gss-serv.c - platform/external/openssh - Gitiles

 /* $OpenBSD: gss-serv.c,v 1.16 2006/03/25 22:22:43 djm Exp $ */

 /*
  * Copyright (c) 2001-2003 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"

 #ifdef GSSAPI

 #include "bufaux.h"
 #include "auth.h"
 #include "log.h"
 #include "channels.h"
 #include "session.h"
 #include "servconf.h"
 #include "xmalloc.h"
 #include "getput.h"

 #include "ssh-gss.h"

 static ssh_gssapi_client gssapi_client =
     { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER,
     GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL}};

 ssh_gssapi_mech gssapi_null_mech =
     { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL};

 #ifdef KRB5
 extern ssh_gssapi_mech gssapi_kerberos_mech;
 #endif

 ssh_gssapi_mech* supported_mechs[]= {
 #ifdef KRB5
 	&gssapi_kerberos_mech,
 #endif
 	&gssapi_null_mech,
 };

 /* Unprivileged */
 void
 ssh_gssapi_supported_oids(gss_OID_set *oidset)
 {
 	int i = 0;
 	OM_uint32 min_status;
 	int present;
 	gss_OID_set supported;

 	gss_create_empty_oid_set(&min_status, oidset);
 	gss_indicate_mechs(&min_status, &supported);

 	while (supported_mechs[i]->name != NULL) {
 		if (GSS_ERROR(gss_test_oid_set_member(&min_status,
 		    &supported_mechs[i]->oid, supported, &present)))
 			present = 0;
 		if (present)
 			gss_add_oid_set_member(&min_status,
 			    &supported_mechs[i]->oid, oidset);
 		i++;
 	}

 	gss_release_oid_set(&min_status, &supported);
 }


 /* Wrapper around accept_sec_context
  * Requires that the context contains:
  *    oid
  *    credentials	(from ssh_gssapi_acquire_cred)
  */
 /* Privileged */
 OM_uint32
 ssh_gssapi_accept_ctx(Gssctxt *ctx, gss_buffer_desc *recv_tok,
     gss_buffer_desc *send_tok, OM_uint32 *flags)
 {
 	OM_uint32 status;
 	gss_OID mech;

 	ctx->major = gss_accept_sec_context(&ctx->minor,
 	    &ctx->context, ctx->creds, recv_tok,
 	    GSS_C_NO_CHANNEL_BINDINGS, &ctx->client, &mech,
 	    send_tok, flags, NULL, &ctx->client_creds);

 	if (GSS_ERROR(ctx->major))
 		ssh_gssapi_error(ctx);

 	if (ctx->client_creds)
 		debug("Received some client credentials");
 	else
 		debug("Got no client credentials");

 	status = ctx->major;

 	/* Now, if we're complete and we have the right flags, then
 	 * we flag the user as also having been authenticated
 	 */

 	if (((flags == NULL) || ((*flags & GSS_C_MUTUAL_FLAG) &&
 	    (*flags & GSS_C_INTEG_FLAG))) && (ctx->major == GSS_S_COMPLETE)) {
 		if (ssh_gssapi_getclient(ctx, &gssapi_client))
 			fatal("Couldn't convert client name");
 	}

 	return (status);
 }

 /*
  * This parses an exported name, extracting the mechanism specific portion
  * to use for ACL checking. It verifies that the name belongs the mechanism
  * originally selected.
  */
 static OM_uint32
 ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name)
 {
 	u_char *tok;
 	OM_uint32 offset;
 	OM_uint32 oidl;

 	tok = ename->value;

 	/*
 	 * Check that ename is long enough for all of the fixed length
 	 * header, and that the initial ID bytes are correct
 	 */

 	if (ename->length < 6 || memcmp(tok, "\x04\x01", 2) != 0)
 		return GSS_S_FAILURE;

 	/*
 	 * Extract the OID, and check it. Here GSSAPI breaks with tradition
 	 * and does use the OID type and length bytes. To confuse things
 	 * there are two lengths - the first including these, and the
 	 * second without.
 	 */

 	oidl = GET_16BIT(tok+2); /* length including next two bytes */
 	oidl = oidl-2; /* turn it into the _real_ length of the variable OID */

 	/*
 	 * Check the BER encoding for correct type and length, that the
 	 * string is long enough and that the OID matches that in our context
 	 */
 	if (tok[4] != 0x06 || tok[5] != oidl ||
 	    ename->length < oidl+6 ||
 	    !ssh_gssapi_check_oid(ctx, tok+6, oidl))
 		return GSS_S_FAILURE;

 	offset = oidl+6;

 	if (ename->length < offset+4)
 		return GSS_S_FAILURE;

 	name->length = GET_32BIT(tok+offset);
 	offset += 4;

 	if (ename->length < offset+name->length)
 		return GSS_S_FAILURE;

 	name->value = xmalloc(name->length+1);
 	memcpy(name->value, tok+offset, name->length);
 	((char *)name->value)[name->length] = 0;

 	return GSS_S_COMPLETE;
 }

 /* Extract the client details from a given context. This can only reliably
  * be called once for a context */

 /* Privileged (called from accept_secure_ctx) */
 OM_uint32
 ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client)
 {
 	int i = 0;

 	gss_buffer_desc ename;

 	client->mech = NULL;

 	while (supported_mechs[i]->name != NULL) {
 		if (supported_mechs[i]->oid.length == ctx->oid->length &&
 		    (memcmp(supported_mechs[i]->oid.elements,
 		    ctx->oid->elements, ctx->oid->length) == 0))
 			client->mech = supported_mechs[i];
 		i++;
 	}

 	if (client->mech == NULL)
 		return GSS_S_FAILURE;

 	if ((ctx->major = gss_display_name(&ctx->minor, ctx->client,
 	    &client->displayname, NULL))) {
 		ssh_gssapi_error(ctx);
 		return (ctx->major);
 	}

 	if ((ctx->major = gss_export_name(&ctx->minor, ctx->client,
 	    &ename))) {
 		ssh_gssapi_error(ctx);
 		return (ctx->major);
 	}

 	if ((ctx->major = ssh_gssapi_parse_ename(ctx,&ename,
 	    &client->exportedname))) {
 		return (ctx->major);
 	}

 	/* We can't copy this structure, so we just move the pointer to it */
 	client->creds = ctx->client_creds;
 	ctx->client_creds = GSS_C_NO_CREDENTIAL;
 	return (ctx->major);
 }

 /* As user - called on fatal/exit */
 void
 ssh_gssapi_cleanup_creds(void)
 {
 	if (gssapi_client.store.filename != NULL) {
 		/* Unlink probably isn't sufficient */
 		debug("removing gssapi cred file\"%s\"",
 		    gssapi_client.store.filename);
 		unlink(gssapi_client.store.filename);
 	}
 }

 /* As user */
 void
 ssh_gssapi_storecreds(void)
 {
 	if (gssapi_client.mech && gssapi_client.mech->storecreds) {
 		(*gssapi_client.mech->storecreds)(&gssapi_client);
 	} else
 		debug("ssh_gssapi_storecreds: Not a GSSAPI mechanism");
 }

 /* This allows GSSAPI methods to do things to the childs environment based
  * on the passed authentication process and credentials.
  */
 /* As user */
 void
 ssh_gssapi_do_child(char ***envp, u_int *envsizep)
 {

 	if (gssapi_client.store.envvar != NULL &&
 	    gssapi_client.store.envval != NULL) {
 		debug("Setting %s to %s", gssapi_client.store.envvar,
 		    gssapi_client.store.envval);
 		child_set_env(envp, envsizep, gssapi_client.store.envvar,
 		    gssapi_client.store.envval);
 	}
 }

 /* Privileged */
 int
 ssh_gssapi_userok(char *user)
 {
 	OM_uint32 lmin;

 	if (gssapi_client.exportedname.length == 0 ||
 	    gssapi_client.exportedname.value == NULL) {
 		debug("No suitable client data");
 		return 0;
 	}
 	if (gssapi_client.mech && gssapi_client.mech->userok)
 		if ((*gssapi_client.mech->userok)(&gssapi_client, user))
 			return 1;
 		else {
 			/* Destroy delegated credentials if userok fails */
 			gss_release_buffer(&lmin, &gssapi_client.displayname);
 			gss_release_buffer(&lmin, &gssapi_client.exportedname);
 			gss_release_cred(&lmin, &gssapi_client.creds);
 			memset(&gssapi_client, 0, sizeof(ssh_gssapi_client));
 			return 0;
 		}
 	else
 		debug("ssh_gssapi_userok: Unknown GSSAPI mechanism");
 	return (0);
 }

 /* Privileged */
 OM_uint32
 ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic)
 {
 	ctx->major = gss_verify_mic(&ctx->minor, ctx->context,
 	    gssbuf, gssmic, NULL);

 	return (ctx->major);
 }

 #endif
	/* $OpenBSD: gss-serv.c,v 1.16 2006/03/25 22:22:43 djm Exp $ */

	/*
	* Copyright (c) 2001-2003 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"

	#ifdef GSSAPI

	#include "bufaux.h"
	#include "auth.h"
	#include "log.h"
	#include "channels.h"
	#include "session.h"
	#include "servconf.h"
	#include "xmalloc.h"
	#include "getput.h"

	#include "ssh-gss.h"

	static ssh_gssapi_client gssapi_client =
	{ GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER,
	GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL}};

	ssh_gssapi_mech gssapi_null_mech =
	{ NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL};

	#ifdef KRB5
	extern ssh_gssapi_mech gssapi_kerberos_mech;
	#endif

	ssh_gssapi_mech* supported_mechs[]= {
	#ifdef KRB5
	&gssapi_kerberos_mech,
	#endif
	&gssapi_null_mech,
	};

	/* Unprivileged */
	void
	ssh_gssapi_supported_oids(gss_OID_set *oidset)
	{
	int i = 0;
	OM_uint32 min_status;
	int present;
	gss_OID_set supported;

	gss_create_empty_oid_set(&min_status, oidset);
	gss_indicate_mechs(&min_status, &supported);

	while (supported_mechs[i]->name != NULL) {
	if (GSS_ERROR(gss_test_oid_set_member(&min_status,
	&supported_mechs[i]->oid, supported, &present)))
	present = 0;
	if (present)
	gss_add_oid_set_member(&min_status,
	&supported_mechs[i]->oid, oidset);
	i++;
	}

	gss_release_oid_set(&min_status, &supported);
	}


	/* Wrapper around accept_sec_context
	* Requires that the context contains:
	* oid
	* credentials (from ssh_gssapi_acquire_cred)
	*/
	/* Privileged */
	OM_uint32
	ssh_gssapi_accept_ctx(Gssctxt ctx, gss_buffer_desc recv_tok,
	gss_buffer_desc send_tok, OM_uint32 flags)
	{
	OM_uint32 status;
	gss_OID mech;

	ctx->major = gss_accept_sec_context(&ctx->minor,
	&ctx->context, ctx->creds, recv_tok,
	GSS_C_NO_CHANNEL_BINDINGS, &ctx->client, &mech,
	send_tok, flags, NULL, &ctx->client_creds);

	if (GSS_ERROR(ctx->major))
	ssh_gssapi_error(ctx);

	if (ctx->client_creds)
	debug("Received some client credentials");
	else
	debug("Got no client credentials");

	status = ctx->major;

	/* Now, if we're complete and we have the right flags, then
	* we flag the user as also having been authenticated
	*/

	if (((flags == NULL) \|\| ((*flags & GSS_C_MUTUAL_FLAG) &&
	(*flags & GSS_C_INTEG_FLAG))) && (ctx->major == GSS_S_COMPLETE)) {
	if (ssh_gssapi_getclient(ctx, &gssapi_client))
	fatal("Couldn't convert client name");
	}

	return (status);
	}

	/*
	* This parses an exported name, extracting the mechanism specific portion
	* to use for ACL checking. It verifies that the name belongs the mechanism
	* originally selected.
	*/
	static OM_uint32
	ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name)
	{
	u_char *tok;
	OM_uint32 offset;
	OM_uint32 oidl;

	tok = ename->value;

	/*
	* Check that ename is long enough for all of the fixed length
	* header, and that the initial ID bytes are correct
	*/

	if (ename->length < 6 \|\| memcmp(tok, "\x04\x01", 2) != 0)
	return GSS_S_FAILURE;

	/*
	* Extract the OID, and check it. Here GSSAPI breaks with tradition
	* and does use the OID type and length bytes. To confuse things
	* there are two lengths - the first including these, and the
	* second without.
	*/

	oidl = GET_16BIT(tok+2); /* length including next two bytes */
	oidl = oidl-2; /* turn it into the _real_ length of the variable OID */

	/*
	* Check the BER encoding for correct type and length, that the
	* string is long enough and that the OID matches that in our context
	*/
	if (tok[4] != 0x06 \|\| tok[5] != oidl \|\|
	ename->length < oidl+6 \|\|
	!ssh_gssapi_check_oid(ctx, tok+6, oidl))
	return GSS_S_FAILURE;

	offset = oidl+6;

	if (ename->length < offset+4)
	return GSS_S_FAILURE;

	name->length = GET_32BIT(tok+offset);
	offset += 4;

	if (ename->length < offset+name->length)
	return GSS_S_FAILURE;

	name->value = xmalloc(name->length+1);
	memcpy(name->value, tok+offset, name->length);
	((char *)name->value)[name->length] = 0;

	return GSS_S_COMPLETE;
	}

	/* Extract the client details from a given context. This can only reliably
	* be called once for a context */

	/* Privileged (called from accept_secure_ctx) */
	OM_uint32
	ssh_gssapi_getclient(Gssctxt ctx, ssh_gssapi_client client)
	{
	int i = 0;

	gss_buffer_desc ename;

	client->mech = NULL;

	while (supported_mechs[i]->name != NULL) {
	if (supported_mechs[i]->oid.length == ctx->oid->length &&
	(memcmp(supported_mechs[i]->oid.elements,
	ctx->oid->elements, ctx->oid->length) == 0))
	client->mech = supported_mechs[i];
	i++;
	}

	if (client->mech == NULL)
	return GSS_S_FAILURE;

	if ((ctx->major = gss_display_name(&ctx->minor, ctx->client,
	&client->displayname, NULL))) {
	ssh_gssapi_error(ctx);
	return (ctx->major);
	}

	if ((ctx->major = gss_export_name(&ctx->minor, ctx->client,
	&ename))) {
	ssh_gssapi_error(ctx);
	return (ctx->major);
	}

	if ((ctx->major = ssh_gssapi_parse_ename(ctx,&ename,
	&client->exportedname))) {
	return (ctx->major);
	}

	/* We can't copy this structure, so we just move the pointer to it */
	client->creds = ctx->client_creds;
	ctx->client_creds = GSS_C_NO_CREDENTIAL;
	return (ctx->major);
	}

	/* As user - called on fatal/exit */
	void
	ssh_gssapi_cleanup_creds(void)
	{
	if (gssapi_client.store.filename != NULL) {
	/* Unlink probably isn't sufficient */
	debug("removing gssapi cred file\"%s\"",
	gssapi_client.store.filename);
	unlink(gssapi_client.store.filename);
	}
	}

	/* As user */
	void
	ssh_gssapi_storecreds(void)
	{
	if (gssapi_client.mech && gssapi_client.mech->storecreds) {
	(*gssapi_client.mech->storecreds)(&gssapi_client);
	} else
	debug("ssh_gssapi_storecreds: Not a GSSAPI mechanism");
	}

	/* This allows GSSAPI methods to do things to the childs environment based
	* on the passed authentication process and credentials.
	*/
	/* As user */
	void
	ssh_gssapi_do_child(char **envp, u_int envsizep)
	{

	if (gssapi_client.store.envvar != NULL &&
	gssapi_client.store.envval != NULL) {
	debug("Setting %s to %s", gssapi_client.store.envvar,
	gssapi_client.store.envval);
	child_set_env(envp, envsizep, gssapi_client.store.envvar,
	gssapi_client.store.envval);
	}
	}

	/* Privileged */
	int
	ssh_gssapi_userok(char *user)
	{
	OM_uint32 lmin;

	if (gssapi_client.exportedname.length == 0 \|\|
	gssapi_client.exportedname.value == NULL) {
	debug("No suitable client data");
	return 0;
	}
	if (gssapi_client.mech && gssapi_client.mech->userok)
	if ((*gssapi_client.mech->userok)(&gssapi_client, user))
	return 1;
	else {
	/* Destroy delegated credentials if userok fails */
	gss_release_buffer(&lmin, &gssapi_client.displayname);
	gss_release_buffer(&lmin, &gssapi_client.exportedname);
	gss_release_cred(&lmin, &gssapi_client.creds);
	memset(&gssapi_client, 0, sizeof(ssh_gssapi_client));
	return 0;
	}
	else
	debug("ssh_gssapi_userok: Unknown GSSAPI mechanism");
	return (0);
	}

	/* Privileged */
	OM_uint32
	ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic)
	{
	ctx->major = gss_verify_mic(&ctx->minor, ctx->context,
	gssbuf, gssmic, NULL);

	return (ctx->major);
	}

	#endif