net/sunrpc/auth_gss/gss_generic_token.c

   1 /*
   2  *  linux/net/sunrpc/gss_generic_token.c
   3  *
   4  *  Adapted from MIT Kerberos 5-1.2.1 lib/gssapi/generic/util_token.c
   5  *
   6  *  Copyright (c) 2000 The Regents of the University of Michigan.
   7  *  All rights reserved.
   8  *
   9  *  Andy Adamson   <andros@umich.edu>
  10  */
  11
  12 /*
  13  * Copyright 1993 by OpenVision Technologies, Inc.
  14  *
  15  * Permission to use, copy, modify, distribute, and sell this software
  16  * and its documentation for any purpose is hereby granted without fee,
  17  * provided that the above copyright notice appears in all copies and
  18  * that both that copyright notice and this permission notice appear in
  19  * supporting documentation, and that the name of OpenVision not be used
  20  * in advertising or publicity pertaining to distribution of the software
  21  * without specific, written prior permission. OpenVision makes no
  22  * representations about the suitability of this software for any
  23  * purpose.  It is provided "as is" without express or implied warranty.
  24  *
  25  * OPENVISION DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
  26  * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
  27  * EVENT SHALL OPENVISION BE LIABLE FOR ANY SPECIAL, INDIRECT OR
  28  * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
  29  * USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
  30  * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  31  * PERFORMANCE OF THIS SOFTWARE.
  32  */
  33
  34 #include <linux/types.h>
  35 #include <linux/module.h>
  36 #include <linux/slab.h>
  37 #include <linux/string.h>
  38 #include <linux/sunrpc/sched.h>
  39 #include <linux/sunrpc/gss_asn1.h>
  40
  41
  42 #ifdef RPC_DEBUG
  43 # define RPCDBG_FACILITY        RPCDBG_AUTH
  44 #endif
  45
  46
  47 /* TWRITE_STR from gssapiP_generic.h */
  48 #define TWRITE_STR(ptr, str, len) \
  49         memcpy((ptr), (char *) (str), (len)); \
  50         (ptr) += (len);
  51
  52 /* XXXX this code currently makes the assumption that a mech oid will
  53    never be longer than 127 bytes.  This assumption is not inherent in
  54    the interfaces, so the code can be fixed if the OSI namespace
  55    balloons unexpectedly. */
  56
  57 /* Each token looks like this:
  58
  59 0x60                            tag for APPLICATION 0, SEQUENCE
  60                                         (constructed, definite-length)
  61         <length>                possible multiple bytes, need to parse/generate
  62         0x06                    tag for OBJECT IDENTIFIER
  63                 <moid_length>   compile-time constant string (assume 1 byte)
  64                 <moid_bytes>    compile-time constant string
  65         <inner_bytes>           the ANY containing the application token
  66                                         bytes 0,1 are the token type
  67                                         bytes 2,n are the token data
  68
  69 For the purposes of this abstraction, the token "header" consists of
  70 the sequence tag and length octets, the mech OID DER encoding, and the
  71 first two inner bytes, which indicate the token type.  The token
  72 "body" consists of everything else.
  73
  74 */
  75
  76 static int
  77 der_length_size( int length)
  78 {
  79         if (length < (1<<7))
  80                 return(1);
  81         else if (length < (1<<8))
  82                 return(2);
  83 #if (SIZEOF_INT == 2)
  84         else
  85                 return(3);
  86 #else
  87         else if (length < (1<<16))
  88                 return(3);
  89         else if (length < (1<<24))
  90                 return(4);
  91         else
  92                 return(5);
  93 #endif
  94 }
  95
  96 static void
  97 der_write_length(unsigned char **buf, int length)
  98 {
  99         if (length < (1<<7)) {
 100                 *(*buf)++ = (unsigned char) length;
 101         } else {
 102                 *(*buf)++ = (unsigned char) (der_length_size(length)+127);
 103 #if (SIZEOF_INT > 2)
 104                 if (length >= (1<<24))
 105                         *(*buf)++ = (unsigned char) (length>>24);
 106                 if (length >= (1<<16))
 107                         *(*buf)++ = (unsigned char) ((length>>16)&0xff);
 108 #endif
 109                 if (length >= (1<<8))
 110                         *(*buf)++ = (unsigned char) ((length>>8)&0xff);
 111                 *(*buf)++ = (unsigned char) (length&0xff);
 112         }
 113 }
 114
 115 /* returns decoded length, or < 0 on failure.  Advances buf and
 116    decrements bufsize */
 117
 118 static int
 119 der_read_length(unsigned char **buf, int *bufsize)
 120 {
 121         unsigned char sf;
 122         int ret;
 123
 124         if (*bufsize < 1)
 125                 return(-1);
 126         sf = *(*buf)++;
 127         (*bufsize)--;
 128         if (sf & 0x80) {
 129                 if ((sf &= 0x7f) > ((*bufsize)-1))
 130                         return(-1);
 131                 if (sf > SIZEOF_INT)
 132                         return (-1);
 133                 ret = 0;
 134                 for (; sf; sf--) {
 135                         ret = (ret<<8) + (*(*buf)++);
 136                         (*bufsize)--;
 137                 }
 138         } else {
 139                 ret = sf;
 140         }
 141
 142         return(ret);
 143 }
 144
 145 /* returns the length of a token, given the mech oid and the body size */
 146
 147 int
 148 g_token_size(struct xdr_netobj *mech, unsigned int body_size)
 149 {
 150         /* set body_size to sequence contents size */
 151         body_size += 4 + (int) mech->len;         /* NEED overflow check */
 152         return(1 + der_length_size(body_size) + body_size);
 153 }
 154
 155 EXPORT_SYMBOL(g_token_size);
 156
 157 /* fills in a buffer with the token header.  The buffer is assumed to
 158    be the right size.  buf is advanced past the token header */
 159
 160 void
 161 g_make_token_header(struct xdr_netobj *mech, int body_size, unsigned char **buf)
 162 {
 163         *(*buf)++ = 0x60;
 164         der_write_length(buf, 4 + mech->len + body_size);
 165         *(*buf)++ = 0x06;
 166         *(*buf)++ = (unsigned char) mech->len;
 167         TWRITE_STR(*buf, mech->data, ((int) mech->len));
 168 }
 169
 170 EXPORT_SYMBOL(g_make_token_header);
 171
 172 /*
 173  * Given a buffer containing a token, reads and verifies the token,
 174  * leaving buf advanced past the token header, and setting body_size
 175  * to the number of remaining bytes.  Returns 0 on success,
 176  * G_BAD_TOK_HEADER for a variety of errors, and G_WRONG_MECH if the
 177  * mechanism in the token does not match the mech argument.  buf and
 178  * *body_size are left unmodified on error.
 179  */
 180 u32
 181 g_verify_token_header(struct xdr_netobj *mech, int *body_size,
 182                       unsigned char **buf_in, int toksize)
 183 {
 184         unsigned char *buf = *buf_in;
 185         int seqsize;
 186         struct xdr_netobj toid;
 187         int ret = 0;
 188
 189         if ((toksize-=1) < 0)
 190                 return(G_BAD_TOK_HEADER);
 191         if (*buf++ != 0x60)
 192                 return(G_BAD_TOK_HEADER);
 193
 194         if ((seqsize = der_read_length(&buf, &toksize)) < 0)
 195                 return(G_BAD_TOK_HEADER);
 196
 197         if (seqsize != toksize)
 198                 return(G_BAD_TOK_HEADER);
 199
 200         if ((toksize-=1) < 0)
 201                 return(G_BAD_TOK_HEADER);
 202         if (*buf++ != 0x06)
 203                 return(G_BAD_TOK_HEADER);
 204
 205         if ((toksize-=1) < 0)
 206                 return(G_BAD_TOK_HEADER);
 207         toid.len = *buf++;
 208
 209         if ((toksize-=toid.len) < 0)
 210                 return(G_BAD_TOK_HEADER);
 211         toid.data = buf;
 212         buf+=toid.len;
 213
 214         if (! g_OID_equal(&toid, mech))
 215                 ret = G_WRONG_MECH;
 216
 217    /* G_WRONG_MECH is not returned immediately because it's more important
 218       to return G_BAD_TOK_HEADER if the token header is in fact bad */
 219
 220         if ((toksize-=2) < 0)
 221                 return(G_BAD_TOK_HEADER);
 222
 223         if (ret)
 224                 return(ret);
 225
 226         if (!ret) {
 227                 *buf_in = buf;
 228                 *body_size = toksize;
 229         }
 230
 231         return(ret);
 232 }
 233
 234 EXPORT_SYMBOL(g_verify_token_header);
 235