builtin/credential-cache--daemon.c

   1 #include "builtin.h"
   2 #include "abspath.h"
   3 #include "alloc.h"
   4 #include "gettext.h"
   5 #include "parse-options.h"
   6
   7 #ifndef NO_UNIX_SOCKETS
   8
   9 #include "config.h"
  10 #include "tempfile.h"
  11 #include "credential.h"
  12 #include "unix-socket.h"
  13
  14 struct credential_cache_entry {
  15         struct credential item;
  16         timestamp_t expiration;
  17 };
  18 static struct credential_cache_entry *entries;
  19 static int entries_nr;
  20 static int entries_alloc;
  21
  22 static void cache_credential(struct credential *c, int timeout)
  23 {
  24         struct credential_cache_entry *e;
  25
  26         ALLOC_GROW(entries, entries_nr + 1, entries_alloc);
  27         e = &entries[entries_nr++];
  28
  29         /* take ownership of pointers */
  30         memcpy(&e->item, c, sizeof(*c));
  31         memset(c, 0, sizeof(*c));
  32         e->expiration = time(NULL) + timeout;
  33 }
  34
  35 static struct credential_cache_entry *lookup_credential(const struct credential *c)
  36 {
  37         int i;
  38         for (i = 0; i < entries_nr; i++) {
  39                 struct credential *e = &entries[i].item;
  40                 if (credential_match(c, e))
  41                         return &entries[i];
  42         }
  43         return NULL;
  44 }
  45
  46 static void remove_credential(const struct credential *c)
  47 {
  48         struct credential_cache_entry *e;
  49
  50         e = lookup_credential(c);
  51         if (e)
  52                 e->expiration = 0;
  53 }
  54
  55 static timestamp_t check_expirations(void)
  56 {
  57         static timestamp_t wait_for_entry_until;
  58         int i = 0;
  59         timestamp_t now = time(NULL);
  60         timestamp_t next = TIME_MAX;
  61
  62         /*
  63          * Initially give the client 30 seconds to actually contact us
  64          * and store a credential before we decide there's no point in
  65          * keeping the daemon around.
  66          */
  67         if (!wait_for_entry_until)
  68                 wait_for_entry_until = now + 30;
  69
  70         while (i < entries_nr) {
  71                 if (entries[i].expiration <= now) {
  72                         entries_nr--;
  73                         credential_clear(&entries[i].item);
  74                         if (i != entries_nr)
  75                                 memcpy(&entries[i], &entries[entries_nr], sizeof(*entries));
  76                         /*
  77                          * Stick around 30 seconds in case a new credential
  78                          * shows up (e.g., because we just removed a failed
  79                          * one, and we will soon get the correct one).
  80                          */
  81                         wait_for_entry_until = now + 30;
  82                 }
  83                 else {
  84                         if (entries[i].expiration < next)
  85                                 next = entries[i].expiration;
  86                         i++;
  87                 }
  88         }
  89
  90         if (!entries_nr) {
  91                 if (wait_for_entry_until <= now)
  92                         return 0;
  93                 next = wait_for_entry_until;
  94         }
  95
  96         return next - now;
  97 }
  98
  99 static int read_request(FILE *fh, struct credential *c,
 100                         struct strbuf *action, int *timeout)
 101 {
 102         static struct strbuf item = STRBUF_INIT;
 103         const char *p;
 104
 105         strbuf_getline_lf(&item, fh);
 106         if (!skip_prefix(item.buf, "action=", &p))
 107                 return error("client sent bogus action line: %s", item.buf);
 108         strbuf_addstr(action, p);
 109
 110         strbuf_getline_lf(&item, fh);
 111         if (!skip_prefix(item.buf, "timeout=", &p))
 112                 return error("client sent bogus timeout line: %s", item.buf);
 113         *timeout = atoi(p);
 114
 115         if (credential_read(c, fh) < 0)
 116                 return -1;
 117         return 0;
 118 }
 119
 120 static void serve_one_client(FILE *in, FILE *out)
 121 {
 122         struct credential c = CREDENTIAL_INIT;
 123         struct strbuf action = STRBUF_INIT;
 124         int timeout = -1;
 125
 126         if (read_request(in, &c, &action, &timeout) < 0)
 127                 /* ignore error */ ;
 128         else if (!strcmp(action.buf, "get")) {
 129                 struct credential_cache_entry *e = lookup_credential(&c);
 130                 if (e) {
 131                         fprintf(out, "username=%s\n", e->item.username);
 132                         fprintf(out, "password=%s\n", e->item.password);
 133                         if (e->item.password_expiry_utc != TIME_MAX)
 134                                 fprintf(out, "password_expiry_utc=%"PRItime"\n",
 135                                         e->item.password_expiry_utc);
 136                 }
 137         }
 138         else if (!strcmp(action.buf, "exit")) {
 139                 /*
 140                  * It's important that we clean up our socket first, and then
 141                  * signal the client only once we have finished the cleanup.
 142                  * Calling exit() directly does this, because we clean up in
 143                  * our atexit() handler, and then signal the client when our
 144                  * process actually ends, which closes the socket and gives
 145                  * them EOF.
 146                  */
 147                 exit(0);
 148         }
 149         else if (!strcmp(action.buf, "erase"))
 150                 remove_credential(&c);
 151         else if (!strcmp(action.buf, "store")) {
 152                 if (timeout < 0)
 153                         warning("cache client didn't specify a timeout");
 154                 else if (!c.username || !c.password)
 155                         warning("cache client gave us a partial credential");
 156                 else {
 157                         remove_credential(&c);
 158                         cache_credential(&c, timeout);
 159                 }
 160         }
 161         else
 162                 warning("cache client sent unknown action: %s", action.buf);
 163
 164         credential_clear(&c);
 165         strbuf_release(&action);
 166 }
 167
 168 static int serve_cache_loop(int fd)
 169 {
 170         struct pollfd pfd;
 171         timestamp_t wakeup;
 172
 173         wakeup = check_expirations();
 174         if (!wakeup)
 175                 return 0;
 176
 177         pfd.fd = fd;
 178         pfd.events = POLLIN;
 179         if (poll(&pfd, 1, 1000 * wakeup) < 0) {
 180                 if (errno != EINTR)
 181                         die_errno("poll failed");
 182                 return 1;
 183         }
 184
 185         if (pfd.revents & POLLIN) {
 186                 int client, client2;
 187                 FILE *in, *out;
 188
 189                 client = accept(fd, NULL, NULL);
 190                 if (client < 0) {
 191                         warning_errno("accept failed");
 192                         return 1;
 193                 }
 194                 client2 = dup(client);
 195                 if (client2 < 0) {
 196                         warning_errno("dup failed");
 197                         close(client);
 198                         return 1;
 199                 }
 200
 201                 in = xfdopen(client, "r");
 202                 out = xfdopen(client2, "w");
 203                 serve_one_client(in, out);
 204                 fclose(in);
 205                 fclose(out);
 206         }
 207         return 1;
 208 }
 209
 210 static void serve_cache(const char *socket_path, int debug)
 211 {
 212         struct unix_stream_listen_opts opts = UNIX_STREAM_LISTEN_OPTS_INIT;
 213         int fd;
 214
 215         fd = unix_stream_listen(socket_path, &opts);
 216         if (fd < 0)
 217                 die_errno("unable to bind to '%s'", socket_path);
 218
 219         printf("ok\n");
 220         fclose(stdout);
 221         if (!debug) {
 222                 if (!freopen("/dev/null", "w", stderr))
 223                         die_errno("unable to point stderr to /dev/null");
 224         }
 225
 226         while (serve_cache_loop(fd))
 227                 ; /* nothing */
 228
 229         close(fd);
 230 }
 231
 232 static const char permissions_advice[] = N_(
 233 "The permissions on your socket directory are too loose; other\n"
 234 "users may be able to read your cached credentials. Consider running:\n"
 235 "\n"
 236 "       chmod 0700 %s");
 237 static void init_socket_directory(const char *path)
 238 {
 239         struct stat st;
 240         char *path_copy = xstrdup(path);
 241         char *dir = dirname(path_copy);
 242
 243         if (!stat(dir, &st)) {
 244                 if (st.st_mode & 077)
 245                         die(_(permissions_advice), dir);
 246         } else {
 247                 /*
 248                  * We must be sure to create the directory with the correct mode,
 249                  * not just chmod it after the fact; otherwise, there is a race
 250                  * condition in which somebody can chdir to it, sleep, then try to open
 251                  * our protected socket.
 252                  */
 253                 if (safe_create_leading_directories_const(dir) < 0)
 254                         die_errno("unable to create directories for '%s'", dir);
 255                 if (mkdir(dir, 0700) < 0)
 256                         die_errno("unable to mkdir '%s'", dir);
 257         }
 258
 259         if (chdir(dir))
 260                 /*
 261                  * We don't actually care what our cwd is; we chdir here just to
 262                  * be a friendly daemon and avoid tying up our original cwd.
 263                  * If this fails, it's OK to just continue without that benefit.
 264                  */
 265                 ;
 266
 267         free(path_copy);
 268 }
 269
 270 int cmd_credential_cache_daemon(int argc, const char **argv, const char *prefix)
 271 {
 272         struct tempfile *socket_file;
 273         const char *socket_path;
 274         int ignore_sighup = 0;
 275         static const char *usage[] = {
 276                 "git credential-cache--daemon [--debug] <socket-path>",
 277                 NULL
 278         };
 279         int debug = 0;
 280         const struct option options[] = {
 281                 OPT_BOOL(0, "debug", &debug,
 282                          N_("print debugging messages to stderr")),
 283                 OPT_END()
 284         };
 285
 286         git_config_get_bool("credentialcache.ignoresighup", &ignore_sighup);
 287
 288         argc = parse_options(argc, argv, prefix, options, usage, 0);
 289         socket_path = argv[0];
 290
 291         if (!socket_path)
 292                 usage_with_options(usage, options);
 293
 294         if (!is_absolute_path(socket_path))
 295                 die("socket directory must be an absolute path");
 296
 297         init_socket_directory(socket_path);
 298         socket_file = register_tempfile(socket_path);
 299
 300         if (ignore_sighup)
 301                 signal(SIGHUP, SIG_IGN);
 302
 303         serve_cache(socket_path, debug);
 304         delete_tempfile(&socket_file);
 305
 306         return 0;
 307 }
 308
 309 #else
 310
 311 int cmd_credential_cache_daemon(int argc, const char **argv, const char *prefix)
 312 {
 313         const char * const usage[] = {
 314                 "git credential-cache--daemon [--debug] <socket-path>",
 315                 "",
 316                 "credential-cache--daemon is disabled in this build of Git",
 317                 NULL
 318         };
 319         struct option options[] = { OPT_END() };
 320
 321         argc = parse_options(argc, argv, prefix, options, usage, 0);
 322         die(_("credential-cache--daemon unavailable; no unix socket support"));
 323 }
 324
 325 #endif /* NO_UNIX_SOCKET */