1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2008 Isilon Inc http://www.isilon.com/
5 * Authors: Doug Rabson <dfr@rabson.org>
6 * Developed with Red Inc: Alfred Perlstein <alfred@freebsd.org>
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30 #include <sys/param.h>
31 #include <sys/malloc.h>
32 #include <sys/kobj.h>
33 #include <sys/mbuf.h>
34 #include <sys/sysctl.h>
35
36 #include <kgssapi/gssapi.h>
37 #include <kgssapi/gssapi_impl.h>
38
39 #include "kcrypto.h"
40
41 static struct krb5_encryption_class *krb5_encryption_classes[] = {
42 &krb5_aes128_encryption_class,
43 &krb5_aes256_encryption_class,
44 NULL
45 };
46
47 struct krb5_encryption_class *
krb5_find_encryption_class(int etype)48 krb5_find_encryption_class(int etype)
49 {
50 int i;
51
52 for (i = 0; krb5_encryption_classes[i]; i++) {
53 if (krb5_encryption_classes[i]->ec_type == etype)
54 return (krb5_encryption_classes[i]);
55 }
56 return (NULL);
57 }
58
59 struct krb5_key_state *
krb5_create_key(const struct krb5_encryption_class * ec)60 krb5_create_key(const struct krb5_encryption_class *ec)
61 {
62 struct krb5_key_state *ks;
63
64 ks = malloc(sizeof(struct krb5_key_state), M_GSSAPI, M_WAITOK);
65 ks->ks_class = ec;
66 refcount_init(&ks->ks_refs, 1);
67 ks->ks_key = malloc(ec->ec_keylen, M_GSSAPI, M_WAITOK);
68 ec->ec_init(ks);
69
70 return (ks);
71 }
72
73 void
krb5_free_key(struct krb5_key_state * ks)74 krb5_free_key(struct krb5_key_state *ks)
75 {
76
77 if (refcount_release(&ks->ks_refs)) {
78 ks->ks_class->ec_destroy(ks);
79 bzero(ks->ks_key, ks->ks_class->ec_keylen);
80 free(ks->ks_key, M_GSSAPI);
81 free(ks, M_GSSAPI);
82 }
83 }
84
85 static size_t
gcd(size_t a,size_t b)86 gcd(size_t a, size_t b)
87 {
88
89 if (b == 0)
90 return (a);
91 return gcd(b, a % b);
92 }
93
94 static size_t
lcm(size_t a,size_t b)95 lcm(size_t a, size_t b)
96 {
97 return ((a * b) / gcd(a, b));
98 }
99
100 /*
101 * Rotate right 13 of a variable precision number in 'in', storing the
102 * result in 'out'. The number is assumed to be big-endian in memory
103 * representation.
104 */
105 static void
krb5_rotate_right_13(uint8_t * out,uint8_t * in,size_t numlen)106 krb5_rotate_right_13(uint8_t *out, uint8_t *in, size_t numlen)
107 {
108 uint32_t carry;
109 size_t i;
110
111 /*
112 * Special case when numlen == 1. A rotate right 13 of a
113 * single byte number changes to a rotate right 5.
114 */
115 if (numlen == 1) {
116 carry = in[0] >> 5;
117 out[0] = (in[0] << 3) | carry;
118 return;
119 }
120
121 carry = ((in[numlen - 2] & 31) << 8) | in[numlen - 1];
122 for (i = 2; i < numlen; i++) {
123 out[i] = ((in[i - 2] & 31) << 3) | (in[i - 1] >> 5);
124 }
125 out[1] = ((carry & 31) << 3) | (in[0] >> 5);
126 out[0] = carry >> 5;
127 }
128
129 /*
130 * Add two variable precision numbers in big-endian representation
131 * using ones-complement arithmetic.
132 */
133 static void
krb5_ones_complement_add(uint8_t * out,const uint8_t * in,size_t len)134 krb5_ones_complement_add(uint8_t *out, const uint8_t *in, size_t len)
135 {
136 int n, i;
137
138 /*
139 * First calculate the 2s complement sum, remembering the
140 * carry.
141 */
142 n = 0;
143 for (i = len - 1; i >= 0; i--) {
144 n = out[i] + in[i] + n;
145 out[i] = n;
146 n >>= 8;
147 }
148 /*
149 * Then add back the carry.
150 */
151 for (i = len - 1; n && i >= 0; i--) {
152 n = out[i] + n;
153 out[i] = n;
154 n >>= 8;
155 }
156 }
157
158 static void
krb5_n_fold(uint8_t * out,size_t outlen,const uint8_t * in,size_t inlen)159 krb5_n_fold(uint8_t *out, size_t outlen, const uint8_t *in, size_t inlen)
160 {
161 size_t tmplen;
162 uint8_t *tmp;
163 size_t i;
164 uint8_t *p;
165
166 tmplen = lcm(inlen, outlen);
167 tmp = malloc(tmplen, M_GSSAPI, M_WAITOK);
168
169 bcopy(in, tmp, inlen);
170 for (i = inlen, p = tmp; i < tmplen; i += inlen, p += inlen) {
171 krb5_rotate_right_13(p + inlen, p, inlen);
172 }
173 bzero(out, outlen);
174 for (i = 0, p = tmp; i < tmplen; i += outlen, p += outlen) {
175 krb5_ones_complement_add(out, p, outlen);
176 }
177 free(tmp, M_GSSAPI);
178 }
179
180 struct krb5_key_state *
krb5_derive_key(struct krb5_key_state * inkey,void * constant,size_t constantlen)181 krb5_derive_key(struct krb5_key_state *inkey,
182 void *constant, size_t constantlen)
183 {
184 struct krb5_key_state *dk;
185 const struct krb5_encryption_class *ec = inkey->ks_class;
186 uint8_t *folded;
187 uint8_t *bytes, *p, *q;
188 struct mbuf *m;
189 int randomlen, i;
190
191 /*
192 * Expand the constant to blocklen bytes.
193 */
194 folded = malloc(ec->ec_blocklen, M_GSSAPI, M_WAITOK);
195 krb5_n_fold(folded, ec->ec_blocklen, constant, constantlen);
196
197 /*
198 * Generate enough bytes for keybits rounded up to a multiple
199 * of blocklen.
200 */
201 randomlen = roundup(ec->ec_keybits / 8, ec->ec_blocklen);
202 bytes = malloc(randomlen, M_GSSAPI, M_WAITOK);
203 MGET(m, M_WAITOK, MT_DATA);
204 m->m_len = ec->ec_blocklen;
205 for (i = 0, p = bytes, q = folded; i < randomlen;
206 q = p, i += ec->ec_blocklen, p += ec->ec_blocklen) {
207 bcopy(q, m->m_data, ec->ec_blocklen);
208 krb5_encrypt(inkey, m, 0, ec->ec_blocklen, NULL, 0);
209 bcopy(m->m_data, p, ec->ec_blocklen);
210 }
211 m_free(m);
212
213 dk = krb5_create_key(ec);
214 krb5_random_to_key(dk, bytes);
215
216 free(folded, M_GSSAPI);
217 free(bytes, M_GSSAPI);
218
219 return (dk);
220 }
221
222 static struct krb5_key_state *
krb5_get_usage_key(struct krb5_key_state * basekey,int usage,int which)223 krb5_get_usage_key(struct krb5_key_state *basekey, int usage, int which)
224 {
225 const struct krb5_encryption_class *ec = basekey->ks_class;
226
227 if (ec->ec_flags & EC_DERIVED_KEYS) {
228 uint8_t constant[5];
229
230 constant[0] = usage >> 24;
231 constant[1] = usage >> 16;
232 constant[2] = usage >> 8;
233 constant[3] = usage;
234 constant[4] = which;
235 return (krb5_derive_key(basekey, constant, 5));
236 } else {
237 refcount_acquire(&basekey->ks_refs);
238 return (basekey);
239 }
240 }
241
242 struct krb5_key_state *
krb5_get_encryption_key(struct krb5_key_state * basekey,int usage)243 krb5_get_encryption_key(struct krb5_key_state *basekey, int usage)
244 {
245
246 return (krb5_get_usage_key(basekey, usage, 0xaa));
247 }
248
249 struct krb5_key_state *
krb5_get_integrity_key(struct krb5_key_state * basekey,int usage)250 krb5_get_integrity_key(struct krb5_key_state *basekey, int usage)
251 {
252
253 return (krb5_get_usage_key(basekey, usage, 0x55));
254 }
255
256 struct krb5_key_state *
krb5_get_checksum_key(struct krb5_key_state * basekey,int usage)257 krb5_get_checksum_key(struct krb5_key_state *basekey, int usage)
258 {
259
260 return (krb5_get_usage_key(basekey, usage, 0x99));
261 }
262