diff mbox series

[net,03/13] net: sched: cls_u32: disallow linking to root hnode

Message ID 20180909013132.3222-4-viro@ZenIV.linux.org.uk
State Changes Requested, archived
Delegated to: David Miller
Headers show
Series cls_u32 cleanups and fixes. | expand

Commit Message

Al Viro Sept. 9, 2018, 1:31 a.m. UTC 
From: Al Viro <viro@zeniv.linux.org.uk>

Operation makes no sense.  Nothing will actually break if we do so
(depth limit in u32_classify() will prevent infinite loops), but
according to maintainers it's best prohibited outright.

NOTE: doing so guarantees that u32_destroy() will trigger the call
of u32_destroy_hnode(); we might want to make that unconditional.

Test:
tc qdisc add dev eth0 ingress
tc filter add dev eth0 parent ffff: protocol ip prio 100 u32 \
	link 800: offset at 0 mask 0f00 shift 6 plus 0 eat match ip protocol 6 ff
should fail with
Error: cls_u32: Not linking to root node

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 net/sched/cls_u32.c | 4 ++++
 1 file changed, 4 insertions(+)

Comments

Jamal Hadi Salim Sept. 9, 2018, 11:39 a.m. UTC | #1 
On 2018-09-08 9:31 p.m., Al Viro wrote:
> From: Al Viro <viro@zeniv.linux.org.uk>
> 
> Operation makes no sense.  Nothing will actually break if we do so
> (depth limit in u32_classify() will prevent infinite loops), but
> according to maintainers it's best prohibited outright.
> 
> NOTE: doing so guarantees that u32_destroy() will trigger the call
> of u32_destroy_hnode(); we might want to make that unconditional.
> 
> Test:
> tc qdisc add dev eth0 ingress
> tc filter add dev eth0 parent ffff: protocol ip prio 100 u32 \
> 	link 800: offset at 0 mask 0f00 shift 6 plus 0 eat match ip protocol 6 ff
> should fail with
> Error: cls_u32: Not linking to root node
> 
> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Tested-by: Jamal Hadi Salim <jhs@mojatatu.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>

cheers,
jamal
diff mbox series

Patch

diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c
index c4782aa808c7..72459b09d910 100644
--- a/net/sched/cls_u32.c
+++ b/net/sched/cls_u32.c
@@ -797,6 +797,10 @@  static int u32_set_parms(struct net *net, struct tcf_proto *tp,
 				NL_SET_ERR_MSG_MOD(extack, "Link hash table not found");
 				return -EINVAL;
 			}
+			if (ht_down->is_root) {
+				NL_SET_ERR_MSG_MOD(extack, "Not linking to root node");
+				return -EINVAL;
+			}
 			ht_down->refcnt++;
 		}