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ip: shared: stop using the global forwarding

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As we introduced the ipv4.forwarding property in a8a2e6d727 ('ip-config:
Support configuring per-device IPv4 sysctl forwarding option'), we must
not enable or disable the global forwarding setting in the kernel, as it
affects to all the devices, maybe forcing them to behave in a way
different to what the user requested in ipv4.forwarding.

Instead, we need to selectively enable or disable the per-device forwarding
settings. Specifically, only devices activated with ipv4.forwarding=auto
must have their forwarding enabled or disabled depending on shared
connections. Devices with yes/no must not be affected by shared connections.

Also, devices with ipv4.forwarding=auto must get the proper forwarding value
on activation, but also change it when shared connections appear or
disappear dynamically. Use the new sharing-ipv4-change signal from
nm_manager to achieve it.

Fixes: a8a2e6d727 ('ip-config: Support configuring per-device IPv4 sysctl forwarding option')
(cherry picked from commit 32cbf4c629)
This commit is contained in:
Íñigo Huguet 2025-05-02 10:02:23 +02:00 • committed by Íñigo Huguet
parent d8e3561eaf
commit 2a264ee841
1 changed files with 93 additions and 33 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

126
src/core/devices/nm-device.c
View file

@ -692,6 +692,8 @@ typedef struct _NMDevicePrivate {
IPDevStateData ipdev_data_unspec;
gulong sharing_ipv4_changed_id;
struct {
/* If we set the addrgenmode6, this records the previously set value. */
guint8 previous_mode_val;
@ -866,6 +868,8 @@ static void _dev_ipshared4_spawn_dnsmasq(NMDevice *self);
static void _dev_ipshared6_start(NMDevice *self);
static void _dev_ipforwarding4_start(NMDevice *self, int addr_family);
static void
_cleanup_ip_pre(NMDevice *self, int addr_family, CleanupType cleanup_type, gboolean preserve_dhcp);
@ -13163,17 +13167,12 @@ activate_stage3_ip_config_for_addr_family(NMDevice *self, int addr_family)
goto out_devip;
if (IS_IPv4) {
NMSettingIPConfigForwarding ipv4_forwarding = _prop_get_ipv4_forwarding(self);
if (NM_IN_SET(ipv4_forwarding,
NM_SETTING_IP_CONFIG_FORWARDING_NO,
NM_SETTING_IP_CONFIG_FORWARDING_YES)) {
nm_device_sysctl_ip_conf_set(self, AF_INET, "forwarding", ipv4_forwarding ? "1" : "0");
}
priv->ipll_data_4.v4.mode = _prop_get_ipv4_link_local(self);
if (priv->ipll_data_4.v4.mode == NM_SETTING_IP4_LL_ENABLED)
_dev_ipll4_start(self);
_dev_ipforwarding4_start(self, addr_family);
if (nm_streq(priv->ipv4_method, NM_SETTING_IP4_CONFIG_METHOD_AUTO))
_dev_ipdhcpx_start(self, AF_INET);
else if (nm_streq(priv->ipv4_method, NM_SETTING_IP4_CONFIG_METHOD_LINK_LOCAL)) {
@ -13608,19 +13607,6 @@ _dev_ipshared4_init(NMDevice *self)
break;
}
if (nm_platform_sysctl_get_int32(nm_device_get_platform(self),
NMP_SYSCTL_PATHID_ABSOLUTE("/proc/sys/net/ipv4/ip_forward"),
-1)
== 1) {
/* nothing to do. */
} else if (!nm_platform_sysctl_set(nm_device_get_platform(self),
NMP_SYSCTL_PATHID_ABSOLUTE("/proc/sys/net/ipv4/ip_forward"),
"1")) {
errsv = errno;
_LOGW_ipshared(AF_INET, "error enabling IPv4 forwarding: %s", nm_strerror_native(errsv));
return FALSE;
}
if (nm_platform_sysctl_get_int32(nm_device_get_platform(self),
NMP_SYSCTL_PATHID_ABSOLUTE("/proc/sys/net/ipv4/ip_dynaddr"),
-1)
@ -13815,28 +13801,102 @@ _dev_ipshared6_start(NMDevice *self)
/*****************************************************************************/
/**
* Set the device's forwarding to the specified value. If %NM_TERNARY_DEFAULT is specified,
* it's set to the kernel's default, otherwise it's set to the specific value.
*/
static void
_dev_ipforwarding_cleanup(NMDevice *self, int addr_family, CleanupType cleanup_type)
_dev_ipforwarding4_set(NMDevice *self, NMTernary val)
{
gs_free const char *default_forwarding = NULL;
gs_free const char *current_forwarding = NULL;
const char *val_str;
if (val != NM_TERNARY_DEFAULT) {
val_str = val ? "1" : "0";
} else {
default_forwarding = nm_platform_sysctl_get(
nm_device_get_platform(self),
NMP_SYSCTL_PATHID_ABSOLUTE("/proc/sys/net/ipv4/conf/default/forwarding"));
if (!default_forwarding) {
_LOGW(LOGD_DEVICE,
"error setting IPv4 forwarding: can't read default forwarding value: %s",
nm_strerror_native(errno));
return; /* Non fatal */
}
val_str = default_forwarding;
}
current_forwarding = nm_device_sysctl_ip_conf_get(self, AF_INET, "forwarding");
if (nm_streq0(current_forwarding, val_str))
return;
if (!nm_device_sysctl_ip_conf_set(self, AF_INET, "forwarding", val_str))
_LOGW(LOGD_DEVICE,
"error setting IPv4 forwarding to '%s': %s",
val_str,
nm_strerror_native(errno));
}
static void
_dev_ipforwarding4_auto_cb(NMManager *manager, gboolean sharing_ipv4, gpointer data)
{
NMDevice *self = NM_DEVICE(data);
_dev_ipforwarding4_set(self, sharing_ipv4 ? NM_TERNARY_TRUE : NM_TERNARY_DEFAULT);
}
static void
_dev_ipforwarding4_start(NMDevice *self, int addr_family)
{
NMDevicePrivate *priv = NM_DEVICE_GET_PRIVATE(self);
NMSettingIPConfigForwarding ipv4_forwarding = _prop_get_ipv4_forwarding(self);
NMTernary new_forwarding = NM_TERNARY_DEFAULT;
/* IPv6 per-interface forwarding not supported yet */
if (addr_family != AF_INET)
return;
if (nm_streq(priv->ipv4_method, NM_SETTING_IP4_CONFIG_METHOD_SHARED)) {
new_forwarding = NM_TERNARY_TRUE;
} else if (ipv4_forwarding == NM_SETTING_IP_CONFIG_FORWARDING_YES) {
new_forwarding = NM_TERNARY_TRUE;
} else if (ipv4_forwarding == NM_SETTING_IP_CONFIG_FORWARDING_NO) {
new_forwarding = NM_TERNARY_FALSE;
} else if (ipv4_forwarding == NM_SETTING_IP_CONFIG_FORWARDING_AUTO) {
if (nm_manager_get_sharing_ipv4(NM_MANAGER_GET))
new_forwarding = NM_TERNARY_TRUE;
else
new_forwarding = NM_TERNARY_DEFAULT;
if (!priv->sharing_ipv4_changed_id)
priv->sharing_ipv4_changed_id = g_signal_connect(NM_MANAGER_GET,
NM_MANAGER_SHARING_IPV4_CHANGED,
G_CALLBACK(_dev_ipforwarding4_auto_cb),
self);
} else {
nm_assert_not_reached();
}
_dev_ipforwarding4_set(self, new_forwarding);
}
static void
_dev_ipforwarding_cleanup(NMDevice *self, int addr_family, CleanupType cleanup_type)
{
NMDevicePrivate *priv = NM_DEVICE_GET_PRIVATE(self);
if (!NM_IS_IPv4(addr_family))
return;
if (!NM_IN_SET(cleanup_type, CLEANUP_TYPE_DECONFIGURE, CLEANUP_TYPE_KEEP_REAPPLY))
return;
nm_clear_g_signal_handler(NM_MANAGER_GET, &priv->sharing_ipv4_changed_id);
default_forwarding = nm_platform_sysctl_get(
nm_device_get_platform(self),
NMP_SYSCTL_PATHID_ABSOLUTE("/proc/sys/net/ipv4/conf/default/forwarding"));
if (!default_forwarding)
return; /* Non fatal */
current_forwarding = nm_device_sysctl_ip_conf_get(self, AF_INET, "forwarding");
if (!nm_streq0(current_forwarding, default_forwarding))
nm_device_sysctl_ip_conf_set(self, AF_INET, "forwarding", default_forwarding);
if (NM_IN_SET(cleanup_type, CLEANUP_TYPE_DECONFIGURE, CLEANUP_TYPE_KEEP_REAPPLY)) {
/* Deconfigure by restoring kernel's default */
_dev_ipforwarding4_set(self, NM_TERNARY_DEFAULT);
}
}
/*****************************************************************************/