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 = kmalloc(explen,GFP_KERNEL)))
  94                 return 0;
  95         out->len = explen;
  96         memset(out->data, 0, explen);
  97         memcpy(out->data, in, enclen);
  98         return 1;
  99 }
 100
 101 /*
 102  * SPKMInnerContextToken choice SPKM_MIC asn1 token layout
 103  *
 104  * contextid is always 16 bytes plain data. max asn1 bitstring len = 17.
 105  *
 106  * tokenlen = pos[0] to end of token (max pos[45] with MD5 cksum)
 107  *
 108  * pos  value
 109  * ----------
 110  * [0]  a4  SPKM-MIC tag
 111  * [1]  ??  innertoken length  (max 44)
 112  *
 113  *
 114  * tok_hdr piece of checksum data starts here
 115  *
 116  * the maximum mic-header len = 9 + 17 = 26
 117  *      mic-header
 118  *      ----------
 119  * [2]  30      SEQUENCE tag
 120  * [3]  ??      mic-header length: (max 23) = TokenID + ContextID
 121  *
 122  *              TokenID  - all fields constant and can be hardcoded
 123  *              -------
 124  * [4]    02    Type 2
 125  * [5]    02    Length 2
 126  * [6][7] 01 01 TokenID (SPKM_MIC_TOK)
 127  *
 128  *              ContextID  - encoded length not constant, calculated
 129  *              ---------
 130  * [8]  03      Type 3
 131  * [9]  ??      encoded length
 132  * [10] ??      ctxzbit
 133  * [11]         contextid
 134  *
 135  * mic_header piece of checksum data ends here.
 136  *
 137  *      int-cksum - encoded length not constant, calculated
 138  *      ---------
 139  * [??] 03      Type 3
 140  * [??] ??      encoded length
 141  * [??] ??      md5zbit
 142  * [??]         int-cksum (NID_md5 = 16)
 143  *
 144  * maximum SPKM-MIC innercontext token length =
 145  *       10 + encoded contextid_size(17 max) + 2 + encoded
 146  *       cksum_size (17 maxfor NID_md5) = 46
 147  */
 148
 149 /*
 150  * spkm3_mic_header()
 151  *
 152  * Prepare the SPKM_MIC_TOK mic-header for check-sum calculation
 153  * elen: 16 byte context id asn1 bitstring encoded length
 154  */
 155 void
 156 spkm3_mic_header(unsigned char **hdrbuf, unsigned int *hdrlen, unsigned char *ctxdata, int elen, int zbit)
 157 {
 158         char *hptr = *hdrbuf;
 159         char *top = *hdrbuf;
 160
 161         *(u8 *)hptr++ = 0x30;
 162         *(u8 *)hptr++ = elen + 7;  /* on the wire header length */
 163
 164         /* tokenid */
 165         *(u8 *)hptr++ = 0x02;
 166         *(u8 *)hptr++ = 0x02;
 167         *(u8 *)hptr++ = 0x01;
 168         *(u8 *)hptr++ = 0x01;
 169
 170         /* coniextid */
 171         *(u8 *)hptr++ = 0x03;
 172         *(u8 *)hptr++ = elen + 1; /* add 1 to include zbit */
 173         *(u8 *)hptr++ = zbit;
 174         memcpy(hptr, ctxdata, elen);
 175         hptr += elen;
 176         *hdrlen = hptr - top;
 177 }
 178
 179 /*
 180  * spkm3_mic_innercontext_token()
 181  *
 182  * *tokp points to the beginning of the SPKM_MIC token  described
 183  * in rfc 2025, section 3.2.1:
 184  *
 185  * toklen is the inner token length
 186  */
 187 void
 188 spkm3_make_mic_token(unsigned char **tokp, int toklen, struct xdr_netobj *mic_hdr, struct xdr_netobj *md5cksum, int md5elen, int md5zbit)
 189 {
 190         unsigned char *ict = *tokp;
 191
 192         *(u8 *)ict++ = 0xa4;
 193         *(u8 *)ict++ = toklen;
 194         memcpy(ict, mic_hdr->data, mic_hdr->len);
 195         ict += mic_hdr->len;
 196
 197         *(u8 *)ict++ = 0x03;
 198         *(u8 *)ict++ = md5elen + 1; /* add 1 to include zbit */
 199         *(u8 *)ict++ = md5zbit;
 200         memcpy(ict, md5cksum->data, md5elen);
 201 }
 202
 203 u32
 204 spkm3_verify_mic_token(unsigned char **tokp, int *mic_hdrlen, unsigned char **cksum)
 205 {
 206         struct xdr_netobj       spkm3_ctx_id = {.len =0, .data = NULL};
 207         unsigned char           *ptr = *tokp;
 208         int                     ctxelen;
 209         u32                     ret = GSS_S_DEFECTIVE_TOKEN;
 210
 211         /* spkm3 innercontext token preamble */
 212         if ((ptr[0] != 0xa4) || (ptr[2] != 0x30)) {
 213                 dprintk("RPC: BAD SPKM ictoken preamble\n");
 214                 goto out;
 215         }
 216
 217         *mic_hdrlen = ptr[3];
 218
 219         /* token type */
 220         if ((ptr[4] != 0x02) || (ptr[5] != 0x02)) {
 221                 dprintk("RPC: BAD asn1 SPKM3 token type\n");
 222                 goto out;
 223         }
 224
 225         /* only support SPKM_MIC_TOK */
 226         if((ptr[6] != 0x01) || (ptr[7] != 0x01)) {
 227                 dprintk("RPC: ERROR unsupported SPKM3 token \n");
 228                 goto out;
 229         }
 230
 231         /* contextid */
 232         if (ptr[8] != 0x03) {
 233                 dprintk("RPC: BAD SPKM3 asn1 context-id type\n");
 234                 goto out;
 235         }
 236
 237         ctxelen = ptr[9];
 238         if (ctxelen > 17) {  /* length includes asn1 zbit octet */
 239                 dprintk("RPC: BAD SPKM3 contextid len %d\n", ctxelen);
 240                 goto out;
 241         }
 242
 243         /* ignore ptr[10] */
 244
 245         if(!decode_asn1_bitstring(&spkm3_ctx_id, &ptr[11], ctxelen - 1, 16))
 246                 goto out;
 247
 248         /*
 249         * in the current implementation: the optional int-alg is not present
 250         * so the default int-alg (md5) is used the optional snd-seq field is
 251         * also not present
 252         */
 253
 254         if (*mic_hdrlen != 6 + ctxelen) {
 255                 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);
 256                 goto out;
 257         }
 258         /* checksum */
 259         *cksum = (&ptr[10] + ctxelen); /* ctxelen includes ptr[10] */
 260
 261         ret = GSS_S_COMPLETE;
 262 out:
 263         kfree(spkm3_ctx_id.data);
 264         return ret;
 265 }
 266