1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21 /*
22 * Copyright (c) 1999, 2010, Oracle and/or its affiliates. All rights reserved.
23 */
24
25 #include <sys/types.h>
26 #include <sys/param.h>
27 #include <sys/cmn_err.h>
28 #include <sys/cred.h>
29 #include <sys/debug.h>
30 #include <sys/errno.h>
31 #include <sys/proc.h>
32 #include <sys/procfs.h>
33 #include <sys/stat.h>
34 #include <sys/statvfs.h>
35 #include <sys/sysmacros.h>
36 #include <sys/systm.h>
37 #include <sys/var.h>
38 #include <sys/vfs.h>
39 #include <sys/vfs_opreg.h>
40 #include <sys/vnode.h>
41 #include <sys/mode.h>
42 #include <sys/signal.h>
43 #include <sys/user.h>
44 #include <sys/mount.h>
45 #include <sys/bitmap.h>
46 #include <sys/kmem.h>
47 #include <sys/policy.h>
48 #include <fs/fs_subr.h>
49 #include <sys/fs/mntdata.h>
50 #include <sys/zone.h>
51
52 /*
53 * This is the loadable module wrapper.
54 */
55 #include <sys/modctl.h>
56
57 static int mntinit(int, char *);
58
59 static mntopts_t mnt_mntopts = {
60 0,
61 NULL
62 };
63
64 static vfsdef_t vfw = {
65 VFSDEF_VERSION,
66 "mntfs",
67 mntinit,
68 VSW_HASPROTO|VSW_STATS|VSW_ZMOUNT,
69 &mnt_mntopts
70 };
71
72 /*
73 * Module linkage information for the kernel.
74 */
75 extern struct mod_ops mod_fsops;
76
77 static struct modlfs modlfs = {
78 &mod_fsops, "mount information file system", &vfw
79 };
80
81 static struct modlinkage modlinkage = {
82 MODREV_1, (void *)&modlfs, NULL
83 };
84
85 int
86 _init(void)
87 {
88 return (mod_install(&modlinkage));
89 }
90
91 int
92 _info(struct modinfo *modinfop)
93 {
94 return (mod_info(&modlinkage, modinfop));
95 }
96
97 /*
98 * N.B.
99 * No _fini routine. The module cannot be unloaded once loaded.
100 * The NO_UNLOAD_STUB in modstubs.s must change if this module
101 * is ever modified to become unloadable.
102 */
103
104 extern int mntfstype;
105 static major_t mnt_major;
106 static minor_t mnt_minor;
107 static kmutex_t mnt_minor_lock;
108
109 /*
110 * /mnttab VFS operations vector.
111 */
112 static int mntmount(), mntunmount(), mntroot(), mntstatvfs();
113
114 static void
115 mntinitrootnode(mntnode_t *mnp)
116 {
117 struct vnode *vp;
118
119 bzero((caddr_t)mnp, sizeof (*mnp));
120
121 mnp->mnt_vnode = vn_alloc(KM_SLEEP);
122
123 vp = MTOV(mnp);
124
125 vp->v_flag = VROOT|VNOCACHE|VNOMAP|VNOSWAP|VNOMOUNT;
126 vn_setops(vp, mntvnodeops);
127 vp->v_type = VREG;
128 vp->v_data = (caddr_t)mnp;
129 }
130
131 static int
132 mntinit(int fstype, char *name)
133 {
134 static const fs_operation_def_t mnt_vfsops_template[] = {
135 VFSNAME_MOUNT, { .vfs_mount = mntmount },
136 VFSNAME_UNMOUNT, { .vfs_unmount = mntunmount },
137 VFSNAME_ROOT, { .vfs_root = mntroot },
138 VFSNAME_STATVFS, { .vfs_statvfs = mntstatvfs },
139 NULL, NULL
140 };
141 extern const fs_operation_def_t mnt_vnodeops_template[];
142 int error;
143
144 mntfstype = fstype;
145 ASSERT(mntfstype != 0);
146 /*
147 * Associate VFS ops vector with this fstype.
148 */
149 error = vfs_setfsops(fstype, mnt_vfsops_template, NULL);
150 if (error != 0) {
151 cmn_err(CE_WARN, "mntinit: bad vfs ops template");
152 return (error);
153 }
154
155 /* Vnode ops too. */
156
157 error = vn_make_ops(name, mnt_vnodeops_template, &mntvnodeops);
158 if (error != 0) {
159 (void) vfs_freevfsops_by_type(fstype);
160 cmn_err(CE_WARN, "mntinit: bad vnode ops template");
161 return (error);
162 }
163
164 /*
165 * Assign a unique "device" number (used by stat(2)).
166 */
167 if ((mnt_major = getudev()) == (major_t)-1) {
168 cmn_err(CE_WARN, "mntinit: can't get unique device number");
169 mnt_major = 0;
170 }
171 mutex_init(&mnt_minor_lock, NULL, MUTEX_DEFAULT, NULL);
172
173 return (0);
174 }
175
176 /* ARGSUSED */
177 static int
178 mntmount(struct vfs *vfsp, struct vnode *mvp,
179 struct mounta *uap, struct cred *cr)
180 {
181 mntdata_t *mnt;
182 mntnode_t *mnp;
183 zone_t *zone = curproc->p_zone;
184
185 if (secpolicy_fs_mount(cr, mvp, vfsp) != 0)
186 return (EPERM);
187
188 /*
189 * You can only mount mnttab in your current zone.
190 */
191 if (zone == global_zone) {
192 zone_t *mntzone;
193
194 mntzone = zone_find_by_path(refstr_value(vfsp->vfs_mntpt));
195 ASSERT(mntzone != NULL);
196 zone_rele(mntzone);
197 if (mntzone != zone)
198 return (EBUSY);
199 }
200
201 /*
202 * Having the resource be anything but "mnttab" doesn't make sense
203 */
204 vfs_setresource(vfsp, "mnttab", 0);
205
206 mnt = kmem_zalloc(sizeof (*mnt), KM_SLEEP);
207 mutex_enter(&mvp->v_lock);
208 if ((uap->flags & MS_OVERLAY) == 0 &&
209 (mvp->v_count > 1 || (mvp->v_flag & VROOT))) {
210 mutex_exit(&mvp->v_lock);
211 kmem_free(mnt, sizeof (*mnt));
212 return (EBUSY);
213 }
214 mutex_exit(&mvp->v_lock);
215
216 zone_init_ref(&mnt->mnt_zone_ref);
217 zone_hold_ref(zone, &mnt->mnt_zone_ref, ZONE_REF_MNTFS);
218 mnp = &mnt->mnt_node;
219
220 vfsp->vfs_fstype = mntfstype;
221 vfsp->vfs_data = (caddr_t)mnt;
222 /*
223 * find an available minor device number for this mount.
224 */
225 mutex_enter(&mnt_minor_lock);
226 do {
227 mnt_minor = (mnt_minor + 1) & L_MAXMIN32;
228 vfsp->vfs_dev = makedevice(mnt_major, mnt_minor);
229 } while (vfs_devismounted(vfsp->vfs_dev));
230 mutex_exit(&mnt_minor_lock);
231 vfs_make_fsid(&vfsp->vfs_fsid, vfsp->vfs_dev, mntfstype);
232 vfsp->vfs_bsize = DEV_BSIZE;
233 mntinitrootnode(mnp);
234 MTOV(mnp)->v_vfsp = vfsp;
235 mnp->mnt_mountvp = mvp;
236 vn_exists(MTOV(mnp));
237 return (0);
238 }
239
240 /* ARGSUSED */
241 static int
242 mntunmount(struct vfs *vfsp, int flag, struct cred *cr)
243 {
244 mntdata_t *mnt = (mntdata_t *)vfsp->vfs_data;
245 vnode_t *vp = MTOV(&mnt->mnt_node);
246
247 if (secpolicy_fs_unmount(cr, vfsp) != 0)
248 return (EPERM);
249
250 /*
251 * Ensure that no /mnttab vnodes are in use on this mount point.
252 */
253 mutex_enter(&vp->v_lock);
254 if (vp->v_count > 1 || mnt->mnt_nopen > 0) {
255 mutex_exit(&vp->v_lock);
256 return (EBUSY);
257 }
258
259 mutex_exit(&vp->v_lock);
260 zone_rele_ref(&mnt->mnt_zone_ref, ZONE_REF_MNTFS);
261 vn_invalid(vp);
262 vn_free(vp);
263 kmem_free(mnt, sizeof (*mnt));
264 return (0);
265 }
266
267 /* ARGSUSED */
268 static int
269 mntroot(struct vfs *vfsp, struct vnode **vpp)
270 {
271 mntnode_t *mnp = &((mntdata_t *)vfsp->vfs_data)->mnt_node;
272 struct vnode *vp = MTOV(mnp);
273
274 VN_HOLD(vp);
275 *vpp = vp;
276 return (0);
277 }
278
279 static int
280 mntstatvfs(struct vfs *vfsp, struct statvfs64 *sp)
281 {
282 dev32_t d32;
283
284 bzero((caddr_t)sp, sizeof (*sp));
285 sp->f_bsize = DEV_BSIZE;
286 sp->f_frsize = DEV_BSIZE;
287 sp->f_blocks = (fsblkcnt64_t)0;
288 sp->f_bfree = (fsblkcnt64_t)0;
289 sp->f_bavail = (fsblkcnt64_t)0;
290 sp->f_files = (fsfilcnt64_t)1;
291 sp->f_ffree = (fsfilcnt64_t)0;
292 sp->f_favail = (fsfilcnt64_t)0;
293 (void) cmpldev(&d32, vfsp->vfs_dev);
294 sp->f_fsid = d32;
295 (void) strcpy(sp->f_basetype, vfssw[mntfstype].vsw_name);
296 sp->f_flag = vf_to_stf(vfsp->vfs_flag);
297 sp->f_namemax = 64; /* quite arbitrary */
298 bzero(sp->f_fstr, sizeof (sp->f_fstr));
299 (void) strcpy(sp->f_fstr, "/mnttab");
300 (void) strcpy(&sp->f_fstr[8], "/mnttab");
301 return (0);
302 }