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authorDaniel Borkmann <daniel@iogearbox.net>2016-07-03 01:28:47 +0200
committerDavid S. Miller <davem@davemloft.net>2016-07-04 16:08:40 -0700
commit13c5c240f789bbd2bcacb14a23771491485ae61f (patch)
treeecf47dfa74f483b539c325e1b95d3772e38e0107 /net/core
parent6fd980ac39efee9c26b1eb256c3271fcb139bd99 (diff)
bpf: add bpf_get_hash_recalc helper
If skb_clear_hash() was invoked due to mangling of relevant headers and BPF program needs skb->hash later on, we can add a helper to trigger hash recalculation via bpf_get_hash_recalc(). The helper will return the newly retrieved hash directly, but later access can also be done via skb context again through skb->hash directly (inline) without needing to call the helper once more. 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.c19
1 files changed, 19 insertions, 0 deletions
diff --git a/net/core/filter.c b/net/core/filter.c
index 54071cf70fb5..10c4a2f9e8bb 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -1729,6 +1729,23 @@ static const struct bpf_func_proto bpf_get_route_realm_proto = {
.arg1_type = ARG_PTR_TO_CTX,
};
+static u64 bpf_get_hash_recalc(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
+{
+ /* If skb_clear_hash() was called due to mangling, we can
+ * trigger SW recalculation here. Later access to hash
+ * can then use the inline skb->hash via context directly
+ * instead of calling this helper again.
+ */
+ return skb_get_hash((struct sk_buff *) (unsigned long) r1);
+}
+
+static const struct bpf_func_proto bpf_get_hash_recalc_proto = {
+ .func = bpf_get_hash_recalc,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_CTX,
+};
+
static u64 bpf_skb_vlan_push(u64 r1, u64 r2, u64 vlan_tci, u64 r4, u64 r5)
{
struct sk_buff *skb = (struct sk_buff *) (long) r1;
@@ -2337,6 +2354,8 @@ tc_cls_act_func_proto(enum bpf_func_id func_id)
return &bpf_redirect_proto;
case BPF_FUNC_get_route_realm:
return &bpf_get_route_realm_proto;
+ case BPF_FUNC_get_hash_recalc:
+ return &bpf_get_hash_recalc_proto;
case BPF_FUNC_perf_event_output:
return bpf_get_event_output_proto();
case BPF_FUNC_get_smp_processor_id: