1 /*
2 * COPYRIGHT (c) 2008
3 * The Regents of the University of Michigan
4 * ALL RIGHTS RESERVED
5 *
6 * Permission is granted to use, copy, create derivative works
7 * and redistribute this software and such derivative works
8 * for any purpose, so long as the name of The University of
9 * Michigan is not used in any advertising or publicity
10 * pertaining to the use of distribution of this software
11 * without specific, written prior authorization. If the
12 * above copyright notice or any other identification of the
13 * University of Michigan is included in any copy of any
14 * portion of this software, then the disclaimer below must
15 * also be included.
16 *
17 * THIS SOFTWARE IS PROVIDED AS IS, WITHOUT REPRESENTATION
18 * FROM THE UNIVERSITY OF MICHIGAN AS TO ITS FITNESS FOR ANY
19 * PURPOSE, AND WITHOUT WARRANTY BY THE UNIVERSITY OF
20 * MICHIGAN OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING
21 * WITHOUT LIMITATION THE IMPLIED WARRANTIES OF
22 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE
23 * REGENTS OF THE UNIVERSITY OF MICHIGAN SHALL NOT BE LIABLE
24 * FOR ANY DAMAGES, INCLUDING SPECIAL, INDIRECT, INCIDENTAL, OR
25 * CONSEQUENTIAL DAMAGES, WITH RESPECT TO ANY CLAIM ARISING
26 * OUT OF OR IN CONNECTION WITH THE USE OF THE SOFTWARE, EVEN
27 * IF IT HAS BEEN OR IS HEREAFTER ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGES.
29 */
30
31 /*
32 * Copyright (C) 1998 by the FundsXpress, INC.
33 *
34 * All rights reserved.
35 *
36 * Export of this software from the United States of America may require
37 * a specific license from the United States Government. It is the
38 * responsibility of any person or organization contemplating export to
39 * obtain such a license before exporting.
40 *
41 * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
42 * distribute this software and its documentation for any purpose and
43 * without fee is hereby granted, provided that the above copyright
44 * notice appear in all copies and that both that copyright notice and
45 * this permission notice appear in supporting documentation, and that
46 * the name of FundsXpress. not be used in advertising or publicity pertaining
47 * to distribution of the software without specific, written prior
48 * permission. FundsXpress makes no representations about the suitability of
49 * this software for any purpose. It is provided "as is" without express
50 * or implied warranty.
51 *
52 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
53 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
54 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
55 */
56
57 #include <crypto/skcipher.h>
58 #include <linux/err.h>
59 #include <linux/types.h>
60 #include <linux/sunrpc/gss_krb5.h>
61 #include <linux/sunrpc/xdr.h>
62 #include <linux/lcm.h>
63
64 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
65 # define RPCDBG_FACILITY RPCDBG_AUTH
66 #endif
67
68 /*
69 * This is the n-fold function as described in rfc3961, sec 5.1
70 * Taken from MIT Kerberos and modified.
71 */
72
73 static void krb5_nfold(u32 inbits, const u8 *in,
74 u32 outbits, u8 *out)
75 {
76 unsigned long ulcm;
77 int byte, i, msbit;
78
79 /* the code below is more readable if I make these bytes
80 instead of bits */
81
82 inbits >>= 3;
83 outbits >>= 3;
84
85 /* first compute lcm(n,k) */
86 ulcm = lcm(inbits, outbits);
87
88 /* now do the real work */
89
90 memset(out, 0, outbits);
91 byte = 0;
92
93 /* this will end up cycling through k lcm(k,n)/k times, which
94 is correct */
95 for (i = ulcm-1; i >= 0; i--) {
96 /* compute the msbit in k which gets added into this byte */
97 msbit = (
98 /* first, start with the msbit in the first,
99 * unrotated byte */
100 ((inbits << 3) - 1)
101 /* then, for each byte, shift to the right
102 * for each repetition */
103 + (((inbits << 3) + 13) * (i/inbits))
104 /* last, pick out the correct byte within
105 * that shifted repetition */
106 + ((inbits - (i % inbits)) << 3)
107 ) % (inbits << 3);
108
109 /* pull out the byte value itself */
110 byte += (((in[((inbits - 1) - (msbit >> 3)) % inbits] << 8)|
111 (in[((inbits) - (msbit >> 3)) % inbits]))
112 >> ((msbit & 7) + 1)) & 0xff;
113
114 /* do the addition */
115 byte += out[i % outbits];
116 out[i % outbits] = byte & 0xff;
117
118 /* keep around the carry bit, if any */
119 byte >>= 8;
120
121 }
122
123 /* if there's a carry bit left over, add it back in */
124 if (byte) {
125 for (i = outbits - 1; i >= 0; i--) {
126 /* do the addition */
127 byte += out[i];
128 out[i] = byte & 0xff;
129
130 /* keep around the carry bit, if any */
131 byte >>= 8;
132 }
133 }
134 }
135
136 /*
137 * This is the DK (derive_key) function as described in rfc3961, sec 5.1
138 * Taken from MIT Kerberos and modified.
139 */
140
141 u32 krb5_derive_key(const struct gss_krb5_enctype *gk5e,
142 const struct xdr_netobj *inkey,
143 struct xdr_netobj *outkey,
144 const struct xdr_netobj *in_constant,
145 gfp_t gfp_mask)
146 {
147 size_t blocksize, keybytes, keylength, n;
148 unsigned char *inblockdata, *outblockdata, *rawkey;
149 struct xdr_netobj inblock, outblock;
150 struct crypto_sync_skcipher *cipher;
151 u32 ret = EINVAL;
152
153 blocksize = gk5e->blocksize;
154 keybytes = gk5e->keybytes;
155 keylength = gk5e->keylength;
156
157 if ((inkey->len != keylength) || (outkey->len != keylength))
158 goto err_return;
159
160 cipher = crypto_alloc_sync_skcipher(gk5e->encrypt_name, 0, 0);
161 if (IS_ERR(cipher))
162 goto err_return;
163 if (crypto_sync_skcipher_setkey(cipher, inkey->data, inkey->len))
164 goto err_return;
165
166 /* allocate and set up buffers */
167
168 ret = ENOMEM;
169 inblockdata = kmalloc(blocksize, gfp_mask);
170 if (inblockdata == NULL)
171 goto err_free_cipher;
172
173 outblockdata = kmalloc(blocksize, gfp_mask);
174 if (outblockdata == NULL)
175 goto err_free_in;
176
177 rawkey = kmalloc(keybytes, gfp_mask);
178 if (rawkey == NULL)
179 goto err_free_out;
180
181 inblock.data = (char *) inblockdata;
182 inblock.len = blocksize;
183
184 outblock.data = (char *) outblockdata;
185 outblock.len = blocksize;
186
187 /* initialize the input block */
188
189 if (in_constant->len == inblock.len) {
190 memcpy(inblock.data, in_constant->data, inblock.len);
191 } else {
192 krb5_nfold(in_constant->len * 8, in_constant->data,
193 inblock.len * 8, inblock.data);
194 }
195
196 /* loop encrypting the blocks until enough key bytes are generated */
197
198 n = 0;
199 while (n < keybytes) {
200 (*(gk5e->encrypt))(cipher, NULL, inblock.data,
201 outblock.data, inblock.len);
202
203 if ((keybytes - n) <= outblock.len) {
204 memcpy(rawkey + n, outblock.data, (keybytes - n));
205 break;
206 }
207
208 memcpy(rawkey + n, outblock.data, outblock.len);
209 memcpy(inblock.data, outblock.data, outblock.len);
210 n += outblock.len;
211 }
212
213 /* postprocess the key */
214
215 inblock.data = (char *) rawkey;
216 inblock.len = keybytes;
217
218 BUG_ON(gk5e->mk_key == NULL);
219 ret = (*(gk5e->mk_key))(gk5e, &inblock, outkey);
220 if (ret) {
221 dprintk("%s: got %d from mk_key function for '%s'\n",
222 __func__, ret, gk5e->encrypt_name);
223 goto err_free_raw;
224 }
225
226 /* clean memory, free resources and exit */
227
228 ret = 0;
229
230 err_free_raw:
231 kzfree(rawkey);
232 err_free_out:
233 kzfree(outblockdata);
234 err_free_in:
235 kzfree(inblockdata);
236 err_free_cipher:
237 crypto_free_sync_skcipher(cipher);
238 err_return:
239 return ret;
240 }
241
242 #define smask(step) ((1<<step)-1)
243 #define pstep(x, step) (((x)&smask(step))^(((x)>>step)&smask(step)))
244 #define parity_char(x) pstep(pstep(pstep((x), 4), 2), 1)
245
246 static void mit_des_fixup_key_parity(u8 key[8])
247 {
248 int i;
249 for (i = 0; i < 8; i++) {
250 key[i] &= 0xfe;
251 key[i] |= 1^parity_char(key[i]);
252 }
253 }
254
255 /*
256 * This is the des3 key derivation postprocess function
257 */
258 u32 gss_krb5_des3_make_key(const struct gss_krb5_enctype *gk5e,
259 struct xdr_netobj *randombits,
260 struct xdr_netobj *key)
261 {
262 int i;
263 u32 ret = EINVAL;
264
265 if (key->len != 24) {
266 dprintk("%s: key->len is %d\n", __func__, key->len);
267 goto err_out;
268 }
269 if (randombits->len != 21) {
270 dprintk("%s: randombits->len is %d\n",
271 __func__, randombits->len);
272 goto err_out;
273 }
274
275 /* take the seven bytes, move them around into the top 7 bits of the
276 8 key bytes, then compute the parity bits. Do this three times. */
277
278 for (i = 0; i < 3; i++) {
279 memcpy(key->data + i*8, randombits->data + i*7, 7);
280 key->data[i*8+7] = (((key->data[i*8]&1)<<1) |
281 ((key->data[i*8+1]&1)<<2) |
282 ((key->data[i*8+2]&1)<<3) |
283 ((key->data[i*8+3]&1)<<4) |
284 ((key->data[i*8+4]&1)<<5) |
285 ((key->data[i*8+5]&1)<<6) |
286 ((key->data[i*8+6]&1)<<7));
287
288 mit_des_fixup_key_parity(key->data + i*8);
289 }
290 ret = 0;
291 err_out:
292 return ret;
293 }
294
295 /*
296 * This is the aes key derivation postprocess function
297 */
298 u32 gss_krb5_aes_make_key(const struct gss_krb5_enctype *gk5e,
299 struct xdr_netobj *randombits,
300 struct xdr_netobj *key)
301 {
302 u32 ret = EINVAL;
303
304 if (key->len != 16 && key->len != 32) {
305 dprintk("%s: key->len is %d\n", __func__, key->len);
306 goto err_out;
307 }
308 if (randombits->len != 16 && randombits->len != 32) {
309 dprintk("%s: randombits->len is %d\n",
310 __func__, randombits->len);
311 goto err_out;
312 }
313 if (randombits->len != key->len) {
314 dprintk("%s: randombits->len is %d, key->len is %d\n",
315 __func__, randombits->len, key->len);
316 goto err_out;
317 }
318 memcpy(key->data, randombits->data, key->len);
319 ret = 0;
320 err_out:
321 return ret;
322 }