Pass full argument list to mood parsers.
[paraslash.git] / crypt.c
1 /*
2 * Copyright (C) 2005-2009 Andre Noll <maan@systemlinux.org>
3 *
4 * Licensed under the GPL v2. For licencing details see COPYING.
5 */
6
7 /** \file crypt.c openssl-based RSA encryption/decryption routines */
8
9 #include <dirent.h>
10 #include <sys/types.h>
11 #include <sys/socket.h>
12 #include <openssl/rand.h>
13 #include <openssl/err.h>
14 #include <openssl/rc4.h>
15
16 #include "para.h"
17 #include "error.h"
18 #include "string.h"
19 #include "crypt.h"
20 #include "fd.h"
21 /**
22 * Fill a buffer with random content.
23 *
24 * \param buf The buffer to fill.
25 * \param num The size of \a buf in bytes.
26 *
27 * This function puts \a num cryptographically strong pseudo-random bytes into
28 * buf. If libssl can not guarantee an unpredictable byte sequence (for example
29 * because the PRNG has not been seeded with enough randomness) the function
30 * logs an error message and calls exit().
31 */
32 void get_random_bytes_or_die(unsigned char *buf, int num)
33 {
34 unsigned long err;
35
36 /* RAND_bytes() returns 1 on success, 0 otherwise. */
37 if (RAND_bytes(buf, num) == 1)
38 return;
39 err = ERR_get_error();
40 PARA_EMERG_LOG("%s\n", ERR_reason_error_string(err));
41 exit(EXIT_FAILURE);
42 }
43
44 /**
45 * Seed pseudo random number generators.
46 *
47 * This function reads 64 bytes from /dev/urandom and adds them to the SSL
48 * PRNG. It also seeds the PRNG used by random() with a random seed obtained
49 * from SSL. If /dev/random could not be read, an error message is logged and
50 * the function calls exit().
51 *
52 * \sa RAND_load_file(3), \ref get_random_bytes_or_die(), srandom(3),
53 * random(3), \ref para_random().
54 */
55 void init_random_seed_or_die(void)
56 {
57 int seed, ret = RAND_load_file("/dev/urandom", 64);
58
59 if (ret != 64) {
60 PARA_EMERG_LOG("could not seed PRNG (ret = %d)\n", ret);
61 exit(EXIT_FAILURE);
62 }
63 get_random_bytes_or_die((unsigned char *)&seed, sizeof(seed));
64 srandom(seed);
65 }
66
67 static EVP_PKEY *load_key(const char *file, int private)
68 {
69 BIO *key;
70 EVP_PKEY *pkey = NULL;
71
72 key = BIO_new(BIO_s_file());
73 if (!key)
74 return NULL;
75 if (BIO_read_filename(key, file) > 0) {
76 if (private == LOAD_PRIVATE_KEY)
77 pkey = PEM_read_bio_PrivateKey(key, NULL, NULL, NULL);
78 else
79 pkey = PEM_read_bio_PUBKEY(key, NULL, NULL, NULL);
80 }
81 BIO_free(key);
82 return pkey;
83 }
84
85 /**
86 * read an RSA key from a file
87 *
88 * \param key_file the file containing the key
89 * \param rsa RSA structure is returned here
90 * \param private if non-zero, read the private key, otherwise the public key
91 *
92 * \return The size of the RSA key on success, negative on errors.
93 *
94 * \sa openssl(1), rsa(1).
95 */
96 int get_rsa_key(char *key_file, RSA **rsa, int private)
97 {
98 EVP_PKEY *key = load_key(key_file, private);
99
100 if (!key)
101 return (private == LOAD_PRIVATE_KEY)? -E_PRIVATE_KEY
102 : -E_PUBLIC_KEY;
103 *rsa = EVP_PKEY_get1_RSA(key);
104 EVP_PKEY_free(key);
105 if (!*rsa)
106 return -E_RSA;
107 return RSA_size(*rsa);
108 }
109
110 /**
111 * free an RSA structure
112 *
113 * \param rsa pointer to the RSA struct to free
114 *
115 * This must be called for any key obtained by get_rsa_key().
116 */
117 void rsa_free(RSA *rsa)
118 {
119 if (rsa)
120 RSA_free(rsa);
121 }
122
123 /**
124 * decrypt a buffer using an RSA key
125 *
126 * \param key_file full path of the rsa key
127 * \param outbuf the output buffer
128 * \param inbuf the encrypted input buffer
129 * \param rsa_inlen the length of \a inbuf
130 *
131 * The \a outbuf must be large enough to hold at least \a rsa_inlen bytes.
132 *
133 * \return The size of the recovered plaintext on success, negative on errors.
134 *
135 * \sa RSA_private_decrypt(3)
136 **/
137 int para_decrypt_buffer(char *key_file, unsigned char *outbuf, unsigned char *inbuf,
138 unsigned rsa_inlen)
139 {
140 RSA *rsa;
141 int ret, inlen = rsa_inlen;
142
143 if (inlen < 0)
144 return -E_RSA;
145 ret = get_rsa_key(key_file, &rsa, LOAD_PRIVATE_KEY);
146 if (ret < 0)
147 return ret;
148 ret = RSA_private_decrypt(inlen, inbuf, outbuf, rsa, RSA_PKCS1_OAEP_PADDING);
149 rsa_free(rsa);
150 return (ret > 0)? ret : -E_DECRYPT;
151 }
152
153 /**
154 * encrypt a buffer using an RSA key
155 *
156 * \param rsa: public rsa key
157 * \param inbuf the input buffer
158 * \param len the length of \a inbuf
159 * \param outbuf the output buffer
160 *
161 * \return The size of the encrypted data on success, negative on errors
162 *
163 * \sa RSA_public_encrypt(3)
164 */
165 int para_encrypt_buffer(RSA *rsa, unsigned char *inbuf,
166 unsigned len, unsigned char *outbuf)
167 {
168 int ret, flen = len; /* RSA_public_encrypt expects a signed int */
169
170 if (flen < 0)
171 return -E_ENCRYPT;
172 ret = RSA_public_encrypt(flen, inbuf, outbuf, rsa, RSA_PKCS1_OAEP_PADDING);
173 return ret < 0? -E_ENCRYPT : ret;
174 }
175
176 /**
177 * Encrypt and send a buffer.
178 *
179 * \param rc4c The rc4 crypt context.
180 * \param buf The buffer to send.
181 * \param len The size of \a buf in bytes.
182 *
183 * \return The return value of the underyling call to write_all().
184 *
185 * \sa \ref write_all(), RC4(3).
186 */
187 int rc4_send_bin_buffer(struct rc4_context *rc4c, const char *buf, size_t len)
188 {
189 int ret;
190 unsigned char *tmp;
191
192 assert(len);
193 tmp = para_malloc(len);
194 RC4(&rc4c->send_key, len, (const unsigned char *)buf, tmp);
195 ret = write_all(rc4c->fd, (char *)tmp, &len);
196 free(tmp);
197 return ret;
198 }
199
200 /**
201 * Encrypt and send a \p NULL-terminated buffer.
202 *
203 * \param rc4c The rc4 crypt context.
204 * \param buf The buffer to send.
205 *
206 * \return The return value of the underyling call to rc4_send_bin_buffer().
207 */
208 int rc4_send_buffer(struct rc4_context *rc4c, const char *buf)
209 {
210 return rc4_send_bin_buffer(rc4c, buf, strlen(buf));
211 }
212
213 /**
214 * Format, encrypt and send a buffer.
215 *
216 * \param rc4c The rc4 crypt context.
217 * \param fmt A format string.
218 *
219 * \return The return value of the underyling call to rc4_send_buffer().
220 */
221 __printf_2_3 int rc4_send_va_buffer(struct rc4_context *rc4c, const char *fmt, ...)
222 {
223 char *msg;
224 int ret;
225
226 PARA_VSPRINTF(fmt, msg);
227 ret = rc4_send_buffer(rc4c, msg);
228 free(msg);
229 return ret;
230 }
231
232 /**
233 * Receive a buffer and decrypt it.
234 *
235 * \param rc4c The rc4 crypt context.
236 * \param buf The buffer to write the decrypted data to.
237 * \param size The size of \a buf.
238 *
239 * \return The number of bytes received on success, negative on errors, zero if
240 * the peer has performed an orderly shutdown.
241 *
242 * \sa recv(2), RC4(3).
243 */
244 int rc4_recv_bin_buffer(struct rc4_context *rc4c, char *buf, size_t size)
245 {
246 unsigned char *tmp = para_malloc(size);
247 ssize_t ret = recv(rc4c->fd, tmp, size, 0);
248
249 if (ret > 0)
250 RC4(&rc4c->recv_key, ret, tmp, (unsigned char *)buf);
251 else if (ret < 0)
252 ret = -ERRNO_TO_PARA_ERROR(errno);
253 free(tmp);
254 return ret;
255 }
256
257 /**
258 * Receive a buffer, decrypt it and write terminating NULL byte.
259 *
260 * \param rc4c The rc4 crypt context.
261 * \param buf The buffer to write the decrypted data to.
262 * \param size The size of \a buf.
263 *
264 * Read at most \a size - 1 bytes from file descriptor given by \a rc4c,
265 * decrypt the received data and write a NULL byte at the end of the decrypted
266 * data.
267 *
268 * \return The return value of the underlying call to \ref
269 * rc4_recv_bin_buffer().
270 */
271 int rc4_recv_buffer(struct rc4_context *rc4c, char *buf, size_t size)
272 {
273 int n;
274
275 assert(size);
276 n = rc4_recv_bin_buffer(rc4c, buf, size - 1);
277 if (n >= 0)
278 buf[n] = '\0';
279 else
280 *buf = '\0';
281 return n;
282 }