accept_sec_context.c

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/*
 * Copyright (c) 1997 - 2006 Kungliga Tekniska H鰃skolan
 * (Royal Institute of Technology, Stockholm, Sweden). 
 * Portions Copyright (c) 2004 PADL Software Pty Ltd.
 *
 * 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. 
 *
 * 3. Neither the name of the Institute nor the names of its contributors 
 *    may be used to endorse or promote products derived from this software 
 *    without specific prior written permission. 
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``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 INSTITUTE OR CONTRIBUTORS 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 "spnego/spnego_locl.h"

RCSID("$Id: accept_sec_context.c 22600 2008-02-21 12:46:24Z lha $");

static OM_uint32
send_reject (OM_uint32 *minor_status,
	     gss_buffer_t output_token)
{
    NegotiationToken nt;
    size_t size;

    nt.element = choice_NegotiationToken_negTokenResp;

    ALLOC(nt.u.negTokenResp.negResult, 1);
    if (nt.u.negTokenResp.negResult == NULL) {
	*minor_status = ENOMEM;
	return GSS_S_FAILURE;
    }
    *(nt.u.negTokenResp.negResult)  = reject;
    nt.u.negTokenResp.supportedMech = NULL;
    nt.u.negTokenResp.responseToken = NULL;
    nt.u.negTokenResp.mechListMIC   = NULL;
    
    ASN1_MALLOC_ENCODE(NegotiationToken,
		       output_token->value, output_token->length, &nt,
		       &size, *minor_status);
    free_NegotiationToken(&nt);
    if (*minor_status != 0)
	return GSS_S_FAILURE;

    return GSS_S_BAD_MECH;
}

static OM_uint32
acceptor_approved(gss_name_t target_name, gss_OID mech)
{
    gss_cred_id_t cred = GSS_C_NO_CREDENTIAL;
    gss_OID_set oidset;
    OM_uint32 junk, ret;

    if (target_name == GSS_C_NO_NAME)
	return GSS_S_COMPLETE;

    gss_create_empty_oid_set(&junk, &oidset);
    gss_add_oid_set_member(&junk, mech, &oidset);
    
    ret = gss_acquire_cred(&junk, target_name, GSS_C_INDEFINITE, oidset,
			   GSS_C_ACCEPT, &cred, NULL, NULL);
    gss_release_oid_set(&junk, &oidset);
    if (ret != GSS_S_COMPLETE)
	return ret;
    gss_release_cred(&junk, &cred);
    
    return GSS_S_COMPLETE;
}

static OM_uint32
send_supported_mechs (OM_uint32 *minor_status,
		      gss_buffer_t output_token)
{
    NegotiationTokenWin nt;
    char hostname[MAXHOSTNAMELEN + 1], *p;
    gss_buffer_desc name_buf;
    gss_OID name_type;
    gss_name_t target_princ;
    gss_name_t canon_princ;
    OM_uint32 minor;
    size_t buf_len;
    gss_buffer_desc data;
    OM_uint32 ret;

    memset(&nt, 0, sizeof(nt));

    nt.element = choice_NegotiationTokenWin_negTokenInit;
    nt.u.negTokenInit.reqFlags = NULL;
    nt.u.negTokenInit.mechToken = NULL;
    nt.u.negTokenInit.negHints = NULL;

    ret = _gss_spnego_indicate_mechtypelist(minor_status, GSS_C_NO_NAME,
					    acceptor_approved, 1, NULL,
					    &nt.u.negTokenInit.mechTypes, NULL);
    if (ret != GSS_S_COMPLETE) {
	return ret;
    }

    memset(&target_princ, 0, sizeof(target_princ));
    if (gethostname(hostname, sizeof(hostname) - 2) != 0) {
	*minor_status = errno;
	free_NegotiationTokenWin(&nt);
	return GSS_S_FAILURE;
    }
    hostname[sizeof(hostname) - 1] = '\0';

    /* Send the constructed SAM name for this host */
    for (p = hostname; *p != '\0' && *p != '.'; p++) {
	*p = toupper((unsigned char)*p);
    }
    *p++ = '$';
    *p = '\0';

    name_buf.length = strlen(hostname);
    name_buf.value = hostname;

    ret = gss_import_name(minor_status, &name_buf,
			  GSS_C_NO_OID,
			  &target_princ);
    if (ret != GSS_S_COMPLETE) {
	free_NegotiationTokenWin(&nt);
	return ret;
    }

    name_buf.length = 0;
    name_buf.value = NULL;

    /* Canonicalize the name using the preferred mechanism */
    ret = gss_canonicalize_name(minor_status,
				target_princ,
				GSS_C_NO_OID,
				&canon_princ);
    if (ret != GSS_S_COMPLETE) {
	free_NegotiationTokenWin(&nt);
	gss_release_name(&minor, &target_princ);
	return ret;
    }

    ret = gss_display_name(minor_status, canon_princ,
			   &name_buf, &name_type);
    if (ret != GSS_S_COMPLETE) {
	free_NegotiationTokenWin(&nt);
	gss_release_name(&minor, &canon_princ);
	gss_release_name(&minor, &target_princ);
	return ret;
    }

    gss_release_name(&minor, &canon_princ);
    gss_release_name(&minor, &target_princ);

    ALLOC(nt.u.negTokenInit.negHints, 1);
    if (nt.u.negTokenInit.negHints == NULL) {
	*minor_status = ENOMEM;
	gss_release_buffer(&minor, &name_buf);
	free_NegotiationTokenWin(&nt);
	return GSS_S_FAILURE;
    }

    ALLOC(nt.u.negTokenInit.negHints->hintName, 1);
    if (nt.u.negTokenInit.negHints->hintName == NULL) {
	*minor_status = ENOMEM;
	gss_release_buffer(&minor, &name_buf);
	free_NegotiationTokenWin(&nt);
	return GSS_S_FAILURE;
    }

    *(nt.u.negTokenInit.negHints->hintName) = name_buf.value;
    name_buf.value = NULL;
    nt.u.negTokenInit.negHints->hintAddress = NULL;

    ASN1_MALLOC_ENCODE(NegotiationTokenWin, 
		       data.value, data.length, &nt, &buf_len, ret);
    free_NegotiationTokenWin(&nt);
    if (ret) {
	return ret;
    }
    if (data.length != buf_len)
	abort();

    ret = gss_encapsulate_token(&data, GSS_SPNEGO_MECHANISM, output_token);

    free (data.value);

    if (ret != GSS_S_COMPLETE)
	return ret;

    *minor_status = 0;

    return GSS_S_CONTINUE_NEEDED;
}

static OM_uint32
send_accept (OM_uint32 *minor_status,
	     gssspnego_ctx context_handle,
	     gss_buffer_t mech_token,
	     int initial_response,
	     gss_buffer_t mech_buf,
	     gss_buffer_t output_token)
{
    NegotiationToken nt;
    OM_uint32 ret;
    gss_buffer_desc mech_mic_buf;
    size_t size;

    memset(&nt, 0, sizeof(nt));

    nt.element = choice_NegotiationToken_negTokenResp;

    ALLOC(nt.u.negTokenResp.negResult, 1);
    if (nt.u.negTokenResp.negResult == NULL) {
	*minor_status = ENOMEM;
	return GSS_S_FAILURE;
    }

    if (context_handle->open) {
	if (mech_token != GSS_C_NO_BUFFER
	    && mech_token->length != 0
	    && mech_buf != GSS_C_NO_BUFFER)
	    *(nt.u.negTokenResp.negResult)  = accept_incomplete;
	else
	    *(nt.u.negTokenResp.negResult)  = accept_completed;
    } else {
	if (initial_response && context_handle->require_mic)
	    *(nt.u.negTokenResp.negResult)  = request_mic;
	else
	    *(nt.u.negTokenResp.negResult)  = accept_incomplete;
    }

    if (initial_response) {
	ALLOC(nt.u.negTokenResp.supportedMech, 1);
	if (nt.u.negTokenResp.supportedMech == NULL) {
	    free_NegotiationToken(&nt);
	    *minor_status = ENOMEM;
	    return GSS_S_FAILURE;
	}

	ret = der_get_oid(context_handle->preferred_mech_type->elements,
			  context_handle->preferred_mech_type->length,
			  nt.u.negTokenResp.supportedMech,
			  NULL);
	if (ret) {
	    free_NegotiationToken(&nt);
	    *minor_status = ENOMEM;
	    return GSS_S_FAILURE;
	}
    } else {
	nt.u.negTokenResp.supportedMech = NULL;
    }

    if (mech_token != GSS_C_NO_BUFFER && mech_token->length != 0) {
	ALLOC(nt.u.negTokenResp.responseToken, 1);
	if (nt.u.negTokenResp.responseToken == NULL) {
	    free_NegotiationToken(&nt);
	    *minor_status = ENOMEM;
	    return GSS_S_FAILURE;
	}
	nt.u.negTokenResp.responseToken->length = mech_token->length;
	nt.u.negTokenResp.responseToken->data   = mech_token->value;
	mech_token->length = 0;
	mech_token->value  = NULL;
    } else {
	nt.u.negTokenResp.responseToken = NULL;
    }

    if (mech_buf != GSS_C_NO_BUFFER) {
	ret = gss_get_mic(minor_status,
			  context_handle->negotiated_ctx_id,
			  0,
			  mech_buf,
			  &mech_mic_buf);
	if (ret == GSS_S_COMPLETE) {
	    ALLOC(nt.u.negTokenResp.mechListMIC, 1);
	    if (nt.u.negTokenResp.mechListMIC == NULL) {
		gss_release_buffer(minor_status, &mech_mic_buf);
		free_NegotiationToken(&nt);
		*minor_status = ENOMEM;
		return GSS_S_FAILURE;
	    }
	    nt.u.negTokenResp.mechListMIC->length = mech_mic_buf.length;
	    nt.u.negTokenResp.mechListMIC->data   = mech_mic_buf.value;
	} else if (ret == GSS_S_UNAVAILABLE) {
	    nt.u.negTokenResp.mechListMIC = NULL;
	} else {
	    free_NegotiationToken(&nt);
	    return ret;
	}

    } else
	nt.u.negTokenResp.mechListMIC = NULL;
 
    ASN1_MALLOC_ENCODE(NegotiationToken,
		       output_token->value, output_token->length,
		       &nt, &size, ret);
    if (ret) {
	free_NegotiationToken(&nt);
	*minor_status = ret;
	return GSS_S_FAILURE;
    }

    /*
     * The response should not be encapsulated, because
     * it is a SubsequentContextToken (note though RFC 1964
     * specifies encapsulation for all _Kerberos_ tokens).
     */

    if (*(nt.u.negTokenResp.negResult) == accept_completed)
	ret = GSS_S_COMPLETE;
    else
	ret = GSS_S_CONTINUE_NEEDED;
    free_NegotiationToken(&nt);
    return ret;
}


static OM_uint32
verify_mechlist_mic
	   (OM_uint32 *minor_status,
	    gssspnego_ctx context_handle,
	    gss_buffer_t mech_buf,
	    heim_octet_string *mechListMIC
	   )
{
    OM_uint32 ret;
    gss_buffer_desc mic_buf;

    if (context_handle->verified_mic) {
	/* This doesn't make sense, we've already verified it? */
	*minor_status = 0;
	return GSS_S_DUPLICATE_TOKEN;
    }

    if (mechListMIC == NULL) {
	*minor_status = 0;
	return GSS_S_DEFECTIVE_TOKEN;
    }

    mic_buf.length = mechListMIC->length;
    mic_buf.value  = mechListMIC->data;

    ret = gss_verify_mic(minor_status,
			 context_handle->negotiated_ctx_id,
			 mech_buf,
			 &mic_buf,
			 NULL);

    if (ret != GSS_S_COMPLETE)
	ret = GSS_S_DEFECTIVE_TOKEN;

    return ret;
}

static OM_uint32
select_mech(OM_uint32 *minor_status, MechType *mechType, int verify_p,
	    gss_OID *mech_p)
{
    char mechbuf[64];
    size_t mech_len;
    gss_OID_desc oid;
    OM_uint32 ret, junk;

    ret = der_put_oid ((unsigned char *)mechbuf + sizeof(mechbuf) - 1,
		       sizeof(mechbuf),
		       mechType,
		       &mech_len);
    if (ret) {
	return GSS_S_DEFECTIVE_TOKEN;
    }

    oid.length   = mech_len;
    oid.elements = mechbuf + sizeof(mechbuf) - mech_len;

    if (gss_oid_equal(&oid, GSS_SPNEGO_MECHANISM)) {
	return GSS_S_BAD_MECH;
    }

    *minor_status = 0;

    /* Translate broken MS Kebreros OID */
    if (gss_oid_equal(&oid, &_gss_spnego_mskrb_mechanism_oid_desc)) {
	gssapi_mech_interface mech;

	mech = __gss_get_mechanism(&_gss_spnego_krb5_mechanism_oid_desc);
	if (mech == NULL)
	    return GSS_S_BAD_MECH;

	ret = gss_duplicate_oid(minor_status,
				&_gss_spnego_mskrb_mechanism_oid_desc,
				mech_p);
    } else {
	gssapi_mech_interface mech;

	mech = __gss_get_mechanism(&oid);
	if (mech == NULL)
	    return GSS_S_BAD_MECH;

	ret = gss_duplicate_oid(minor_status,
				&mech->gm_mech_oid,
				mech_p);
    }

    if (verify_p) {
	gss_name_t name = GSS_C_NO_NAME;
	gss_buffer_desc namebuf;
	char *str = NULL, *host, hostname[MAXHOSTNAMELEN];

	host = getenv("GSSAPI_SPNEGO_NAME");
	if (host == NULL || issuid()) {
	    if (gethostname(hostname, sizeof(hostname)) != 0) {
		*minor_status = errno;
		return GSS_S_FAILURE;
	    }
	    asprintf(&str, "host@%s", hostname);
	    host = str;
	}

	namebuf.length = strlen(host);
	namebuf.value = host;

	ret = gss_import_name(minor_status, &namebuf,
			      GSS_C_NT_HOSTBASED_SERVICE, &name);
	if (str)
	    free(str);
	if (ret != GSS_S_COMPLETE)
	    return ret;

	ret = acceptor_approved(name, *mech_p);
	gss_release_name(&junk, &name);
    }

    return ret;
}


static OM_uint32
acceptor_complete(OM_uint32 * minor_status,
		  gssspnego_ctx ctx,
		  int *get_mic,
		  gss_buffer_t mech_buf,
		  gss_buffer_t mech_input_token,
		  gss_buffer_t mech_output_token,
		  heim_octet_string *mic,
		  gss_buffer_t output_token)
{
    OM_uint32 ret;
    int require_mic, verify_mic;
    gss_buffer_desc buf;

    buf.length = 0;
    buf.value = NULL;

    ret = _gss_spnego_require_mechlist_mic(minor_status, ctx, &require_mic);
    if (ret)
	return ret;
    
    ctx->require_mic = require_mic;

    if (mic != NULL)
	require_mic = 1;
    
    if (ctx->open && require_mic) {
	if (mech_input_token == GSS_C_NO_BUFFER) { /* Even/One */
	    verify_mic = 1;
	    *get_mic = 0;
	} else if (mech_output_token != GSS_C_NO_BUFFER &&
		   mech_output_token->length == 0) { /* Odd */
	    *get_mic = verify_mic = 1;
	} else { /* Even/One */
	    verify_mic = 0;
	    *get_mic = 1;
	}
	
	if (verify_mic || get_mic) {
	    int eret;
	    size_t buf_len;
	    
	    ASN1_MALLOC_ENCODE(MechTypeList, 
			       mech_buf->value, mech_buf->length,
			       &ctx->initiator_mech_types, &buf_len, eret);
	    if (eret) {
		*minor_status = eret;
		return GSS_S_FAILURE;
	    }
	    if (buf.length != buf_len)
		abort();
	}
	
	if (verify_mic) {
	    ret = verify_mechlist_mic(minor_status, ctx, mech_buf, mic);
	    if (ret) {
		if (get_mic)
		    send_reject (minor_status, output_token);
		if (buf.value)
		    free(buf.value);
		return ret;
	    }