SymbX/systemd
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Merge pull request #30837 from poettering/varlink-over-ssh

Browse Source 
varlink: add "ssh:" transport for talking to remote servers
This commit is contained in:
Yu Watanabe
2024-01-09 10:14:03 +09:00
committed by GitHub
parent fc1f05ebab bcb1bb379e
commit 35716eed55
13 changed files with 204 additions and 35 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/shared/varlink.c
+101 -16
View File
@@ -450,6 +450,10 @@ int varlink_connect_exec(Varlink **ret, const char *_command, char **_argv) {
if (socketpair(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0, pair) < 0)
return log_debug_errno(errno, "Failed to allocate AF_UNIX socket pair: %m");
r = fd_nonblock(pair[1], false);
if (r < 0)
return log_debug_errno(r, "Failed to disable O_NONBLOCK for varlink socket: %m");
r = safe_fork_full(
"(sd-vlexec)",
/* stdio_fds= */ NULL,
@@ -507,39 +511,120 @@ int varlink_connect_exec(Varlink **ret, const char *_command, char **_argv) {
return 0;
}
static int varlink_connect_ssh(Varlink **ret, const char *where) {
_cleanup_close_pair_ int pair[2] = EBADF_PAIR;
_cleanup_(sigkill_waitp) pid_t pid = 0;
int r;
assert_return(ret, -EINVAL);
assert_return(where, -EINVAL);
/* Connects to an SSH server via OpenSSH 9.4's -W switch to connect to a remote AF_UNIX socket. For
* now we do not expose this function directly, but only via varlink_connect_url(). */
const char *ssh = secure_getenv("SYSTEMD_SSH") ?: "ssh";
if (!path_is_valid(ssh))
return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), "SSH path is not valid, refusing: %s", ssh);
const char *e = strchr(where, ':');
if (!e)
return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), "SSH specification lacks a : separator between host and path, refusing: %s", where);
_cleanup_free_ char *h = strndup(where, e - where);
if (!h)
return log_oom_debug();
_cleanup_free_ char *c = strdup(e + 1);
if (!c)
return log_oom_debug();
if (!path_is_absolute(c))
return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), "Remote AF_UNIX socket path is not absolute, refusing: %s", c);
_cleanup_free_ char *p = NULL;
r = path_simplify_alloc(c, &p);
if (r < 0)
return r;
if (!path_is_normalized(p))
return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), "Specified path is not normalized, refusing: %s", p);
log_debug("Forking off SSH child process '%s -W %s %s'.", ssh, p, h);
if (socketpair(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0, pair) < 0)
return log_debug_errno(errno, "Failed to allocate AF_UNIX socket pair: %m");
r = safe_fork_full(
"(sd-vlssh)",
/* stdio_fds= */ (int[]) { pair[1], pair[1], STDERR_FILENO },
/* except_fds= */ NULL,
/* n_except_fds= */ 0,
FORK_RESET_SIGNALS|FORK_CLOSE_ALL_FDS|FORK_DEATHSIG_SIGTERM|FORK_REOPEN_LOG|FORK_LOG|FORK_RLIMIT_NOFILE_SAFE|FORK_REARRANGE_STDIO,
&pid);
if (r < 0)
return log_debug_errno(r, "Failed to spawn process: %m");
if (r == 0) {
/* Child */
execlp(ssh, "ssh", "-W", p, h, NULL);
log_debug_errno(errno, "Failed to invoke %s: %m", ssh);
_exit(EXIT_FAILURE);
}
pair[1] = safe_close(pair[1]);
Varlink *v;
r = varlink_new(&v);
if (r < 0)
return log_debug_errno(r, "Failed to create varlink object: %m");
v->fd = TAKE_FD(pair[0]);
v->af = AF_UNIX;
v->exec_pid = TAKE_PID(pid);
varlink_set_state(v, VARLINK_IDLE_CLIENT);
*ret = v;
return 0;
}
int varlink_connect_url(Varlink **ret, const char *url) {
_cleanup_free_ char *c = NULL;
const char *p;
bool exec;
enum {
SCHEME_UNIX,
SCHEME_EXEC,
SCHEME_SSH,
} scheme;
int r;
assert_return(ret, -EINVAL);
assert_return(url, -EINVAL);
// FIXME: Add support for vsock:, ssh-exec:, ssh-unix: URL schemes here. (The latter with OpenSSH
// 9.4's -W switch for referencing remote AF_UNIX sockets.)
// FIXME: Maybe add support for vsock: and ssh-exec: URL schemes here.
/* The Varlink URL scheme is a bit underdefined. We support only the unix: transport for now, plus an
* exec: transport we made up ourselves. Strictly speaking this shouldn't even be called URL, since
* it has nothing to do with Internet URLs by RFC. */
/* The Varlink URL scheme is a bit underdefined. We support only the spec-defined unix: transport for
* now, plus exec:, ssh: transports we made up ourselves. Strictly speaking this shouldn't even be
* called "URL", since it has nothing to do with Internet URLs by RFC. */
p = startswith(url, "unix:");
if (p)
exec = false;
else {
p = startswith(url, "exec:");
if (!p)
return log_debug_errno(SYNTHETIC_ERRNO(EPROTONOSUPPORT), "URL scheme not supported.");
exec = true;
}
scheme = SCHEME_UNIX;
else if ((p = startswith(url, "exec:")))
scheme = SCHEME_EXEC;
else if ((p = startswith(url, "ssh:")))
scheme = SCHEME_SSH;
else
return log_debug_errno(SYNTHETIC_ERRNO(EPROTONOSUPPORT), "URL scheme not supported.");
/* The varlink.org reference C library supports more than just file system paths. We might want to
* support that one day too. For now simply refuse that. */
if (p[strcspn(p, ";?#")] != '\0')
return log_debug_errno(SYNTHETIC_ERRNO(EPROTONOSUPPORT), "URL parameterization with ';', '?', '#' not supported.");
if (exec || p[0] != '@') { /* no validity checks for abstract namespace */
if (scheme == SCHEME_SSH)
return varlink_connect_ssh(ret, p);
if (scheme == SCHEME_EXEC || p[0] != '@') { /* no path validity checks for abstract namespace sockets */
if (!path_is_absolute(p))
return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), "Specified path not absolute, refusing.");
@@ -552,7 +637,7 @@ int varlink_connect_url(Varlink **ret, const char *url) {
return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), "Specified path is not normalized, refusing.");
}
if (exec)
if (scheme == SCHEME_EXEC)
return varlink_connect_exec(ret, c, NULL);
return varlink_connect_address(ret, c ?: p);