root/net/sunrpc/auth_gss/gss_spkm3_unseal.c

DEFINITIONS

1. spkm3_read_token

/*
 *  linux/net/sunrpc/gss_spkm3_unseal.c
 *
 *  Copyright (c) 2003 The Regents of the University of Michigan.
 *  All rights reserved.
 *
 *  Andy Adamson <andros@umich.edu>
 *
 *  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 University 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 ``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 REGENTS 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 <linux/types.h>
#include <linux/slab.h>
#include <linux/jiffies.h>
#include <linux/sunrpc/gss_spkm3.h>
#include <linux/crypto.h>

#ifdef RPC_DEBUG
# define RPCDBG_FACILITY        RPCDBG_AUTH
#endif

/*
 * spkm3_read_token()
 *
 * only SPKM_MIC_TOK with md5 intg-alg is supported
 */
u32
spkm3_read_token(struct spkm3_ctx *ctx,
                struct xdr_netobj *read_token,    /* checksum */
                struct xdr_buf *message_buffer, /* signbuf */
                int toktype)
{
        s32                     checksum_type;
        s32                     code;
        struct xdr_netobj       wire_cksum = {.len =0, .data = NULL};
        char                    cksumdata[16];
        struct xdr_netobj       md5cksum = {.len = 0, .data = cksumdata};
        unsigned char           *ptr = (unsigned char *)read_token->data;
        unsigned char           *cksum;
        int                     bodysize, md5elen;
        int                     mic_hdrlen;
        u32                     ret = GSS_S_DEFECTIVE_TOKEN;

        if (g_verify_token_header((struct xdr_netobj *) &ctx->mech_used,
                                        &bodysize, &ptr, read_token->len))
                goto out;

        /* decode the token */

        if (toktype != SPKM_MIC_TOK) {
                dprintk("RPC:       BAD SPKM3 token type: %d\n", toktype);
                goto out;
        }

        if ((ret = spkm3_verify_mic_token(&ptr, &mic_hdrlen, &cksum)))
                goto out;

        if (*cksum++ != 0x03) {
                dprintk("RPC:       spkm3_read_token BAD checksum type\n");
                goto out;
        }
        md5elen = *cksum++;
        cksum++;        /* move past the zbit */

        if (!decode_asn1_bitstring(&wire_cksum, cksum, md5elen - 1, 16))
                goto out;

        /* HARD CODED FOR MD5 */

        /* compute the checksum of the message.
         * ptr + 2 = start of header piece of checksum
         * mic_hdrlen + 2 = length of header piece of checksum
         */
        ret = GSS_S_DEFECTIVE_TOKEN;
        if (!g_OID_equal(&ctx->intg_alg, &hmac_md5_oid)) {
                dprintk("RPC:       gss_spkm3_seal: unsupported I-ALG "
                                "algorithm\n");
                goto out;
        }

        checksum_type = CKSUMTYPE_HMAC_MD5;

        code = make_spkm3_checksum(checksum_type,
                &ctx->derived_integ_key, ptr + 2, mic_hdrlen + 2,
                message_buffer, 0, &md5cksum);

        if (code)
                goto out;

        ret = GSS_S_BAD_SIG;
        code = memcmp(md5cksum.data, wire_cksum.data, wire_cksum.len);
        if (code) {
                dprintk("RPC:       bad MIC checksum\n");
                goto out;
        }


        /* XXX: need to add expiration and sequencing */
        ret = GSS_S_COMPLETE;
out:
        kfree(wire_cksum.data);
        return ret;
}