Daniel Borkmann e137eeb38d tun, bpf: fix suspicious RCU usage in tun_{attach, detach}_filter ... [ Upstream commit 5a5abb1fa3 ] Sasha Levin reported a suspicious rcu_dereference_protected() warning found while fuzzing with trinity that is similar to this one: [ 52.765684] net/core/filter.c:2262 suspicious rcu_dereference_protected() usage! [ 52.765688] other info that might help us debug this: [ 52.765695] rcu_scheduler_active = 1, debug_locks = 1 [ 52.765701] 1 lock held by a.out/1525: [ 52.765704] #0: (rtnl_mutex){+.+.+.}, at: [<ffffffff816a64b7>] rtnl_lock+0x17/0x20 [ 52.765721] stack backtrace: [ 52.765728] CPU: 1 PID: 1525 Comm: a.out Not tainted 4.5.0+ #264 [...] [ 52.765768] Call Trace: [ 52.765775] [<ffffffff813e488d>] dump_stack+0x85/0xc8 [ 52.765784] [<ffffffff810f2fa5>] lockdep_rcu_suspicious+0xd5/0x110 [ 52.765792] [<ffffffff816afdc2>] sk_detach_filter+0x82/0x90 [ 52.765801] [<ffffffffa0883425>] tun_detach_filter+0x35/0x90 [tun] [ 52.765810] [<ffffffffa0884ed4>] __tun_chr_ioctl+0x354/0x1130 [tun] [ 52.765818] [<ffffffff8136fed0>] ? selinux_file_ioctl+0x130/0x210 [ 52.765827] [<ffffffffa0885ce3>] tun_chr_ioctl+0x13/0x20 [tun] [ 52.765834] [<ffffffff81260ea6>] do_vfs_ioctl+0x96/0x690 [ 52.765843] [<ffffffff81364af3>] ? security_file_ioctl+0x43/0x60 [ 52.765850] [<ffffffff81261519>] SyS_ioctl+0x79/0x90 [ 52.765858] [<ffffffff81003ba2>] do_syscall_64+0x62/0x140 [ 52.765866] [<ffffffff817d563f>] entry_SYSCALL64_slow_path+0x25/0x25 Same can be triggered with PROVE_RCU (+ PROVE_RCU_REPEATEDLY) enabled from tun_attach_filter() when user space calls ioctl(tun_fd, TUN{ATTACH, DETACH}FILTER, ...) for adding/removing a BPF filter on tap devices. Since the fix in f91ff5b9ff ("net: sk_{detach|attach}_filter() rcu fixes") sk_attach_filter()/sk_detach_filter() now dereferences the filter with rcu_dereference_protected(), checking whether socket lock is held in control path. Since its introduction in 9940516259 ("tun: socket filter support"), tap filters are managed under RTNL lock from __tun_chr_ioctl(). Thus the sock_owned_by_user(sk) doesn't apply in this specific case and therefore triggers the false positive. Extend the BPF API with __sk_attach_filter()/__sk_detach_filter() pair that is used by tap filters and pass in lockdep_rtnl_is_held() for the rcu_dereference_protected() checks instead. Reported-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2016-04-20 15:42:06 +09:00
..
acpi	Merge branch 'acpi-pci'	2015-11-07 01:30:10 +01:00
asm-generic	bitops: Do not default to __clear_bit() for __clear_bit_unlock()	2016-04-12 09:09:00 -07:00
clocksource
crypto	crypto: af_alg - Allow af_af_alg_release_parent to be called on nokey path	2016-02-17 12:31:03 -08:00
drm	drm: add helper to check for wc memory support	2016-03-03 15:07:21 -08:00
dt-bindings	ARM: DT updates for v4.4	2015-11-10 15:06:26 -08:00
keys
kvm	KVM: arm/arm64: arch_timer: Preserve physical dist. active state on LR.active	2015-11-24 18:07:40 +01:00
linux	tun, bpf: fix suspicious RCU usage in tun_{attach, detach}_filter	2016-04-20 15:42:06 +09:00
math-emu
media
memory
misc
net	bonding: fix bond_get_stats()	2016-04-20 15:42:04 +09:00
pcmcia
ras
rdma	IB/mad: Require CM send method for everything except ClassPortInfo	2015-12-08 12:19:11 -05:00
rxrpc
scsi	Merge branch 'mkp-fixes' into fixes	2015-12-03 09:32:33 -08:00
soc	ARM: SoC driver updates for v4.4	2015-11-10 15:00:03 -08:00
sound	ALSA: rawmidi: Make snd_rawmidi_transmit() race-free	2016-02-17 12:30:58 -08:00
target	target: Fix WRITE_SAME/DISCARD conversion to linux 512b sectors	2016-03-09 15:34:51 -08:00
trace	Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux	2015-11-11 09:03:01 -08:00
uapi	uapi: update install list after nvme.h rename	2016-03-03 15:07:24 -08:00
video	gpu: ipu-v3: drop unused dmfc field from client platform data	2015-11-24 11:30:15 +01:00
xen	xen: Add RING_COPY_REQUEST()	2015-12-18 10:00:17 -05:00
Kbuild