linux/net/sunrpc/auth_gss/gss_generic_token.c
<<
>>
Prefs
   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/string.h>
  37#include <linux/sunrpc/sched.h>
  38#include <linux/sunrpc/gss_asn1.h>
  39
  40
  41#ifdef RPC_DEBUG
  42# define RPCDBG_FACILITY        RPCDBG_AUTH
  43#endif
  44
  45
  46/* TWRITE_STR from gssapiP_generic.h */
  47#define TWRITE_STR(ptr, str, len) \
  48        memcpy((ptr), (char *) (str), (len)); \
  49        (ptr) += (len);
  50
  51/* XXXX this code currently makes the assumption that a mech oid will
  52   never be longer than 127 bytes.  This assumption is not inherent in
  53   the interfaces, so the code can be fixed if the OSI namespace
  54   balloons unexpectedly. */
  55
  56/* Each token looks like this:
  57
  580x60                            tag for APPLICATION 0, SEQUENCE
  59                                        (constructed, definite-length)
  60        <length>                possible multiple bytes, need to parse/generate
  61        0x06                    tag for OBJECT IDENTIFIER
  62                <moid_length>   compile-time constant string (assume 1 byte)
  63                <moid_bytes>    compile-time constant string
  64        <inner_bytes>           the ANY containing the application token
  65                                        bytes 0,1 are the token type
  66                                        bytes 2,n are the token data
  67
  68For the purposes of this abstraction, the token "header" consists of
  69the sequence tag and length octets, the mech OID DER encoding, and the
  70first two inner bytes, which indicate the token type.  The token
  71"body" consists of everything else.
  72
  73*/
  74
  75static int
  76der_length_size( int length)
  77{
  78        if (length < (1<<7))
  79                return(1);
  80        else if (length < (1<<8))
  81                return(2);
  82#if (SIZEOF_INT == 2)
  83        else
  84                return(3);
  85#else
  86        else if (length < (1<<16))
  87                return(3);
  88        else if (length < (1<<24))
  89                return(4);
  90        else
  91                return(5);
  92#endif
  93}
  94
  95static void
  96der_write_length(unsigned char **buf, int length)
  97{
  98        if (length < (1<<7)) {
  99                *(*buf)++ = (unsigned char) length;
 100        } else {
 101                *(*buf)++ = (unsigned char) (der_length_size(length)+127);
 102#if (SIZEOF_INT > 2)
 103                if (length >= (1<<24))
 104                        *(*buf)++ = (unsigned char) (length>>24);
 105                if (length >= (1<<16))
 106                        *(*buf)++ = (unsigned char) ((length>>16)&0xff);
 107#endif
 108                if (length >= (1<<8))
 109                        *(*buf)++ = (unsigned char) ((length>>8)&0xff);
 110                *(*buf)++ = (unsigned char) (length&0xff);
 111        }
 112}
 113
 114/* returns decoded length, or < 0 on failure.  Advances buf and
 115   decrements bufsize */
 116
 117static int
 118der_read_length(unsigned char **buf, int *bufsize)
 119{
 120        unsigned char sf;
 121        int ret;
 122
 123        if (*bufsize < 1)
 124                return(-1);
 125        sf = *(*buf)++;
 126        (*bufsize)--;
 127        if (sf & 0x80) {
 128                if ((sf &= 0x7f) > ((*bufsize)-1))
 129                        return(-1);
 130                if (sf > SIZEOF_INT)
 131                        return (-1);
 132                ret = 0;
 133                for (; sf; sf--) {
 134                        ret = (ret<<8) + (*(*buf)++);
 135                        (*bufsize)--;
 136                }
 137        } else {
 138                ret = sf;
 139        }
 140
 141        return(ret);
 142}
 143
 144/* returns the length of a token, given the mech oid and the body size */
 145
 146int
 147g_token_size(struct xdr_netobj *mech, unsigned int body_size)
 148{
 149        /* set body_size to sequence contents size */
 150        body_size += 2 + (int) mech->len;         /* NEED overflow check */
 151        return(1 + der_length_size(body_size) + body_size);
 152}
 153
 154EXPORT_SYMBOL_GPL(g_token_size);
 155
 156/* fills in a buffer with the token header.  The buffer is assumed to
 157   be the right size.  buf is advanced past the token header */
 158
 159void
 160g_make_token_header(struct xdr_netobj *mech, int body_size, unsigned char **buf)
 161{
 162        *(*buf)++ = 0x60;
 163        der_write_length(buf, 2 + mech->len + body_size);
 164        *(*buf)++ = 0x06;
 165        *(*buf)++ = (unsigned char) mech->len;
 166        TWRITE_STR(*buf, mech->data, ((int) mech->len));
 167}
 168
 169EXPORT_SYMBOL_GPL(g_make_token_header);
 170
 171/*
 172 * Given a buffer containing a token, reads and verifies the token,
 173 * leaving buf advanced past the token header, and setting body_size
 174 * to the number of remaining bytes.  Returns 0 on success,
 175 * G_BAD_TOK_HEADER for a variety of errors, and G_WRONG_MECH if the
 176 * mechanism in the token does not match the mech argument.  buf and
 177 * *body_size are left unmodified on error.
 178 */
 179u32
 180g_verify_token_header(struct xdr_netobj *mech, int *body_size,
 181                      unsigned char **buf_in, int toksize)
 182{
 183        unsigned char *buf = *buf_in;
 184        int seqsize;
 185        struct xdr_netobj toid;
 186        int ret = 0;
 187
 188        if ((toksize-=1) < 0)
 189                return(G_BAD_TOK_HEADER);
 190        if (*buf++ != 0x60)
 191                return(G_BAD_TOK_HEADER);
 192
 193        if ((seqsize = der_read_length(&buf, &toksize)) < 0)
 194                return(G_BAD_TOK_HEADER);
 195
 196        if (seqsize != toksize)
 197                return(G_BAD_TOK_HEADER);
 198
 199        if ((toksize-=1) < 0)
 200                return(G_BAD_TOK_HEADER);
 201        if (*buf++ != 0x06)
 202                return(G_BAD_TOK_HEADER);
 203
 204        if ((toksize-=1) < 0)
 205                return(G_BAD_TOK_HEADER);
 206        toid.len = *buf++;
 207
 208        if ((toksize-=toid.len) < 0)
 209                return(G_BAD_TOK_HEADER);
 210        toid.data = buf;
 211        buf+=toid.len;
 212
 213        if (! g_OID_equal(&toid, mech))
 214                ret = G_WRONG_MECH;
 215
 216   /* G_WRONG_MECH is not returned immediately because it's more important
 217      to return G_BAD_TOK_HEADER if the token header is in fact bad */
 218
 219        if ((toksize-=2) < 0)
 220                return(G_BAD_TOK_HEADER);
 221
 222        if (ret)
 223                return(ret);
 224
 225        if (!ret) {
 226                *buf_in = buf;
 227                *body_size = toksize;
 228        }
 229
 230        return(ret);
 231}
 232
 233EXPORT_SYMBOL_GPL(g_verify_token_header);
 234
 235