net/sunrpc/auth_gss/gss_spkm3_unseal.c

   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  */
  51 u32
  52 spkm3_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;
 124 out:
 125         kfree(wire_cksum.data);
 126         return ret;
 127 }