- 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
`

1 files changed, 229 insertions, 0 deletions

diff --git a/ssh-pkcs11-client.c b/ssh-pkcs11-client.c
new file mode 100644
index 000000000..6ffdd9364
--- /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);
+}