1/*	$NetBSD: ssh-pkcs11.c,v 1.4 2011/07/25 03:03:11 christos Exp $	*/
2/* $OpenBSD: ssh-pkcs11.c,v 1.6 2010/06/08 21:32:19 markus Exp $ */
3/*
4 * Copyright (c) 2010 Markus Friedl.  All rights reserved.
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */
18#include "includes.h"
19__RCSID("$NetBSD: ssh-pkcs11.c,v 1.4 2011/07/25 03:03:11 christos Exp $");
20
21#include <sys/types.h>
22#include <sys/queue.h>
23#include <sys/time.h>
24#include <stdarg.h>
25#include <stdio.h>
26
27#include <string.h>
28#include <dlfcn.h>
29
30#define CRYPTOKI_COMPAT
31#include "pkcs11.h"
32
33#include "log.h"
34#include "misc.h"
35#include "key.h"
36#include "ssh-pkcs11.h"
37#include "xmalloc.h"
38
39struct pkcs11_slotinfo {
40	CK_TOKEN_INFO		token;
41	CK_SESSION_HANDLE	session;
42	int			logged_in;
43};
44
45struct pkcs11_provider {
46	char			*name;
47	void			*handle;
48	CK_FUNCTION_LIST	*function_list;
49	CK_INFO			info;
50	CK_ULONG		nslots;
51	CK_SLOT_ID		*slotlist;
52	struct pkcs11_slotinfo	*slotinfo;
53	int			valid;
54	int			refcount;
55	TAILQ_ENTRY(pkcs11_provider) next;
56};
57
58TAILQ_HEAD(, pkcs11_provider) pkcs11_providers;
59
60struct pkcs11_key {
61	struct pkcs11_provider	*provider;
62	CK_ULONG		slotidx;
63	int			(*orig_finish)(RSA *rsa);
64	RSA_METHOD		rsa_method;
65	char			*keyid;
66	int			keyid_len;
67};
68
69int pkcs11_interactive = 0;
70
71int
72pkcs11_init(int interactive)
73{
74	pkcs11_interactive = interactive;
75	TAILQ_INIT(&pkcs11_providers);
76	return (0);
77}
78
79/*
80 * finalize a provider shared libarary, it's no longer usable.
81 * however, there might still be keys referencing this provider,
82 * so the actuall freeing of memory is handled by pkcs11_provider_unref().
83 * this is called when a provider gets unregistered.
84 */
85static void
86pkcs11_provider_finalize(struct pkcs11_provider *p)
87{
88	CK_RV rv;
89	CK_ULONG i;
90
91	debug("pkcs11_provider_finalize: %p refcount %d valid %d",
92	    p, p->refcount, p->valid);
93	if (!p->valid)
94		return;
95	for (i = 0; i < p->nslots; i++) {
96		if (p->slotinfo[i].session &&
97		    (rv = p->function_list->C_CloseSession(
98		    p->slotinfo[i].session)) != CKR_OK)
99			error("C_CloseSession failed: %lu", rv);
100	}
101	if ((rv = p->function_list->C_Finalize(NULL)) != CKR_OK)
102		error("C_Finalize failed: %lu", rv);
103	p->valid = 0;
104	p->function_list = NULL;
105#ifdef HAVE_DLOPEN
106	dlclose(p->handle);
107#endif
108}
109
110/*
111 * remove a reference to the provider.
112 * called when a key gets destroyed or when the provider is unregistered.
113 */
114static void
115pkcs11_provider_unref(struct pkcs11_provider *p)
116{
117	debug("pkcs11_provider_unref: %p refcount %d", p, p->refcount);
118	if (--p->refcount <= 0) {
119		if (p->valid)
120			error("pkcs11_provider_unref: %p still valid", p);
121		xfree(p->slotlist);
122		xfree(p->slotinfo);
123		xfree(p);
124	}
125}
126
127/* unregister all providers, keys might still point to the providers */
128void
129pkcs11_terminate(void)
130{
131	struct pkcs11_provider *p;
132
133	while ((p = TAILQ_FIRST(&pkcs11_providers)) != NULL) {
134		TAILQ_REMOVE(&pkcs11_providers, p, next);
135		pkcs11_provider_finalize(p);
136		pkcs11_provider_unref(p);
137	}
138}
139
140/* lookup provider by name */
141static struct pkcs11_provider *
142pkcs11_provider_lookup(char *provider_id)
143{
144	struct pkcs11_provider *p;
145
146	TAILQ_FOREACH(p, &pkcs11_providers, next) {
147		debug("check %p %s", p, p->name);
148		if (!strcmp(provider_id, p->name))
149			return (p);
150	}
151	return (NULL);
152}
153
154/* unregister provider by name */
155int
156pkcs11_del_provider(char *provider_id)
157{
158	struct pkcs11_provider *p;
159
160	if ((p = pkcs11_provider_lookup(provider_id)) != NULL) {
161		TAILQ_REMOVE(&pkcs11_providers, p, next);
162		pkcs11_provider_finalize(p);
163		pkcs11_provider_unref(p);
164		return (0);
165	}
166	return (-1);
167}
168
169#ifdef HAVE_DLOPEN
170/* openssl callback for freeing an RSA key */
171static int
172pkcs11_rsa_finish(RSA *rsa)
173{
174	struct pkcs11_key	*k11;
175	int rv = -1;
176
177	if ((k11 = RSA_get_app_data(rsa)) != NULL) {
178		if (k11->orig_finish)
179			rv = k11->orig_finish(rsa);
180		if (k11->provider)
181			pkcs11_provider_unref(k11->provider);
182		if (k11->keyid)
183			xfree(k11->keyid);
184		xfree(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 = CK_TRUE;
230	CK_MECHANISM		mech = {
231		CKM_RSA_PKCS, NULL_PTR, 0
232	};
233	CK_ATTRIBUTE		key_filter[] = {
234		{CKA_CLASS, &private_key_class, sizeof(private_key_class) },
235		{CKA_ID, NULL, 0},
236		{CKA_SIGN, &true, sizeof(true) }
237	};
238	char			*pin, prompt[1024];
239	int			rval = -1;
240
241	if ((k11 = RSA_get_app_data(rsa)) == NULL) {
242		error("RSA_get_app_data failed for rsa %p", rsa);
243		return (-1);
244	}
245	if (!k11->provider || !k11->provider->valid) {
246		error("no pkcs11 (valid) provider for rsa %p", rsa);
247		return (-1);
248	}
249	f = k11->provider->function_list;
250	si = &k11->provider->slotinfo[k11->slotidx];
251	if ((si->token.flags & CKF_LOGIN_REQUIRED) && !si->logged_in) {
252		if (!pkcs11_interactive) {
253			error("need pin");
254			return (-1);
255		}
256		snprintf(prompt, sizeof(prompt), "Enter PIN for '%s': ",
257		    si->token.label);
258		pin = read_passphrase(prompt, RP_ALLOW_EOF);
259		if (pin == NULL)
260			return (-1);	/* bail out */
261		if ((rv = f->C_Login(si->session, CKU_USER, pin, strlen(pin)))
262		    != CKR_OK) {
263			xfree(pin);
264			error("C_Login failed: %lu", rv);
265			return (-1);
266		}
267		xfree(pin);
268		si->logged_in = 1;
269	}
270	key_filter[1].pValue = k11->keyid;
271	key_filter[1].ulValueLen = k11->keyid_len;
272	/* try to find object w/CKA_SIGN first, retry w/o */
273	if (pkcs11_find(k11->provider, k11->slotidx, key_filter, 3, &obj) < 0 &&
274	    pkcs11_find(k11->provider, k11->slotidx, key_filter, 2, &obj) < 0) {
275		error("cannot find private key");
276	} else if ((rv = f->C_SignInit(si->session, &mech, obj)) != CKR_OK) {
277		error("C_SignInit failed: %lu", rv);
278	} else {
279		/* XXX handle CKR_BUFFER_TOO_SMALL */
280		tlen = RSA_size(rsa);
281		rv = f->C_Sign(si->session, __UNCONST(from), flen, to, &tlen);
282		if (rv == CKR_OK)
283			rval = tlen;
284		else
285			error("C_Sign failed: %lu", rv);
286	}
287	return (rval);
288}
289
290static int
291pkcs11_rsa_private_decrypt(int flen, const u_char *from, u_char *to, RSA *rsa,
292    int padding)
293{
294	return (-1);
295}
296
297/* redirect private key operations for rsa key to pkcs11 token */
298static int
299pkcs11_rsa_wrap(struct pkcs11_provider *provider, CK_ULONG slotidx,
300    CK_ATTRIBUTE *keyid_attrib, RSA *rsa)
301{
302	struct pkcs11_key	*k11;
303	const RSA_METHOD	*def = RSA_get_default_method();
304
305	k11 = xcalloc(1, sizeof(*k11));
306	k11->provider = provider;
307	provider->refcount++;	/* provider referenced by RSA key */
308	k11->slotidx = slotidx;
309	/* identify key object on smartcard */
310	k11->keyid_len = keyid_attrib->ulValueLen;
311	k11->keyid = xmalloc(k11->keyid_len);
312	memcpy(k11->keyid, keyid_attrib->pValue, k11->keyid_len);
313	k11->orig_finish = def->finish;
314	memcpy(&k11->rsa_method, def, sizeof(k11->rsa_method));
315	k11->rsa_method.name = "pkcs11";
316	k11->rsa_method.rsa_priv_enc = pkcs11_rsa_private_encrypt;
317	k11->rsa_method.rsa_priv_dec = pkcs11_rsa_private_decrypt;
318	k11->rsa_method.finish = pkcs11_rsa_finish;
319	RSA_set_method(rsa, &k11->rsa_method);
320	RSA_set_app_data(rsa, k11);
321	return (0);
322}
323
324/* remove trailing spaces */
325static void
326rmspace(char *buf, size_t len)
327{
328	size_t i;
329
330	if (!len)
331		return;
332	for (i = len - 1;  i > 0; i--)
333		if (i == len - 1 || buf[i] == ' ')
334			buf[i] = '\0';
335		else
336			break;
337}
338
339/*
340 * open a pkcs11 session and login if required.
341 * if pin == NULL we delay login until key use
342 */
343static int
344pkcs11_open_session(struct pkcs11_provider *p, CK_ULONG slotidx, char *pin)
345{
346	CK_RV			rv;
347	CK_FUNCTION_LIST	*f;
348	CK_SESSION_HANDLE	session;
349	int			login_required;
350
351	f = p->function_list;
352	login_required = p->slotinfo[slotidx].token.flags & CKF_LOGIN_REQUIRED;
353	if (pin && login_required && !strlen(pin)) {
354		error("pin required");
355		return (-1);
356	}
357	if ((rv = f->C_OpenSession(p->slotlist[slotidx], CKF_RW_SESSION|
358	    CKF_SERIAL_SESSION, NULL, NULL, &session))
359	    != CKR_OK) {
360		error("C_OpenSession failed: %lu", rv);
361		return (-1);
362	}
363	if (login_required && pin) {
364		if ((rv = f->C_Login(session, CKU_USER, pin, strlen(pin)))
365		    != CKR_OK) {
366			error("C_Login failed: %lu", rv);
367			if ((rv = f->C_CloseSession(session)) != CKR_OK)
368				error("C_CloseSession failed: %lu", rv);
369			return (-1);
370		}
371		p->slotinfo[slotidx].logged_in = 1;
372	}
373	p->slotinfo[slotidx].session = session;
374	return (0);
375}
376
377/*
378 * lookup public keys for token in slot identified by slotidx,
379 * add 'wrapped' public keys to the 'keysp' array and increment nkeys.
380 * keysp points to an (possibly empty) array with *nkeys keys.
381 */
382static int
383pkcs11_fetch_keys(struct pkcs11_provider *p, CK_ULONG slotidx, Key ***keysp,
384    int *nkeys)
385{
386	Key			*key;
387	RSA			*rsa;
388	int			i;
389	CK_RV			rv;
390	CK_OBJECT_HANDLE	obj;
391	CK_ULONG		nfound;
392	CK_SESSION_HANDLE	session;
393	CK_FUNCTION_LIST	*f;
394	CK_OBJECT_CLASS		pubkey_class = CKO_PUBLIC_KEY;
395	CK_ATTRIBUTE		pubkey_filter[] = {
396		{ CKA_CLASS, &pubkey_class, sizeof(pubkey_class) }
397	};
398	CK_ATTRIBUTE		attribs[] = {
399		{ CKA_ID, NULL, 0 },
400		{ CKA_MODULUS, NULL, 0 },
401		{ CKA_PUBLIC_EXPONENT, NULL, 0 }
402	};
403
404	f = p->function_list;
405	session = p->slotinfo[slotidx].session;
406	/* setup a filter the looks for public keys */
407	if ((rv = f->C_FindObjectsInit(session, pubkey_filter, 1)) != CKR_OK) {
408		error("C_FindObjectsInit failed: %lu", rv);
409		return (-1);
410	}
411	while (1) {
412		/* XXX 3 attributes in attribs[] */
413		for (i = 0; i < 3; i++) {
414			attribs[i].pValue = NULL;
415			attribs[i].ulValueLen = 0;
416		}
417		if ((rv = f->C_FindObjects(session, &obj, 1, &nfound)) != CKR_OK
418		    || nfound == 0)
419			break;
420		/* found a key, so figure out size of the attributes */
421		if ((rv = f->C_GetAttributeValue(session, obj, attribs, 3))
422		    != CKR_OK) {
423			error("C_GetAttributeValue failed: %lu", rv);
424			continue;
425		}
426		/* check that none of the attributes are zero length */
427		if (attribs[0].ulValueLen == 0 ||
428		    attribs[1].ulValueLen == 0 ||
429		    attribs[2].ulValueLen == 0) {
430			continue;
431		}
432		/* allocate buffers for attributes */
433		for (i = 0; i < 3; i++)
434			attribs[i].pValue = xmalloc(attribs[i].ulValueLen);
435		/* retrieve ID, modulus and public exponent of RSA key */
436		if ((rv = f->C_GetAttributeValue(session, obj, attribs, 3))
437		    != CKR_OK) {
438			error("C_GetAttributeValue failed: %lu", rv);
439		} else if ((rsa = RSA_new()) == NULL) {
440			error("RSA_new failed");
441		} else {
442			rsa->n = BN_bin2bn(attribs[1].pValue,
443			    attribs[1].ulValueLen, NULL);
444			rsa->e = BN_bin2bn(attribs[2].pValue,
445			    attribs[2].ulValueLen, NULL);
446			if (rsa->n && rsa->e &&
447			    pkcs11_rsa_wrap(p, slotidx, &attribs[0], rsa) == 0) {
448				key = key_new(KEY_UNSPEC);
449				key->rsa = rsa;
450				key->type = KEY_RSA;
451				key->flags |= KEY_FLAG_EXT;
452				/* expand key array and add key */
453				*keysp = xrealloc(*keysp, *nkeys + 1,
454				    sizeof(Key *));
455				(*keysp)[*nkeys] = key;
456				*nkeys = *nkeys + 1;
457				debug("have %d keys", *nkeys);
458			} else {
459				RSA_free(rsa);
460			}
461		}
462		for (i = 0; i < 3; i++)
463			xfree(attribs[i].pValue);
464	}
465	if ((rv = f->C_FindObjectsFinal(session)) != CKR_OK)
466		error("C_FindObjectsFinal failed: %lu", rv);
467	return (0);
468}
469
470/* register a new provider, fails if provider already exists */
471int
472pkcs11_add_provider(char *provider_id, char *pin, Key ***keyp)
473{
474	int nkeys, need_finalize = 0;
475	struct pkcs11_provider *p = NULL;
476	void *handle = NULL;
477	CK_RV (*getfunctionlist)(CK_FUNCTION_LIST **);
478	CK_RV rv;
479	CK_FUNCTION_LIST *f = NULL;
480	CK_TOKEN_INFO *token;
481	CK_ULONG i;
482
483	*keyp = NULL;
484	if (pkcs11_provider_lookup(provider_id) != NULL) {
485		error("provider already registered: %s", provider_id);
486		goto fail;
487	}
488	/* open shared pkcs11-libarary */
489	if ((handle = dlopen(provider_id, RTLD_NOW)) == NULL) {
490		error("dlopen %s failed: %s", provider_id, dlerror());
491		goto fail;
492	}
493	if ((getfunctionlist = dlsym(handle, "C_GetFunctionList")) == NULL) {
494		error("dlsym(C_GetFunctionList) failed: %s", dlerror());
495		goto fail;
496	}
497	p = xcalloc(1, sizeof(*p));
498	p->name = xstrdup(provider_id);
499	p->handle = handle;
500	/* setup the pkcs11 callbacks */
501	if ((rv = (*getfunctionlist)(&f)) != CKR_OK) {
502		error("C_GetFunctionList failed: %lu", rv);
503		goto fail;
504	}
505	p->function_list = f;
506	if ((rv = f->C_Initialize(NULL)) != CKR_OK) {
507		error("C_Initialize failed: %lu", rv);
508		goto fail;
509	}
510	need_finalize = 1;
511	if ((rv = f->C_GetInfo(&p->info)) != CKR_OK) {
512		error("C_GetInfo failed: %lu", rv);
513		goto fail;
514	}
515	rmspace(p->info.manufacturerID, sizeof(p->info.manufacturerID));
516	rmspace(p->info.libraryDescription, sizeof(p->info.libraryDescription));
517	debug("manufacturerID <%s> cryptokiVersion %d.%d"
518	    " libraryDescription <%s> libraryVersion %d.%d",
519	    p->info.manufacturerID,
520	    p->info.cryptokiVersion.major,
521	    p->info.cryptokiVersion.minor,
522	    p->info.libraryDescription,
523	    p->info.libraryVersion.major,
524	    p->info.libraryVersion.minor);
525	if ((rv = f->C_GetSlotList(CK_TRUE, NULL, &p->nslots)) != CKR_OK) {
526		error("C_GetSlotList failed: %lu", rv);
527		goto fail;
528	}
529	if (p->nslots == 0) {
530		error("no slots");
531		goto fail;
532	}
533	p->slotlist = xcalloc(p->nslots, sizeof(CK_SLOT_ID));
534	if ((rv = f->C_GetSlotList(CK_TRUE, p->slotlist, &p->nslots))
535	    != CKR_OK) {
536		error("C_GetSlotList failed: %lu", rv);
537		goto fail;
538	}
539	p->slotinfo = xcalloc(p->nslots, sizeof(struct pkcs11_slotinfo));
540	p->valid = 1;
541	nkeys = 0;
542	for (i = 0; i < p->nslots; i++) {
543		token = &p->slotinfo[i].token;
544		if ((rv = f->C_GetTokenInfo(p->slotlist[i], token))
545		    != CKR_OK) {
546			error("C_GetTokenInfo failed: %lu", rv);
547			continue;
548		}
549		rmspace(token->label, sizeof(token->label));
550		rmspace(token->manufacturerID, sizeof(token->manufacturerID));
551		rmspace(token->model, sizeof(token->model));
552		rmspace(token->serialNumber, sizeof(token->serialNumber));
553		debug("label <%s> manufacturerID <%s> model <%s> serial <%s>"
554		    " flags 0x%lx",
555		    token->label, token->manufacturerID, token->model,
556		    token->serialNumber, token->flags);
557		/* open session, login with pin and retrieve public keys */
558		if (pkcs11_open_session(p, i, pin) == 0)
559			pkcs11_fetch_keys(p, i, keyp, &nkeys);
560	}
561	if (nkeys > 0) {
562		TAILQ_INSERT_TAIL(&pkcs11_providers, p, next);
563		p->refcount++;	/* add to provider list */
564		return (nkeys);
565	}
566	error("no keys");
567	/* don't add the provider, since it does not have any keys */
568fail:
569	if (need_finalize && (rv = f->C_Finalize(NULL)) != CKR_OK)
570		error("C_Finalize failed: %lu", rv);
571	if (p) {
572		if (p->slotlist)
573			xfree(p->slotlist);
574		if (p->slotinfo)
575			xfree(p->slotinfo);
576		xfree(p);
577	}
578	if (handle)
579		dlclose(handle);
580	return (-1);
581}
582#else
583int
584pkcs11_add_provider(char *provider_id, char *pin, Key ***keyp)
585{
586	error("dlopen() not supported");
587	return (-1);
588}
589#endif
590