credential-cache--daemon.con commit Merge branch 'jk/path-name-safety-2.5' into jk/path-name-safety-2.6 (717e355)
   1#include "cache.h"
   2#include "tempfile.h"
   3#include "credential.h"
   4#include "unix-socket.h"
   5#include "sigchain.h"
   6#include "parse-options.h"
   7
   8static struct tempfile socket_file;
   9
  10struct credential_cache_entry {
  11        struct credential item;
  12        unsigned long expiration;
  13};
  14static struct credential_cache_entry *entries;
  15static int entries_nr;
  16static int entries_alloc;
  17
  18static 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
  31static 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
  42static 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
  51static int check_expirations(void)
  52{
  53        static unsigned long wait_for_entry_until;
  54        int i = 0;
  55        unsigned long now = time(NULL);
  56        unsigned long next = (unsigned long)-1;
  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
  95static 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(&item, fh, '\n');
 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(&item, fh, '\n');
 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
 115static 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                exit(0);
 132        else if (!strcmp(action.buf, "erase"))
 133                remove_credential(&c);
 134        else if (!strcmp(action.buf, "store")) {
 135                if (timeout < 0)
 136                        warning("cache client didn't specify a timeout");
 137                else if (!c.username || !c.password)
 138                        warning("cache client gave us a partial credential");
 139                else {
 140                        remove_credential(&c);
 141                        cache_credential(&c, timeout);
 142                }
 143        }
 144        else
 145                warning("cache client sent unknown action: %s", action.buf);
 146
 147        credential_clear(&c);
 148        strbuf_release(&action);
 149}
 150
 151static int serve_cache_loop(int fd)
 152{
 153        struct pollfd pfd;
 154        unsigned long wakeup;
 155
 156        wakeup = check_expirations();
 157        if (!wakeup)
 158                return 0;
 159
 160        pfd.fd = fd;
 161        pfd.events = POLLIN;
 162        if (poll(&pfd, 1, 1000 * wakeup) < 0) {
 163                if (errno != EINTR)
 164                        die_errno("poll failed");
 165                return 1;
 166        }
 167
 168        if (pfd.revents & POLLIN) {
 169                int client, client2;
 170                FILE *in, *out;
 171
 172                client = accept(fd, NULL, NULL);
 173                if (client < 0) {
 174                        warning("accept failed: %s", strerror(errno));
 175                        return 1;
 176                }
 177                client2 = dup(client);
 178                if (client2 < 0) {
 179                        warning("dup failed: %s", strerror(errno));
 180                        close(client);
 181                        return 1;
 182                }
 183
 184                in = xfdopen(client, "r");
 185                out = xfdopen(client2, "w");
 186                serve_one_client(in, out);
 187                fclose(in);
 188                fclose(out);
 189        }
 190        return 1;
 191}
 192
 193static void serve_cache(const char *socket_path, int debug)
 194{
 195        int fd;
 196
 197        fd = unix_stream_listen(socket_path);
 198        if (fd < 0)
 199                die_errno("unable to bind to '%s'", socket_path);
 200
 201        printf("ok\n");
 202        fclose(stdout);
 203        if (!debug) {
 204                if (!freopen("/dev/null", "w", stderr))
 205                        die_errno("unable to point stderr to /dev/null");
 206        }
 207
 208        while (serve_cache_loop(fd))
 209                ; /* nothing */
 210
 211        close(fd);
 212}
 213
 214static const char permissions_advice[] =
 215"The permissions on your socket directory are too loose; other\n"
 216"users may be able to read your cached credentials. Consider running:\n"
 217"\n"
 218"       chmod 0700 %s";
 219static void check_socket_directory(const char *path)
 220{
 221        struct stat st;
 222        char *path_copy = xstrdup(path);
 223        char *dir = dirname(path_copy);
 224
 225        if (!stat(dir, &st)) {
 226                if (st.st_mode & 077)
 227                        die(permissions_advice, dir);
 228                free(path_copy);
 229                return;
 230        }
 231
 232        /*
 233         * We must be sure to create the directory with the correct mode,
 234         * not just chmod it after the fact; otherwise, there is a race
 235         * condition in which somebody can chdir to it, sleep, then try to open
 236         * our protected socket.
 237         */
 238        if (safe_create_leading_directories_const(dir) < 0)
 239                die_errno("unable to create directories for '%s'", dir);
 240        if (mkdir(dir, 0700) < 0)
 241                die_errno("unable to mkdir '%s'", dir);
 242        free(path_copy);
 243}
 244
 245int main(int argc, const char **argv)
 246{
 247        const char *socket_path;
 248        static const char *usage[] = {
 249                "git-credential-cache--daemon [opts] <socket_path>",
 250                NULL
 251        };
 252        int debug = 0;
 253        const struct option options[] = {
 254                OPT_BOOL(0, "debug", &debug,
 255                         N_("print debugging messages to stderr")),
 256                OPT_END()
 257        };
 258
 259        argc = parse_options(argc, argv, NULL, options, usage, 0);
 260        socket_path = argv[0];
 261
 262        if (!socket_path)
 263                usage_with_options(usage, options);
 264
 265        check_socket_directory(socket_path);
 266        register_tempfile(&socket_file, socket_path);
 267        serve_cache(socket_path, debug);
 268        delete_tempfile(&socket_file);
 269
 270        return 0;
 271}