- markus@cvs.openbsd.org 2010/02/08 10:50:20
[pathnames.h readconf.c readconf.h scp.1 sftp.1 ssh-add.1 ssh-add.c]
[ssh-agent.c ssh-keygen.1 ssh-keygen.c ssh.1 ssh.c ssh_config.5]
replace our obsolete smartcard code with PKCS#11.
ftp://ftp.rsasecurity.com/pub/pkcs/pkcs-11/v2-20/pkcs-11v2-20.pdf
ssh(1) and ssh-keygen(1) use dlopen(3) directly to talk to a PKCS#11
provider (shared library) while ssh-agent(1) delegates PKCS#11 to
a forked a ssh-pkcs11-helper process.
PKCS#11 is currently a compile time option.
feedback and ok djm@; inspired by patches from Alon Bar-Lev
`
diff --git a/ssh-pkcs11-client.c b/ssh-pkcs11-client.c
new file mode 100644
index 0000000..6ffdd93
--- /dev/null
+++ b/ssh-pkcs11-client.c
@@ -0,0 +1,229 @@
+/*
+ * 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 <sys/types.h>
+#include <sys/time.h>
+#include <sys/socket.h>
+
+#include <stdarg.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+
+#include "pathnames.h"
+#include "xmalloc.h"
+#include "buffer.h"
+#include "log.h"
+#include "misc.h"
+#include "key.h"
+#include "authfd.h"
+#include "atomicio.h"
+#include "ssh-pkcs11.h"
+
+/* borrows code from sftp-server and ssh-agent */
+
+int fd = -1;
+pid_t pid = -1;
+
+static void
+send_msg(Buffer *m)
+{
+ u_char buf[4];
+ int mlen = buffer_len(m);
+
+ put_u32(buf, mlen);
+ if (atomicio(vwrite, fd, buf, 4) != 4 ||
+ atomicio(vwrite, fd, buffer_ptr(m),
+ buffer_len(m)) != buffer_len(m))
+ error("write to helper failed");
+ buffer_consume(m, mlen);
+}
+
+static int
+recv_msg(Buffer *m)
+{
+ u_int l, len;
+ u_char buf[1024];
+
+ if ((len = atomicio(read, fd, buf, 4)) != 4) {
+ error("read from helper failed: %u", len);
+ return (0); /* XXX */
+ }
+ len = get_u32(buf);
+ if (len > 256 * 1024)
+ fatal("response too long: %u", len);
+ /* read len bytes into m */
+ buffer_clear(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 */
+ }
+ buffer_append(m, buf, l);
+ len -= l;
+ }
+ return (buffer_get_char(m));
+}
+
+int
+pkcs11_init(int interactive)
+{
+ return (0);
+}
+
+void
+pkcs11_terminate(void)
+{
+ close(fd);
+}
+
+static int
+pkcs11_rsa_private_encrypt(int flen, const u_char *from, u_char *to, RSA *rsa,
+ int padding)
+{
+ Key key;
+ u_char *blob, *signature = NULL;
+ u_int blen, slen = 0;
+ int ret = -1;
+ Buffer msg;
+
+ if (padding != RSA_PKCS1_PADDING)
+ return (-1);
+ key.type = KEY_RSA;
+ key.rsa = rsa;
+ if (key_to_blob(&key, &blob, &blen) == 0)
+ return -1;
+ buffer_init(&msg);
+ buffer_put_char(&msg, SSH2_AGENTC_SIGN_REQUEST);
+ buffer_put_string(&msg, blob, blen);
+ buffer_put_string(&msg, from, flen);
+ buffer_put_int(&msg, 0);
+ xfree(blob);
+ send_msg(&msg);
+
+ if (recv_msg(&msg) == SSH2_AGENT_SIGN_RESPONSE) {
+ signature = buffer_get_string(&msg, &slen);
+ if (slen <= (u_int)RSA_size(rsa)) {
+ memcpy(to, signature, slen);
+ ret = slen;
+ }
+ xfree(signature);
+ }
+ return (ret);
+}
+
+/* redirect the private key encrypt operation to the ssh-pkcs11-helper */
+static int
+wrap_key(RSA *rsa)
+{
+ static RSA_METHOD helper_rsa;
+
+ memcpy(&helper_rsa, RSA_get_default_method(), sizeof(helper_rsa));
+ helper_rsa.name = "ssh-pkcs11-helper";
+ helper_rsa.rsa_priv_enc = pkcs11_rsa_private_encrypt;
+ RSA_set_method(rsa, &helper_rsa);
+ return (0);
+}
+
+static int
+pkcs11_start_helper(void)
+{
+ int pair[2];
+
+ 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]);
+ execlp(_PATH_SSH_PKCS11_HELPER, _PATH_SSH_PKCS11_HELPER,
+ (char *) 0);
+ fprintf(stderr, "exec: %s: %s\n", _PATH_SSH_PKCS11_HELPER,
+ strerror(errno));
+ _exit(1);
+ }
+ close(pair[1]);
+ fd = pair[0];
+ return (0);
+}
+
+int
+pkcs11_add_provider(char *name, char *pin, Key ***keysp)
+{
+ Key *k;
+ int i, nkeys;
+ u_char *blob;
+ u_int blen;
+ Buffer msg;
+
+ if (fd < 0 && pkcs11_start_helper() < 0)
+ return (-1);
+
+ buffer_init(&msg);
+ buffer_put_char(&msg, SSH_AGENTC_ADD_SMARTCARD_KEY);
+ buffer_put_cstring(&msg, name);
+ buffer_put_cstring(&msg, pin);
+ send_msg(&msg);
+ buffer_clear(&msg);
+
+ if (recv_msg(&msg) == SSH2_AGENT_IDENTITIES_ANSWER) {
+ nkeys = buffer_get_int(&msg);
+ *keysp = xcalloc(nkeys, sizeof(Key *));
+ for (i = 0; i < nkeys; i++) {
+ blob = buffer_get_string(&msg, &blen);
+ xfree(buffer_get_string(&msg, NULL));
+ k = key_from_blob(blob, blen);
+ wrap_key(k->rsa);
+ (*keysp)[i] = k;
+ xfree(blob);
+ }
+ } else {
+ nkeys = -1;
+ }
+ buffer_free(&msg);
+ return (nkeys);
+}
+
+int
+pkcs11_del_provider(char *name)
+{
+ int ret = -1;
+ Buffer msg;
+
+ buffer_init(&msg);
+ buffer_put_char(&msg, SSH_AGENTC_REMOVE_SMARTCARD_KEY);
+ buffer_put_cstring(&msg, name);
+ buffer_put_cstring(&msg, "");
+ send_msg(&msg);
+ buffer_clear(&msg);
+
+ if (recv_msg(&msg) == SSH_AGENT_SUCCESS)
+ ret = 0;
+ buffer_free(&msg);
+ return (ret);
+}