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authorMathieu Xhonneux <m.xhonneux@gmail.com>2018-07-26 05:10:40 +0300
committerDaniel Borkmann <daniel@iogearbox.net>2018-07-31 10:22:48 +0300
commit486cdf21583e5b1fad488a3e4f0a5242a31c0ffa (patch)
tree937b2025eb9d704b9e517ecbbc2fc3705e1863e4 /net/ipv6
parent1ce6a9fc154935d9db771173ecde03fa9b42df4a (diff)
downloadlinux-486cdf21583e5b1fad488a3e4f0a5242a31c0ffa.tar.xz
bpf: add End.DT6 action to bpf_lwt_seg6_action helper
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 <m.xhonneux@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'net/ipv6')
-rw-r--r--net/ipv6/seg6_local.c50
1 files changed, 32 insertions, 18 deletions
diff --git a/net/ipv6/seg6_local.c b/net/ipv6/seg6_local.c
index e1025b493a18..60325dbfe88b 100644
--- a/net/ipv6/seg6_local.c
+++ b/net/ipv6/seg6_local.c
@@ -459,36 +459,57 @@ drop:
DEFINE_PER_CPU(struct seg6_bpf_srh_state, seg6_bpf_srh_states);
+bool seg6_bpf_has_valid_srh(struct sk_buff *skb)
+{
+ struct seg6_bpf_srh_state *srh_state =
+ this_cpu_ptr(&seg6_bpf_srh_states);
+ struct ipv6_sr_hdr *srh = srh_state->srh;
+
+ if (unlikely(srh == NULL))
+ return false;
+
+ if (unlikely(!srh_state->valid)) {
+ if ((srh_state->hdrlen & 7) != 0)
+ return false;
+
+ srh->hdrlen = (u8)(srh_state->hdrlen >> 3);
+ if (!seg6_validate_srh(srh, (srh->hdrlen + 1) << 3))
+ return false;
+
+ srh_state->valid = true;
+ }
+
+ return true;
+}
+
static int input_action_end_bpf(struct sk_buff *skb,
struct seg6_local_lwt *slwt)
{
struct seg6_bpf_srh_state *srh_state =
this_cpu_ptr(&seg6_bpf_srh_states);
- struct seg6_bpf_srh_state local_srh_state;
struct ipv6_sr_hdr *srh;
- int srhoff = 0;
int ret;
srh = get_and_validate_srh(skb);
- if (!srh)
- goto drop;
+ if (!srh) {
+ kfree_skb(skb);
+ return -EINVAL;
+ }
advance_nextseg(srh, &ipv6_hdr(skb)->daddr);
/* preempt_disable is needed to protect the per-CPU buffer srh_state,
* which is also accessed by the bpf_lwt_seg6_* helpers
*/
preempt_disable();
+ srh_state->srh = srh;
srh_state->hdrlen = srh->hdrlen << 3;
- srh_state->valid = 1;
+ srh_state->valid = true;
rcu_read_lock();
bpf_compute_data_pointers(skb);
ret = bpf_prog_run_save_cb(slwt->bpf.prog, skb);
rcu_read_unlock();
- local_srh_state = *srh_state;
- preempt_enable();
-
switch (ret) {
case BPF_OK:
case BPF_REDIRECT:
@@ -500,24 +521,17 @@ static int input_action_end_bpf(struct sk_buff *skb,
goto drop;
}
- if (unlikely((local_srh_state.hdrlen & 7) != 0))
- goto drop;
-
- if (ipv6_find_hdr(skb, &srhoff, IPPROTO_ROUTING, NULL, NULL) < 0)
- goto drop;
- srh = (struct ipv6_sr_hdr *)(skb->data + srhoff);
- srh->hdrlen = (u8)(local_srh_state.hdrlen >> 3);
-
- if (!local_srh_state.valid &&
- unlikely(!seg6_validate_srh(srh, (srh->hdrlen + 1) << 3)))
+ if (srh_state->srh && !seg6_bpf_has_valid_srh(skb))
goto drop;
+ preempt_enable();
if (ret != BPF_REDIRECT)
seg6_lookup_nexthop(skb, NULL, 0);
return dst_input(skb);
drop:
+ preempt_enable();
kfree_skb(skb);
return -EINVAL;
}