Existing 'bpf_skb_get_tunnel_key' extracts various tunnel parameters
(id, ttl, tos, local and remote) but does not expose ip_tunnel_info's
tun_flags to the bpf program.
It makes sense to expose tun_flags to the bpf program.
Assume for example multiple GRE tunnels maintained on a single GRE
interface in collect_md mode. The program expects origins to initiate
over GRE, however different origins use different GRE characteristics
(e.g. some prefer to use GRE checksum, some do not; some pass a GRE key,
some do not, etc..).
A bpf program getting tun_flags can therefore remember the relevant
flags (e.g. TUNNEL_CSUM, TUNNEL_SEQ...) for each initiating remote.
In the reply path, the program can use 'bpf_skb_set_tunnel_key' in order
to correctly reply to the remote, using similar characteristics, based on
the stored tunnel flags.
Introduce BPF_F_TUNINFO_FLAGS flag for bpf_skb_get_tunnel_key.
If specified, 'bpf_tunnel_key->tunnel_flags' is set with the tun_flags.
Decided to use the existing unused 'tunnel_ext' as the storage for the
'tunnel_flags' in order to avoid changing bpf_tunnel_key's layout.
Signed-off-by: Shmulik Ladkani <shmulik.ladkani@xxxxxxxxx>
---
include/uapi/linux/bpf.h | 10 +++++++++-
net/core/filter.c | 8 ++++++--
tools/include/uapi/linux/bpf.h | 10 +++++++++-
3 files changed, 24 insertions(+), 4 deletions(-)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 962960a98835..837c0f9b7fdd 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -5659,6 +5659,11 @@ enum {
BPF_F_SEQ_NUMBER = (1ULL << 3),
};
+/* BPF_FUNC_skb_get_tunnel_key flags. */
+enum {
+ BPF_F_TUNINFO_FLAGS = (1ULL << 4),
+};
+
/* BPF_FUNC_perf_event_output, BPF_FUNC_perf_event_read and
* BPF_FUNC_perf_event_read_value flags.
*/
@@ -5848,7 +5853,10 @@ struct bpf_tunnel_key {
};
__u8 tunnel_tos;
__u8 tunnel_ttl;
- __u16 tunnel_ext; /* Padding, future use. */
+ union {
+ __u16 tunnel_ext; /* compat */
+ __be16 tunnel_flags;
+ };
__u32 tunnel_label;
union {
__u32 local_ipv4;
diff --git a/net/core/filter.c b/net/core/filter.c
index 63e25d8ce501..74e2a4a0d747 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -4488,7 +4488,8 @@ BPF_CALL_4(bpf_skb_get_tunnel_key, struct sk_buff *, skb, struct bpf_tunnel_key
void *to_orig = to;
int err;
- if (unlikely(!info || (flags & ~(BPF_F_TUNINFO_IPV6)))) {
+ if (unlikely(!info || (flags & ~(BPF_F_TUNINFO_IPV6 |
+ BPF_F_TUNINFO_FLAGS)))) {
err = -EINVAL;
goto err_clear;
}
@@ -4520,7 +4521,10 @@ BPF_CALL_4(bpf_skb_get_tunnel_key, struct sk_buff *, skb, struct bpf_tunnel_key
to->tunnel_id = be64_to_cpu(info->key.tun_id);
to->tunnel_tos = info->key.tos;
to->tunnel_ttl = info->key.ttl;
- to->tunnel_ext = 0;
+ if (flags & BPF_F_TUNINFO_FLAGS)
+ to->tunnel_flags = info->key.tun_flags;
+ else
+ to->tunnel_ext = 0;
if (flags & BPF_F_TUNINFO_IPV6) {
memcpy(to->remote_ipv6, &info->key.u.ipv6.src,
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index f4ba82a1eace..793103b10eab 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -5659,6 +5659,11 @@ enum {
BPF_F_SEQ_NUMBER = (1ULL << 3),
};
+/* BPF_FUNC_skb_get_tunnel_key flags. */
+enum {
+ BPF_F_TUNINFO_FLAGS = (1ULL << 4),
+};
+
/* BPF_FUNC_perf_event_output, BPF_FUNC_perf_event_read and
* BPF_FUNC_perf_event_read_value flags.
*/
@@ -5848,7 +5853,10 @@ struct bpf_tunnel_key {
};
__u8 tunnel_tos;
__u8 tunnel_ttl;
- __u16 tunnel_ext; /* Padding, future use. */
+ union {
+ __u16 tunnel_ext; /* compat */
+ __be16 tunnel_flags;
+ };
__u32 tunnel_label;
union {
__u32 local_ipv4;
--
2.37.2
