credential-cache--daemon.c

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