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 int
101 devpts_validate(struct sdev_node *dv)
102 {
103 minor_t min;
104 uid_t uid;
105 gid_t gid;
106 timestruc_t now;
107 char *nm = dv->sdev_name;
108
109 ASSERT(dv->sdev_state == SDEV_READY);
110
111 /* validate only READY nodes */
112 if (dv->sdev_state != SDEV_READY) {
113 sdcmn_err(("dev fs: skipping: node not ready %s(%p)",
114 nm, (void *)dv));
115 return (SDEV_VTOR_SKIP);
116 }
117
118 if (devpts_strtol(nm, &min) != 0) {
119 sdcmn_err7(("devpts_validate: not a valid minor: %s\n", nm));
120 return (SDEV_VTOR_INVALID);
121 }
122
123 /*
124 * Check if pts driver is attached
125 */
126 if (ptms_subsidiary_attached() == (major_t)-1) {
127 sdcmn_err7(("devpts_validate: subsidiary not attached\n"));
128 return (SDEV_VTOR_INVALID);
129 }
130
131 if (ptms_minor_valid(min, &uid, &gid) == 0) {
132 if (ptms_minor_exists(min)) {
133 sdcmn_err7(("devpts_validate: valid in different zone "
134 "%s\n", nm));
135 return (SDEV_VTOR_SKIP);
136 } else {
137 sdcmn_err7(("devpts_validate: %s not valid pty\n",
138 nm));
139 return (SDEV_VTOR_INVALID);
140 }
141 }
142
143 ASSERT(dv->sdev_attr);
144 if (dv->sdev_attr->va_uid != uid || dv->sdev_attr->va_gid != gid) {
145 dv->sdev_attr->va_uid = uid;
146 dv->sdev_attr->va_gid = gid;
147 gethrestime(&now);
148 dv->sdev_attr->va_atime = now;
149 dv->sdev_attr->va_mtime = now;
150 dv->sdev_attr->va_ctime = now;
151 sdcmn_err7(("devpts_validate: update uid/gid/times%s\n", nm));
152 }
153
154 return (SDEV_VTOR_VALID);
155 }
156
157 /*
158 * This callback is invoked from devname_lookup_func() to create
159 * a pts entry when the node is not found in the cache.
160 */
161 static int
162 devpts_create_rvp(struct sdev_node *ddv, char *nm,
163 void **arg, cred_t *cred, void *whatever, char *whichever)
164 {
165 minor_t min;
166 major_t maj;
167 uid_t uid;
168 gid_t gid;
169 timestruc_t now;
170 struct vattr *vap = (struct vattr *)arg;
171
172 if (devpts_strtol(nm, &min) != 0) {
173 sdcmn_err7(("devpts_create_rvp: not a valid minor: %s\n", nm));
174 return (-1);
175 }
176
177 /*
178 * Check if pts driver is attached and if it is get the major number.
179 */
180 maj = ptms_subsidiary_attached();
181 if (maj == (major_t)-1) {
182 sdcmn_err7(("devpts_create_rvp: subsidiary not attached\n"));
183 return (-1);
184 }
185
186 /*
187 * Only allow creation of ptys allocated to our zone
188 */
189 if (!ptms_minor_valid(min, &uid, &gid)) {
190 sdcmn_err7(("devpts_create_rvp: %s not valid pty"
191 "or not valid in this zone\n", nm));
192 return (-1);
193 }
194
195
196 /*
197 * This is a valid pty (at least at this point in time).
198 * Create the node by setting the attribute. The rest
199 * is taken care of by devname_lookup_func().
200 */
201 *vap = devpts_vattr;
202 vap->va_rdev = makedevice(maj, min);
203 vap->va_uid = uid;
204 vap->va_gid = gid;
205 gethrestime(&now);
206 vap->va_atime = now;
207 vap->va_mtime = now;
208 vap->va_ctime = now;
209
210 return (0);
211 }
212
213 /*
214 * Clean pts sdev_nodes that are no longer valid.
215 */
216 static void
217 devpts_prunedir(struct sdev_node *ddv)
218 {
219 struct vnode *vp;
220 struct sdev_node *dv, *next = NULL;
221 int (*vtor)(struct sdev_node *) = NULL;
222
223 ASSERT(ddv->sdev_flags & SDEV_VTOR);
224
225 vtor = (int (*)(struct sdev_node *))sdev_get_vtor(ddv);
226 ASSERT(vtor);
227
228 if (rw_tryupgrade(&ddv->sdev_contents) == 0) {
229 rw_exit(&ddv->sdev_contents);
230 rw_enter(&ddv->sdev_contents, RW_WRITER);
231 }
232
233 for (dv = SDEV_FIRST_ENTRY(ddv); dv; dv = next) {
234 next = SDEV_NEXT_ENTRY(ddv, dv);
235
236 /* validate and prune only ready nodes */
237 if (dv->sdev_state != SDEV_READY)
238 continue;
239
240 switch (vtor(dv)) {
241 case SDEV_VTOR_VALID:
242 case SDEV_VTOR_SKIP:
243 continue;
244 case SDEV_VTOR_INVALID:
245 case SDEV_VTOR_STALE:
246 sdcmn_err7(("prunedir: destroy invalid "
247 "node: %s(%p)\n", dv->sdev_name, (void *)dv));
248 break;
249 }
250 vp = SDEVTOV(dv);
251 if (vp->v_count > 0)
252 continue;
253 SDEV_HOLD(dv);
254 /* remove the cache node */
255 (void) sdev_cache_update(ddv, &dv, dv->sdev_name,
256 SDEV_CACHE_DELETE);
257 SDEV_RELE(dv);
258 }
259 rw_downgrade(&ddv->sdev_contents);
260 }
261
262 /*
263 * Lookup for /dev/pts directory
264 * If the entry does not exist, the devpts_create_rvp() callback
265 * is invoked to create it. Nodes do not persist across reboot.
266 *
267 * There is a potential denial of service here via
268 * fattach on top of a /dev/pts node - any permission changes
269 * applied to the node, apply to the fattached file and not
270 * to the underlying pts node. As a result when the previous
271 * user fdetaches, the pts node is still owned by the previous
272 * owner. To prevent this we don't allow fattach() on top of a pts
273 * node. This is done by a modification in the namefs filesystem
274 * where we check if the underlying node has the /dev/pts vnodeops.
275 * We do this via VOP_REALVP() on the underlying specfs node.
276 * sdev_nodes currently don't have a realvp. If a realvp is ever
277 * created for sdev_nodes, then VOP_REALVP() will return the
278 * actual realvp (possibly a ufs vnode). This will defeat the check
279 * in namefs code which checks if VOP_REALVP() returns a devpts
280 * node. We add an ASSERT here in /dev/pts lookup() to check for
281 * this condition. If sdev_nodes ever get a VOP_REALVP() entry point,
282 * change the code in the namefs filesystem code (in nm_mount()) to
283 * access the realvp of the specfs node directly instead of using
284 * VOP_REALVP().
285 */
286 static int
287 devpts_lookup(struct vnode *dvp, char *nm, struct vnode **vpp,
288 struct pathname *pnp, int flags, struct vnode *rdir, struct cred *cred,
289 caller_context_t *ct, int *direntflags, pathname_t *realpnp)
290 {
291 struct sdev_node *sdvp = VTOSDEV(dvp);
292 struct sdev_node *dv;
293 struct vnode *rvp = NULL;
294 int error;
295
296 error = devname_lookup_func(sdvp, nm, vpp, cred, devpts_create_rvp,
297 SDEV_VATTR);
298
299 if (error == 0) {
300 switch ((*vpp)->v_type) {
301 case VCHR:
302 dv = VTOSDEV(VTOS(*vpp)->s_realvp);
303 ASSERT(VOP_REALVP(SDEVTOV(dv), &rvp, NULL) == ENOSYS);
304 break;
305 case VDIR:
306 dv = VTOSDEV(*vpp);
307 break;
308 default:
309 cmn_err(CE_PANIC, "devpts_lookup: Unsupported node "
310 "type: %p: %d", (void *)(*vpp), (*vpp)->v_type);
311 break;
312 }
313 ASSERT(SDEV_HELD(dv));
314 }
315
316 return (error);
317 }
318
319 /*
320 * We allow create to find existing nodes
321 * - if the node doesn't exist - EROFS
322 * - creating an existing dir read-only succeeds, otherwise EISDIR
323 * - exclusive creates fail - EEXIST
324 */
325 static int
326 devpts_create(struct vnode *dvp, char *nm, struct vattr *vap, vcexcl_t excl,
327 int mode, struct vnode **vpp, struct cred *cred, int flag,
328 caller_context_t *ct, vsecattr_t *vsecp)
329 {
330 int error;
331 struct vnode *vp;
332
333 *vpp = NULL;
334
335 error = devpts_lookup(dvp, nm, &vp, NULL, 0, NULL, cred, ct, NULL,
336 NULL);
337 if (error == 0) {
338 if (excl == EXCL)
339 error = EEXIST;
340 else if (vp->v_type == VDIR && (mode & VWRITE))
341 error = EISDIR;
342 else
343 error = VOP_ACCESS(vp, mode, 0, cred, ct);
344
345 if (error) {
346 VN_RELE(vp);
347 } else
348 *vpp = vp;
349 } else if (error == ENOENT) {
350 error = EROFS;
351 }
352
353 return (error);
354 }
355
356 /*
357 * Display all instantiated pts (subsidiary) device nodes.
358 * A /dev/pts entry will be created only after the first lookup of the
359 * subsidiary device succeeds.
360 */
361 static int
362 devpts_readdir(struct vnode *dvp, struct uio *uiop, struct cred *cred,
363 int *eofp, caller_context_t *ct, int flags)
364 {
365 struct sdev_node *sdvp = VTOSDEV(dvp);
366 if (uiop->uio_offset == 0) {
367 devpts_prunedir(sdvp);
368 }
369
370 return (devname_readdir_func(dvp, uiop, cred, eofp, 0));
371 }
372
373
374 static int
375 devpts_set_id(struct sdev_node *dv, struct vattr *vap, int protocol)
376 {
377 ASSERT((protocol & AT_UID) || (protocol & AT_GID));
378 ptms_set_owner(getminor(SDEVTOV(dv)->v_rdev),
379 vap->va_uid, vap->va_gid);
380 return (0);
381
382 }
383
384 static int
385 devpts_setattr(struct vnode *vp, struct vattr *vap, int flags,
386 struct cred *cred, caller_context_t *ctp)
387 {
388 ASSERT((vp->v_type == VCHR) || (vp->v_type == VDIR));
389 return (devname_setattr_func(vp, vap, flags, cred,
390 devpts_set_id, AT_UID|AT_GID));
391 }
392
393
394 /*
395 * We override lookup and readdir to build entries based on the
396 * in kernel pty table. Also override setattr/setsecattr to
397 * avoid persisting permissions.
398 */
399 const fs_operation_def_t devpts_vnodeops_tbl[] = {
400 VOPNAME_READDIR, { .vop_readdir = devpts_readdir },
401 VOPNAME_LOOKUP, { .vop_lookup = devpts_lookup },
402 VOPNAME_CREATE, { .vop_create = devpts_create },
403 VOPNAME_SETATTR, { .vop_setattr = devpts_setattr },
404 VOPNAME_REMOVE, { .error = fs_nosys },
405 VOPNAME_MKDIR, { .error = fs_nosys },
406 VOPNAME_RMDIR, { .error = fs_nosys },
407 VOPNAME_SYMLINK, { .error = fs_nosys },
408 VOPNAME_SETSECATTR, { .error = fs_nosys },
409 NULL, NULL
410 };