credential-cache--daemon.con commit Merge branch 'sb/t4005-modernize' into maint (dbcf775)
   1#include "cache.h"
   2#include "tempfile.h"
   3#include "credential.h"
   4#include "unix-socket.h"
   5#include "parse-options.h"
   6
   7static struct tempfile socket_file;
   8
   9struct credential_cache_entry {
  10        struct credential item;
  11        unsigned long expiration;
  12};
  13static struct credential_cache_entry *entries;
  14static int entries_nr;
  15static int entries_alloc;
  16
  17static void cache_credential(struct credential *c, int timeout)
  18{
  19        struct credential_cache_entry *e;
  20
  21        ALLOC_GROW(entries, entries_nr + 1, entries_alloc);
  22        e = &entries[entries_nr++];
  23
  24        /* take ownership of pointers */
  25        memcpy(&e->item, c, sizeof(*c));
  26        memset(c, 0, sizeof(*c));
  27        e->expiration = time(NULL) + timeout;
  28}
  29
  30static struct credential_cache_entry *lookup_credential(const struct credential *c)
  31{
  32        int i;
  33        for (i = 0; i < entries_nr; i++) {
  34                struct credential *e = &entries[i].item;
  35                if (credential_match(c, e))
  36                        return &entries[i];
  37        }
  38        return NULL;
  39}
  40
  41static void remove_credential(const struct credential *c)
  42{
  43        struct credential_cache_entry *e;
  44
  45        e = lookup_credential(c);
  46        if (e)
  47                e->expiration = 0;
  48}
  49
  50static int check_expirations(void)
  51{
  52        static unsigned long wait_for_entry_until;
  53        int i = 0;
  54        unsigned long now = time(NULL);
  55        unsigned long next = (unsigned long)-1;
  56
  57        /*
  58         * Initially give the client 30 seconds to actually contact us
  59         * and store a credential before we decide there's no point in
  60         * keeping the daemon around.
  61         */
  62        if (!wait_for_entry_until)
  63                wait_for_entry_until = now + 30;
  64
  65        while (i < entries_nr) {
  66                if (entries[i].expiration <= now) {
  67                        entries_nr--;
  68                        credential_clear(&entries[i].item);
  69                        if (i != entries_nr)
  70                                memcpy(&entries[i], &entries[entries_nr], sizeof(*entries));
  71                        /*
  72                         * Stick around 30 seconds in case a new credential
  73                         * shows up (e.g., because we just removed a failed
  74                         * one, and we will soon get the correct one).
  75                         */
  76                        wait_for_entry_until = now + 30;
  77                }
  78                else {
  79                        if (entries[i].expiration < next)
  80                                next = entries[i].expiration;
  81                        i++;
  82                }
  83        }
  84
  85        if (!entries_nr) {
  86                if (wait_for_entry_until <= now)
  87                        return 0;
  88                next = wait_for_entry_until;
  89        }
  90
  91        return next - now;
  92}
  93
  94static int read_request(FILE *fh, struct credential *c,
  95                        struct strbuf *action, int *timeout) {
  96        static struct strbuf item = STRBUF_INIT;
  97        const char *p;
  98
  99        strbuf_getline_lf(&item, fh);
 100        if (!skip_prefix(item.buf, "action=", &p))
 101                return error("client sent bogus action line: %s", item.buf);
 102        strbuf_addstr(action, p);
 103
 104        strbuf_getline_lf(&item, fh);
 105        if (!skip_prefix(item.buf, "timeout=", &p))
 106                return error("client sent bogus timeout line: %s", item.buf);
 107        *timeout = atoi(p);
 108
 109        if (credential_read(c, fh) < 0)
 110                return -1;
 111        return 0;
 112}
 113
 114static void serve_one_client(FILE *in, FILE *out)
 115{
 116        struct credential c = CREDENTIAL_INIT;
 117        struct strbuf action = STRBUF_INIT;
 118        int timeout = -1;
 119
 120        if (read_request(in, &c, &action, &timeout) < 0)
 121                /* ignore error */ ;
 122        else if (!strcmp(action.buf, "get")) {
 123                struct credential_cache_entry *e = lookup_credential(&c);
 124                if (e) {
 125                        fprintf(out, "username=%s\n", e->item.username);
 126                        fprintf(out, "password=%s\n", e->item.password);
 127                }
 128        }
 129        else if (!strcmp(action.buf, "exit")) {
 130                /*
 131                 * It's important that we clean up our socket first, and then
 132                 * signal the client only once we have finished the cleanup.
 133                 * Calling exit() directly does this, because we clean up in
 134                 * our atexit() handler, and then signal the client when our
 135                 * process actually ends, which closes the socket and gives
 136                 * them EOF.
 137                 */
 138                exit(0);
 139        }
 140        else if (!strcmp(action.buf, "erase"))
 141                remove_credential(&c);
 142        else if (!strcmp(action.buf, "store")) {
 143                if (timeout < 0)
 144                        warning("cache client didn't specify a timeout");
 145                else if (!c.username || !c.password)
 146                        warning("cache client gave us a partial credential");
 147                else {
 148                        remove_credential(&c);
 149                        cache_credential(&c, timeout);
 150                }
 151        }
 152        else
 153                warning("cache client sent unknown action: %s", action.buf);
 154
 155        credential_clear(&c);
 156        strbuf_release(&action);
 157}
 158
 159static int serve_cache_loop(int fd)
 160{
 161        struct pollfd pfd;
 162        unsigned long wakeup;
 163
 164        wakeup = check_expirations();
 165        if (!wakeup)
 166                return 0;
 167
 168        pfd.fd = fd;
 169        pfd.events = POLLIN;
 170        if (poll(&pfd, 1, 1000 * wakeup) < 0) {
 171                if (errno != EINTR)
 172                        die_errno("poll failed");
 173                return 1;
 174        }
 175
 176        if (pfd.revents & POLLIN) {
 177                int client, client2;
 178                FILE *in, *out;
 179
 180                client = accept(fd, NULL, NULL);
 181                if (client < 0) {
 182                        warning_errno("accept failed");
 183                        return 1;
 184                }
 185                client2 = dup(client);
 186                if (client2 < 0) {
 187                        warning_errno("dup failed");
 188                        close(client);
 189                        return 1;
 190                }
 191
 192                in = xfdopen(client, "r");
 193                out = xfdopen(client2, "w");
 194                serve_one_client(in, out);
 195                fclose(in);
 196                fclose(out);
 197        }
 198        return 1;
 199}
 200
 201static void serve_cache(const char *socket_path, int debug)
 202{
 203        int fd;
 204
 205        fd = unix_stream_listen(socket_path);
 206        if (fd < 0)
 207                die_errno("unable to bind to '%s'", socket_path);
 208
 209        printf("ok\n");
 210        fclose(stdout);
 211        if (!debug) {
 212                if (!freopen("/dev/null", "w", stderr))
 213                        die_errno("unable to point stderr to /dev/null");
 214        }
 215
 216        while (serve_cache_loop(fd))
 217                ; /* nothing */
 218
 219        close(fd);
 220}
 221
 222static const char permissions_advice[] = N_(
 223"The permissions on your socket directory are too loose; other\n"
 224"users may be able to read your cached credentials. Consider running:\n"
 225"\n"
 226"       chmod 0700 %s");
 227static void init_socket_directory(const char *path)
 228{
 229        struct stat st;
 230        char *path_copy = xstrdup(path);
 231        char *dir = dirname(path_copy);
 232
 233        if (!stat(dir, &st)) {
 234                if (st.st_mode & 077)
 235                        die(_(permissions_advice), dir);
 236        } else {
 237                /*
 238                 * We must be sure to create the directory with the correct mode,
 239                 * not just chmod it after the fact; otherwise, there is a race
 240                 * condition in which somebody can chdir to it, sleep, then try to open
 241                 * our protected socket.
 242                 */
 243                if (safe_create_leading_directories_const(dir) < 0)
 244                        die_errno("unable to create directories for '%s'", dir);
 245                if (mkdir(dir, 0700) < 0)
 246                        die_errno("unable to mkdir '%s'", dir);
 247        }
 248
 249        if (chdir(dir))
 250                /*
 251                 * We don't actually care what our cwd is; we chdir here just to
 252                 * be a friendly daemon and avoid tying up our original cwd.
 253                 * If this fails, it's OK to just continue without that benefit.
 254                 */
 255                ;
 256
 257        free(path_copy);
 258}
 259
 260int cmd_main(int argc, const char **argv)
 261{
 262        const char *socket_path;
 263        int ignore_sighup = 0;
 264        static const char *usage[] = {
 265                "git-credential-cache--daemon [opts] <socket_path>",
 266                NULL
 267        };
 268        int debug = 0;
 269        const struct option options[] = {
 270                OPT_BOOL(0, "debug", &debug,
 271                         N_("print debugging messages to stderr")),
 272                OPT_END()
 273        };
 274
 275        git_config_get_bool("credentialcache.ignoresighup", &ignore_sighup);
 276
 277        argc = parse_options(argc, argv, NULL, options, usage, 0);
 278        socket_path = argv[0];
 279
 280        if (!socket_path)
 281                usage_with_options(usage, options);
 282
 283        if (!is_absolute_path(socket_path))
 284                die("socket directory must be an absolute path");
 285
 286        init_socket_directory(socket_path);
 287        register_tempfile(&socket_file, socket_path);
 288
 289        if (ignore_sighup)
 290                signal(SIGHUP, SIG_IGN);
 291
 292        serve_cache(socket_path, debug);
 293        delete_tempfile(&socket_file);
 294
 295        return 0;
 296}