builtin/credential-cache--daemon.c

   1 #include "builtin.h"
   2 #include "abspath.h"
   3 #include "gettext.h"
   4 #include "object-file.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, 0))
  41                         return &entries[i];
  42         }
  43         return NULL;
  44 }
  45
  46 static void remove_credential(const struct credential *c, int match_password)
  47 {
  48         struct credential_cache_entry *e;
  49
  50         int i;
  51         for (i = 0; i < entries_nr; i++) {
  52                 e = &entries[i];
  53                 if (credential_match(c, &e->item, match_password))
  54                         e->expiration = 0;
  55         }
  56 }
  57
  58 static timestamp_t check_expirations(void)
  59 {
  60         static timestamp_t wait_for_entry_until;
  61         int i = 0;
  62         timestamp_t now = time(NULL);
  63         timestamp_t next = TIME_MAX;
  64
  65         /*
  66          * Initially give the client 30 seconds to actually contact us
  67          * and store a credential before we decide there's no point in
  68          * keeping the daemon around.
  69          */
  70         if (!wait_for_entry_until)
  71                 wait_for_entry_until = now + 30;
  72
  73         while (i < entries_nr) {
  74                 if (entries[i].expiration <= now) {
  75                         entries_nr--;
  76                         credential_clear(&entries[i].item);
  77                         if (i != entries_nr)
  78                                 memcpy(&entries[i], &entries[entries_nr], sizeof(*entries));
  79                         /*
  80                          * Stick around 30 seconds in case a new credential
  81                          * shows up (e.g., because we just removed a failed
  82                          * one, and we will soon get the correct one).
  83                          */
  84                         wait_for_entry_until = now + 30;
  85                 }
  86                 else {
  87                         if (entries[i].expiration < next)
  88                                 next = entries[i].expiration;
  89                         i++;
  90                 }
  91         }
  92
  93         if (!entries_nr) {
  94                 if (wait_for_entry_until <= now)
  95                         return 0;
  96                 next = wait_for_entry_until;
  97         }
  98
  99         return next - now;
 100 }
 101
 102 static int read_request(FILE *fh, struct credential *c,
 103                         struct strbuf *action, int *timeout)
 104 {
 105         static struct strbuf item = STRBUF_INIT;
 106         const char *p;
 107
 108         strbuf_getline_lf(&item, fh);
 109         if (!skip_prefix(item.buf, "action=", &p))
 110                 return error("client sent bogus action line: %s", item.buf);
 111         strbuf_addstr(action, p);
 112
 113         strbuf_getline_lf(&item, fh);
 114         if (!skip_prefix(item.buf, "timeout=", &p))
 115                 return error("client sent bogus timeout line: %s", item.buf);
 116         *timeout = atoi(p);
 117
 118         if (credential_read(c, fh) < 0)
 119                 return -1;
 120         return 0;
 121 }
 122
 123 static void serve_one_client(FILE *in, FILE *out)
 124 {
 125         struct credential c = CREDENTIAL_INIT;
 126         struct strbuf action = STRBUF_INIT;
 127         int timeout = -1;
 128
 129         if (read_request(in, &c, &action, &timeout) < 0)
 130                 /* ignore error */ ;
 131         else if (!strcmp(action.buf, "get")) {
 132                 struct credential_cache_entry *e = lookup_credential(&c);
 133                 if (e) {
 134                         fprintf(out, "username=%s\n", e->item.username);
 135                         fprintf(out, "password=%s\n", e->item.password);
 136                         if (e->item.password_expiry_utc != TIME_MAX)
 137                                 fprintf(out, "password_expiry_utc=%"PRItime"\n",
 138                                         e->item.password_expiry_utc);
 139                         if (e->item.oauth_refresh_token)
 140                                 fprintf(out, "oauth_refresh_token=%s\n",
 141                                         e->item.oauth_refresh_token);
 142                 }
 143         }
 144         else if (!strcmp(action.buf, "exit")) {
 145                 /*
 146                  * It's important that we clean up our socket first, and then
 147                  * signal the client only once we have finished the cleanup.
 148                  * Calling exit() directly does this, because we clean up in
 149                  * our atexit() handler, and then signal the client when our
 150                  * process actually ends, which closes the socket and gives
 151                  * them EOF.
 152                  */
 153                 exit(0);
 154         }
 155         else if (!strcmp(action.buf, "erase"))
 156                 remove_credential(&c, 1);
 157         else if (!strcmp(action.buf, "store")) {
 158                 if (timeout < 0)
 159                         warning("cache client didn't specify a timeout");
 160                 else if (!c.username || !c.password)
 161                         warning("cache client gave us a partial credential");
 162                 else {
 163                         remove_credential(&c, 0);
 164                         cache_credential(&c, timeout);
 165                 }
 166         }
 167         else
 168                 warning("cache client sent unknown action: %s", action.buf);
 169
 170         credential_clear(&c);
 171         strbuf_release(&action);
 172 }
 173
 174 static int serve_cache_loop(int fd)
 175 {
 176         struct pollfd pfd;
 177         timestamp_t wakeup;
 178
 179         wakeup = check_expirations();
 180         if (!wakeup)
 181                 return 0;
 182
 183         pfd.fd = fd;
 184         pfd.events = POLLIN;
 185         if (poll(&pfd, 1, 1000 * wakeup) < 0) {
 186                 if (errno != EINTR)
 187                         die_errno("poll failed");
 188                 return 1;
 189         }
 190
 191         if (pfd.revents & POLLIN) {
 192                 int client, client2;
 193                 FILE *in, *out;
 194
 195                 client = accept(fd, NULL, NULL);
 196                 if (client < 0) {
 197                         warning_errno("accept failed");
 198                         return 1;
 199                 }
 200                 client2 = dup(client);
 201                 if (client2 < 0) {
 202                         warning_errno("dup failed");
 203                         close(client);
 204                         return 1;
 205                 }
 206
 207                 in = xfdopen(client, "r");
 208                 out = xfdopen(client2, "w");
 209                 serve_one_client(in, out);
 210                 fclose(in);
 211                 fclose(out);
 212         }
 213         return 1;
 214 }
 215
 216 static void serve_cache(const char *socket_path, int debug)
 217 {
 218         struct unix_stream_listen_opts opts = UNIX_STREAM_LISTEN_OPTS_INIT;
 219         int fd;
 220
 221         fd = unix_stream_listen(socket_path, &opts);
 222         if (fd < 0)
 223                 die_errno("unable to bind to '%s'", socket_path);
 224
 225         printf("ok\n");
 226         fclose(stdout);
 227         if (!debug) {
 228                 if (!freopen("/dev/null", "w", stderr))
 229                         die_errno("unable to point stderr to /dev/null");
 230         }
 231
 232         while (serve_cache_loop(fd))
 233                 ; /* nothing */
 234
 235         close(fd);
 236 }
 237
 238 static const char permissions_advice[] = N_(
 239 "The permissions on your socket directory are too loose; other\n"
 240 "users may be able to read your cached credentials. Consider running:\n"
 241 "\n"
 242 "       chmod 0700 %s");
 243 static void init_socket_directory(const char *path)
 244 {
 245         struct stat st;
 246         char *path_copy = xstrdup(path);
 247         char *dir = dirname(path_copy);
 248
 249         if (!stat(dir, &st)) {
 250                 if (st.st_mode & 077)
 251                         die(_(permissions_advice), dir);
 252         } else {
 253                 /*
 254                  * We must be sure to create the directory with the correct mode,
 255                  * not just chmod it after the fact; otherwise, there is a race
 256                  * condition in which somebody can chdir to it, sleep, then try to open
 257                  * our protected socket.
 258                  */
 259                 if (safe_create_leading_directories_const(dir) < 0)
 260                         die_errno("unable to create directories for '%s'", dir);
 261                 if (mkdir(dir, 0700) < 0)
 262                         die_errno("unable to mkdir '%s'", dir);
 263         }
 264
 265         if (chdir(dir))
 266                 /*
 267                  * We don't actually care what our cwd is; we chdir here just to
 268                  * be a friendly daemon and avoid tying up our original cwd.
 269                  * If this fails, it's OK to just continue without that benefit.
 270                  */
 271                 ;
 272
 273         free(path_copy);
 274 }
 275
 276 int cmd_credential_cache_daemon(int argc, const char **argv, const char *prefix)
 277 {
 278         struct tempfile *socket_file;
 279         const char *socket_path;
 280         int ignore_sighup = 0;
 281         static const char *usage[] = {
 282                 "git credential-cache--daemon [--debug] <socket-path>",
 283                 NULL
 284         };
 285         int debug = 0;
 286         const struct option options[] = {
 287                 OPT_BOOL(0, "debug", &debug,
 288                          N_("print debugging messages to stderr")),
 289                 OPT_END()
 290         };
 291
 292         git_config_get_bool("credentialcache.ignoresighup", &ignore_sighup);
 293
 294         argc = parse_options(argc, argv, prefix, options, usage, 0);
 295         socket_path = argv[0];
 296
 297         if (!have_unix_sockets())
 298                 die(_("credential-cache--daemon unavailable; no unix socket support"));
 299         if (!socket_path)
 300                 usage_with_options(usage, options);
 301
 302         if (!is_absolute_path(socket_path))
 303                 die("socket directory must be an absolute path");
 304
 305         init_socket_directory(socket_path);
 306         socket_file = register_tempfile(socket_path);
 307
 308         if (ignore_sighup)
 309                 signal(SIGHUP, SIG_IGN);
 310
 311         serve_cache(socket_path, debug);
 312         delete_tempfile(&socket_file);
 313
 314         return 0;
 315 }
 316
 317 #else
 318
 319 int cmd_credential_cache_daemon(int argc, const char **argv, const char *prefix)
 320 {
 321         const char * const usage[] = {
 322                 "git credential-cache--daemon [--debug] <socket-path>",
 323                 "",
 324                 "credential-cache--daemon is disabled in this build of Git",
 325                 NULL
 326         };
 327         struct option options[] = { OPT_END() };
 328
 329         argc = parse_options(argc, argv, prefix, options, usage, 0);
 330         die(_("credential-cache--daemon unavailable; no unix socket support"));
 331 }
 332
 333 #endif /* NO_UNIX_SOCKET */