xref: /dragonfly/sys/kern/kern_varsym.c (revision 299d9671) 
1 /*
2  * Copyright (c) 2003,2004 The DragonFly Project.  All rights reserved.
3  *
4  * This code is derived from software contributed to The DragonFly Project
5  * by Matthew Dillon <dillon@backplane.com>
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  *
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
15  *    the documentation and/or other materials provided with the
16  *    distribution.
17  * 3. Neither the name of The DragonFly Project nor the names of its
18  *    contributors may be used to endorse or promote products derived
19  *    from this software without specific, prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  *
34  * $DragonFly: src/sys/kern/kern_varsym.c,v 1.9 2007/04/30 07:18:54 dillon Exp $
35  */
36 
37 /*
38  * This module implements variable storage and management for variant
39  * symlinks.  These variables may also be used for general purposes.
40  */
41 
42 #include <sys/param.h>
43 #include <sys/systm.h>
44 #include <sys/kernel.h>
45 #include <sys/ucred.h>
46 #include <sys/resourcevar.h>
47 #include <sys/proc.h>
48 #include <sys/priv.h>
49 #include <sys/jail.h>
50 #include <sys/queue.h>
51 #include <sys/sysctl.h>
52 #include <sys/malloc.h>
53 #include <sys/varsym.h>
54 #include <sys/sysproto.h>
55 
56 MALLOC_DEFINE(M_VARSYM, "varsym", "variable sets for variant symlinks");
57 
58 struct varsymset	varsymset_sys;
59 
60 /*
61  * Initialize the variant symlink subsystem
62  */
63 static void
64 varsym_sysinit(void *dummy)
65 {
66     varsymset_init(&varsymset_sys, NULL);
67 }
68 SYSINIT(announce, SI_BOOT2_MACHDEP, SI_ORDER_FIRST, varsym_sysinit, NULL);
69 
70 /*
71  * varsymreplace() - called from namei
72  *
73  *	Do variant symlink variable substitution
74  */
75 int
76 varsymreplace(char *cp, int linklen, int maxlen)
77 {
78     int rlen;
79     int xlen;
80     int nlen;
81     int i;
82     varsym_t var;
83 
84     rlen = linklen;
85     while (linklen > 1) {
86 	if (cp[0] == '$' && cp[1] == '{') {
87 	    for (i = 2; i < linklen; ++i) {
88 		if (cp[i] == '}')
89 		    break;
90 	    }
91 	    if (i < linklen &&
92 		(var = varsymfind(VARSYM_ALL_MASK, cp + 2, i - 2)) != NULL
93 	    ) {
94 		xlen = i + 1;			/* bytes to strike */
95 		nlen = strlen(var->vs_data);	/* bytes to add */
96 		if (linklen + nlen - xlen >= maxlen) {
97 		    varsymdrop(var);
98 		    return(-1);
99 		}
100 		KKASSERT(linklen >= xlen);
101 		if (linklen != xlen)
102 		    bcopy(cp + xlen, cp + nlen, linklen - xlen);
103 		bcopy(var->vs_data, cp, nlen);
104 		linklen += nlen - xlen;	/* new relative length */
105 		rlen += nlen - xlen;	/* returned total length */
106 		cp += nlen;		/* adjust past replacement */
107 		linklen -= nlen;	/* adjust past replacement */
108 		maxlen -= nlen;		/* adjust past replacement */
109 	    } else {
110 		/*
111 		 * It's ok if i points to the '}', it will simply be
112 		 * skipped.  i could also have hit linklen.
113 		 */
114 		cp += i;
115 		linklen -= i;
116 		maxlen -= i;
117 	    }
118 	} else {
119 	    ++cp;
120 	    --linklen;
121 	    --maxlen;
122 	}
123     }
124     return(rlen);
125 }
126 
127 /*
128  * varsym_set() system call
129  *
130  * (int level, const char *name, const char *data)
131  */
132 int
133 sys_varsym_set(struct varsym_set_args *uap)
134 {
135     char name[MAXVARSYM_NAME];
136     char *buf;
137     int error;
138 
139     if ((error = copyinstr(uap->name, name, sizeof(name), NULL)) != 0)
140 	goto done2;
141     buf = kmalloc(MAXVARSYM_DATA, M_TEMP, M_WAITOK);
142     if (uap->data &&
143 	(error = copyinstr(uap->data, buf, MAXVARSYM_DATA, NULL)) != 0)
144     {
145 	goto done1;
146     }
147     switch(uap->level) {
148     case VARSYM_SYS:
149 	if (curthread->td_proc != NULL && curthread->td_proc->p_ucred->cr_prison != NULL)
150 	    uap->level = VARSYM_PRISON;
151     case VARSYM_PRISON:
152 	if (curthread->td_proc != NULL &&
153 	    (error = priv_check_cred(curthread->td_proc->p_ucred, PRIV_ROOT, PRISON_ROOT)) != 0)
154 	    break;
155 	/* fall through */
156     case VARSYM_USER:
157 	/* XXX check jail / implement per-jail user */
158 	/* fall through */
159     case VARSYM_PROC:
160 	if (uap->data) {
161 	    (void)varsymmake(uap->level, name, NULL);
162 	    error = varsymmake(uap->level, name, buf);
163 	} else {
164 	    error = varsymmake(uap->level, name, NULL);
165 	}
166 	break;
167     }
168 done1:
169     kfree(buf, M_TEMP);
170 done2:
171     return(error);
172 }
173 
174 /*
175  * varsym_get() system call
176  *
177  * (int mask, const char *wild, char *buf, int bufsize)
178  */
179 int
180 sys_varsym_get(struct varsym_get_args *uap)
181 {
182     char wild[MAXVARSYM_NAME];
183     varsym_t sym;
184     int error;
185     int dlen;
186 
187     if ((error = copyinstr(uap->wild, wild, sizeof(wild), NULL)) != 0)
188 	goto done;
189     sym = varsymfind(uap->mask, wild, strlen(wild));
190     if (sym == NULL) {
191 	error = ENOENT;
192 	goto done;
193     }
194     dlen = strlen(sym->vs_data);
195     if (dlen < uap->bufsize) {
196 	copyout(sym->vs_data, uap->buf, dlen + 1);
197     } else if (uap->bufsize) {
198 	copyout("", uap->buf, 1);
199     }
200     uap->sysmsg_result = dlen + 1;
201     varsymdrop(sym);
202 done:
203     return(error);
204 }
205 
206 /*
207  * varsym_list() system call
208  *
209  * (int level, char *buf, int maxsize, int *marker)
210  */
211 int
212 sys_varsym_list(struct varsym_list_args *uap)
213 {
214 	struct varsymset *vss;
215 	struct varsyment *ve;
216 	struct proc *p;
217 	int i;
218 	int error;
219 	int bytes;
220 	int earlyterm;
221 	int marker;
222 
223 	/*
224 	 * Get the marker from userspace.
225 	 */
226 	if ((error = copyin(uap->marker, &marker, sizeof(marker))) != 0)
227 		goto done;
228 
229 	/*
230 	 * Figure out the varsym set.
231 	 */
232 	p = curproc;
233 	vss = NULL;
234 
235 	switch (uap->level) {
236 	case VARSYM_PROC:
237 		if (p)
238 			vss = &p->p_varsymset;
239 		break;
240 	case VARSYM_USER:
241 		if (p)
242 			vss = &p->p_ucred->cr_uidinfo->ui_varsymset;
243 		break;
244 	case VARSYM_SYS:
245 		vss = &varsymset_sys;
246 		break;
247 	case VARSYM_PRISON:
248 		if (p != NULL && p->p_ucred->cr_prison != NULL)
249 			vss = &p->p_ucred->cr_prison->pr_varsymset;
250 		break;
251 	}
252 	if (vss == NULL) {
253 		error = EINVAL;
254 		goto done;
255 	}
256 
257 	/*
258 	 * Loop through the variables and dump them to uap->buf
259 	 */
260 	i = 0;
261 	bytes = 0;
262 	earlyterm = 0;
263 
264 	TAILQ_FOREACH(ve, &vss->vx_queue, ve_entry) {
265 		varsym_t sym = ve->ve_sym;
266 		int namelen = strlen(sym->vs_name);
267 		int datalen = strlen(sym->vs_data);
268 		int totlen = namelen + datalen + 2;
269 
270 		/*
271 		 * Skip to our index point
272 		 */
273 		if (i < marker) {
274 			++i;
275 			continue;
276 		}
277 
278 		/*
279 		 * Stop if there is insufficient space in the user buffer.
280 		 * If we haven't stored anything yet return EOVERFLOW.
281 		 * Note that the marker index (i) does not change.
282 		 */
283 		if (bytes + totlen > uap->maxsize) {
284 			if (bytes == 0)
285 				error = EOVERFLOW;
286 			earlyterm = 1;
287 			break;
288 		}
289 
290 		error = copyout(sym->vs_name, uap->buf + bytes, namelen + 1);
291 		if (error == 0) {
292 			bytes += namelen + 1;
293 			error = copyout(sym->vs_data, uap->buf + bytes, datalen + 1);
294 			if (error == 0)
295 				bytes += datalen + 1;
296 			else
297 				bytes -= namelen + 1;	/* revert if error */
298 		}
299 		if (error) {
300 			earlyterm = 1;
301 			break;
302 		}
303 		++i;
304 	}
305 
306 	/*
307 	 * Save the marker back.  If no error occured and earlyterm is clear
308 	 * the marker is set to -1 indicating that the variable list has been
309 	 * exhausted.  If no error occured the number of bytes loaded into
310 	 * the buffer will be returned, otherwise the syscall code returns -1.
311 	 */
312 	if (error == 0 && earlyterm == 0)
313 		marker = -1;
314 	else
315 		marker = i;
316 	if (error == 0)
317 		error = copyout(&marker, uap->marker, sizeof(marker));
318 	uap->sysmsg_result = bytes;
319 done:
320 	return(error);
321 }
322 
323 /*
324  * Lookup a variant symlink.  XXX use a hash table.
325  */
326 static
327 struct varsyment *
328 varsymlookup(struct varsymset *vss, const char *name, int namelen)
329 {
330     struct varsyment *ve;
331 
332     TAILQ_FOREACH(ve, &vss->vx_queue, ve_entry) {
333 	varsym_t var = ve->ve_sym;
334 	if (var->vs_namelen == namelen &&
335 	    bcmp(name, var->vs_name, namelen) == 0
336 	) {
337 	    return(ve);
338 	}
339     }
340     return(NULL);
341 }
342 
343 varsym_t
344 varsymfind(int mask, const char *name, int namelen)
345 {
346     struct proc *p = curproc;
347     struct varsyment *ve = NULL;
348     varsym_t sym;
349 
350     if ((mask & (VARSYM_PROC_MASK|VARSYM_USER_MASK)) && p != NULL) {
351 	if (mask & VARSYM_PROC_MASK)
352 	    ve = varsymlookup(&p->p_varsymset, name, namelen);
353 	if (ve == NULL && (mask & VARSYM_USER_MASK))
354 	    ve = varsymlookup(&p->p_ucred->cr_uidinfo->ui_varsymset, name, namelen);
355     }
356     if (ve == NULL && (mask & VARSYM_SYS_MASK)) {
357 	if (p != NULL && p->p_ucred->cr_prison)
358 	    ve = varsymlookup(&p->p_ucred->cr_prison->pr_varsymset, name, namelen);
359 	else
360 	    ve = varsymlookup(&varsymset_sys, name, namelen);
361     }
362     if (ve) {
363 	sym = ve->ve_sym;
364 	++sym->vs_refs;
365 	return(sym);
366     } else {
367 	return(NULL);
368     }
369 }
370 
371 int
372 varsymmake(int level, const char *name, const char *data)
373 {
374     struct varsymset *vss = NULL;
375     struct varsyment *ve;
376     struct proc *p = curproc;
377     varsym_t sym;
378     int namelen = strlen(name);
379     int datalen;
380     int error;
381 
382     switch(level) {
383     case VARSYM_PROC:
384 	if (p)
385 	    vss = &p->p_varsymset;
386 	break;
387     case VARSYM_USER:
388 	if (p)
389 	    vss = &p->p_ucred->cr_uidinfo->ui_varsymset;
390 	break;
391     case VARSYM_SYS:
392 	vss = &varsymset_sys;
393 	break;
394     case VARSYM_PRISON:
395 	if (p != NULL && p->p_ucred->cr_prison != NULL)
396 	    vss = &p->p_ucred->cr_prison->pr_varsymset;
397 	break;
398     }
399     if (vss == NULL) {
400 	error = EINVAL;
401     } else if (data && vss->vx_setsize >= MAXVARSYM_SET) {
402 	error = E2BIG;
403     } else if (data) {
404 	datalen = strlen(data);
405 	ve = kmalloc(sizeof(struct varsyment), M_VARSYM, M_WAITOK|M_ZERO);
406 	sym = kmalloc(sizeof(struct varsym) + namelen + datalen + 2, M_VARSYM, M_WAITOK);
407 	ve->ve_sym = sym;
408 	sym->vs_refs = 1;
409 	sym->vs_namelen = namelen;
410 	sym->vs_name = (char *)(sym + 1);
411 	sym->vs_data = sym->vs_name + namelen + 1;
412 	strcpy(sym->vs_name, name);
413 	strcpy(sym->vs_data, data);
414 	TAILQ_INSERT_TAIL(&vss->vx_queue, ve, ve_entry);
415 	vss->vx_setsize += sizeof(struct varsyment) + sizeof(struct varsym) + namelen + datalen + 8;
416 	error = 0;
417     } else {
418 	if ((ve = varsymlookup(vss, name, namelen)) != NULL) {
419 	    TAILQ_REMOVE(&vss->vx_queue, ve, ve_entry);
420 	    vss->vx_setsize -= sizeof(struct varsyment) + sizeof(struct varsym) + namelen + strlen(ve->ve_sym->vs_data) + 8;
421 	    varsymdrop(ve->ve_sym);
422 	    kfree(ve, M_VARSYM);
423 	    error = 0;
424 	} else {
425 	    error = ENOENT;
426 	}
427     }
428     return(error);
429 }
430 
431 void
432 varsymdrop(varsym_t sym)
433 {
434     KKASSERT(sym->vs_refs > 0);
435     if (--sym->vs_refs == 0) {
436 	kfree(sym, M_VARSYM);
437     }
438 }
439 
440 static void
441 varsymdup(struct varsymset *vss, struct varsyment *ve)
442 {
443     struct varsyment *nve;
444 
445     nve = kmalloc(sizeof(struct varsyment), M_VARSYM, M_WAITOK|M_ZERO);
446     nve->ve_sym = ve->ve_sym;
447     ++nve->ve_sym->vs_refs;
448     TAILQ_INSERT_TAIL(&vss->vx_queue, nve, ve_entry);
449 }
450 
451 void
452 varsymset_init(struct varsymset *vss, struct varsymset *copy)
453 {
454     struct varsyment *ve;
455 
456     TAILQ_INIT(&vss->vx_queue);
457     if (copy) {
458 	TAILQ_FOREACH(ve, &copy->vx_queue, ve_entry) {
459 	    varsymdup(vss, ve);
460 	}
461 	vss->vx_setsize = copy->vx_setsize;
462     }
463 }
464 
465 void
466 varsymset_clean(struct varsymset *vss)
467 {
468     struct varsyment *ve;
469 
470     while ((ve = TAILQ_FIRST(&vss->vx_queue)) != NULL) {
471 	TAILQ_REMOVE(&vss->vx_queue, ve, ve_entry);
472 	varsymdrop(ve->ve_sym);
473 	kfree(ve, M_VARSYM);
474     }
475     vss->vx_setsize = 0;
476 }
477 
478