Merge branch 'nd/worktree-lock' into maint
[git] / credential-cache--daemon.c
1 #include "cache.h"
2 #include "tempfile.h"
3 #include "credential.h"
4 #include "unix-socket.h"
5 #include "parse-options.h"
6
7 static struct tempfile socket_file;
8
9 struct credential_cache_entry {
10         struct credential item;
11         unsigned long expiration;
12 };
13 static struct credential_cache_entry *entries;
14 static int entries_nr;
15 static int entries_alloc;
16
17 static void cache_credential(struct credential *c, int timeout)
18 {
19         struct credential_cache_entry *e;
20
21         ALLOC_GROW(entries, entries_nr + 1, entries_alloc);
22         e = &entries[entries_nr++];
23
24         /* take ownership of pointers */
25         memcpy(&e->item, c, sizeof(*c));
26         memset(c, 0, sizeof(*c));
27         e->expiration = time(NULL) + timeout;
28 }
29
30 static struct credential_cache_entry *lookup_credential(const struct credential *c)
31 {
32         int i;
33         for (i = 0; i < entries_nr; i++) {
34                 struct credential *e = &entries[i].item;
35                 if (credential_match(c, e))
36                         return &entries[i];
37         }
38         return NULL;
39 }
40
41 static void remove_credential(const struct credential *c)
42 {
43         struct credential_cache_entry *e;
44
45         e = lookup_credential(c);
46         if (e)
47                 e->expiration = 0;
48 }
49
50 static int check_expirations(void)
51 {
52         static unsigned long wait_for_entry_until;
53         int i = 0;
54         unsigned long now = time(NULL);
55         unsigned long next = (unsigned long)-1;
56
57         /*
58          * Initially give the client 30 seconds to actually contact us
59          * and store a credential before we decide there's no point in
60          * keeping the daemon around.
61          */
62         if (!wait_for_entry_until)
63                 wait_for_entry_until = now + 30;
64
65         while (i < entries_nr) {
66                 if (entries[i].expiration <= now) {
67                         entries_nr--;
68                         credential_clear(&entries[i].item);
69                         if (i != entries_nr)
70                                 memcpy(&entries[i], &entries[entries_nr], sizeof(*entries));
71                         /*
72                          * Stick around 30 seconds in case a new credential
73                          * shows up (e.g., because we just removed a failed
74                          * one, and we will soon get the correct one).
75                          */
76                         wait_for_entry_until = now + 30;
77                 }
78                 else {
79                         if (entries[i].expiration < next)
80                                 next = entries[i].expiration;
81                         i++;
82                 }
83         }
84
85         if (!entries_nr) {
86                 if (wait_for_entry_until <= now)
87                         return 0;
88                 next = wait_for_entry_until;
89         }
90
91         return next - now;
92 }
93
94 static int read_request(FILE *fh, struct credential *c,
95                         struct strbuf *action, int *timeout) {
96         static struct strbuf item = STRBUF_INIT;
97         const char *p;
98
99         strbuf_getline_lf(&item, fh);
100         if (!skip_prefix(item.buf, "action=", &p))
101                 return error("client sent bogus action line: %s", item.buf);
102         strbuf_addstr(action, p);
103
104         strbuf_getline_lf(&item, fh);
105         if (!skip_prefix(item.buf, "timeout=", &p))
106                 return error("client sent bogus timeout line: %s", item.buf);
107         *timeout = atoi(p);
108
109         if (credential_read(c, fh) < 0)
110                 return -1;
111         return 0;
112 }
113
114 static void serve_one_client(FILE *in, FILE *out)
115 {
116         struct credential c = CREDENTIAL_INIT;
117         struct strbuf action = STRBUF_INIT;
118         int timeout = -1;
119
120         if (read_request(in, &c, &action, &timeout) < 0)
121                 /* ignore error */ ;
122         else if (!strcmp(action.buf, "get")) {
123                 struct credential_cache_entry *e = lookup_credential(&c);
124                 if (e) {
125                         fprintf(out, "username=%s\n", e->item.username);
126                         fprintf(out, "password=%s\n", e->item.password);
127                 }
128         }
129         else if (!strcmp(action.buf, "exit")) {
130                 /*
131                  * It's important that we clean up our socket first, and then
132                  * signal the client only once we have finished the cleanup.
133                  * Calling exit() directly does this, because we clean up in
134                  * our atexit() handler, and then signal the client when our
135                  * process actually ends, which closes the socket and gives
136                  * them EOF.
137                  */
138                 exit(0);
139         }
140         else if (!strcmp(action.buf, "erase"))
141                 remove_credential(&c);
142         else if (!strcmp(action.buf, "store")) {
143                 if (timeout < 0)
144                         warning("cache client didn't specify a timeout");
145                 else if (!c.username || !c.password)
146                         warning("cache client gave us a partial credential");
147                 else {
148                         remove_credential(&c);
149                         cache_credential(&c, timeout);
150                 }
151         }
152         else
153                 warning("cache client sent unknown action: %s", action.buf);
154
155         credential_clear(&c);
156         strbuf_release(&action);
157 }
158
159 static int serve_cache_loop(int fd)
160 {
161         struct pollfd pfd;
162         unsigned long wakeup;
163
164         wakeup = check_expirations();
165         if (!wakeup)
166                 return 0;
167
168         pfd.fd = fd;
169         pfd.events = POLLIN;
170         if (poll(&pfd, 1, 1000 * wakeup) < 0) {
171                 if (errno != EINTR)
172                         die_errno("poll failed");
173                 return 1;
174         }
175
176         if (pfd.revents & POLLIN) {
177                 int client, client2;
178                 FILE *in, *out;
179
180                 client = accept(fd, NULL, NULL);
181                 if (client < 0) {
182                         warning_errno("accept failed");
183                         return 1;
184                 }
185                 client2 = dup(client);
186                 if (client2 < 0) {
187                         warning_errno("dup failed");
188                         close(client);
189                         return 1;
190                 }
191
192                 in = xfdopen(client, "r");
193                 out = xfdopen(client2, "w");
194                 serve_one_client(in, out);
195                 fclose(in);
196                 fclose(out);
197         }
198         return 1;
199 }
200
201 static void serve_cache(const char *socket_path, int debug)
202 {
203         int fd;
204
205         fd = unix_stream_listen(socket_path);
206         if (fd < 0)
207                 die_errno("unable to bind to '%s'", socket_path);
208
209         printf("ok\n");
210         fclose(stdout);
211         if (!debug) {
212                 if (!freopen("/dev/null", "w", stderr))
213                         die_errno("unable to point stderr to /dev/null");
214         }
215
216         while (serve_cache_loop(fd))
217                 ; /* nothing */
218
219         close(fd);
220 }
221
222 static const char permissions_advice[] =
223 "The permissions on your socket directory are too loose; other\n"
224 "users may be able to read your cached credentials. Consider running:\n"
225 "\n"
226 "       chmod 0700 %s";
227 static void init_socket_directory(const char *path)
228 {
229         struct stat st;
230         char *path_copy = xstrdup(path);
231         char *dir = dirname(path_copy);
232
233         if (!stat(dir, &st)) {
234                 if (st.st_mode & 077)
235                         die(permissions_advice, dir);
236         } else {
237                 /*
238                  * We must be sure to create the directory with the correct mode,
239                  * not just chmod it after the fact; otherwise, there is a race
240                  * condition in which somebody can chdir to it, sleep, then try to open
241                  * our protected socket.
242                  */
243                 if (safe_create_leading_directories_const(dir) < 0)
244                         die_errno("unable to create directories for '%s'", dir);
245                 if (mkdir(dir, 0700) < 0)
246                         die_errno("unable to mkdir '%s'", dir);
247         }
248
249         if (chdir(dir))
250                 /*
251                  * We don't actually care what our cwd is; we chdir here just to
252                  * be a friendly daemon and avoid tying up our original cwd.
253                  * If this fails, it's OK to just continue without that benefit.
254                  */
255                 ;
256
257         free(path_copy);
258 }
259
260 int cmd_main(int argc, const char **argv)
261 {
262         const char *socket_path;
263         int ignore_sighup = 0;
264         static const char *usage[] = {
265                 "git-credential-cache--daemon [opts] <socket_path>",
266                 NULL
267         };
268         int debug = 0;
269         const struct option options[] = {
270                 OPT_BOOL(0, "debug", &debug,
271                          N_("print debugging messages to stderr")),
272                 OPT_END()
273         };
274
275         git_config_get_bool("credentialcache.ignoresighup", &ignore_sighup);
276
277         argc = parse_options(argc, argv, NULL, options, usage, 0);
278         socket_path = argv[0];
279
280         if (!socket_path)
281                 usage_with_options(usage, options);
282
283         if (!is_absolute_path(socket_path))
284                 die("socket directory must be an absolute path");
285
286         init_socket_directory(socket_path);
287         register_tempfile(&socket_file, socket_path);
288
289         if (ignore_sighup)
290                 signal(SIGHUP, SIG_IGN);
291
292         serve_cache(socket_path, debug);
293         delete_tempfile(&socket_file);
294
295         return 0;
296 }