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policy: detect if the hostname was changed outside NetworkManager

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When updating the hostname we can now detect if someone else changed
the hostname: if so, search for hostname candidates in the dhcp
configuration but avoid to fallback to the hostname saved when NM
started or querying dns for a reverse lookup of the current IP.
This commit is contained in:
Francesco Giudici 2017-02-17 16:22:30 +01:00
parent b7557fa723
commit d34add6f00
1 changed files with 74 additions and 15 deletions
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89
src/nm-policy.c
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@ -87,6 +87,8 @@ typedef struct {
char *orig_hostname; /* hostname at NM start time */
char *cur_hostname; /* hostname we want to assign */
char *last_hostname; /* last hostname NM set (to detect if someone else changed it in the meanwhile) */
gboolean changing_hostname; /* hostname set operation still in progress */
GArray *ip6_prefix_delegations; /* pool of ip6 prefixes delegated to all devices */
} NMPolicyPrivate;
@ -412,6 +414,8 @@ settings_set_hostname_cb (const char *hostname,
gboolean result,
gpointer user_data)
{
NMPolicy *self = NM_POLICY (user_data);
NMPolicyPrivate *priv = NM_POLICY_GET_PRIVATE (self);
int ret = 0;
if (!result) {
@ -426,8 +430,10 @@ settings_set_hostname_cb (const char *hostname,
}
}
priv->changing_hostname = FALSE;
if (!ret)
nm_dispatcher_call_hostname (NULL, NULL, NULL);
g_object_unref (self);
}
#define HOST_NAME_BUFSIZE (HOST_NAME_MAX + 2)
@ -440,6 +446,15 @@ _get_hostname (NMPolicy *self, char **hostname)
g_assert (hostname && *hostname == NULL);
/* If there is an in-progress hostname change, return
* the last hostname set as would be set soon...
*/
if (priv->changing_hostname) {
_LOGT (LOGD_DNS, "gethostname: \"%s\" (last on set)", priv->last_hostname);
*hostname = g_strdup (priv->last_hostname);
return *hostname;
}
/* try to get the hostname via dbus... */
if (nm_settings_get_transient_hostname (priv->settings, hostname)) {
_LOGT (LOGD_DNS, "gethostname: \"%s\" (from dbus)", *hostname);
@ -521,6 +536,11 @@ _set_hostname (NMPolicy *self,
return;
}
/* Keep track of the last set hostname */
g_free (priv->last_hostname);
priv->last_hostname = g_strdup (name);
priv->changing_hostname = TRUE;
_LOGI (LOGD_DNS, "sethostname: '%s' (%s)", name, msg);
/* Ask NMSettings to update the transient hostname using its
@ -528,7 +548,7 @@ _set_hostname (NMPolicy *self,
nm_settings_set_transient_hostname (priv->settings,
name,
settings_set_hostname_cb,
NULL);
g_object_ref (self));
}
static void
@ -563,19 +583,43 @@ update_system_hostname (NMPolicy *self, NMDevice *best4, NMDevice *best6)
{
NMPolicyPrivate *priv = NM_POLICY_GET_PRIVATE (self);
char *configured_hostname = NULL;
gs_free char *temp_hostname = NULL;
const char *dhcp_hostname, *p;
NMIP4Config *ip4_config;
NMIP6Config *ip6_config;
gboolean external_hostname = FALSE;
g_return_if_fail (self != NULL);
nm_clear_g_cancellable (&priv->lookup_cancellable);
/* Check if the hostname was set externally to NM, so that in that case
* we can avoid to fallback to the one we got when we started.
* Consider "not specific" hostnames as equal. */
if ( _get_hostname (self, &temp_hostname)
&& !nm_streq0 (temp_hostname, priv->last_hostname)
&& ( nm_utils_is_specific_hostname (temp_hostname)
|| nm_utils_is_specific_hostname (priv->last_hostname))) {
external_hostname = TRUE;
_LOGI (LOGD_DNS, "current hostname was changed outside NetworkManager: '%s'",
temp_hostname);
if (!nm_streq0 (temp_hostname, priv->orig_hostname)) {
/* Update original (fallback) hostname */
g_free (priv->orig_hostname);
if (nm_utils_is_specific_hostname (temp_hostname)) {
priv->orig_hostname = temp_hostname;
temp_hostname = NULL;
} else
priv->orig_hostname = NULL;
}
}
/* Hostname precedence order:
*
* 1) a configured hostname (from settings)
* 2) automatic hostname from the default device's config (DHCP, VPN, etc)
* 3) the original hostname when NM started
* 3) the last hostname set outside NM
* 4) reverse-DNS of the best device's IPv4 address
*
*/
@ -595,14 +639,6 @@ update_system_hostname (NMPolicy *self, NMDevice *best4, NMDevice *best6)
if (!best6)
best6 = get_best_ip6_device (self, TRUE);
if (!best4 && !best6) {
/* No best device; fall back to original hostname or if there wasn't
* one, 'localhost.localdomain'
*/
_set_hostname (self, priv->orig_hostname, "no default device");
return;
}
if (best4) {
NMDhcp4Config *dhcp4_config;
@ -643,8 +679,20 @@ update_system_hostname (NMPolicy *self, NMDevice *best4, NMDevice *best6)
}
}
/* If no automatically-configured hostname, try using the hostname from
* when NM started up.
/* If an hostname was set outside NetworkManager keep it */
if (external_hostname)
return;
if (!best4 && !best6) {
/* No best device; fall back to the last hostname set externally
* to NM or if there wasn't one, 'localhost.localdomain'
*/
_set_hostname (self, priv->orig_hostname, "no default device");
return;
}
/* If no automatically-configured hostname, try using the last hostname
* set externally to NM
*/
if (priv->orig_hostname) {
_set_hostname (self, priv->orig_hostname, "from system startup");
@ -2004,6 +2052,15 @@ dns_config_changed (NMDnsManager *dns_manager, gpointer user_data)
/* Re-start the hostname lookup thread if we don't have hostname yet. */
if (priv->lookup_addr) {
char *str = NULL;
gs_free char *hostname = NULL;
/* Check if the hostname was externally set */
if ( _get_hostname (self, &hostname)
&& nm_utils_is_specific_hostname (hostname)
&& !nm_streq0 (hostname, priv->last_hostname)) {
g_clear_object (&priv->lookup_addr);
return;
}
_LOGD (LOGD_DNS, "restarting reverse-lookup thread for address %s",
(str = g_inet_address_to_string (priv->lookup_addr)));
@ -2213,11 +2270,12 @@ constructed (GObject *object)
/* Grab hostname on startup and use that if nothing provides one */
if (_get_hostname (self, &hostname)) {
/* init last_hostname */
priv->last_hostname = hostname;
/* only cache it if it's a valid hostname */
if (nm_utils_is_specific_hostname (hostname))
priv->orig_hostname = hostname;
else
g_free (hostname);
priv->orig_hostname = g_strdup (hostname);
}
priv->firewall_manager = g_object_ref (nm_firewall_manager_get ());
@ -2310,6 +2368,7 @@ dispose (GObject *object)
g_clear_pointer (&priv->orig_hostname, g_free);
g_clear_pointer (&priv->cur_hostname, g_free);
g_clear_pointer (&priv->last_hostname, g_free);
if (priv->settings) {
g_signal_handlers_disconnect_by_data (priv->settings, priv);