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nl80211: Fix race condition in detecting MAC change

Browse source 
Commit 3e0272ca00 ('nl80211: Re-read MAC
address on RTM_NEWLINK') added the detection of external changes to MAC
address when the interface is brought up.

If the interface state is changed quickly enough, wpa_supplicant may
receive the netlink message for the !IFF_UP event when the interface
has already been brought up and would ignore the next netlink IFF_UP
message, missing the MAC change.

Fix this by also reloading the MAC address when a !IFF_UP event is
received with the interface up, because this implies that the
interface went down and up again, possibly changing the address.

Signed-off-by: Beniamino Galvani <bgalvani@redhat.com>
This commit is contained in:
Beniamino Galvani 2017-04-28 17:59:30 +02:00 committed by Jouni Malinen
parent 04f667fcdd
commit 290834df69
1 changed files with 27 additions and 20 deletions
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47
src/drivers/driver_nl80211.c
View file

@ -933,6 +933,30 @@ nl80211_find_drv(struct nl80211_global *global, int idx, u8 *buf, size_t len)
}
static void nl80211_refresh_mac(struct wpa_driver_nl80211_data *drv,
int ifindex)
{
struct i802_bss *bss;
u8 addr[ETH_ALEN];
bss = get_bss_ifindex(drv, ifindex);
if (bss &&
linux_get_ifhwaddr(drv->global->ioctl_sock,
bss->ifname, addr) < 0) {
wpa_printf(MSG_DEBUG,
"nl80211: %s: failed to re-read MAC address",
bss->ifname);
} else if (bss && os_memcmp(addr, bss->addr, ETH_ALEN) != 0) {
wpa_printf(MSG_DEBUG,
"nl80211: Own MAC address on ifindex %d (%s) changed from "
MACSTR " to " MACSTR,
ifindex, bss->ifname,
MAC2STR(bss->addr), MAC2STR(addr));
os_memcpy(bss->addr, addr, ETH_ALEN);
}
}
static void wpa_driver_nl80211_event_rtm_newlink(void *ctx,
struct ifinfomsg *ifi,
u8 *buf, size_t len)
@ -997,6 +1021,8 @@ static void wpa_driver_nl80211_event_rtm_newlink(void *ctx,
namebuf[0] = '\0';
if (if_indextoname(ifi->ifi_index, namebuf) &&
linux_iface_up(drv->global->ioctl_sock, namebuf) > 0) {
/* Re-read MAC address as it may have changed */
nl80211_refresh_mac(drv, ifi->ifi_index);
wpa_printf(MSG_DEBUG, "nl80211: Ignore interface down "
"event since interface %s is up", namebuf);
drv->ignore_if_down_event = 0;
@ -1044,27 +1070,8 @@ static void wpa_driver_nl80211_event_rtm_newlink(void *ctx,
"event since interface %s is marked "
"removed", drv->first_bss->ifname);
} else {
struct i802_bss *bss;
u8 addr[ETH_ALEN];
/* Re-read MAC address as it may have changed */
bss = get_bss_ifindex(drv, ifi->ifi_index);
if (bss &&
linux_get_ifhwaddr(drv->global->ioctl_sock,
bss->ifname, addr) < 0) {
wpa_printf(MSG_DEBUG,
"nl80211: %s: failed to re-read MAC address",
bss->ifname);
} else if (bss &&
os_memcmp(addr, bss->addr, ETH_ALEN) != 0) {
wpa_printf(MSG_DEBUG,
"nl80211: Own MAC address on ifindex %d (%s) changed from "
MACSTR " to " MACSTR,
ifi->ifi_index, bss->ifname,
MAC2STR(bss->addr),
MAC2STR(addr));
os_memcpy(bss->addr, addr, ETH_ALEN);
}
nl80211_refresh_mac(drv, ifi->ifi_index);
wpa_printf(MSG_DEBUG, "nl80211: Interface up");
drv->if_disabled = 0;