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
13SM_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
32int
33data2hex(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
76static int
77tls_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
120int
121pubkey_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
179int
180dane_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
220int
221dane_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
250int
251dane_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