- 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, 349 insertions, 0 deletions

diff --git a/ssh-pkcs11-helper.c b/ssh-pkcs11-helper.c
new file mode 100644
index 000000000..f9962709b
--- /dev/null
+++ b/ssh-pkcs11-helper.c
@@ -0,0 +1,349 @@
+/*
+ * 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/queue.h>
+#include <sys/types.h>
+#include <sys/time.h>
+
+#include <stdarg.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+
+#include "xmalloc.h"
+#include "buffer.h"
+#include "log.h"
+#include "misc.h"
+#include "key.h"
+#include "authfd.h"
+#include "ssh-pkcs11.h"
+
+/* borrows code from sftp-server and ssh-agent */
+
+struct pkcs11_keyinfo {
+        Key             *key;
+        char            *providername;
+        TAILQ_ENTRY(pkcs11_keyinfo) next;
+};
+
+TAILQ_HEAD(, pkcs11_keyinfo) pkcs11_keylist;
+
+#define MAX_MSG_LENGTH          10240 /*XXX*/
+
+/* helper */
+#define get_int()                       buffer_get_int(&iqueue);
+#define get_string(lenp)                buffer_get_string(&iqueue, lenp);
+
+/* input and output queue */
+Buffer iqueue;
+Buffer oqueue;
+
+static void
+add_key(Key *k, char *name)
+{
+        struct pkcs11_keyinfo *ki;
+
+        ki = xcalloc(1, sizeof(*ki));
+        ki->providername = xstrdup(name);
+        ki->key = k;
+        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);
+                        xfree(ki->providername);
+                        key_free(ki->key);
+                        free(ki);
+                }
+        }
+}
+
+/* lookup matching 'private' key */
+static Key *
+lookup_key(Key *k)
+{
+        struct pkcs11_keyinfo *ki;
+
+        TAILQ_FOREACH(ki, &pkcs11_keylist, next) {
+                debug("check %p %s", ki, ki->providername);
+                if (key_equal(k, ki->key))
+                        return (ki->key);
+        }
+        return (NULL);
+}
+
+static void
+send_msg(Buffer *m)
+{
+        int mlen = buffer_len(m);
+
+        buffer_put_int(&oqueue, mlen);
+        buffer_append(&oqueue, buffer_ptr(m), mlen);
+        buffer_consume(m, mlen);
+}
+
+static void
+process_add(void)
+{
+        char *name, *pin;
+        Key **keys;
+        int i, nkeys;
+        u_char *blob;
+        u_int blen;
+        Buffer msg;
+
+        buffer_init(&msg);
+        name = get_string(NULL);
+        pin = get_string(NULL);
+        if ((nkeys = pkcs11_add_provider(name, pin, &keys)) > 0) {
+                buffer_put_char(&msg, SSH2_AGENT_IDENTITIES_ANSWER);
+                buffer_put_int(&msg, nkeys);
+                for (i = 0; i < nkeys; i++) {
+                        key_to_blob(keys[i], &blob, &blen);
+                        buffer_put_string(&msg, blob, blen);
+                        buffer_put_cstring(&msg, name);
+                        xfree(blob);
+                        add_key(keys[i], name);
+                }
+                xfree(keys);
+        } else {
+                buffer_put_char(&msg, SSH_AGENT_FAILURE);
+        }
+        xfree(pin);
+        xfree(name);
+        send_msg(&msg);
+        buffer_free(&msg);
+}
+
+static void
+process_del(void)
+{
+        char *name, *pin;
+        Buffer msg;
+
+        buffer_init(&msg);
+        name = get_string(NULL);
+        pin = get_string(NULL);
+        del_keys_by_name(name);
+        if (pkcs11_del_provider(name) == 0)
+                 buffer_put_char(&msg, SSH_AGENT_SUCCESS);
+        else
+                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
+        xfree(pin);
+        xfree(name);
+        send_msg(&msg);
+        buffer_free(&msg);
+}
+
+static void
+process_sign(void)
+{
+        u_char *blob, *data, *signature = NULL;
+        u_int blen, dlen, slen = 0;
+        int ok = -1, flags, ret;
+        Key *key, *found;
+        Buffer msg;
+
+        blob = get_string(&blen);
+        data = get_string(&dlen);
+        flags = get_int(); /* XXX ignore */
+
+        if ((key = key_from_blob(blob, blen)) != NULL) {
+                if ((found = lookup_key(key)) != NULL) {
+                        slen = RSA_size(key->rsa);
+                        signature = xmalloc(slen);
+                        if ((ret = RSA_private_encrypt(dlen, data, signature,
+                            found->rsa, RSA_PKCS1_PADDING)) != -1) {
+                                slen = ret;
+                                ok = 0;
+                        }
+                }
+                key_free(key);
+        }
+        buffer_init(&msg);
+        if (ok == 0) {
+                buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
+                buffer_put_string(&msg, signature, slen);
+        } else {
+                buffer_put_char(&msg, SSH_AGENT_FAILURE);
+        }
+        xfree(data);
+        xfree(blob);
+        if (signature != NULL)
+                xfree(signature);
+        send_msg(&msg);
+        buffer_free(&msg);
+}
+
+static void
+process(void)
+{
+        u_int msg_len;
+        u_int buf_len;
+        u_int consumed;
+        u_int type;
+        u_char *cp;
+
+        buf_len = buffer_len(&iqueue);
+        if (buf_len < 5)
+                return;         /* Incomplete message. */
+        cp = buffer_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;
+        buffer_consume(&iqueue, 4);
+        buf_len -= 4;
+        type = buffer_get_char(&iqueue);
+        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 < buffer_len(&iqueue)) {
+                error("iqueue grew unexpectedly");
+                cleanup_exit(255);
+        }
+        consumed = buf_len - buffer_len(&iqueue);
+        if (msg_len < consumed) {
+                error("msg_len %d < consumed %d", msg_len, consumed);
+                cleanup_exit(255);
+        }
+        if (msg_len > consumed)
+                buffer_consume(&iqueue, msg_len - consumed);
+}
+
+void
+cleanup_exit(int i)
+{
+        /* XXX */
+        _exit(i);
+}
+
+int
+main(int argc, char **argv)
+{
+        fd_set *rset, *wset;
+        int in, out, max, log_stderr = 0;
+        ssize_t len, olen, set_size;
+        SyslogFacility log_facility = SYSLOG_FACILITY_AUTH;
+        LogLevel log_level = SYSLOG_LEVEL_ERROR;
+        char buf[4*4096];
+
+        TAILQ_INIT(&pkcs11_keylist);
+        pkcs11_init(0);
+
+        extern char *optarg;
+        extern char *__progname;
+
+        log_init(__progname, log_level, log_facility, log_stderr);
+
+        in = STDIN_FILENO;
+        out = STDOUT_FILENO;
+
+        max = 0;
+        if (in > max)
+                max = in;
+        if (out > max)
+                max = out;
+
+        buffer_init(&iqueue);
+        buffer_init(&oqueue);
+
+        set_size = howmany(max + 1, NFDBITS) * sizeof(fd_mask);
+        rset = (fd_set *)xmalloc(set_size);
+        wset = (fd_set *)xmalloc(set_size);
+
+        for (;;) {
+                memset(rset, 0, set_size);
+                memset(wset, 0, set_size);
+
+                /*
+                 * 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 (buffer_check_alloc(&iqueue, sizeof(buf)) &&
+                    buffer_check_alloc(&oqueue, MAX_MSG_LENGTH))
+                        FD_SET(in, rset);
+
+                olen = buffer_len(&oqueue);
+                if (olen > 0)
+                        FD_SET(out, wset);
+
+                if (select(max+1, rset, wset, NULL, NULL) < 0) {
+                        if (errno == EINTR)
+                                continue;
+                        error("select: %s", strerror(errno));
+                        cleanup_exit(2);
+                }
+
+                /* copy stdin to iqueue */
+                if (FD_ISSET(in, rset)) {
+                        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 {
+                                buffer_append(&iqueue, buf, len);
+                        }
+                }
+                /* send oqueue to stdout */
+                if (FD_ISSET(out, wset)) {
+                        len = write(out, buffer_ptr(&oqueue), olen);
+                        if (len < 0) {
+                                error("write: %s", strerror(errno));
+                                cleanup_exit(1);
+                        } else {
+                                buffer_consume(&oqueue, len);
+                        }
+                }
+
+                /*
+                 * 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 (buffer_check_alloc(&oqueue, MAX_MSG_LENGTH))
+                        process();
+        }
+}