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gss_generic_token.c
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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 <[email protected]>
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 
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 
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 
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 
234