builtin/credential-cache--daemon.c

   1 #include "builtin.h"
   2 #include "abspath.h"
   3 #include "alloc.h"
   4 #include "gettext.h"
   5 #include "object-file.h"
   6 #include "parse-options.h"
   7
   8 #ifndef NO_UNIX_SOCKETS
   9
  10 #include "config.h"
  11 #include "tempfile.h"
  12 #include "credential.h"
  13 #include "unix-socket.h"
  14
  15 struct credential_cache_entry {
  16         struct credential item;
  17         timestamp_t expiration;
  18 };
  19 static struct credential_cache_entry *entries;
  20 static int entries_nr;
  21 static int entries_alloc;
  22
  23 static void cache_credential(struct credential *c, int timeout)
  24 {
  25         struct credential_cache_entry *e;
  26
  27         ALLOC_GROW(entries, entries_nr + 1, entries_alloc);
  28         e = &entries[entries_nr++];
  29
  30         /* take ownership of pointers */
  31         memcpy(&e->item, c, sizeof(*c));
  32         memset(c, 0, sizeof(*c));
  33         e->expiration = time(NULL) + timeout;
  34 }
  35
  36 static struct credential_cache_entry *lookup_credential(const struct credential *c)
  37 {
  38         int i;
  39         for (i = 0; i < entries_nr; i++) {
  40                 struct credential *e = &entries[i].item;
  41                 if (credential_match(c, e))
  42                         return &entries[i];
  43         }
  44         return NULL;
  45 }
  46
  47 static void remove_credential(const struct credential *c)
  48 {
  49         struct credential_cache_entry *e;
  50
  51         e = lookup_credential(c);
  52         if (e)
  53                 e->expiration = 0;
  54 }
  55
  56 static timestamp_t check_expirations(void)
  57 {
  58         static timestamp_t wait_for_entry_until;
  59         int i = 0;
  60         timestamp_t now = time(NULL);
  61         timestamp_t next = TIME_MAX;
  62
  63         /*
  64          * Initially give the client 30 seconds to actually contact us
  65          * and store a credential before we decide there's no point in
  66          * keeping the daemon around.
  67          */
  68         if (!wait_for_entry_until)
  69                 wait_for_entry_until = now + 30;
  70
  71         while (i < entries_nr) {
  72                 if (entries[i].expiration <= now) {
  73                         entries_nr--;
  74                         credential_clear(&entries[i].item);
  75                         if (i != entries_nr)
  76                                 memcpy(&entries[i], &entries[entries_nr], sizeof(*entries));
  77                         /*
  78                          * Stick around 30 seconds in case a new credential
  79                          * shows up (e.g., because we just removed a failed
  80                          * one, and we will soon get the correct one).
  81                          */
  82                         wait_for_entry_until = now + 30;
  83                 }
  84                 else {
  85                         if (entries[i].expiration < next)
  86                                 next = entries[i].expiration;
  87                         i++;
  88                 }
  89         }
  90
  91         if (!entries_nr) {
  92                 if (wait_for_entry_until <= now)
  93                         return 0;
  94                 next = wait_for_entry_until;
  95         }
  96
  97         return next - now;
  98 }
  99
 100 static int read_request(FILE *fh, struct credential *c,
 101                         struct strbuf *action, int *timeout)
 102 {
 103         static struct strbuf item = STRBUF_INIT;
 104         const char *p;
 105
 106         strbuf_getline_lf(&item, fh);
 107         if (!skip_prefix(item.buf, "action=", &p))
 108                 return error("client sent bogus action line: %s", item.buf);
 109         strbuf_addstr(action, p);
 110
 111         strbuf_getline_lf(&item, fh);
 112         if (!skip_prefix(item.buf, "timeout=", &p))
 113                 return error("client sent bogus timeout line: %s", item.buf);
 114         *timeout = atoi(p);
 115
 116         if (credential_read(c, fh) < 0)
 117                 return -1;
 118         return 0;
 119 }
 120
 121 static void serve_one_client(FILE *in, FILE *out)
 122 {
 123         struct credential c = CREDENTIAL_INIT;
 124         struct strbuf action = STRBUF_INIT;
 125         int timeout = -1;
 126
 127         if (read_request(in, &c, &action, &timeout) < 0)
 128                 /* ignore error */ ;
 129         else if (!strcmp(action.buf, "get")) {
 130                 struct credential_cache_entry *e = lookup_credential(&c);
 131                 if (e) {
 132                         fprintf(out, "username=%s\n", e->item.username);
 133                         fprintf(out, "password=%s\n", e->item.password);
 134                         if (e->item.password_expiry_utc != TIME_MAX)
 135                                 fprintf(out, "password_expiry_utc=%"PRItime"\n",
 136                                         e->item.password_expiry_utc);
 137                         if (e->item.oauth_refresh_token)
 138                                 fprintf(out, "oauth_refresh_token=%s\n",
 139                                         e->item.oauth_refresh_token);
 140                 }
 141         }
 142         else if (!strcmp(action.buf, "exit")) {
 143                 /*
 144                  * It's important that we clean up our socket first, and then
 145                  * signal the client only once we have finished the cleanup.
 146                  * Calling exit() directly does this, because we clean up in
 147                  * our atexit() handler, and then signal the client when our
 148                  * process actually ends, which closes the socket and gives
 149                  * them EOF.
 150                  */
 151                 exit(0);
 152         }
 153         else if (!strcmp(action.buf, "erase"))
 154                 remove_credential(&c);
 155         else if (!strcmp(action.buf, "store")) {
 156                 if (timeout < 0)
 157                         warning("cache client didn't specify a timeout");
 158                 else if (!c.username || !c.password)
 159                         warning("cache client gave us a partial credential");
 160                 else {
 161                         remove_credential(&c);
 162                         cache_credential(&c, timeout);
 163                 }
 164         }
 165         else
 166                 warning("cache client sent unknown action: %s", action.buf);
 167
 168         credential_clear(&c);
 169         strbuf_release(&action);
 170 }
 171
 172 static int serve_cache_loop(int fd)
 173 {
 174         struct pollfd pfd;
 175         timestamp_t wakeup;
 176
 177         wakeup = check_expirations();
 178         if (!wakeup)
 179                 return 0;
 180
 181         pfd.fd = fd;
 182         pfd.events = POLLIN;
 183         if (poll(&pfd, 1, 1000 * wakeup) < 0) {
 184                 if (errno != EINTR)
 185                         die_errno("poll failed");
 186                 return 1;
 187         }
 188
 189         if (pfd.revents & POLLIN) {
 190                 int client, client2;
 191                 FILE *in, *out;
 192
 193                 client = accept(fd, NULL, NULL);
 194                 if (client < 0) {
 195                         warning_errno("accept failed");
 196                         return 1;
 197                 }
 198                 client2 = dup(client);
 199                 if (client2 < 0) {
 200                         warning_errno("dup failed");
 201                         close(client);
 202                         return 1;
 203                 }
 204
 205                 in = xfdopen(client, "r");
 206                 out = xfdopen(client2, "w");
 207                 serve_one_client(in, out);
 208                 fclose(in);
 209                 fclose(out);
 210         }
 211         return 1;
 212 }
 213
 214 static void serve_cache(const char *socket_path, int debug)
 215 {
 216         struct unix_stream_listen_opts opts = UNIX_STREAM_LISTEN_OPTS_INIT;
 217         int fd;
 218
 219         fd = unix_stream_listen(socket_path, &opts);
 220         if (fd < 0)
 221                 die_errno("unable to bind to '%s'", socket_path);
 222
 223         printf("ok\n");
 224         fclose(stdout);
 225         if (!debug) {
 226                 if (!freopen("/dev/null", "w", stderr))
 227                         die_errno("unable to point stderr to /dev/null");
 228         }
 229
 230         while (serve_cache_loop(fd))
 231                 ; /* nothing */
 232
 233         close(fd);
 234 }
 235
 236 static const char permissions_advice[] = N_(
 237 "The permissions on your socket directory are too loose; other\n"
 238 "users may be able to read your cached credentials. Consider running:\n"
 239 "\n"
 240 "       chmod 0700 %s");
 241 static void init_socket_directory(const char *path)
 242 {
 243         struct stat st;
 244         char *path_copy = xstrdup(path);
 245         char *dir = dirname(path_copy);
 246
 247         if (!stat(dir, &st)) {
 248                 if (st.st_mode & 077)
 249                         die(_(permissions_advice), dir);
 250         } else {
 251                 /*
 252                  * We must be sure to create the directory with the correct mode,
 253                  * not just chmod it after the fact; otherwise, there is a race
 254                  * condition in which somebody can chdir to it, sleep, then try to open
 255                  * our protected socket.
 256                  */
 257                 if (safe_create_leading_directories_const(dir) < 0)
 258                         die_errno("unable to create directories for '%s'", dir);
 259                 if (mkdir(dir, 0700) < 0)
 260                         die_errno("unable to mkdir '%s'", dir);
 261         }
 262
 263         if (chdir(dir))
 264                 /*
 265                  * We don't actually care what our cwd is; we chdir here just to
 266                  * be a friendly daemon and avoid tying up our original cwd.
 267                  * If this fails, it's OK to just continue without that benefit.
 268                  */
 269                 ;
 270
 271         free(path_copy);
 272 }
 273
 274 int cmd_credential_cache_daemon(int argc, const char **argv, const char *prefix)
 275 {
 276         struct tempfile *socket_file;
 277         const char *socket_path;
 278         int ignore_sighup = 0;
 279         static const char *usage[] = {
 280                 "git credential-cache--daemon [--debug] <socket-path>",
 281                 NULL
 282         };
 283         int debug = 0;
 284         const struct option options[] = {
 285                 OPT_BOOL(0, "debug", &debug,
 286                          N_("print debugging messages to stderr")),
 287                 OPT_END()
 288         };
 289
 290         git_config_get_bool("credentialcache.ignoresighup", &ignore_sighup);
 291
 292         argc = parse_options(argc, argv, prefix, options, usage, 0);
 293         socket_path = argv[0];
 294
 295         if (!socket_path)
 296                 usage_with_options(usage, options);
 297
 298         if (!is_absolute_path(socket_path))
 299                 die("socket directory must be an absolute path");
 300
 301         init_socket_directory(socket_path);
 302         socket_file = register_tempfile(socket_path);
 303
 304         if (ignore_sighup)
 305                 signal(SIGHUP, SIG_IGN);
 306
 307         serve_cache(socket_path, debug);
 308         delete_tempfile(&socket_file);
 309
 310         return 0;
 311 }
 312
 313 #else
 314
 315 int cmd_credential_cache_daemon(int argc, const char **argv, const char *prefix)
 316 {
 317         const char * const usage[] = {
 318                 "git credential-cache--daemon [--debug] <socket-path>",
 319                 "",
 320                 "credential-cache--daemon is disabled in this build of Git",
 321                 NULL
 322         };
 323         struct option options[] = { OPT_END() };
 324
 325         argc = parse_options(argc, argv, prefix, options, usage, 0);
 326         die(_("credential-cache--daemon unavailable; no unix socket support"));
 327 }
 328
 329 #endif /* NO_UNIX_SOCKET */