builtin/credential-cache--daemon.c

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