = limit;
198	last = min(fdp->fd_nfiles, lim);
199	freefd = 0;
200	for (i = fdp->fd_freefile; i < last; i++)
201		if (fdp->fd_ofiles[i].fde_file == NULL)
202			freefd++;
203
204	/*
205	 * Adjust for the fact that the fdesc array may not
206	 * have been fully allocated yet.
207	 */
208	if (fdp->fd_nfiles < lim)
209		freefd += (lim - fdp->fd_nfiles);
210	FILEDESC_SUNLOCK(fdp);
211
212	sbp->f_flags = 0;
213	sbp->f_bsize = DEV_BSIZE;
214	sbp->f_iosize = DEV_BSIZE;
215	sbp->f_blocks = 2;		/* 1K to keep df happy */
216	sbp->f_bfree = 0;
217	sbp->f_bavail = 0;
218	sbp->f_files = lim + 1;		/* Allow for "." */
219	sbp->f_ffree = freefd;		/* See comments above */
220	return (0);
221}
222
223static struct vfsops fdesc_vfsops = {
224	.vfs_cmount =		fdesc_cmount,
225	.vfs_init =		fdesc_init,
226	.vfs_mount =		fdesc_mount,
227	.vfs_root =		fdesc_root,
228	.vfs_statfs =		fdesc_statfs,
229	.vfs_uninit =		fdesc_uninit,
230	.vfs_unmount =		fdesc_unmount,
231};
232
233VFS_SET(fdesc_vfsops, fdescfs, VFCF_SYNTHETIC | VFCF_JAIL);
234