[gssapi-openssh.git] / openssh / gss-serv.c

/* $OpenBSD: gss-serv.c,v 1.22 2008/05/08 12:02:23 djm Exp $ */

/*
 * Copyright (c) 2001-2009 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 <sys/param.h>

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

#include "openbsd-compat/sys-queue.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 "servconf.h"
#include "uidswap.h"

#include "ssh-gss.h"
#include "monitor_wrap.h"

extern ServerOptions options;

static ssh_gssapi_client gssapi_client =
    { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER,
    GSS_C_NO_CREDENTIAL, GSS_C_NO_NAME,  NULL, {NULL, NULL, NULL}, 0, 0};

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


/*
 * Acquire credentials for a server running on the current host.
 * Requires that the context structure contains a valid OID
 */

/* Returns a GSSAPI error code */
/* Privileged (called from ssh_gssapi_server_ctx) */
static OM_uint32
ssh_gssapi_acquire_cred(Gssctxt *ctx)
{
	OM_uint32 status;
	char lname[MAXHOSTNAMELEN];
	gss_OID_set oidset;

	if (options.gss_strict_acceptor) {
		gss_create_empty_oid_set(&status, &oidset);
		gss_add_oid_set_member(&status, ctx->oid, &oidset);

		if (gethostname(lname, MAXHOSTNAMELEN)) {
			gss_release_oid_set(&status, &oidset);
			return (-1);
		}

		if (GSS_ERROR(ssh_gssapi_import_name(ctx, lname))) {
			gss_release_oid_set(&status, &oidset);
			return (ctx->major);
		}

		if ((ctx->major = gss_acquire_cred(&ctx->minor,
		    ctx->name, 0, oidset, GSS_C_ACCEPT, &ctx->creds, 
		    NULL, NULL)))
			ssh_gssapi_error(ctx);

		gss_release_oid_set(&status, &oidset);
		return (ctx->major);
	} else {
		ctx->name = GSS_C_NO_NAME;
		ctx->creds = GSS_C_NO_CREDENTIAL;
	}
	return GSS_S_COMPLETE;
}

/* Privileged */
OM_uint32
ssh_gssapi_server_ctx(Gssctxt **ctx, gss_OID oid)
{
	if (*ctx)
		ssh_gssapi_delete_ctx(ctx);
	ssh_gssapi_build_ctx(ctx);
	ssh_gssapi_set_oid(*ctx, oid);
	return (ssh_gssapi_acquire_cred(*ctx));
}

/* Unprivileged */
char *
ssh_gssapi_server_mechanisms() {
	gss_OID_set	supported;

	ssh_gssapi_supported_oids(&supported);
	return (ssh_gssapi_kex_mechs(supported, &ssh_gssapi_server_check_mech,
	    NULL, NULL));
}

/* Unprivileged */
int
ssh_gssapi_server_check_mech(Gssctxt **dum, gss_OID oid, const char *data,
    const char *dummy) {
	Gssctxt *ctx = NULL;
	int res;
 
	res = !GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctx, oid)));
	ssh_gssapi_delete_ctx(&ctx);

	return (res);
}

/* 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);

	if (GSS_ERROR(gss_indicate_mechs(&min_status, &supported)))
		return;

	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;
	int equal = 0;
	gss_name_t new_name = GSS_C_NO_NAME;
	gss_buffer_desc ename = GSS_C_EMPTY_BUFFER;

	if (options.gss_store_rekey && client->used && ctx->client_creds) {
		if (client->mech->oid.length != ctx->oid->length ||
		    (memcmp(client->mech->oid.elements,
		     ctx->oid->elements, ctx->oid->length) !=0)) {
			debug("Rekeyed credentials have different mechanism");
			return GSS_S_COMPLETE;
		}

		if ((ctx->major = gss_inquire_cred_by_mech(&ctx->minor, 
		    ctx->client_creds, ctx->oid, &new_name, 
		    NULL, NULL, NULL))) {
			ssh_gssapi_error(ctx);
			return (ctx->major);
		}

		ctx->major = gss_compare_name(&ctx->minor, client->name, 
		    new_name, &equal);

		if (GSS_ERROR(ctx->major)) {
			ssh_gssapi_error(ctx);
			return (ctx->major);
		}
 
		if (!equal) {
			debug("Rekeyed credentials have different name");
			return GSS_S_COMPLETE;
		}

		debug("Marking rekeyed credentials for export");

		gss_release_name(&ctx->minor, &client->name);
		gss_release_cred(&ctx->minor, &client->creds);
		client->name = new_name;
		client->creds = ctx->client_creds;
        	ctx->client_creds = GSS_C_NO_CREDENTIAL;
		client->updated = 1;
		return GSS_S_COMPLETE;
	}

	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->client_creds &&
	    (ctx->major = gss_inquire_cred_by_mech(&ctx->minor,
	     ctx->client_creds, ctx->oid, &client->name, NULL, NULL, NULL))) {
		ssh_gssapi_error(ctx);
		return (ctx->major);
	}

	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);
	}

	gss_release_buffer(&ctx->minor, &ename);

	/* 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, struct passwd *pw)
{
	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)) {
			gssapi_client.used = 1;
			gssapi_client.store.owner = pw;
			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);
}

/* These bits are only used for rekeying. The unpriviledged child is running 
 * as the user, the monitor is root.
 *
 * In the child, we want to :
 *    *) Ask the monitor to store our credentials into the store we specify
 *    *) If it succeeds, maybe do a PAM update
 */

/* Stuff for PAM */

#ifdef USE_PAM
static int ssh_gssapi_simple_conv(int n, const struct pam_message **msg, 
    struct pam_response **resp, void *data)
{
	return (PAM_CONV_ERR);
}
#endif

void
ssh_gssapi_rekey_creds() {
	int ok;
	int ret;
#ifdef USE_PAM
	pam_handle_t *pamh = NULL;
	struct pam_conv pamconv = {ssh_gssapi_simple_conv, NULL};
	char *envstr;
#endif

	if (gssapi_client.store.filename == NULL && 
	    gssapi_client.store.envval == NULL &&
	    gssapi_client.store.envvar == NULL)
		return;
 
	ok = PRIVSEP(ssh_gssapi_update_creds(&gssapi_client.store));

	if (!ok)
		return;

	debug("Rekeyed credentials stored successfully");

	/* Actually managing to play with the ssh pam stack from here will
	 * be next to impossible. In any case, we may want different options
	 * for rekeying. So, use our own :)
	 */
#ifdef USE_PAM	
	if (!use_privsep) {
		debug("Not even going to try and do PAM with privsep disabled");
		return;
	}

	ret = pam_start("sshd-rekey", gssapi_client.store.owner->pw_name,
 	    &pamconv, &pamh);
	if (ret)
		return;

	xasprintf(&envstr, "%s=%s", gssapi_client.store.envvar, 
	    gssapi_client.store.envval);

	ret = pam_putenv(pamh, envstr);
	if (!ret)
		pam_setcred(pamh, PAM_REINITIALIZE_CRED);
	pam_end(pamh, PAM_SUCCESS);
#endif
}

int 
ssh_gssapi_update_creds(ssh_gssapi_ccache *store) {
	int ok = 0;

	/* Check we've got credentials to store */
	if (!gssapi_client.updated)
		return 0;

	gssapi_client.updated = 0;

	temporarily_use_uid(gssapi_client.store.owner);
	if (gssapi_client.mech && gssapi_client.mech->updatecreds)
		ok = (*gssapi_client.mech->updatecreds)(store, &gssapi_client);
	else
		debug("No update function for this mechanism");

	restore_uid();

	return ok;
}

#endif
Commit	Line	Data
22616013	1	/* $OpenBSD: gss-serv.c,v 1.22 2008/05/08 12:02:23 djm Exp $ */
0fff78ff	2
0fff78ff	3	/*
f97edba6	4	* Copyright (c) 2001-2009 Simon Wilkinson. All rights reserved.
0fff78ff	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
9108f8d9	31	#include <sys/types.h>
d4487008	32	#include <sys/param.h>
9108f8d9	33
	34	#include <stdarg.h>
	35	#include <string.h>
	36	#include <unistd.h>
	37
22616013	38	#include "openbsd-compat/sys-queue.h"
9108f8d9	39	#include "xmalloc.h"
	40	#include "buffer.h"
	41	#include "key.h"
	42	#include "hostfile.h"
0fff78ff	43	#include "auth.h"
	44	#include "log.h"
	45	#include "channels.h"
	46	#include "session.h"
9108f8d9	47	#include "misc.h"
f97edba6	48	#include "servconf.h"
f97edba6	49	#include "uidswap.h"
0fff78ff	50
0fff78ff	51	#include "ssh-gss.h"
f97edba6	52	#include "monitor_wrap.h"
	53
	54	extern ServerOptions options;
0fff78ff	55
0fff78ff	56	static ssh_gssapi_client gssapi_client =
0fff78ff	57	{ GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER,
f97edba6	58	GSS_C_NO_CREDENTIAL, GSS_C_NO_NAME, NULL, {NULL, NULL, NULL}, 0, 0};
0fff78ff	59
0fff78ff	60	ssh_gssapi_mech gssapi_null_mech =
f97edba6	61	{ NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL, NULL};
0fff78ff	62
	63	#ifdef KRB5
	64	extern ssh_gssapi_mech gssapi_kerberos_mech;
	65	#endif
	66
	67	ssh_gssapi_mech* supported_mechs[]= {
	68	#ifdef KRB5
	69	&gssapi_kerberos_mech,
	70	#endif
	71	&gssapi_null_mech,
	72	};
	73
d4487008	74
	75	/*
	76	* Acquire credentials for a server running on the current host.
	77	* Requires that the context structure contains a valid OID
	78	*/
	79
	80	/* Returns a GSSAPI error code */
	81	/* Privileged (called from ssh_gssapi_server_ctx) */
	82	static OM_uint32
	83	ssh_gssapi_acquire_cred(Gssctxt *ctx)
	84	{
	85	OM_uint32 status;
	86	char lname[MAXHOSTNAMELEN];
	87	gss_OID_set oidset;
	88
f97edba6	89	if (options.gss_strict_acceptor) {
	90	gss_create_empty_oid_set(&status, &oidset);
	91	gss_add_oid_set_member(&status, ctx->oid, &oidset);
d4487008	92
f97edba6	93	if (gethostname(lname, MAXHOSTNAMELEN)) {
	94	gss_release_oid_set(&status, &oidset);
	95	return (-1);
	96	}
	97
	98	if (GSS_ERROR(ssh_gssapi_import_name(ctx, lname))) {
	99	gss_release_oid_set(&status, &oidset);
	100	return (ctx->major);
	101	}
	102
	103	if ((ctx->major = gss_acquire_cred(&ctx->minor,
	104	ctx->name, 0, oidset, GSS_C_ACCEPT, &ctx->creds,
	105	NULL, NULL)))
	106	ssh_gssapi_error(ctx);
d4487008	107
d4487008	108	gss_release_oid_set(&status, &oidset);
d4487008	109	return (ctx->major);
f97edba6	110	} else {
	111	ctx->name = GSS_C_NO_NAME;
	112	ctx->creds = GSS_C_NO_CREDENTIAL;
d4487008	113	}
f97edba6	114	return GSS_S_COMPLETE;
d4487008	115	}
	116
	117	/* Privileged */
	118	OM_uint32
	119	ssh_gssapi_server_ctx(Gssctxt **ctx, gss_OID oid)
	120	{
	121	if (*ctx)
	122	ssh_gssapi_delete_ctx(ctx);
	123	ssh_gssapi_build_ctx(ctx);
	124	ssh_gssapi_set_oid(*ctx, oid);
	125	return (ssh_gssapi_acquire_cred(*ctx));
	126	}
	127
f97edba6	128	/* Unprivileged */
	129	char *
	130	ssh_gssapi_server_mechanisms() {
	131	gss_OID_set supported;
	132
	133	ssh_gssapi_supported_oids(&supported);
	134	return (ssh_gssapi_kex_mechs(supported, &ssh_gssapi_server_check_mech,
	135	NULL, NULL));
	136	}
	137
	138	/* Unprivileged */
	139	int
	140	ssh_gssapi_server_check_mech(Gssctxt *dum, gss_OID oid, const char data,
	141	const char *dummy) {
	142	Gssctxt *ctx = NULL;
	143	int res;
	144
	145	res = !GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctx, oid)));
	146	ssh_gssapi_delete_ctx(&ctx);
	147
	148	return (res);
	149	}
	150
2c06c99b	151	/* Unprivileged */
0fff78ff	152	void
	153	ssh_gssapi_supported_oids(gss_OID_set *oidset)
	154	{
	155	int i = 0;
	156	OM_uint32 min_status;
	157	int present;
	158	gss_OID_set supported;
	159
	160	gss_create_empty_oid_set(&min_status, oidset);
f97edba6	161
	162	if (GSS_ERROR(gss_indicate_mechs(&min_status, &supported)))
	163	return;
0fff78ff	164
	165	while (supported_mechs[i]->name != NULL) {
	166	if (GSS_ERROR(gss_test_oid_set_member(&min_status,
	167	&supported_mechs[i]->oid, supported, &present)))
	168	present = 0;
	169	if (present)
	170	gss_add_oid_set_member(&min_status,
	171	&supported_mechs[i]->oid, oidset);
	172	i++;
	173	}
9108f8d9	174
9108f8d9	175	gss_release_oid_set(&min_status, &supported);
0fff78ff	176	}
	177
	178
	179	/* Wrapper around accept_sec_context
	180	* Requires that the context contains:
	181	* oid
	182	* credentials (from ssh_gssapi_acquire_cred)
	183	*/
2c06c99b	184	/* Privileged */
0fff78ff	185	OM_uint32
	186	ssh_gssapi_accept_ctx(Gssctxt ctx, gss_buffer_desc recv_tok,
	187	gss_buffer_desc send_tok, OM_uint32 flags)
	188	{
	189	OM_uint32 status;
	190	gss_OID mech;
	191
	192	ctx->major = gss_accept_sec_context(&ctx->minor,
	193	&ctx->context, ctx->creds, recv_tok,
	194	GSS_C_NO_CHANNEL_BINDINGS, &ctx->client, &mech,
	195	send_tok, flags, NULL, &ctx->client_creds);
	196
	197	if (GSS_ERROR(ctx->major))
	198	ssh_gssapi_error(ctx);
	199
	200	if (ctx->client_creds)
	201	debug("Received some client credentials");
	202	else
	203	debug("Got no client credentials");
	204
	205	status = ctx->major;
	206
	207	/* Now, if we're complete and we have the right flags, then
	208	* we flag the user as also having been authenticated
	209	*/
	210
	211	if (((flags == NULL) \|\| ((*flags & GSS_C_MUTUAL_FLAG) &&
	212	(*flags & GSS_C_INTEG_FLAG))) && (ctx->major == GSS_S_COMPLETE)) {
	213	if (ssh_gssapi_getclient(ctx, &gssapi_client))
	214	fatal("Couldn't convert client name");
	215	}
	216
	217	return (status);
	218	}
	219
	220	/*
	221	* This parses an exported name, extracting the mechanism specific portion
	222	* to use for ACL checking. It verifies that the name belongs the mechanism
	223	* originally selected.
	224	*/
	225	static OM_uint32
	226	ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name)
	227	{
665a873d	228	u_char *tok;
0fff78ff	229	OM_uint32 offset;
	230	OM_uint32 oidl;
	231
2c06c99b	232	tok = ename->value;
0fff78ff	233
	234	/*
	235	* Check that ename is long enough for all of the fixed length
	236	* header, and that the initial ID bytes are correct
	237	*/
	238
2c06c99b	239	if (ename->length < 6 \|\| memcmp(tok, "\x04\x01", 2) != 0)
0fff78ff	240	return GSS_S_FAILURE;
	241
	242	/*
	243	* Extract the OID, and check it. Here GSSAPI breaks with tradition
	244	* and does use the OID type and length bytes. To confuse things
	245	* there are two lengths - the first including these, and the
	246	* second without.
	247	*/
	248
9108f8d9	249	oidl = get_u16(tok+2); /* length including next two bytes */
0fff78ff	250	oidl = oidl-2; /* turn it into the _real_ length of the variable OID */
	251
	252	/*
	253	* Check the BER encoding for correct type and length, that the
	254	* string is long enough and that the OID matches that in our context
	255	*/
	256	if (tok[4] != 0x06 \|\| tok[5] != oidl \|\|
	257	ename->length < oidl+6 \|\|
2c06c99b	258	!ssh_gssapi_check_oid(ctx, tok+6, oidl))
0fff78ff	259	return GSS_S_FAILURE;
	260
	261	offset = oidl+6;
	262
	263	if (ename->length < offset+4)
	264	return GSS_S_FAILURE;
	265
9108f8d9	266	name->length = get_u32(tok+offset);
0fff78ff	267	offset += 4;
	268
	269	if (ename->length < offset+name->length)
	270	return GSS_S_FAILURE;
	271
	272	name->value = xmalloc(name->length+1);
9108f8d9	273	memcpy(name->value, tok+offset, name->length);
0fff78ff	274	((char *)name->value)[name->length] = 0;
	275
	276	return GSS_S_COMPLETE;
	277	}
	278
	279	/* Extract the client details from a given context. This can only reliably
	280	* be called once for a context */
	281
2c06c99b	282	/* Privileged (called from accept_secure_ctx) */
0fff78ff	283	OM_uint32
	284	ssh_gssapi_getclient(Gssctxt ctx, ssh_gssapi_client client)
	285	{
	286	int i = 0;
f97edba6	287	int equal = 0;
	288	gss_name_t new_name = GSS_C_NO_NAME;
	289	gss_buffer_desc ename = GSS_C_EMPTY_BUFFER;
	290
	291	if (options.gss_store_rekey && client->used && ctx->client_creds) {
	292	if (client->mech->oid.length != ctx->oid->length \|\|
	293	(memcmp(client->mech->oid.elements,
	294	ctx->oid->elements, ctx->oid->length) !=0)) {
	295	debug("Rekeyed credentials have different mechanism");
	296	return GSS_S_COMPLETE;
	297	}
	298
	299	if ((ctx->major = gss_inquire_cred_by_mech(&ctx->minor,
	300	ctx->client_creds, ctx->oid, &new_name,
	301	NULL, NULL, NULL))) {
	302	ssh_gssapi_error(ctx);
	303	return (ctx->major);
	304	}
	305
	306	ctx->major = gss_compare_name(&ctx->minor, client->name,
	307	new_name, &equal);
0fff78ff	308
f97edba6	309	if (GSS_ERROR(ctx->major)) {
	310	ssh_gssapi_error(ctx);
	311	return (ctx->major);
	312	}
	313
	314	if (!equal) {
	315	debug("Rekeyed credentials have different name");
	316	return GSS_S_COMPLETE;
	317	}
	318
	319	debug("Marking rekeyed credentials for export");
	320
	321	gss_release_name(&ctx->minor, &client->name);
	322	gss_release_cred(&ctx->minor, &client->creds);
	323	client->name = new_name;
	324	client->creds = ctx->client_creds;
	325	ctx->client_creds = GSS_C_NO_CREDENTIAL;
	326	client->updated = 1;
	327	return GSS_S_COMPLETE;
	328	}
0fff78ff	329
	330	client->mech = NULL;
	331
	332	while (supported_mechs[i]->name != NULL) {
	333	if (supported_mechs[i]->oid.length == ctx->oid->length &&
	334	(memcmp(supported_mechs[i]->oid.elements,
	335	ctx->oid->elements, ctx->oid->length) == 0))
	336	client->mech = supported_mechs[i];
	337	i++;
	338	}
	339
	340	if (client->mech == NULL)
	341	return GSS_S_FAILURE;
	342
f97edba6	343	if (ctx->client_creds &&
	344	(ctx->major = gss_inquire_cred_by_mech(&ctx->minor,
	345	ctx->client_creds, ctx->oid, &client->name, NULL, NULL, NULL))) {
	346	ssh_gssapi_error(ctx);
	347	return (ctx->major);
	348	}
	349
0fff78ff	350	if ((ctx->major = gss_display_name(&ctx->minor, ctx->client,
	351	&client->displayname, NULL))) {
	352	ssh_gssapi_error(ctx);
	353	return (ctx->major);
	354	}
	355
	356	if ((ctx->major = gss_export_name(&ctx->minor, ctx->client,
	357	&ename))) {
	358	ssh_gssapi_error(ctx);
	359	return (ctx->major);
	360	}
	361
	362	if ((ctx->major = ssh_gssapi_parse_ename(ctx,&ename,
	363	&client->exportedname))) {
	364	return (ctx->major);
	365	}
	366
f97edba6	367	gss_release_buffer(&ctx->minor, &ename);
f97edba6	368
0fff78ff	369	/* We can't copy this structure, so we just move the pointer to it */
	370	client->creds = ctx->client_creds;
	371	ctx->client_creds = GSS_C_NO_CREDENTIAL;
	372	return (ctx->major);
	373	}
	374
cdd66111	375	/* As user - called on fatal/exit */
0fff78ff	376	void
cdd66111	377	ssh_gssapi_cleanup_creds(void)
0fff78ff	378	{
	379	if (gssapi_client.store.filename != NULL) {
	380	/* Unlink probably isn't sufficient */
9108f8d9	381	debug("removing gssapi cred file\"%s\"",
9108f8d9	382	gssapi_client.store.filename);
0fff78ff	383	unlink(gssapi_client.store.filename);
	384	}
	385	}
	386
	387	/* As user */
	388	void
	389	ssh_gssapi_storecreds(void)
	390	{
	391	if (gssapi_client.mech && gssapi_client.mech->storecreds) {
	392	(*gssapi_client.mech->storecreds)(&gssapi_client);
0fff78ff	393	} else
	394	debug("ssh_gssapi_storecreds: Not a GSSAPI mechanism");
	395	}
	396
	397	/* This allows GSSAPI methods to do things to the childs environment based
	398	* on the passed authentication process and credentials.
	399	*/
	400	/* As user */
	401	void
	402	ssh_gssapi_do_child(char **envp, u_int envsizep)
	403	{
	404
	405	if (gssapi_client.store.envvar != NULL &&
	406	gssapi_client.store.envval != NULL) {
0fff78ff	407	debug("Setting %s to %s", gssapi_client.store.envvar,
2c06c99b	408	gssapi_client.store.envval);
0fff78ff	409	child_set_env(envp, envsizep, gssapi_client.store.envvar,
665a873d	410	gssapi_client.store.envval);
0fff78ff	411	}
	412	}
	413
2c06c99b	414	/* Privileged */
0fff78ff	415	int
f97edba6	416	ssh_gssapi_userok(char user, struct passwd pw)
0fff78ff	417	{
665a873d	418	OM_uint32 lmin;
665a873d	419
0fff78ff	420	if (gssapi_client.exportedname.length == 0 \|\|
	421	gssapi_client.exportedname.value == NULL) {
	422	debug("No suitable client data");
	423	return 0;
	424	}
	425	if (gssapi_client.mech && gssapi_client.mech->userok)
f97edba6	426	if ((*gssapi_client.mech->userok)(&gssapi_client, user)) {
	427	gssapi_client.used = 1;
	428	gssapi_client.store.owner = pw;
665a873d	429	return 1;
f97edba6	430	} else {
665a873d	431	/* Destroy delegated credentials if userok fails */
	432	gss_release_buffer(&lmin, &gssapi_client.displayname);
	433	gss_release_buffer(&lmin, &gssapi_client.exportedname);
	434	gss_release_cred(&lmin, &gssapi_client.creds);
	435	memset(&gssapi_client, 0, sizeof(ssh_gssapi_client));
	436	return 0;
	437	}
0fff78ff	438	else
	439	debug("ssh_gssapi_userok: Unknown GSSAPI mechanism");
	440	return (0);
	441	}
	442
f97edba6	443	/* These bits are only used for rekeying. The unpriviledged child is running
	444	* as the user, the monitor is root.
	445	*
	446	* In the child, we want to :
	447	* *) Ask the monitor to store our credentials into the store we specify
	448	* *) If it succeeds, maybe do a PAM update
	449	*/
	450
	451	/* Stuff for PAM */
	452
	453	#ifdef USE_PAM
	454	static int ssh_gssapi_simple_conv(int n, const struct pam_message **msg,
	455	struct pam_response *resp, void data)
cdd66111	456	{
f97edba6	457	return (PAM_CONV_ERR);
	458	}
	459	#endif
cdd66111	460
f97edba6	461	void
	462	ssh_gssapi_rekey_creds() {
	463	int ok;
	464	int ret;
	465	#ifdef USE_PAM
	466	pam_handle_t *pamh = NULL;
	467	struct pam_conv pamconv = {ssh_gssapi_simple_conv, NULL};
	468	char *envstr;
	469	#endif
	470
	471	if (gssapi_client.store.filename == NULL &&
	472	gssapi_client.store.envval == NULL &&
	473	gssapi_client.store.envvar == NULL)
	474	return;
	475
	476	ok = PRIVSEP(ssh_gssapi_update_creds(&gssapi_client.store));
	477
	478	if (!ok)
	479	return;
	480
	481	debug("Rekeyed credentials stored successfully");
	482
	483	/* Actually managing to play with the ssh pam stack from here will
	484	* be next to impossible. In any case, we may want different options
	485	* for rekeying. So, use our own :)
	486	*/
	487	#ifdef USE_PAM
	488	if (!use_privsep) {
	489	debug("Not even going to try and do PAM with privsep disabled");
	490	return;
	491	}
	492
	493	ret = pam_start("sshd-rekey", gssapi_client.store.owner->pw_name,
	494	&pamconv, &pamh);
	495	if (ret)
	496	return;
	497
	498	xasprintf(&envstr, "%s=%s", gssapi_client.store.envvar,
	499	gssapi_client.store.envval);
	500
	501	ret = pam_putenv(pamh, envstr);
	502	if (!ret)
	503	pam_setcred(pamh, PAM_REINITIALIZE_CRED);
	504	pam_end(pamh, PAM_SUCCESS);
	505	#endif
	506	}
	507
	508	int
	509	ssh_gssapi_update_creds(ssh_gssapi_ccache *store) {
	510	int ok = 0;
	511
	512	/* Check we've got credentials to store */
	513	if (!gssapi_client.updated)
	514	return 0;
	515
	516	gssapi_client.updated = 0;
	517
	518	temporarily_use_uid(gssapi_client.store.owner);
	519	if (gssapi_client.mech && gssapi_client.mech->updatecreds)
	520	ok = (*gssapi_client.mech->updatecreds)(store, &gssapi_client);
	521	else
	522	debug("No update function for this mechanism");
	523
	524	restore_uid();
525
526	return ok;
cdd66111	527	}
cdd66111	528
0fff78ff	529	#endif