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-rw-r--r--ssh-pkcs11-helper.c446
1 files changed, 446 insertions, 0 deletions
diff --git a/ssh-pkcs11-helper.c b/ssh-pkcs11-helper.c
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+++ b/ssh-pkcs11-helper.c
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+/* $OpenBSD: ssh-pkcs11-helper.c,v 1.26 2021/11/18 03:31:44 djm Exp $ */
+/*
+ * 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 "includes.h"
+
+#include <sys/types.h>
+#ifdef HAVE_SYS_TIME_H
+# include <sys/time.h>
+#endif
+
+#include "openbsd-compat/sys-queue.h"
+
+#include <stdlib.h>
+#include <errno.h>
+#ifdef HAVE_POLL_H
+#include <poll.h>
+#endif
+#include <stdarg.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "xmalloc.h"
+#include "sshbuf.h"
+#include "log.h"
+#include "misc.h"
+#include "sshkey.h"
+#include "authfd.h"
+#include "ssh-pkcs11.h"
+#include "ssherr.h"
+
+#ifdef ENABLE_PKCS11
+
+#ifdef WITH_OPENSSL
+
+/* borrows code from sftp-server and ssh-agent */
+
+struct pkcs11_keyinfo {
+ struct sshkey *key;
+ char *providername, *label;
+ TAILQ_ENTRY(pkcs11_keyinfo) next;
+};
+
+TAILQ_HEAD(, pkcs11_keyinfo) pkcs11_keylist;
+
+#define MAX_MSG_LENGTH 10240 /*XXX*/
+
+/* input and output queue */
+struct sshbuf *iqueue;
+struct sshbuf *oqueue;
+
+static void
+add_key(struct sshkey *k, char *name, char *label)
+{
+ struct pkcs11_keyinfo *ki;
+
+ ki = xcalloc(1, sizeof(*ki));
+ ki->providername = xstrdup(name);
+ ki->key = k;
+ ki->label = xstrdup(label);
+ TAILQ_INSERT_TAIL(&pkcs11_keylist, ki, next);
+}
+
+static void
+del_keys_by_name(char *name)
+{
+ struct pkcs11_keyinfo *ki, *nxt;
+
+ for (ki = TAILQ_FIRST(&pkcs11_keylist); ki; ki = nxt) {
+ nxt = TAILQ_NEXT(ki, next);
+ if (!strcmp(ki->providername, name)) {
+ TAILQ_REMOVE(&pkcs11_keylist, ki, next);
+ free(ki->providername);
+ free(ki->label);
+ sshkey_free(ki->key);
+ free(ki);
+ }
+ }
+}
+
+/* lookup matching 'private' key */
+static struct sshkey *
+lookup_key(struct sshkey *k)
+{
+ struct pkcs11_keyinfo *ki;
+
+ TAILQ_FOREACH(ki, &pkcs11_keylist, next) {
+ debug("check %s %s %s", sshkey_type(ki->key),
+ ki->providername, ki->label);
+ if (sshkey_equal(k, ki->key))
+ return (ki->key);
+ }
+ return (NULL);
+}
+
+static void
+send_msg(struct sshbuf *m)
+{
+ int r;
+
+ if ((r = sshbuf_put_stringb(oqueue, m)) != 0)
+ fatal_fr(r, "enqueue");
+}
+
+static void
+process_add(void)
+{
+ char *name, *pin;
+ struct sshkey **keys = NULL;
+ int r, i, nkeys;
+ u_char *blob;
+ size_t blen;
+ struct sshbuf *msg;
+ char **labels = NULL;
+
+ if ((msg = sshbuf_new()) == NULL)
+ fatal_f("sshbuf_new failed");
+ if ((r = sshbuf_get_cstring(iqueue, &name, NULL)) != 0 ||
+ (r = sshbuf_get_cstring(iqueue, &pin, NULL)) != 0)
+ fatal_fr(r, "parse");
+ if ((nkeys = pkcs11_add_provider(name, pin, &keys, &labels)) > 0) {
+ if ((r = sshbuf_put_u8(msg,
+ SSH2_AGENT_IDENTITIES_ANSWER)) != 0 ||
+ (r = sshbuf_put_u32(msg, nkeys)) != 0)
+ fatal_fr(r, "compose");
+ for (i = 0; i < nkeys; i++) {
+ if ((r = sshkey_to_blob(keys[i], &blob, &blen)) != 0) {
+ debug_fr(r, "encode key");
+ continue;
+ }
+ if ((r = sshbuf_put_string(msg, blob, blen)) != 0 ||
+ (r = sshbuf_put_cstring(msg, labels[i])) != 0)
+ fatal_fr(r, "compose key");
+ free(blob);
+ add_key(keys[i], name, labels[i]);
+ free(labels[i]);
+ }
+ } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0 ||
+ (r = sshbuf_put_u32(msg, -nkeys)) != 0)
+ fatal_fr(r, "compose");
+ free(labels);
+ free(keys); /* keys themselves are transferred to pkcs11_keylist */
+ free(pin);
+ free(name);
+ send_msg(msg);
+ sshbuf_free(msg);
+}
+
+static void
+process_del(void)
+{
+ char *name, *pin;
+ struct sshbuf *msg;
+ int r;
+
+ if ((msg = sshbuf_new()) == NULL)
+ fatal_f("sshbuf_new failed");
+ if ((r = sshbuf_get_cstring(iqueue, &name, NULL)) != 0 ||
+ (r = sshbuf_get_cstring(iqueue, &pin, NULL)) != 0)
+ fatal_fr(r, "parse");
+ del_keys_by_name(name);
+ if ((r = sshbuf_put_u8(msg, pkcs11_del_provider(name) == 0 ?
+ SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0)
+ fatal_fr(r, "compose");
+ free(pin);
+ free(name);
+ send_msg(msg);
+ sshbuf_free(msg);
+}
+
+static void
+process_sign(void)
+{
+ u_char *blob, *data, *signature = NULL;
+ size_t blen, dlen, slen = 0;
+ int r, ok = -1;
+ struct sshkey *key, *found;
+ struct sshbuf *msg;
+
+ /* XXX support SHA2 signature flags */
+ if ((r = sshbuf_get_string(iqueue, &blob, &blen)) != 0 ||
+ (r = sshbuf_get_string(iqueue, &data, &dlen)) != 0 ||
+ (r = sshbuf_get_u32(iqueue, NULL)) != 0)
+ fatal_fr(r, "parse");
+
+ if ((r = sshkey_from_blob(blob, blen, &key)) != 0)
+ fatal_fr(r, "decode key");
+ else {
+ if ((found = lookup_key(key)) != NULL) {
+#ifdef WITH_OPENSSL
+ int ret;
+
+ if (key->type == KEY_RSA) {
+ slen = RSA_size(key->rsa);
+ signature = xmalloc(slen);
+ ret = RSA_private_encrypt(dlen, data, signature,
+ found->rsa, RSA_PKCS1_PADDING);
+ if (ret != -1) {
+ slen = ret;
+ ok = 0;
+ }
+#ifdef OPENSSL_HAS_ECC
+ } else if (key->type == KEY_ECDSA) {
+ u_int xslen = ECDSA_size(key->ecdsa);
+
+ signature = xmalloc(xslen);
+ /* "The parameter type is ignored." */
+ ret = ECDSA_sign(-1, data, dlen, signature,
+ &xslen, found->ecdsa);
+ if (ret != 0)
+ ok = 0;
+ else
+ error_f("ECDSA_sign returned %d", ret);
+ slen = xslen;
+#endif /* OPENSSL_HAS_ECC */
+ } else
+ error_f("don't know how to sign with key "
+ "type %d", (int)key->type);
+#endif /* WITH_OPENSSL */
+ }
+ sshkey_free(key);
+ }
+ if ((msg = sshbuf_new()) == NULL)
+ fatal_f("sshbuf_new failed");
+ if (ok == 0) {
+ if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 ||
+ (r = sshbuf_put_string(msg, signature, slen)) != 0)
+ fatal_fr(r, "compose response");
+ } else {
+ if ((r = sshbuf_put_u8(msg, SSH2_AGENT_FAILURE)) != 0)
+ fatal_fr(r, "compose failure response");
+ }
+ free(data);
+ free(blob);
+ free(signature);
+ send_msg(msg);
+ sshbuf_free(msg);
+}
+
+static void
+process(void)
+{
+ u_int msg_len;
+ u_int buf_len;
+ u_int consumed;
+ u_char type;
+ const u_char *cp;
+ int r;
+
+ buf_len = sshbuf_len(iqueue);
+ if (buf_len < 5)
+ return; /* Incomplete message. */
+ cp = sshbuf_ptr(iqueue);
+ msg_len = get_u32(cp);
+ if (msg_len > MAX_MSG_LENGTH) {
+ error("bad message len %d", msg_len);
+ cleanup_exit(11);
+ }
+ if (buf_len < msg_len + 4)
+ return;
+ if ((r = sshbuf_consume(iqueue, 4)) != 0 ||
+ (r = sshbuf_get_u8(iqueue, &type)) != 0)
+ fatal_fr(r, "parse type/len");
+ buf_len -= 4;
+ switch (type) {
+ case SSH_AGENTC_ADD_SMARTCARD_KEY:
+ debug("process_add");
+ process_add();
+ break;
+ case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
+ debug("process_del");
+ process_del();
+ break;
+ case SSH2_AGENTC_SIGN_REQUEST:
+ debug("process_sign");
+ process_sign();
+ break;
+ default:
+ error("Unknown message %d", type);
+ break;
+ }
+ /* discard the remaining bytes from the current packet */
+ if (buf_len < sshbuf_len(iqueue)) {
+ error("iqueue grew unexpectedly");
+ cleanup_exit(255);
+ }
+ consumed = buf_len - sshbuf_len(iqueue);
+ if (msg_len < consumed) {
+ error("msg_len %d < consumed %d", msg_len, consumed);
+ cleanup_exit(255);
+ }
+ if (msg_len > consumed) {
+ if ((r = sshbuf_consume(iqueue, msg_len - consumed)) != 0)
+ fatal_fr(r, "consume");
+ }
+}
+
+void
+cleanup_exit(int i)
+{
+ /* XXX */
+ _exit(i);
+}
+
+
+int
+main(int argc, char **argv)
+{
+ int r, ch, in, out, log_stderr = 0;
+ ssize_t len;
+ SyslogFacility log_facility = SYSLOG_FACILITY_AUTH;
+ LogLevel log_level = SYSLOG_LEVEL_ERROR;
+ char buf[4*4096];
+ extern char *__progname;
+ struct pollfd pfd[2];
+
+ __progname = ssh_get_progname(argv[0]);
+ seed_rng();
+ TAILQ_INIT(&pkcs11_keylist);
+
+ log_init(__progname, log_level, log_facility, log_stderr);
+
+ while ((ch = getopt(argc, argv, "v")) != -1) {
+ switch (ch) {
+ case 'v':
+ log_stderr = 1;
+ if (log_level == SYSLOG_LEVEL_ERROR)
+ log_level = SYSLOG_LEVEL_DEBUG1;
+ else if (log_level < SYSLOG_LEVEL_DEBUG3)
+ log_level++;
+ break;
+ default:
+ fprintf(stderr, "usage: %s [-v]\n", __progname);
+ exit(1);
+ }
+ }
+
+ log_init(__progname, log_level, log_facility, log_stderr);
+
+ pkcs11_init(0);
+ in = STDIN_FILENO;
+ out = STDOUT_FILENO;
+
+ if ((iqueue = sshbuf_new()) == NULL)
+ fatal_f("sshbuf_new failed");
+ if ((oqueue = sshbuf_new()) == NULL)
+ fatal_f("sshbuf_new failed");
+
+ while (1) {
+ memset(pfd, 0, sizeof(pfd));
+ pfd[0].fd = in;
+ pfd[1].fd = out;
+
+ /*
+ * Ensure that we can read a full buffer and handle
+ * the worst-case length packet it can generate,
+ * otherwise apply backpressure by stopping reads.
+ */
+ if ((r = sshbuf_check_reserve(iqueue, sizeof(buf))) == 0 &&
+ (r = sshbuf_check_reserve(oqueue, MAX_MSG_LENGTH)) == 0)
+ pfd[0].events = POLLIN;
+ else if (r != SSH_ERR_NO_BUFFER_SPACE)
+ fatal_fr(r, "reserve");
+
+ if (sshbuf_len(oqueue) > 0)
+ pfd[1].events = POLLOUT;
+
+ if ((r = poll(pfd, 2, -1 /* INFTIM */)) <= 0) {
+ if (r == 0 || errno == EINTR)
+ continue;
+ fatal("poll: %s", strerror(errno));
+ }
+
+ /* copy stdin to iqueue */
+ if ((pfd[0].revents & (POLLIN|POLLHUP|POLLERR)) != 0) {
+ len = read(in, buf, sizeof buf);
+ if (len == 0) {
+ debug("read eof");
+ cleanup_exit(0);
+ } else if (len < 0) {
+ error("read: %s", strerror(errno));
+ cleanup_exit(1);
+ } else if ((r = sshbuf_put(iqueue, buf, len)) != 0)
+ fatal_fr(r, "sshbuf_put");
+ }
+ /* send oqueue to stdout */
+ if ((pfd[1].revents & (POLLOUT|POLLHUP)) != 0) {
+ len = write(out, sshbuf_ptr(oqueue),
+ sshbuf_len(oqueue));
+ if (len < 0) {
+ error("write: %s", strerror(errno));
+ cleanup_exit(1);
+ } else if ((r = sshbuf_consume(oqueue, len)) != 0)
+ fatal_fr(r, "consume");
+ }
+
+ /*
+ * Process requests from client if we can fit the results
+ * into the output buffer, otherwise stop processing input
+ * and let the output queue drain.
+ */
+ if ((r = sshbuf_check_reserve(oqueue, MAX_MSG_LENGTH)) == 0)
+ process();
+ else if (r != SSH_ERR_NO_BUFFER_SPACE)
+ fatal_fr(r, "reserve");
+ }
+}
+
+#else /* WITH_OPENSSL */
+void
+cleanup_exit(int i)
+{
+ _exit(i);
+}
+
+int
+main(int argc, char **argv)
+{
+ fprintf(stderr, "PKCS#11 code is not enabled\n");
+ return 1;
+}
+#endif /* WITH_OPENSSL */
+#else /* ENABLE_PKCS11 */
+int
+main(int argc, char **argv)
+{
+ extern char *__progname;
+
+ __progname = ssh_get_progname(argv[0]);
+ log_init(__progname, SYSLOG_LEVEL_ERROR, SYSLOG_FACILITY_AUTH, 0);
+ fatal("PKCS#11 support disabled at compile time");
+}
+#endif /* ENABLE_PKCS11 */
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