Commit 3f2ab135 authored by Daniel Borkmann's avatar Daniel Borkmann Committed by David S. Miller

net: cls_bpf: fix auto generation of per list handles

When creating a bpf classifier in tc with priority collisions and
invoking automatic unique handle assignment, cls_bpf_grab_new_handle()
will return a wrong handle id which in fact is non-unique. Usually
altering of specific filters is being addressed over major id, but
in case of collisions we result in a filter chain, where handle ids
address individual cls_bpf_progs inside the classifier.

Issue is, in cls_bpf_grab_new_handle() we probe for head->hgen handle
in cls_bpf_get() and in case we found a free handle, we're supposed
to use exactly head->hgen. In case of insufficient numbers of handles,
we bail out later as handle id 0 is not allowed.

Fixes: 7d1d65cb ("net: sched: cls_bpf: add BPF-based classifier")
Signed-off-by: default avatarDaniel Borkmann <dborkman@redhat.com>
Acked-by: default avatarJiri Pirko <jiri@resnulli.us>
Acked-by: default avatarAlexei Starovoitov <ast@plumgrid.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 7913ecf6
......@@ -220,15 +220,21 @@ static u32 cls_bpf_grab_new_handle(struct tcf_proto *tp,
struct cls_bpf_head *head)
{
unsigned int i = 0x80000000;
u32 handle;
do {
if (++head->hgen == 0x7FFFFFFF)
head->hgen = 1;
} while (--i > 0 && cls_bpf_get(tp, head->hgen));
if (i == 0)
if (unlikely(i == 0)) {
pr_err("Insufficient number of handles\n");
handle = 0;
} else {
handle = head->hgen;
}
return i;
return handle;
}
static int cls_bpf_change(struct net *net, struct sk_buff *in_skb,
......
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