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delay bailout for invalid authenticating user until after the packet

containing the request has been fully parsed. Reported by Dariusz Tytko
and Michał Sajdak; ok deraadt
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djmdjm committed Jul 31, 2018
1 parent 1addc7a commit 779974d35b4859c07bc3cb8a12c74b43b0a7d1e0
Showing with 28 additions and 19 deletions.
  1. +7 −4 usr.bin/ssh/auth2-gss.c
  2. +6 −5 usr.bin/ssh/auth2-hostbased.c
  3. +15 −10 usr.bin/ssh/auth2-pubkey.c
View
@@ -1,4 +1,4 @@
/* $OpenBSD: auth2-gss.c,v 1.28 2018/07/10 09:13:30 djm Exp $ */
/* $OpenBSD: auth2-gss.c,v 1.29 2018/07/31 03:10:27 djm Exp $ */
/*
* Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved.
@@ -65,9 +65,6 @@ userauth_gssapi(struct ssh *ssh)
size_t len;
u_char *doid = NULL;
if (!authctxt->valid || authctxt->user == NULL)
return (0);
if ((r = sshpkt_get_u32(ssh, &mechs)) != 0)
fatal("%s: %s", __func__, ssh_err(r));
@@ -101,6 +98,12 @@ userauth_gssapi(struct ssh *ssh)
return (0);
}
if (!authctxt->valid || authctxt->user == NULL) {
debug2("%s: disabled because of invalid user", __func__);
free(doid);
return (0);
}
if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &goid)))) {
if (ctxt != NULL)
ssh_gssapi_delete_ctx(&ctxt);
@@ -1,4 +1,4 @@
/* $OpenBSD: auth2-hostbased.c,v 1.35 2018/07/09 21:35:50 markus Exp $ */
/* $OpenBSD: auth2-hostbased.c,v 1.36 2018/07/31 03:10:27 djm Exp $ */
/*
* Copyright (c) 2000 Markus Friedl. All rights reserved.
*
@@ -66,10 +66,6 @@ userauth_hostbased(struct ssh *ssh)
size_t alen, blen, slen;
int r, pktype, authenticated = 0;
if (!authctxt->valid) {
debug2("%s: disabled because of invalid user", __func__);
return 0;
}
/* XXX use sshkey_froms() */
if ((r = sshpkt_get_cstring(ssh, &pkalg, &alen)) != 0 ||
(r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 ||
@@ -116,6 +112,11 @@ userauth_hostbased(struct ssh *ssh)
goto done;
}
if (!authctxt->valid || authctxt->user == NULL) {
debug2("%s: disabled because of invalid user", __func__);
goto done;
}
if ((b = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
/* reconstruct packet */
View
@@ -1,4 +1,4 @@
/* $OpenBSD: auth2-pubkey.c,v 1.82 2018/07/11 18:55:11 markus Exp $ */
/* $OpenBSD: auth2-pubkey.c,v 1.83 2018/07/31 03:10:27 djm Exp $ */
/*
* Copyright (c) 2000 Markus Friedl. All rights reserved.
*
@@ -86,19 +86,15 @@ userauth_pubkey(struct ssh *ssh)
{
Authctxt *authctxt = ssh->authctxt;
struct passwd *pw = authctxt->pw;
struct sshbuf *b;
struct sshbuf *b = NULL;
struct sshkey *key = NULL;
char *pkalg, *userstyle = NULL, *key_s = NULL, *ca_s = NULL;
u_char *pkblob, *sig, have_sig;
char *pkalg = NULL, *userstyle = NULL, *key_s = NULL, *ca_s = NULL;
u_char *pkblob = NULL, *sig = NULL, have_sig;
size_t blen, slen;
int r, pktype;
int authenticated = 0;
struct sshauthopt *authopts = NULL;
if (!authctxt->valid) {
debug2("%s: disabled because of invalid user", __func__);
return 0;
}
if ((r = sshpkt_get_u8(ssh, &have_sig)) != 0 ||
(r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 ||
(r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0)
@@ -164,6 +160,11 @@ userauth_pubkey(struct ssh *ssh)
fatal("%s: sshbuf_put_string session id: %s",
__func__, ssh_err(r));
}
if (!authctxt->valid || authctxt->user == NULL) {
debug2("%s: disabled because of invalid user",
__func__);
goto done;
}
/* reconstruct packet */
xasprintf(&userstyle, "%s%s%s", authctxt->user,
authctxt->style ? ":" : "",
@@ -180,7 +181,6 @@ userauth_pubkey(struct ssh *ssh)
#ifdef DEBUG_PK
sshbuf_dump(b, stderr);
#endif
/* test for correct signature */
authenticated = 0;
if (PRIVSEP(user_key_allowed(ssh, pw, key, 1, &authopts)) &&
@@ -191,7 +191,6 @@ userauth_pubkey(struct ssh *ssh)
authenticated = 1;
}
sshbuf_free(b);
free(sig);
auth2_record_key(authctxt, authenticated, key);
} else {
debug("%s: test pkalg %s pkblob %s%s%s",
@@ -202,6 +201,11 @@ userauth_pubkey(struct ssh *ssh)
if ((r = sshpkt_get_end(ssh)) != 0)
fatal("%s: %s", __func__, ssh_err(r));
if (!authctxt->valid || authctxt->user == NULL) {
debug2("%s: disabled because of invalid user",
__func__);
goto done;
}
/* XXX fake reply and always send PK_OK ? */
/*
* XXX this allows testing whether a user is allowed
@@ -235,6 +239,7 @@ userauth_pubkey(struct ssh *ssh)
free(pkblob);
free(key_s);
free(ca_s);
free(sig);
return authenticated;
}

1 comment on commit 779974d

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owenzidane Sep 28, 2018

how to use this update kb

owenzidane commented on 779974d Sep 28, 2018

how to use this update kb

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