1/* $OpenBSD: ssh-pkcs11.c,v 1.8 2013/07/12 00:20:00 djm Exp $ */
2/*
3 * Copyright (c) 2010 Markus Friedl.  All rights reserved.
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18#include "includes.h"
19
20#ifdef ENABLE_PKCS11
21
22#include <sys/types.h>
23#ifdef HAVE_SYS_TIME_H
24# include <sys/time.h>
25#endif
26#include <stdarg.h>
27#include <stdio.h>
28
29#include <string.h>
30#include <dlfcn.h>
31
32#include "openbsd-compat/sys-queue.h"
33
34#define CRYPTOKI_COMPAT
35#include "pkcs11.h"
36
37#include "log.h"
38#include "misc.h"
39#include "key.h"
40#include "ssh-pkcs11.h"
41#include "xmalloc.h"
42
43struct pkcs11_slotinfo {
44	CK_TOKEN_INFO		token;
45	CK_SESSION_HANDLE	session;
46	int			logged_in;
47};
48
49struct pkcs11_provider {
50	char			*name;
51	void			*handle;
52	CK_FUNCTION_LIST	*function_list;
53	CK_INFO			info;
54	CK_ULONG		nslots;
55	CK_SLOT_ID		*slotlist;
56	struct pkcs11_slotinfo	*slotinfo;
57	int			valid;
58	int			refcount;
59	TAILQ_ENTRY(pkcs11_provider) next;
60};
61
62TAILQ_HEAD(, pkcs11_provider) pkcs11_providers;
63
64struct pkcs11_key {
65	struct pkcs11_provider	*provider;
66	CK_ULONG		slotidx;
67	int			(*orig_finish)(RSA *rsa);
68	RSA_METHOD		rsa_method;
69	char			*keyid;
70	int			keyid_len;
71};
72
73int pkcs11_interactive = 0;
74
75int
76pkcs11_init(int interactive)
77{
78	pkcs11_interactive = interactive;
79	TAILQ_INIT(&pkcs11_providers);
80	return (0);
81}
82
83/*
84 * finalize a provider shared libarary, it's no longer usable.
85 * however, there might still be keys referencing this provider,
86 * so the actuall freeing of memory is handled by pkcs11_provider_unref().
87 * this is called when a provider gets unregistered.
88 */
89static void
90pkcs11_provider_finalize(struct pkcs11_provider *p)
91{
92	CK_RV rv;
93	CK_ULONG i;
94
95	debug("pkcs11_provider_finalize: %p refcount %d valid %d",
96	    p, p->refcount, p->valid);
97	if (!p->valid)
98		return;
99	for (i = 0; i < p->nslots; i++) {
100		if (p->slotinfo[i].session &&
101		    (rv = p->function_list->C_CloseSession(
102		    p->slotinfo[i].session)) != CKR_OK)
103			error("C_CloseSession failed: %lu", rv);
104	}
105	if ((rv = p->function_list->C_Finalize(NULL)) != CKR_OK)
106		error("C_Finalize failed: %lu", rv);
107	p->valid = 0;
108	p->function_list = NULL;
109	dlclose(p->handle);
110}
111
112/*
113 * remove a reference to the provider.
114 * called when a key gets destroyed or when the provider is unregistered.
115 */
116static void
117pkcs11_provider_unref(struct pkcs11_provider *p)
118{
119	debug("pkcs11_provider_unref: %p refcount %d", p, p->refcount);
120	if (--p->refcount <= 0) {
121		if (p->valid)
122			error("pkcs11_provider_unref: %p still valid", p);
123		free(p->slotlist);
124		free(p->slotinfo);
125		free(p);
126	}
127}
128
129/* unregister all providers, keys might still point to the providers */
130void
131pkcs11_terminate(void)
132{
133	struct pkcs11_provider *p;
134
135	while ((p = TAILQ_FIRST(&pkcs11_providers)) != NULL) {
136		TAILQ_REMOVE(&pkcs11_providers, p, next);
137		pkcs11_provider_finalize(p);
138		pkcs11_provider_unref(p);
139	}
140}
141
142/* lookup provider by name */
143static struct pkcs11_provider *
144pkcs11_provider_lookup(char *provider_id)
145{
146	struct pkcs11_provider *p;
147
148	TAILQ_FOREACH(p, &pkcs11_providers, next) {
149		debug("check %p %s", p, p->name);
150		if (!strcmp(provider_id, p->name))
151			return (p);
152	}
153	return (NULL);
154}
155
156/* unregister provider by name */
157int
158pkcs11_del_provider(char *provider_id)
159{
160	struct pkcs11_provider *p;
161
162	if ((p = pkcs11_provider_lookup(provider_id)) != NULL) {
163		TAILQ_REMOVE(&pkcs11_providers, p, next);
164		pkcs11_provider_finalize(p);
165		pkcs11_provider_unref(p);
166		return (0);
167	}
168	return (-1);
169}
170
171/* openssl callback for freeing an RSA key */
172static int
173pkcs11_rsa_finish(RSA *rsa)
174{
175	struct pkcs11_key	*k11;
176	int rv = -1;
177
178	if ((k11 = RSA_get_app_data(rsa)) != NULL) {
179		if (k11->orig_finish)
180			rv = k11->orig_finish(rsa);
181		if (k11->provider)
182			pkcs11_provider_unref(k11->provider);
183		free(k11->keyid);
184		free(k11);
185	}
186	return (rv);
187}
188
189/* find a single 'obj' for given attributes */
190static int
191pkcs11_find(struct pkcs11_provider *p, CK_ULONG slotidx, CK_ATTRIBUTE *attr,
192    CK_ULONG nattr, CK_OBJECT_HANDLE *obj)
193{
194	CK_FUNCTION_LIST	*f;
195	CK_SESSION_HANDLE	session;
196	CK_ULONG		nfound = 0;
197	CK_RV			rv;
198	int			ret = -1;
199
200	f = p->function_list;
201	session = p->slotinfo[slotidx].session;
202	if ((rv = f->C_FindObjectsInit(session, attr, nattr)) != CKR_OK) {
203		error("C_FindObjectsInit failed (nattr %lu): %lu", nattr, rv);
204		return (-1);
205	}
206	if ((rv = f->C_FindObjects(session, obj, 1, &nfound)) != CKR_OK ||
207	    nfound != 1) {
208		debug("C_FindObjects failed (nfound %lu nattr %lu): %lu",
209		    nfound, nattr, rv);
210	} else
211		ret = 0;
212	if ((rv = f->C_FindObjectsFinal(session)) != CKR_OK)
213		error("C_FindObjectsFinal failed: %lu", rv);
214	return (ret);
215}
216
217/* openssl callback doing the actual signing operation */
218static int
219pkcs11_rsa_private_encrypt(int flen, const u_char *from, u_char *to, RSA *rsa,
220    int padding)
221{
222	struct pkcs11_key	*k11;
223	struct pkcs11_slotinfo	*si;
224	CK_FUNCTION_LIST	*f;
225	CK_OBJECT_HANDLE	obj;
226	CK_ULONG		tlen = 0;
227	CK_RV			rv;
228	CK_OBJECT_CLASS		private_key_class = CKO_PRIVATE_KEY;
229	CK_BBOOL		true_val = CK_TRUE;
230	CK_MECHANISM		mech = {
231		CKM_RSA_PKCS, NULL_PTR, 0
232	};
233	CK_ATTRIBUTE		key_filter[] = {
234		{CKA_CLASS, NULL, sizeof(private_key_class) },
235		{CKA_ID, NULL, 0},
236		{CKA_SIGN, NULL, sizeof(true_val) }
237	};
238	char			*pin, prompt[1024];
239	int			rval = -1;
240
241	/* some compilers complain about non-constant initializer so we
242	   use NULL in CK_ATTRIBUTE above and set the values here */
243	key_filter[0].pValue = &private_key_class;
244	key_filter[2].pValue = &true_val;
245
246	if ((k11 = RSA_get_app_data(rsa)) == NULL) {
247		error("RSA_get_app_data failed for rsa %p", rsa);
248		return (-1);
249	}
250	if (!k11->provider || !k11->provider->valid) {
251		error("no pkcs11 (valid) provider for rsa %p", rsa);
252		return (-1);
253	}
254	f = k11->provider->function_list;
255	si = &k11->provider->slotinfo[k11->slotidx];
256	if ((si->token.flags & CKF_LOGIN_REQUIRED) && !si->logged_in) {
257		if (!pkcs11_interactive) {
258			error("need pin");
259			return (-1);
260		}
261		snprintf(prompt, sizeof(prompt), "Enter PIN for '%s': ",
262		    si->token.label);
263		pin = read_passphrase(prompt, RP_ALLOW_EOF);
264		if (pin == NULL)
265			return (-1);	/* bail out */
266		if ((rv = f->C_Login(si->session, CKU_USER,
267		    (u_char *)pin, strlen(pin))) != CKR_OK) {
268			free(pin);
269			error("C_Login failed: %lu", rv);
270			return (-1);
271		}
272		free(pin);
273		si->logged_in = 1;
274	}
275	key_filter[1].pValue = k11->keyid;
276	key_filter[1].ulValueLen = k11->keyid_len;
277	/* try to find object w/CKA_SIGN first, retry w/o */
278	if (pkcs11_find(k11->provider, k11->slotidx, key_filter, 3, &obj) < 0 &&
279	    pkcs11_find(k11->provider, k11->slotidx, key_filter, 2, &obj) < 0) {
280		error("cannot find private key");
281	} else if ((rv = f->C_SignInit(si->session, &mech, obj)) != CKR_OK) {
282		error("C_SignInit failed: %lu", rv);
283	} else {
284		/* XXX handle CKR_BUFFER_TOO_SMALL */
285		tlen = RSA_size(rsa);
286		rv = f->C_Sign(si->session, (CK_BYTE *)from, flen, to, &tlen);
287		if (rv == CKR_OK)
288			rval = tlen;
289		else
290			error("C_Sign failed: %lu", rv);
291	}
292	return (rval);
293}
294
295static int
296pkcs11_rsa_private_decrypt(int flen, const u_char *from, u_char *to, RSA *rsa,
297    int padding)
298{
299	return (-1);
300}
301
302/* redirect private key operations for rsa key to pkcs11 token */
303static int
304pkcs11_rsa_wrap(struct pkcs11_provider *provider, CK_ULONG slotidx,
305    CK_ATTRIBUTE *keyid_attrib, RSA *rsa)
306{
307	struct pkcs11_key	*k11;
308	const RSA_METHOD	*def = RSA_get_default_method();
309
310	k11 = xcalloc(1, sizeof(*k11));
311	k11->provider = provider;
312	provider->refcount++;	/* provider referenced by RSA key */
313	k11->slotidx = slotidx;
314	/* identify key object on smartcard */
315	k11->keyid_len = keyid_attrib->ulValueLen;
316	k11->keyid = xmalloc(k11->keyid_len);
317	memcpy(k11->keyid, keyid_attrib->pValue, k11->keyid_len);
318	k11->orig_finish = def->finish;
319	memcpy(&k11->rsa_method, def, sizeof(k11->rsa_method));
320	k11->rsa_method.name = "pkcs11";
321	k11->rsa_method.rsa_priv_enc = pkcs11_rsa_private_encrypt;
322	k11->rsa_method.rsa_priv_dec = pkcs11_rsa_private_decrypt;
323	k11->rsa_method.finish = pkcs11_rsa_finish;
324	RSA_set_method(rsa, &k11->rsa_method);
325	RSA_set_app_data(rsa, k11);
326	return (0);
327}
328
329/* remove trailing spaces */
330static void
331rmspace(u_char *buf, size_t len)
332{
333	size_t i;
334
335	if (!len)
336		return;
337	for (i = len - 1;  i > 0; i--)
338		if (i == len - 1 || buf[i] == ' ')
339			buf[i] = '\0';
340		else
341			break;
342}
343
344/*
345 * open a pkcs11 session and login if required.
346 * if pin == NULL we delay login until key use
347 */
348static int
349pkcs11_open_session(struct pkcs11_provider *p, CK_ULONG slotidx, char *pin)
350{
351	CK_RV			rv;
352	CK_FUNCTION_LIST	*f;
353	CK_SESSION_HANDLE	session;
354	int			login_required;
355
356	f = p->function_list;
357	login_required = p->slotinfo[slotidx].token.flags & CKF_LOGIN_REQUIRED;
358	if (pin && login_required && !strlen(pin)) {
359		error("pin required");
360		return (-1);
361	}
362	if ((rv = f->C_OpenSession(p->slotlist[slotidx], CKF_RW_SESSION|
363	    CKF_SERIAL_SESSION, NULL, NULL, &session))
364	    != CKR_OK) {
365		error("C_OpenSession failed: %lu", rv);
366		return (-1);
367	}
368	if (login_required && pin) {
369		if ((rv = f->C_Login(session, CKU_USER,
370		    (u_char *)pin, strlen(pin))) != CKR_OK) {
371			error("C_Login failed: %lu", rv);
372			if ((rv = f->C_CloseSession(session)) != CKR_OK)
373				error("C_CloseSession failed: %lu", rv);
374			return (-1);
375		}
376		p->slotinfo[slotidx].logged_in = 1;
377	}
378	p->slotinfo[slotidx].session = session;
379	return (0);
380}
381
382/*
383 * lookup public keys for token in slot identified by slotidx,
384 * add 'wrapped' public keys to the 'keysp' array and increment nkeys.
385 * keysp points to an (possibly empty) array with *nkeys keys.
386 */
387static int
388pkcs11_fetch_keys(struct pkcs11_provider *p, CK_ULONG slotidx, Key ***keysp,
389    int *nkeys)
390{
391	Key			*key;
392	RSA			*rsa;
393	int			i;
394	CK_RV			rv;
395	CK_OBJECT_HANDLE	obj;
396	CK_ULONG		nfound;
397	CK_SESSION_HANDLE	session;
398	CK_FUNCTION_LIST	*f;
399	CK_OBJECT_CLASS		pubkey_class = CKO_PUBLIC_KEY;
400	CK_ATTRIBUTE		pubkey_filter[] = {
401		{ CKA_CLASS, NULL, sizeof(pubkey_class) }
402	};
403	CK_ATTRIBUTE		attribs[] = {
404		{ CKA_ID, NULL, 0 },
405		{ CKA_MODULUS, NULL, 0 },
406		{ CKA_PUBLIC_EXPONENT, NULL, 0 }
407	};
408
409	/* some compilers complain about non-constant initializer so we
410	   use NULL in CK_ATTRIBUTE above and set the value here */
411	pubkey_filter[0].pValue = &pubkey_class;
412
413	f = p->function_list;
414	session = p->slotinfo[slotidx].session;
415	/* setup a filter the looks for public keys */
416	if ((rv = f->C_FindObjectsInit(session, pubkey_filter, 1)) != CKR_OK) {
417		error("C_FindObjectsInit failed: %lu", rv);
418		return (-1);
419	}
420	while (1) {
421		/* XXX 3 attributes in attribs[] */
422		for (i = 0; i < 3; i++) {
423			attribs[i].pValue = NULL;
424			attribs[i].ulValueLen = 0;
425		}
426		if ((rv = f->C_FindObjects(session, &obj, 1, &nfound)) != CKR_OK
427		    || nfound == 0)
428			break;
429		/* found a key, so figure out size of the attributes */
430		if ((rv = f->C_GetAttributeValue(session, obj, attribs, 3))
431		    != CKR_OK) {
432			error("C_GetAttributeValue failed: %lu", rv);
433			continue;
434		}
435		/* check that none of the attributes are zero length */
436		if (attribs[0].ulValueLen == 0 ||
437		    attribs[1].ulValueLen == 0 ||
438		    attribs[2].ulValueLen == 0) {
439			continue;
440		}
441		/* allocate buffers for attributes */
442		for (i = 0; i < 3; i++)
443			attribs[i].pValue = xmalloc(attribs[i].ulValueLen);
444		/* retrieve ID, modulus and public exponent of RSA key */
445		if ((rv = f->C_GetAttributeValue(session, obj, attribs, 3))
446		    != CKR_OK) {
447			error("C_GetAttributeValue failed: %lu", rv);
448		} else if ((rsa = RSA_new()) == NULL) {
449			error("RSA_new failed");
450		} else {
451			rsa->n = BN_bin2bn(attribs[1].pValue,
452			    attribs[1].ulValueLen, NULL);
453			rsa->e = BN_bin2bn(attribs[2].pValue,
454			    attribs[2].ulValueLen, NULL);
455			if (rsa->n && rsa->e &&
456			    pkcs11_rsa_wrap(p, slotidx, &attribs[0], rsa) == 0) {
457				key = key_new(KEY_UNSPEC);
458				key->rsa = rsa;
459				key->type = KEY_RSA;
460				key->flags |= KEY_FLAG_EXT;
461				/* expand key array and add key */
462				*keysp = xrealloc(*keysp, *nkeys + 1,
463				    sizeof(Key *));
464				(*keysp)[*nkeys] = key;
465				*nkeys = *nkeys + 1;
466				debug("have %d keys", *nkeys);
467			} else {
468				RSA_free(rsa);
469			}
470		}
471		for (i = 0; i < 3; i++)
472			free(attribs[i].pValue);
473	}
474	if ((rv = f->C_FindObjectsFinal(session)) != CKR_OK)
475		error("C_FindObjectsFinal failed: %lu", rv);
476	return (0);
477}
478
479/* register a new provider, fails if provider already exists */
480int
481pkcs11_add_provider(char *provider_id, char *pin, Key ***keyp)
482{
483	int nkeys, need_finalize = 0;
484	struct pkcs11_provider *p = NULL;
485	void *handle = NULL;
486	CK_RV (*getfunctionlist)(CK_FUNCTION_LIST **);
487	CK_RV rv;
488	CK_FUNCTION_LIST *f = NULL;
489	CK_TOKEN_INFO *token;
490	CK_ULONG i;
491
492	*keyp = NULL;
493	if (pkcs11_provider_lookup(provider_id) != NULL) {
494		error("provider already registered: %s", provider_id);
495		goto fail;
496	}
497	/* open shared pkcs11-libarary */
498	if ((handle = dlopen(provider_id, RTLD_NOW)) == NULL) {
499		error("dlopen %s failed: %s", provider_id, dlerror());
500		goto fail;
501	}
502	if ((getfunctionlist = dlsym(handle, "C_GetFunctionList")) == NULL) {
503		error("dlsym(C_GetFunctionList) failed: %s", dlerror());
504		goto fail;
505	}
506	p = xcalloc(1, sizeof(*p));
507	p->name = xstrdup(provider_id);
508	p->handle = handle;
509	/* setup the pkcs11 callbacks */
510	if ((rv = (*getfunctionlist)(&f)) != CKR_OK) {
511		error("C_GetFunctionList failed: %lu", rv);
512		goto fail;
513	}
514	p->function_list = f;
515	if ((rv = f->C_Initialize(NULL)) != CKR_OK) {
516		error("C_Initialize failed: %lu", rv);
517		goto fail;
518	}
519	need_finalize = 1;
520	if ((rv = f->C_GetInfo(&p->info)) != CKR_OK) {
521		error("C_GetInfo failed: %lu", rv);
522		goto fail;
523	}
524	rmspace(p->info.manufacturerID, sizeof(p->info.manufacturerID));
525	rmspace(p->info.libraryDescription, sizeof(p->info.libraryDescription));
526	debug("manufacturerID <%s> cryptokiVersion %d.%d"
527	    " libraryDescription <%s> libraryVersion %d.%d",
528	    p->info.manufacturerID,
529	    p->info.cryptokiVersion.major,
530	    p->info.cryptokiVersion.minor,
531	    p->info.libraryDescription,
532	    p->info.libraryVersion.major,
533	    p->info.libraryVersion.minor);
534	if ((rv = f->C_GetSlotList(CK_TRUE, NULL, &p->nslots)) != CKR_OK) {
535		error("C_GetSlotList failed: %lu", rv);
536		goto fail;
537	}
538	if (p->nslots == 0) {
539		error("no slots");
540		goto fail;
541	}
542	p->slotlist = xcalloc(p->nslots, sizeof(CK_SLOT_ID));
543	if ((rv = f->C_GetSlotList(CK_TRUE, p->slotlist, &p->nslots))
544	    != CKR_OK) {
545		error("C_GetSlotList failed: %lu", rv);
546		goto fail;
547	}
548	p->slotinfo = xcalloc(p->nslots, sizeof(struct pkcs11_slotinfo));
549	p->valid = 1;
550	nkeys = 0;
551	for (i = 0; i < p->nslots; i++) {
552		token = &p->slotinfo[i].token;
553		if ((rv = f->C_GetTokenInfo(p->slotlist[i], token))
554		    != CKR_OK) {
555			error("C_GetTokenInfo failed: %lu", rv);
556			continue;
557		}
558		rmspace(token->label, sizeof(token->label));
559		rmspace(token->manufacturerID, sizeof(token->manufacturerID));
560		rmspace(token->model, sizeof(token->model));
561		rmspace(token->serialNumber, sizeof(token->serialNumber));
562		debug("label <%s> manufacturerID <%s> model <%s> serial <%s>"
563		    " flags 0x%lx",
564		    token->label, token->manufacturerID, token->model,
565		    token->serialNumber, token->flags);
566		/* open session, login with pin and retrieve public keys */
567		if (pkcs11_open_session(p, i, pin) == 0)
568			pkcs11_fetch_keys(p, i, keyp, &nkeys);
569	}
570	if (nkeys > 0) {
571		TAILQ_INSERT_TAIL(&pkcs11_providers, p, next);
572		p->refcount++;	/* add to provider list */
573		return (nkeys);
574	}
575	error("no keys");
576	/* don't add the provider, since it does not have any keys */
577fail:
578	if (need_finalize && (rv = f->C_Finalize(NULL)) != CKR_OK)
579		error("C_Finalize failed: %lu", rv);
580	if (p) {
581		free(p->slotlist);
582		free(p->slotinfo);
583		free(p);
584	}
585	if (handle)
586		dlclose(handle);
587	return (-1);
588}
589
590#else
591
592int
593pkcs11_init(int interactive)
594{
595	return (0);
596}
597
598void
599pkcs11_terminate(void)
600{
601	return;
602}
603
604#endif /* ENABLE_PKCS11 */
605