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Message-Id: <20180710165402.26605-1-m.xhonneux@gmail.com>
Date: Tue, 10 Jul 2018 16:54:02 +0000
From: Mathieu Xhonneux <m.xhonneux@...il.com>
To: netdev@...r.kernel.org
Cc: daniel@...earbox.net, alexei.starovoitov@...il.com
Subject: [PATCH bpf-next] bpf: better availability probing for seg6 helpers
bpf_lwt_seg6_* helpers require CONFIG_IPV6_SEG6_BPF, and currently
return -EOPNOTSUPP to indicate unavailability. This patch forces the
BPF verifier to reject programs using these helpers when
!CONFIG_IPV6_SEG6_BPF, allowing users to more easily probe if they are
available or not.
Signed-off-by: Mathieu Xhonneux <m.xhonneux@...il.com>
---
net/core/filter.c | 22 ++++++++--------------
1 file changed, 8 insertions(+), 14 deletions(-)
diff --git a/net/core/filter.c b/net/core/filter.c
index b9ec916f4e3a..c910a95e9a7c 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -4439,10 +4439,10 @@ static const struct bpf_func_proto bpf_lwt_push_encap_proto = {
.arg4_type = ARG_CONST_SIZE
};
+#if IS_ENABLED(CONFIG_IPV6_SEG6_BPF)
BPF_CALL_4(bpf_lwt_seg6_store_bytes, struct sk_buff *, skb, u32, offset,
const void *, from, u32, len)
{
-#if IS_ENABLED(CONFIG_IPV6_SEG6_BPF)
struct seg6_bpf_srh_state *srh_state =
this_cpu_ptr(&seg6_bpf_srh_states);
void *srh_tlvs, *srh_end, *ptr;
@@ -4468,9 +4468,6 @@ BPF_CALL_4(bpf_lwt_seg6_store_bytes, struct sk_buff *, skb, u32, offset,
memcpy(skb->data + offset, from, len);
return 0;
-#else /* CONFIG_IPV6_SEG6_BPF */
- return -EOPNOTSUPP;
-#endif
}
static const struct bpf_func_proto bpf_lwt_seg6_store_bytes_proto = {
@@ -4486,7 +4483,6 @@ static const struct bpf_func_proto bpf_lwt_seg6_store_bytes_proto = {
BPF_CALL_4(bpf_lwt_seg6_action, struct sk_buff *, skb,
u32, action, void *, param, u32, param_len)
{
-#if IS_ENABLED(CONFIG_IPV6_SEG6_BPF)
struct seg6_bpf_srh_state *srh_state =
this_cpu_ptr(&seg6_bpf_srh_states);
struct ipv6_sr_hdr *srh;
@@ -4534,9 +4530,6 @@ BPF_CALL_4(bpf_lwt_seg6_action, struct sk_buff *, skb,
default:
return -EINVAL;
}
-#else /* CONFIG_IPV6_SEG6_BPF */
- return -EOPNOTSUPP;
-#endif
}
static const struct bpf_func_proto bpf_lwt_seg6_action_proto = {
@@ -4552,7 +4545,6 @@ static const struct bpf_func_proto bpf_lwt_seg6_action_proto = {
BPF_CALL_3(bpf_lwt_seg6_adjust_srh, struct sk_buff *, skb, u32, offset,
s32, len)
{
-#if IS_ENABLED(CONFIG_IPV6_SEG6_BPF)
struct seg6_bpf_srh_state *srh_state =
this_cpu_ptr(&seg6_bpf_srh_states);
void *srh_end, *srh_tlvs, *ptr;
@@ -4596,9 +4588,6 @@ BPF_CALL_3(bpf_lwt_seg6_adjust_srh, struct sk_buff *, skb, u32, offset,
srh_state->hdrlen += len;
srh_state->valid = 0;
return 0;
-#else /* CONFIG_IPV6_SEG6_BPF */
- return -EOPNOTSUPP;
-#endif
}
static const struct bpf_func_proto bpf_lwt_seg6_adjust_srh_proto = {
@@ -4609,6 +4598,7 @@ static const struct bpf_func_proto bpf_lwt_seg6_adjust_srh_proto = {
.arg2_type = ARG_ANYTHING,
.arg3_type = ARG_ANYTHING,
};
+#endif /* CONFIG_IPV6_SEG6_BPF */
bool bpf_helper_changes_pkt_data(void *func)
{
@@ -4627,10 +4617,12 @@ bool bpf_helper_changes_pkt_data(void *func)
func == bpf_xdp_adjust_meta ||
func == bpf_msg_pull_data ||
func == bpf_xdp_adjust_tail ||
- func == bpf_lwt_push_encap ||
+#if IS_ENABLED(CONFIG_IPV6_SEG6_BPF)
func == bpf_lwt_seg6_store_bytes ||
func == bpf_lwt_seg6_adjust_srh ||
- func == bpf_lwt_seg6_action
+ func == bpf_lwt_seg6_action ||
+#endif
+ func == bpf_lwt_push_encap
)
return true;
@@ -4967,12 +4959,14 @@ static const struct bpf_func_proto *
lwt_seg6local_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
switch (func_id) {
+#if IS_ENABLED(CONFIG_IPV6_SEG6_BPF)
case BPF_FUNC_lwt_seg6_store_bytes:
return &bpf_lwt_seg6_store_bytes_proto;
case BPF_FUNC_lwt_seg6_action:
return &bpf_lwt_seg6_action_proto;
case BPF_FUNC_lwt_seg6_adjust_srh:
return &bpf_lwt_seg6_adjust_srh_proto;
+#endif
default:
return lwt_out_func_proto(func_id, prog);
}
--
2.16.1
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