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authorDaniel Borkmann <daniel@iogearbox.net>2020-06-02 16:58:33 +0200
committerAlexei Starovoitov <ast@kernel.org>2020-06-02 11:50:23 -0700
commit7cdec54f9713256bb170873a1fc5c75c9127c9d2 (patch)
tree2de575e883f9cb33b9722b135a4a54c352cdb984 /net
parent836e66c218f355ec01ba57671c85abf32961dcea (diff)
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.c38
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: