Adding upstream version 1:9.6p1.upstream/1%9.6p1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 654 insertions, 0 deletions

diff --git a/ssh-pkcs11-client.c b/ssh-pkcs11-client.c
new file mode 100644
index 0000000..82e86a5
--- /dev/null
+++ b/ssh-pkcs11-client.c
@@ -0,0 +1,654 @@
+/* $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 */