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| author |   Daniel Borkmann <daniel@iogearbox.net> | 2020-06-02 16:58:33 +0200 |
|---|---|---|
| committer |   Alexei Starovoitov <ast@kernel.org> | 2020-06-02 11:50:23 -0700 |
| commit | 7cdec54f9713256bb170873a1fc5c75c9127c9d2 (patch) | |
| tree | 2de575e883f9cb33b9722b135a4a54c352cdb984 /net | |
| parent | bpf: Fix up bpf_skb_adjust_room helper's skb csum setting (diff) | |
| download | wireguard-linux-7cdec54f9713256bb170873a1fc5c75c9127c9d2.tar.xz wireguard-linux-7cdec54f9713256bb170873a1fc5c75c9127c9d2.zip | |
bpf: Add csum_level helper for fixing up csum levels
Add a bpf_csum_level() helper which BPF programs can use in combination
with bpf_skb_adjust_room() when they pass in BPF_F_ADJ_ROOM_NO_CSUM_RESET
flag to the latter to avoid falling back to CHECKSUM_NONE.
The bpf_csum_level() allows to adjust CHECKSUM_UNNECESSARY skb->csum_levels
via BPF_CSUM_LEVEL_{INC,DEC} which calls __skb_{incr,decr}_checksum_unnecessary()
on the skb. The helper also allows a BPF_CSUM_LEVEL_RESET which sets the skb's
csum to CHECKSUM_NONE as well as a BPF_CSUM_LEVEL_QUERY to just return the
current level. Without this helper, there is no way to otherwise adjust the
skb->csum_level. I did not add an extra dummy flags as there is plenty of free
bitspace in level argument itself iff ever needed in future.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Alan Maguire <alan.maguire@oracle.com>
Acked-by: Lorenz Bauer <lmb@cloudflare.com>
Link: https://lore.kernel.org/bpf/279ae3717cb3d03c0ffeb511493c93c450a01e1a.1591108731.git.daniel@iogearbox.net
Diffstat (limited to 'net')
| -rw-r--r-- | net/core/filter.c | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/net/core/filter.c b/net/core/filter.c index 278dcc0af961..d01a244b5087 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -2015,6 +2015,40 @@ static const struct bpf_func_proto bpf_csum_update_proto = { .arg2_type = ARG_ANYTHING, }; +BPF_CALL_2(bpf_csum_level, struct sk_buff *, skb, u64, level) +{ + /* The interface is to be used in combination with bpf_skb_adjust_room() + * for encap/decap of packet headers when BPF_F_ADJ_ROOM_NO_CSUM_RESET + * is passed as flags, for example. + */ + switch (level) { + case BPF_CSUM_LEVEL_INC: + __skb_incr_checksum_unnecessary(skb); + break; + case BPF_CSUM_LEVEL_DEC: + __skb_decr_checksum_unnecessary(skb); + break; + case BPF_CSUM_LEVEL_RESET: + __skb_reset_checksum_unnecessary(skb); + break; + case BPF_CSUM_LEVEL_QUERY: + return skb->ip_summed == CHECKSUM_UNNECESSARY ? + skb->csum_level : -EACCES; + default: + return -EINVAL; + } + + return 0; +} + +static const struct bpf_func_proto bpf_csum_level_proto = { + .func = bpf_csum_level, + .gpl_only = false, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_CTX, + .arg2_type = ARG_ANYTHING, +}; + static inline int __bpf_rx_skb(struct net_device *dev, struct sk_buff *skb) { return dev_forward_skb(dev, skb); @@ -6280,6 +6314,8 @@ tc_cls_act_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_csum_diff_proto; case BPF_FUNC_csum_update: return &bpf_csum_update_proto; + case BPF_FUNC_csum_level: + return &bpf_csum_level_proto; case BPF_FUNC_l3_csum_replace: return &bpf_l3_csum_replace_proto; case BPF_FUNC_l4_csum_replace: @@ -6613,6 +6649,8 @@ lwt_xmit_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_skb_store_bytes_proto; case BPF_FUNC_csum_update: return &bpf_csum_update_proto; + case BPF_FUNC_csum_level: + return &bpf_csum_level_proto; case BPF_FUNC_l3_csum_replace: return &bpf_l3_csum_replace_proto; case BPF_FUNC_l4_csum_replace: |