From c08e0be44759d0b5affc5888be4aa5e536873335 Mon Sep 17 00:00:00 2001 From: Jeimon Date: Sat, 8 May 2021 11:52:30 +0800 Subject: net/nfc/rawsock.c: fix a permission check bug [ Upstream commit 8ab78863e9eff11910e1ac8bcf478060c29b379e ] The function rawsock_create() calls a privileged function sk_alloc(), which requires a ns-aware check to check net->user_ns, i.e., ns_capable(). However, the original code checks the init_user_ns using capable(). So we replace the capable() with ns_capable(). Signed-off-by: Jeimon Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/nfc/rawsock.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net') diff --git a/net/nfc/rawsock.c b/net/nfc/rawsock.c index 92a3cfae4de8..2fba626a0125 100644 --- a/net/nfc/rawsock.c +++ b/net/nfc/rawsock.c @@ -345,7 +345,7 @@ static int rawsock_create(struct net *net, struct socket *sock, return -ESOCKTNOSUPPORT; if (sock->type == SOCK_RAW) { - if (!capable(CAP_NET_RAW)) + if (!ns_capable(net->user_ns, CAP_NET_RAW)) return -EPERM; sock->ops = &rawsock_raw_ops; } else { -- cgit v1.2.3 From 5f155c4046200f067b1dc3140ea99ef56e4e0b74 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Mon, 17 May 2021 16:38:09 +0200 Subject: netlink: disable IRQs for netlink_lock_table() [ Upstream commit 1d482e666b8e74c7555dbdfbfb77205eeed3ff2d ] Syzbot reports that in mac80211 we have a potential deadlock between our "local->stop_queue_reasons_lock" (spinlock) and netlink's nl_table_lock (rwlock). This is because there's at least one situation in which we might try to send a netlink message with this spinlock held while it is also possible to take the spinlock from a hardirq context, resulting in the following deadlock scenario reported by lockdep: CPU0 CPU1 ---- ---- lock(nl_table_lock); local_irq_disable(); lock(&local->queue_stop_reason_lock); lock(nl_table_lock); lock(&local->queue_stop_reason_lock); This seems valid, we can take the queue_stop_reason_lock in any kind of context ("CPU0"), and call ieee80211_report_ack_skb() with the spinlock held and IRQs disabled ("CPU1") in some code path (ieee80211_do_stop() via ieee80211_free_txskb()). Short of disallowing netlink use in scenarios like these (which would be rather complex in mac80211's case due to the deep callchain), it seems the only fix for this is to disable IRQs while nl_table_lock is held to avoid hitting this scenario, this disallows the "CPU0" portion of the reported deadlock. Note that the writer side (netlink_table_grab()) already disables IRQs for this lock. Unfortunately though, this seems like a huge hammer, and maybe the whole netlink table locking should be reworked. Reported-by: syzbot+69ff9dff50dcfe14ddd4@syzkaller.appspotmail.com Signed-off-by: Johannes Berg Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/netlink/af_netlink.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'net') diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index cc37a219e11e..c20c41801845 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -436,11 +436,13 @@ void netlink_table_ungrab(void) static inline void netlink_lock_table(void) { + unsigned long flags; + /* read_lock() synchronizes us to netlink_table_grab */ - read_lock(&nl_table_lock); + read_lock_irqsave(&nl_table_lock, flags); atomic_inc(&nl_table_users); - read_unlock(&nl_table_lock); + read_unlock_irqrestore(&nl_table_lock, flags); } static inline void -- cgit v1.2.3