summaryrefslogtreecommitdiff
path: root/authenticate.c
blob: d2b74cd8ec38191dc126422e927778dc2365964f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
/* -*- c-file-style: "linux"; -*-
   
   Copyright (C) 1998-2000 by Andrew Tridgell 
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

/* support rsync authentication */
#include "rsync.h"

/***************************************************************************
encode a buffer using base64 - simple and slow algorithm. null terminates
the result.
  ***************************************************************************/
static void base64_encode(char *buf, int len, char *out)
{
	char *b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
	int bit_offset, byte_offset, idx, i;
	unsigned char *d = (unsigned char *)buf;
	int bytes = (len*8 + 5)/6;

	memset(out, 0, bytes+1);

	for (i=0;i<bytes;i++) {
		byte_offset = (i*6)/8;
		bit_offset = (i*6)%8;
		if (bit_offset < 3) {
			idx = (d[byte_offset] >> (2-bit_offset)) & 0x3F;
		} else {
			idx = (d[byte_offset] << (bit_offset-2)) & 0x3F;
			if (byte_offset+1 < len) {
				idx |= (d[byte_offset+1] >> (8-(bit_offset-2)));
			}
		}
		out[i] = b64[idx];
	}
}

/* create a 16 byte challenge buffer */
static void gen_challenge(char *addr, char *challenge)
{
	char input[32];
	struct timeval tv;

	memset(input, 0, sizeof(input));

	strlcpy((char *)input, addr, 17);
	sys_gettimeofday(&tv);
	SIVAL(input, 16, tv.tv_sec);
	SIVAL(input, 20, tv.tv_usec);
	SIVAL(input, 24, getpid());

	sum_init();
	sum_update(input, sizeof(input));
	sum_end(challenge);
}


/* return the secret for a user from the sercret file. maximum length
   is len. null terminate it */
static int get_secret(int module, char *user, char *secret, int len)
{
	char *fname = lp_secrets_file(module);
	int fd, found=0;
	char line[MAXPATHLEN];
	char *p, *pass=NULL;
	STRUCT_STAT st;
	int ok = 1;
	extern int am_root;

	if (!fname || !*fname) return 0;

	fd = open(fname,O_RDONLY);
	if (fd == -1) return 0;

	if (do_stat(fname, &st) == -1) {
		rsyserr(FERROR, errno, "stat(%s)", fname);
		ok = 0;
	} else if (lp_strict_modes(module)) {
		if ((st.st_mode & 06) != 0) {
			rprintf(FERROR,"secrets file must not be other-accessible (see strict modes option)\n");
			ok = 0;
		} else if (am_root && (st.st_uid != 0)) {
			rprintf(FERROR,"secrets file must be owned by root when running as root (see strict modes)\n");
			ok = 0;
		}
	}
	if (!ok) {
		rprintf(FERROR,"continuing without secrets file\n");
		close(fd);
		return 0;
	}

	while (!found) {
		int i = 0;
		memset(line, 0, sizeof line);
		while ((size_t) i < (sizeof(line)-1)) {
			if (read(fd, &line[i], 1) != 1) {
				memset(line, 0, sizeof(line));
				close(fd);
				return 0;
			}
			if (line[i] == '\r') continue;
			if (line[i] == '\n') break;
			i++;
		}
		line[i] = 0;
		if (line[0] == '#') continue;
		p = strchr(line,':');
		if (!p) continue;
		*p = 0;
		if (strcmp(user, line)) continue;
		pass = p+1;
		found = 1;
	}

	close(fd);
	if (!found) return 0;

	strlcpy(secret, pass, len);
	return 1;
}

static char *getpassf(char *filename)
{
	char buffer[100];
	int fd=0;
	STRUCT_STAT st;
	int ok = 1;
	extern int am_root;
	char *envpw=getenv("RSYNC_PASSWORD");

	if (!filename) return NULL;

	if ( (fd=open(filename,O_RDONLY)) == -1) {
		rsyserr(FERROR, errno, "could not open password file \"%s\"",filename);
		if (envpw) rprintf(FERROR,"falling back to RSYNC_PASSWORD environment variable.\n");	
		return NULL;
	}
	
	if (do_stat(filename, &st) == -1) {
		rsyserr(FERROR, errno, "stat(%s)", filename);
		ok = 0;
	} else if ((st.st_mode & 06) != 0) {
		rprintf(FERROR,"password file must not be other-accessible\n");
		ok = 0;
	} else if (am_root && (st.st_uid != 0)) {
		rprintf(FERROR,"password file must be owned by root when running as root\n");
		ok = 0;
	}
	if (!ok) {
		rprintf(FERROR,"continuing without password file\n");
		if (envpw) rprintf(FERROR,"using RSYNC_PASSWORD environment variable.\n");
		close(fd);
		return NULL;
	}

	if (envpw) rprintf(FERROR,"RSYNC_PASSWORD environment variable ignored\n");

	buffer[sizeof(buffer)-1]='\0';
	if (read(fd,buffer,sizeof(buffer)-1) > 0)
	{
		char *p = strtok(buffer,"\n\r");
		close(fd);
		if (p) p = strdup(p);
		return p;
	}	

	return NULL;
}

/* generate a 16 byte hash from a password and challenge */
static void generate_hash(char *in, char *challenge, char *out)
{
	char buf[16];

	sum_init();
	sum_update(in, strlen(in));
	sum_update(challenge, strlen(challenge));
	sum_end(buf);

	base64_encode(buf, 16, out);
}

/* possible negotiate authentication with the client. Use "leader" to
   start off the auth if necessary 

   return NULL if authentication failed

   return "" if anonymous access

   otherwise return username
*/
char *auth_server(int fd, int module, char *addr, char *leader)
{
	char *users = lp_auth_users(module);
	char challenge[16];
	char b64_challenge[30];
	char line[MAXPATHLEN];
	static char user[100];
	char secret[100];
	char pass[30];
	char pass2[30];
	char *tok;

	/* if no auth list then allow anyone in! */
	if (!users || !*users) return "";

	gen_challenge(addr, challenge);
	
	base64_encode(challenge, 16, b64_challenge);

	io_printf(fd,"%s%s\n", leader, b64_challenge);

	if (!read_line(fd, line, sizeof(line)-1)) {
		return NULL;
	}

	memset(user, 0, sizeof(user));
	memset(pass, 0, sizeof(pass));

	if (sscanf(line,"%99s %29s", user, pass) != 2) {
		return NULL;
	}
	
	users = strdup(users);
	if (!users) return NULL;

	for (tok=strtok(users," ,\t"); tok; tok = strtok(NULL," ,\t")) {
		if (fnmatch(tok, user, 0) == 0) break;
	}
	free(users);

	if (!tok) {
		return NULL;
	}
	
	memset(secret, 0, sizeof(secret));
	if (!get_secret(module, user, secret, sizeof(secret)-1)) {
		memset(secret, 0, sizeof(secret));
		return NULL;
	}

	generate_hash(secret, b64_challenge, pass2);
	memset(secret, 0, sizeof(secret));
	
	if (strcmp(pass, pass2) == 0)
		return user;

	return NULL;
}


void auth_client(int fd, char *user, char *challenge)
{
	char *pass;
	char pass2[30];
	extern char *password_file;

	if (!user || !*user) return;

	if (!(pass=getpassf(password_file)) && !(pass=getenv("RSYNC_PASSWORD"))) {
		/* XXX: cyeoh says that getpass is deprecated, because
		   it may return a truncated password on some systems,
		   and it is not in the LSB. */
		pass = getpass("Password: ");
	}

	if (!pass || !*pass) {
		pass = "";
	}

	generate_hash(pass, challenge, pass2);
	io_printf(fd, "%s %s\n", user, pass2);
}