The seg6local LWT provides the End.DT6 action, which allows to
decapsulate an outer IPv6 header containing a Segment Routing Header
(SRH), full specification is available here:
https://tools.ietf.org/html/draft-filsfils-spring-srv6-network-programming-05
This patch adds this action now to the seg6local BPF
interface. Since it is not mandatory that the inner IPv6 header also
contains a SRH, seg6_bpf_srh_state has been extended with a pointer to
a possible SRH of the outermost IPv6 header. This helps assessing if the
validation must be triggered or not, and avoids some calls to
ipv6_find_hdr.
v3: s/1/true, s/0/false for boolean values
v2: - changed true/false -> 1/0
- preempt_enable no longer called in first conditional block
Signed-off-by: Mathieu Xhonneux
---
include/net/seg6_local.h | 4 ++-
net/core/filter.c| 89
net/ipv6/seg6_local.c| 50 +--
3 files changed, 95 insertions(+), 48 deletions(-)
diff --git a/include/net/seg6_local.h b/include/net/seg6_local.h
index 661fd5b4d3e0..08359e2d8b35 100644
--- a/include/net/seg6_local.h
+++ b/include/net/seg6_local.h
@@ -21,10 +21,12 @@
extern int seg6_lookup_nexthop(struct sk_buff *skb, struct in6_addr *nhaddr,
u32 tbl_id);
+extern bool seg6_bpf_has_valid_srh(struct sk_buff *skb);
struct seg6_bpf_srh_state {
- bool valid;
+ struct ipv6_sr_hdr *srh;
u16 hdrlen;
+ bool valid;
};
DECLARE_PER_CPU(struct seg6_bpf_srh_state, seg6_bpf_srh_states);
diff --git a/net/core/filter.c b/net/core/filter.c
index 104d560946da..355430cfeb76 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -4542,26 +4542,28 @@ BPF_CALL_4(bpf_lwt_seg6_store_bytes, struct sk_buff *,
skb, u32, offset,
{
struct seg6_bpf_srh_state *srh_state =
this_cpu_ptr(_bpf_srh_states);
+ struct ipv6_sr_hdr *srh = srh_state->srh;
void *srh_tlvs, *srh_end, *ptr;
- struct ipv6_sr_hdr *srh;
int srhoff = 0;
- if (ipv6_find_hdr(skb, , IPPROTO_ROUTING, NULL, NULL) < 0)
+ if (srh == NULL)
return -EINVAL;
- srh = (struct ipv6_sr_hdr *)(skb->data + srhoff);
srh_tlvs = (void *)((char *)srh + ((srh->first_segment + 1) << 4));
srh_end = (void *)((char *)srh + sizeof(*srh) + srh_state->hdrlen);
ptr = skb->data + offset;
if (ptr >= srh_tlvs && ptr + len <= srh_end)
- srh_state->valid = 0;
+ srh_state->valid = false;
else if (ptr < (void *)>flags ||
ptr + len > (void *)>segments)
return -EFAULT;
if (unlikely(bpf_try_make_writable(skb, offset + len)))
return -EFAULT;
+ if (ipv6_find_hdr(skb, , IPPROTO_ROUTING, NULL, NULL) < 0)
+ return -EINVAL;
+ srh_state->srh = (struct ipv6_sr_hdr *)(skb->data + srhoff);
memcpy(skb->data + offset, from, len);
return 0;
@@ -4577,52 +4579,79 @@ static const struct bpf_func_proto
bpf_lwt_seg6_store_bytes_proto = {
.arg4_type = ARG_CONST_SIZE
};
-BPF_CALL_4(bpf_lwt_seg6_action, struct sk_buff *, skb,
- u32, action, void *, param, u32, param_len)
+static void bpf_update_srh_state(struct sk_buff *skb)
{
struct seg6_bpf_srh_state *srh_state =
this_cpu_ptr(_bpf_srh_states);
- struct ipv6_sr_hdr *srh;
int srhoff = 0;
- int err;
-
- if (ipv6_find_hdr(skb, , IPPROTO_ROUTING, NULL, NULL) < 0)
- return -EINVAL;
- srh = (struct ipv6_sr_hdr *)(skb->data + srhoff);
-
- if (!srh_state->valid) {
- if (unlikely((srh_state->hdrlen & 7) != 0))
- return -EBADMSG;
-
- srh->hdrlen = (u8)(srh_state->hdrlen >> 3);
- if (unlikely(!seg6_validate_srh(srh, (srh->hdrlen + 1) << 3)))
- return -EBADMSG;
- srh_state->valid = 1;
+ if (ipv6_find_hdr(skb, , IPPROTO_ROUTING, NULL, NULL) < 0) {
+ srh_state->srh = NULL;
+ } else {
+ srh_state->srh = (struct ipv6_sr_hdr *)(skb->data + srhoff);
+ srh_state->hdrlen = srh_state->srh->hdrlen << 3;
+ srh_state->valid = true;
}
+}
+
+BPF_CALL_4(bpf_lwt_seg6_action, struct sk_buff *, skb,
+ u32, action, void *, param, u32, param_len)
+{
+ struct seg6_bpf_srh_state *srh_state =
+ this_cpu_ptr(_bpf_srh_states);
+ int hdroff = 0;
+ int err;
switch (action) {
case SEG6_LOCAL_ACTION_END_X:
+ if (!seg6_bpf_has_valid_srh(skb))
+ return -EBADMSG;
if (param_len != sizeof(struct in6_addr))
return -EINVAL;
return seg6_lookup_nexthop(skb, (struct in6_addr *)param, 0);
case SEG6_LOCAL_ACTION_END_T:
+ if
