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linux-next/net/core
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Daniel Borkmann 5a5abb1fa3 tun, bpf: fix suspicious RCU usage in tun_{attach, detach}_filter 
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>
2016-04-01 14:33:46 -04:00
..
datagram.c net: Fix inverted test in __skb_recv_datagram 2015-12-08 11:30:17 -05:00
dev_addr_lists.c net: fix spelling for synchronized 2014-11-18 15:26:32 -05:00
dev_ioctl.c dev_ioctl: use sizeof(x) instead of sizeof x 2014-11-18 15:27:32 -05:00
dev.c net: add description for len argument of dev_get_phys_port_name 2016-03-21 13:28:31 -04:00
devlink.c Introduce devlink infrastructure 2016-03-01 16:07:29 -05:00
drop_monitor.c net: Replace get_cpu_var through this_cpu_ptr 2014-08-26 13:45:47 -04:00
dst_cache.c net: dst_cache_per_cpu_dst_set() can be static 2016-03-18 17:45:08 -04:00
dst.c net: add dst_cache to ovs vxlan lwtunnel 2016-02-16 20:21:48 -05:00
ethtool.c ethtool: Set cmd field in ETHTOOL_GLINKSETTINGS response to wrong nwords 2016-03-16 19:26:04 -04:00
fib_rules.c fib_rules: fix fib rule dumps across multiple skbs 2015-09-24 15:21:54 -07:00
filter.c tun, bpf: fix suspicious RCU usage in tun_{attach, detach}_filter 2016-04-01 14:33:46 -04:00
flow_dissector.c net/flow_dissector: Make dissector_uses_key() and skb_flow_dissector_target() public 2016-03-10 16:24:02 -05:00
flow.c flow: Move __get_hash_from_flowi{4,6} into flow_dissector.c 2015-09-01 17:00:24 -07:00
gen_estimator.c net: sched: Add description for cpu_bstats argument 2016-03-20 16:48:07 -04:00
gen_stats.c gen_stats.c: Add description for cpu argument 2016-03-20 16:48:06 -04:00
hwbm.c net: add a hardware buffer management helper API 2016-03-14 12:19:46 -04:00
link_watch.c dev: introduce dev_get_iflink() 2015-04-02 14:04:59 -04:00
lwtunnel.c lwtunnel: autoload of lwt modules 2016-02-21 22:00:28 -05:00
Makefile net: add a hardware buffer management helper API 2016-03-14 12:19:46 -04:00
neighbour.c net/neighbour: fix crash at dumping device-agnostic proxy entries 2015-12-03 00:07:51 -05:00
net_namespace.c netns: make nsid_lock per net 2015-05-17 23:41:11 -04:00
net-procfs.c rps: selective flow shedding during softnet overflow 2013-05-20 13:48:04 -07:00
net-sysfs.c net: core: use __ethtool_get_ksettings 2016-02-25 22:06:47 -05:00
net-sysfs.h net: netdev_kobject_init: annotate with __init 2014-01-05 20:27:54 -05:00
net-traces.c net: IPv6 fib lookup tracepoint 2015-11-22 11:54:10 -05:00
netclassid_cgroup.c core: remove unneded headers for net cgroup controllers. 2016-02-17 15:31:27 -05:00
netevent.c netevent: remove automatic variable in register_netevent_notifier() 2015-05-31 00:03:21 -07:00
netpoll.c netpoll: Fix extra refcount release in netpoll_cleanup() 2016-03-25 11:23:14 -04:00
netprio_cgroup.c core: remove unneded headers for net cgroup controllers. 2016-02-17 15:31:27 -05:00
pktgen.c net: pktgen: use reset to set mac header 2016-03-01 17:46:54 -05:00
ptp_classifier.c ptp: Change ptp_class to a proper bitmask 2015-11-03 11:08:22 -05:00
request_sock.c tcp: restore fastopen operations 2015-10-05 03:19:06 -07:00
rtnetlink.c rtnl: fix msg size calculation in if_nlmsg_size() 2016-03-31 16:49:54 -04:00
scm.c unix: correctly track in-flight fds in sending process user_struct 2016-02-08 10:30:42 -05:00
secure_seq.c net: remove a sparse error in secure_dccpv6_sequence_number() 2015-05-25 22:55:37 -04:00
skbuff.c net: remove a dubious unlikely() clause 2016-03-20 16:24:07 -04:00
sock_diag.c net: diag: Add the ability to destroy a socket. 2015-12-15 23:26:51 -05:00
sock_reuseport.c soreuseport: fix NULL ptr dereference SO_REUSEPORT after bind 2016-01-19 14:44:23 -05:00
sock.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2016-03-19 10:05:34 -07:00
stream.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2015-12-03 21:09:12 -05:00
sysctl_net_core.c net:Add sysctl_max_skb_frags 2016-02-09 04:28:06 -05:00
timestamping.c net: skb_defer_rx_timestamp should check for phydev before setting up classify 2015-07-09 14:17:15 -07:00
tso.c net: tso: add support for IPv6 2015-10-26 22:24:22 -07:00
utils.c net: move net_get_random_once to lib 2015-10-08 05:26:35 -07:00