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/string.h>
  37 #include <linux/sunrpc/sched.h>
  38 #include <linux/sunrpc/gss_asn1.h>
  39
  40
  41 #if IS_ENABLED(CONFIG_SUNRPC_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
  58 0x60                            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
  68 For the purposes of this abstraction, the token "header" consists of
  69 the sequence tag and length octets, the mech OID DER encoding, and the
  70 first two inner bytes, which indicate the token type.  The token
  71 "body" consists of everything else.
  72
  73 */
  74
  75 static int
  76 der_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
  95 static void
  96 der_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
 117 static int
 118 der_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
 146 int
 147 g_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
 154 EXPORT_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
 159 void
 160 g_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
 169 EXPORT_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  */
 179 u32
 180 g_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
 233 EXPORT_SYMBOL_GPL(g_verify_token_header);