Some notable changes, from upstream's release notes: - sshd(8): Remove support for obsolete "host/port" syntax. - ssh(1): When prompting whether to record a new host key, accept the key fingerprint as a synonym for "yes". - ssh-keygen(1): when acting as a CA and signing certificates with an RSA key, default to using the rsa-sha2-512 signature algorithm. - ssh(1), sshd(8), ssh-keygen(1): this release removes the "ssh-rsa" (RSA/SHA1) algorithm from those accepted for certificate signatures. - ssh-sk-helper(8): this is a new binary. It is used by the FIDO/U2F support to provide address-space isolation for token middleware libraries (including the internal one). - ssh(1): this release enables UpdateHostkeys by default subject to some conservative preconditions. - scp(1): this release changes the behaviour of remote to remote copies (e.g. "scp host-a:/path host-b:") to transfer through the local host by default. - scp(1): experimental support for transfers using the SFTP protocol as a replacement for the venerable SCP/RCP protocol that it has traditionally used. Additional integration work is needed to support FIDO/U2F in the base system. Deprecation Notice ------------------ OpenSSH will disable the ssh-rsa signature scheme by default in the next release. Reviewed by: imp MFC after: 1 month Relnotes: Yes Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D29985
303 lines
7.9 KiB
C
303 lines
7.9 KiB
C
/* $OpenBSD: gss-genr.c,v 1.28 2021/01/27 10:05:28 djm Exp $ */
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/*
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* Copyright (c) 2001-2007 Simon Wilkinson. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "includes.h"
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#ifdef GSSAPI
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#include <sys/types.h>
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#include <limits.h>
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#include <stdarg.h>
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#include <string.h>
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#include <signal.h>
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#include <unistd.h>
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#include "xmalloc.h"
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#include "ssherr.h"
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#include "sshbuf.h"
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#include "log.h"
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#include "ssh2.h"
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#include "ssh-gss.h"
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/* sshbuf_get for gss_buffer_desc */
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int
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ssh_gssapi_get_buffer_desc(struct sshbuf *b, gss_buffer_desc *g)
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{
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int r;
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u_char *p;
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size_t len;
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if ((r = sshbuf_get_string(b, &p, &len)) != 0)
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return r;
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g->value = p;
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g->length = len;
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return 0;
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}
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/* Check that the OID in a data stream matches that in the context */
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int
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ssh_gssapi_check_oid(Gssctxt *ctx, void *data, size_t len)
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{
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return (ctx != NULL && ctx->oid != GSS_C_NO_OID &&
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ctx->oid->length == len &&
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memcmp(ctx->oid->elements, data, len) == 0);
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}
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/* Set the contexts OID from a data stream */
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void
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ssh_gssapi_set_oid_data(Gssctxt *ctx, void *data, size_t len)
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{
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if (ctx->oid != GSS_C_NO_OID) {
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free(ctx->oid->elements);
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free(ctx->oid);
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}
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ctx->oid = xcalloc(1, sizeof(gss_OID_desc));
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ctx->oid->length = len;
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ctx->oid->elements = xmalloc(len);
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memcpy(ctx->oid->elements, data, len);
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}
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/* Set the contexts OID */
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void
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ssh_gssapi_set_oid(Gssctxt *ctx, gss_OID oid)
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{
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ssh_gssapi_set_oid_data(ctx, oid->elements, oid->length);
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}
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/* All this effort to report an error ... */
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void
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ssh_gssapi_error(Gssctxt *ctxt)
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{
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char *s;
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s = ssh_gssapi_last_error(ctxt, NULL, NULL);
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debug("%s", s);
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free(s);
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}
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char *
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ssh_gssapi_last_error(Gssctxt *ctxt, OM_uint32 *major_status,
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OM_uint32 *minor_status)
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{
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OM_uint32 lmin;
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gss_buffer_desc msg = GSS_C_EMPTY_BUFFER;
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OM_uint32 ctx;
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struct sshbuf *b;
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char *ret;
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int r;
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if ((b = sshbuf_new()) == NULL)
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fatal_f("sshbuf_new failed");
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if (major_status != NULL)
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*major_status = ctxt->major;
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if (minor_status != NULL)
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*minor_status = ctxt->minor;
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ctx = 0;
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/* The GSSAPI error */
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do {
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gss_display_status(&lmin, ctxt->major,
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GSS_C_GSS_CODE, ctxt->oid, &ctx, &msg);
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if ((r = sshbuf_put(b, msg.value, msg.length)) != 0 ||
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(r = sshbuf_put_u8(b, '\n')) != 0)
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fatal_fr(r, "assemble GSS_CODE");
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gss_release_buffer(&lmin, &msg);
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} while (ctx != 0);
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/* The mechanism specific error */
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do {
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gss_display_status(&lmin, ctxt->minor,
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GSS_C_MECH_CODE, ctxt->oid, &ctx, &msg);
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if ((r = sshbuf_put(b, msg.value, msg.length)) != 0 ||
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(r = sshbuf_put_u8(b, '\n')) != 0)
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fatal_fr(r, "assemble MECH_CODE");
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gss_release_buffer(&lmin, &msg);
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} while (ctx != 0);
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if ((r = sshbuf_put_u8(b, '\n')) != 0)
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fatal_fr(r, "assemble newline");
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ret = xstrdup((const char *)sshbuf_ptr(b));
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sshbuf_free(b);
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return (ret);
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}
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/*
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* Initialise our GSSAPI context. We use this opaque structure to contain all
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* of the data which both the client and server need to persist across
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* {accept,init}_sec_context calls, so that when we do it from the userauth
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* stuff life is a little easier
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*/
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void
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ssh_gssapi_build_ctx(Gssctxt **ctx)
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{
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*ctx = xcalloc(1, sizeof (Gssctxt));
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(*ctx)->context = GSS_C_NO_CONTEXT;
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(*ctx)->name = GSS_C_NO_NAME;
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(*ctx)->oid = GSS_C_NO_OID;
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(*ctx)->creds = GSS_C_NO_CREDENTIAL;
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(*ctx)->client = GSS_C_NO_NAME;
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(*ctx)->client_creds = GSS_C_NO_CREDENTIAL;
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}
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/* Delete our context, providing it has been built correctly */
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void
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ssh_gssapi_delete_ctx(Gssctxt **ctx)
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{
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OM_uint32 ms;
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if ((*ctx) == NULL)
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return;
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if ((*ctx)->context != GSS_C_NO_CONTEXT)
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gss_delete_sec_context(&ms, &(*ctx)->context, GSS_C_NO_BUFFER);
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if ((*ctx)->name != GSS_C_NO_NAME)
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gss_release_name(&ms, &(*ctx)->name);
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if ((*ctx)->oid != GSS_C_NO_OID) {
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free((*ctx)->oid->elements);
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free((*ctx)->oid);
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(*ctx)->oid = GSS_C_NO_OID;
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}
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if ((*ctx)->creds != GSS_C_NO_CREDENTIAL)
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gss_release_cred(&ms, &(*ctx)->creds);
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if ((*ctx)->client != GSS_C_NO_NAME)
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gss_release_name(&ms, &(*ctx)->client);
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if ((*ctx)->client_creds != GSS_C_NO_CREDENTIAL)
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gss_release_cred(&ms, &(*ctx)->client_creds);
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free(*ctx);
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*ctx = NULL;
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}
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/*
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* Wrapper to init_sec_context
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* Requires that the context contains:
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* oid
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* server name (from ssh_gssapi_import_name)
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*/
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OM_uint32
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ssh_gssapi_init_ctx(Gssctxt *ctx, int deleg_creds, gss_buffer_desc *recv_tok,
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gss_buffer_desc* send_tok, OM_uint32 *flags)
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{
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int deleg_flag = 0;
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if (deleg_creds) {
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deleg_flag = GSS_C_DELEG_FLAG;
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debug("Delegating credentials");
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}
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ctx->major = gss_init_sec_context(&ctx->minor,
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GSS_C_NO_CREDENTIAL, &ctx->context, ctx->name, ctx->oid,
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GSS_C_MUTUAL_FLAG | GSS_C_INTEG_FLAG | deleg_flag,
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0, NULL, recv_tok, NULL, send_tok, flags, NULL);
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if (GSS_ERROR(ctx->major))
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ssh_gssapi_error(ctx);
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return (ctx->major);
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}
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/* Create a service name for the given host */
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OM_uint32
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ssh_gssapi_import_name(Gssctxt *ctx, const char *host)
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{
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gss_buffer_desc gssbuf;
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char *val;
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xasprintf(&val, "host@%s", host);
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gssbuf.value = val;
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gssbuf.length = strlen(gssbuf.value);
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if ((ctx->major = gss_import_name(&ctx->minor,
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&gssbuf, GSS_C_NT_HOSTBASED_SERVICE, &ctx->name)))
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ssh_gssapi_error(ctx);
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free(gssbuf.value);
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return (ctx->major);
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}
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OM_uint32
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ssh_gssapi_sign(Gssctxt *ctx, gss_buffer_t buffer, gss_buffer_t hash)
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{
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if ((ctx->major = gss_get_mic(&ctx->minor, ctx->context,
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GSS_C_QOP_DEFAULT, buffer, hash)))
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ssh_gssapi_error(ctx);
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return (ctx->major);
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}
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void
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ssh_gssapi_buildmic(struct sshbuf *b, const char *user, const char *service,
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const char *context, const struct sshbuf *session_id)
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{
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int r;
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sshbuf_reset(b);
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if ((r = sshbuf_put_stringb(b, session_id)) != 0 ||
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(r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
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(r = sshbuf_put_cstring(b, user)) != 0 ||
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(r = sshbuf_put_cstring(b, service)) != 0 ||
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(r = sshbuf_put_cstring(b, context)) != 0)
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fatal_fr(r, "assemble buildmic");
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}
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int
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ssh_gssapi_check_mechanism(Gssctxt **ctx, gss_OID oid, const char *host)
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{
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gss_buffer_desc token = GSS_C_EMPTY_BUFFER;
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OM_uint32 major, minor;
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gss_OID_desc spnego_oid = {6, (void *)"\x2B\x06\x01\x05\x05\x02"};
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/* RFC 4462 says we MUST NOT do SPNEGO */
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if (oid->length == spnego_oid.length &&
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(memcmp(oid->elements, spnego_oid.elements, oid->length) == 0))
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return 0; /* false */
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ssh_gssapi_build_ctx(ctx);
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ssh_gssapi_set_oid(*ctx, oid);
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major = ssh_gssapi_import_name(*ctx, host);
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if (!GSS_ERROR(major)) {
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major = ssh_gssapi_init_ctx(*ctx, 0, GSS_C_NO_BUFFER, &token,
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NULL);
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gss_release_buffer(&minor, &token);
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if ((*ctx)->context != GSS_C_NO_CONTEXT)
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gss_delete_sec_context(&minor, &(*ctx)->context,
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GSS_C_NO_BUFFER);
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}
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if (GSS_ERROR(major))
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ssh_gssapi_delete_ctx(ctx);
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return (!GSS_ERROR(major));
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}
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#endif /* GSSAPI */
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