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openssh/ssh-pkcs11.c

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/* $OpenBSD: ssh-pkcs11.c,v 1.21 2015/07/18 08:02:17 djm 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);
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;
k11->keyid = xmalloc(k11->keyid_len);
memcpy(k11->keyid, keyid_attrib->pValue, k11->keyid_len);
k11->orig_finish = def->finish;
memcpy(&k11->rsa_method, def, sizeof(k11->rsa_method));
k11->rsa_method.name = "pkcs11";
k11->rsa_method.rsa_priv_enc = pkcs11_rsa_private_encrypt;
k11->rsa_method.rsa_priv_dec = pkcs11_rsa_private_decrypt;
k11->rsa_method.finish = pkcs11_rsa_finish;
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
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 {
rsa->n = BN_bin2bn(attribs[1].pValue,
attribs[1].ulValueLen, NULL);
rsa->e = BN_bin2bn(attribs[2].pValue,
attribs[2].ulValueLen, NULL);
}
} 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->type != EVP_PKEY_RSA ||
evp->pkey.rsa == NULL) {
debug("X509_get_pubkey failed or no rsa");
} else if ((rsa = RSAPublicKey_dup(evp->pkey.rsa))
== NULL) {
error("RSAPublicKey_dup");
}
if (x509)
X509_free(x509);
}
if (rsa && rsa->n && rsa->e &&
pkcs11_rsa_wrap(p, slotidx, &attribs[0], rsa) == 0) {
key = sshkey_new(KEY_UNSPEC);
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 = xreallocarray(*keysp, *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) {
error("provider already registered: %s", 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 failed: %lu", rv);
goto fail;
}
p->function_list = f;
if ((rv = f->C_Initialize(NULL)) != CKR_OK) {
error("C_Initialize failed: %lu", rv);
goto fail;
}
need_finalize = 1;
if ((rv = f->C_GetInfo(&p->info)) != CKR_OK) {
error("C_GetInfo failed: %lu", rv);
goto fail;
}
rmspace(p->info.manufacturerID, sizeof(p->info.manufacturerID));
rmspace(p->info.libraryDescription, sizeof(p->info.libraryDescription));
debug("manufacturerID <%s> cryptokiVersion %d.%d"
" libraryDescription <%s> libraryVersion %d.%d",
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) {
error("no slots");
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 failed: %lu", 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 failed: %lu", rv);
continue;
}
if ((token->flags & CKF_TOKEN_INITIALIZED) == 0) {
debug2("%s: ignoring uninitialised token in slot %lu",
__func__, (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("label <%s> manufacturerID <%s> model <%s> serial <%s>"
" flags 0x%lx",
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);
}
error("no keys");
/* 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 failed: %lu", 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 */
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