ssh-pkcs11-client.c - third_party/openssh-portable - Git at Google

 /* $OpenBSD: ssh-pkcs11-client.c,v 1.19 2023/12/18 14:46:56 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 <limits.h>

 #include <openssl/ecdsa.h>
 #include <openssl/rsa.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"

 #include "openbsd-compat/openssl-compat.h"

 #if !defined(OPENSSL_HAS_ECC) || !defined(HAVE_EC_KEY_METHOD_NEW)
 #define EC_KEY_METHOD void
 #define EC_KEY void
 #endif

 /* borrows code from sftp-server and ssh-agent */

 /*
  * Maintain a list of ssh-pkcs11-helper subprocesses. These may be looked up
  * by provider path or their unique EC/RSA METHOD pointers.
  */
 struct helper {
 	char *path;
 	pid_t pid;
 	int fd;
 	RSA_METHOD *rsa_meth;
 	EC_KEY_METHOD *ec_meth;
 	int (*rsa_finish)(RSA *rsa);
 	void (*ec_finish)(EC_KEY *key);
 	size_t nrsa, nec; /* number of active keys of each type */
 };
 static struct helper **helpers;
 static size_t nhelpers;

 static struct helper *
 helper_by_provider(const char *path)
 {
 	size_t i;

 	for (i = 0; i < nhelpers; i++) {
 		if (helpers[i] == NULL || helpers[i]->path == NULL ||
 		    helpers[i]->fd == -1)
 			continue;
 		if (strcmp(helpers[i]->path, path) == 0)
 			return helpers[i];
 	}
 	return NULL;
 }

 static struct helper *
 helper_by_rsa(const RSA *rsa)
 {
 	size_t i;
 	const RSA_METHOD *meth;

 	if ((meth = RSA_get_method(rsa)) == NULL)
 		return NULL;
 	for (i = 0; i < nhelpers; i++) {
 		if (helpers[i] != NULL && helpers[i]->rsa_meth == meth)
 			return helpers[i];
 	}
 	return NULL;

 }

 #if defined(OPENSSL_HAS_ECC) && defined(HAVE_EC_KEY_METHOD_NEW)
 static struct helper *
 helper_by_ec(const EC_KEY *ec)
 {
 	size_t i;
 	const EC_KEY_METHOD *meth;

 	if ((meth = EC_KEY_get_method(ec)) == NULL)
 		return NULL;
 	for (i = 0; i < nhelpers; i++) {
 		if (helpers[i] != NULL && helpers[i]->ec_meth == meth)
 			return helpers[i];
 	}
 	return NULL;

 }
 #endif /* defined(OPENSSL_HAS_ECC) && defined(HAVE_EC_KEY_METHOD_NEW) */

 static void
 helper_free(struct helper *helper)
 {
 	size_t i;
 	int found = 0;

 	if (helper == NULL)
 		return;
 	if (helper->path == NULL || helper->ec_meth == NULL ||
 	    helper->rsa_meth == NULL)
 		fatal_f("inconsistent helper");
 	debug3_f("free helper for provider %s", helper->path);
 	for (i = 0; i < nhelpers; i++) {
 		if (helpers[i] == helper) {
 			if (found)
 				fatal_f("helper recorded more than once");
 			found = 1;
 		}
 		else if (found)
 			helpers[i - 1] = helpers[i];
 	}
 	if (found) {
 		helpers = xrecallocarray(helpers, nhelpers,
 		    nhelpers - 1, sizeof(*helpers));
 		nhelpers--;
 	}
 	free(helper->path);
 #if defined(OPENSSL_HAS_ECC) && defined(HAVE_EC_KEY_METHOD_NEW)
 	EC_KEY_METHOD_free(helper->ec_meth);
 #endif
 	RSA_meth_free(helper->rsa_meth);
 	free(helper);
 }

 static void
 helper_terminate(struct helper *helper)
 {
 	if (helper == NULL) {
 		return;
 	} else if (helper->fd == -1) {
 		debug3_f("already terminated");
 	} else {
 		debug3_f("terminating helper for %s; "
 		    "remaining %zu RSA %zu ECDSA",
 		    helper->path, helper->nrsa, helper->nec);
 		close(helper->fd);
 		/* XXX waitpid() */
 		helper->fd = -1;
 		helper->pid = -1;
 	}
 	/*
 	 * Don't delete the helper entry until there are no remaining keys
 	 * that reference it. Otherwise, any signing operation would call
 	 * a free'd METHOD pointer and that would be bad.
 	 */
 	if (helper->nrsa == 0 && helper->nec == 0)
 		helper_free(helper);
 }

 static void
 send_msg(int fd, struct sshbuf *m)
 {
 	u_char buf[4];
 	size_t mlen = sshbuf_len(m);
 	int r;

 	if (fd == -1)
 		return;
 	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_fr(r, "consume");
 }

 static int
 recv_msg(int fd, struct sshbuf *m)
 {
 	u_int l, len;
 	u_char c, buf[1024];
 	int r;

 	sshbuf_reset(m);
 	if (fd == -1)
 		return 0; /* XXX */
 	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 */
 	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_fr(r, "sshbuf_put");
 		len -= l;
 	}
 	if ((r = sshbuf_get_u8(m, &c)) != 0)
 		fatal_fr(r, "parse type");
 	return c;
 }

 int
 pkcs11_init(int interactive)
 {
 	return 0;
 }

 void
 pkcs11_terminate(void)
 {
 	size_t i;

 	debug3_f("terminating %zu helpers", nhelpers);
 	for (i = 0; i < nhelpers; i++)
 		helper_terminate(helpers[i]);
 }

 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;
 	struct helper *helper;

 	if ((helper = helper_by_rsa(rsa)) == NULL || helper->fd == -1)
 		fatal_f("no helper for PKCS11 key");
 	debug3_f("signing with PKCS11 provider %s", helper->path);
 	if (padding != RSA_PKCS1_PADDING)
 		goto fail;
 	key = sshkey_new(KEY_UNSPEC);
 	if (key == NULL) {
 		error_f("sshkey_new failed");
 		goto fail;
 	}
 	key->type = KEY_RSA;
 	RSA_up_ref(rsa);
 	key->rsa = rsa;
 	if ((r = sshkey_to_blob(key, &blob, &blen)) != 0) {
 		error_fr(r, "encode key");
 		goto fail;
 	}
 	if ((msg = sshbuf_new()) == NULL)
 		fatal_f("sshbuf_new failed");
 	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_fr(r, "compose");
 	send_msg(helper->fd, msg);
 	sshbuf_reset(msg);

 	if (recv_msg(helper->fd, msg) == SSH2_AGENT_SIGN_RESPONSE) {
 		if ((r = sshbuf_get_string(msg, &signature, &slen)) != 0)
 			fatal_fr(r, "parse");
 		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);
 }

 static int
 rsa_finish(RSA *rsa)
 {
 	struct helper *helper;

 	if ((helper = helper_by_rsa(rsa)) == NULL)
 		fatal_f("no helper for PKCS11 key");
 	debug3_f("free PKCS11 RSA key for provider %s", helper->path);
 	if (helper->rsa_finish != NULL)
 		helper->rsa_finish(rsa);
 	if (helper->nrsa == 0)
 		fatal_f("RSA refcount error");
 	helper->nrsa--;
 	debug3_f("provider %s remaining keys: %zu RSA %zu ECDSA",
 	    helper->path, helper->nrsa, helper->nec);
 	if (helper->nrsa == 0 && helper->nec == 0)
 		helper_terminate(helper);
 	return 1;
 }

 #if defined(OPENSSL_HAS_ECC) && defined(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;
 	struct helper *helper;

 	if ((helper = helper_by_ec(ec)) == NULL || helper->fd == -1)
 		fatal_f("no helper for PKCS11 key");
 	debug3_f("signing with PKCS11 provider %s", helper->path);
 	nid = sshkey_ecdsa_key_to_nid(ec);
 	if (nid < 0) {
 		error_f("couldn't get curve nid");
 		goto fail;
 	}

 	key = sshkey_new(KEY_UNSPEC);
 	if (key == NULL) {
 		error_f("sshkey_new failed");
 		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_fr(r, "encode key");
 		goto fail;
 	}
 	if ((msg = sshbuf_new()) == NULL)
 		fatal_f("sshbuf_new failed");
 	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_fr(r, "compose");
 	send_msg(helper->fd, msg);
 	sshbuf_reset(msg);

 	if (recv_msg(helper->fd, msg) == SSH2_AGENT_SIGN_RESPONSE) {
 		if ((r = sshbuf_get_string(msg, &signature, &slen)) != 0)
 			fatal_fr(r, "parse");
 		cp = signature;
 		ret = d2i_ECDSA_SIG(NULL, &cp, slen);
 		free(signature);
 	}

  fail:
 	free(blob);
 	sshkey_free(key);
 	sshbuf_free(msg);
 	return (ret);
 }

 static void
 ecdsa_do_finish(EC_KEY *ec)
 {
 	struct helper *helper;

 	if ((helper = helper_by_ec(ec)) == NULL)
 		fatal_f("no helper for PKCS11 key");
 	debug3_f("free PKCS11 ECDSA key for provider %s", helper->path);
 	if (helper->ec_finish != NULL)
 		helper->ec_finish(ec);
 	if (helper->nec == 0)
 		fatal_f("ECDSA refcount error");
 	helper->nec--;
 	debug3_f("provider %s remaining keys: %zu RSA %zu ECDSA",
 	    helper->path, helper->nrsa, helper->nec);
 	if (helper->nrsa == 0 && helper->nec == 0)
 		helper_terminate(helper);
 }
 #endif /* defined(OPENSSL_HAS_ECC) && defined(HAVE_EC_KEY_METHOD_NEW) */

 /* redirect private key crypto operations to the ssh-pkcs11-helper */
 static void
 wrap_key(struct helper *helper, struct sshkey *k)
 {
 	debug3_f("wrap %s for provider %s", sshkey_type(k), helper->path);
 	if (k->type == KEY_RSA) {
 		RSA_set_method(k->rsa, helper->rsa_meth);
 		if (helper->nrsa++ >= INT_MAX)
 			fatal_f("RSA refcount error");
 #if defined(OPENSSL_HAS_ECC) && defined(HAVE_EC_KEY_METHOD_NEW)
 	} else if (k->type == KEY_ECDSA) {
 		EC_KEY_set_method(k->ecdsa, helper->ec_meth);
 		if (helper->nec++ >= INT_MAX)
 			fatal_f("EC refcount error");
 #endif
 	} else
 		fatal_f("unknown key type");
 	k->flags |= SSHKEY_FLAG_EXT;
 	debug3_f("provider %s remaining keys: %zu RSA %zu ECDSA",
 	    helper->path, helper->nrsa, helper->nec);
 }

 /*
  * Make a private PKCS#11-backed certificate by grafting a previously-loaded
  * PKCS#11 private key and a public certificate key.
  */
 int
 pkcs11_make_cert(const struct sshkey *priv,
     const struct sshkey *certpub, struct sshkey **certprivp)
 {
 	struct helper *helper = NULL;
 	struct sshkey *ret;
 	int r;

 	debug3_f("private key type %s cert type %s", sshkey_type(priv),
 	    sshkey_type(certpub));
 	*certprivp = NULL;
 	if (!sshkey_is_cert(certpub) || sshkey_is_cert(priv) ||
 	    !sshkey_equal_public(priv, certpub)) {
 		error_f("private key %s doesn't match cert %s",
 		    sshkey_type(priv), sshkey_type(certpub));
 		return SSH_ERR_INVALID_ARGUMENT;
 	}
 	*certprivp = NULL;
 	if (priv->type == KEY_RSA) {
 		if ((helper = helper_by_rsa(priv->rsa)) == NULL ||
 		    helper->fd == -1)
 			fatal_f("no helper for PKCS11 RSA key");
 		if ((r = sshkey_from_private(priv, &ret)) != 0)
 			fatal_fr(r, "copy key");
 		RSA_set_method(ret->rsa, helper->rsa_meth);
 		if (helper->nrsa++ >= INT_MAX)
 			fatal_f("RSA refcount error");
 	} else if (priv->type == KEY_ECDSA) {
 		if ((helper = helper_by_ec(priv->ecdsa)) == NULL ||
 		    helper->fd == -1)
 			fatal_f("no helper for PKCS11 EC key");
 		if ((r = sshkey_from_private(priv, &ret)) != 0)
 			fatal_fr(r, "copy key");
 		EC_KEY_set_method(ret->ecdsa, helper->ec_meth);
 		if (helper->nec++ >= INT_MAX)
 			fatal_f("EC refcount error");
 	} else
 		fatal_f("unknown key type %s", sshkey_type(priv));

 	ret->flags |= SSHKEY_FLAG_EXT;
 	if ((r = sshkey_to_certified(ret)) != 0 ||
 	    (r = sshkey_cert_copy(certpub, ret)) != 0)
 		fatal_fr(r, "graft certificate");
 	debug3_f("provider %s remaining keys: %zu RSA %zu ECDSA",
 	    helper->path, helper->nrsa, helper->nec);
 	/* success */
 	*certprivp = ret;
 	return 0;
 }

 static int
 pkcs11_start_helper_methods(struct helper *helper)
 {
 	RSA_METHOD *rsa_meth;
 	EC_KEY_METHOD *ec_meth = NULL;
 #if defined(OPENSSL_HAS_ECC) && defined(HAVE_EC_KEY_METHOD_NEW)
 	int (*ec_init)(EC_KEY *key);
 	int (*ec_copy)(EC_KEY *dest, const EC_KEY *src);
 	int (*ec_set_group)(EC_KEY *key, const EC_GROUP *grp);
 	int (*ec_set_private)(EC_KEY *key, const BIGNUM *priv_key);
 	int (*ec_set_public)(EC_KEY *key, const EC_POINT *pub_key);
 	int (*ec_sign)(int, const unsigned char *, int, unsigned char *,
 	    unsigned int *, const BIGNUM *, const BIGNUM *, EC_KEY *) = NULL;

 	if ((ec_meth = EC_KEY_METHOD_new(EC_KEY_OpenSSL())) == NULL)
 		return -1;
 	EC_KEY_METHOD_get_sign(ec_meth, &ec_sign, NULL, NULL);
 	EC_KEY_METHOD_set_sign(ec_meth, ec_sign, NULL, ecdsa_do_sign);
 	EC_KEY_METHOD_get_init(ec_meth, &ec_init, &helper->ec_finish,
 	    &ec_copy, &ec_set_group, &ec_set_private, &ec_set_public);
 	EC_KEY_METHOD_set_init(ec_meth, ec_init, ecdsa_do_finish,
 	    ec_copy, ec_set_group, ec_set_private, ec_set_public);
 #endif /* defined(OPENSSL_HAS_ECC) && defined(HAVE_EC_KEY_METHOD_NEW) */

 	if ((rsa_meth = RSA_meth_dup(RSA_get_default_method())) == NULL)
 		fatal_f("RSA_meth_dup failed");
 	helper->rsa_finish = RSA_meth_get_finish(rsa_meth);
 	if (!RSA_meth_set1_name(rsa_meth, "ssh-pkcs11-helper") ||
 	    !RSA_meth_set_priv_enc(rsa_meth, rsa_encrypt) ||
 	    !RSA_meth_set_finish(rsa_meth, rsa_finish))
 		fatal_f("failed to prepare method");

 	helper->ec_meth = ec_meth;
 	helper->rsa_meth = rsa_meth;
 	return 0;
 }

 static struct helper *
 pkcs11_start_helper(const char *path)
 {
 	int pair[2];
 	char *prog, *verbosity = NULL;
 	struct helper *helper;
 	pid_t pid;

 	if (nhelpers >= INT_MAX)
 		fatal_f("too many helpers");
 	debug3_f("start helper for %s", path);
 	if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1) {
 		error_f("socketpair: %s", strerror(errno));
 		return NULL;
 	}
 	helper = xcalloc(1, sizeof(*helper));
 	if (pkcs11_start_helper_methods(helper) == -1) {
 		error_f("pkcs11_start_helper_methods failed");
 		goto fail;
 	}
 	if ((pid = fork()) == -1) {
 		error_f("fork: %s", strerror(errno));
  fail:
 		close(pair[0]);
 		close(pair[1]);
 		RSA_meth_free(helper->rsa_meth);
 #if defined(OPENSSL_HAS_ECC) && defined(HAVE_EC_KEY_METHOD_NEW)
 		EC_KEY_METHOD_free(helper->ec_meth);
 #endif
 		free(helper);
 		return NULL;
 	} 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]);
 		prog = getenv("SSH_PKCS11_HELPER");
 		if (prog == NULL || strlen(prog) == 0)
 			prog = _PATH_SSH_PKCS11_HELPER;
 		if (log_level_get() >= SYSLOG_LEVEL_DEBUG1)
 			verbosity = "-vvv";
 		debug_f("starting %s %s", prog,
 		    verbosity == NULL ? "" : verbosity);
 		execlp(prog, prog, verbosity, (char *)NULL);
 		fprintf(stderr, "exec: %s: %s\n", prog, strerror(errno));
 		_exit(1);
 	}
 	close(pair[1]);
 	helper->fd = pair[0];
 	helper->path = xstrdup(path);
 	helper->pid = pid;
 	debug3_f("helper %zu for \"%s\" on fd %d pid %ld", nhelpers,
 	    helper->path, helper->fd, (long)helper->pid);
 	helpers = xrecallocarray(helpers, nhelpers,
 	    nhelpers + 1, sizeof(*helpers));
 	helpers[nhelpers++] = helper;
 	return helper;
 }

 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;
 	struct helper *helper;

 	if ((helper = helper_by_provider(name)) == NULL &&
 	    (helper = pkcs11_start_helper(name)) == NULL)
 		return -1;

 	if ((msg = sshbuf_new()) == NULL)
 		fatal_f("sshbuf_new failed");
 	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_fr(r, "compose");
 	send_msg(helper->fd, msg);
 	sshbuf_reset(msg);

 	type = recv_msg(helper->fd, msg);
 	if (type == SSH2_AGENT_IDENTITIES_ANSWER) {
 		if ((r = sshbuf_get_u32(msg, &nkeys)) != 0)
 			fatal_fr(r, "parse nkeys");
 		*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_fr(r, "parse key");
 			if ((r = sshkey_from_blob(blob, blen, &k)) != 0)
 				fatal_fr(r, "decode key");
 			wrap_key(helper, 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)
 {
 	struct helper *helper;

 	/*
 	 * ssh-agent deletes keys before calling this, so the helper entry
 	 * should be gone before we get here.
 	 */
 	debug3_f("delete %s", name);
 	if ((helper = helper_by_provider(name)) != NULL)
 		helper_terminate(helper);
 	return 0;
 }
 #endif /* ENABLE_PKCS11 */
	/* $OpenBSD: ssh-pkcs11-client.c,v 1.19 2023/12/18 14:46:56 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 <limits.h>

	#include <openssl/ecdsa.h>
	#include <openssl/rsa.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"

	#include "openbsd-compat/openssl-compat.h"

	#if !defined(OPENSSL_HAS_ECC) \|\| !defined(HAVE_EC_KEY_METHOD_NEW)
	#define EC_KEY_METHOD void
	#define EC_KEY void
	#endif

	/* borrows code from sftp-server and ssh-agent */

	/*
	* Maintain a list of ssh-pkcs11-helper subprocesses. These may be looked up
	* by provider path or their unique EC/RSA METHOD pointers.
	*/
	struct helper {
	char *path;
	pid_t pid;
	int fd;
	RSA_METHOD *rsa_meth;
	EC_KEY_METHOD *ec_meth;
	int (rsa_finish)(RSA rsa);
	void (ec_finish)(EC_KEY key);
	size_t nrsa, nec; /* number of active keys of each type */
	};
	static struct helper **helpers;
	static size_t nhelpers;

	static struct helper *
	helper_by_provider(const char *path)
	{
	size_t i;

	for (i = 0; i < nhelpers; i++) {
	if (helpers[i] == NULL \|\| helpers[i]->path == NULL \|\|
	helpers[i]->fd == -1)
	continue;
	if (strcmp(helpers[i]->path, path) == 0)
	return helpers[i];
	}
	return NULL;
	}

	static struct helper *
	helper_by_rsa(const RSA *rsa)
	{
	size_t i;
	const RSA_METHOD *meth;

	if ((meth = RSA_get_method(rsa)) == NULL)
	return NULL;
	for (i = 0; i < nhelpers; i++) {
	if (helpers[i] != NULL && helpers[i]->rsa_meth == meth)
	return helpers[i];
	}
	return NULL;

	}

	#if defined(OPENSSL_HAS_ECC) && defined(HAVE_EC_KEY_METHOD_NEW)
	static struct helper *
	helper_by_ec(const EC_KEY *ec)
	{
	size_t i;
	const EC_KEY_METHOD *meth;

	if ((meth = EC_KEY_get_method(ec)) == NULL)
	return NULL;
	for (i = 0; i < nhelpers; i++) {
	if (helpers[i] != NULL && helpers[i]->ec_meth == meth)
	return helpers[i];
	}
	return NULL;

	}
	#endif /* defined(OPENSSL_HAS_ECC) && defined(HAVE_EC_KEY_METHOD_NEW) */

	static void
	helper_free(struct helper *helper)
	{
	size_t i;
	int found = 0;

	if (helper == NULL)
	return;
	if (helper->path == NULL \|\| helper->ec_meth == NULL \|\|
	helper->rsa_meth == NULL)
	fatal_f("inconsistent helper");
	debug3_f("free helper for provider %s", helper->path);
	for (i = 0; i < nhelpers; i++) {
	if (helpers[i] == helper) {
	if (found)
	fatal_f("helper recorded more than once");
	found = 1;
	}
	else if (found)
	helpers[i - 1] = helpers[i];
	}
	if (found) {
	helpers = xrecallocarray(helpers, nhelpers,
	nhelpers - 1, sizeof(*helpers));
	nhelpers--;
	}
	free(helper->path);
	#if defined(OPENSSL_HAS_ECC) && defined(HAVE_EC_KEY_METHOD_NEW)
	EC_KEY_METHOD_free(helper->ec_meth);
	#endif
	RSA_meth_free(helper->rsa_meth);
	free(helper);
	}

	static void
	helper_terminate(struct helper *helper)
	{
	if (helper == NULL) {
	return;
	} else if (helper->fd == -1) {
	debug3_f("already terminated");
	} else {
	debug3_f("terminating helper for %s; "
	"remaining %zu RSA %zu ECDSA",
	helper->path, helper->nrsa, helper->nec);
	close(helper->fd);
	/* XXX waitpid() */
	helper->fd = -1;
	helper->pid = -1;
	}
	/*
	* Don't delete the helper entry until there are no remaining keys
	* that reference it. Otherwise, any signing operation would call
	* a free'd METHOD pointer and that would be bad.
	*/
	if (helper->nrsa == 0 && helper->nec == 0)
	helper_free(helper);
	}

	static void
	send_msg(int fd, struct sshbuf *m)
	{
	u_char buf[4];
	size_t mlen = sshbuf_len(m);
	int r;

	if (fd == -1)
	return;
	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_fr(r, "consume");
	}

	static int
	recv_msg(int fd, struct sshbuf *m)
	{
	u_int l, len;
	u_char c, buf[1024];
	int r;

	sshbuf_reset(m);
	if (fd == -1)
	return 0; /* XXX */
	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 */
	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_fr(r, "sshbuf_put");
	len -= l;
	}
	if ((r = sshbuf_get_u8(m, &c)) != 0)
	fatal_fr(r, "parse type");
	return c;
	}

	int
	pkcs11_init(int interactive)
	{
	return 0;
	}

	void
	pkcs11_terminate(void)
	{
	size_t i;

	debug3_f("terminating %zu helpers", nhelpers);
	for (i = 0; i < nhelpers; i++)
	helper_terminate(helpers[i]);
	}

	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;
	struct helper *helper;

	if ((helper = helper_by_rsa(rsa)) == NULL \|\| helper->fd == -1)
	fatal_f("no helper for PKCS11 key");
	debug3_f("signing with PKCS11 provider %s", helper->path);
	if (padding != RSA_PKCS1_PADDING)
	goto fail;
	key = sshkey_new(KEY_UNSPEC);
	if (key == NULL) {
	error_f("sshkey_new failed");
	goto fail;
	}
	key->type = KEY_RSA;
	RSA_up_ref(rsa);
	key->rsa = rsa;
	if ((r = sshkey_to_blob(key, &blob, &blen)) != 0) {
	error_fr(r, "encode key");
	goto fail;
	}
	if ((msg = sshbuf_new()) == NULL)
	fatal_f("sshbuf_new failed");
	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_fr(r, "compose");
	send_msg(helper->fd, msg);
	sshbuf_reset(msg);

	if (recv_msg(helper->fd, msg) == SSH2_AGENT_SIGN_RESPONSE) {
	if ((r = sshbuf_get_string(msg, &signature, &slen)) != 0)
	fatal_fr(r, "parse");
	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);
	}

	static int
	rsa_finish(RSA *rsa)
	{
	struct helper *helper;

	if ((helper = helper_by_rsa(rsa)) == NULL)
	fatal_f("no helper for PKCS11 key");
	debug3_f("free PKCS11 RSA key for provider %s", helper->path);
	if (helper->rsa_finish != NULL)
	helper->rsa_finish(rsa);
	if (helper->nrsa == 0)
	fatal_f("RSA refcount error");
	helper->nrsa--;
	debug3_f("provider %s remaining keys: %zu RSA %zu ECDSA",
	helper->path, helper->nrsa, helper->nec);
	if (helper->nrsa == 0 && helper->nec == 0)
	helper_terminate(helper);
	return 1;
	}

	#if defined(OPENSSL_HAS_ECC) && defined(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;
	struct helper *helper;

	if ((helper = helper_by_ec(ec)) == NULL \|\| helper->fd == -1)
	fatal_f("no helper for PKCS11 key");
	debug3_f("signing with PKCS11 provider %s", helper->path);
	nid = sshkey_ecdsa_key_to_nid(ec);
	if (nid < 0) {
	error_f("couldn't get curve nid");
	goto fail;
	}

	key = sshkey_new(KEY_UNSPEC);
	if (key == NULL) {
	error_f("sshkey_new failed");
	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_fr(r, "encode key");
	goto fail;
	}
	if ((msg = sshbuf_new()) == NULL)
	fatal_f("sshbuf_new failed");
	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_fr(r, "compose");
	send_msg(helper->fd, msg);
	sshbuf_reset(msg);

	if (recv_msg(helper->fd, msg) == SSH2_AGENT_SIGN_RESPONSE) {
	if ((r = sshbuf_get_string(msg, &signature, &slen)) != 0)
	fatal_fr(r, "parse");
	cp = signature;
	ret = d2i_ECDSA_SIG(NULL, &cp, slen);
	free(signature);
	}

	fail:
	free(blob);
	sshkey_free(key);
	sshbuf_free(msg);
	return (ret);
	}

	static void
	ecdsa_do_finish(EC_KEY *ec)
	{
	struct helper *helper;

	if ((helper = helper_by_ec(ec)) == NULL)
	fatal_f("no helper for PKCS11 key");
	debug3_f("free PKCS11 ECDSA key for provider %s", helper->path);
	if (helper->ec_finish != NULL)
	helper->ec_finish(ec);
	if (helper->nec == 0)
	fatal_f("ECDSA refcount error");
	helper->nec--;
	debug3_f("provider %s remaining keys: %zu RSA %zu ECDSA",
	helper->path, helper->nrsa, helper->nec);
	if (helper->nrsa == 0 && helper->nec == 0)
	helper_terminate(helper);
	}
	#endif /* defined(OPENSSL_HAS_ECC) && defined(HAVE_EC_KEY_METHOD_NEW) */

	/* redirect private key crypto operations to the ssh-pkcs11-helper */
	static void
	wrap_key(struct helper helper, struct sshkey k)
	{
	debug3_f("wrap %s for provider %s", sshkey_type(k), helper->path);
	if (k->type == KEY_RSA) {
	RSA_set_method(k->rsa, helper->rsa_meth);
	if (helper->nrsa++ >= INT_MAX)
	fatal_f("RSA refcount error");
	#if defined(OPENSSL_HAS_ECC) && defined(HAVE_EC_KEY_METHOD_NEW)
	} else if (k->type == KEY_ECDSA) {
	EC_KEY_set_method(k->ecdsa, helper->ec_meth);
	if (helper->nec++ >= INT_MAX)
	fatal_f("EC refcount error");
	#endif
	} else
	fatal_f("unknown key type");
	k->flags \|= SSHKEY_FLAG_EXT;
	debug3_f("provider %s remaining keys: %zu RSA %zu ECDSA",
	helper->path, helper->nrsa, helper->nec);
	}

	/*
	* Make a private PKCS#11-backed certificate by grafting a previously-loaded
	* PKCS#11 private key and a public certificate key.
	*/
	int
	pkcs11_make_cert(const struct sshkey *priv,
	const struct sshkey certpub, struct sshkey *certprivp)
	{
	struct helper *helper = NULL;
	struct sshkey *ret;
	int r;

	debug3_f("private key type %s cert type %s", sshkey_type(priv),
	sshkey_type(certpub));
	*certprivp = NULL;
	if (!sshkey_is_cert(certpub) \|\| sshkey_is_cert(priv) \|\|
	!sshkey_equal_public(priv, certpub)) {
	error_f("private key %s doesn't match cert %s",
	sshkey_type(priv), sshkey_type(certpub));
	return SSH_ERR_INVALID_ARGUMENT;
	}
	*certprivp = NULL;
	if (priv->type == KEY_RSA) {
	if ((helper = helper_by_rsa(priv->rsa)) == NULL \|\|
	helper->fd == -1)
	fatal_f("no helper for PKCS11 RSA key");
	if ((r = sshkey_from_private(priv, &ret)) != 0)
	fatal_fr(r, "copy key");
	RSA_set_method(ret->rsa, helper->rsa_meth);
	if (helper->nrsa++ >= INT_MAX)
	fatal_f("RSA refcount error");
	} else if (priv->type == KEY_ECDSA) {
	if ((helper = helper_by_ec(priv->ecdsa)) == NULL \|\|
	helper->fd == -1)
	fatal_f("no helper for PKCS11 EC key");
	if ((r = sshkey_from_private(priv, &ret)) != 0)
	fatal_fr(r, "copy key");
	EC_KEY_set_method(ret->ecdsa, helper->ec_meth);
	if (helper->nec++ >= INT_MAX)
	fatal_f("EC refcount error");
	} else
	fatal_f("unknown key type %s", sshkey_type(priv));

	ret->flags \|= SSHKEY_FLAG_EXT;
	if ((r = sshkey_to_certified(ret)) != 0 \|\|
	(r = sshkey_cert_copy(certpub, ret)) != 0)
	fatal_fr(r, "graft certificate");
	debug3_f("provider %s remaining keys: %zu RSA %zu ECDSA",
	helper->path, helper->nrsa, helper->nec);
	/* success */
	*certprivp = ret;
	return 0;
	}

	static int
	pkcs11_start_helper_methods(struct helper *helper)
	{
	RSA_METHOD *rsa_meth;
	EC_KEY_METHOD *ec_meth = NULL;
	#if defined(OPENSSL_HAS_ECC) && defined(HAVE_EC_KEY_METHOD_NEW)
	int (ec_init)(EC_KEY key);
	int (ec_copy)(EC_KEY dest, const EC_KEY *src);
	int (ec_set_group)(EC_KEY key, const EC_GROUP *grp);
	int (ec_set_private)(EC_KEY key, const BIGNUM *priv_key);
	int (ec_set_public)(EC_KEY key, const EC_POINT *pub_key);
	int (ec_sign)(int, const unsigned char , int, unsigned char *,
	unsigned int , const BIGNUM , const BIGNUM , EC_KEY ) = NULL;

	if ((ec_meth = EC_KEY_METHOD_new(EC_KEY_OpenSSL())) == NULL)
	return -1;
	EC_KEY_METHOD_get_sign(ec_meth, &ec_sign, NULL, NULL);
	EC_KEY_METHOD_set_sign(ec_meth, ec_sign, NULL, ecdsa_do_sign);
	EC_KEY_METHOD_get_init(ec_meth, &ec_init, &helper->ec_finish,
	&ec_copy, &ec_set_group, &ec_set_private, &ec_set_public);
	EC_KEY_METHOD_set_init(ec_meth, ec_init, ecdsa_do_finish,
	ec_copy, ec_set_group, ec_set_private, ec_set_public);
	#endif /* defined(OPENSSL_HAS_ECC) && defined(HAVE_EC_KEY_METHOD_NEW) */

	if ((rsa_meth = RSA_meth_dup(RSA_get_default_method())) == NULL)
	fatal_f("RSA_meth_dup failed");
	helper->rsa_finish = RSA_meth_get_finish(rsa_meth);
	if (!RSA_meth_set1_name(rsa_meth, "ssh-pkcs11-helper") \|\|
	!RSA_meth_set_priv_enc(rsa_meth, rsa_encrypt) \|\|
	!RSA_meth_set_finish(rsa_meth, rsa_finish))
	fatal_f("failed to prepare method");

	helper->ec_meth = ec_meth;
	helper->rsa_meth = rsa_meth;
	return 0;
	}

	static struct helper *
	pkcs11_start_helper(const char *path)
	{
	int pair[2];
	char prog, verbosity = NULL;
	struct helper *helper;
	pid_t pid;

	if (nhelpers >= INT_MAX)
	fatal_f("too many helpers");
	debug3_f("start helper for %s", path);
	if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1) {
	error_f("socketpair: %s", strerror(errno));
	return NULL;
	}
	helper = xcalloc(1, sizeof(*helper));
	if (pkcs11_start_helper_methods(helper) == -1) {
	error_f("pkcs11_start_helper_methods failed");
	goto fail;
	}
	if ((pid = fork()) == -1) {
	error_f("fork: %s", strerror(errno));
	fail:
	close(pair[0]);
	close(pair[1]);
	RSA_meth_free(helper->rsa_meth);
	#if defined(OPENSSL_HAS_ECC) && defined(HAVE_EC_KEY_METHOD_NEW)
	EC_KEY_METHOD_free(helper->ec_meth);
	#endif
	free(helper);
	return NULL;
	} 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]);
	prog = getenv("SSH_PKCS11_HELPER");
	if (prog == NULL \|\| strlen(prog) == 0)
	prog = _PATH_SSH_PKCS11_HELPER;
	if (log_level_get() >= SYSLOG_LEVEL_DEBUG1)
	verbosity = "-vvv";
	debug_f("starting %s %s", prog,
	verbosity == NULL ? "" : verbosity);
	execlp(prog, prog, verbosity, (char *)NULL);
	fprintf(stderr, "exec: %s: %s\n", prog, strerror(errno));
	_exit(1);
	}
	close(pair[1]);
	helper->fd = pair[0];
	helper->path = xstrdup(path);
	helper->pid = pid;
	debug3_f("helper %zu for \"%s\" on fd %d pid %ld", nhelpers,
	helper->path, helper->fd, (long)helper->pid);
	helpers = xrecallocarray(helpers, nhelpers,
	nhelpers + 1, sizeof(*helpers));
	helpers[nhelpers++] = helper;
	return helper;
	}

	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;
	struct helper *helper;

	if ((helper = helper_by_provider(name)) == NULL &&
	(helper = pkcs11_start_helper(name)) == NULL)
	return -1;

	if ((msg = sshbuf_new()) == NULL)
	fatal_f("sshbuf_new failed");
	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_fr(r, "compose");
	send_msg(helper->fd, msg);
	sshbuf_reset(msg);

	type = recv_msg(helper->fd, msg);
	if (type == SSH2_AGENT_IDENTITIES_ANSWER) {
	if ((r = sshbuf_get_u32(msg, &nkeys)) != 0)
	fatal_fr(r, "parse nkeys");
	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_fr(r, "parse key");
	if ((r = sshkey_from_blob(blob, blen, &k)) != 0)
	fatal_fr(r, "decode key");
	wrap_key(helper, 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)
	{
	struct helper *helper;

	/*
	* ssh-agent deletes keys before calling this, so the helper entry
	* should be gone before we get here.
	*/
	debug3_f("delete %s", name);
	if ((helper = helper_by_provider(name)) != NULL)
	helper_terminate(helper);
	return 0;
	}
	#endif /* ENABLE_PKCS11 */