about summary refs log tree commit diff
path: root/credential-cache--daemon.c
blob: ec1271f89ce08b3b117fe09715f61730c7943bea (plain) (blame)
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
290
291
292
293
294
295
296
297
#include "cache.h"
#include "config.h"
#include "tempfile.h"
#include "credential.h"
#include "unix-socket.h"
#include "parse-options.h"

struct credential_cache_entry {
	struct credential item;
	timestamp_t expiration;
};
static struct credential_cache_entry *entries;
static int entries_nr;
static int entries_alloc;

static void cache_credential(struct credential *c, int timeout)
{
	struct credential_cache_entry *e;

	ALLOC_GROW(entries, entries_nr + 1, entries_alloc);
	e = &entries[entries_nr++];

	/* take ownership of pointers */
	memcpy(&e->item, c, sizeof(*c));
	memset(c, 0, sizeof(*c));
	e->expiration = time(NULL) + timeout;
}

static struct credential_cache_entry *lookup_credential(const struct credential *c)
{
	int i;
	for (i = 0; i < entries_nr; i++) {
		struct credential *e = &entries[i].item;
		if (credential_match(c, e))
			return &entries[i];
	}
	return NULL;
}

static void remove_credential(const struct credential *c)
{
	struct credential_cache_entry *e;

	e = lookup_credential(c);
	if (e)
		e->expiration = 0;
}

static timestamp_t check_expirations(void)
{
	static timestamp_t wait_for_entry_until;
	int i = 0;
	timestamp_t now = time(NULL);
	timestamp_t next = TIME_MAX;

	/*
	 * Initially give the client 30 seconds to actually contact us
	 * and store a credential before we decide there's no point in
	 * keeping the daemon around.
	 */
	if (!wait_for_entry_until)
		wait_for_entry_until = now + 30;

	while (i < entries_nr) {
		if (entries[i].expiration <= now) {
			entries_nr--;
			credential_clear(&entries[i].item);
			if (i != entries_nr)
				memcpy(&entries[i], &entries[entries_nr], sizeof(*entries));
			/*
			 * Stick around 30 seconds in case a new credential
			 * shows up (e.g., because we just removed a failed
			 * one, and we will soon get the correct one).
			 */
			wait_for_entry_until = now + 30;
		}
		else {
			if (entries[i].expiration < next)
				next = entries[i].expiration;
			i++;
		}
	}

	if (!entries_nr) {
		if (wait_for_entry_until <= now)
			return 0;
		next = wait_for_entry_until;
	}

	return next - now;
}

static int read_request(FILE *fh, struct credential *c,
			struct strbuf *action, int *timeout)
{
	static struct strbuf item = STRBUF_INIT;
	const char *p;

	strbuf_getline_lf(&item, fh);
	if (!skip_prefix(item.buf, "action=", &p))
		return error("client sent bogus action line: %s", item.buf);
	strbuf_addstr(action, p);

	strbuf_getline_lf(&item, fh);
	if (!skip_prefix(item.buf, "timeout=", &p))
		return error("client sent bogus timeout line: %s", item.buf);
	*timeout = atoi(p);

	if (credential_read(c, fh) < 0)
		return -1;
	return 0;
}

static void serve_one_client(FILE *in, FILE *out)
{
	struct credential c = CREDENTIAL_INIT;
	struct strbuf action = STRBUF_INIT;
	int timeout = -1;

	if (read_request(in, &c, &action, &timeout) < 0)
		/* ignore error */ ;
	else if (!strcmp(action.buf, "get")) {
		struct credential_cache_entry *e = lookup_credential(&c);
		if (e) {
			fprintf(out, "username=%s\n", e->item.username);
			fprintf(out, "password=%s\n", e->item.password);
		}
	}
	else if (!strcmp(action.buf, "exit")) {
		/*
		 * It's important that we clean up our socket first, and then
		 * signal the client only once we have finished the cleanup.
		 * Calling exit() directly does this, because we clean up in
		 * our atexit() handler, and then signal the client when our
		 * process actually ends, which closes the socket and gives
		 * them EOF.
		 */
		exit(0);
	}
	else if (!strcmp(action.buf, "erase"))
		remove_credential(&c);
	else if (!strcmp(action.buf, "store")) {
		if (timeout < 0)
			warning("cache client didn't specify a timeout");
		else if (!c.username || !c.password)
			warning("cache client gave us a partial credential");
		else {
			remove_credential(&c);
			cache_credential(&c, timeout);
		}
	}
	else
		warning("cache client sent unknown action: %s", action.buf);

	credential_clear(&c);
	strbuf_release(&action);
}

static int serve_cache_loop(int fd)
{
	struct pollfd pfd;
	timestamp_t wakeup;

	wakeup = check_expirations();
	if (!wakeup)
		return 0;

	pfd.fd = fd;
	pfd.events = POLLIN;
	if (poll(&pfd, 1, 1000 * wakeup) < 0) {
		if (errno != EINTR)
			die_errno("poll failed");
		return 1;
	}

	if (pfd.revents & POLLIN) {
		int client, client2;
		FILE *in, *out;

		client = accept(fd, NULL, NULL);
		if (client < 0) {
			warning_errno("accept failed");
			return 1;
		}
		client2 = dup(client);
		if (client2 < 0) {
			warning_errno("dup failed");
			close(client);
			return 1;
		}

		in = xfdopen(client, "r");
		out = xfdopen(client2, "w");
		serve_one_client(in, out);
		fclose(in);
		fclose(out);
	}
	return 1;
}

static void serve_cache(const char *socket_path, int debug)
{
	int fd;

	fd = unix_stream_listen(socket_path);
	if (fd < 0)
		die_errno("unable to bind to '%s'", socket_path);

	printf("ok\n");
	fclose(stdout);
	if (!debug) {
		if (!freopen("/dev/null", "w", stderr))
			die_errno("unable to point stderr to /dev/null");
	}

	while (serve_cache_loop(fd))
		; /* nothing */

	close(fd);
}

static const char permissions_advice[] = N_(
"The permissions on your socket directory are too loose; other\n"
"users may be able to read your cached credentials. Consider running:\n"
"\n"
"	chmod 0700 %s");
static void init_socket_directory(const char *path)
{
	struct stat st;
	char *path_copy = xstrdup(path);
	char *dir = dirname(path_copy);

	if (!stat(dir, &st)) {
		if (st.st_mode & 077)
			die(_(permissions_advice), dir);
	} else {
		/*
		 * We must be sure to create the directory with the correct mode,
		 * not just chmod it after the fact; otherwise, there is a race
		 * condition in which somebody can chdir to it, sleep, then try to open
		 * our protected socket.
		 */
		if (safe_create_leading_directories_const(dir) < 0)
			die_errno("unable to create directories for '%s'", dir);
		if (mkdir(dir, 0700) < 0)
			die_errno("unable to mkdir '%s'", dir);
	}

	if (chdir(dir))
		/*
		 * We don't actually care what our cwd is; we chdir here just to
		 * be a friendly daemon and avoid tying up our original cwd.
		 * If this fails, it's OK to just continue without that benefit.
		 */
		;

	free(path_copy);
}

int cmd_main(int argc, const char **argv)
{
	struct tempfile *socket_file;
	const char *socket_path;
	int ignore_sighup = 0;
	static const char *usage[] = {
		"git-credential-cache--daemon [opts] <socket_path>",
		NULL
	};
	int debug = 0;
	const struct option options[] = {
		OPT_BOOL(0, "debug", &debug,
			 N_("print debugging messages to stderr")),
		OPT_END()
	};

	git_config_get_bool("credentialcache.ignoresighup", &ignore_sighup);

	argc = parse_options(argc, argv, NULL, options, usage, 0);
	socket_path = argv[0];

	if (!socket_path)
		usage_with_options(usage, options);

	if (!is_absolute_path(socket_path))
		die("socket directory must be an absolute path");

	init_socket_directory(socket_path);
	socket_file = register_tempfile(socket_path);

	if (ignore_sighup)
		signal(SIGHUP, SIG_IGN);

	serve_cache(socket_path, debug);
	delete_tempfile(&socket_file);

	return 0;
}