1 /*
2 * Copyright (c) 2015 Proofpoint, Inc. and its suppliers.
3 * All rights reserved.
4 *
5 * By using this file, you agree to the terms and conditions set
6 * forth in the LICENSE file which can be found at the top level of
7 * the sendmail distribution.
8 *
9 */
10
11 #include <sendmail.h>
12
13 SM_RCSID("@(#)$Id: tls.c,v 8.127 2013-11-27 02:51:11 gshapiro Exp $")
14
15 #if STARTTLS
16 # include <tls.h>
17
18 /*
19 ** DATA2HEX -- create a printable hex string from binary data ("%02X:")
20 **
21 ** Parameters:
22 ** buf -- data
23 ** len -- length of data
24 ** hex -- output buffer
25 ** hlen -- length of output buffer
26 **
27 ** Returns:
28 ** <0: errno
29 ** >0: length of data in hex
30 */
31
32 int
33 data2hex(buf, blen, hex, hlen)
34 unsigned char *buf;
35 int blen;
36 unsigned char *hex;
37 int hlen;
38 {
39 int r, h;
40 static const char hexcodes[] = "0123456789ABCDEF";
41
42 SM_REQUIRE(buf != NULL);
43 SM_REQUIRE(hex != NULL);
44 if (blen * 3 + 2 > hlen)
45 return -ERANGE;
46
47 for (r = 0, h = 0; r < blen && h + 3 < hlen; r++)
48 {
49 hex[h++] = hexcodes[(buf[r] & 0xf0) >> 4];
50 hex[h++] = hexcodes[(buf[r] & 0x0f)];
51 if (r + 1 < blen)
52 hex[h++] = ':';
53 }
54 if (h >= hlen)
55 return -ERANGE;
56 hex[h] = '\0';
57 return h;
58 }
59
60 /*
61 ** TLS_DATA_MD -- calculate MD for data
62 **
63 ** Parameters:
64 ** buf -- data (in and out!)
65 ** len -- length of data
66 ** md -- digest algorithm
67 **
68 ** Returns:
69 ** <=0: cert fp calculation failed
70 ** >0: len of fp
71 **
72 ** Side Effects:
73 ** writes digest to buf
74 */
75
76 static int
tls_data_md(buf,len,md)77 tls_data_md(buf, len, md)
78 unsigned char *buf;
79 int len;
80 const EVP_MD *md;
81 {
82 unsigned int md_len;
83 EVP_MD_CTX *mdctx;
84 unsigned char md_buf[EVP_MAX_MD_SIZE];
85
86 SM_REQUIRE(buf != NULL);
87 SM_REQUIRE(md != NULL);
88 SM_REQUIRE(len >= EVP_MAX_MD_SIZE);
89
90 mdctx = EVP_MD_CTX_create();
91 if (EVP_DigestInit_ex(mdctx, md, NULL) != 1)
92 return -EINVAL;
93 if (EVP_DigestUpdate(mdctx, (void *)buf, len) != 1)
94 return -EINVAL;
95 if (EVP_DigestFinal_ex(mdctx, md_buf, &md_len) != 1)
96 return -EINVAL;
97 EVP_MD_CTX_destroy(mdctx);
98
99 if (md_len > len)
100 return -ERANGE;
101 (void) memcpy(buf, md_buf, md_len);
102 return (int)md_len;
103 }
104
105 #if DANE
106
107 /*
108 ** PUBKEY_FP -- get public key fingerprint
109 **
110 ** Parameters:
111 ** cert -- TLS cert
112 ** mdalg -- name of digest algorithm
113 ** fp -- (pointer to) fingerprint buffer
114 **
115 ** Returns:
116 ** <=0: cert fp calculation failed
117 ** >0: len of fp
118 */
119
120 int
pubkey_fp(cert,mdalg,fp)121 pubkey_fp(cert, mdalg, fp)
122 X509 *cert;
123 const char *mdalg;
124 char **fp;
125 {
126 int len, r;
127 unsigned char *buf, *end;
128 const EVP_MD *md;
129
130 SM_ASSERT(cert != NULL);
131 SM_ASSERT(fp != NULL);
132 SM_ASSERT(mdalg != NULL);
133
134 len = i2d_X509_PUBKEY(X509_get_X509_PUBKEY(cert), NULL);
135
136 /* what's an acceptable upper limit? */
137 if (len <= 0 || len >= 8192)
138 return -EINVAL;
139 if (len < EVP_MAX_MD_SIZE)
140 len = EVP_MAX_MD_SIZE;
141 end = buf = sm_malloc(len);
142 if (NULL == buf)
143 return -ENOMEM;
144
145 if ('\0' == mdalg[0])
146 {
147 r = i2d_X509_PUBKEY(X509_get_X509_PUBKEY(cert), &end);
148 if (r <= 0 || r != len)
149 return -EINVAL;
150 *fp = (char *)buf;
151 return len;
152 }
153
154 md = EVP_get_digestbyname(mdalg);
155 if (NULL == md)
156 return DANE_VRFY_FAIL;
157 len = i2d_X509_PUBKEY(X509_get_X509_PUBKEY(cert), &end);
158 r = tls_data_md(buf, len, md);
159 if (r < 0)
160 sm_free(buf);
161 else
162 *fp = (char *)buf;
163 return r;
164 }
165
166 /*
167 ** DANE_TLSA_CHK -- check whether a TLSA RR is ok to use
168 **
169 ** Parameters:
170 ** rr -- RR
171 ** len -- length of RR
172 ** host -- name of host for RR (only for logging)
173 ** log -- whether to log problems
174 **
175 ** Returns:
176 ** TLSA_*, see tls.h
177 */
178
179 int
dane_tlsa_chk(rr,len,host,log)180 dane_tlsa_chk(rr, len, host, log)
181 const char *rr;
182 int len;
183 const char *host;
184 bool log;
185 {
186 int alg;
187
188 if (len < 4)
189 {
190 if (log && LogLevel > 8)
191 sm_syslog(LOG_WARNING, NOQID,
192 "TLSA=%s, len=%d, status=bogus",
193 host, len);
194 return TLSA_BOGUS;
195 }
196 SM_ASSERT(rr != NULL);
197
198 alg = (int)rr[2];
199 if ((int)rr[0] == 3 && (int)rr[1] == 1 && (alg >= 0 || alg <= 2))
200 return alg;
201 if (log && LogLevel > 9)
202 sm_syslog(LOG_NOTICE, NOQID,
203 "TLSA=%s, type=%d-%d-%d:%02x, status=unsupported",
204 host, (int)rr[0], (int)rr[1], (int)rr[2],
205 (int)rr[3]);
206 return TLSA_UNSUPP;
207 }
208
209 /*
210 ** DANE_TLSA_CLR -- clear data in a dane_tlsa structure (for use)
211 **
212 ** Parameters:
213 ** dane_tlsa -- dane_tlsa to clear
214 **
215 ** Returns:
216 ** 1 if NULL
217 ** 0 if ok
218 */
219
220 int
dane_tlsa_clr(dane_tlsa)221 dane_tlsa_clr(dane_tlsa)
222 dane_tlsa_P dane_tlsa;
223 {
224 int i;
225
226 if (dane_tlsa == NULL)
227 return 1;
228 for (i = 0; i < dane_tlsa->dane_tlsa_n; i++)
229 {
230 SM_FREE(dane_tlsa->dane_tlsa_rr[i]);
231 dane_tlsa->dane_tlsa_len[i] = 0;
232 }
233 SM_FREE(dane_tlsa->dane_tlsa_sni);
234 memset(dane_tlsa, '\0', sizeof(*dane_tlsa));
235 return 0;
236
237 }
238
239 /*
240 ** DANE_TLSA_FREE -- free a dane_tlsa structure
241 **
242 ** Parameters:
243 ** dane_tlsa -- dane_tlsa to free
244 **
245 ** Returns:
246 ** 0 if ok
247 ** 1 if NULL
248 */
249
250 int
dane_tlsa_free(dane_tlsa)251 dane_tlsa_free(dane_tlsa)
252 dane_tlsa_P dane_tlsa;
253 {
254 if (dane_tlsa == NULL)
255 return 1;
256 dane_tlsa_clr(dane_tlsa);
257 SM_FREE(dane_tlsa);
258 return 0;
259
260 }
261 #endif /* DANE */
262
263 #endif /* STARTTLS */
264