net/sunrpc/auth_gss/gss_spkm3_token.c

   1 /*
   2  *  linux/net/sunrpc/gss_spkm3_token.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/random.h>
  41 #include <linux/crypto.h>
  42
  43 #ifdef RPC_DEBUG
  44 # define RPCDBG_FACILITY        RPCDBG_AUTH
  45 #endif
  46
  47 /*
  48  * asn1_bitstring_len()
  49  *
  50  * calculate the asn1 bitstring length of the xdr_netobject
  51  */
  52 void
  53 asn1_bitstring_len(struct xdr_netobj *in, int *enclen, int *zerobits)
  54 {
  55         int i, zbit = 0,elen = in->len;
  56         char *ptr;
  57
  58         ptr = &in->data[in->len -1];
  59
  60         /* count trailing 0's */
  61         for(i = in->len; i > 0; i--) {
  62                 if (*ptr == 0) {
  63                         ptr--;
  64                         elen--;
  65                 } else
  66                         break;
  67         }
  68
  69         /* count number of 0 bits in final octet */
  70         ptr = &in->data[elen - 1];
  71         for(i = 0; i < 8; i++) {
  72                 short mask = 0x01;
  73
  74                 if (!((mask << i) & *ptr))
  75                         zbit++;
  76                 else
  77                         break;
  78         }
  79         *enclen = elen;
  80         *zerobits = zbit;
  81 }
  82
  83 /*
  84  * decode_asn1_bitstring()
  85  *
  86  * decode a bitstring into a buffer of the expected length.
  87  * enclen = bit string length
  88  * explen = expected length (define in rfc)
  89  */
  90 int
  91 decode_asn1_bitstring(struct xdr_netobj *out, char *in, int enclen, int explen)
  92 {
  93         if (!(out->data = kzalloc(explen,GFP_KERNEL)))
  94                 return 0;
  95         out->len = explen;
  96         memcpy(out->data, in, enclen);
  97         return 1;
  98 }
  99
 100 /*
 101  * SPKMInnerContextToken choice SPKM_MIC asn1 token layout
 102  *
 103  * contextid is always 16 bytes plain data. max asn1 bitstring len = 17.
 104  *
 105  * tokenlen = pos[0] to end of token (max pos[45] with MD5 cksum)
 106  *
 107  * pos  value
 108  * ----------
 109  * [0]  a4  SPKM-MIC tag
 110  * [1]  ??  innertoken length  (max 44)
 111  *
 112  *
 113  * tok_hdr piece of checksum data starts here
 114  *
 115  * the maximum mic-header len = 9 + 17 = 26
 116  *      mic-header
 117  *      ----------
 118  * [2]  30      SEQUENCE tag
 119  * [3]  ??      mic-header length: (max 23) = TokenID + ContextID
 120  *
 121  *              TokenID  - all fields constant and can be hardcoded
 122  *              -------
 123  * [4]    02    Type 2
 124  * [5]    02    Length 2
 125  * [6][7] 01 01 TokenID (SPKM_MIC_TOK)
 126  *
 127  *              ContextID  - encoded length not constant, calculated
 128  *              ---------
 129  * [8]  03      Type 3
 130  * [9]  ??      encoded length
 131  * [10] ??      ctxzbit
 132  * [11]         contextid
 133  *
 134  * mic_header piece of checksum data ends here.
 135  *
 136  *      int-cksum - encoded length not constant, calculated
 137  *      ---------
 138  * [??] 03      Type 3
 139  * [??] ??      encoded length
 140  * [??] ??      md5zbit
 141  * [??]         int-cksum (NID_md5 = 16)
 142  *
 143  * maximum SPKM-MIC innercontext token length =
 144  *       10 + encoded contextid_size(17 max) + 2 + encoded
 145  *       cksum_size (17 maxfor NID_md5) = 46
 146  */
 147
 148 /*
 149  * spkm3_mic_header()
 150  *
 151  * Prepare the SPKM_MIC_TOK mic-header for check-sum calculation
 152  * elen: 16 byte context id asn1 bitstring encoded length
 153  */
 154 void
 155 spkm3_mic_header(unsigned char **hdrbuf, unsigned int *hdrlen, unsigned char *ctxdata, int elen, int zbit)
 156 {
 157         char *hptr = *hdrbuf;
 158         char *top = *hdrbuf;
 159
 160         *(u8 *)hptr++ = 0x30;
 161         *(u8 *)hptr++ = elen + 7;  /* on the wire header length */
 162
 163         /* tokenid */
 164         *(u8 *)hptr++ = 0x02;
 165         *(u8 *)hptr++ = 0x02;
 166         *(u8 *)hptr++ = 0x01;
 167         *(u8 *)hptr++ = 0x01;
 168
 169         /* coniextid */
 170         *(u8 *)hptr++ = 0x03;
 171         *(u8 *)hptr++ = elen + 1; /* add 1 to include zbit */
 172         *(u8 *)hptr++ = zbit;
 173         memcpy(hptr, ctxdata, elen);
 174         hptr += elen;
 175         *hdrlen = hptr - top;
 176 }
 177
 178 /*
 179  * spkm3_mic_innercontext_token()
 180  *
 181  * *tokp points to the beginning of the SPKM_MIC token  described
 182  * in rfc 2025, section 3.2.1:
 183  *
 184  * toklen is the inner token length
 185  */
 186 void
 187 spkm3_make_mic_token(unsigned char **tokp, int toklen, struct xdr_netobj *mic_hdr, struct xdr_netobj *md5cksum, int md5elen, int md5zbit)
 188 {
 189         unsigned char *ict = *tokp;
 190
 191         *(u8 *)ict++ = 0xa4;
 192         *(u8 *)ict++ = toklen;
 193         memcpy(ict, mic_hdr->data, mic_hdr->len);
 194         ict += mic_hdr->len;
 195
 196         *(u8 *)ict++ = 0x03;
 197         *(u8 *)ict++ = md5elen + 1; /* add 1 to include zbit */
 198         *(u8 *)ict++ = md5zbit;
 199         memcpy(ict, md5cksum->data, md5elen);
 200 }
 201
 202 u32
 203 spkm3_verify_mic_token(unsigned char **tokp, int *mic_hdrlen, unsigned char **cksum)
 204 {
 205         struct xdr_netobj       spkm3_ctx_id = {.len =0, .data = NULL};
 206         unsigned char           *ptr = *tokp;
 207         int                     ctxelen;
 208         u32                     ret = GSS_S_DEFECTIVE_TOKEN;
 209
 210         /* spkm3 innercontext token preamble */
 211         if ((ptr[0] != 0xa4) || (ptr[2] != 0x30)) {
 212                 dprintk("RPC: BAD SPKM ictoken preamble\n");
 213                 goto out;
 214         }
 215
 216         *mic_hdrlen = ptr[3];
 217
 218         /* token type */
 219         if ((ptr[4] != 0x02) || (ptr[5] != 0x02)) {
 220                 dprintk("RPC: BAD asn1 SPKM3 token type\n");
 221                 goto out;
 222         }
 223
 224         /* only support SPKM_MIC_TOK */
 225         if((ptr[6] != 0x01) || (ptr[7] != 0x01)) {
 226                 dprintk("RPC: ERROR unsupported SPKM3 token \n");
 227                 goto out;
 228         }
 229
 230         /* contextid */
 231         if (ptr[8] != 0x03) {
 232                 dprintk("RPC: BAD SPKM3 asn1 context-id type\n");
 233                 goto out;
 234         }
 235
 236         ctxelen = ptr[9];
 237         if (ctxelen > 17) {  /* length includes asn1 zbit octet */
 238                 dprintk("RPC: BAD SPKM3 contextid len %d\n", ctxelen);
 239                 goto out;
 240         }
 241
 242         /* ignore ptr[10] */
 243
 244         if(!decode_asn1_bitstring(&spkm3_ctx_id, &ptr[11], ctxelen - 1, 16))
 245                 goto out;
 246
 247         /*
 248         * in the current implementation: the optional int-alg is not present
 249         * so the default int-alg (md5) is used the optional snd-seq field is
 250         * also not present
 251         */
 252
 253         if (*mic_hdrlen != 6 + ctxelen) {
 254                 dprintk("RPC: BAD SPKM_ MIC_TOK header len %d: we only support default int-alg (should be absent) and do not support snd-seq\n", *mic_hdrlen);
 255                 goto out;
 256         }
 257         /* checksum */
 258         *cksum = (&ptr[10] + ctxelen); /* ctxelen includes ptr[10] */
 259
 260         ret = GSS_S_COMPLETE;
 261 out:
 262         kfree(spkm3_ctx_id.data);
 263         return ret;
 264 }
 265