LXR linux/net/sunrpc/auth_gss/gss_spkm3

   1/*
   2 *  linux/net/sunrpc/gss_spkm3_unseal.c
   3 *
   4 *  Copyright (c) 2003 The Regents of the University of Michigan.
   5 *  All rights reserved.
   6 *
   7 *  Andy Adamson <andros@umich.edu>
   8 *
   9 *  Redistribution and use in source and binary forms, with or without
  10 *  modification, are permitted provided that the following conditions
  11 *  are met:
  12 *
  13 *  1. Redistributions of source code must retain the above copyright
  14 *     notice, this list of conditions and the following disclaimer.
  15 *  2. Redistributions in binary form must reproduce the above copyright
  16 *     notice, this list of conditions and the following disclaimer in the
  17 *     documentation and/or other materials provided with the distribution.
  18 *  3. Neither the name of the University nor the names of its
  19 *     contributors may be used to endorse or promote products derived
  20 *     from this software without specific prior written permission.
  21 *
  22 *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
  23 *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  24 *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  25 *  DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26 *  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  27 *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  28 *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
  29 *  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  30 *  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  31 *  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  32 *  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  33 *
  34 */
  35
  36#include <linux/types.h>
  37#include <linux/slab.h>
  38#include <linux/jiffies.h>
  39#include <linux/sunrpc/gss_spkm3.h>
  40#include <linux/crypto.h>
  41
  42#ifdef RPC_DEBUG
  43# define RPCDBG_FACILITY        RPCDBG_AUTH
  44#endif
  45
  46/*
  47 * spkm3_read_token()
  48 *
  49 * only SPKM_MIC_TOK with md5 intg-alg is supported
  50 */
  51u32
  52spkm3_read_token(struct spkm3_ctx *ctx,
  53                struct xdr_netobj *read_token,    /* checksum */
  54                struct xdr_buf *message_buffer, /* signbuf */
  55                int toktype)
  56{
  57        s32                     checksum_type;
  58        s32                     code;
  59        struct xdr_netobj       wire_cksum = {.len =0, .data = NULL};
  60        char                    cksumdata[16];
  61        struct xdr_netobj       md5cksum = {.len = 0, .data = cksumdata};
  62        unsigned char           *ptr = (unsigned char *)read_token->data;
  63        unsigned char           *cksum;
  64        int                     bodysize, md5elen;
  65        int                     mic_hdrlen;
  66        u32                     ret = GSS_S_DEFECTIVE_TOKEN;
  67
  68        if (g_verify_token_header((struct xdr_netobj *) &ctx->mech_used,
  69                                        &bodysize, &ptr, read_token->len))
  70                goto out;
  71
  72        /* decode the token */
  73
  74        if (toktype != SPKM_MIC_TOK) {
  75                dprintk("RPC:       BAD SPKM3 token type: %d\n", toktype);
  76                goto out;
  77        }
  78
  79        if ((ret = spkm3_verify_mic_token(&ptr, &mic_hdrlen, &cksum)))
  80                goto out;
  81
  82        if (*cksum++ != 0x03) {
  83                dprintk("RPC:       spkm3_read_token BAD checksum type\n");
  84                goto out;
  85        }
  86        md5elen = *cksum++;
  87        cksum++;        /* move past the zbit */
  88
  89        if (!decode_asn1_bitstring(&wire_cksum, cksum, md5elen - 1, 16))
  90                goto out;
  91
  92        /* HARD CODED FOR MD5 */
  93
  94        /* compute the checksum of the message.
  95         * ptr + 2 = start of header piece of checksum
  96         * mic_hdrlen + 2 = length of header piece of checksum
  97         */
  98        ret = GSS_S_DEFECTIVE_TOKEN;
  99        if (!g_OID_equal(&ctx->intg_alg, &hmac_md5_oid)) {
 100                dprintk("RPC:       gss_spkm3_seal: unsupported I-ALG "
 101                                "algorithm\n");
 102                goto out;
 103        }
 104
 105        checksum_type = CKSUMTYPE_HMAC_MD5;
 106
 107        code = make_spkm3_checksum(checksum_type,
 108                &ctx->derived_integ_key, ptr + 2, mic_hdrlen + 2,
 109                message_buffer, 0, &md5cksum);
 110
 111        if (code)
 112                goto out;
 113
 114        ret = GSS_S_BAD_SIG;
 115        code = memcmp(md5cksum.data, wire_cksum.data, wire_cksum.len);
 116        if (code) {
 117                dprintk("RPC:       bad MIC checksum\n");
 118                goto out;
 119        }
 120
 121
 122        /* XXX: need to add expiration and sequencing */
 123        ret = GSS_S_COMPLETE;
 124out:
 125        kfree(wire_cksum.data);
 126        return ret;
 127}
 128