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