lib/libgss/g_glue.c

	g_glue.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

#include <mechglueP.h>
#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <errno.h>

#define MSO_BIT (8*(sizeof (int) - 1))  /* Most significant octet bit */

/*
 * This file contains the support routines for the glue layer.
 */

/*
 * get_der_length: Givin a pointer to a buffer that contains a DER encoded
 * length, decode the length updating the buffer to point to the character
 * after the DER encoding. The parameter bytes will point to the number of
 * bytes that made up the DER encoding of the length originally pointed to
 * by the buffer. Note we return -1 on error.
 */
int
get_der_length(unsigned char **buf, unsigned int buf_len, unsigned int *bytes)
{
    /* p points to the beginning of the buffer */
    unsigned char *p = *buf;
    int length, new_length;
    int octets;

    if (buf_len < 1)
        return (-1);

    /* We should have at least one byte */
    *bytes = 1;

    /*
     * If the High order bit is not set then the length is just the value
     * of *p.
     */
    if (*p < 128) {
        *buf = p+1; /* Advance the buffer */
    return (*p);        /* return the length */
    }

    /*
     * if the High order bit is set, then the low order bits represent
     * the number of bytes that contain the DER encoding of the length.
     */

    octets = *p++ & 0x7f;
    *bytes += octets;

    /* See if the supplied buffer contains enough bytes for the length. */
    if (octets > buf_len - 1)
        return (-1);

    /*
     * Calculate a multibyte length. The length is encoded as an
     * unsigned integer base 256.
     */
    for (length = 0; octets; octets--) {
        new_length = (length << 8) + *p++;
        if (new_length < length)  /* overflow */
            return (-1);
        length = new_length;
    }

    *buf = p; /* Advance the buffer */

    return (length);
}

/*
 * der_length_size: Return the number of bytes to encode a given length.
 */
unsigned int
der_length_size(unsigned int len)
{
    int i;

    if (len < 128)
        return (1);

    for (i = 0; len; i++) {
        len >>= 8;
    }

    return (i+1);
}

/*
 * put_der_length: Encode the supplied length into the buffer pointed to
 * by buf. max_length represents the maximum length of the buffer pointed
 * to by buff. We will advance buf to point to the character after the newly
 * DER encoded length. We return 0 on success or -l it the length cannot
 * be encoded in max_len characters.
 */
int
put_der_length(unsigned length, unsigned char **buf, unsigned int max_len)
{
    unsigned char *s = *buf, *p;
    unsigned int buf_len = 0;
    int i, first;

    /* Oops */
    if (buf == 0 || max_len < 1)
        return (-1);

    /* Single byte is the length */
    if (length < 128) {
        *s++ = length;
        *buf = s;
        return (0);
    }

    /* First byte contains the number of octets */
    p = s + 1;

    /* Running total of the DER encoding length */
    buf_len = 0;

    /*
     * Encode MSB first. We do the encoding by setting a shift
     * factor to MSO_BIT (24 for 32 bit words) and then shifting the length
     * by the factor. We then encode the resulting low order byte.
     * We subtract 8 from the shift factor and repeat to ecnode the next
     * byte. We stop when the shift factor is zero or we've run out of
     * buffer to encode into.
     */
    first = 0;
    for (i = MSO_BIT; i >= 0 && buf_len <= max_len; i -= 8) {
        unsigned int v;
        v = (length >> i) & 0xff;
        if ((v) || first) {
            buf_len += 1;
            *p++ = v;
            first = 1;
        }
    }
    if (i >= 0)         /* buffer overflow */
        return (-1);

    /*
     * We go back now and set the first byte to be the length with
     * the high order bit set.
     */
    *s = buf_len | 0x80;
    *buf = p;

    return (0);
}


/*
 *  glue routine for get_mech_type
 *
 */
OM_uint32
__gss_get_mech_type(OID, token)
    gss_OID         OID;
    const gss_buffer_t  token;
{
    unsigned char *buffer_ptr;
    int length;

    /*
     * This routine reads the prefix of "token" in order to determine
     * its mechanism type. It assumes the encoding suggested in
     * Appendix B of RFC 1508. This format starts out as follows :
     *
     * tag for APPLICATION 0, Sequence[constructed, definite length]
     * length of remainder of token
     * tag of OBJECT IDENTIFIER
     * length of mechanism OID
     * encoding of mechanism OID
     * <the rest of the token>
     *
     * Numerically, this looks like :
     *
     * 0x60
     * <length> - could be multiple bytes
     * 0x06
     * <length> - assume only one byte, hence OID length < 127
     * <mech OID bytes>
     *
     * The routine fills in the OID value and returns an error as necessary.
     */

    if (OID == NULL)
        return (GSS_S_CALL_INACCESSIBLE_WRITE);

    if ((token == NULL) || (token->value == NULL))
        return (GSS_S_DEFECTIVE_TOKEN);

    /* Skip past the APP/Sequnce byte and the token length */

    buffer_ptr = (unsigned char *) token->value;

    if (*(buffer_ptr++) != 0x60)
        return (GSS_S_DEFECTIVE_TOKEN);
    length = *buffer_ptr++;

    /* check if token length is null */
    if (length == 0)
        return (GSS_S_DEFECTIVE_TOKEN);

    if (length & 0x80) {
        if ((length & 0x7f) > 4)
            return (GSS_S_DEFECTIVE_TOKEN);
        buffer_ptr += length & 0x7f;
    }

    if (*(buffer_ptr++) != 0x06)
        return (GSS_S_DEFECTIVE_TOKEN);

    OID->length = (OM_uint32) *(buffer_ptr++);
    OID->elements = (void *) buffer_ptr;
    return (GSS_S_COMPLETE);
}


/*
 *  Internal routines to get and release an internal mechanism name
 */
OM_uint32 __gss_import_internal_name(minor_status, mech_type, union_name,
                    internal_name)
OM_uint32       *minor_status;
const gss_OID       mech_type;
gss_union_name_t    union_name;
gss_name_t      *internal_name;
{
    OM_uint32           status;
    gss_mechanism       mech;

    mech = __gss_get_mechanism(mech_type);
    if (mech) {
        if (mech->gss_import_name)
            status = mech->gss_import_name(
                        mech->context,
                        minor_status,
                        union_name->external_name,
                        union_name->name_type,
                        internal_name);
        else
            status = GSS_S_UNAVAILABLE;

        return (status);
    }

    return (GSS_S_BAD_MECH);
}


OM_uint32 __gss_export_internal_name(minor_status, mech_type,
        internal_name, name_buf)
OM_uint32       *minor_status;
const gss_OID       mech_type;
const gss_name_t    internal_name;
gss_buffer_t        name_buf;
{
    OM_uint32 status;
    gss_mechanism mech;
    gss_buffer_desc dispName;
    gss_OID nameOid;
    unsigned char *buf = NULL;
    const unsigned char tokId[] = "\x04\x01";
    const int tokIdLen = 2;
    const int mechOidLenLen = 2, mechOidTagLen = 1, nameLenLen = 4;
    int mechOidDERLen = 0;
    int mechOidLen = 0;

    mech = __gss_get_mechanism(mech_type);
    if (!mech)
        return (GSS_S_BAD_MECH);

    if (mech->gss_export_name)
        return (mech->gss_export_name(mech->context,
                        minor_status,
                        internal_name,
                        name_buf));

    /*
     * if we are here it is because the mechanism does not provide
     * a gss_export_name so we will use our implementation.  We
     * do required that the mechanism define a gss_display_name.
     */
    if (!mech->gss_display_name)
        return (GSS_S_UNAVAILABLE);

    /*
     * NOTE: RFC2743 (section 3.2) governs the format of the outer
     *   wrapper of exported names; the mechanisms' specs govern
     *   the format of the inner portion of the exported name
     *   and, for some (e.g., RFC1964, the Kerberos V mech), a
     *   generic default as implemented here will do.
     *
     * The outer wrapper of an exported MN is: 2-octet tok Id
     * (0x0401) + 2-octet network-byte order mech OID length + mech
     * oid (in DER format, including DER tag and DER length) +
     * 4-octet network-byte order length of inner portion + inner
     * portion.
     *
     * For the Kerberos V mechanism the inner portion of an exported
     * MN is the display name string and ignores the name type OID
     * altogether.  And we hope this will be so for any future
     * mechanisms also, so that factoring name export/import out of
     * the mech and into libgss pays off.
     */
    if ((status = mech->gss_display_name(mech->context,
                        minor_status,
                        internal_name,
                        &dispName,
                        &nameOid))
                        != GSS_S_COMPLETE)
        return (status);

    /* determine the size of the buffer needed */
    mechOidDERLen = der_length_size(mech_type->length);
    name_buf->length = tokIdLen + mechOidLenLen +
                mechOidTagLen + mechOidDERLen +
                mech_type->length +
                nameLenLen + dispName.length;
    if ((name_buf->value = (void*)malloc(name_buf->length)) ==
        (void*)NULL) {
            name_buf->length = 0;
            (void) gss_release_buffer(&status, &dispName);
            return (GSS_S_FAILURE);
    }

    /* now create the name ..... */
    buf = (unsigned char *)name_buf->value;
    (void) memset(name_buf->value, 0, name_buf->length);
    (void) memcpy(buf, tokId, tokIdLen);
    buf += tokIdLen;

    /* spec allows only 2 bytes for the mech oid length */
    mechOidLen = mechOidDERLen + mechOidTagLen + mech_type->length;
    *buf++ = (mechOidLen & 0xFF00) >> 8;
    *buf++ = (mechOidLen & 0x00FF);

    /*
     * DER Encoding of mech OID contains OID Tag (0x06), length and
     * mech OID value
     */
    *buf++ = 0x06;
    if (put_der_length(mech_type->length, &buf,
        (name_buf->length - tokIdLen -2)) != 0) {
        name_buf->length = 0;
        free(name_buf->value);
        (void) gss_release_buffer(&status, &dispName);
        return (GSS_S_FAILURE);
    }

    (void) memcpy(buf, mech_type->elements, mech_type->length);
    buf += mech_type->length;

    /* spec designates the next 4 bytes for the name length */
    *buf++ = (dispName.length & 0xFF000000) >> 24;
    *buf++ = (dispName.length & 0x00FF0000) >> 16;
    *buf++ = (dispName.length & 0x0000FF00) >> 8;
    *buf++ = (dispName.length & 0X000000FF);

    /* for the final ingredient - add the name from gss_display_name */
    (void) memcpy(buf, dispName.value, dispName.length);

    /* release the buffer obtained from gss_display_name */
    (void) gss_release_buffer(minor_status, &dispName);
    return (GSS_S_COMPLETE);
} /*  __gss_export_internal_name */


OM_uint32 __gss_display_internal_name(minor_status, mech_type, internal_name,
                        external_name, name_type)
OM_uint32       *minor_status;
const gss_OID       mech_type;
const gss_name_t    internal_name;
gss_buffer_t        external_name;
gss_OID         *name_type;
{
    OM_uint32           status;
    gss_mechanism       mech;

    mech = __gss_get_mechanism(mech_type);
    if (mech) {
        if (mech->gss_display_name)
            status = mech->gss_display_name(
                            mech->context,
                            minor_status,
                            internal_name,
                            external_name,
                            name_type);
        else
            status = GSS_S_UNAVAILABLE;

        return (status);
    }

    return (GSS_S_BAD_MECH);
}

OM_uint32
__gss_release_internal_name(minor_status, mech_type, internal_name)
OM_uint32       *minor_status;
const gss_OID       mech_type;
gss_name_t      *internal_name;
{
    OM_uint32           status;
    gss_mechanism       mech;

    mech = __gss_get_mechanism(mech_type);
    if (mech) {
        if (mech->gss_release_name)
            status = mech->gss_release_name(
                            mech->context,
                            minor_status,
                            internal_name);
        else
            status = GSS_S_UNAVAILABLE;

        return (status);
    }

    return (GSS_S_BAD_MECH);
}


/*
 * This function converts an internal gssapi name to a union gssapi
 * name.  Note that internal_name should be considered "consumed" by
 * this call, whether or not we return an error.
 */
OM_uint32 __gss_convert_name_to_union_name(minor_status, mech,
                        internal_name, external_name)
    OM_uint32 *minor_status;
    gss_mechanism       mech;
    gss_name_t      internal_name;
    gss_name_t      *external_name;
{
    OM_uint32 major_status, tmp;
    gss_union_name_t union_name;

    union_name = (gss_union_name_t)malloc(sizeof (gss_union_name_desc));
    if (!union_name) {
            goto allocation_failure;
    }
    union_name->mech_type = 0;
    union_name->mech_name = internal_name;
    union_name->name_type = 0;
    union_name->external_name = 0;

    major_status = generic_gss_copy_oid(minor_status, &mech->mech_type,
                        &union_name->mech_type);
    if (major_status != GSS_S_COMPLETE)
        goto allocation_failure;

    union_name->external_name =
        (gss_buffer_t)malloc(sizeof (gss_buffer_desc));
    if (!union_name->external_name) {
            goto allocation_failure;
    }

    major_status = mech->gss_display_name(mech->context, minor_status,
                        internal_name,
                        union_name->external_name,
                        &union_name->name_type);
    if (major_status != GSS_S_COMPLETE)
        goto allocation_failure;

    *external_name =  (gss_name_t)union_name;
    return (GSS_S_COMPLETE);

allocation_failure:
    if (union_name) {
        if (union_name->external_name) {
            if (union_name->external_name->value)
                free(union_name->external_name->value);
            free(union_name->external_name);
        }
        if (union_name->name_type)
            (void) gss_release_oid(&tmp, &union_name->name_type);
        if (union_name->mech_type)
            (void) gss_release_oid(&tmp, &union_name->mech_type);
        free(union_name);
    }
    /*
     * do as the top comment says - since we are now owners of
     * internal_name, we must clean it up
     */
    if (internal_name)
        (void) __gss_release_internal_name(&tmp, &mech->mech_type,
                        &internal_name);

    return (major_status);
}

/*
 * Glue routine for returning the mechanism-specific credential from a
 * external union credential.
 */
gss_cred_id_t
__gss_get_mechanism_cred(union_cred, mech_type)
    const gss_union_cred_t  union_cred;
    const gss_OID       mech_type;
{
    int         i;

    if (union_cred == (gss_union_cred_t)GSS_C_NO_CREDENTIAL)
        return (GSS_C_NO_CREDENTIAL);

    for (i = 0; i < union_cred->count; i++) {
        if (g_OID_equal(mech_type, &union_cred->mechs_array[i]))
            return (union_cred->cred_array[i]);
    }
    return (GSS_C_NO_CREDENTIAL);
}


/*
 * Routine to create and copy the gss_buffer_desc structure.
 * Both space for the structure and the data is allocated.
 */
OM_uint32
__gss_create_copy_buffer(srcBuf, destBuf, addNullChar)
    const gss_buffer_t  srcBuf;
    gss_buffer_t        *destBuf;
    int         addNullChar;
{
    gss_buffer_t aBuf;
    int len;

    if (destBuf == NULL)
        return (GSS_S_CALL_INACCESSIBLE_WRITE);

    *destBuf = 0;

    aBuf = (gss_buffer_t)malloc(sizeof (gss_buffer_desc));
    if (!aBuf)
        return (GSS_S_FAILURE);

    if (addNullChar)
        len = srcBuf->length + 1;
    else
        len = srcBuf->length;

    if (!(aBuf->value = (void*)malloc(len))) {
        free(aBuf);
        return (GSS_S_FAILURE);
    }


    (void) memcpy(aBuf->value, srcBuf->value, srcBuf->length);
    aBuf->length = srcBuf->length;
    *destBuf = aBuf;

    /* optionally add a NULL character */
    if (addNullChar)
        ((char *)aBuf->value)[aBuf->length] = '\0';

    return (GSS_S_COMPLETE);
} /* ****** __gss_create_copy_buffer  ****** */