ssh-pkcs11.c revision 204861
1/* $OpenBSD: ssh-pkcs11.c,v 1.4 2010/02/24 06:12:53 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		xfree(p->slotlist);
124		xfree(p->slotinfo);
125		xfree(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		if (k11->keyid)
184			xfree(k11->keyid);
185		xfree(k11);
186	}
187	return (rv);
188}
189
190/* openssl callback doing the actual signing operation */
191static int
192pkcs11_rsa_private_encrypt(int flen, const u_char *from, u_char *to, RSA *rsa,
193    int padding)
194{
195	struct pkcs11_key	*k11;
196	struct pkcs11_slotinfo	*si;
197	CK_FUNCTION_LIST	*f;
198	CK_OBJECT_HANDLE	obj;
199	CK_ULONG		tlen = 0, nfound = 0;
200	CK_RV			rv;
201	CK_OBJECT_CLASS		private_key_class = CKO_PRIVATE_KEY;
202	CK_BBOOL		true_val = CK_TRUE;
203	CK_MECHANISM		mech = {
204		CKM_RSA_PKCS, NULL_PTR, 0
205	};
206	CK_ATTRIBUTE		key_filter[] = {
207		{CKA_CLASS, NULL, sizeof(private_key_class) },
208		{CKA_ID, NULL, 0},
209		{CKA_SIGN, NULL, sizeof(true_val) }
210	};
211	char			*pin, prompt[1024];
212	int			rval = -1;
213
214	/* some compilers complain about non-constant initializer so we
215	   use NULL in CK_ATTRIBUTE above and set the values here */
216	key_filter[0].pValue = &private_key_class;
217	key_filter[2].pValue = &true_val;
218
219	if ((k11 = RSA_get_app_data(rsa)) == NULL) {
220		error("RSA_get_app_data failed for rsa %p", rsa);
221		return (-1);
222	}
223	if (!k11->provider || !k11->provider->valid) {
224		error("no pkcs11 (valid) provider for rsa %p", rsa);
225		return (-1);
226	}
227	f = k11->provider->function_list;
228	si = &k11->provider->slotinfo[k11->slotidx];
229	if ((si->token.flags & CKF_LOGIN_REQUIRED) && !si->logged_in) {
230		if (!pkcs11_interactive) {
231			error("need pin");
232			return (-1);
233		}
234		snprintf(prompt, sizeof(prompt), "Enter PIN for '%s': ",
235		    si->token.label);
236		pin = read_passphrase(prompt, RP_ALLOW_EOF);
237		if (pin == NULL)
238			return (-1);	/* bail out */
239		if ((rv = f->C_Login(si->session, CKU_USER, pin, strlen(pin)))
240		    != CKR_OK) {
241			xfree(pin);
242			error("C_Login failed: %lu", rv);
243			return (-1);
244		}
245		xfree(pin);
246		si->logged_in = 1;
247	}
248	key_filter[1].pValue = k11->keyid;
249	key_filter[1].ulValueLen = k11->keyid_len;
250	if ((rv = f->C_FindObjectsInit(si->session, key_filter, 3)) != CKR_OK) {
251		error("C_FindObjectsInit failed: %lu", rv);
252		return (-1);
253	}
254	if ((rv = f->C_FindObjects(si->session, &obj, 1, &nfound)) != CKR_OK ||
255	    nfound != 1) {
256		error("C_FindObjects failed (%lu nfound): %lu", nfound, rv);
257	} else if ((rv = f->C_SignInit(si->session, &mech, obj)) != CKR_OK) {
258		error("C_SignInit failed: %lu", rv);
259	} else {
260		/* XXX handle CKR_BUFFER_TOO_SMALL */
261		tlen = RSA_size(rsa);
262		rv = f->C_Sign(si->session, (CK_BYTE *)from, flen, to, &tlen);
263		if (rv == CKR_OK)
264			rval = tlen;
265		else
266			error("C_Sign failed: %lu", rv);
267	}
268	if ((rv = f->C_FindObjectsFinal(si->session)) != CKR_OK)
269		error("C_FindObjectsFinal failed: %lu", rv);
270	return (rval);
271}
272
273static int
274pkcs11_rsa_private_decrypt(int flen, const u_char *from, u_char *to, RSA *rsa,
275    int padding)
276{
277	return (-1);
278}
279
280/* redirect private key operations for rsa key to pkcs11 token */
281static int
282pkcs11_rsa_wrap(struct pkcs11_provider *provider, CK_ULONG slotidx,
283    CK_ATTRIBUTE *keyid_attrib, RSA *rsa)
284{
285	struct pkcs11_key	*k11;
286	const RSA_METHOD	*def = RSA_get_default_method();
287
288	k11 = xcalloc(1, sizeof(*k11));
289	k11->provider = provider;
290	provider->refcount++;	/* provider referenced by RSA key */
291	k11->slotidx = slotidx;
292	/* identify key object on smartcard */
293	k11->keyid_len = keyid_attrib->ulValueLen;
294	k11->keyid = xmalloc(k11->keyid_len);
295	memcpy(k11->keyid, keyid_attrib->pValue, k11->keyid_len);
296	k11->orig_finish = def->finish;
297	memcpy(&k11->rsa_method, def, sizeof(k11->rsa_method));
298	k11->rsa_method.name = "pkcs11";
299	k11->rsa_method.rsa_priv_enc = pkcs11_rsa_private_encrypt;
300	k11->rsa_method.rsa_priv_dec = pkcs11_rsa_private_decrypt;
301	k11->rsa_method.finish = pkcs11_rsa_finish;
302	RSA_set_method(rsa, &k11->rsa_method);
303	RSA_set_app_data(rsa, k11);
304	return (0);
305}
306
307/* remove trailing spaces */
308static void
309rmspace(char *buf, size_t len)
310{
311	size_t i;
312
313	if (!len)
314		return;
315	for (i = len - 1;  i > 0; i--)
316		if (i == len - 1 || buf[i] == ' ')
317			buf[i] = '\0';
318		else
319			break;
320}
321
322/*
323 * open a pkcs11 session and login if required.
324 * if pin == NULL we delay login until key use
325 */
326static int
327pkcs11_open_session(struct pkcs11_provider *p, CK_ULONG slotidx, char *pin)
328{
329	CK_RV			rv;
330	CK_FUNCTION_LIST	*f;
331	CK_SESSION_HANDLE	session;
332	int			login_required;
333
334	f = p->function_list;
335	login_required = p->slotinfo[slotidx].token.flags & CKF_LOGIN_REQUIRED;
336	if (pin && login_required && !strlen(pin)) {
337		error("pin required");
338		return (-1);
339	}
340	if ((rv = f->C_OpenSession(p->slotlist[slotidx], CKF_RW_SESSION|
341	    CKF_SERIAL_SESSION, NULL, NULL, &session))
342	    != CKR_OK) {
343		error("C_OpenSession failed: %lu", rv);
344		return (-1);
345	}
346	if (login_required && pin) {
347		if ((rv = f->C_Login(session, CKU_USER, pin, strlen(pin)))
348		    != CKR_OK) {
349			error("C_Login failed: %lu", rv);
350			if ((rv = f->C_CloseSession(session)) != CKR_OK)
351				error("C_CloseSession failed: %lu", rv);
352			return (-1);
353		}
354		p->slotinfo[slotidx].logged_in = 1;
355	}
356	p->slotinfo[slotidx].session = session;
357	return (0);
358}
359
360/*
361 * lookup public keys for token in slot identified by slotidx,
362 * add 'wrapped' public keys to the 'keysp' array and increment nkeys.
363 * keysp points to an (possibly empty) array with *nkeys keys.
364 */
365static int
366pkcs11_fetch_keys(struct pkcs11_provider *p, CK_ULONG slotidx, Key ***keysp,
367    int *nkeys)
368{
369	Key			*key;
370	RSA			*rsa;
371	int			i;
372	CK_RV			rv;
373	CK_OBJECT_HANDLE	obj;
374	CK_ULONG		nfound;
375	CK_SESSION_HANDLE	session;
376	CK_FUNCTION_LIST	*f;
377	CK_OBJECT_CLASS		pubkey_class = CKO_PUBLIC_KEY;
378	CK_ATTRIBUTE		pubkey_filter[] = {
379		{ CKA_CLASS, NULL, sizeof(pubkey_class) }
380	};
381	CK_ATTRIBUTE		attribs[] = {
382		{ CKA_ID, NULL, 0 },
383		{ CKA_MODULUS, NULL, 0 },
384		{ CKA_PUBLIC_EXPONENT, NULL, 0 }
385	};
386
387	/* some compilers complain about non-constant initializer so we
388	   use NULL in CK_ATTRIBUTE above and set the value here */
389	pubkey_filter[0].pValue = &pubkey_class;
390
391	f = p->function_list;
392	session = p->slotinfo[slotidx].session;
393	/* setup a filter the looks for public keys */
394	if ((rv = f->C_FindObjectsInit(session, pubkey_filter, 1)) != CKR_OK) {
395		error("C_FindObjectsInit failed: %lu", rv);
396		return (-1);
397	}
398	while (1) {
399		/* XXX 3 attributes in attribs[] */
400		for (i = 0; i < 3; i++) {
401			attribs[i].pValue = NULL;
402			attribs[i].ulValueLen = 0;
403		}
404		if ((rv = f->C_FindObjects(session, &obj, 1, &nfound)) != CKR_OK
405		    || nfound == 0)
406			break;
407		/* found a key, so figure out size of the attributes */
408		if ((rv = f->C_GetAttributeValue(session, obj, attribs, 3))
409		    != CKR_OK) {
410			error("C_GetAttributeValue failed: %lu", rv);
411			continue;
412		}
413		/* allocate buffers for attributes, XXX check ulValueLen? */
414		for (i = 0; i < 3; i++)
415			attribs[i].pValue = xmalloc(attribs[i].ulValueLen);
416		/* retrieve ID, modulus and public exponent of RSA key */
417		if ((rv = f->C_GetAttributeValue(session, obj, attribs, 3))
418		    != CKR_OK) {
419			error("C_GetAttributeValue failed: %lu", rv);
420		} else if ((rsa = RSA_new()) == NULL) {
421			error("RSA_new failed");
422		} else {
423			rsa->n = BN_bin2bn(attribs[1].pValue,
424			    attribs[1].ulValueLen, NULL);
425			rsa->e = BN_bin2bn(attribs[2].pValue,
426			    attribs[2].ulValueLen, NULL);
427			if (rsa->n && rsa->e &&
428			    pkcs11_rsa_wrap(p, slotidx, &attribs[0], rsa) == 0) {
429				key = key_new(KEY_UNSPEC);
430				key->rsa = rsa;
431				key->type = KEY_RSA;
432				key->flags |= KEY_FLAG_EXT;
433				/* expand key array and add key */
434				*keysp = xrealloc(*keysp, *nkeys + 1,
435				    sizeof(Key *));
436				(*keysp)[*nkeys] = key;
437				*nkeys = *nkeys + 1;
438				debug("have %d keys", *nkeys);
439			} else {
440				RSA_free(rsa);
441			}
442		}
443		for (i = 0; i < 3; i++)
444			xfree(attribs[i].pValue);
445	}
446	if ((rv = f->C_FindObjectsFinal(session)) != CKR_OK)
447		error("C_FindObjectsFinal failed: %lu", rv);
448	return (0);
449}
450
451/* register a new provider, fails if provider already exists */
452int
453pkcs11_add_provider(char *provider_id, char *pin, Key ***keyp)
454{
455	int nkeys, need_finalize = 0;
456	struct pkcs11_provider *p = NULL;
457	void *handle = NULL;
458	CK_RV (*getfunctionlist)(CK_FUNCTION_LIST **);
459	CK_RV rv;
460	CK_FUNCTION_LIST *f = NULL;
461	CK_TOKEN_INFO *token;
462	CK_ULONG i;
463
464	*keyp = NULL;
465	if (pkcs11_provider_lookup(provider_id) != NULL) {
466		error("provider already registered: %s", provider_id);
467		goto fail;
468	}
469	/* open shared pkcs11-libarary */
470	if ((handle = dlopen(provider_id, RTLD_NOW)) == NULL) {
471		error("dlopen %s failed: %s", provider_id, dlerror());
472		goto fail;
473	}
474	if ((getfunctionlist = dlsym(handle, "C_GetFunctionList")) == NULL) {
475		error("dlsym(C_GetFunctionList) failed: %s", dlerror());
476		goto fail;
477	}
478	p = xcalloc(1, sizeof(*p));
479	p->name = xstrdup(provider_id);
480	p->handle = handle;
481	/* setup the pkcs11 callbacks */
482	if ((rv = (*getfunctionlist)(&f)) != CKR_OK) {
483		error("C_GetFunctionList failed: %lu", rv);
484		goto fail;
485	}
486	p->function_list = f;
487	if ((rv = f->C_Initialize(NULL)) != CKR_OK) {
488		error("C_Initialize failed: %lu", rv);
489		goto fail;
490	}
491	need_finalize = 1;
492	if ((rv = f->C_GetInfo(&p->info)) != CKR_OK) {
493		error("C_GetInfo failed: %lu", rv);
494		goto fail;
495	}
496	rmspace(p->info.manufacturerID, sizeof(p->info.manufacturerID));
497	rmspace(p->info.libraryDescription, sizeof(p->info.libraryDescription));
498	debug("manufacturerID <%s> cryptokiVersion %d.%d"
499	    " libraryDescription <%s> libraryVersion %d.%d",
500	    p->info.manufacturerID,
501	    p->info.cryptokiVersion.major,
502	    p->info.cryptokiVersion.minor,
503	    p->info.libraryDescription,
504	    p->info.libraryVersion.major,
505	    p->info.libraryVersion.minor);
506	if ((rv = f->C_GetSlotList(CK_TRUE, NULL, &p->nslots)) != CKR_OK) {
507		error("C_GetSlotList failed: %lu", rv);
508		goto fail;
509	}
510	if (p->nslots == 0) {
511		error("no slots");
512		goto fail;
513	}
514	p->slotlist = xcalloc(p->nslots, sizeof(CK_SLOT_ID));
515	if ((rv = f->C_GetSlotList(CK_TRUE, p->slotlist, &p->nslots))
516	    != CKR_OK) {
517		error("C_GetSlotList failed: %lu", rv);
518		goto fail;
519	}
520	p->slotinfo = xcalloc(p->nslots, sizeof(struct pkcs11_slotinfo));
521	p->valid = 1;
522	nkeys = 0;
523	for (i = 0; i < p->nslots; i++) {
524		token = &p->slotinfo[i].token;
525		if ((rv = f->C_GetTokenInfo(p->slotlist[i], token))
526		    != CKR_OK) {
527			error("C_GetTokenInfo failed: %lu", rv);
528			continue;
529		}
530		rmspace(token->label, sizeof(token->label));
531		rmspace(token->manufacturerID, sizeof(token->manufacturerID));
532		rmspace(token->model, sizeof(token->model));
533		rmspace(token->serialNumber, sizeof(token->serialNumber));
534		debug("label <%s> manufacturerID <%s> model <%s> serial <%s>"
535		    " flags 0x%lx",
536		    token->label, token->manufacturerID, token->model,
537		    token->serialNumber, token->flags);
538		/* open session, login with pin and retrieve public keys */
539		if (pkcs11_open_session(p, i, pin) == 0)
540			pkcs11_fetch_keys(p, i, keyp, &nkeys);
541	}
542	if (nkeys > 0) {
543		TAILQ_INSERT_TAIL(&pkcs11_providers, p, next);
544		p->refcount++;	/* add to provider list */
545		return (nkeys);
546	}
547	error("no keys");
548	/* don't add the provider, since it does not have any keys */
549fail:
550	if (need_finalize && (rv = f->C_Finalize(NULL)) != CKR_OK)
551		error("C_Finalize failed: %lu", rv);
552	if (p) {
553		if (p->slotlist)
554			xfree(p->slotlist);
555		if (p->slotinfo)
556			xfree(p->slotinfo);
557		xfree(p);
558	}
559	if (handle)
560		dlclose(handle);
561	return (-1);
562}
563
564#endif /* ENABLE_PKCS11 */
565