1 /*
2  * Copyright (c) 2021 Omar Polo <op@omarpolo.com>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 
17 #include <errno.h>
18 #include <string.h>
19 
20 #include <openssl/bn.h>
21 #include <openssl/pem.h>
22 #include <openssl/x509_vfy.h>
23 #include <openssl/x509v3.h>
24 
25 #include "gmid.h"
26 
27 static sigset_t set;
28 
29 void
30 block_signals(void)
31 {
32 	sigset_t new;
33 
34 	sigemptyset(&new);
35 	sigaddset(&new, SIGHUP);
36 	sigprocmask(SIG_BLOCK, &new, &set);
37 }
38 
39 void
40 unblock_signals(void)
41 {
42 	sigprocmask(SIG_SETMASK, &set, NULL);
43 }
44 
45 int
46 starts_with(const char *str, const char *prefix)
47 {
48 	size_t i;
49 
50 	if (prefix == NULL)
51 		return 0;
52 
53 	for (i = 0; prefix[i] != '\0'; ++i)
54 		if (str[i] != prefix[i])
55 			return 0;
56 	return 1;
57 }
58 
59 int
60 ends_with(const char *str, const char *sufx)
61 {
62 	size_t i, j;
63 
64 	i = strlen(str);
65 	j = strlen(sufx);
66 
67 	if (j > i)
68 		return 0;
69 
70 	i -= j;
71 	for (j = 0; str[i] != '\0'; i++, j++)
72 		if (str[i] != sufx[j])
73 			return 0;
74 	return 1;
75 }
76 
77 ssize_t
78 filesize(int fd)
79 {
80 	ssize_t len;
81 
82 	if ((len = lseek(fd, 0, SEEK_END)) == -1)
83 		return -1;
84 	if (lseek(fd, 0, SEEK_SET) == -1)
85 		return -1;
86 	return len;
87 }
88 
89 char *
90 absolutify_path(const char *path)
91 {
92 	char *wd, *r;
93 
94 	if (*path == '/') {
95 		if ((r = strdup(path)) == NULL)
96 			err(1, "strdup");
97 		return r;
98 	}
99 
100 	wd = getcwd(NULL, 0);
101 	if (asprintf(&r, "%s/%s", wd, path) == -1)
102 		err(1, "asprintf");
103 	free(wd);
104 	return r;
105 }
106 
107 char *
108 xstrdup(const char *s)
109 {
110 	char *d;
111 
112 	if ((d = strdup(s)) == NULL)
113 		err(1, "strdup");
114 	return d;
115 }
116 
117 void
118 gen_certificate(const char *host, const char *certpath, const char *keypath)
119 {
120 	BIGNUM		*e;
121 	EVP_PKEY	*pkey;
122 	RSA		*rsa;
123 	X509		*x509;
124 	X509_NAME	*name;
125 	FILE		*f;
126 	const char	*org = "gmid";
127 
128 	log_notice(NULL,
129 	    "generating new certificate for %s (it could take a while)",
130 	    host);
131 
132 	if ((pkey = EVP_PKEY_new()) == NULL)
133                 fatal("couldn't create a new private key");
134 
135 	if ((rsa = RSA_new()) == NULL)
136 		fatal("couldn't generate rsa");
137 
138 	if ((e = BN_new()) == NULL)
139 		fatal("couldn't allocate a bignum");
140 
141 	BN_set_word(e, 17);
142 	if (!RSA_generate_key_ex(rsa, 4096, e, NULL))
143 		fatal("couldn't generate a rsa key");
144 
145 	if (!EVP_PKEY_assign_RSA(pkey, rsa))
146 		fatal("couldn't assign the key");
147 
148 	if ((x509 = X509_new()) == NULL)
149 		fatal("couldn't generate the X509 certificate");
150 
151 	ASN1_INTEGER_set(X509_get_serialNumber(x509), 1);
152 	X509_gmtime_adj(X509_get_notBefore(x509), 0);
153 	X509_gmtime_adj(X509_get_notAfter(x509), 315360000L); /* 10 years */
154 
155 	if (!X509_set_pubkey(x509, pkey))
156 		fatal("couldn't set the public key");
157 
158 	name = X509_get_subject_name(x509);
159 	if (!X509_NAME_add_entry_by_txt(name, "O", MBSTRING_ASC, org, -1, -1, 0))
160 		fatal("couldn't add N to cert");
161 	if (!X509_NAME_add_entry_by_txt(name, "CN", MBSTRING_ASC, host, -1, -1, 0))
162 		fatal("couldn't add CN to cert");
163 	X509_set_issuer_name(x509, name);
164 
165 	if (!X509_sign(x509, pkey, EVP_sha256()))
166                 fatal("couldn't sign the certificate");
167 
168 	if ((f = fopen(keypath, "w")) == NULL)
169 		fatal("fopen(%s): %s", keypath, strerror(errno));
170 	if (!PEM_write_PrivateKey(f, pkey, NULL, NULL, 0, NULL, NULL))
171 		fatal("couldn't write private key");
172 	fclose(f);
173 
174 	if ((f = fopen(certpath, "w")) == NULL)
175 		fatal("fopen(%s): %s", certpath, strerror(errno));
176 	if (!PEM_write_X509(f, x509))
177 		fatal("couldn't write cert");
178 	fclose(f);
179 
180 	BN_free(e);
181 	X509_free(x509);
182 	RSA_free(rsa);
183 }
184 
185 X509_STORE *
186 load_ca(const char *path)
187 {
188 	FILE		*f = NULL;
189 	X509		*x = NULL;
190 	X509_STORE	*store;
191 
192 	if ((store = X509_STORE_new()) == NULL)
193 		return NULL;
194 
195 	if ((f = fopen(path, "r")) == NULL)
196 		goto err;
197 
198 	if ((x = PEM_read_X509(f, NULL, NULL, NULL)) == NULL)
199 		goto err;
200 
201 	if (X509_check_ca(x) == 0)
202 		goto err;
203 
204 	if (!X509_STORE_add_cert(store, x))
205 		goto err;
206 
207 	X509_free(x);
208 	fclose(f);
209 	return store;
210 
211 err:
212 	X509_STORE_free(store);
213 	if (x != NULL)
214 		X509_free(x);
215 	if (f != NULL)
216 		fclose(f);
217 	return NULL;
218 }
219 
220 int
221 validate_against_ca(X509_STORE *ca, const uint8_t *chain, size_t len)
222 {
223 	X509		*client;
224 	BIO		*m;
225 	X509_STORE_CTX	*ctx = NULL;
226 	int		 ret = 0;
227 
228 	if ((m = BIO_new_mem_buf(chain, len)) == NULL)
229 		return 0;
230 
231 	if ((client = PEM_read_bio_X509(m, NULL, NULL, NULL)) == NULL)
232 		goto end;
233 
234 	if ((ctx = X509_STORE_CTX_new()) == NULL)
235 		goto end;
236 
237 	if (!X509_STORE_CTX_init(ctx, ca, client, NULL))
238 		goto end;
239 
240 	ret = X509_verify_cert(ctx);
241 	fprintf(stderr, "openssl x509_verify_cert: %d\n", ret);
242 
243 end:
244 	BIO_free(m);
245 	if (client != NULL)
246 		X509_free(client);
247 	if (ctx != NULL)
248 		X509_STORE_CTX_free(ctx);
249 	return ret;
250 }