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bpf: wire in data and data_end for cls_act_bpf

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allow cls_bpf and act_bpf programs access skb->data and skb->data_end pointers.
The bpf helpers that change skb->data need to update data_end pointer as well.
The verifier checks that programs always reload data, data_end pointers
after calls to such bpf helpers.
We cannot add 'data_end' pointer to struct qdisc_skb_cb directly,
since it's embedded as-is by infiniband ipoib, so wrapper struct is needed.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexei Starovoitov
2016-05-05 19:49:12 -07:00
committed by David S. Miller
parent 735b433397
commit db58ba4592
4 changed files with 65 additions and 6 deletions
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16
include/linux/filter.h
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@ -352,6 +352,22 @@ struct sk_filter {
#define BPF_SKB_CB_LEN QDISC_CB_PRIV_LEN
struct bpf_skb_data_end {
struct qdisc_skb_cb qdisc_cb;
void *data_end;
};
/* compute the linear packet data range [data, data_end) which
* will be accessed by cls_bpf and act_bpf programs
*/
static inline void bpf_compute_data_end(struct sk_buff *skb)
{
struct bpf_skb_data_end *cb = (struct bpf_skb_data_end *)skb->cb;
BUILD_BUG_ON(sizeof(*cb) > FIELD_SIZEOF(struct sk_buff, cb));
cb->data_end = skb->data + skb_headlen(skb);
}
static inline u8 *bpf_skb_cb(struct sk_buff *skb)
{
/* eBPF programs may read/write skb->cb[] area to transfer meta