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 2008 Sun Microsystems, Inc. All rights reserved.
23 * Use is subject to license terms.
24 */
25
26 /*
27 * vnode ops for the /dev/pts directory
28 * The lookup is based on the internal pty table. We also
29 * override readdir in order to delete pts nodes no longer
30 * in use.
31 */
32
33 #include <sys/types.h>
34 #include <sys/param.h>
35 #include <sys/sysmacros.h>
36 #include <sys/sunndi.h>
37 #include <fs/fs_subr.h>
38 #include <sys/fs/dv_node.h>
39 #include <sys/fs/sdev_impl.h>
40 #include <sys/policy.h>
41 #include <sys/ptms.h>
42 #include <sys/stat.h>
43 #include <sys/vfs_opreg.h>
44
45 #define DEVPTS_UID_DEFAULT 0
46 #define DEVPTS_GID_DEFAULT 3
47 #define DEVPTS_DEVMODE_DEFAULT (0620)
48
49 #define isdigit(ch) ((ch) >= '0' && (ch) <= '9')
50
51 static vattr_t devpts_vattr = {
52 AT_TYPE|AT_MODE|AT_UID|AT_GID, /* va_mask */
53 VCHR, /* va_type */
54 S_IFCHR | DEVPTS_DEVMODE_DEFAULT, /* va_mode */
55 DEVPTS_UID_DEFAULT, /* va_uid */
56 DEVPTS_GID_DEFAULT, /* va_gid */
57 0 /* 0 hereafter */
58 };
59
60 struct vnodeops *devpts_vnodeops;
61
62 struct vnodeops *
63 devpts_getvnodeops(void)
64 {
65 return (devpts_vnodeops);
66 }
67
68 /*
69 * Convert string to minor number. Some care must be taken
70 * as we are processing user input. Catch cases like
71 * /dev/pts/4foo and /dev/pts/-1
72 */
73 static int
74 devpts_strtol(const char *nm, minor_t *mp)
75 {
76 long uminor = 0;
77 char *endptr = NULL;
78
79 if (nm == NULL || !isdigit(*nm))
80 return (EINVAL);
81
82 *mp = 0;
83 if (ddi_strtol(nm, &endptr, 10, &uminor) != 0 ||
84 *endptr != '\0' || uminor < 0) {
85 return (EINVAL);
86 }
87
88 *mp = (minor_t)uminor;
89 return (0);
90 }
91
92 /*
93 * Check if a pts sdev_node is still valid - i.e. it represents a current pty.
94 * This serves two purposes
95 * - only valid pts nodes are returned during lookup() and readdir().
96 * - since pts sdev_nodes are not actively destroyed when a pty goes
97 * away, we use the validator to do deferred cleanup i.e. when such
98 * nodes are encountered during subsequent lookup() and readdir().
99 */
100 /*ARGSUSED*/
101 int
102 devpts_validate(struct sdev_node *dv)
103 {
104 minor_t min;
105 uid_t uid;
106 gid_t gid;
107 timestruc_t now;
108 char *nm = dv->sdev_name;
109
110 ASSERT(dv->sdev_state == SDEV_READY);
111
112 /* validate only READY nodes */
113 if (dv->sdev_state != SDEV_READY) {
114 sdcmn_err(("dev fs: skipping: node not ready %s(%p)",
115 nm, (void *)dv));
116 return (SDEV_VTOR_SKIP);
117 }
118
119 if (devpts_strtol(nm, &min) != 0) {
120 sdcmn_err7(("devpts_validate: not a valid minor: %s\n", nm));
121 return (SDEV_VTOR_INVALID);
122 }
123
124 /*
125 * Check if pts driver is attached
126 */
127 if (ptms_slave_attached() == (major_t)-1) {
128 sdcmn_err7(("devpts_validate: slave not attached\n"));
129 return (SDEV_VTOR_INVALID);
130 }
131
132 if (ptms_minor_valid(min, &uid, &gid) == 0) {
133 if (ptms_minor_exists(min)) {
134 sdcmn_err7(("devpts_validate: valid in different zone "
135 "%s\n", nm));
136 return (SDEV_VTOR_SKIP);
137 } else {
138 sdcmn_err7(("devpts_validate: %s not valid pty\n",
139 nm));
140 return (SDEV_VTOR_INVALID);
141 }
142 }
143
144 ASSERT(dv->sdev_attr);
145 if (dv->sdev_attr->va_uid != uid || dv->sdev_attr->va_gid != gid) {
146 dv->sdev_attr->va_uid = uid;
147 dv->sdev_attr->va_gid = gid;
148 gethrestime(&now);
149 dv->sdev_attr->va_atime = now;
150 dv->sdev_attr->va_mtime = now;
151 dv->sdev_attr->va_ctime = now;
152 sdcmn_err7(("devpts_validate: update uid/gid/times%s\n", nm));
153 }
154
155 return (SDEV_VTOR_VALID);
156 }
157
158 /*
159 * This callback is invoked from devname_lookup_func() to create
160 * a pts entry when the node is not found in the cache.
161 */
162 /*ARGSUSED*/
163 static int
164 devpts_create_rvp(struct sdev_node *ddv, char *nm,
165 void **arg, cred_t *cred, void *whatever, char *whichever)
166 {
167 minor_t min;
168 major_t maj;
169 uid_t uid;
170 gid_t gid;
171 timestruc_t now;
172 struct vattr *vap = (struct vattr *)arg;
173
174 if (devpts_strtol(nm, &min) != 0) {
175 sdcmn_err7(("devpts_create_rvp: not a valid minor: %s\n", nm));
176 return (-1);
177 }
178
179 /*
180 * Check if pts driver is attached and if it is
181 * get the major number.
182 */
183 maj = ptms_slave_attached();
184 if (maj == (major_t)-1) {
185 sdcmn_err7(("devpts_create_rvp: slave not attached\n"));
186 return (-1);
187 }
188
189 /*
190 * Only allow creation of ptys allocated to our zone
191 */
192 if (!ptms_minor_valid(min, &uid, &gid)) {
193 sdcmn_err7(("devpts_create_rvp: %s not valid pty"
194 "or not valid in this zone\n", nm));
195 return (-1);
196 }
197
198
199 /*
200 * This is a valid pty (at least at this point in time).
201 * Create the node by setting the attribute. The rest
202 * is taken care of by devname_lookup_func().
203 */
204 *vap = devpts_vattr;
205 vap->va_rdev = makedevice(maj, min);
206 vap->va_uid = uid;
207 vap->va_gid = gid;
208 gethrestime(&now);
209 vap->va_atime = now;
210 vap->va_mtime = now;
211 vap->va_ctime = now;
212
213 return (0);
214 }
215
216 /*
217 * Clean pts sdev_nodes that are no longer valid.
218 */
219 static void
220 devpts_prunedir(struct sdev_node *ddv)
221 {
222 struct vnode *vp;
223 struct sdev_node *dv, *next = NULL;
224 int (*vtor)(struct sdev_node *) = NULL;
225
226 ASSERT(ddv->sdev_flags & SDEV_VTOR);
227
228 vtor = (int (*)(struct sdev_node *))sdev_get_vtor(ddv);
229 ASSERT(vtor);
230
231 if (rw_tryupgrade(&ddv->sdev_contents) == NULL) {
232 rw_exit(&ddv->sdev_contents);
233 rw_enter(&ddv->sdev_contents, RW_WRITER);
234 }
235
236 for (dv = SDEV_FIRST_ENTRY(ddv); dv; dv = next) {
237 next = SDEV_NEXT_ENTRY(ddv, dv);
238
239 /* validate and prune only ready nodes */
240 if (dv->sdev_state != SDEV_READY)
241 continue;
242
243 switch (vtor(dv)) {
244 case SDEV_VTOR_VALID:
245 case SDEV_VTOR_SKIP:
246 continue;
247 case SDEV_VTOR_INVALID:
248 case SDEV_VTOR_STALE:
249 sdcmn_err7(("prunedir: destroy invalid "
250 "node: %s(%p)\n", dv->sdev_name, (void *)dv));
251 break;
252 }
253 vp = SDEVTOV(dv);
254 if (vp->v_count > 0)
255 continue;
256 SDEV_HOLD(dv);
257 /* remove the cache node */
258 (void) sdev_cache_update(ddv, &dv, dv->sdev_name,
259 SDEV_CACHE_DELETE);
260 SDEV_RELE(dv);
261 }
262 rw_downgrade(&ddv->sdev_contents);
263 }
264
265 /*
266 * Lookup for /dev/pts directory
267 * If the entry does not exist, the devpts_create_rvp() callback
268 * is invoked to create it. Nodes do not persist across reboot.
269 *
270 * There is a potential denial of service here via
271 * fattach on top of a /dev/pts node - any permission changes
272 * applied to the node, apply to the fattached file and not
273 * to the underlying pts node. As a result when the previous
274 * user fdetaches, the pts node is still owned by the previous
275 * owner. To prevent this we don't allow fattach() on top of a pts
276 * node. This is done by a modification in the namefs filesystem
277 * where we check if the underlying node has the /dev/pts vnodeops.
278 * We do this via VOP_REALVP() on the underlying specfs node.
279 * sdev_nodes currently don't have a realvp. If a realvp is ever
280 * created for sdev_nodes, then VOP_REALVP() will return the
281 * actual realvp (possibly a ufs vnode). This will defeat the check
282 * in namefs code which checks if VOP_REALVP() returns a devpts
283 * node. We add an ASSERT here in /dev/pts lookup() to check for
284 * this condition. If sdev_nodes ever get a VOP_REALVP() entry point,
285 * change the code in the namefs filesystem code (in nm_mount()) to
286 * access the realvp of the specfs node directly instead of using
287 * VOP_REALVP().
288 */
289 /*ARGSUSED3*/
290 static int
291 devpts_lookup(struct vnode *dvp, char *nm, struct vnode **vpp,
292 struct pathname *pnp, int flags, struct vnode *rdir, struct cred *cred,
293 caller_context_t *ct, int *direntflags, pathname_t *realpnp)
294 {
295 struct sdev_node *sdvp = VTOSDEV(dvp);
296 struct sdev_node *dv;
297 struct vnode *rvp = NULL;
298 int error;
299
300 error = devname_lookup_func(sdvp, nm, vpp, cred, devpts_create_rvp,
301 SDEV_VATTR);
302
303 if (error == 0) {
304 switch ((*vpp)->v_type) {
305 case VCHR:
306 dv = VTOSDEV(VTOS(*vpp)->s_realvp);
307 ASSERT(VOP_REALVP(SDEVTOV(dv), &rvp, NULL) == ENOSYS);
308 break;
309 case VDIR:
310 dv = VTOSDEV(*vpp);
311 break;
312 default:
313 cmn_err(CE_PANIC, "devpts_lookup: Unsupported node "
314 "type: %p: %d", (void *)(*vpp), (*vpp)->v_type);
315 break;
316 }
317 ASSERT(SDEV_HELD(dv));
318 }
319
320 return (error);
321 }
322
323 /*
324 * We allow create to find existing nodes
325 * - if the node doesn't exist - EROFS
326 * - creating an existing dir read-only succeeds, otherwise EISDIR
327 * - exclusive creates fail - EEXIST
328 */
329 /*ARGSUSED2*/
330 static int
331 devpts_create(struct vnode *dvp, char *nm, struct vattr *vap, vcexcl_t excl,
332 int mode, struct vnode **vpp, struct cred *cred, int flag,
333 caller_context_t *ct, vsecattr_t *vsecp)
334 {
335 int error;
336 struct vnode *vp;
337
338 *vpp = NULL;
339
340 error = devpts_lookup(dvp, nm, &vp, NULL, 0, NULL, cred, ct, NULL,
341 NULL);
342 if (error == 0) {
343 if (excl == EXCL)
344 error = EEXIST;
345 else if (vp->v_type == VDIR && (mode & VWRITE))
346 error = EISDIR;
347 else
348 error = VOP_ACCESS(vp, mode, 0, cred, ct);
349
350 if (error) {
351 VN_RELE(vp);
352 } else
353 *vpp = vp;
354 } else if (error == ENOENT) {
355 error = EROFS;
356 }
357
358 return (error);
359 }
360
361 /*
362 * Display all instantiated pts (slave) device nodes.
363 * A /dev/pts entry will be created only after the first lookup of the slave
364 * device succeeds.
365 */
366 /*ARGSUSED4*/
367 static int
368 devpts_readdir(struct vnode *dvp, struct uio *uiop, struct cred *cred,
369 int *eofp, caller_context_t *ct, int flags)
370 {
371 struct sdev_node *sdvp = VTOSDEV(dvp);
372 if (uiop->uio_offset == 0) {
373 devpts_prunedir(sdvp);
374 }
375
376 return (devname_readdir_func(dvp, uiop, cred, eofp, 0));
377 }
378
379
380 static int
381 devpts_set_id(struct sdev_node *dv, struct vattr *vap, int protocol)
382 {
383 ASSERT((protocol & AT_UID) || (protocol & AT_GID));
384 ptms_set_owner(getminor(SDEVTOV(dv)->v_rdev),
385 vap->va_uid, vap->va_gid);
386 return (0);
387
388 }
389
390 /*ARGSUSED4*/
391 static int
392 devpts_setattr(struct vnode *vp, struct vattr *vap, int flags,
393 struct cred *cred, caller_context_t *ctp)
394 {
395 ASSERT((vp->v_type == VCHR) || (vp->v_type == VDIR));
396 return (devname_setattr_func(vp, vap, flags, cred,
397 devpts_set_id, AT_UID|AT_GID));
398 }
399
400
401 /*
402 * We override lookup and readdir to build entries based on the
403 * in kernel pty table. Also override setattr/setsecattr to
404 * avoid persisting permissions.
405 */
406 const fs_operation_def_t devpts_vnodeops_tbl[] = {
407 VOPNAME_READDIR, { .vop_readdir = devpts_readdir },
408 VOPNAME_LOOKUP, { .vop_lookup = devpts_lookup },
409 VOPNAME_CREATE, { .vop_create = devpts_create },
410 VOPNAME_SETATTR, { .vop_setattr = devpts_setattr },
411 VOPNAME_REMOVE, { .error = fs_nosys },
412 VOPNAME_MKDIR, { .error = fs_nosys },
413 VOPNAME_RMDIR, { .error = fs_nosys },
414 VOPNAME_SYMLINK, { .error = fs_nosys },
415 VOPNAME_SETSECATTR, { .error = fs_nosys },
416 NULL, NULL
417 };