-/* $OpenBSD: ssh-pkcs11-client.c,v 1.17 2020/10/18 11:32:02 djm Exp $ */
+/* $OpenBSD: ssh-pkcs11-client.c,v 1.18 2023/07/19 14:03:45 djm Exp $ */
/*
* Copyright (c) 2010 Markus Friedl. All rights reserved.
* Copyright (c) 2014 Pedro Martelletto. All rights reserved.
#include <string.h>
#include <unistd.h>
#include <errno.h>
+#include <limits.h>
#include <openssl/ecdsa.h>
#include <openssl/rsa.h>
/* borrows code from sftp-server and ssh-agent */
-static int fd = -1;
-static pid_t pid = -1;
+/*
+ * 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;
+
+}
+
+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;
+
+}
static void
-send_msg(struct sshbuf *m)
+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);
+ EC_KEY_METHOD_free(helper->ec_meth);
+ 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),
}
static int
-recv_msg(struct sshbuf *m)
+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 */
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))
int
pkcs11_init(int interactive)
{
- return (0);
+ return 0;
}
void
pkcs11_terminate(void)
{
- if (fd >= 0)
- close(fd);
+ size_t i;
+
+ debug3_f("terminating %zu helpers", nhelpers);
+ for (i = 0; i < nhelpers; i++)
+ helper_terminate(helpers[i]);
}
static int
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);
(r = sshbuf_put_string(msg, from, flen)) != 0 ||
(r = sshbuf_put_u32(msg, 0)) != 0)
fatal_fr(r, "compose");
- send_msg(msg);
+ send_msg(helper->fd, msg);
sshbuf_reset(msg);
- if (recv_msg(msg) == SSH2_AGENT_SIGN_RESPONSE) {
+ 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)) {
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;
+}
+
static ECDSA_SIG *
ecdsa_do_sign(const unsigned char *dgst, int dgst_len, const BIGNUM *inv,
const BIGNUM *rp, EC_KEY *ec)
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");
(r = sshbuf_put_string(msg, dgst, dgst_len)) != 0 ||
(r = sshbuf_put_u32(msg, 0)) != 0)
fatal_fr(r, "compose");
- send_msg(msg);
+ send_msg(helper->fd, msg);
sshbuf_reset(msg);
- if (recv_msg(msg) == SSH2_AGENT_SIGN_RESPONSE) {
+ 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;
return (ret);
}
-static RSA_METHOD *helper_rsa;
-static EC_KEY_METHOD *helper_ecdsa;
+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);
+}
/* redirect private key crypto operations to the ssh-pkcs11-helper */
static void
-wrap_key(struct sshkey *k)
+wrap_key(struct helper *helper, struct sshkey *k)
{
- if (k->type == KEY_RSA)
- RSA_set_method(k->rsa, helper_rsa);
- else if (k->type == KEY_ECDSA)
- EC_KEY_set_method(k->ecdsa, helper_ecdsa);
- else
+ 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");
+ } 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");
+ } 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);
}
static int
-pkcs11_start_helper_methods(void)
+pkcs11_start_helper_methods(struct helper *helper)
{
- if (helper_ecdsa != NULL)
- return (0);
-
- int (*orig_sign)(int, const unsigned char *, int, unsigned char *,
+ 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 (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);
-
- if ((helper_rsa = RSA_meth_dup(RSA_get_default_method())) == NULL)
+ RSA_METHOD *rsa_meth;
+ EC_KEY_METHOD *ec_meth;
+
+ 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);
+
+ if ((rsa_meth = RSA_meth_dup(RSA_get_default_method())) == NULL)
fatal_f("RSA_meth_dup failed");
- if (!RSA_meth_set1_name(helper_rsa, "ssh-pkcs11-helper") ||
- !RSA_meth_set_priv_enc(helper_rsa, rsa_encrypt))
+ 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");
- return (0);
+ helper->ec_meth = ec_meth;
+ helper->rsa_meth = rsa_meth;
+ return 0;
}
-static int
-pkcs11_start_helper(void)
+static struct helper *
+pkcs11_start_helper(const char *path)
{
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);
- }
+ 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("socketpair: %s", strerror(errno));
- return (-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("fork: %s", strerror(errno));
- return (-1);
+ error_f("fork: %s", strerror(errno));
+ fail:
+ close(pair[0]);
+ close(pair[1]);
+ RSA_meth_free(helper->rsa_meth);
+ EC_KEY_METHOD_free(helper->ec_meth);
+ free(helper);
+ return NULL;
} else if (pid == 0) {
if ((dup2(pair[1], STDIN_FILENO) == -1) ||
(dup2(pair[1], STDOUT_FILENO) == -1)) {
}
close(pair[0]);
close(pair[1]);
- helper = getenv("SSH_PKCS11_HELPER");
- if (helper == NULL || strlen(helper) == 0)
- helper = _PATH_SSH_PKCS11_HELPER;
- debug_f("starting %s %s", helper,
+ 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(helper, helper, verbosity, (char *)NULL);
- fprintf(stderr, "exec: %s: %s\n", helper, strerror(errno));
+ execlp(prog, prog, verbosity, (char *)NULL);
+ fprintf(stderr, "exec: %s: %s\n", prog, strerror(errno));
_exit(1);
}
close(pair[1]);
- fd = pair[0];
- return (0);
+ 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
size_t blen;
u_int nkeys, i;
struct sshbuf *msg;
+ struct helper *helper;
- if (fd < 0 && pkcs11_start_helper() < 0)
- return (-1);
+ 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");
(r = sshbuf_put_cstring(msg, name)) != 0 ||
(r = sshbuf_put_cstring(msg, pin)) != 0)
fatal_fr(r, "compose");
- send_msg(msg);
+ send_msg(helper->fd, msg);
sshbuf_reset(msg);
- type = recv_msg(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");
fatal_fr(r, "parse key");
if ((r = sshkey_from_blob(blob, blen, &k)) != 0)
fatal_fr(r, "decode key");
- wrap_key(k);
+ wrap_key(helper, k);
(*keysp)[i] = k;
if (labelsp)
(*labelsp)[i] = label;
int
pkcs11_del_provider(char *name)
{
- int r, ret = -1;
- struct sshbuf *msg;
-
- if ((msg = sshbuf_new()) == NULL)
- fatal_f("sshbuf_new failed");
- 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_fr(r, "compose");
- send_msg(msg);
- sshbuf_reset(msg);
-
- if (recv_msg(msg) == SSH_AGENT_SUCCESS)
- ret = 0;
- sshbuf_free(msg);
- return (ret);
+ 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;
}
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