upstream: actually commit the ssh-sk-helper client code; ok markus
OpenBSD-Commit-ID: fd2ea776a5bbbf4d452989d3c3054cf25a5e0589
This commit is contained in:
djm@openbsd.org
Damien Miller
parent
611073fb40
commit
d214347667
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@ -0,0 +1,323 @@
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/* $OpenBSD: ssh-sk-client.c,v 1.1 2019/12/13 20:16:56 djm Exp $ */
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/*
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* Copyright (c) 2019 Google LLC
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <sys/wait.h>
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#include <errno.h>
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#include <signal.h>
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#include <stdarg.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include "log.h"
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#include "ssherr.h"
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#include "sshbuf.h"
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#include "sshkey.h"
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#include "msg.h"
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#include "digest.h"
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#include "pathnames.h"
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#include "ssh-sk.h"
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/* #define DEBUG_SK 1 */
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static int
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start_helper(int *fdp, pid_t *pidp, void (**osigchldp)(int))
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{
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void (*osigchld)(int);
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int oerrno, pair[2], r = SSH_ERR_INTERNAL_ERROR;
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pid_t pid;
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char *helper, *verbosity = NULL;
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*fdp = -1;
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*pidp = 0;
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*osigchldp = SIG_DFL;
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helper = getenv("SSH_SK_HELPER");
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if (helper == NULL || strlen(helper) == 0)
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helper = _PATH_SSH_SK_HELPER;
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#ifdef DEBUG_SK
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verbosity = "-vvv";
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#endif
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/* Start helper */
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if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1) {
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error("socketpair: %s", strerror(errno));
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return SSH_ERR_SYSTEM_ERROR;
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}
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osigchld = signal(SIGCHLD, SIG_DFL);
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if ((pid = fork()) == -1) {
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oerrno = errno;
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error("fork: %s", strerror(errno));
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close(pair[0]);
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close(pair[1]);
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signal(SIGCHLD, osigchld);
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errno = oerrno;
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return SSH_ERR_SYSTEM_ERROR;
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}
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if (pid == 0) {
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if ((dup2(pair[1], STDIN_FILENO) == -1) ||
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(dup2(pair[1], STDOUT_FILENO) == -1)) {
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error("%s: dup2: %s", __func__, ssh_err(r));
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_exit(1);
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}
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close(pair[0]);
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close(pair[1]);
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closefrom(STDERR_FILENO + 1);
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debug("%s: starting %s %s", __func__, helper,
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verbosity == NULL ? "" : verbosity);
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execlp(helper, helper, verbosity, (char *)NULL);
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error("%s: execlp: %s", __func__, strerror(errno));
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_exit(1);
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}
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close(pair[1]);
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/* success */
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debug3("%s: started pid=%ld", __func__, (long)pid);
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*fdp = pair[0];
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*pidp = pid;
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*osigchldp = osigchld;
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return 0;
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}
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static int
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reap_helper(pid_t pid)
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{
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int status, oerrno;
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debug3("%s: pid=%ld", __func__, (long)pid);
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errno = 0;
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while (waitpid(pid, &status, 0) == -1) {
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if (errno == EINTR) {
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errno = 0;
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continue;
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}
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oerrno = errno;
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error("%s: waitpid: %s", __func__, strerror(errno));
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errno = oerrno;
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return SSH_ERR_SYSTEM_ERROR;
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}
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if (!WIFEXITED(status)) {
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error("%s: helper exited abnormally", __func__);
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return SSH_ERR_AGENT_FAILURE;
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} else if (WEXITSTATUS(status) != 0) {
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error("%s: helper exited with non-zero exit status", __func__);
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return SSH_ERR_AGENT_FAILURE;
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}
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return 0;
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}
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static int
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client_converse(struct sshbuf *req, struct sshbuf **respp)
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{
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int oerrno, fd, r2, r = SSH_ERR_INTERNAL_ERROR;
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pid_t pid;
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u_char version;
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void (*osigchld)(int);
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struct sshbuf *resp = NULL;
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*respp = NULL;
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if ((r = start_helper(&fd, &pid, &osigchld)) != 0)
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return r;
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if ((resp = sshbuf_new()) == NULL) {
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r = SSH_ERR_ALLOC_FAIL;
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goto out;
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}
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if ((r = ssh_msg_send(fd, SSH_SK_HELPER_VERSION, req)) != 0) {
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error("%s: send: %s", __func__, ssh_err(r));
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goto out;
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}
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if ((r = ssh_msg_recv(fd, resp)) != 0) {
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error("%s: receive: %s", __func__, ssh_err(r));
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goto out;
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}
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if ((r = sshbuf_get_u8(resp, &version)) != 0) {
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error("%s: parse version: %s", __func__, ssh_err(r));
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goto out;
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}
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if (version != SSH_SK_HELPER_VERSION) {
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error("%s: unsupported version: got %u, expected %u",
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__func__, version, SSH_SK_HELPER_VERSION);
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r = SSH_ERR_INVALID_FORMAT;
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goto out;
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}
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/* success */
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r = 0;
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out:
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oerrno = errno;
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close(fd);
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if ((r2 = reap_helper(pid)) != 0) {
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if (r == 0) {
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r = r2;
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oerrno = errno;
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}
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}
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if (r == 0) {
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*respp = resp;
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resp = NULL;
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}
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sshbuf_free(resp);
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signal(SIGCHLD, osigchld);
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errno = oerrno;
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return r;
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}
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int
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sshsk_sign(const char *provider, struct sshkey *key,
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u_char **sigp, size_t *lenp, const u_char *data, size_t datalen,
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u_int compat)
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{
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int oerrno, r = SSH_ERR_INTERNAL_ERROR;
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char *fp = NULL;
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struct sshbuf *kbuf = NULL, *req = NULL, *resp = NULL;
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*sigp = NULL;
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*lenp = 0;
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if ((kbuf = sshbuf_new()) == NULL ||
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(req = sshbuf_new()) == NULL) {
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r = SSH_ERR_ALLOC_FAIL;
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goto out;
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}
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if ((r = sshkey_private_serialize(key, kbuf)) != 0) {
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error("%s: serialize private key: %s", __func__, ssh_err(r));
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goto out;
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}
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if ((r = sshbuf_put_u32(req, SSH_SK_HELPER_SIGN)) != 0 ||
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(r = sshbuf_put_stringb(req, kbuf)) != 0 ||
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(r = sshbuf_put_cstring(req, provider)) != 0 ||
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(r = sshbuf_put_string(req, data, datalen)) != 0 ||
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(r = sshbuf_put_cstring(req, NULL)) != 0 || /* alg */
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(r = sshbuf_put_u32(req, compat)) != 0) {
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error("%s: compose: %s", __func__, ssh_err(r));
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goto out;
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}
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if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT,
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SSH_FP_DEFAULT)) == NULL) {
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error("%s: sshkey_fingerprint failed", __func__);
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r = SSH_ERR_ALLOC_FAIL;
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goto out;
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}
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if ((r = client_converse(req, &resp)) != 0)
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goto out;
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if ((r = sshbuf_get_string(resp, sigp, lenp)) != 0) {
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error("%s: parse signature: %s", __func__, ssh_err(r));
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r = SSH_ERR_INVALID_FORMAT;
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goto out;
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}
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if (sshbuf_len(resp) != 0) {
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error("%s: trailing data in response", __func__);
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r = SSH_ERR_INVALID_FORMAT;
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goto out;
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}
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/* success */
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r = 0;
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out:
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oerrno = errno;
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if (r != 0) {
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freezero(*sigp, *lenp);
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*sigp = NULL;
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*lenp = 0;
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}
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sshbuf_free(kbuf);
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sshbuf_free(req);
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sshbuf_free(resp);
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errno = oerrno;
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return r;
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}
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int
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sshsk_enroll(int type, const char *provider_path, const char *application,
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uint8_t flags, struct sshbuf *challenge_buf, struct sshkey **keyp,
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struct sshbuf *attest)
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{
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int oerrno, r = SSH_ERR_INTERNAL_ERROR;
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struct sshbuf *kbuf = NULL, *abuf = NULL, *req = NULL, *resp = NULL;
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struct sshkey *key = NULL;
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*keyp = NULL;
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if (attest != NULL)
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sshbuf_reset(attest);
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if (type < 0)
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return SSH_ERR_INVALID_ARGUMENT;
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if ((abuf = sshbuf_new()) == NULL ||
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(kbuf = sshbuf_new()) == NULL ||
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(req = sshbuf_new()) == NULL) {
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r = SSH_ERR_ALLOC_FAIL;
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goto out;
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}
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if ((r = sshbuf_put_u32(req, SSH_SK_HELPER_ENROLL)) != 0 ||
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(r = sshbuf_put_u32(req, (u_int)type)) != 0 ||
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(r = sshbuf_put_cstring(req, provider_path)) != 0 ||
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(r = sshbuf_put_cstring(req, application)) != 0 ||
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(r = sshbuf_put_u8(req, flags)) != 0 ||
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(r = sshbuf_put_stringb(req, challenge_buf)) != 0) {
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error("%s: compose: %s", __func__, ssh_err(r));
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goto out;
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}
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if ((r = client_converse(req, &resp)) != 0)
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goto out;
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if ((r = sshbuf_get_stringb(resp, kbuf)) != 0 ||
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(r = sshbuf_get_stringb(resp, abuf)) != 0) {
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error("%s: parse signature: %s", __func__, ssh_err(r));
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r = SSH_ERR_INVALID_FORMAT;
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goto out;
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}
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if (sshbuf_len(resp) != 0) {
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error("%s: trailing data in response", __func__);
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r = SSH_ERR_INVALID_FORMAT;
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goto out;
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}
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if ((r = sshkey_private_deserialize(kbuf, &key)) != 0) {
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error("Unable to parse private key: %s", ssh_err(r));
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goto out;
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}
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if (attest != NULL && (r = sshbuf_putb(attest, abuf)) != 0) {
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error("%s: buffer error: %s", __func__, ssh_err(r));
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goto out;
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}
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/* success */
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r = 0;
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*keyp = key;
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key = NULL;
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out:
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oerrno = errno;
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sshkey_free(key);
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sshbuf_free(kbuf);
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sshbuf_free(abuf);
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sshbuf_free(req);
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sshbuf_free(resp);
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errno = oerrno;
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return r;
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}
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