[openssh.git] / gss-serv.c

/* $OpenBSD: gss-serv.c,v 1.20 2006/08/03 03:34:42 deraadt 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 <sys/types.h>

#include <stdarg.h>
#include <string.h>
#include <unistd.h>

#include "xmalloc.h"
#include "buffer.h"
#include "key.h"
#include "hostfile.h"
#include "auth.h"
#include "log.h"
#include "channels.h"
#include "session.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
31652869	1	/* $OpenBSD: gss-serv.c,v 1.20 2006/08/03 03:34:42 deraadt 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
31652869	31	#include <sys/types.h>
31652869	32
24436b92	33	#include <stdarg.h>
00146caa	34	#include <string.h>
28cb0a43	35	#include <unistd.h>
00146caa	36
31652869	37	#include "xmalloc.h"
	38	#include "buffer.h"
	39	#include "key.h"
	40	#include "hostfile.h"
7364bd04	41	#include "auth.h"
	42	#include "log.h"
	43	#include "channels.h"
	44	#include "session.h"
51e7a012	45	#include "misc.h"
7364bd04	46
	47	#include "ssh-gss.h"
	48
7364bd04	49	static ssh_gssapi_client gssapi_client =
	50	{ GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER,
	51	GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL}};
	52
	53	ssh_gssapi_mech gssapi_null_mech =
	54	{ NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL};
	55
	56	#ifdef KRB5
	57	extern ssh_gssapi_mech gssapi_kerberos_mech;
	58	#endif
	59
	60	ssh_gssapi_mech* supported_mechs[]= {
	61	#ifdef KRB5
	62	&gssapi_kerberos_mech,
	63	#endif
	64	&gssapi_null_mech,
	65	};
	66
6e902aec	67	/* Unprivileged */
7364bd04	68	void
	69	ssh_gssapi_supported_oids(gss_OID_set *oidset)
	70	{
	71	int i = 0;
	72	OM_uint32 min_status;
	73	int present;
	74	gss_OID_set supported;
	75
	76	gss_create_empty_oid_set(&min_status, oidset);
	77	gss_indicate_mechs(&min_status, &supported);
	78
	79	while (supported_mechs[i]->name != NULL) {
	80	if (GSS_ERROR(gss_test_oid_set_member(&min_status,
	81	&supported_mechs[i]->oid, supported, &present)))
	82	present = 0;
	83	if (present)
	84	gss_add_oid_set_member(&min_status,
	85	&supported_mechs[i]->oid, oidset);
	86	i++;
	87	}
7cd30d48	88
7cd30d48	89	gss_release_oid_set(&min_status, &supported);
7364bd04	90	}
	91
	92
	93	/* Wrapper around accept_sec_context
	94	* Requires that the context contains:
	95	* oid
	96	* credentials (from ssh_gssapi_acquire_cred)
	97	*/
6e902aec	98	/* Privileged */
7364bd04	99	OM_uint32
	100	ssh_gssapi_accept_ctx(Gssctxt ctx, gss_buffer_desc recv_tok,
	101	gss_buffer_desc send_tok, OM_uint32 flags)
	102	{
	103	OM_uint32 status;
	104	gss_OID mech;
	105
	106	ctx->major = gss_accept_sec_context(&ctx->minor,
	107	&ctx->context, ctx->creds, recv_tok,
	108	GSS_C_NO_CHANNEL_BINDINGS, &ctx->client, &mech,
	109	send_tok, flags, NULL, &ctx->client_creds);
	110
	111	if (GSS_ERROR(ctx->major))
	112	ssh_gssapi_error(ctx);
	113
	114	if (ctx->client_creds)
	115	debug("Received some client credentials");
	116	else
	117	debug("Got no client credentials");
	118
	119	status = ctx->major;
	120
	121	/* Now, if we're complete and we have the right flags, then
	122	* we flag the user as also having been authenticated
	123	*/
	124
	125	if (((flags == NULL) \|\| ((*flags & GSS_C_MUTUAL_FLAG) &&
	126	(*flags & GSS_C_INTEG_FLAG))) && (ctx->major == GSS_S_COMPLETE)) {
	127	if (ssh_gssapi_getclient(ctx, &gssapi_client))
	128	fatal("Couldn't convert client name");
	129	}
	130
	131	return (status);
	132	}
	133
	134	/*
	135	* This parses an exported name, extracting the mechanism specific portion
	136	* to use for ACL checking. It verifies that the name belongs the mechanism
	137	* originally selected.
	138	*/
	139	static OM_uint32
	140	ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name)
	141	{
2ceb8101	142	u_char *tok;
7364bd04	143	OM_uint32 offset;
7364bd04	144	OM_uint32 oidl;
a7958e7b	145
8442cc66	146	tok = ename->value;
a7958e7b	147
	148	/*
	149	* Check that ename is long enough for all of the fixed length
7364bd04	150	* header, and that the initial ID bytes are correct
	151	*/
	152
8442cc66	153	if (ename->length < 6 \|\| memcmp(tok, "\x04\x01", 2) != 0)
7364bd04	154	return GSS_S_FAILURE;
	155
	156	/*
	157	* Extract the OID, and check it. Here GSSAPI breaks with tradition
	158	* and does use the OID type and length bytes. To confuse things
	159	* there are two lengths - the first including these, and the
	160	* second without.
	161	*/
	162
51e7a012	163	oidl = get_u16(tok+2); /* length including next two bytes */
7364bd04	164	oidl = oidl-2; /* turn it into the _real_ length of the variable OID */
	165
	166	/*
	167	* Check the BER encoding for correct type and length, that the
	168	* string is long enough and that the OID matches that in our context
	169	*/
	170	if (tok[4] != 0x06 \|\| tok[5] != oidl \|\|
a7958e7b	171	ename->length < oidl+6 \|\|
8442cc66	172	!ssh_gssapi_check_oid(ctx, tok+6, oidl))
7364bd04	173	return GSS_S_FAILURE;
	174
	175	offset = oidl+6;
a7958e7b	176
7364bd04	177	if (ename->length < offset+4)
7364bd04	178	return GSS_S_FAILURE;
a7958e7b	179
51e7a012	180	name->length = get_u32(tok+offset);
7364bd04	181	offset += 4;
a7958e7b	182
7364bd04	183	if (ename->length < offset+name->length)
a7958e7b	184	return GSS_S_FAILURE;
a7958e7b	185
96573c26	186	name->value = xmalloc(name->length+1);
1720c23b	187	memcpy(name->value, tok+offset, name->length);
96573c26	188	((char *)name->value)[name->length] = 0;
96573c26	189
7364bd04	190	return GSS_S_COMPLETE;
a7958e7b	191	}
7364bd04	192
	193	/* Extract the client details from a given context. This can only reliably
	194	* be called once for a context */
	195
6e902aec	196	/* Privileged (called from accept_secure_ctx) */
7364bd04	197	OM_uint32
	198	ssh_gssapi_getclient(Gssctxt ctx, ssh_gssapi_client client)
	199	{
	200	int i = 0;
	201
	202	gss_buffer_desc ename;
a7958e7b	203
7364bd04	204	client->mech = NULL;
	205
	206	while (supported_mechs[i]->name != NULL) {
	207	if (supported_mechs[i]->oid.length == ctx->oid->length &&
	208	(memcmp(supported_mechs[i]->oid.elements,
	209	ctx->oid->elements, ctx->oid->length) == 0))
	210	client->mech = supported_mechs[i];
	211	i++;
	212	}
	213
a7958e7b	214	if (client->mech == NULL)
7364bd04	215	return GSS_S_FAILURE;
a7958e7b	216
a7958e7b	217	if ((ctx->major = gss_display_name(&ctx->minor, ctx->client,
7364bd04	218	&client->displayname, NULL))) {
a7958e7b	219	ssh_gssapi_error(ctx);
a7958e7b	220	return (ctx->major);
7364bd04	221	}
a7958e7b	222
a7958e7b	223	if ((ctx->major = gss_export_name(&ctx->minor, ctx->client,
7364bd04	224	&ename))) {
	225	ssh_gssapi_error(ctx);
	226	return (ctx->major);
	227	}
a7958e7b	228
7364bd04	229	if ((ctx->major = ssh_gssapi_parse_ename(ctx,&ename,
	230	&client->exportedname))) {
	231	return (ctx->major);
	232	}
	233
	234	/* We can't copy this structure, so we just move the pointer to it */
	235	client->creds = ctx->client_creds;
	236	ctx->client_creds = GSS_C_NO_CREDENTIAL;
	237	return (ctx->major);
	238	}
	239
2362db19	240	/* As user - called on fatal/exit */
7364bd04	241	void
2362db19	242	ssh_gssapi_cleanup_creds(void)
7364bd04	243	{
	244	if (gssapi_client.store.filename != NULL) {
	245	/* Unlink probably isn't sufficient */
1720c23b	246	debug("removing gssapi cred file\"%s\"",
1720c23b	247	gssapi_client.store.filename);
7364bd04	248	unlink(gssapi_client.store.filename);
	249	}
	250	}
	251
	252	/* As user */
	253	void
	254	ssh_gssapi_storecreds(void)
	255	{
	256	if (gssapi_client.mech && gssapi_client.mech->storecreds) {
	257	(*gssapi_client.mech->storecreds)(&gssapi_client);
7364bd04	258	} else
	259	debug("ssh_gssapi_storecreds: Not a GSSAPI mechanism");
	260	}
	261
	262	/* This allows GSSAPI methods to do things to the childs environment based
	263	* on the passed authentication process and credentials.
	264	*/
	265	/* As user */
	266	void
	267	ssh_gssapi_do_child(char **envp, u_int envsizep)
	268	{
	269
	270	if (gssapi_client.store.envvar != NULL &&
	271	gssapi_client.store.envval != NULL) {
7364bd04	272	debug("Setting %s to %s", gssapi_client.store.envvar,
8442cc66	273	gssapi_client.store.envval);
7364bd04	274	child_set_env(envp, envsizep, gssapi_client.store.envvar,
4e2e5cfd	275	gssapi_client.store.envval);
7364bd04	276	}
	277	}
	278
67003554	279	/* Privileged */
7364bd04	280	int
	281	ssh_gssapi_userok(char *user)
	282	{
fe206de9	283	OM_uint32 lmin;
fe206de9	284
7364bd04	285	if (gssapi_client.exportedname.length == 0 \|\|
	286	gssapi_client.exportedname.value == NULL) {
	287	debug("No suitable client data");
	288	return 0;
	289	}
	290	if (gssapi_client.mech && gssapi_client.mech->userok)
fe206de9	291	if ((*gssapi_client.mech->userok)(&gssapi_client, user))
	292	return 1;
	293	else {
	294	/* Destroy delegated credentials if userok fails */
	295	gss_release_buffer(&lmin, &gssapi_client.displayname);
	296	gss_release_buffer(&lmin, &gssapi_client.exportedname);
	297	gss_release_cred(&lmin, &gssapi_client.creds);
	298	memset(&gssapi_client, 0, sizeof(ssh_gssapi_client));
	299	return 0;
	300	}
7364bd04	301	else
	302	debug("ssh_gssapi_userok: Unknown GSSAPI mechanism");
	303	return (0);
	304	}
	305
6e902aec	306	/* Privileged */
0789992b	307	OM_uint32
	308	ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic)
	309	{
	310	ctx->major = gss_verify_mic(&ctx->minor, ctx->context,
	311	gssbuf, gssmic, NULL);
	312
	313	return (ctx->major);
	314	}
	315
7364bd04	316	#endif