linux-toradex.git/net/sched, branch v4.9.2

sched: cls_flower: remove from hashtable only in case skip sw flag is not set

2016-11-30T01:44:38+00:00

Be symmetric to hashtable insert and remove filter from hashtable only
in case skip sw flag is not set.

Fixes: e69985c67c33 ("net/sched: cls_flower: Introduce support in SKIP SW flag")
Signed-off-by: Jiri Pirko 
Reviewed-by: Amir Vadai 
Signed-off-by: David S. Miller

net/sched: pedit: make sure that offset is valid

2016-11-30T00:46:00+00:00

Add a validation function to make sure offset is valid:
1. Not below skb head (could happen when offset is negative).
2. Validate both 'offset' and 'at'.

Signed-off-by: Amir Vadai 
Signed-off-by: David S. Miller

net, sched: respect rcu grace period on cls destruction

2016-11-28T15:47:35+00:00

Roi reported a crash in flower where tp->root was NULL in ->classify()
callbacks. Reason is that in ->destroy() tp->root is set to NULL via
RCU_INIT_POINTER(). It's problematic for some of the classifiers, because
this doesn't respect RCU grace period for them, and as a result, still
outstanding readers from tc_classify() will try to blindly dereference
a NULL tp->root.

The tp->root object is strictly private to the classifier implementation
and holds internal data the core such as tc_ctl_tfilter() doesn't know
about. Within some classifiers, such as cls_bpf, cls_basic, etc, tp->root
is only checked for NULL in ->get() callback, but nowhere else. This is
misleading and seemed to be copied from old classifier code that was not
cleaned up properly. For example, d3fa76ee6b4a ("[NET_SCHED]: cls_basic:
fix NULL pointer dereference") moved tp->root initialization into ->init()
routine, where before it was part of ->change(), so ->get() had to deal
with tp->root being NULL back then, so that was indeed a valid case, after
d3fa76ee6b4a, not really anymore. We used to set tp->root to NULL long
ago in ->destroy(), see 47a1a1d4be29 ("pkt_sched: remove unnecessary xchg()
in packet classifiers"); but the NULLifying was reintroduced with the
RCUification, but it's not correct for every classifier implementation.

In the cases that are fixed here with one exception of cls_cgroup, tp->root
object is allocated and initialized inside ->init() callback, which is always
performed at a point in time after we allocate a new tp, which means tp and
thus tp->root was not globally visible in the tp chain yet (see tc_ctl_tfilter()).
Also, on destruction tp->root is strictly kfree_rcu()'ed in ->destroy()
handler, same for the tp which is kfree_rcu()'ed right when we return
from ->destroy() in tcf_destroy(). This means, the head object's lifetime
for such classifiers is always tied to the tp lifetime. The RCU callback
invocation for the two kfree_rcu() could be out of order, but that's fine
since both are independent.

Dropping the RCU_INIT_POINTER(tp->root, NULL) for these classifiers here
means that 1) we don't need a useless NULL check in fast-path and, 2) that
outstanding readers of that tp in tc_classify() can still execute under
respect with RCU grace period as it is actually expected.

Things that haven't been touched here: cls_fw and cls_route. They each
handle tp->root being NULL in ->classify() path for historic reasons, so
their ->destroy() implementation can stay as is. If someone actually
cares, they could get cleaned up at some point to avoid the test in fast
path. cls_u32 doesn't set tp->root to NULL. For cls_rsvp, I just added a
!head should anyone actually be using/testing it, so it at least aligns with
cls_fw and cls_route. For cls_flower we additionally need to defer rhashtable
destruction (to a sleepable context) after RCU grace period as concurrent
readers might still access it. (Note that in this case we need to hold module
reference to keep work callback address intact, since we only wait on module
unload for all call_rcu()s to finish.)

This fixes one race to bring RCU grace period guarantees back. Next step
as worked on by Cong however is to fix 1e052be69d04 ("net_sched: destroy
proto tp when all filters are gone") to get the order of unlinking the tp
in tc_ctl_tfilter() for the RTM_DELTFILTER case right by moving
RCU_INIT_POINTER() before tcf_destroy() and let the notification for
removal be done through the prior ->delete() callback. Both are independant
issues. Once we have that right, we can then clean tp->root up for a number
of classifiers by not making them RCU pointers, which requires a new callback
(->uninit) that is triggered from tp's RCU callback, where we just kfree()
tp->root from there.

Fixes: 1f947bf151e9 ("net: sched: rcu'ify cls_bpf")
Fixes: 9888faefe132 ("net: sched: cls_basic use RCU")
Fixes: 70da9f0bf999 ("net: sched: cls_flow use RCU")
Fixes: 77b9900ef53a ("tc: introduce Flower classifier")
Fixes: bf3994d2ed31 ("net/sched: introduce Match-all classifier")
Fixes: 952313bd6258 ("net: sched: cls_cgroup use RCU")
Reported-by: Roi Dayan 
Signed-off-by: Daniel Borkmann 
Cc: Cong Wang 
Cc: John Fastabend 
Cc: Roi Dayan 
Cc: Jiri Pirko 
Acked-by: John Fastabend 
Acked-by: Cong Wang 
Signed-off-by: David S. Miller

net sched filters: fix filter handle ID in tfilter_notify_chain()

2016-11-24T21:05:58+00:00

Should pass valid filter handle, not the netlink flags.

Fixes: 30a391a13ab92 ("net sched filters: pass netlink message flags in event notification")
Signed-off-by: Roman Mashak 
Signed-off-by: Jamal Hadi Salim 
Reported-by: Cong Wang 
Acked-by: Daniel Borkmann 
Signed-off-by: David S. Miller

net sched filters: pass netlink message flags in event notification

2016-11-17T18:42:12+00:00

Userland client should be able to read an event, and reflect it back to
the kernel, therefore it needs to extract complete set of netlink flags.

For example, this will allow "tc monitor" to distinguish Add and Replace
operations.

Signed-off-by: Roman Mashak 
Signed-off-by: Jamal Hadi Salim 
Signed-off-by: David S. Miller

net_sched actions: use nla_parse_nested()

2016-10-29T19:01:01+00:00

Use nla_parse_nested instead of open-coding the call to
nla_parse() with the attribute data/len.

Signed-off-by: Johannes Berg 
Acked-by: Cong Wang 
Signed-off-by: David S. Miller

net sched filters: fix notification of filter delete with proper handle

2016-10-27T21:12:33+00:00

Daniel says:

While trying out [1][2], I noticed that tc monitor doesn't show the
correct handle on delete:

$ tc monitor
qdisc clsact ffff: dev eno1 parent ffff:fff1
filter dev eno1 ingress protocol all pref 49152 bpf handle 0x2a [...]
deleted filter dev eno1 ingress protocol all pref 49152 bpf handle 0xf3be0c80

some context to explain the above:
The user identity of any tc filter is represented by a 32-bit
identifier encoded in tcm->tcm_handle. Example 0x2a in the bpf filter
above. A user wishing to delete, get or even modify a specific filter
uses this handle to reference it.
Every classifier is free to provide its own semantics for the 32 bit handle.
Example: classifiers like u32 use schemes like 800:1:801 to describe
the semantics of their filters represented as hash table, bucket and
node ids etc.
Classifiers also have internal per-filter representation which is different
from this externally visible identity. Most classifiers set this
internal representation to be a pointer address (which allows fast retrieval
of said filters in their implementations). This internal representation
is referenced with the "fh" variable in the kernel control code.

When a user successfuly deletes a specific filter, by specifying the correct
tcm->tcm_handle, an event is generated to user space which indicates
which specific filter was deleted.

Before this patch, the "fh" value was sent to user space as the identity.
As an example what is shown in the sample bpf filter delete event above
is 0xf3be0c80. This is infact a 32-bit truncation of 0xffff8807f3be0c80
which happens to be a 64-bit memory address of the internal filter
representation (address of the corresponding filter's struct cls_bpf_prog);

After this patch the appropriate user identifiable handle as encoded
in the originating request tcm->tcm_handle is generated in the event.
One of the cardinal rules of netlink rules is to be able to take an
event (such as a delete in this case) and reflect it back to the
kernel and successfully delete the filter. This patch achieves that.

Note, this issue has existed since the original TC action
infrastructure code patch back in 2004 as found in:
https://git.kernel.org/cgit/linux/kernel/git/history/history.git/commit/

[1] http://patchwork.ozlabs.org/patch/682828/
[2] http://patchwork.ozlabs.org/patch/682829/

Fixes: 4e54c4816bfe ("[NET]: Add tc extensions infrastructure.")
Reported-by: Daniel Borkmann 
Acked-by: Cong Wang 
Signed-off-by: Jamal Hadi Salim 
Signed-off-by: David S. Miller

net/sched: act_mirred: Use passed lastuse argument

2016-10-20T15:14:24+00:00

stats_update callback is called by NIC drivers doing hardware
offloading of the mirred action. Lastuse is passed as argument
to specify when the stats was actually last updated and is not
always the current time.

Fixes: 9798e6fe4f9b ('net: act_mirred: allow statistic updates from offloaded actions')
Signed-off-by: Paul Blakey 
Signed-off-by: Or Gerlitz 
Signed-off-by: David S. Miller

net_sched: reorder pernet ops and act ops registrations

2016-10-13T14:26:43+00:00

Krister reported a kernel NULL pointer dereference after
tcf_action_init_1() invokes a_o->init(), it is a race condition
where one thread calling tcf_register_action() to initialize
the netns data after putting act ops in the global list and
the other thread searching the list and then calling
a_o->init(net, ...).

Fix this by moving the pernet ops registration before making
the action ops visible. This is fine because: a) we don't
rely on act_base in pernet ops->init(), b) in the worst case we
have a fully initialized netns but ops is still not ready so
new actions still can't be created.

Reported-by: Krister Johansen 
Tested-by: Krister Johansen 
Cc: Jamal Hadi Salim 
Signed-off-by: Cong Wang 
Acked-by: Jamal Hadi Salim 
Signed-off-by: David S. Miller

net_sched: do not broadcast RTM_GETTFILTER result

2016-10-13T13:51:55+00:00

There are two ways to get tc filters from kernel to user space.

1) Full dump (tc_dump_tfilter())
2) RTM_GETTFILTER to get one precise filter, reducing overhead.

The second operation is unfortunately broadcasting its result,
polluting "tc monitor" users.

This patch makes sure only the requester gets the result, using
netlink_unicast() instead of rtnetlink_send()

Jamal cooked an iproute2 patch to implement "tc filter get" operation,
but other user space libraries already use RTM_GETTFILTER when a single
filter is queried, instead of dumping all filters.

Signed-off-by: Eric Dumazet 
Cc: Jamal Hadi Salim 
Acked-by: Jamal Hadi Salim 
Signed-off-by: David S. Miller