[openssh.git] / gss-serv.c

/* $OpenBSD: gss-serv.c,v 1.18 2006/07/02 18:36:47 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 "xmalloc.h"
#include "misc.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_u16(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_u32(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
6955279c	1	/* $OpenBSD: gss-serv.c,v 1.18 2006/07/02 18:36:47 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"
7364bd04	36	#include "xmalloc.h"
51e7a012	37	#include "misc.h"
7364bd04	38
	39	#include "ssh-gss.h"
	40
7364bd04	41	static ssh_gssapi_client gssapi_client =
	42	{ GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER,
	43	GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL}};
	44
	45	ssh_gssapi_mech gssapi_null_mech =
	46	{ NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL};
	47
	48	#ifdef KRB5
	49	extern ssh_gssapi_mech gssapi_kerberos_mech;
	50	#endif
	51
	52	ssh_gssapi_mech* supported_mechs[]= {
	53	#ifdef KRB5
	54	&gssapi_kerberos_mech,
	55	#endif
	56	&gssapi_null_mech,
	57	};
	58
6e902aec	59	/* Unprivileged */
7364bd04	60	void
	61	ssh_gssapi_supported_oids(gss_OID_set *oidset)
	62	{
	63	int i = 0;
	64	OM_uint32 min_status;
	65	int present;
	66	gss_OID_set supported;
	67
	68	gss_create_empty_oid_set(&min_status, oidset);
	69	gss_indicate_mechs(&min_status, &supported);
	70
	71	while (supported_mechs[i]->name != NULL) {
	72	if (GSS_ERROR(gss_test_oid_set_member(&min_status,
	73	&supported_mechs[i]->oid, supported, &present)))
	74	present = 0;
	75	if (present)
	76	gss_add_oid_set_member(&min_status,
	77	&supported_mechs[i]->oid, oidset);
	78	i++;
	79	}
7cd30d48	80
7cd30d48	81	gss_release_oid_set(&min_status, &supported);
7364bd04	82	}
	83
	84
	85	/* Wrapper around accept_sec_context
	86	* Requires that the context contains:
	87	* oid
	88	* credentials (from ssh_gssapi_acquire_cred)
	89	*/
6e902aec	90	/* Privileged */
7364bd04	91	OM_uint32
	92	ssh_gssapi_accept_ctx(Gssctxt ctx, gss_buffer_desc recv_tok,
	93	gss_buffer_desc send_tok, OM_uint32 flags)
	94	{
	95	OM_uint32 status;
	96	gss_OID mech;
	97
	98	ctx->major = gss_accept_sec_context(&ctx->minor,
	99	&ctx->context, ctx->creds, recv_tok,
	100	GSS_C_NO_CHANNEL_BINDINGS, &ctx->client, &mech,
	101	send_tok, flags, NULL, &ctx->client_creds);
	102
	103	if (GSS_ERROR(ctx->major))
	104	ssh_gssapi_error(ctx);
	105
	106	if (ctx->client_creds)
	107	debug("Received some client credentials");
	108	else
	109	debug("Got no client credentials");
	110
	111	status = ctx->major;
	112
	113	/* Now, if we're complete and we have the right flags, then
	114	* we flag the user as also having been authenticated
	115	*/
	116
	117	if (((flags == NULL) \|\| ((*flags & GSS_C_MUTUAL_FLAG) &&
	118	(*flags & GSS_C_INTEG_FLAG))) && (ctx->major == GSS_S_COMPLETE)) {
	119	if (ssh_gssapi_getclient(ctx, &gssapi_client))
	120	fatal("Couldn't convert client name");
	121	}
	122
	123	return (status);
	124	}
	125
	126	/*
	127	* This parses an exported name, extracting the mechanism specific portion
	128	* to use for ACL checking. It verifies that the name belongs the mechanism
	129	* originally selected.
	130	*/
	131	static OM_uint32
	132	ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name)
	133	{
2ceb8101	134	u_char *tok;
7364bd04	135	OM_uint32 offset;
7364bd04	136	OM_uint32 oidl;
a7958e7b	137
8442cc66	138	tok = ename->value;
a7958e7b	139
	140	/*
	141	* Check that ename is long enough for all of the fixed length
7364bd04	142	* header, and that the initial ID bytes are correct
	143	*/
	144
8442cc66	145	if (ename->length < 6 \|\| memcmp(tok, "\x04\x01", 2) != 0)
7364bd04	146	return GSS_S_FAILURE;
	147
	148	/*
	149	* Extract the OID, and check it. Here GSSAPI breaks with tradition
	150	* and does use the OID type and length bytes. To confuse things
	151	* there are two lengths - the first including these, and the
	152	* second without.
	153	*/
	154
51e7a012	155	oidl = get_u16(tok+2); /* length including next two bytes */
7364bd04	156	oidl = oidl-2; /* turn it into the _real_ length of the variable OID */
	157
	158	/*
	159	* Check the BER encoding for correct type and length, that the
	160	* string is long enough and that the OID matches that in our context
	161	*/
	162	if (tok[4] != 0x06 \|\| tok[5] != oidl \|\|
a7958e7b	163	ename->length < oidl+6 \|\|
8442cc66	164	!ssh_gssapi_check_oid(ctx, tok+6, oidl))
7364bd04	165	return GSS_S_FAILURE;
	166
	167	offset = oidl+6;
a7958e7b	168
7364bd04	169	if (ename->length < offset+4)
7364bd04	170	return GSS_S_FAILURE;
a7958e7b	171
51e7a012	172	name->length = get_u32(tok+offset);
7364bd04	173	offset += 4;
a7958e7b	174
7364bd04	175	if (ename->length < offset+name->length)
a7958e7b	176	return GSS_S_FAILURE;
a7958e7b	177
96573c26	178	name->value = xmalloc(name->length+1);
1720c23b	179	memcpy(name->value, tok+offset, name->length);
96573c26	180	((char *)name->value)[name->length] = 0;
96573c26	181
7364bd04	182	return GSS_S_COMPLETE;
a7958e7b	183	}
7364bd04	184
	185	/* Extract the client details from a given context. This can only reliably
	186	* be called once for a context */
	187
6e902aec	188	/* Privileged (called from accept_secure_ctx) */
7364bd04	189	OM_uint32
	190	ssh_gssapi_getclient(Gssctxt ctx, ssh_gssapi_client client)
	191	{
	192	int i = 0;
	193
	194	gss_buffer_desc ename;
a7958e7b	195
7364bd04	196	client->mech = NULL;
	197
	198	while (supported_mechs[i]->name != NULL) {
	199	if (supported_mechs[i]->oid.length == ctx->oid->length &&
	200	(memcmp(supported_mechs[i]->oid.elements,
	201	ctx->oid->elements, ctx->oid->length) == 0))
	202	client->mech = supported_mechs[i];
	203	i++;
	204	}
	205
a7958e7b	206	if (client->mech == NULL)
7364bd04	207	return GSS_S_FAILURE;
a7958e7b	208
a7958e7b	209	if ((ctx->major = gss_display_name(&ctx->minor, ctx->client,
7364bd04	210	&client->displayname, NULL))) {
a7958e7b	211	ssh_gssapi_error(ctx);
a7958e7b	212	return (ctx->major);
7364bd04	213	}
a7958e7b	214
a7958e7b	215	if ((ctx->major = gss_export_name(&ctx->minor, ctx->client,
7364bd04	216	&ename))) {
	217	ssh_gssapi_error(ctx);
	218	return (ctx->major);
	219	}
a7958e7b	220
7364bd04	221	if ((ctx->major = ssh_gssapi_parse_ename(ctx,&ename,
	222	&client->exportedname))) {
	223	return (ctx->major);
	224	}
	225
	226	/* We can't copy this structure, so we just move the pointer to it */
	227	client->creds = ctx->client_creds;
	228	ctx->client_creds = GSS_C_NO_CREDENTIAL;
	229	return (ctx->major);
	230	}
	231
2362db19	232	/* As user - called on fatal/exit */
7364bd04	233	void
2362db19	234	ssh_gssapi_cleanup_creds(void)
7364bd04	235	{
	236	if (gssapi_client.store.filename != NULL) {
	237	/* Unlink probably isn't sufficient */
1720c23b	238	debug("removing gssapi cred file\"%s\"",
1720c23b	239	gssapi_client.store.filename);
7364bd04	240	unlink(gssapi_client.store.filename);
	241	}
	242	}
	243
	244	/* As user */
	245	void
	246	ssh_gssapi_storecreds(void)
	247	{
	248	if (gssapi_client.mech && gssapi_client.mech->storecreds) {
	249	(*gssapi_client.mech->storecreds)(&gssapi_client);
7364bd04	250	} else
	251	debug("ssh_gssapi_storecreds: Not a GSSAPI mechanism");
	252	}
	253
	254	/* This allows GSSAPI methods to do things to the childs environment based
	255	* on the passed authentication process and credentials.
	256	*/
	257	/* As user */
	258	void
	259	ssh_gssapi_do_child(char **envp, u_int envsizep)
	260	{
	261
	262	if (gssapi_client.store.envvar != NULL &&
	263	gssapi_client.store.envval != NULL) {
7364bd04	264	debug("Setting %s to %s", gssapi_client.store.envvar,
8442cc66	265	gssapi_client.store.envval);
7364bd04	266	child_set_env(envp, envsizep, gssapi_client.store.envvar,
4e2e5cfd	267	gssapi_client.store.envval);
7364bd04	268	}
	269	}
	270
67003554	271	/* Privileged */
7364bd04	272	int
	273	ssh_gssapi_userok(char *user)
	274	{
fe206de9	275	OM_uint32 lmin;
fe206de9	276
7364bd04	277	if (gssapi_client.exportedname.length == 0 \|\|
	278	gssapi_client.exportedname.value == NULL) {
	279	debug("No suitable client data");
	280	return 0;
	281	}
	282	if (gssapi_client.mech && gssapi_client.mech->userok)
fe206de9	283	if ((*gssapi_client.mech->userok)(&gssapi_client, user))
	284	return 1;
	285	else {
	286	/* Destroy delegated credentials if userok fails */
	287	gss_release_buffer(&lmin, &gssapi_client.displayname);
	288	gss_release_buffer(&lmin, &gssapi_client.exportedname);
	289	gss_release_cred(&lmin, &gssapi_client.creds);
	290	memset(&gssapi_client, 0, sizeof(ssh_gssapi_client));
	291	return 0;
	292	}
7364bd04	293	else
	294	debug("ssh_gssapi_userok: Unknown GSSAPI mechanism");
	295	return (0);
	296	}
	297
6e902aec	298	/* Privileged */
0789992b	299	OM_uint32
	300	ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic)
	301	{
	302	ctx->major = gss_verify_mic(&ctx->minor, ctx->context,
	303	gssbuf, gssmic, NULL);
	304
	305	return (ctx->major);
	306	}
	307
7364bd04	308	#endif