diff options
| author | Daniel Borkmann <daniel@iogearbox.net> | 2016-06-28 12:18:28 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-06-30 05:54:40 -0400 |
| commit | d2485c4242a826fdf493fd3a27b8b792965b9b9e (patch) | |
| tree | d02f10ddd1ad1f4e5d280ab8e285f7ab450312fc /net/core | |
| parent | 6578171a7ff0c31dc73258f93da7407510abf085 (diff) | |
| download | linux-d2485c4242a826fdf493fd3a27b8b792965b9b9e.tar.bz2 | |
bpf: add bpf_skb_change_type helper
This work adds a helper for changing skb->pkt_type in a controlled way.
We only allow a subset of possible values and can extend that in future
should other use cases come up. Doing this as a helper has the advantage
that errors can be handeled gracefully and thus helper kept extensible.
It's a write counterpart to pkt_type member we can already read from
struct __sk_buff context. Major use case is to change incoming skbs to
PACKET_HOST in a programmatic way instead of having to recirculate via
redirect(..., BPF_F_INGRESS), for example.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core')
| -rw-r--r-- | net/core/filter.c | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/net/core/filter.c b/net/core/filter.c index d983e765787a..76f9a4938be4 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -1979,6 +1979,28 @@ static const struct bpf_func_proto bpf_skb_change_proto_proto = { .arg3_type = ARG_ANYTHING, }; +static u64 bpf_skb_change_type(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5) +{ + struct sk_buff *skb = (struct sk_buff *) (long) r1; + u32 pkt_type = r2; + + /* We only allow a restricted subset to be changed for now. */ + if (unlikely(skb->pkt_type > PACKET_OTHERHOST || + pkt_type > PACKET_OTHERHOST)) + return -EINVAL; + + skb->pkt_type = pkt_type; + return 0; +} + +static const struct bpf_func_proto bpf_skb_change_type_proto = { + .func = bpf_skb_change_type, + .gpl_only = false, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_CTX, + .arg2_type = ARG_ANYTHING, +}; + bool bpf_helper_changes_skb_data(void *func) { if (func == bpf_skb_vlan_push) @@ -2278,6 +2300,8 @@ tc_cls_act_func_proto(enum bpf_func_id func_id) return &bpf_skb_vlan_pop_proto; case BPF_FUNC_skb_change_proto: return &bpf_skb_change_proto_proto; + case BPF_FUNC_skb_change_type: + return &bpf_skb_change_type_proto; case BPF_FUNC_skb_get_tunnel_key: return &bpf_skb_get_tunnel_key_proto; case BPF_FUNC_skb_set_tunnel_key: |