ssh-pkcs11.c - platform/external/openssh - Gitiles

 /* $OpenBSD: ssh-pkcs11.c,v 1.26 2018/02/07 02:06:51 jsing Exp $ */
 /*
  * Copyright (c) 2010 Markus Friedl.  All rights reserved.
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
  * copyright notice and this permission notice appear in all copies.
  *
  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */

 #include "includes.h"

 #ifdef ENABLE_PKCS11

 #include <sys/types.h>
 #ifdef HAVE_SYS_TIME_H
 # include <sys/time.h>
 #endif
 #include <stdarg.h>
 #include <stdio.h>

 #include <string.h>
 #include <dlfcn.h>

 #include "openbsd-compat/sys-queue.h"

 #include <openssl/x509.h>

 #define CRYPTOKI_COMPAT
 #include "pkcs11.h"

 #include "log.h"
 #include "misc.h"
 #include "sshkey.h"
 #include "ssh-pkcs11.h"
 #include "xmalloc.h"

 struct pkcs11_slotinfo {
 	CK_TOKEN_INFO		token;
 	CK_SESSION_HANDLE	session;
 	int			logged_in;
 };

 struct pkcs11_provider {
 	char			*name;
 	void			*handle;
 	CK_FUNCTION_LIST	*function_list;
 	CK_INFO			info;
 	CK_ULONG		nslots;
 	CK_SLOT_ID		*slotlist;
 	struct pkcs11_slotinfo	*slotinfo;
 	int			valid;
 	int			refcount;
 	TAILQ_ENTRY(pkcs11_provider) next;
 };

 TAILQ_HEAD(, pkcs11_provider) pkcs11_providers;

 struct pkcs11_key {
 	struct pkcs11_provider	*provider;
 	CK_ULONG		slotidx;
 	int			(*orig_finish)(RSA *rsa);
 	RSA_METHOD		*rsa_method;
 	char			*keyid;
 	int			keyid_len;
 };

 int pkcs11_interactive = 0;

 int
 pkcs11_init(int interactive)
 {
 	pkcs11_interactive = interactive;
 	TAILQ_INIT(&pkcs11_providers);
 	return (0);
 }

 /*
  * finalize a provider shared libarary, it's no longer usable.
  * however, there might still be keys referencing this provider,
  * so the actuall freeing of memory is handled by pkcs11_provider_unref().
  * this is called when a provider gets unregistered.
  */
 static void
 pkcs11_provider_finalize(struct pkcs11_provider *p)
 {
 	CK_RV rv;
 	CK_ULONG i;

 	debug("pkcs11_provider_finalize: %p refcount %d valid %d",
 	    p, p->refcount, p->valid);
 	if (!p->valid)
 		return;
 	for (i = 0; i < p->nslots; i++) {
 		if (p->slotinfo[i].session &&
 		    (rv = p->function_list->C_CloseSession(
 		    p->slotinfo[i].session)) != CKR_OK)
 			error("C_CloseSession failed: %lu", rv);
 	}
 	if ((rv = p->function_list->C_Finalize(NULL)) != CKR_OK)
 		error("C_Finalize failed: %lu", rv);
 	p->valid = 0;
 	p->function_list = NULL;
 	dlclose(p->handle);
 }

 /*
  * remove a reference to the provider.
  * called when a key gets destroyed or when the provider is unregistered.
  */
 static void
 pkcs11_provider_unref(struct pkcs11_provider *p)
 {
 	debug("pkcs11_provider_unref: %p refcount %d", p, p->refcount);
 	if (--p->refcount <= 0) {
 		if (p->valid)
 			error("pkcs11_provider_unref: %p still valid", p);
 		free(p->slotlist);
 		free(p->slotinfo);
 		free(p);
 	}
 }

 /* unregister all providers, keys might still point to the providers */
 void
 pkcs11_terminate(void)
 {
 	struct pkcs11_provider *p;

 	while ((p = TAILQ_FIRST(&pkcs11_providers)) != NULL) {
 		TAILQ_REMOVE(&pkcs11_providers, p, next);
 		pkcs11_provider_finalize(p);
 		pkcs11_provider_unref(p);
 	}
 }

 /* lookup provider by name */
 static struct pkcs11_provider *
 pkcs11_provider_lookup(char *provider_id)
 {
 	struct pkcs11_provider *p;

 	TAILQ_FOREACH(p, &pkcs11_providers, next) {
 		debug("check %p %s", p, p->name);
 		if (!strcmp(provider_id, p->name))
 			return (p);
 	}
 	return (NULL);
 }

 /* unregister provider by name */
 int
 pkcs11_del_provider(char *provider_id)
 {
 	struct pkcs11_provider *p;

 	if ((p = pkcs11_provider_lookup(provider_id)) != NULL) {
 		TAILQ_REMOVE(&pkcs11_providers, p, next);
 		pkcs11_provider_finalize(p);
 		pkcs11_provider_unref(p);
 		return (0);
 	}
 	return (-1);
 }

 /* openssl callback for freeing an RSA key */
 static int
 pkcs11_rsa_finish(RSA *rsa)
 {
 	struct pkcs11_key	*k11;
 	int rv = -1;

 	if ((k11 = RSA_get_app_data(rsa)) != NULL) {
 		if (k11->orig_finish)
 			rv = k11->orig_finish(rsa);
 		if (k11->provider)
 			pkcs11_provider_unref(k11->provider);
 		RSA_meth_free(k11->rsa_method);
 		free(k11->keyid);
 		free(k11);
 	}
 	return (rv);
 }

 /* find a single 'obj' for given attributes */
 static int
 pkcs11_find(struct pkcs11_provider *p, CK_ULONG slotidx, CK_ATTRIBUTE *attr,
     CK_ULONG nattr, CK_OBJECT_HANDLE *obj)
 {
 	CK_FUNCTION_LIST	*f;
 	CK_SESSION_HANDLE	session;
 	CK_ULONG		nfound = 0;
 	CK_RV			rv;
 	int			ret = -1;

 	f = p->function_list;
 	session = p->slotinfo[slotidx].session;
 	if ((rv = f->C_FindObjectsInit(session, attr, nattr)) != CKR_OK) {
 		error("C_FindObjectsInit failed (nattr %lu): %lu", nattr, rv);
 		return (-1);
 	}
 	if ((rv = f->C_FindObjects(session, obj, 1, &nfound)) != CKR_OK ||
 	    nfound != 1) {
 		debug("C_FindObjects failed (nfound %lu nattr %lu): %lu",
 		    nfound, nattr, rv);
 	} else
 		ret = 0;
 	if ((rv = f->C_FindObjectsFinal(session)) != CKR_OK)
 		error("C_FindObjectsFinal failed: %lu", rv);
 	return (ret);
 }

 /* openssl callback doing the actual signing operation */
 static int
 pkcs11_rsa_private_encrypt(int flen, const u_char *from, u_char *to, RSA *rsa,
     int padding)
 {
 	struct pkcs11_key	*k11;
 	struct pkcs11_slotinfo	*si;
 	CK_FUNCTION_LIST	*f;
 	CK_OBJECT_HANDLE	obj;
 	CK_ULONG		tlen = 0;
 	CK_RV			rv;
 	CK_OBJECT_CLASS	private_key_class = CKO_PRIVATE_KEY;
 	CK_BBOOL		true_val = CK_TRUE;
 	CK_MECHANISM		mech = {
 		CKM_RSA_PKCS, NULL_PTR, 0
 	};
 	CK_ATTRIBUTE		key_filter[] = {
 		{CKA_CLASS, NULL, sizeof(private_key_class) },
 		{CKA_ID, NULL, 0},
 		{CKA_SIGN, NULL, sizeof(true_val) }
 	};
 	char			*pin = NULL, prompt[1024];
 	int			rval = -1;

 	key_filter[0].pValue = &private_key_class;
 	key_filter[2].pValue = &true_val;

 	if ((k11 = RSA_get_app_data(rsa)) == NULL) {
 		error("RSA_get_app_data failed for rsa %p", rsa);
 		return (-1);
 	}
 	if (!k11->provider || !k11->provider->valid) {
 		error("no pkcs11 (valid) provider for rsa %p", rsa);
 		return (-1);
 	}
 	f = k11->provider->function_list;
 	si = &k11->provider->slotinfo[k11->slotidx];
 	if ((si->token.flags & CKF_LOGIN_REQUIRED) && !si->logged_in) {
 		if (!pkcs11_interactive) {
 			error("need pin entry%s", (si->token.flags &
 			    CKF_PROTECTED_AUTHENTICATION_PATH) ?
 			    " on reader keypad" : "");
 			return (-1);
 		}
 		if (si->token.flags & CKF_PROTECTED_AUTHENTICATION_PATH)
 			verbose("Deferring PIN entry to reader keypad.");
 		else {
 			snprintf(prompt, sizeof(prompt),
 			    "Enter PIN for '%s': ", si->token.label);
 			pin = read_passphrase(prompt, RP_ALLOW_EOF);
 			if (pin == NULL)
 				return (-1);	/* bail out */
 		}
 		rv = f->C_Login(si->session, CKU_USER, (u_char *)pin,
 		    (pin != NULL) ? strlen(pin) : 0);
 		if (pin != NULL) {
 			explicit_bzero(pin, strlen(pin));
 			free(pin);
 		}
 		if (rv != CKR_OK && rv != CKR_USER_ALREADY_LOGGED_IN) {
 			error("C_Login failed: %lu", rv);
 			return (-1);
 		}
 		si->logged_in = 1;
 	}
 	key_filter[1].pValue = k11->keyid;
 	key_filter[1].ulValueLen = k11->keyid_len;
 	/* try to find object w/CKA_SIGN first, retry w/o */
 	if (pkcs11_find(k11->provider, k11->slotidx, key_filter, 3, &obj) < 0 &&
 	    pkcs11_find(k11->provider, k11->slotidx, key_filter, 2, &obj) < 0) {
 		error("cannot find private key");
 	} else if ((rv = f->C_SignInit(si->session, &mech, obj)) != CKR_OK) {
 		error("C_SignInit failed: %lu", rv);
 	} else {
 		/* XXX handle CKR_BUFFER_TOO_SMALL */
 		tlen = RSA_size(rsa);
 		rv = f->C_Sign(si->session, (CK_BYTE *)from, flen, to, &tlen);
 		if (rv == CKR_OK)
 			rval = tlen;
 		else
 			error("C_Sign failed: %lu", rv);
 	}
 	return (rval);
 }

 static int
 pkcs11_rsa_private_decrypt(int flen, const u_char *from, u_char *to, RSA *rsa,
     int padding)
 {
 	return (-1);
 }

 /* redirect private key operations for rsa key to pkcs11 token */
 static int
 pkcs11_rsa_wrap(struct pkcs11_provider *provider, CK_ULONG slotidx,
     CK_ATTRIBUTE *keyid_attrib, RSA *rsa)
 {
 	struct pkcs11_key	*k11;
 	const RSA_METHOD	*def = RSA_get_default_method();

 	k11 = xcalloc(1, sizeof(*k11));
 	k11->provider = provider;
 	provider->refcount++;	/* provider referenced by RSA key */
 	k11->slotidx = slotidx;
 	/* identify key object on smartcard */
 	k11->keyid_len = keyid_attrib->ulValueLen;
 	if (k11->keyid_len > 0) {
 		k11->keyid = xmalloc(k11->keyid_len);
 		memcpy(k11->keyid, keyid_attrib->pValue, k11->keyid_len);
 	}
 	k11->rsa_method = RSA_meth_dup(def);
 	if (k11->rsa_method == NULL)
 		fatal("%s: RSA_meth_dup failed", __func__);
 	k11->orig_finish = RSA_meth_get_finish(def);
 	if (!RSA_meth_set1_name(k11->rsa_method, "pkcs11") ||
 	    !RSA_meth_set_priv_enc(k11->rsa_method,
 	    pkcs11_rsa_private_encrypt) ||
 	    !RSA_meth_set_priv_dec(k11->rsa_method,
 	    pkcs11_rsa_private_decrypt) ||
 	    !RSA_meth_set_finish(k11->rsa_method, pkcs11_rsa_finish))
 		fatal("%s: setup pkcs11 method failed", __func__);
 	RSA_set_method(rsa, k11->rsa_method);
 	RSA_set_app_data(rsa, k11);
 	return (0);
 }

 /* remove trailing spaces */
 static void
 rmspace(u_char *buf, size_t len)
 {
 	size_t i;

 	if (!len)
 		return;
 	for (i = len - 1;  i > 0; i--)
 		if (i == len - 1 || buf[i] == ' ')
 			buf[i] = '\0';
 		else
 			break;
 }

 /*
  * open a pkcs11 session and login if required.
  * if pin == NULL we delay login until key use
  */
 static int
 pkcs11_open_session(struct pkcs11_provider *p, CK_ULONG slotidx, char *pin)
 {
 	CK_RV			rv;
 	CK_FUNCTION_LIST	*f;
 	CK_SESSION_HANDLE	session;
 	int			login_required;

 	f = p->function_list;
 	login_required = p->slotinfo[slotidx].token.flags & CKF_LOGIN_REQUIRED;
 	if (pin && login_required && !strlen(pin)) {
 		error("pin required");
 		return (-1);
 	}
 	if ((rv = f->C_OpenSession(p->slotlist[slotidx], CKF_RW_SESSION|
 	    CKF_SERIAL_SESSION, NULL, NULL, &session))
 	    != CKR_OK) {
 		error("C_OpenSession failed: %lu", rv);
 		return (-1);
 	}
 	if (login_required && pin) {
 		rv = f->C_Login(session, CKU_USER,
 		    (u_char *)pin, strlen(pin));
 		if (rv != CKR_OK && rv != CKR_USER_ALREADY_LOGGED_IN) {
 			error("C_Login failed: %lu", rv);
 			if ((rv = f->C_CloseSession(session)) != CKR_OK)
 				error("C_CloseSession failed: %lu", rv);
 			return (-1);
 		}
 		p->slotinfo[slotidx].logged_in = 1;
 	}
 	p->slotinfo[slotidx].session = session;
 	return (0);
 }

 /*
  * lookup public keys for token in slot identified by slotidx,
  * add 'wrapped' public keys to the 'keysp' array and increment nkeys.
  * keysp points to an (possibly empty) array with *nkeys keys.
  */
 static int pkcs11_fetch_keys_filter(struct pkcs11_provider *, CK_ULONG,
     CK_ATTRIBUTE [], CK_ATTRIBUTE [3], struct sshkey ***, int *)
 	__attribute__((__bounded__(__minbytes__,4, 3 * sizeof(CK_ATTRIBUTE))));

 static int
 pkcs11_fetch_keys(struct pkcs11_provider *p, CK_ULONG slotidx,
     struct sshkey ***keysp, int *nkeys)
 {
 	CK_OBJECT_CLASS	pubkey_class = CKO_PUBLIC_KEY;
 	CK_OBJECT_CLASS	cert_class = CKO_CERTIFICATE;
 	CK_ATTRIBUTE		pubkey_filter[] = {
 		{ CKA_CLASS, NULL, sizeof(pubkey_class) }
 	};
 	CK_ATTRIBUTE		cert_filter[] = {
 		{ CKA_CLASS, NULL, sizeof(cert_class) }
 	};
 	CK_ATTRIBUTE		pubkey_attribs[] = {
 		{ CKA_ID, NULL, 0 },
 		{ CKA_MODULUS, NULL, 0 },
 		{ CKA_PUBLIC_EXPONENT, NULL, 0 }
 	};
 	CK_ATTRIBUTE		cert_attribs[] = {
 		{ CKA_ID, NULL, 0 },
 		{ CKA_SUBJECT, NULL, 0 },
 		{ CKA_VALUE, NULL, 0 }
 	};
 	pubkey_filter[0].pValue = &pubkey_class;
 	cert_filter[0].pValue = &cert_class;

 	if (pkcs11_fetch_keys_filter(p, slotidx, pubkey_filter, pubkey_attribs,
 	    keysp, nkeys) < 0 ||
 	    pkcs11_fetch_keys_filter(p, slotidx, cert_filter, cert_attribs,
 	    keysp, nkeys) < 0)
 		return (-1);
 	return (0);
 }

 static int
 pkcs11_key_included(struct sshkey ***keysp, int *nkeys, struct sshkey *key)
 {
 	int i;

 	for (i = 0; i < *nkeys; i++)
 		if (sshkey_equal(key, (*keysp)[i]))
 			return (1);
 	return (0);
 }

 static int
 have_rsa_key(const RSA *rsa)
 {
 	const BIGNUM *rsa_n, *rsa_e;

 	RSA_get0_key(rsa, &rsa_n, &rsa_e, NULL);
 	return rsa_n != NULL && rsa_e != NULL;
 }

 static int
 pkcs11_fetch_keys_filter(struct pkcs11_provider *p, CK_ULONG slotidx,
     CK_ATTRIBUTE filter[], CK_ATTRIBUTE attribs[3],
     struct sshkey ***keysp, int *nkeys)
 {
 	struct sshkey		*key;
 	RSA			*rsa;
 	X509 			*x509;
 	EVP_PKEY		*evp;
 	int			i;
 	const u_char		*cp;
 	CK_RV			rv;
 	CK_OBJECT_HANDLE	obj;
 	CK_ULONG		nfound;
 	CK_SESSION_HANDLE	session;
 	CK_FUNCTION_LIST	*f;

 	f = p->function_list;
 	session = p->slotinfo[slotidx].session;
 	/* setup a filter the looks for public keys */
 	if ((rv = f->C_FindObjectsInit(session, filter, 1)) != CKR_OK) {
 		error("C_FindObjectsInit failed: %lu", rv);
 		return (-1);
 	}
 	while (1) {
 		/* XXX 3 attributes in attribs[] */
 		for (i = 0; i < 3; i++) {
 			attribs[i].pValue = NULL;
 			attribs[i].ulValueLen = 0;
 		}
 		if ((rv = f->C_FindObjects(session, &obj, 1, &nfound)) != CKR_OK
 		    || nfound == 0)
 			break;
 		/* found a key, so figure out size of the attributes */
 		if ((rv = f->C_GetAttributeValue(session, obj, attribs, 3))
 		    != CKR_OK) {
 			error("C_GetAttributeValue failed: %lu", rv);
 			continue;
 		}
 		/*
 		 * Allow CKA_ID (always first attribute) to be empty, but
 		 * ensure that none of the others are zero length.
 		 * XXX assumes CKA_ID is always first.
 		 */
 		if (attribs[1].ulValueLen == 0 ||
 		    attribs[2].ulValueLen == 0) {
 			continue;
 		}
 		/* allocate buffers for attributes */
 		for (i = 0; i < 3; i++) {
 			if (attribs[i].ulValueLen > 0) {
 				attribs[i].pValue = xmalloc(
 				    attribs[i].ulValueLen);
 			}
 		}

 		/*
 		 * retrieve ID, modulus and public exponent of RSA key,
 		 * or ID, subject and value for certificates.
 		 */
 		rsa = NULL;
 		if ((rv = f->C_GetAttributeValue(session, obj, attribs, 3))
 		    != CKR_OK) {
 			error("C_GetAttributeValue failed: %lu", rv);
 		} else if (attribs[1].type == CKA_MODULUS ) {
 			if ((rsa = RSA_new()) == NULL) {
 				error("RSA_new failed");
 			} else {
 				BIGNUM *rsa_n, *rsa_e;

 				rsa_n = BN_bin2bn(attribs[1].pValue,
 				    attribs[1].ulValueLen, NULL);
 				rsa_e = BN_bin2bn(attribs[2].pValue,
 				    attribs[2].ulValueLen, NULL);
 				if (rsa_n != NULL && rsa_e != NULL) {
 					if (!RSA_set0_key(rsa,
 					    rsa_n, rsa_e, NULL))
 						fatal("%s: set key", __func__);
 					rsa_n = rsa_e = NULL; /* transferred */
 				}
 				BN_free(rsa_n);
 				BN_free(rsa_e);
 			}
 		} else {
 			cp = attribs[2].pValue;
 			if ((x509 = X509_new()) == NULL) {
 				error("X509_new failed");
 			} else if (d2i_X509(&x509, &cp, attribs[2].ulValueLen)
 			    == NULL) {
 				error("d2i_X509 failed");
 			} else if ((evp = X509_get_pubkey(x509)) == NULL ||
 			    EVP_PKEY_base_id(evp) != EVP_PKEY_RSA ||
 			    EVP_PKEY_get0_RSA(evp) == NULL) {
 				debug("X509_get_pubkey failed or no rsa");
 			} else if ((rsa = RSAPublicKey_dup(
 			    EVP_PKEY_get0_RSA(evp))) == NULL) {
 				error("RSAPublicKey_dup");
 			}
 			X509_free(x509);
 		}
 		if (rsa && have_rsa_key(rsa) &&
 		    pkcs11_rsa_wrap(p, slotidx, &attribs[0], rsa) == 0) {
 			if ((key = sshkey_new(KEY_UNSPEC)) == NULL)
 				fatal("sshkey_new failed");
 			key->rsa = rsa;
 			key->type = KEY_RSA;
 			key->flags |= SSHKEY_FLAG_EXT;
 			if (pkcs11_key_included(keysp, nkeys, key)) {
 				sshkey_free(key);
 			} else {
 				/* expand key array and add key */
 				*keysp = xrecallocarray(*keysp, *nkeys,
 				    *nkeys + 1, sizeof(struct sshkey *));
 				(*keysp)[*nkeys] = key;
 				*nkeys = *nkeys + 1;
 				debug("have %d keys", *nkeys);
 			}
 		} else if (rsa) {
 			RSA_free(rsa);
 		}
 		for (i = 0; i < 3; i++)
 			free(attribs[i].pValue);
 	}
 	if ((rv = f->C_FindObjectsFinal(session)) != CKR_OK)
 		error("C_FindObjectsFinal failed: %lu", rv);
 	return (0);
 }

 /* register a new provider, fails if provider already exists */
 int
 pkcs11_add_provider(char *provider_id, char *pin, struct sshkey ***keyp)
 {
 	int nkeys, need_finalize = 0;
 	struct pkcs11_provider *p = NULL;
 	void *handle = NULL;
 	CK_RV (*getfunctionlist)(CK_FUNCTION_LIST **);
 	CK_RV rv;
 	CK_FUNCTION_LIST *f = NULL;
 	CK_TOKEN_INFO *token;
 	CK_ULONG i;

 	*keyp = NULL;
 	if (pkcs11_provider_lookup(provider_id) != NULL) {
 		debug("%s: provider already registered: %s",
 		    __func__, provider_id);
 		goto fail;
 	}
 	/* open shared pkcs11-libarary */
 	if ((handle = dlopen(provider_id, RTLD_NOW)) == NULL) {
 		error("dlopen %s failed: %s", provider_id, dlerror());
 		goto fail;
 	}
 	if ((getfunctionlist = dlsym(handle, "C_GetFunctionList")) == NULL) {
 		error("dlsym(C_GetFunctionList) failed: %s", dlerror());
 		goto fail;
 	}
 	p = xcalloc(1, sizeof(*p));
 	p->name = xstrdup(provider_id);
 	p->handle = handle;
 	/* setup the pkcs11 callbacks */
 	if ((rv = (*getfunctionlist)(&f)) != CKR_OK) {
 		error("C_GetFunctionList for provider %s failed: %lu",
 		    provider_id, rv);
 		goto fail;
 	}
 	p->function_list = f;
 	if ((rv = f->C_Initialize(NULL)) != CKR_OK) {
 		error("C_Initialize for provider %s failed: %lu",
 		    provider_id, rv);
 		goto fail;
 	}
 	need_finalize = 1;
 	if ((rv = f->C_GetInfo(&p->info)) != CKR_OK) {
 		error("C_GetInfo for provider %s failed: %lu",
 		    provider_id, rv);
 		goto fail;
 	}
 	rmspace(p->info.manufacturerID, sizeof(p->info.manufacturerID));
 	rmspace(p->info.libraryDescription, sizeof(p->info.libraryDescription));
 	debug("provider %s: manufacturerID <%s> cryptokiVersion %d.%d"
 	    " libraryDescription <%s> libraryVersion %d.%d",
 	    provider_id,
 	    p->info.manufacturerID,
 	    p->info.cryptokiVersion.major,
 	    p->info.cryptokiVersion.minor,
 	    p->info.libraryDescription,
 	    p->info.libraryVersion.major,
 	    p->info.libraryVersion.minor);
 	if ((rv = f->C_GetSlotList(CK_TRUE, NULL, &p->nslots)) != CKR_OK) {
 		error("C_GetSlotList failed: %lu", rv);
 		goto fail;
 	}
 	if (p->nslots == 0) {
 		debug("%s: provider %s returned no slots", __func__,
 		    provider_id);
 		goto fail;
 	}
 	p->slotlist = xcalloc(p->nslots, sizeof(CK_SLOT_ID));
 	if ((rv = f->C_GetSlotList(CK_TRUE, p->slotlist, &p->nslots))
 	    != CKR_OK) {
 		error("C_GetSlotList for provider %s failed: %lu",
 		    provider_id, rv);
 		goto fail;
 	}
 	p->slotinfo = xcalloc(p->nslots, sizeof(struct pkcs11_slotinfo));
 	p->valid = 1;
 	nkeys = 0;
 	for (i = 0; i < p->nslots; i++) {
 		token = &p->slotinfo[i].token;
 		if ((rv = f->C_GetTokenInfo(p->slotlist[i], token))
 		    != CKR_OK) {
 			error("C_GetTokenInfo for provider %s slot %lu "
 			    "failed: %lu", provider_id, (unsigned long)i, rv);
 			continue;
 		}
 		if ((token->flags & CKF_TOKEN_INITIALIZED) == 0) {
 			debug2("%s: ignoring uninitialised token in "
 			    "provider %s slot %lu", __func__,
 			    provider_id, (unsigned long)i);
 			continue;
 		}
 		rmspace(token->label, sizeof(token->label));
 		rmspace(token->manufacturerID, sizeof(token->manufacturerID));
 		rmspace(token->model, sizeof(token->model));
 		rmspace(token->serialNumber, sizeof(token->serialNumber));
 		debug("provider %s slot %lu: label <%s> manufacturerID <%s> "
 		    "model <%s> serial <%s> flags 0x%lx",
 		    provider_id, (unsigned long)i,
 		    token->label, token->manufacturerID, token->model,
 		    token->serialNumber, token->flags);
 		/* open session, login with pin and retrieve public keys */
 		if (pkcs11_open_session(p, i, pin) == 0)
 			pkcs11_fetch_keys(p, i, keyp, &nkeys);
 	}
 	if (nkeys > 0) {
 		TAILQ_INSERT_TAIL(&pkcs11_providers, p, next);
 		p->refcount++;	/* add to provider list */
 		return (nkeys);
 	}
 	debug("%s: provider %s returned no keys", __func__, provider_id);
 	/* don't add the provider, since it does not have any keys */
 fail:
 	if (need_finalize && (rv = f->C_Finalize(NULL)) != CKR_OK)
 		error("C_Finalize for provider %s failed: %lu",
 		    provider_id, rv);
 	if (p) {
 		free(p->slotlist);
 		free(p->slotinfo);
 		free(p);
 	}
 	if (handle)
 		dlclose(handle);
 	return (-1);
 }

 #else

 int
 pkcs11_init(int interactive)
 {
 	return (0);
 }

 void
 pkcs11_terminate(void)
 {
 	return;
 }

 #endif /* ENABLE_PKCS11 */
	/* $OpenBSD: ssh-pkcs11.c,v 1.26 2018/02/07 02:06:51 jsing Exp $ */
	/*
	* Copyright (c) 2010 Markus Friedl. All rights reserved.
	*
	* Permission to use, copy, modify, and distribute this software for any
	* purpose with or without fee is hereby granted, provided that the above
	* copyright notice and this permission notice appear in all copies.
	*
	* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
	* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
	* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
	* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
	* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
	* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
	* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
	*/

	#include "includes.h"

	#ifdef ENABLE_PKCS11

	#include <sys/types.h>
	#ifdef HAVE_SYS_TIME_H
	# include <sys/time.h>
	#endif
	#include <stdarg.h>
	#include <stdio.h>

	#include <string.h>
	#include <dlfcn.h>

	#include "openbsd-compat/sys-queue.h"

	#include <openssl/x509.h>

	#define CRYPTOKI_COMPAT
	#include "pkcs11.h"

	#include "log.h"
	#include "misc.h"
	#include "sshkey.h"
	#include "ssh-pkcs11.h"
	#include "xmalloc.h"

	struct pkcs11_slotinfo {
	CK_TOKEN_INFO token;
	CK_SESSION_HANDLE session;
	int logged_in;
	};

	struct pkcs11_provider {
	char *name;
	void *handle;
	CK_FUNCTION_LIST *function_list;
	CK_INFO info;
	CK_ULONG nslots;
	CK_SLOT_ID *slotlist;
	struct pkcs11_slotinfo *slotinfo;
	int valid;
	int refcount;
	TAILQ_ENTRY(pkcs11_provider) next;
	};

	TAILQ_HEAD(, pkcs11_provider) pkcs11_providers;

	struct pkcs11_key {
	struct pkcs11_provider *provider;
	CK_ULONG slotidx;
	int (orig_finish)(RSA rsa);
	RSA_METHOD *rsa_method;
	char *keyid;
	int keyid_len;
	};

	int pkcs11_interactive = 0;

	int
	pkcs11_init(int interactive)
	{
	pkcs11_interactive = interactive;
	TAILQ_INIT(&pkcs11_providers);
	return (0);
	}

	/*
	* finalize a provider shared libarary, it's no longer usable.
	* however, there might still be keys referencing this provider,
	* so the actuall freeing of memory is handled by pkcs11_provider_unref().
	* this is called when a provider gets unregistered.
	*/
	static void
	pkcs11_provider_finalize(struct pkcs11_provider *p)
	{
	CK_RV rv;
	CK_ULONG i;

	debug("pkcs11_provider_finalize: %p refcount %d valid %d",
	p, p->refcount, p->valid);
	if (!p->valid)
	return;
	for (i = 0; i < p->nslots; i++) {
	if (p->slotinfo[i].session &&
	(rv = p->function_list->C_CloseSession(
	p->slotinfo[i].session)) != CKR_OK)
	error("C_CloseSession failed: %lu", rv);
	}
	if ((rv = p->function_list->C_Finalize(NULL)) != CKR_OK)
	error("C_Finalize failed: %lu", rv);
	p->valid = 0;
	p->function_list = NULL;
	dlclose(p->handle);
	}

	/*
	* remove a reference to the provider.
	* called when a key gets destroyed or when the provider is unregistered.
	*/
	static void
	pkcs11_provider_unref(struct pkcs11_provider *p)
	{
	debug("pkcs11_provider_unref: %p refcount %d", p, p->refcount);
	if (--p->refcount <= 0) {
	if (p->valid)
	error("pkcs11_provider_unref: %p still valid", p);
	free(p->slotlist);
	free(p->slotinfo);
	free(p);
	}
	}

	/* unregister all providers, keys might still point to the providers */
	void
	pkcs11_terminate(void)
	{
	struct pkcs11_provider *p;

	while ((p = TAILQ_FIRST(&pkcs11_providers)) != NULL) {
	TAILQ_REMOVE(&pkcs11_providers, p, next);
	pkcs11_provider_finalize(p);
	pkcs11_provider_unref(p);
	}
	}

	/* lookup provider by name */
	static struct pkcs11_provider *
	pkcs11_provider_lookup(char *provider_id)
	{
	struct pkcs11_provider *p;

	TAILQ_FOREACH(p, &pkcs11_providers, next) {
	debug("check %p %s", p, p->name);
	if (!strcmp(provider_id, p->name))
	return (p);
	}
	return (NULL);
	}

	/* unregister provider by name */
	int
	pkcs11_del_provider(char *provider_id)
	{
	struct pkcs11_provider *p;

	if ((p = pkcs11_provider_lookup(provider_id)) != NULL) {
	TAILQ_REMOVE(&pkcs11_providers, p, next);
	pkcs11_provider_finalize(p);
	pkcs11_provider_unref(p);
	return (0);
	}
	return (-1);
	}

	/* openssl callback for freeing an RSA key */
	static int
	pkcs11_rsa_finish(RSA *rsa)
	{
	struct pkcs11_key *k11;
	int rv = -1;

	if ((k11 = RSA_get_app_data(rsa)) != NULL) {
	if (k11->orig_finish)
	rv = k11->orig_finish(rsa);
	if (k11->provider)
	pkcs11_provider_unref(k11->provider);
	RSA_meth_free(k11->rsa_method);
	free(k11->keyid);
	free(k11);
	}
	return (rv);
	}

	/* find a single 'obj' for given attributes */
	static int
	pkcs11_find(struct pkcs11_provider p, CK_ULONG slotidx, CK_ATTRIBUTE attr,
	CK_ULONG nattr, CK_OBJECT_HANDLE *obj)
	{
	CK_FUNCTION_LIST *f;
	CK_SESSION_HANDLE session;
	CK_ULONG nfound = 0;
	CK_RV rv;
	int ret = -1;

	f = p->function_list;
	session = p->slotinfo[slotidx].session;
	if ((rv = f->C_FindObjectsInit(session, attr, nattr)) != CKR_OK) {
	error("C_FindObjectsInit failed (nattr %lu): %lu", nattr, rv);
	return (-1);
	}
	if ((rv = f->C_FindObjects(session, obj, 1, &nfound)) != CKR_OK \|\|
	nfound != 1) {
	debug("C_FindObjects failed (nfound %lu nattr %lu): %lu",
	nfound, nattr, rv);
	} else
	ret = 0;
	if ((rv = f->C_FindObjectsFinal(session)) != CKR_OK)
	error("C_FindObjectsFinal failed: %lu", rv);
	return (ret);
	}

	/* openssl callback doing the actual signing operation */
	static int
	pkcs11_rsa_private_encrypt(int flen, const u_char from, u_char to, RSA *rsa,
	int padding)
	{
	struct pkcs11_key *k11;
	struct pkcs11_slotinfo *si;
	CK_FUNCTION_LIST *f;
	CK_OBJECT_HANDLE obj;
	CK_ULONG tlen = 0;
	CK_RV rv;
	CK_OBJECT_CLASS private_key_class = CKO_PRIVATE_KEY;
	CK_BBOOL true_val = CK_TRUE;
	CK_MECHANISM mech = {
	CKM_RSA_PKCS, NULL_PTR, 0
	};
	CK_ATTRIBUTE key_filter[] = {
	{CKA_CLASS, NULL, sizeof(private_key_class) },
	{CKA_ID, NULL, 0},
	{CKA_SIGN, NULL, sizeof(true_val) }
	};
	char *pin = NULL, prompt[1024];
	int rval = -1;

	key_filter[0].pValue = &private_key_class;
	key_filter[2].pValue = &true_val;

	if ((k11 = RSA_get_app_data(rsa)) == NULL) {
	error("RSA_get_app_data failed for rsa %p", rsa);
	return (-1);
	}
	if (!k11->provider \|\| !k11->provider->valid) {
	error("no pkcs11 (valid) provider for rsa %p", rsa);
	return (-1);
	}
	f = k11->provider->function_list;
	si = &k11->provider->slotinfo[k11->slotidx];
	if ((si->token.flags & CKF_LOGIN_REQUIRED) && !si->logged_in) {
	if (!pkcs11_interactive) {
	error("need pin entry%s", (si->token.flags &
	CKF_PROTECTED_AUTHENTICATION_PATH) ?
	" on reader keypad" : "");
	return (-1);
	}
	if (si->token.flags & CKF_PROTECTED_AUTHENTICATION_PATH)
	verbose("Deferring PIN entry to reader keypad.");
	else {
	snprintf(prompt, sizeof(prompt),
	"Enter PIN for '%s': ", si->token.label);
	pin = read_passphrase(prompt, RP_ALLOW_EOF);
	if (pin == NULL)
	return (-1); /* bail out */
	}
	rv = f->C_Login(si->session, CKU_USER, (u_char *)pin,
	(pin != NULL) ? strlen(pin) : 0);
	if (pin != NULL) {
	explicit_bzero(pin, strlen(pin));
	free(pin);
	}
	if (rv != CKR_OK && rv != CKR_USER_ALREADY_LOGGED_IN) {
	error("C_Login failed: %lu", rv);
	return (-1);
	}
	si->logged_in = 1;
	}
	key_filter[1].pValue = k11->keyid;
	key_filter[1].ulValueLen = k11->keyid_len;
	/* try to find object w/CKA_SIGN first, retry w/o */
	if (pkcs11_find(k11->provider, k11->slotidx, key_filter, 3, &obj) < 0 &&
	pkcs11_find(k11->provider, k11->slotidx, key_filter, 2, &obj) < 0) {
	error("cannot find private key");
	} else if ((rv = f->C_SignInit(si->session, &mech, obj)) != CKR_OK) {
	error("C_SignInit failed: %lu", rv);
	} else {
	/* XXX handle CKR_BUFFER_TOO_SMALL */
	tlen = RSA_size(rsa);
	rv = f->C_Sign(si->session, (CK_BYTE *)from, flen, to, &tlen);
	if (rv == CKR_OK)
	rval = tlen;
	else
	error("C_Sign failed: %lu", rv);
	}
	return (rval);
	}

	static int
	pkcs11_rsa_private_decrypt(int flen, const u_char from, u_char to, RSA *rsa,
	int padding)
	{
	return (-1);
	}

	/* redirect private key operations for rsa key to pkcs11 token */
	static int
	pkcs11_rsa_wrap(struct pkcs11_provider *provider, CK_ULONG slotidx,
	CK_ATTRIBUTE keyid_attrib, RSA rsa)
	{
	struct pkcs11_key *k11;
	const RSA_METHOD *def = RSA_get_default_method();

	k11 = xcalloc(1, sizeof(*k11));
	k11->provider = provider;
	provider->refcount++; /* provider referenced by RSA key */
	k11->slotidx = slotidx;
	/* identify key object on smartcard */
	k11->keyid_len = keyid_attrib->ulValueLen;
	if (k11->keyid_len > 0) {
	k11->keyid = xmalloc(k11->keyid_len);
	memcpy(k11->keyid, keyid_attrib->pValue, k11->keyid_len);
	}
	k11->rsa_method = RSA_meth_dup(def);
	if (k11->rsa_method == NULL)
	fatal("%s: RSA_meth_dup failed", __func__);
	k11->orig_finish = RSA_meth_get_finish(def);
	if (!RSA_meth_set1_name(k11->rsa_method, "pkcs11") \|\|
	!RSA_meth_set_priv_enc(k11->rsa_method,
	pkcs11_rsa_private_encrypt) \|\|
	!RSA_meth_set_priv_dec(k11->rsa_method,
	pkcs11_rsa_private_decrypt) \|\|
	!RSA_meth_set_finish(k11->rsa_method, pkcs11_rsa_finish))
	fatal("%s: setup pkcs11 method failed", __func__);
	RSA_set_method(rsa, k11->rsa_method);
	RSA_set_app_data(rsa, k11);
	return (0);
	}

	/* remove trailing spaces */
	static void
	rmspace(u_char *buf, size_t len)
	{
	size_t i;

	if (!len)
	return;
	for (i = len - 1; i > 0; i--)
	if (i == len - 1 \|\| buf[i] == ' ')
	buf[i] = '\0';
	else
	break;
	}

	/*
	* open a pkcs11 session and login if required.
	* if pin == NULL we delay login until key use
	*/
	static int
	pkcs11_open_session(struct pkcs11_provider p, CK_ULONG slotidx, char pin)
	{
	CK_RV rv;
	CK_FUNCTION_LIST *f;
	CK_SESSION_HANDLE session;
	int login_required;

	f = p->function_list;
	login_required = p->slotinfo[slotidx].token.flags & CKF_LOGIN_REQUIRED;
	if (pin && login_required && !strlen(pin)) {
	error("pin required");
	return (-1);
	}
	if ((rv = f->C_OpenSession(p->slotlist[slotidx], CKF_RW_SESSION\|
	CKF_SERIAL_SESSION, NULL, NULL, &session))
	!= CKR_OK) {
	error("C_OpenSession failed: %lu", rv);
	return (-1);
	}
	if (login_required && pin) {
	rv = f->C_Login(session, CKU_USER,
	(u_char *)pin, strlen(pin));
	if (rv != CKR_OK && rv != CKR_USER_ALREADY_LOGGED_IN) {
	error("C_Login failed: %lu", rv);
	if ((rv = f->C_CloseSession(session)) != CKR_OK)
	error("C_CloseSession failed: %lu", rv);
	return (-1);
	}
	p->slotinfo[slotidx].logged_in = 1;
	}
	p->slotinfo[slotidx].session = session;
	return (0);
	}

	/*
	* lookup public keys for token in slot identified by slotidx,
	* add 'wrapped' public keys to the 'keysp' array and increment nkeys.
	* keysp points to an (possibly empty) array with *nkeys keys.
	*/
	static int pkcs11_fetch_keys_filter(struct pkcs11_provider *, CK_ULONG,
	CK_ATTRIBUTE [], CK_ATTRIBUTE [3], struct sshkey **, int )
	__attribute__((__bounded__(__minbytes__,4, 3 * sizeof(CK_ATTRIBUTE))));

	static int
	pkcs11_fetch_keys(struct pkcs11_provider *p, CK_ULONG slotidx,
	struct sshkey **keysp, int nkeys)
	{
	CK_OBJECT_CLASS pubkey_class = CKO_PUBLIC_KEY;
	CK_OBJECT_CLASS cert_class = CKO_CERTIFICATE;
	CK_ATTRIBUTE pubkey_filter[] = {
	{ CKA_CLASS, NULL, sizeof(pubkey_class) }
	};
	CK_ATTRIBUTE cert_filter[] = {
	{ CKA_CLASS, NULL, sizeof(cert_class) }
	};
	CK_ATTRIBUTE pubkey_attribs[] = {
	{ CKA_ID, NULL, 0 },
	{ CKA_MODULUS, NULL, 0 },
	{ CKA_PUBLIC_EXPONENT, NULL, 0 }
	};
	CK_ATTRIBUTE cert_attribs[] = {
	{ CKA_ID, NULL, 0 },
	{ CKA_SUBJECT, NULL, 0 },
	{ CKA_VALUE, NULL, 0 }
	};
	pubkey_filter[0].pValue = &pubkey_class;
	cert_filter[0].pValue = &cert_class;

	if (pkcs11_fetch_keys_filter(p, slotidx, pubkey_filter, pubkey_attribs,
	keysp, nkeys) < 0 \|\|
	pkcs11_fetch_keys_filter(p, slotidx, cert_filter, cert_attribs,
	keysp, nkeys) < 0)
	return (-1);
	return (0);
	}

	static int
	pkcs11_key_included(struct sshkey **keysp, int nkeys, struct sshkey *key)
	{
	int i;

	for (i = 0; i < *nkeys; i++)
	if (sshkey_equal(key, (*keysp)[i]))
	return (1);
	return (0);
	}

	static int
	have_rsa_key(const RSA *rsa)
	{
	const BIGNUM rsa_n, rsa_e;

	RSA_get0_key(rsa, &rsa_n, &rsa_e, NULL);
	return rsa_n != NULL && rsa_e != NULL;
	}

	static int
	pkcs11_fetch_keys_filter(struct pkcs11_provider *p, CK_ULONG slotidx,
	CK_ATTRIBUTE filter[], CK_ATTRIBUTE attribs[3],
	struct sshkey **keysp, int nkeys)
	{
	struct sshkey *key;
	RSA *rsa;
	X509 *x509;
	EVP_PKEY *evp;
	int i;
	const u_char *cp;
	CK_RV rv;
	CK_OBJECT_HANDLE obj;
	CK_ULONG nfound;
	CK_SESSION_HANDLE session;
	CK_FUNCTION_LIST *f;

	f = p->function_list;
	session = p->slotinfo[slotidx].session;
	/* setup a filter the looks for public keys */
	if ((rv = f->C_FindObjectsInit(session, filter, 1)) != CKR_OK) {
	error("C_FindObjectsInit failed: %lu", rv);
	return (-1);
	}
	while (1) {
	/* XXX 3 attributes in attribs[] */
	for (i = 0; i < 3; i++) {
	attribs[i].pValue = NULL;
	attribs[i].ulValueLen = 0;
	}
	if ((rv = f->C_FindObjects(session, &obj, 1, &nfound)) != CKR_OK
	\|\| nfound == 0)
	break;
	/* found a key, so figure out size of the attributes */
	if ((rv = f->C_GetAttributeValue(session, obj, attribs, 3))
	!= CKR_OK) {
	error("C_GetAttributeValue failed: %lu", rv);
	continue;
	}
	/*
	* Allow CKA_ID (always first attribute) to be empty, but
	* ensure that none of the others are zero length.
	* XXX assumes CKA_ID is always first.
	*/
	if (attribs[1].ulValueLen == 0 \|\|
	attribs[2].ulValueLen == 0) {
	continue;
	}
	/* allocate buffers for attributes */
	for (i = 0; i < 3; i++) {
	if (attribs[i].ulValueLen > 0) {
	attribs[i].pValue = xmalloc(
	attribs[i].ulValueLen);
	}
	}

	/*
	* retrieve ID, modulus and public exponent of RSA key,
	* or ID, subject and value for certificates.
	*/
	rsa = NULL;
	if ((rv = f->C_GetAttributeValue(session, obj, attribs, 3))
	!= CKR_OK) {
	error("C_GetAttributeValue failed: %lu", rv);
	} else if (attribs[1].type == CKA_MODULUS ) {
	if ((rsa = RSA_new()) == NULL) {
	error("RSA_new failed");
	} else {
	BIGNUM rsa_n, rsa_e;

	rsa_n = BN_bin2bn(attribs[1].pValue,
	attribs[1].ulValueLen, NULL);
	rsa_e = BN_bin2bn(attribs[2].pValue,
	attribs[2].ulValueLen, NULL);
	if (rsa_n != NULL && rsa_e != NULL) {
	if (!RSA_set0_key(rsa,
	rsa_n, rsa_e, NULL))
	fatal("%s: set key", __func__);
	rsa_n = rsa_e = NULL; /* transferred */
	}
	BN_free(rsa_n);
	BN_free(rsa_e);
	}
	} else {
	cp = attribs[2].pValue;
	if ((x509 = X509_new()) == NULL) {
	error("X509_new failed");
	} else if (d2i_X509(&x509, &cp, attribs[2].ulValueLen)
	== NULL) {
	error("d2i_X509 failed");
	} else if ((evp = X509_get_pubkey(x509)) == NULL \|\|
	EVP_PKEY_base_id(evp) != EVP_PKEY_RSA \|\|
	EVP_PKEY_get0_RSA(evp) == NULL) {
	debug("X509_get_pubkey failed or no rsa");
	} else if ((rsa = RSAPublicKey_dup(
	EVP_PKEY_get0_RSA(evp))) == NULL) {
	error("RSAPublicKey_dup");
	}
	X509_free(x509);
	}
	if (rsa && have_rsa_key(rsa) &&
	pkcs11_rsa_wrap(p, slotidx, &attribs[0], rsa) == 0) {
	if ((key = sshkey_new(KEY_UNSPEC)) == NULL)
	fatal("sshkey_new failed");
	key->rsa = rsa;
	key->type = KEY_RSA;
	key->flags \|= SSHKEY_FLAG_EXT;
	if (pkcs11_key_included(keysp, nkeys, key)) {
	sshkey_free(key);
	} else {
	/* expand key array and add key */
	keysp = xrecallocarray(keysp, *nkeys,
	nkeys + 1, sizeof(struct sshkey ));
	(keysp)[nkeys] = key;
	nkeys = nkeys + 1;
	debug("have %d keys", *nkeys);
	}
	} else if (rsa) {
	RSA_free(rsa);
	}
	for (i = 0; i < 3; i++)
	free(attribs[i].pValue);
	}
	if ((rv = f->C_FindObjectsFinal(session)) != CKR_OK)
	error("C_FindObjectsFinal failed: %lu", rv);
	return (0);
	}

	/* register a new provider, fails if provider already exists */
	int
	pkcs11_add_provider(char provider_id, char pin, struct sshkey ***keyp)
	{
	int nkeys, need_finalize = 0;
	struct pkcs11_provider *p = NULL;
	void *handle = NULL;
	CK_RV (getfunctionlist)(CK_FUNCTION_LIST *);
	CK_RV rv;
	CK_FUNCTION_LIST *f = NULL;
	CK_TOKEN_INFO *token;
	CK_ULONG i;

	*keyp = NULL;
	if (pkcs11_provider_lookup(provider_id) != NULL) {
	debug("%s: provider already registered: %s",
	__func__, provider_id);
	goto fail;
	}
	/* open shared pkcs11-libarary */
	if ((handle = dlopen(provider_id, RTLD_NOW)) == NULL) {
	error("dlopen %s failed: %s", provider_id, dlerror());
	goto fail;
	}
	if ((getfunctionlist = dlsym(handle, "C_GetFunctionList")) == NULL) {
	error("dlsym(C_GetFunctionList) failed: %s", dlerror());
	goto fail;
	}
	p = xcalloc(1, sizeof(*p));
	p->name = xstrdup(provider_id);
	p->handle = handle;
	/* setup the pkcs11 callbacks */
	if ((rv = (*getfunctionlist)(&f)) != CKR_OK) {
	error("C_GetFunctionList for provider %s failed: %lu",
	provider_id, rv);
	goto fail;
	}
	p->function_list = f;
	if ((rv = f->C_Initialize(NULL)) != CKR_OK) {
	error("C_Initialize for provider %s failed: %lu",
	provider_id, rv);
	goto fail;
	}
	need_finalize = 1;
	if ((rv = f->C_GetInfo(&p->info)) != CKR_OK) {
	error("C_GetInfo for provider %s failed: %lu",
	provider_id, rv);
	goto fail;
	}
	rmspace(p->info.manufacturerID, sizeof(p->info.manufacturerID));
	rmspace(p->info.libraryDescription, sizeof(p->info.libraryDescription));
	debug("provider %s: manufacturerID <%s> cryptokiVersion %d.%d"
	" libraryDescription <%s> libraryVersion %d.%d",
	provider_id,
	p->info.manufacturerID,
	p->info.cryptokiVersion.major,
	p->info.cryptokiVersion.minor,
	p->info.libraryDescription,
	p->info.libraryVersion.major,
	p->info.libraryVersion.minor);
	if ((rv = f->C_GetSlotList(CK_TRUE, NULL, &p->nslots)) != CKR_OK) {
	error("C_GetSlotList failed: %lu", rv);
	goto fail;
	}
	if (p->nslots == 0) {
	debug("%s: provider %s returned no slots", __func__,
	provider_id);
	goto fail;
	}
	p->slotlist = xcalloc(p->nslots, sizeof(CK_SLOT_ID));
	if ((rv = f->C_GetSlotList(CK_TRUE, p->slotlist, &p->nslots))
	!= CKR_OK) {
	error("C_GetSlotList for provider %s failed: %lu",
	provider_id, rv);
	goto fail;
	}
	p->slotinfo = xcalloc(p->nslots, sizeof(struct pkcs11_slotinfo));
	p->valid = 1;
	nkeys = 0;
	for (i = 0; i < p->nslots; i++) {
	token = &p->slotinfo[i].token;
	if ((rv = f->C_GetTokenInfo(p->slotlist[i], token))
	!= CKR_OK) {
	error("C_GetTokenInfo for provider %s slot %lu "
	"failed: %lu", provider_id, (unsigned long)i, rv);
	continue;
	}
	if ((token->flags & CKF_TOKEN_INITIALIZED) == 0) {
	debug2("%s: ignoring uninitialised token in "
	"provider %s slot %lu", __func__,
	provider_id, (unsigned long)i);
	continue;
	}
	rmspace(token->label, sizeof(token->label));
	rmspace(token->manufacturerID, sizeof(token->manufacturerID));
	rmspace(token->model, sizeof(token->model));
	rmspace(token->serialNumber, sizeof(token->serialNumber));
	debug("provider %s slot %lu: label <%s> manufacturerID <%s> "
	"model <%s> serial <%s> flags 0x%lx",
	provider_id, (unsigned long)i,
	token->label, token->manufacturerID, token->model,
	token->serialNumber, token->flags);
	/* open session, login with pin and retrieve public keys */
	if (pkcs11_open_session(p, i, pin) == 0)
	pkcs11_fetch_keys(p, i, keyp, &nkeys);
	}
	if (nkeys > 0) {
	TAILQ_INSERT_TAIL(&pkcs11_providers, p, next);
	p->refcount++; /* add to provider list */
	return (nkeys);
	}
	debug("%s: provider %s returned no keys", __func__, provider_id);
	/* don't add the provider, since it does not have any keys */
	fail:
	if (need_finalize && (rv = f->C_Finalize(NULL)) != CKR_OK)
	error("C_Finalize for provider %s failed: %lu",
	provider_id, rv);
	if (p) {
	free(p->slotlist);
	free(p->slotinfo);
	free(p);
	}
	if (handle)
	dlclose(handle);
	return (-1);
	}

	#else

	int
	pkcs11_init(int interactive)
	{
	return (0);
	}

	void
	pkcs11_terminate(void)
	{
	return;
	}

	#endif /* ENABLE_PKCS11 */