git/builtin/credential-cache--daemon.c
Jeff Hostetler 55144ccb0a unix-socket: add backlog size option to unix_stream_listen()
Update `unix_stream_listen()` to take an options structure to override
default behaviors.  This commit includes the size of the `listen()` backlog.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-03-15 14:32:51 -07:00

320 lines
7.5 KiB
C

#include "builtin.h"
#include "parse-options.h"
#ifndef NO_UNIX_SOCKETS
#include "config.h"
#include "tempfile.h"
#include "credential.h"
#include "unix-socket.h"
struct credential_cache_entry {
struct credential item;
timestamp_t expiration;
};
static struct credential_cache_entry *entries;
static int entries_nr;
static int entries_alloc;
static void cache_credential(struct credential *c, int timeout)
{
struct credential_cache_entry *e;
ALLOC_GROW(entries, entries_nr + 1, entries_alloc);
e = &entries[entries_nr++];
/* take ownership of pointers */
memcpy(&e->item, c, sizeof(*c));
memset(c, 0, sizeof(*c));
e->expiration = time(NULL) + timeout;
}
static struct credential_cache_entry *lookup_credential(const struct credential *c)
{
int i;
for (i = 0; i < entries_nr; i++) {
struct credential *e = &entries[i].item;
if (credential_match(c, e))
return &entries[i];
}
return NULL;
}
static void remove_credential(const struct credential *c)
{
struct credential_cache_entry *e;
e = lookup_credential(c);
if (e)
e->expiration = 0;
}
static timestamp_t check_expirations(void)
{
static timestamp_t wait_for_entry_until;
int i = 0;
timestamp_t now = time(NULL);
timestamp_t next = TIME_MAX;
/*
* Initially give the client 30 seconds to actually contact us
* and store a credential before we decide there's no point in
* keeping the daemon around.
*/
if (!wait_for_entry_until)
wait_for_entry_until = now + 30;
while (i < entries_nr) {
if (entries[i].expiration <= now) {
entries_nr--;
credential_clear(&entries[i].item);
if (i != entries_nr)
memcpy(&entries[i], &entries[entries_nr], sizeof(*entries));
/*
* Stick around 30 seconds in case a new credential
* shows up (e.g., because we just removed a failed
* one, and we will soon get the correct one).
*/
wait_for_entry_until = now + 30;
}
else {
if (entries[i].expiration < next)
next = entries[i].expiration;
i++;
}
}
if (!entries_nr) {
if (wait_for_entry_until <= now)
return 0;
next = wait_for_entry_until;
}
return next - now;
}
static int read_request(FILE *fh, struct credential *c,
struct strbuf *action, int *timeout)
{
static struct strbuf item = STRBUF_INIT;
const char *p;
strbuf_getline_lf(&item, fh);
if (!skip_prefix(item.buf, "action=", &p))
return error("client sent bogus action line: %s", item.buf);
strbuf_addstr(action, p);
strbuf_getline_lf(&item, fh);
if (!skip_prefix(item.buf, "timeout=", &p))
return error("client sent bogus timeout line: %s", item.buf);
*timeout = atoi(p);
if (credential_read(c, fh) < 0)
return -1;
return 0;
}
static void serve_one_client(FILE *in, FILE *out)
{
struct credential c = CREDENTIAL_INIT;
struct strbuf action = STRBUF_INIT;
int timeout = -1;
if (read_request(in, &c, &action, &timeout) < 0)
/* ignore error */ ;
else if (!strcmp(action.buf, "get")) {
struct credential_cache_entry *e = lookup_credential(&c);
if (e) {
fprintf(out, "username=%s\n", e->item.username);
fprintf(out, "password=%s\n", e->item.password);
}
}
else if (!strcmp(action.buf, "exit")) {
/*
* It's important that we clean up our socket first, and then
* signal the client only once we have finished the cleanup.
* Calling exit() directly does this, because we clean up in
* our atexit() handler, and then signal the client when our
* process actually ends, which closes the socket and gives
* them EOF.
*/
exit(0);
}
else if (!strcmp(action.buf, "erase"))
remove_credential(&c);
else if (!strcmp(action.buf, "store")) {
if (timeout < 0)
warning("cache client didn't specify a timeout");
else if (!c.username || !c.password)
warning("cache client gave us a partial credential");
else {
remove_credential(&c);
cache_credential(&c, timeout);
}
}
else
warning("cache client sent unknown action: %s", action.buf);
credential_clear(&c);
strbuf_release(&action);
}
static int serve_cache_loop(int fd)
{
struct pollfd pfd;
timestamp_t wakeup;
wakeup = check_expirations();
if (!wakeup)
return 0;
pfd.fd = fd;
pfd.events = POLLIN;
if (poll(&pfd, 1, 1000 * wakeup) < 0) {
if (errno != EINTR)
die_errno("poll failed");
return 1;
}
if (pfd.revents & POLLIN) {
int client, client2;
FILE *in, *out;
client = accept(fd, NULL, NULL);
if (client < 0) {
warning_errno("accept failed");
return 1;
}
client2 = dup(client);
if (client2 < 0) {
warning_errno("dup failed");
close(client);
return 1;
}
in = xfdopen(client, "r");
out = xfdopen(client2, "w");
serve_one_client(in, out);
fclose(in);
fclose(out);
}
return 1;
}
static void serve_cache(const char *socket_path, int debug)
{
struct unix_stream_listen_opts opts = UNIX_STREAM_LISTEN_OPTS_INIT;
int fd;
fd = unix_stream_listen(socket_path, &opts);
if (fd < 0)
die_errno("unable to bind to '%s'", socket_path);
printf("ok\n");
fclose(stdout);
if (!debug) {
if (!freopen("/dev/null", "w", stderr))
die_errno("unable to point stderr to /dev/null");
}
while (serve_cache_loop(fd))
; /* nothing */
close(fd);
}
static const char permissions_advice[] = N_(
"The permissions on your socket directory are too loose; other\n"
"users may be able to read your cached credentials. Consider running:\n"
"\n"
" chmod 0700 %s");
static void init_socket_directory(const char *path)
{
struct stat st;
char *path_copy = xstrdup(path);
char *dir = dirname(path_copy);
if (!stat(dir, &st)) {
if (st.st_mode & 077)
die(_(permissions_advice), dir);
} else {
/*
* We must be sure to create the directory with the correct mode,
* not just chmod it after the fact; otherwise, there is a race
* condition in which somebody can chdir to it, sleep, then try to open
* our protected socket.
*/
if (safe_create_leading_directories_const(dir) < 0)
die_errno("unable to create directories for '%s'", dir);
if (mkdir(dir, 0700) < 0)
die_errno("unable to mkdir '%s'", dir);
}
if (chdir(dir))
/*
* We don't actually care what our cwd is; we chdir here just to
* be a friendly daemon and avoid tying up our original cwd.
* If this fails, it's OK to just continue without that benefit.
*/
;
free(path_copy);
}
int cmd_credential_cache_daemon(int argc, const char **argv, const char *prefix)
{
struct tempfile *socket_file;
const char *socket_path;
int ignore_sighup = 0;
static const char *usage[] = {
"git-credential-cache--daemon [opts] <socket_path>",
NULL
};
int debug = 0;
const struct option options[] = {
OPT_BOOL(0, "debug", &debug,
N_("print debugging messages to stderr")),
OPT_END()
};
git_config_get_bool("credentialcache.ignoresighup", &ignore_sighup);
argc = parse_options(argc, argv, prefix, options, usage, 0);
socket_path = argv[0];
if (!socket_path)
usage_with_options(usage, options);
if (!is_absolute_path(socket_path))
die("socket directory must be an absolute path");
init_socket_directory(socket_path);
socket_file = register_tempfile(socket_path);
if (ignore_sighup)
signal(SIGHUP, SIG_IGN);
serve_cache(socket_path, debug);
delete_tempfile(&socket_file);
return 0;
}
#else
int cmd_credential_cache_daemon(int argc, const char **argv, const char *prefix)
{
const char * const usage[] = {
"git credential-cache--daemon [options] <action>",
"",
"credential-cache--daemon is disabled in this build of Git",
NULL
};
struct option options[] = { OPT_END() };
argc = parse_options(argc, argv, prefix, options, usage, 0);
die(_("credential-cache--daemon unavailable; no unix socket support"));
}
#endif /* NO_UNIX_SOCKET */