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-rw-r--r--ssh-sk-client.c480
1 files changed, 480 insertions, 0 deletions
diff --git a/ssh-sk-client.c b/ssh-sk-client.c
new file mode 100644
index 0000000..321fe53
--- /dev/null
+++ b/ssh-sk-client.c
@@ -0,0 +1,480 @@
+/* $OpenBSD: ssh-sk-client.c,v 1.12 2022/01/14 03:34:00 djm Exp $ */
+/*
+ * Copyright (c) 2019 Google LLC
+ *
+ * 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>
+#include <sys/socket.h>
+#include <sys/wait.h>
+
+#include <fcntl.h>
+#include <limits.h>
+#include <errno.h>
+#include <signal.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "log.h"
+#include "ssherr.h"
+#include "sshbuf.h"
+#include "sshkey.h"
+#include "msg.h"
+#include "digest.h"
+#include "pathnames.h"
+#include "ssh-sk.h"
+#include "misc.h"
+
+/* #define DEBUG_SK 1 */
+
+static int
+start_helper(int *fdp, pid_t *pidp, void (**osigchldp)(int))
+{
+ void (*osigchld)(int);
+ int oerrno, pair[2];
+ pid_t pid;
+ char *helper, *verbosity = NULL;
+
+ *fdp = -1;
+ *pidp = 0;
+ *osigchldp = SIG_DFL;
+
+ helper = getenv("SSH_SK_HELPER");
+ if (helper == NULL || strlen(helper) == 0)
+ helper = _PATH_SSH_SK_HELPER;
+ if (access(helper, X_OK) != 0) {
+ oerrno = errno;
+ error_f("helper \"%s\" unusable: %s", helper, strerror(errno));
+ errno = oerrno;
+ return SSH_ERR_SYSTEM_ERROR;
+ }
+#ifdef DEBUG_SK
+ verbosity = "-vvv";
+#endif
+
+ /* Start helper */
+ if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1) {
+ error("socketpair: %s", strerror(errno));
+ return SSH_ERR_SYSTEM_ERROR;
+ }
+ osigchld = ssh_signal(SIGCHLD, SIG_DFL);
+ if ((pid = fork()) == -1) {
+ oerrno = errno;
+ error("fork: %s", strerror(errno));
+ close(pair[0]);
+ close(pair[1]);
+ ssh_signal(SIGCHLD, osigchld);
+ errno = oerrno;
+ return SSH_ERR_SYSTEM_ERROR;
+ }
+ if (pid == 0) {
+ if ((dup2(pair[1], STDIN_FILENO) == -1) ||
+ (dup2(pair[1], STDOUT_FILENO) == -1)) {
+ error_f("dup2: %s", strerror(errno));
+ _exit(1);
+ }
+ close(pair[0]);
+ close(pair[1]);
+ closefrom(STDERR_FILENO + 1);
+ debug_f("starting %s %s", helper,
+ verbosity == NULL ? "" : verbosity);
+ execlp(helper, helper, verbosity, (char *)NULL);
+ error_f("execlp: %s", strerror(errno));
+ _exit(1);
+ }
+ close(pair[1]);
+
+ /* success */
+ debug3_f("started pid=%ld", (long)pid);
+ *fdp = pair[0];
+ *pidp = pid;
+ *osigchldp = osigchld;
+ return 0;
+}
+
+static int
+reap_helper(pid_t pid)
+{
+ int status, oerrno;
+
+ debug3_f("pid=%ld", (long)pid);
+
+ errno = 0;
+ while (waitpid(pid, &status, 0) == -1) {
+ if (errno == EINTR) {
+ errno = 0;
+ continue;
+ }
+ oerrno = errno;
+ error_f("waitpid: %s", strerror(errno));
+ errno = oerrno;
+ return SSH_ERR_SYSTEM_ERROR;
+ }
+ if (!WIFEXITED(status)) {
+ error_f("helper exited abnormally");
+ return SSH_ERR_AGENT_FAILURE;
+ } else if (WEXITSTATUS(status) != 0) {
+ error_f("helper exited with non-zero exit status");
+ return SSH_ERR_AGENT_FAILURE;
+ }
+ return 0;
+}
+
+static int
+client_converse(struct sshbuf *msg, struct sshbuf **respp, u_int type)
+{
+ int oerrno, fd, r2, ll, r = SSH_ERR_INTERNAL_ERROR;
+ u_int rtype, rerr;
+ pid_t pid;
+ u_char version;
+ void (*osigchld)(int);
+ struct sshbuf *req = NULL, *resp = NULL;
+ *respp = NULL;
+
+ if ((r = start_helper(&fd, &pid, &osigchld)) != 0)
+ return r;
+
+ if ((req = sshbuf_new()) == NULL || (resp = sshbuf_new()) == NULL) {
+ r = SSH_ERR_ALLOC_FAIL;
+ goto out;
+ }
+ /* Request preamble: type, log_on_stderr, log_level */
+ ll = log_level_get();
+ if ((r = sshbuf_put_u32(req, type)) != 0 ||
+ (r = sshbuf_put_u8(req, log_is_on_stderr() != 0)) != 0 ||
+ (r = sshbuf_put_u32(req, ll < 0 ? 0 : ll)) != 0 ||
+ (r = sshbuf_putb(req, msg)) != 0) {
+ error_fr(r, "compose");
+ goto out;
+ }
+ if ((r = ssh_msg_send(fd, SSH_SK_HELPER_VERSION, req)) != 0) {
+ error_fr(r, "send");
+ goto out;
+ }
+ if ((r = ssh_msg_recv(fd, resp)) != 0) {
+ error_fr(r, "receive");
+ goto out;
+ }
+ if ((r = sshbuf_get_u8(resp, &version)) != 0) {
+ error_fr(r, "parse version");
+ goto out;
+ }
+ if (version != SSH_SK_HELPER_VERSION) {
+ error_f("unsupported version: got %u, expected %u",
+ version, SSH_SK_HELPER_VERSION);
+ r = SSH_ERR_INVALID_FORMAT;
+ goto out;
+ }
+ if ((r = sshbuf_get_u32(resp, &rtype)) != 0) {
+ error_fr(r, "parse message type");
+ goto out;
+ }
+ if (rtype == SSH_SK_HELPER_ERROR) {
+ if ((r = sshbuf_get_u32(resp, &rerr)) != 0) {
+ error_fr(r, "parse");
+ goto out;
+ }
+ debug_f("helper returned error -%u", rerr);
+ /* OpenSSH error values are negative; encoded as -err on wire */
+ if (rerr == 0 || rerr >= INT_MAX)
+ r = SSH_ERR_INTERNAL_ERROR;
+ else
+ r = -(int)rerr;
+ goto out;
+ } else if (rtype != type) {
+ error_f("helper returned incorrect message type %u, "
+ "expecting %u", rtype, type);
+ r = SSH_ERR_INTERNAL_ERROR;
+ goto out;
+ }
+ /* success */
+ r = 0;
+ out:
+ oerrno = errno;
+ close(fd);
+ if ((r2 = reap_helper(pid)) != 0) {
+ if (r == 0) {
+ r = r2;
+ oerrno = errno;
+ }
+ }
+ if (r == 0) {
+ *respp = resp;
+ resp = NULL;
+ }
+ sshbuf_free(req);
+ sshbuf_free(resp);
+ ssh_signal(SIGCHLD, osigchld);
+ errno = oerrno;
+ return r;
+
+}
+
+int
+sshsk_sign(const char *provider, struct sshkey *key,
+ u_char **sigp, size_t *lenp, const u_char *data, size_t datalen,
+ u_int compat, const char *pin)
+{
+ int oerrno, r = SSH_ERR_INTERNAL_ERROR;
+ struct sshbuf *kbuf = NULL, *req = NULL, *resp = NULL;
+
+ *sigp = NULL;
+ *lenp = 0;
+
+#ifndef ENABLE_SK
+ return SSH_ERR_KEY_TYPE_UNKNOWN;
+#endif
+
+ if ((kbuf = sshbuf_new()) == NULL ||
+ (req = sshbuf_new()) == NULL) {
+ r = SSH_ERR_ALLOC_FAIL;
+ goto out;
+ }
+
+ if ((r = sshkey_private_serialize(key, kbuf)) != 0) {
+ error_fr(r, "encode key");
+ goto out;
+ }
+ if ((r = sshbuf_put_stringb(req, kbuf)) != 0 ||
+ (r = sshbuf_put_cstring(req, provider)) != 0 ||
+ (r = sshbuf_put_string(req, data, datalen)) != 0 ||
+ (r = sshbuf_put_cstring(req, NULL)) != 0 || /* alg */
+ (r = sshbuf_put_u32(req, compat)) != 0 ||
+ (r = sshbuf_put_cstring(req, pin)) != 0) {
+ error_fr(r, "compose");
+ goto out;
+ }
+
+ if ((r = client_converse(req, &resp, SSH_SK_HELPER_SIGN)) != 0)
+ goto out;
+
+ if ((r = sshbuf_get_string(resp, sigp, lenp)) != 0) {
+ error_fr(r, "parse signature");
+ r = SSH_ERR_INVALID_FORMAT;
+ goto out;
+ }
+ if (sshbuf_len(resp) != 0) {
+ error_f("trailing data in response");
+ r = SSH_ERR_INVALID_FORMAT;
+ goto out;
+ }
+ /* success */
+ r = 0;
+ out:
+ oerrno = errno;
+ if (r != 0) {
+ freezero(*sigp, *lenp);
+ *sigp = NULL;
+ *lenp = 0;
+ }
+ sshbuf_free(kbuf);
+ sshbuf_free(req);
+ sshbuf_free(resp);
+ errno = oerrno;
+ return r;
+}
+
+int
+sshsk_enroll(int type, const char *provider_path, const char *device,
+ const char *application, const char *userid, uint8_t flags,
+ const char *pin, struct sshbuf *challenge_buf,
+ struct sshkey **keyp, struct sshbuf *attest)
+{
+ int oerrno, r = SSH_ERR_INTERNAL_ERROR;
+ struct sshbuf *kbuf = NULL, *abuf = NULL, *req = NULL, *resp = NULL;
+ struct sshkey *key = NULL;
+
+ *keyp = NULL;
+ if (attest != NULL)
+ sshbuf_reset(attest);
+
+#ifndef ENABLE_SK
+ return SSH_ERR_KEY_TYPE_UNKNOWN;
+#endif
+
+ if (type < 0)
+ return SSH_ERR_INVALID_ARGUMENT;
+
+ if ((abuf = sshbuf_new()) == NULL ||
+ (kbuf = sshbuf_new()) == NULL ||
+ (req = sshbuf_new()) == NULL) {
+ r = SSH_ERR_ALLOC_FAIL;
+ goto out;
+ }
+
+ if ((r = sshbuf_put_u32(req, (u_int)type)) != 0 ||
+ (r = sshbuf_put_cstring(req, provider_path)) != 0 ||
+ (r = sshbuf_put_cstring(req, device)) != 0 ||
+ (r = sshbuf_put_cstring(req, application)) != 0 ||
+ (r = sshbuf_put_cstring(req, userid)) != 0 ||
+ (r = sshbuf_put_u8(req, flags)) != 0 ||
+ (r = sshbuf_put_cstring(req, pin)) != 0 ||
+ (r = sshbuf_put_stringb(req, challenge_buf)) != 0) {
+ error_fr(r, "compose");
+ goto out;
+ }
+
+ if ((r = client_converse(req, &resp, SSH_SK_HELPER_ENROLL)) != 0)
+ goto out;
+
+ if ((r = sshbuf_get_stringb(resp, kbuf)) != 0 ||
+ (r = sshbuf_get_stringb(resp, abuf)) != 0) {
+ error_fr(r, "parse");
+ r = SSH_ERR_INVALID_FORMAT;
+ goto out;
+ }
+ if (sshbuf_len(resp) != 0) {
+ error_f("trailing data in response");
+ r = SSH_ERR_INVALID_FORMAT;
+ goto out;
+ }
+ if ((r = sshkey_private_deserialize(kbuf, &key)) != 0) {
+ error_fr(r, "encode");
+ goto out;
+ }
+ if (attest != NULL && (r = sshbuf_putb(attest, abuf)) != 0) {
+ error_fr(r, "encode attestation information");
+ goto out;
+ }
+
+ /* success */
+ r = 0;
+ *keyp = key;
+ key = NULL;
+ out:
+ oerrno = errno;
+ sshkey_free(key);
+ sshbuf_free(kbuf);
+ sshbuf_free(abuf);
+ sshbuf_free(req);
+ sshbuf_free(resp);
+ errno = oerrno;
+ return r;
+}
+
+static void
+sshsk_free_resident_key(struct sshsk_resident_key *srk)
+{
+ if (srk == NULL)
+ return;
+ sshkey_free(srk->key);
+ freezero(srk->user_id, srk->user_id_len);
+ free(srk);
+}
+
+
+void
+sshsk_free_resident_keys(struct sshsk_resident_key **srks, size_t nsrks)
+{
+ size_t i;
+
+ if (srks == NULL || nsrks == 0)
+ return;
+
+ for (i = 0; i < nsrks; i++)
+ sshsk_free_resident_key(srks[i]);
+ free(srks);
+}
+
+int
+sshsk_load_resident(const char *provider_path, const char *device,
+ const char *pin, u_int flags, struct sshsk_resident_key ***srksp,
+ size_t *nsrksp)
+{
+ int oerrno, r = SSH_ERR_INTERNAL_ERROR;
+ struct sshbuf *kbuf = NULL, *req = NULL, *resp = NULL;
+ struct sshkey *key = NULL;
+ struct sshsk_resident_key *srk = NULL, **srks = NULL, **tmp;
+ u_char *userid = NULL;
+ size_t userid_len = 0, nsrks = 0;
+
+ *srksp = NULL;
+ *nsrksp = 0;
+
+ if ((kbuf = sshbuf_new()) == NULL ||
+ (req = sshbuf_new()) == NULL) {
+ r = SSH_ERR_ALLOC_FAIL;
+ goto out;
+ }
+
+ if ((r = sshbuf_put_cstring(req, provider_path)) != 0 ||
+ (r = sshbuf_put_cstring(req, device)) != 0 ||
+ (r = sshbuf_put_cstring(req, pin)) != 0 ||
+ (r = sshbuf_put_u32(req, flags)) != 0) {
+ error_fr(r, "compose");
+ goto out;
+ }
+
+ if ((r = client_converse(req, &resp, SSH_SK_HELPER_LOAD_RESIDENT)) != 0)
+ goto out;
+
+ while (sshbuf_len(resp) != 0) {
+ /* key, comment, user_id */
+ if ((r = sshbuf_get_stringb(resp, kbuf)) != 0 ||
+ (r = sshbuf_get_cstring(resp, NULL, NULL)) != 0 ||
+ (r = sshbuf_get_string(resp, &userid, &userid_len)) != 0) {
+ error_fr(r, "parse");
+ r = SSH_ERR_INVALID_FORMAT;
+ goto out;
+ }
+ if ((r = sshkey_private_deserialize(kbuf, &key)) != 0) {
+ error_fr(r, "decode key");
+ goto out;
+ }
+ if ((srk = calloc(1, sizeof(*srk))) == NULL) {
+ error_f("calloc failed");
+ goto out;
+ }
+ srk->key = key;
+ key = NULL;
+ srk->user_id = userid;
+ srk->user_id_len = userid_len;
+ userid = NULL;
+ userid_len = 0;
+ if ((tmp = recallocarray(srks, nsrks, nsrks + 1,
+ sizeof(*srks))) == NULL) {
+ error_f("recallocarray keys failed");
+ goto out;
+ }
+ debug_f("srks[%zu]: %s %s uidlen %zu", nsrks,
+ sshkey_type(srk->key), srk->key->sk_application,
+ srk->user_id_len);
+ srks = tmp;
+ srks[nsrks++] = srk;
+ srk = NULL;
+ }
+
+ /* success */
+ r = 0;
+ *srksp = srks;
+ *nsrksp = nsrks;
+ srks = NULL;
+ nsrks = 0;
+ out:
+ oerrno = errno;
+ sshsk_free_resident_key(srk);
+ sshsk_free_resident_keys(srks, nsrks);
+ freezero(userid, userid_len);
+ sshkey_free(key);
+ sshbuf_free(kbuf);
+ sshbuf_free(req);
+ sshbuf_free(resp);
+ errno = oerrno;
+ return r;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-16 20:15:25 +0000