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-rw-r--r--auth2.c394
1 files changed, 297 insertions, 97 deletions
diff --git a/auth2.c b/auth2.c
index 71779622..91aaf34a 100644
--- a/auth2.c
+++ b/auth2.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: auth2.c,v 1.135 2015/01/19 20:07:45 markus Exp $ */
+/* $OpenBSD: auth2.c,v 1.158 2020/03/06 18:16:21 markus Exp $ */
/*
* Copyright (c) 2000 Markus Friedl. All rights reserved.
*
@@ -30,37 +30,40 @@
#include <sys/uio.h>
#include <fcntl.h>
+#include <limits.h>
#include <pwd.h>
#include <stdarg.h>
#include <string.h>
#include <unistd.h>
+#include <time.h>
+#include "stdlib.h"
#include "atomicio.h"
#include "xmalloc.h"
#include "ssh2.h"
#include "packet.h"
#include "log.h"
-#include "buffer.h"
+#include "sshbuf.h"
#include "misc.h"
#include "servconf.h"
#include "compat.h"
-#include "key.h"
+#include "sshkey.h"
#include "hostfile.h"
#include "auth.h"
#include "dispatch.h"
#include "pathnames.h"
-#include "buffer.h"
-
+#include "ssherr.h"
#ifdef GSSAPI
#include "ssh-gss.h"
#endif
#include "monitor_wrap.h"
+#include "digest.h"
/* import */
extern ServerOptions options;
extern u_char *session_id2;
extern u_int session_id2_len;
-extern Buffer loginmsg;
+extern struct sshbuf *loginmsg;
/* methods */
@@ -87,8 +90,8 @@ Authmethod *authmethods[] = {
/* protocol */
-static int input_service_request(int, u_int32_t, void *);
-static int input_userauth_request(int, u_int32_t, void *);
+static int input_service_request(int, u_int32_t, struct ssh *);
+static int input_userauth_request(int, u_int32_t, struct ssh *);
/* helper */
static Authmethod *authmethod_lookup(Authctxt *, const char *);
@@ -133,30 +136,30 @@ auth2_read_banner(void)
return (banner);
}
-void
-userauth_send_banner(const char *msg)
+static void
+userauth_send_banner(struct ssh *ssh, const char *msg)
{
- if (datafellows & SSH_BUG_BANNER)
- return;
+ int r;
- packet_start(SSH2_MSG_USERAUTH_BANNER);
- packet_put_cstring(msg);
- packet_put_cstring(""); /* language, unused */
- packet_send();
+ if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_BANNER)) != 0 ||
+ (r = sshpkt_put_cstring(ssh, msg)) != 0 ||
+ (r = sshpkt_put_cstring(ssh, "")) != 0 || /* language, unused */
+ (r = sshpkt_send(ssh)) != 0)
+ fatal("%s: %s", __func__, ssh_err(r));
debug("%s: sent", __func__);
}
static void
-userauth_banner(void)
+userauth_banner(struct ssh *ssh)
{
char *banner = NULL;
- if (options.banner == NULL || (datafellows & SSH_BUG_BANNER) != 0)
+ if (options.banner == NULL)
return;
if ((banner = PRIVSEP(auth2_read_banner())) == NULL)
goto done;
- userauth_send_banner(banner);
+ userauth_send_banner(ssh, banner);
done:
free(banner);
@@ -166,22 +169,27 @@ done:
* loop until authctxt->success == TRUE
*/
void
-do_authentication2(Authctxt *authctxt)
+do_authentication2(struct ssh *ssh)
{
- dispatch_init(&dispatch_protocol_error);
- dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
- dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt);
+ Authctxt *authctxt = ssh->authctxt;
+
+ ssh_dispatch_init(ssh, &dispatch_protocol_error);
+ ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_REQUEST, &input_service_request);
+ ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt->success);
+ ssh->authctxt = NULL;
}
/*ARGSUSED*/
static int
-input_service_request(int type, u_int32_t seq, void *ctxt)
+input_service_request(int type, u_int32_t seq, struct ssh *ssh)
{
- Authctxt *authctxt = ctxt;
- u_int len;
- int acceptit = 0;
- char *service = packet_get_cstring(&len);
- packet_check_eom();
+ Authctxt *authctxt = ssh->authctxt;
+ char *service = NULL;
+ int r, acceptit = 0;
+
+ if ((r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 ||
+ (r = sshpkt_get_end(ssh)) != 0)
+ goto out;
if (authctxt == NULL)
fatal("input_service_request: no authctxt");
@@ -190,39 +198,82 @@ input_service_request(int type, u_int32_t seq, void *ctxt)
if (!authctxt->success) {
acceptit = 1;
/* now we can handle user-auth requests */
- dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
+ ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST,
+ &input_userauth_request);
}
}
/* XXX all other service requests are denied */
if (acceptit) {
- packet_start(SSH2_MSG_SERVICE_ACCEPT);
- packet_put_cstring(service);
- packet_send();
- packet_write_wait();
+ if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_ACCEPT)) != 0 ||
+ (r = sshpkt_put_cstring(ssh, service)) != 0 ||
+ (r = sshpkt_send(ssh)) != 0 ||
+ (r = ssh_packet_write_wait(ssh)) != 0)
+ goto out;
} else {
debug("bad service request %s", service);
- packet_disconnect("bad service request %s", service);
+ ssh_packet_disconnect(ssh, "bad service request %s", service);
}
+ r = 0;
+ out:
free(service);
- return 0;
+ return r;
+}
+
+#define MIN_FAIL_DELAY_SECONDS 0.005
+static double
+user_specific_delay(const char *user)
+{
+ char b[512];
+ size_t len = ssh_digest_bytes(SSH_DIGEST_SHA512);
+ u_char *hash = xmalloc(len);
+ double delay;
+
+ (void)snprintf(b, sizeof b, "%llu%s",
+ (unsigned long long)options.timing_secret, user);
+ if (ssh_digest_memory(SSH_DIGEST_SHA512, b, strlen(b), hash, len) != 0)
+ fatal("%s: ssh_digest_memory", __func__);
+ /* 0-4.2 ms of delay */
+ delay = (double)PEEK_U32(hash) / 1000 / 1000 / 1000 / 1000;
+ freezero(hash, len);
+ debug3("%s: user specific delay %0.3lfms", __func__, delay/1000);
+ return MIN_FAIL_DELAY_SECONDS + delay;
+}
+
+static void
+ensure_minimum_time_since(double start, double seconds)
+{
+ struct timespec ts;
+ double elapsed = monotime_double() - start, req = seconds, remain;
+
+ /* if we've already passed the requested time, scale up */
+ while ((remain = seconds - elapsed) < 0.0)
+ seconds *= 2;
+
+ ts.tv_sec = remain;
+ ts.tv_nsec = (remain - ts.tv_sec) * 1000000000;
+ debug3("%s: elapsed %0.3lfms, delaying %0.3lfms (requested %0.3lfms)",
+ __func__, elapsed*1000, remain*1000, req*1000);
+ nanosleep(&ts, NULL);
}
/*ARGSUSED*/
static int
-input_userauth_request(int type, u_int32_t seq, void *ctxt)
+input_userauth_request(int type, u_int32_t seq, struct ssh *ssh)
{
- Authctxt *authctxt = ctxt;
+ Authctxt *authctxt = ssh->authctxt;
Authmethod *m = NULL;
- char *user, *service, *method, *style = NULL;
- int authenticated = 0;
+ char *user = NULL, *service = NULL, *method = NULL, *style = NULL;
+ int r, authenticated = 0;
+ double tstart = monotime_double();
if (authctxt == NULL)
fatal("input_userauth_request: no authctxt");
- user = packet_get_cstring(NULL);
- service = packet_get_cstring(NULL);
- method = packet_get_cstring(NULL);
+ if ((r = sshpkt_get_cstring(ssh, &user, NULL)) != 0 ||
+ (r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 ||
+ (r = sshpkt_get_cstring(ssh, &method, NULL)) != 0)
+ goto out;
debug("userauth-request for user %s service %s method %s", user, service, method);
debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
@@ -231,46 +282,51 @@ input_userauth_request(int type, u_int32_t seq, void *ctxt)
if (authctxt->attempt++ == 0) {
/* setup auth context */
- authctxt->pw = PRIVSEP(getpwnamallow(user));
+ authctxt->pw = PRIVSEP(getpwnamallow(ssh, user));
authctxt->user = xstrdup(user);
if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
authctxt->valid = 1;
- debug2("input_userauth_request: setting up authctxt for %s", user);
+ debug2("%s: setting up authctxt for %s",
+ __func__, user);
} else {
- logit("input_userauth_request: invalid user %s", user);
+ /* Invalid user, fake password information */
authctxt->pw = fakepw();
#ifdef SSH_AUDIT_EVENTS
- PRIVSEP(audit_event(SSH_INVALID_USER));
+ PRIVSEP(audit_event(ssh, SSH_INVALID_USER));
#endif
}
#ifdef USE_PAM
if (options.use_pam)
- PRIVSEP(start_pam(authctxt));
+ PRIVSEP(start_pam(ssh));
#endif
+ ssh_packet_set_log_preamble(ssh, "%suser %s",
+ authctxt->valid ? "authenticating " : "invalid ", user);
setproctitle("%s%s", authctxt->valid ? user : "unknown",
use_privsep ? " [net]" : "");
authctxt->service = xstrdup(service);
authctxt->style = style ? xstrdup(style) : NULL;
if (use_privsep)
mm_inform_authserv(service, style);
- userauth_banner();
+ userauth_banner(ssh);
if (auth2_setup_methods_lists(authctxt) != 0)
- packet_disconnect("no authentication methods enabled");
+ ssh_packet_disconnect(ssh,
+ "no authentication methods enabled");
} else if (strcmp(user, authctxt->user) != 0 ||
strcmp(service, authctxt->service) != 0) {
- packet_disconnect("Change of username or service not allowed: "
- "(%s,%s) -> (%s,%s)",
+ ssh_packet_disconnect(ssh, "Change of username or service "
+ "not allowed: (%s,%s) -> (%s,%s)",
authctxt->user, authctxt->service, user, service);
}
/* reset state */
- auth2_challenge_stop(authctxt);
+ auth2_challenge_stop(ssh);
#ifdef GSSAPI
/* XXX move to auth2_gssapi_stop() */
- dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
- dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
+ ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
+ ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
#endif
+ auth2_authctxt_reset_info(authctxt);
authctxt->postponed = 0;
authctxt->server_caused_failure = 0;
@@ -278,22 +334,27 @@ input_userauth_request(int type, u_int32_t seq, void *ctxt)
m = authmethod_lookup(authctxt, method);
if (m != NULL && authctxt->failures < options.max_authtries) {
debug2("input_userauth_request: try method %s", method);
- authenticated = m->userauth(authctxt);
+ authenticated = m->userauth(ssh);
}
- userauth_finish(authctxt, authenticated, method, NULL);
-
+ if (!authctxt->authenticated)
+ ensure_minimum_time_since(tstart,
+ user_specific_delay(authctxt->user));
+ userauth_finish(ssh, authenticated, method, NULL);
+ r = 0;
+ out:
free(service);
free(user);
free(method);
- return 0;
+ return r;
}
void
-userauth_finish(Authctxt *authctxt, int authenticated, const char *method,
+userauth_finish(struct ssh *ssh, int authenticated, const char *method,
const char *submethod)
{
+ Authctxt *authctxt = ssh->authctxt;
char *methods;
- int partial = 0;
+ int r, partial = 0;
if (!authctxt->valid && authenticated)
fatal("INTERNAL ERROR: authenticated invalid user %s",
@@ -303,10 +364,10 @@ userauth_finish(Authctxt *authctxt, int authenticated, const char *method,
/* Special handling for root */
if (authenticated && authctxt->pw->pw_uid == 0 &&
- !auth_root_allowed(method)) {
+ !auth_root_allowed(ssh, method)) {
authenticated = 0;
#ifdef SSH_AUDIT_EVENTS
- PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED));
+ PRIVSEP(audit_event(ssh, SSH_LOGIN_ROOT_DENIED));
#endif
}
@@ -318,19 +379,30 @@ userauth_finish(Authctxt *authctxt, int authenticated, const char *method,
}
/* Log before sending the reply */
- auth_log(authctxt, authenticated, partial, method, submethod);
+ auth_log(ssh, authenticated, partial, method, submethod);
+
+ /* Update information exposed to session */
+ if (authenticated || partial)
+ auth2_update_session_info(authctxt, method, submethod);
if (authctxt->postponed)
return;
#ifdef USE_PAM
if (options.use_pam && authenticated) {
+ int r;
+
if (!PRIVSEP(do_pam_account())) {
/* if PAM returned a message, send it to the user */
- if (buffer_len(&loginmsg) > 0) {
- buffer_append(&loginmsg, "\0", 1);
- userauth_send_banner(buffer_ptr(&loginmsg));
- packet_write_wait();
+ if (sshbuf_len(loginmsg) > 0) {
+ if ((r = sshbuf_put(loginmsg, "\0", 1)) != 0)
+ fatal("%s: buffer error: %s",
+ __func__, ssh_err(r));
+ userauth_send_banner(ssh, sshbuf_ptr(loginmsg));
+ if ((r = ssh_packet_write_wait(ssh)) != 0) {
+ sshpkt_fatal(ssh, r,
+ "%s: send PAM banner", __func__);
+ }
}
fatal("Access denied for user %s by PAM account "
"configuration", authctxt->user);
@@ -338,41 +410,37 @@ userauth_finish(Authctxt *authctxt, int authenticated, const char *method,
}
#endif
-#ifdef _UNICOS
- if (authenticated && cray_access_denied(authctxt->user)) {
- authenticated = 0;
- fatal("Access denied for user %s.", authctxt->user);
- }
-#endif /* _UNICOS */
-
if (authenticated == 1) {
/* turn off userauth */
- dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
- packet_start(SSH2_MSG_USERAUTH_SUCCESS);
- packet_send();
- packet_write_wait();
+ ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST,
+ &dispatch_protocol_ignore);
+ if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_SUCCESS)) != 0 ||
+ (r = sshpkt_send(ssh)) != 0 ||
+ (r = ssh_packet_write_wait(ssh)) != 0)
+ fatal("%s: %s", __func__, ssh_err(r));
/* now we can break out */
authctxt->success = 1;
+ ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user);
} else {
-
/* Allow initial try of "none" auth without failure penalty */
if (!partial && !authctxt->server_caused_failure &&
(authctxt->attempt > 1 || strcmp(method, "none") != 0))
authctxt->failures++;
if (authctxt->failures >= options.max_authtries) {
#ifdef SSH_AUDIT_EVENTS
- PRIVSEP(audit_event(SSH_LOGIN_EXCEED_MAXTRIES));
+ PRIVSEP(audit_event(ssh, SSH_LOGIN_EXCEED_MAXTRIES));
#endif
- auth_maxtries_exceeded(authctxt);
+ auth_maxtries_exceeded(ssh);
}
methods = authmethods_get(authctxt);
debug3("%s: failure partial=%d next methods=\"%s\"", __func__,
partial, methods);
- packet_start(SSH2_MSG_USERAUTH_FAILURE);
- packet_put_cstring(methods);
- packet_put_char(partial);
- packet_send();
- packet_write_wait();
+ if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_FAILURE)) != 0 ||
+ (r = sshpkt_put_cstring(ssh, methods)) != 0 ||
+ (r = sshpkt_put_u8(ssh, partial)) != 0 ||
+ (r = sshpkt_send(ssh)) != 0 ||
+ (r = ssh_packet_write_wait(ssh)) != 0)
+ fatal("%s: %s", __func__, ssh_err(r));
free(methods);
}
}
@@ -405,11 +473,12 @@ auth2_method_allowed(Authctxt *authctxt, const char *method,
static char *
authmethods_get(Authctxt *authctxt)
{
- Buffer b;
+ struct sshbuf *b;
char *list;
- u_int i;
+ int i, r;
- buffer_init(&b);
+ if ((b = sshbuf_new()) == NULL)
+ fatal("%s: sshbuf_new failed", __func__);
for (i = 0; authmethods[i] != NULL; i++) {
if (strcmp(authmethods[i]->name, "none") == 0)
continue;
@@ -419,14 +488,13 @@ authmethods_get(Authctxt *authctxt)
if (!auth2_method_allowed(authctxt, authmethods[i]->name,
NULL))
continue;
- if (buffer_len(&b) > 0)
- buffer_append(&b, ",", 1);
- buffer_append(&b, authmethods[i]->name,
- strlen(authmethods[i]->name));
+ if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) ? "," : "",
+ authmethods[i]->name)) != 0)
+ fatal("%s: buffer error: %s", __func__, ssh_err(r));
}
- buffer_append(&b, "\0", 1);
- list = xstrdup(buffer_ptr(&b));
- buffer_free(&b);
+ if ((list = sshbuf_dup_string(b)) == NULL)
+ fatal("%s: sshbuf_dup_string failed", __func__);
+ sshbuf_free(b);
return list;
}
@@ -507,6 +575,14 @@ auth2_setup_methods_lists(Authctxt *authctxt)
{
u_int i;
+ /* First, normalise away the "any" pseudo-method */
+ if (options.num_auth_methods == 1 &&
+ strcmp(options.auth_methods[0], "any") == 0) {
+ free(options.auth_methods[0]);
+ options.auth_methods[0] = NULL;
+ options.num_auth_methods = 0;
+ }
+
if (options.num_auth_methods == 0)
return 0;
debug3("%s: checking methods", __func__);
@@ -616,4 +692,128 @@ auth2_update_methods_lists(Authctxt *authctxt, const char *method,
return 0;
}
+/* Reset method-specific information */
+void auth2_authctxt_reset_info(Authctxt *authctxt)
+{
+ sshkey_free(authctxt->auth_method_key);
+ free(authctxt->auth_method_info);
+ authctxt->auth_method_key = NULL;
+ authctxt->auth_method_info = NULL;
+}
+
+/* Record auth method-specific information for logs */
+void
+auth2_record_info(Authctxt *authctxt, const char *fmt, ...)
+{
+ va_list ap;
+ int i;
+
+ free(authctxt->auth_method_info);
+ authctxt->auth_method_info = NULL;
+
+ va_start(ap, fmt);
+ i = vasprintf(&authctxt->auth_method_info, fmt, ap);
+ va_end(ap);
+
+ if (i == -1)
+ fatal("%s: vasprintf failed", __func__);
+}
+
+/*
+ * Records a public key used in authentication. This is used for logging
+ * and to ensure that the same key is not subsequently accepted again for
+ * multiple authentication.
+ */
+void
+auth2_record_key(Authctxt *authctxt, int authenticated,
+ const struct sshkey *key)
+{
+ struct sshkey **tmp, *dup;
+ int r;
+
+ if ((r = sshkey_from_private(key, &dup)) != 0)
+ fatal("%s: copy key: %s", __func__, ssh_err(r));
+ sshkey_free(authctxt->auth_method_key);
+ authctxt->auth_method_key = dup;
+
+ if (!authenticated)
+ return;
+
+ /* If authenticated, make sure we don't accept this key again */
+ if ((r = sshkey_from_private(key, &dup)) != 0)
+ fatal("%s: copy key: %s", __func__, ssh_err(r));
+ if (authctxt->nprev_keys >= INT_MAX ||
+ (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys,
+ authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL)
+ fatal("%s: reallocarray failed", __func__);
+ authctxt->prev_keys = tmp;
+ authctxt->prev_keys[authctxt->nprev_keys] = dup;
+ authctxt->nprev_keys++;
+
+}
+
+/* Checks whether a key has already been previously used for authentication */
+int
+auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key)
+{
+ u_int i;
+ char *fp;
+
+ for (i = 0; i < authctxt->nprev_keys; i++) {
+ if (sshkey_equal_public(key, authctxt->prev_keys[i])) {
+ fp = sshkey_fingerprint(authctxt->prev_keys[i],
+ options.fingerprint_hash, SSH_FP_DEFAULT);
+ debug3("%s: key already used: %s %s", __func__,
+ sshkey_type(authctxt->prev_keys[i]),
+ fp == NULL ? "UNKNOWN" : fp);
+ free(fp);
+ return 1;
+ }
+ }
+ return 0;
+}
+
+/*
+ * Updates authctxt->session_info with details of authentication. Should be
+ * whenever an authentication method succeeds.
+ */
+void
+auth2_update_session_info(Authctxt *authctxt, const char *method,
+ const char *submethod)
+{
+ int r;
+
+ if (authctxt->session_info == NULL) {
+ if ((authctxt->session_info = sshbuf_new()) == NULL)
+ fatal("%s: sshbuf_new", __func__);
+ }
+
+ /* Append method[/submethod] */
+ if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s",
+ method, submethod == NULL ? "" : "/",
+ submethod == NULL ? "" : submethod)) != 0)
+ fatal("%s: append method: %s", __func__, ssh_err(r));
+
+ /* Append key if present */
+ if (authctxt->auth_method_key != NULL) {
+ if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 ||
+ (r = sshkey_format_text(authctxt->auth_method_key,
+ authctxt->session_info)) != 0)
+ fatal("%s: append key: %s", __func__, ssh_err(r));
+ }
+
+ if (authctxt->auth_method_info != NULL) {
+ /* Ensure no ambiguity here */
+ if (strchr(authctxt->auth_method_info, '\n') != NULL)
+ fatal("%s: auth_method_info contains \\n", __func__);
+ if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 ||
+ (r = sshbuf_putf(authctxt->session_info, "%s",
+ authctxt->auth_method_info)) != 0) {
+ fatal("%s: append method info: %s",
+ __func__, ssh_err(r));
+ }
+ }
+ if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0)
+ fatal("%s: append: %s", __func__, ssh_err(r));
+}
generated by cgit v1.2.3 (git 2.25.1) at 2025-10-03 02:19:11 +0000