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);