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-rw-r--r--ssh-pkcs11-client.c392
1 files changed, 392 insertions, 0 deletions
diff --git a/ssh-pkcs11-client.c b/ssh-pkcs11-client.c
new file mode 100644
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--- /dev/null
+++ b/ssh-pkcs11-client.c
@@ -0,0 +1,392 @@
+/* $OpenBSD: ssh-pkcs11-client.c,v 1.16 2020/01/25 00:03:36 djm Exp $ */
+/*
+ * Copyright (c) 2010 Markus Friedl. All rights reserved.
+ * Copyright (c) 2014 Pedro Martelletto. 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 <sys/socket.h>
+
+#include <stdarg.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+
+#include <openssl/ecdsa.h>
+#include <openssl/rsa.h>
+
+#include "openbsd-compat/openssl-compat.h"
+
+#include "pathnames.h"
+#include "xmalloc.h"
+#include "sshbuf.h"
+#include "log.h"
+#include "misc.h"
+#include "sshkey.h"
+#include "authfd.h"
+#include "atomicio.h"
+#include "ssh-pkcs11.h"
+#include "ssherr.h"
+
+/* borrows code from sftp-server and ssh-agent */
+
+static int fd = -1;
+static pid_t pid = -1;
+
+static void
+send_msg(struct sshbuf *m)
+{
+ u_char buf[4];
+ size_t mlen = sshbuf_len(m);
+ int r;
+
+ POKE_U32(buf, mlen);
+ if (atomicio(vwrite, fd, buf, 4) != 4 ||
+ atomicio(vwrite, fd, sshbuf_mutable_ptr(m),
+ sshbuf_len(m)) != sshbuf_len(m))
+ error("write to helper failed");
+ if ((r = sshbuf_consume(m, mlen)) != 0)
+ fatal("%s: buffer error: %s", __func__, ssh_err(r));
+}
+
+static int
+recv_msg(struct sshbuf *m)
+{
+ u_int l, len;
+ u_char c, buf[1024];
+ int r;
+
+ if ((len = atomicio(read, fd, buf, 4)) != 4) {
+ error("read from helper failed: %u", len);
+ return (0); /* XXX */
+ }
+ len = PEEK_U32(buf);
+ if (len > 256 * 1024)
+ fatal("response too long: %u", len);
+ /* read len bytes into m */
+ sshbuf_reset(m);
+ while (len > 0) {
+ l = len;
+ if (l > sizeof(buf))
+ l = sizeof(buf);
+ if (atomicio(read, fd, buf, l) != l) {
+ error("response from helper failed.");
+ return (0); /* XXX */
+ }
+ if ((r = sshbuf_put(m, buf, l)) != 0)
+ fatal("%s: buffer error: %s", __func__, ssh_err(r));
+ len -= l;
+ }
+ if ((r = sshbuf_get_u8(m, &c)) != 0)
+ fatal("%s: buffer error: %s", __func__, ssh_err(r));
+ return c;
+}
+
+int
+pkcs11_init(int interactive)
+{
+ return (0);
+}
+
+void
+pkcs11_terminate(void)
+{
+ if (fd >= 0)
+ close(fd);
+}
+
+static int
+rsa_encrypt(int flen, const u_char *from, u_char *to, RSA *rsa, int padding)
+{
+ struct sshkey *key = NULL;
+ struct sshbuf *msg = NULL;
+ u_char *blob = NULL, *signature = NULL;
+ size_t blen, slen = 0;
+ int r, ret = -1;
+
+ if (padding != RSA_PKCS1_PADDING)
+ goto fail;
+ key = sshkey_new(KEY_UNSPEC);
+ if (key == NULL) {
+ error("%s: sshkey_new failed", __func__);
+ goto fail;
+ }
+ key->type = KEY_RSA;
+ RSA_up_ref(rsa);
+ key->rsa = rsa;
+ if ((r = sshkey_to_blob(key, &blob, &blen)) != 0) {
+ error("%s: sshkey_to_blob: %s", __func__, ssh_err(r));
+ goto fail;
+ }
+ if ((msg = sshbuf_new()) == NULL)
+ fatal("%s: sshbuf_new failed", __func__);
+ if ((r = sshbuf_put_u8(msg, SSH2_AGENTC_SIGN_REQUEST)) != 0 ||
+ (r = sshbuf_put_string(msg, blob, blen)) != 0 ||
+ (r = sshbuf_put_string(msg, from, flen)) != 0 ||
+ (r = sshbuf_put_u32(msg, 0)) != 0)
+ fatal("%s: buffer error: %s", __func__, ssh_err(r));
+ send_msg(msg);
+ sshbuf_reset(msg);
+
+ if (recv_msg(msg) == SSH2_AGENT_SIGN_RESPONSE) {
+ if ((r = sshbuf_get_string(msg, &signature, &slen)) != 0)
+ fatal("%s: buffer error: %s", __func__, ssh_err(r));
+ if (slen <= (size_t)RSA_size(rsa)) {
+ memcpy(to, signature, slen);
+ ret = slen;
+ }
+ free(signature);
+ }
+ fail:
+ free(blob);
+ sshkey_free(key);
+ sshbuf_free(msg);
+ return (ret);
+}
+
+#ifdef HAVE_EC_KEY_METHOD_NEW
+static ECDSA_SIG *
+ecdsa_do_sign(const unsigned char *dgst, int dgst_len, const BIGNUM *inv,
+ const BIGNUM *rp, EC_KEY *ec)
+{
+ struct sshkey *key = NULL;
+ struct sshbuf *msg = NULL;
+ ECDSA_SIG *ret = NULL;
+ const u_char *cp;
+ u_char *blob = NULL, *signature = NULL;
+ size_t blen, slen = 0;
+ int r, nid;
+
+ nid = sshkey_ecdsa_key_to_nid(ec);
+ if (nid < 0) {
+ error("%s: couldn't get curve nid", __func__);
+ goto fail;
+ }
+
+ key = sshkey_new(KEY_UNSPEC);
+ if (key == NULL) {
+ error("%s: sshkey_new failed", __func__);
+ goto fail;
+ }
+ key->ecdsa = ec;
+ key->ecdsa_nid = nid;
+ key->type = KEY_ECDSA;
+ EC_KEY_up_ref(ec);
+
+ if ((r = sshkey_to_blob(key, &blob, &blen)) != 0) {
+ error("%s: sshkey_to_blob: %s", __func__, ssh_err(r));
+ goto fail;
+ }
+ if ((msg = sshbuf_new()) == NULL)
+ fatal("%s: sshbuf_new failed", __func__);
+ if ((r = sshbuf_put_u8(msg, SSH2_AGENTC_SIGN_REQUEST)) != 0 ||
+ (r = sshbuf_put_string(msg, blob, blen)) != 0 ||
+ (r = sshbuf_put_string(msg, dgst, dgst_len)) != 0 ||
+ (r = sshbuf_put_u32(msg, 0)) != 0)
+ fatal("%s: buffer error: %s", __func__, ssh_err(r));
+ send_msg(msg);
+ sshbuf_reset(msg);
+
+ if (recv_msg(msg) == SSH2_AGENT_SIGN_RESPONSE) {
+ if ((r = sshbuf_get_string(msg, &signature, &slen)) != 0)
+ fatal("%s: buffer error: %s", __func__, ssh_err(r));
+ cp = signature;
+ ret = d2i_ECDSA_SIG(NULL, &cp, slen);
+ free(signature);
+ }
+
+ fail:
+ free(blob);
+ sshkey_free(key);
+ sshbuf_free(msg);
+ return (ret);
+}
+#endif /* HAVE_EC_KEY_METHOD_NEW */
+
+static RSA_METHOD *helper_rsa;
+#ifdef HAVE_EC_KEY_METHOD_NEW
+static EC_KEY_METHOD *helper_ecdsa;
+#endif /* HAVE_EC_KEY_METHOD_NEW */
+
+/* redirect private key crypto operations to the ssh-pkcs11-helper */
+static void
+wrap_key(struct sshkey *k)
+{
+ if (k->type == KEY_RSA)
+ RSA_set_method(k->rsa, helper_rsa);
+#ifdef HAVE_EC_KEY_METHOD_NEW
+ else if (k->type == KEY_ECDSA)
+ EC_KEY_set_method(k->ecdsa, helper_ecdsa);
+#endif /* HAVE_EC_KEY_METHOD_NEW */
+ else
+ fatal("%s: unknown key type", __func__);
+}
+
+static int
+pkcs11_start_helper_methods(void)
+{
+ if (helper_rsa != NULL)
+ return (0);
+
+#ifdef HAVE_EC_KEY_METHOD_NEW
+ int (*orig_sign)(int, const unsigned char *, int, unsigned char *,
+ unsigned int *, const BIGNUM *, const BIGNUM *, EC_KEY *) = NULL;
+ if (helper_ecdsa != NULL)
+ return (0);
+ helper_ecdsa = EC_KEY_METHOD_new(EC_KEY_OpenSSL());
+ if (helper_ecdsa == NULL)
+ return (-1);
+ EC_KEY_METHOD_get_sign(helper_ecdsa, &orig_sign, NULL, NULL);
+ EC_KEY_METHOD_set_sign(helper_ecdsa, orig_sign, NULL, ecdsa_do_sign);
+#endif /* HAVE_EC_KEY_METHOD_NEW */
+
+ if ((helper_rsa = RSA_meth_dup(RSA_get_default_method())) == NULL)
+ fatal("%s: RSA_meth_dup failed", __func__);
+ if (!RSA_meth_set1_name(helper_rsa, "ssh-pkcs11-helper") ||
+ !RSA_meth_set_priv_enc(helper_rsa, rsa_encrypt))
+ fatal("%s: failed to prepare method", __func__);
+
+ return (0);
+}
+
+static int
+pkcs11_start_helper(void)
+{
+ int pair[2];
+ char *helper, *verbosity = NULL;
+
+ if (log_level_get() >= SYSLOG_LEVEL_DEBUG1)
+ verbosity = "-vvv";
+
+ if (pkcs11_start_helper_methods() == -1) {
+ error("pkcs11_start_helper_methods failed");
+ return (-1);
+ }
+
+ if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1) {
+ error("socketpair: %s", strerror(errno));
+ return (-1);
+ }
+ if ((pid = fork()) == -1) {
+ error("fork: %s", strerror(errno));
+ return (-1);
+ } else if (pid == 0) {
+ if ((dup2(pair[1], STDIN_FILENO) == -1) ||
+ (dup2(pair[1], STDOUT_FILENO) == -1)) {
+ fprintf(stderr, "dup2: %s\n", strerror(errno));
+ _exit(1);
+ }
+ close(pair[0]);
+ close(pair[1]);
+ helper = getenv("SSH_PKCS11_HELPER");
+ if (helper == NULL || strlen(helper) == 0)
+ helper = _PATH_SSH_PKCS11_HELPER;
+ debug("%s: starting %s %s", __func__, helper,
+ verbosity == NULL ? "" : verbosity);
+ execlp(helper, helper, verbosity, (char *)NULL);
+ fprintf(stderr, "exec: %s: %s\n", helper, strerror(errno));
+ _exit(1);
+ }
+ close(pair[1]);
+ fd = pair[0];
+ return (0);
+}
+
+int
+pkcs11_add_provider(char *name, char *pin, struct sshkey ***keysp,
+ char ***labelsp)
+{
+ struct sshkey *k;
+ int r, type;
+ u_char *blob;
+ char *label;
+ size_t blen;
+ u_int nkeys, i;
+ struct sshbuf *msg;
+
+ if (fd < 0 && pkcs11_start_helper() < 0)
+ return (-1);
+
+ if ((msg = sshbuf_new()) == NULL)
+ fatal("%s: sshbuf_new failed", __func__);
+ if ((r = sshbuf_put_u8(msg, SSH_AGENTC_ADD_SMARTCARD_KEY)) != 0 ||
+ (r = sshbuf_put_cstring(msg, name)) != 0 ||
+ (r = sshbuf_put_cstring(msg, pin)) != 0)
+ fatal("%s: buffer error: %s", __func__, ssh_err(r));
+ send_msg(msg);
+ sshbuf_reset(msg);
+
+ type = recv_msg(msg);
+ if (type == SSH2_AGENT_IDENTITIES_ANSWER) {
+ if ((r = sshbuf_get_u32(msg, &nkeys)) != 0)
+ fatal("%s: buffer error: %s", __func__, ssh_err(r));
+ *keysp = xcalloc(nkeys, sizeof(struct sshkey *));
+ if (labelsp)
+ *labelsp = xcalloc(nkeys, sizeof(char *));
+ for (i = 0; i < nkeys; i++) {
+ /* XXX clean up properly instead of fatal() */
+ if ((r = sshbuf_get_string(msg, &blob, &blen)) != 0 ||
+ (r = sshbuf_get_cstring(msg, &label, NULL)) != 0)
+ fatal("%s: buffer error: %s",
+ __func__, ssh_err(r));
+ if ((r = sshkey_from_blob(blob, blen, &k)) != 0)
+ fatal("%s: bad key: %s", __func__, ssh_err(r));
+ wrap_key(k);
+ (*keysp)[i] = k;
+ if (labelsp)
+ (*labelsp)[i] = label;
+ else
+ free(label);
+ free(blob);
+ }
+ } else if (type == SSH2_AGENT_FAILURE) {
+ if ((r = sshbuf_get_u32(msg, &nkeys)) != 0)
+ nkeys = -1;
+ } else {
+ nkeys = -1;
+ }
+ sshbuf_free(msg);
+ return (nkeys);
+}
+
+int
+pkcs11_del_provider(char *name)
+{
+ int r, ret = -1;
+ struct sshbuf *msg;
+
+ if ((msg = sshbuf_new()) == NULL)
+ fatal("%s: sshbuf_new failed", __func__);
+ if ((r = sshbuf_put_u8(msg, SSH_AGENTC_REMOVE_SMARTCARD_KEY)) != 0 ||
+ (r = sshbuf_put_cstring(msg, name)) != 0 ||
+ (r = sshbuf_put_cstring(msg, "")) != 0)
+ fatal("%s: buffer error: %s", __func__, ssh_err(r));
+ send_msg(msg);
+ sshbuf_reset(msg);
+
+ if (recv_msg(msg) == SSH_AGENT_SUCCESS)
+ ret = 0;
+ sshbuf_free(msg);
+ return (ret);
+}
+
+#endif /* ENABLE_PKCS11 */