| From | Luis Henriques <> | Subject | [PATCH 3.16.y-ckt 100/165] net: cls_bpf: fix auto generation of per list handles | Date | Wed, 25 Mar 2015 14:01:13 +0000 |
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3.16.7-ckt9 -stable review patch. If anyone has any objections, please let me know.
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From: Daniel Borkmann <dborkman@redhat.com>
commit 3f2ab135946dcd4eb6af92a53d6d4bd35e7526ca upstream.
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: 7d1d65cb84e1 ("net: sched: cls_bpf: add BPF-based classifier") Signed-off-by: Daniel Borkmann <dborkman@redhat.com> Acked-by: Jiri Pirko <jiri@resnulli.us> Acked-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- net/sched/cls_bpf.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/net/sched/cls_bpf.c b/net/sched/cls_bpf.c index 87f2f1b17181..d2f034cf6055 100644 --- a/net/sched/cls_bpf.c +++ b/net/sched/cls_bpf.c @@ -233,15 +233,21 @@ 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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