[openssh.git] / gss-serv.c

/*	$OpenBSD: gss-serv.c,v 1.14 2006/02/08 13:15:44 stevesk 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++;
	}
}


/* 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
Commit	Line	Data
1720c23b	1	/* $OpenBSD: gss-serv.c,v 1.14 2006/02/08 13:15:44 stevesk Exp $ */
7364bd04	2
	3	/*
	4	* Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved.
	5	*
	6	* Redistribution and use in source and binary forms, with or without
	7	* modification, are permitted provided that the following conditions
	8	* are met:
	9	* 1. Redistributions of source code must retain the above copyright
	10	* notice, this list of conditions and the following disclaimer.
	11	* 2. Redistributions in binary form must reproduce the above copyright
	12	* notice, this list of conditions and the following disclaimer in the
	13	* documentation and/or other materials provided with the distribution.
	14	*
	15	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR
	16	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	17	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	18	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	19	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	20	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	21	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	22	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	23	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	24	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	25	*/
	26
	27	#include "includes.h"
	28
	29	#ifdef GSSAPI
	30
	31	#include "bufaux.h"
7364bd04	32	#include "auth.h"
	33	#include "log.h"
	34	#include "channels.h"
	35	#include "session.h"
	36	#include "servconf.h"
7364bd04	37	#include "xmalloc.h"
	38	#include "getput.h"
	39
	40	#include "ssh-gss.h"
	41
7364bd04	42	static ssh_gssapi_client gssapi_client =
	43	{ GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER,
	44	GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL}};
	45
	46	ssh_gssapi_mech gssapi_null_mech =
	47	{ NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL};
	48
	49	#ifdef KRB5
	50	extern ssh_gssapi_mech gssapi_kerberos_mech;
	51	#endif
	52
	53	ssh_gssapi_mech* supported_mechs[]= {
	54	#ifdef KRB5
	55	&gssapi_kerberos_mech,
	56	#endif
	57	&gssapi_null_mech,
	58	};
	59
6e902aec	60	/* Unprivileged */
7364bd04	61	void
	62	ssh_gssapi_supported_oids(gss_OID_set *oidset)
	63	{
	64	int i = 0;
	65	OM_uint32 min_status;
	66	int present;
	67	gss_OID_set supported;
	68
	69	gss_create_empty_oid_set(&min_status, oidset);
	70	gss_indicate_mechs(&min_status, &supported);
	71
	72	while (supported_mechs[i]->name != NULL) {
	73	if (GSS_ERROR(gss_test_oid_set_member(&min_status,
	74	&supported_mechs[i]->oid, supported, &present)))
	75	present = 0;
	76	if (present)
	77	gss_add_oid_set_member(&min_status,
	78	&supported_mechs[i]->oid, oidset);
	79	i++;
	80	}
	81	}
	82
	83
	84	/* Wrapper around accept_sec_context
	85	* Requires that the context contains:
	86	* oid
	87	* credentials (from ssh_gssapi_acquire_cred)
	88	*/
6e902aec	89	/* Privileged */
7364bd04	90	OM_uint32
	91	ssh_gssapi_accept_ctx(Gssctxt ctx, gss_buffer_desc recv_tok,
	92	gss_buffer_desc send_tok, OM_uint32 flags)
	93	{
	94	OM_uint32 status;
	95	gss_OID mech;
	96
	97	ctx->major = gss_accept_sec_context(&ctx->minor,
	98	&ctx->context, ctx->creds, recv_tok,
	99	GSS_C_NO_CHANNEL_BINDINGS, &ctx->client, &mech,
	100	send_tok, flags, NULL, &ctx->client_creds);
	101
	102	if (GSS_ERROR(ctx->major))
	103	ssh_gssapi_error(ctx);
	104
	105	if (ctx->client_creds)
	106	debug("Received some client credentials");
	107	else
	108	debug("Got no client credentials");
	109
	110	status = ctx->major;
	111
	112	/* Now, if we're complete and we have the right flags, then
	113	* we flag the user as also having been authenticated
	114	*/
	115
	116	if (((flags == NULL) \|\| ((*flags & GSS_C_MUTUAL_FLAG) &&
	117	(*flags & GSS_C_INTEG_FLAG))) && (ctx->major == GSS_S_COMPLETE)) {
	118	if (ssh_gssapi_getclient(ctx, &gssapi_client))
	119	fatal("Couldn't convert client name");
	120	}
	121
	122	return (status);
	123	}
	124
	125	/*
	126	* This parses an exported name, extracting the mechanism specific portion
	127	* to use for ACL checking. It verifies that the name belongs the mechanism
	128	* originally selected.
	129	*/
	130	static OM_uint32
	131	ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name)
	132	{
2ceb8101	133	u_char *tok;
7364bd04	134	OM_uint32 offset;
7364bd04	135	OM_uint32 oidl;
a7958e7b	136
8442cc66	137	tok = ename->value;
a7958e7b	138
	139	/*
	140	* Check that ename is long enough for all of the fixed length
7364bd04	141	* header, and that the initial ID bytes are correct
	142	*/
	143
8442cc66	144	if (ename->length < 6 \|\| memcmp(tok, "\x04\x01", 2) != 0)
7364bd04	145	return GSS_S_FAILURE;
	146
	147	/*
	148	* Extract the OID, and check it. Here GSSAPI breaks with tradition
	149	* and does use the OID type and length bytes. To confuse things
	150	* there are two lengths - the first including these, and the
	151	* second without.
	152	*/
	153
	154	oidl = GET_16BIT(tok+2); /* length including next two bytes */
	155	oidl = oidl-2; /* turn it into the _real_ length of the variable OID */
	156
	157	/*
	158	* Check the BER encoding for correct type and length, that the
	159	* string is long enough and that the OID matches that in our context
	160	*/
	161	if (tok[4] != 0x06 \|\| tok[5] != oidl \|\|
a7958e7b	162	ename->length < oidl+6 \|\|
8442cc66	163	!ssh_gssapi_check_oid(ctx, tok+6, oidl))
7364bd04	164	return GSS_S_FAILURE;
	165
	166	offset = oidl+6;
a7958e7b	167
7364bd04	168	if (ename->length < offset+4)
7364bd04	169	return GSS_S_FAILURE;
a7958e7b	170
7364bd04	171	name->length = GET_32BIT(tok+offset);
7364bd04	172	offset += 4;
a7958e7b	173
7364bd04	174	if (ename->length < offset+name->length)
a7958e7b	175	return GSS_S_FAILURE;
a7958e7b	176
96573c26	177	name->value = xmalloc(name->length+1);
1720c23b	178	memcpy(name->value, tok+offset, name->length);
96573c26	179	((char *)name->value)[name->length] = 0;
96573c26	180
7364bd04	181	return GSS_S_COMPLETE;
a7958e7b	182	}
7364bd04	183
	184	/* Extract the client details from a given context. This can only reliably
	185	* be called once for a context */
	186
6e902aec	187	/* Privileged (called from accept_secure_ctx) */
7364bd04	188	OM_uint32
	189	ssh_gssapi_getclient(Gssctxt ctx, ssh_gssapi_client client)
	190	{
	191	int i = 0;
	192
	193	gss_buffer_desc ename;
a7958e7b	194
7364bd04	195	client->mech = NULL;
	196
	197	while (supported_mechs[i]->name != NULL) {
	198	if (supported_mechs[i]->oid.length == ctx->oid->length &&
	199	(memcmp(supported_mechs[i]->oid.elements,
	200	ctx->oid->elements, ctx->oid->length) == 0))
	201	client->mech = supported_mechs[i];
	202	i++;
	203	}
	204
a7958e7b	205	if (client->mech == NULL)
7364bd04	206	return GSS_S_FAILURE;
a7958e7b	207
a7958e7b	208	if ((ctx->major = gss_display_name(&ctx->minor, ctx->client,
7364bd04	209	&client->displayname, NULL))) {
a7958e7b	210	ssh_gssapi_error(ctx);
a7958e7b	211	return (ctx->major);
7364bd04	212	}
a7958e7b	213
a7958e7b	214	if ((ctx->major = gss_export_name(&ctx->minor, ctx->client,
7364bd04	215	&ename))) {
	216	ssh_gssapi_error(ctx);
	217	return (ctx->major);
	218	}
a7958e7b	219
7364bd04	220	if ((ctx->major = ssh_gssapi_parse_ename(ctx,&ename,
	221	&client->exportedname))) {
	222	return (ctx->major);
	223	}
	224
	225	/* We can't copy this structure, so we just move the pointer to it */
	226	client->creds = ctx->client_creds;
	227	ctx->client_creds = GSS_C_NO_CREDENTIAL;
	228	return (ctx->major);
	229	}
	230
2362db19	231	/* As user - called on fatal/exit */
7364bd04	232	void
2362db19	233	ssh_gssapi_cleanup_creds(void)
7364bd04	234	{
	235	if (gssapi_client.store.filename != NULL) {
	236	/* Unlink probably isn't sufficient */
1720c23b	237	debug("removing gssapi cred file\"%s\"",
1720c23b	238	gssapi_client.store.filename);
7364bd04	239	unlink(gssapi_client.store.filename);
	240	}
	241	}
	242
	243	/* As user */
	244	void
	245	ssh_gssapi_storecreds(void)
	246	{
	247	if (gssapi_client.mech && gssapi_client.mech->storecreds) {
	248	(*gssapi_client.mech->storecreds)(&gssapi_client);
7364bd04	249	} else
	250	debug("ssh_gssapi_storecreds: Not a GSSAPI mechanism");
	251	}
	252
	253	/* This allows GSSAPI methods to do things to the childs environment based
	254	* on the passed authentication process and credentials.
	255	*/
	256	/* As user */
	257	void
	258	ssh_gssapi_do_child(char **envp, u_int envsizep)
	259	{
	260
	261	if (gssapi_client.store.envvar != NULL &&
	262	gssapi_client.store.envval != NULL) {
7364bd04	263	debug("Setting %s to %s", gssapi_client.store.envvar,
8442cc66	264	gssapi_client.store.envval);
7364bd04	265	child_set_env(envp, envsizep, gssapi_client.store.envvar,
4e2e5cfd	266	gssapi_client.store.envval);
7364bd04	267	}
	268	}
	269
67003554	270	/* Privileged */
7364bd04	271	int
	272	ssh_gssapi_userok(char *user)
	273	{
fe206de9	274	OM_uint32 lmin;
fe206de9	275
7364bd04	276	if (gssapi_client.exportedname.length == 0 \|\|
	277	gssapi_client.exportedname.value == NULL) {
	278	debug("No suitable client data");
	279	return 0;
	280	}
	281	if (gssapi_client.mech && gssapi_client.mech->userok)
fe206de9	282	if ((*gssapi_client.mech->userok)(&gssapi_client, user))
	283	return 1;
	284	else {
	285	/* Destroy delegated credentials if userok fails */
	286	gss_release_buffer(&lmin, &gssapi_client.displayname);
	287	gss_release_buffer(&lmin, &gssapi_client.exportedname);
	288	gss_release_cred(&lmin, &gssapi_client.creds);
	289	memset(&gssapi_client, 0, sizeof(ssh_gssapi_client));
	290	return 0;
	291	}
7364bd04	292	else
	293	debug("ssh_gssapi_userok: Unknown GSSAPI mechanism");
	294	return (0);
	295	}
	296
6e902aec	297	/* Privileged */
0789992b	298	OM_uint32
	299	ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic)
	300	{
	301	ctx->major = gss_verify_mic(&ctx->minor, ctx->context,
	302	gssbuf, gssmic, NULL);
	303
	304	return (ctx->major);
	305	}
	306
7364bd04	307	#endif