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Diffstat (limited to 'ssh-agent.c')
-rw-r--r--ssh-agent.c218
1 files changed, 199 insertions, 19 deletions
diff --git a/ssh-agent.c b/ssh-agent.c
index e500591a..6bf9536f 100644
--- a/ssh-agent.c
+++ b/ssh-agent.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-agent.c,v 1.237 2019/06/28 13:35:04 deraadt Exp $ */
+/* $OpenBSD: ssh-agent.c,v 1.238 2019/10/31 21:22:01 djm Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -41,6 +41,7 @@
#include <sys/resource.h>
#include <sys/stat.h>
#include <sys/socket.h>
+#include <sys/wait.h>
#ifdef HAVE_SYS_TIME_H
# include <sys/time.h>
#endif
@@ -85,13 +86,13 @@
#include "digest.h"
#include "ssherr.h"
#include "match.h"
-
-#ifdef ENABLE_PKCS11
+#include "msg.h"
+#include "pathnames.h"
#include "ssh-pkcs11.h"
-#endif
+#include "ssh-sk.h"
-#ifndef DEFAULT_PKCS11_WHITELIST
-# define DEFAULT_PKCS11_WHITELIST "/usr/lib*/*,/usr/local/lib*/*"
+#ifndef DEFAULT_PROVIDER_WHITELIST
+# define DEFAULT_PROVIDER_WHITELIST "/usr/lib*/*,/usr/local/lib*/*"
#endif
/* Maximum accepted message length */
@@ -123,6 +124,7 @@ typedef struct identity {
char *provider;
time_t death;
u_int confirm;
+ char *sk_provider;
} Identity;
struct idtable {
@@ -146,8 +148,8 @@ pid_t cleanup_pid = 0;
char socket_name[PATH_MAX];
char socket_dir[PATH_MAX];
-/* PKCS#11 path whitelist */
-static char *pkcs11_whitelist;
+/* PKCS#11/Security key path whitelist */
+static char *provider_whitelist;
/* locking */
#define LOCK_SIZE 32
@@ -189,6 +191,7 @@ free_identity(Identity *id)
sshkey_free(id->key);
free(id->provider);
free(id->comment);
+ free(id->sk_provider);
free(id);
}
@@ -278,6 +281,121 @@ agent_decode_alg(struct sshkey *key, u_int flags)
return NULL;
}
+static int
+provider_sign(const char *provider, struct sshkey *key,
+ u_char **sigp, size_t *lenp,
+ const u_char *data, size_t datalen,
+ const char *alg, u_int compat)
+{
+ int status, pair[2], r = SSH_ERR_INTERNAL_ERROR;
+ pid_t pid;
+ char *helper, *verbosity = NULL;
+ struct sshbuf *kbuf, *req, *resp;
+ u_char version;
+
+ debug3("%s: start for provider %s", __func__, provider);
+
+ *sigp = NULL;
+ *lenp = 0;
+
+ helper = getenv("SSH_SK_HELPER");
+ if (helper == NULL || strlen(helper) == 0)
+ helper = _PATH_SSH_SK_HELPER;
+ if (log_level_get() >= SYSLOG_LEVEL_DEBUG1)
+ verbosity = "-vvv";
+
+ /* Start helper */
+ if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1) {
+ error("socketpair: %s", strerror(errno));
+ return SSH_ERR_SYSTEM_ERROR;
+ }
+ if ((pid = fork()) == -1) {
+ error("fork: %s", strerror(errno));
+ close(pair[0]);
+ close(pair[1]);
+ return SSH_ERR_SYSTEM_ERROR;
+ }
+ if (pid == 0) {
+ if ((dup2(pair[1], STDIN_FILENO) == -1) ||
+ (dup2(pair[1], STDOUT_FILENO) == -1))
+ fatal("%s: dup2: %s", __func__, ssh_err(r));
+ close(pair[0]);
+ close(pair[1]);
+ closefrom(STDERR_FILENO + 1);
+ debug("%s: starting %s %s", __func__, helper,
+ verbosity == NULL ? "" : verbosity);
+ execlp(helper, helper, verbosity, (char *)NULL);
+ fatal("%s: execlp: %s", __func__, strerror(errno));
+ }
+ close(pair[1]);
+
+ if ((kbuf = sshbuf_new()) == NULL ||
+ (req = sshbuf_new()) == NULL ||
+ (resp = sshbuf_new()) == NULL)
+ fatal("%s: sshbuf_new failed", __func__);
+
+ if ((r = sshkey_private_serialize(key, kbuf)) != 0 ||
+ (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_u32(req, compat)) != 0)
+ fatal("%s: compose: %s", __func__, ssh_err(r));
+ if ((r = ssh_msg_send(pair[0], SSH_SK_HELPER_VERSION, req)) != 0) {
+ error("%s: send: %s", __func__, ssh_err(r));
+ goto out;
+ }
+ if ((r = ssh_msg_recv(pair[0], resp)) != 0) {
+ error("%s: receive: %s", __func__, ssh_err(r));
+ goto out;
+ }
+ if ((r = sshbuf_get_u8(resp, &version)) != 0) {
+ error("%s: parse version: %s", __func__, ssh_err(r));
+ goto out;
+ }
+ if (version != SSH_SK_HELPER_VERSION) {
+ error("%s: unsupported version: got %u, expected %u",
+ __func__, version, SSH_SK_HELPER_VERSION);
+ r = SSH_ERR_INVALID_FORMAT;
+ goto out;
+ }
+ if ((r = sshbuf_get_string(resp, sigp, lenp)) != 0) {
+ error("%s: parse signature: %s", __func__, ssh_err(r));
+ r = SSH_ERR_INVALID_FORMAT;
+ goto out;
+ }
+ if (sshbuf_len(resp) != 0) {
+ error("%s: trailing data in response", __func__);
+ r = SSH_ERR_INVALID_FORMAT;
+ goto out;
+ }
+ /* success */
+ r = 0;
+ out:
+ while (waitpid(pid, &status, 0) == -1) {
+ if (errno != EINTR)
+ fatal("%s: waitpid: %s", __func__, ssh_err(r));
+ }
+ if (!WIFEXITED(status)) {
+ error("%s: helper %s exited abnormally", __func__, helper);
+ if (r == 0)
+ r = SSH_ERR_SYSTEM_ERROR;
+ } else if (WEXITSTATUS(status) != 0) {
+ error("%s: helper %s exited with non-zero exit status",
+ __func__, helper);
+ if (r == 0)
+ r = SSH_ERR_SYSTEM_ERROR;
+ }
+ if (r != 0) {
+ freezero(*sigp, *lenp);
+ *sigp = NULL;
+ *lenp = 0;
+ }
+ sshbuf_free(kbuf);
+ sshbuf_free(req);
+ sshbuf_free(resp);
+ return r;
+}
+
/* ssh2 only */
static void
process_sign_request2(SocketEntry *e)
@@ -308,10 +426,19 @@ process_sign_request2(SocketEntry *e)
verbose("%s: user refused key", __func__);
goto send;
}
- if ((r = sshkey_sign(id->key, &signature, &slen,
- data, dlen, agent_decode_alg(key, flags), compat)) != 0) {
- error("%s: sshkey_sign: %s", __func__, ssh_err(r));
- goto send;
+ if (id->sk_provider != NULL) {
+ if ((r = provider_sign(id->sk_provider, id->key, &signature,
+ &slen, data, dlen, agent_decode_alg(key, flags),
+ compat)) != 0) {
+ error("%s: sshkey_sign: %s", __func__, ssh_err(r));
+ goto send;
+ }
+ } else {
+ if ((r = sshkey_sign(id->key, &signature, &slen,
+ data, dlen, agent_decode_alg(key, flags), compat)) != 0) {
+ error("%s: sshkey_sign: %s", __func__, ssh_err(r));
+ goto send;
+ }
}
/* Success */
ok = 0;
@@ -411,7 +538,7 @@ process_add_identity(SocketEntry *e)
Identity *id;
int success = 0, confirm = 0;
u_int seconds, maxsign;
- char *comment = NULL;
+ char *fp, *comment = NULL, *ext_name = NULL, *sk_provider = NULL;
time_t death = 0;
struct sshkey *k = NULL;
u_char ctype;
@@ -456,15 +583,58 @@ process_add_identity(SocketEntry *e)
goto err;
}
break;
+ case SSH_AGENT_CONSTRAIN_EXTENSION:
+ if ((r = sshbuf_get_cstring(e->request,
+ &ext_name, NULL)) != 0) {
+ error("%s: cannot parse extension: %s",
+ __func__, ssh_err(r));
+ goto err;
+ }
+ debug("%s: constraint ext %s", __func__, ext_name);
+ if (strcmp(ext_name, "sk-provider@openssh.com") == 0) {
+ if (sk_provider != NULL) {
+ error("%s already set", ext_name);
+ goto err;
+ }
+ if ((r = sshbuf_get_cstring(e->request,
+ &sk_provider, NULL)) != 0) {
+ error("%s: cannot parse %s: %s",
+ __func__, ext_name, ssh_err(r));
+ goto err;
+ }
+ } else {
+ error("%s: unsupported constraint \"%s\"",
+ __func__, ext_name);
+ goto err;
+ }
+ free(ext_name);
+ break;
default:
error("%s: Unknown constraint %d", __func__, ctype);
err:
+ free(sk_provider);
+ free(ext_name);
sshbuf_reset(e->request);
free(comment);
sshkey_free(k);
goto send;
}
}
+ if (sk_provider != NULL) {
+ if (sshkey_type_plain(k->type) != KEY_ECDSA_SK) {
+ error("Cannot add provider: %s is not a security key",
+ sshkey_type(k));
+ free(sk_provider);
+ goto send;
+ }
+ if (match_pattern_list(sk_provider,
+ provider_whitelist, 0) != 1) {
+ error("Refusing add key: provider %s not whitelisted",
+ sk_provider);
+ free(sk_provider);
+ goto send;
+ }
+ }
success = 1;
if (lifetime && !death)
@@ -478,11 +648,21 @@ process_add_identity(SocketEntry *e)
/* key state might have been updated */
sshkey_free(id->key);
free(id->comment);
+ free(id->sk_provider);
}
id->key = k;
id->comment = comment;
id->death = death;
id->confirm = confirm;
+ id->sk_provider = sk_provider;
+
+ if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT,
+ SSH_FP_DEFAULT)) == NULL)
+ fatal("%s: sshkey_fingerprint failed", __func__);
+ debug("%s: add %s %s \"%.100s\" (life: %u) (confirm: %u) "
+ "(provider: %s)", __func__, sshkey_ssh_name(k), fp, comment,
+ seconds, confirm, sk_provider == NULL ? "none" : sk_provider);
+ free(fp);
send:
send_status(e, success);
}
@@ -600,7 +780,7 @@ process_add_smartcard_key(SocketEntry *e)
provider, strerror(errno));
goto send;
}
- if (match_pattern_list(canonical_provider, pkcs11_whitelist, 0) != 1) {
+ if (match_pattern_list(canonical_provider, provider_whitelist, 0) != 1) {
verbose("refusing PKCS#11 add of \"%.100s\": "
"provider not whitelisted", canonical_provider);
goto send;
@@ -1079,7 +1259,7 @@ usage(void)
{
fprintf(stderr,
"usage: ssh-agent [-c | -s] [-Dd] [-a bind_address] [-E fingerprint_hash]\n"
- " [-P pkcs11_whitelist] [-t life] [command [arg ...]]\n"
+ " [-P provider_whitelist] [-t life] [command [arg ...]]\n"
" ssh-agent [-c | -s] -k\n");
exit(1);
}
@@ -1137,9 +1317,9 @@ main(int ac, char **av)
k_flag++;
break;
case 'P':
- if (pkcs11_whitelist != NULL)
+ if (provider_whitelist != NULL)
fatal("-P option already specified");
- pkcs11_whitelist = xstrdup(optarg);
+ provider_whitelist = xstrdup(optarg);
break;
case 's':
if (c_flag)
@@ -1175,8 +1355,8 @@ main(int ac, char **av)
if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag))
usage();
- if (pkcs11_whitelist == NULL)
- pkcs11_whitelist = xstrdup(DEFAULT_PKCS11_WHITELIST);
+ if (provider_whitelist == NULL)
+ provider_whitelist = xstrdup(DEFAULT_PROVIDER_WHITELIST);
if (ac == 0 && !c_flag && !s_flag) {
shell = getenv("SHELL");
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