- markus@cvs.openbsd.org 2010/02/08 10:50:20

     [pathnames.h readconf.c readconf.h scp.1 sftp.1 ssh-add.1 ssh-add.c]
     [ssh-agent.c ssh-keygen.1 ssh-keygen.c ssh.1 ssh.c ssh_config.5]
     replace our obsolete smartcard code with PKCS#11.
        ftp://ftp.rsasecurity.com/pub/pkcs/pkcs-11/v2-20/pkcs-11v2-20.pdf
     ssh(1) and ssh-keygen(1) use dlopen(3) directly to talk to a PKCS#11
     provider (shared library) while ssh-agent(1) delegates PKCS#11 to
     a forked a ssh-pkcs11-helper process.
     PKCS#11 is currently a compile time option.
     feedback and ok djm@; inspired by patches from Alon Bar-Lev
`

1 files changed, 544 insertions, 0 deletions

diff --git a/ssh-pkcs11.c b/ssh-pkcs11.c
new file mode 100644
index 000000000..f82454329
--- /dev/null
+++ b/ssh-pkcs11.c
@@ -0,0 +1,544 @@
+/*
+ * 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 <sys/types.h>
+#include <sys/queue.h>
+#include <stdarg.h>
+#include <stdio.h>
+
+#include <string.h>
+#include <dlfcn.h>
+
+#define CRYPTOKI_COMPAT
+#include "pkcs11.h"
+
+#include "log.h"
+#include "misc.h"
+#include "key.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);
+                xfree(p->slotlist);
+                xfree(p->slotinfo);
+                xfree(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);
+                if (k11->keyid)
+                        xfree(k11->keyid);
+                xfree(k11);
+        }
+        return (rv);
+}
+
+/* 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, nfound = 0;
+        CK_RV                   rv;
+        CK_OBJECT_CLASS         private_key_class = CKO_PRIVATE_KEY;
+        CK_BBOOL                true = CK_TRUE;
+        CK_MECHANISM            mech = {
+                CKM_RSA_PKCS, NULL_PTR, 0
+        };
+        CK_ATTRIBUTE            key_filter[] = {
+                {CKA_CLASS, &private_key_class, sizeof(private_key_class) },
+                {CKA_ID, NULL, 0},
+                {CKA_SIGN, &true, sizeof(true) }
+        };
+        char                    *pin, prompt[1024];
+        int                     rval = -1;
+
+        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");
+                        return (-1);
+                }
+                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 */
+                if ((rv = f->C_Login(si->session, CKU_USER, pin, strlen(pin)))
+                    != CKR_OK) {
+                        xfree(pin);
+                        error("C_Login failed: %lu", rv);
+                        return (-1);
+                }
+                xfree(pin);
+                si->logged_in = 1;
+        }
+        key_filter[1].pValue = k11->keyid;
+        key_filter[1].ulValueLen = k11->keyid_len;
+        if ((rv = f->C_FindObjectsInit(si->session, key_filter, 3)) != CKR_OK) {
+                error("C_FindObjectsInit failed: %lu", rv);
+                return (-1);
+        }
+        if ((rv = f->C_FindObjects(si->session, &obj, 1, &nfound)) != CKR_OK ||
+            nfound != 1) {
+                error("C_FindObjects failed (%lu nfound): %lu", nfound, rv);
+        } 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);
+        }
+        if ((rv = f->C_FindObjectsFinal(si->session)) != CKR_OK)
+                error("C_FindObjectsFinal 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(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) {
+                if ((rv = f->C_Login(session, CKU_USER, pin, strlen(pin)))
+                    != CKR_OK) {
+                        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(struct pkcs11_provider *p, CK_ULONG slotidx, Key ***keysp,
+    int *nkeys)
+{
+        Key                     *key;
+        RSA                     *rsa;
+        int                     i;
+        CK_RV                   rv;
+        CK_OBJECT_HANDLE        obj;
+        CK_ULONG                nfound;
+        CK_SESSION_HANDLE       session;
+        CK_FUNCTION_LIST        *f;
+        CK_OBJECT_CLASS         pubkey_class = CKO_PUBLIC_KEY;
+        CK_ATTRIBUTE            pubkey_filter[] = {
+                { CKA_CLASS, &pubkey_class, sizeof(pubkey_class) }
+        };
+        CK_ATTRIBUTE            attribs[] = {
+                { CKA_ID, NULL, 0 },
+                { CKA_MODULUS, NULL, 0 },
+                { CKA_PUBLIC_EXPONENT, NULL, 0 }
+        };
+
+        f = p->function_list;
+        session = p->slotinfo[slotidx].session;
+        /* setup a filter the looks for public keys */
+        if ((rv = f->C_FindObjectsInit(session, pubkey_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;
+                }
+                /* allocate buffers for attributes, XXX check ulValueLen? */
+                for (i = 0; i < 3; i++)
+                        attribs[i].pValue = xmalloc(attribs[i].ulValueLen);
+                /* retrieve ID, modulus and public exponent of RSA key */
+                if ((rv = f->C_GetAttributeValue(session, obj, attribs, 3))
+                    != CKR_OK) {
+                        error("C_GetAttributeValue failed: %lu", rv);
+                } else 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);
+                        if (rsa->n && rsa->e &&
+                            pkcs11_rsa_wrap(p, slotidx, &attribs[0], rsa) == 0) {
+                                key = key_new(KEY_UNSPEC);
+                                key->rsa = rsa;
+                                key->type = KEY_RSA;
+                                key->flags |= KEY_FLAG_EXT;
+                                /* expand key array and add key */
+                                *keysp = xrealloc(*keysp, *nkeys + 1,
+                                    sizeof(Key *));
+                                (*keysp)[*nkeys] = key;
+                                *nkeys = *nkeys + 1;
+                                debug("have %d keys", *nkeys);
+                        } else {
+                                RSA_free(rsa);
+                        }
+                }
+                for (i = 0; i < 3; i++)
+                        xfree(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, Key ***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;
+                }
+                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) {
+                if (p->slotlist)
+                        xfree(p->slotlist);
+                if (p->slotinfo)
+                        xfree(p->slotinfo);
+                xfree(p);
+        }
+        if (handle)
+                dlclose(handle);
+        return (-1);
+}