LTTng

Since commit:

commit 590f0324d6dfd382f79229a7934fa8b5b661641f
Author: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Date:   Fri Aug 30 18:10:56 2019 -0400

    Fix: validate that session, host and basepath are legal

    Ensure that session name, hostname and the session's base path
    do not contain dots ('.') to safeguard against malformed names
    that could be used to walk-up the relay daemon output path
    hierarchy.

    Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

────────────────────────────────────────────────────────────────────────────────────────────────────────
modified: src/bin/lttng-relayd/session.c
────────────────────────────────────────────────────────────────────────────────────────────────────────
@ session.c:101 @ struct relay_session *session_create(const char *session_name,
        uint32_t minor)
{
    int ret;
    struct relay_session *session;
    struct relay_session *session = NULL;

    if (session_name && strstr(session_name, ".")) {
        ERR("Illegal character in session name: \"%s\"",
                session_name);
        goto error;
    }
    if (base_path && strstr(base_path, "../")) {
        ERR("Invalid session base path walks up the path hierarchy: \"%s\"",
                base_path);
        goto error;
    }
    if (hostname && strstr(hostname, ".")) {
        ERR("Invalid character in hostname: \"%s\"",
                hostname);
        goto error;
    }

    session = zmalloc(sizeof(*session));
    if (!session) {

lttng-relayd does not accept dots in the hostname.

We have a host for which gethostname return the FQDN (e.g ci-node-el8-amd64-03-01.internal.efficios.com). This is legal. We can either allow dot in hostname or go fetch the "localname" (hostname --short). A basic implementation of the last solution is available here as a WIP here: https://review.lttng.org/c/lttng-tools/+/2740

The "downside" with getting the shortname is that we would need to do the same for the lttng-ust metadata env generator in lttng-ust. Do we really want to restrict hostname with dots? I imagine that this is to prevent stuff ala hostname = ../../../myhostname?

Opinion?