/* $NetBSD: gss-genr.c,v 1.10.2.1 2023/12/25 12:31:04 martin Exp $ */ /* $OpenBSD: gss-genr.c,v 1.28 2021/01/27 10:05:28 djm Exp $ */ /* * Copyright (c) 2001-2007 Simon Wilkinson. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #include "includes.h" __RCSID("$NetBSD"); #ifdef GSSAPI #include #include #include #include #include #include "xmalloc.h" #include "ssherr.h" #include "sshbuf.h" #include "log.h" #include "ssh2.h" #include "ssh-gss.h" /* sshbuf_get for gss_buffer_desc */ int ssh_gssapi_get_buffer_desc(struct sshbuf *b, gss_buffer_desc *g) { int r; u_char *p; size_t len; if ((r = sshbuf_get_string(b, &p, &len)) != 0) return r; g->value = p; g->length = len; return 0; } /* Check that the OID in a data stream matches that in the context */ int ssh_gssapi_check_oid(Gssctxt *ctx, void *data, size_t len) { return (ctx != NULL && ctx->oid != GSS_C_NO_OID && ctx->oid->length == len && memcmp(ctx->oid->elements, data, len) == 0); } /* Set the contexts OID from a data stream */ void ssh_gssapi_set_oid_data(Gssctxt *ctx, void *data, size_t len) { if (ctx->oid != GSS_C_NO_OID) { free(ctx->oid->elements); free(ctx->oid); } ctx->oid = xcalloc(1, sizeof(gss_OID_desc)); ctx->oid->length = len; ctx->oid->elements = xmalloc(len); memcpy(ctx->oid->elements, data, len); } /* Set the contexts OID */ void ssh_gssapi_set_oid(Gssctxt *ctx, gss_OID oid) { ssh_gssapi_set_oid_data(ctx, oid->elements, oid->length); } /* All this effort to report an error ... */ void ssh_gssapi_error(Gssctxt *ctxt) { char *s; s = ssh_gssapi_last_error(ctxt, NULL, NULL); debug("%s", s); free(s); } char * ssh_gssapi_last_error(Gssctxt *ctxt, OM_uint32 *major_status, OM_uint32 *minor_status) { OM_uint32 lmin; gss_buffer_desc msg = GSS_C_EMPTY_BUFFER; OM_uint32 ctx; struct sshbuf *b; char *ret; int r; if ((b = sshbuf_new()) == NULL) fatal_f("sshbuf_new failed"); if (major_status != NULL) *major_status = ctxt->major; if (minor_status != NULL) *minor_status = ctxt->minor; ctx = 0; /* The GSSAPI error */ do { gss_display_status(&lmin, ctxt->major, GSS_C_GSS_CODE, ctxt->oid, &ctx, &msg); if ((r = sshbuf_put(b, msg.value, msg.length)) != 0 || (r = sshbuf_put_u8(b, '\n')) != 0) fatal_fr(r, "assemble GSS_CODE"); gss_release_buffer(&lmin, &msg); } while (ctx != 0); /* The mechanism specific error */ do { gss_display_status(&lmin, ctxt->minor, GSS_C_MECH_CODE, ctxt->oid, &ctx, &msg); if ((r = sshbuf_put(b, msg.value, msg.length)) != 0 || (r = sshbuf_put_u8(b, '\n')) != 0) fatal_fr(r, "assemble MECH_CODE"); gss_release_buffer(&lmin, &msg); } while (ctx != 0); if ((r = sshbuf_put_u8(b, '\n')) != 0) fatal_fr(r, "assemble newline"); ret = xstrdup((const char *)sshbuf_ptr(b)); sshbuf_free(b); return (ret); } /* * Initialise our GSSAPI context. We use this opaque structure to contain all * of the data which both the client and server need to persist across * {accept,init}_sec_context calls, so that when we do it from the userauth * stuff life is a little easier */ void ssh_gssapi_build_ctx(Gssctxt **ctx) { *ctx = xcalloc(1, sizeof (Gssctxt)); (*ctx)->context = GSS_C_NO_CONTEXT; (*ctx)->name = GSS_C_NO_NAME; (*ctx)->oid = GSS_C_NO_OID; (*ctx)->creds = GSS_C_NO_CREDENTIAL; (*ctx)->client = GSS_C_NO_NAME; (*ctx)->client_creds = GSS_C_NO_CREDENTIAL; } /* Delete our context, providing it has been built correctly */ void ssh_gssapi_delete_ctx(Gssctxt **ctx) { OM_uint32 ms; if ((*ctx) == NULL) return; if ((*ctx)->context != GSS_C_NO_CONTEXT) gss_delete_sec_context(&ms, &(*ctx)->context, GSS_C_NO_BUFFER); if ((*ctx)->name != GSS_C_NO_NAME) gss_release_name(&ms, &(*ctx)->name); if ((*ctx)->oid != GSS_C_NO_OID) { free((*ctx)->oid->elements); free((*ctx)->oid); (*ctx)->oid = GSS_C_NO_OID; } if ((*ctx)->creds != GSS_C_NO_CREDENTIAL) gss_release_cred(&ms, &(*ctx)->creds); if ((*ctx)->client != GSS_C_NO_NAME) gss_release_name(&ms, &(*ctx)->client); if ((*ctx)->client_creds != GSS_C_NO_CREDENTIAL) gss_release_cred(&ms, &(*ctx)->client_creds); free(*ctx); *ctx = NULL; } /* * Wrapper to init_sec_context * Requires that the context contains: * oid * server name (from ssh_gssapi_import_name) */ OM_uint32 ssh_gssapi_init_ctx(Gssctxt *ctx, int deleg_creds, gss_buffer_desc *recv_tok, gss_buffer_desc* send_tok, OM_uint32 *flags) { int deleg_flag = 0; if (deleg_creds) { deleg_flag = GSS_C_DELEG_FLAG; debug("Delegating credentials"); } ctx->major = gss_init_sec_context(&ctx->minor, GSS_C_NO_CREDENTIAL, &ctx->context, ctx->name, ctx->oid, GSS_C_MUTUAL_FLAG | GSS_C_INTEG_FLAG | deleg_flag, 0, NULL, recv_tok, NULL, send_tok, flags, NULL); if (GSS_ERROR(ctx->major)) ssh_gssapi_error(ctx); return (ctx->major); } /* Create a service name for the given host */ OM_uint32 ssh_gssapi_import_name(Gssctxt *ctx, const char *host) { gss_buffer_desc gssbuf; char *val; xasprintf(&val, "host@%s", host); gssbuf.value = val; gssbuf.length = strlen(gssbuf.value); if ((ctx->major = gss_import_name(&ctx->minor, &gssbuf, GSS_C_NT_HOSTBASED_SERVICE, &ctx->name))) ssh_gssapi_error(ctx); free(gssbuf.value); return (ctx->major); } OM_uint32 ssh_gssapi_sign(Gssctxt *ctx, gss_buffer_t buffer, gss_buffer_t hash) { if ((ctx->major = gss_get_mic(&ctx->minor, ctx->context, GSS_C_QOP_DEFAULT, buffer, hash))) ssh_gssapi_error(ctx); return (ctx->major); } void ssh_gssapi_buildmic(struct sshbuf *b, const char *user, const char *service, const char *context, const struct sshbuf *session_id) { int r; sshbuf_reset(b); if ((r = sshbuf_put_stringb(b, session_id)) != 0 || (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 || (r = sshbuf_put_cstring(b, user)) != 0 || (r = sshbuf_put_cstring(b, service)) != 0 || (r = sshbuf_put_cstring(b, context)) != 0) fatal_fr(r, "assemble buildmic"); } int ssh_gssapi_check_mechanism(Gssctxt **ctx, gss_OID oid, const char *host) { gss_buffer_desc token = GSS_C_EMPTY_BUFFER; OM_uint32 major, minor; gss_OID_desc spnego_oid = {6, __UNCONST("\x2B\x06\x01\x05\x05\x02")}; /* RFC 4462 says we MUST NOT do SPNEGO */ if (oid->length == spnego_oid.length && (memcmp(oid->elements, spnego_oid.elements, oid->length) == 0)) return 0; /* false */ ssh_gssapi_build_ctx(ctx); ssh_gssapi_set_oid(*ctx, oid); major = ssh_gssapi_import_name(*ctx, host); if (!GSS_ERROR(major)) { major = ssh_gssapi_init_ctx(*ctx, 0, GSS_C_NO_BUFFER, &token, NULL); gss_release_buffer(&minor, &token); if ((*ctx)->context != GSS_C_NO_CONTEXT) gss_delete_sec_context(&minor, &(*ctx)->context, GSS_C_NO_BUFFER); } if (GSS_ERROR(major)) ssh_gssapi_delete_ctx(ctx); return (!GSS_ERROR(major)); } #endif /* GSSAPI */