From 986b2514cc68368181ad8b5e2000346fc8394c9a Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Alvin=20=C5=A0ipraga?= Date: Wed, 7 Dec 2022 16:43:06 +0100 Subject: network: wifi: check SSID when AP interfaces go up When an AP goes up, the kernel may emit a netlink event indicating that the interface has gained carrier. In that event, we should check if the SSID has changed before attempting to reconfigure. Not doing so means that the link->ssid member is not updated, leading to a potential mismatch if some of the .network configurations match on SSID=. There are however scenarios where the above heuristic is not enough. Specifically, if the interface carrier state flip-flops within a short enough interval, the internal throttling of netlink events inside the kernel may suppress intermediate linkdown+linkup events (cf. Linux net/core/link_watch.c). So there is no linkup event to react on. To improve on the latter scenario, it is proposed to make newer kernels emit an NL80211_CMD_START_AP multicast event when an AP goes up. This event will not be dropped by link_watch. systemd-networkd can then react to such events as well, and optionally reconfigure the link if the SSID has changed. This will only work with newer kernels though. --- src/network/networkd-link.c | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'src/network/networkd-link.c') diff --git a/src/network/networkd-link.c b/src/network/networkd-link.c index c46b8f5b2e..95a7d75e53 100644 --- a/src/network/networkd-link.c +++ b/src/network/networkd-link.c @@ -58,6 +58,7 @@ #include "networkd-sriov.h" #include "networkd-state-file.h" #include "networkd-sysctl.h" +#include "networkd-wifi.h" #include "set.h" #include "socket-util.h" #include "stdio-util.h" @@ -1498,6 +1499,15 @@ static int link_carrier_gained(Link *link) { force_reconfigure = link->previous_ssid && !streq_ptr(link->previous_ssid, link->ssid); link->previous_ssid = mfree(link->previous_ssid); + /* AP and P2P-GO interfaces may have a new SSID - update the link properties in case a new .network + * profile wants to match on it with SSID= in its [Match] section. + */ + if (IN_SET(link->wlan_iftype, NL80211_IFTYPE_AP, NL80211_IFTYPE_P2P_GO)) { + r = link_get_wlan_interface(link); + if (r < 0) + return r; + } + /* At this stage, both wlan and link information should be up-to-date. Hence, it is not necessary to * call RTM_GETLINK, NL80211_CMD_GET_INTERFACE, or NL80211_CMD_GET_STATION commands, and simply call * link_reconfigure_impl(). Note, link_reconfigure_impl() returns 1 when the link is reconfigured. */ -- cgit v1.2.1