Existing 'bpf_skb_set_tunnel_opt' allows setting tunnel options given
an option buffer (ARG_PTR_TO_MEM) and the compile-time fixed buffer
size (ARG_CONST_SIZE).
However, in certain cases we wish to set tunnel options of dynamic
length.
For example, we have an ebpf program that gets geneve options on
incoming packets, stores them into a map (using a key representing
the incoming flow), and later needs to assign *same* options to
reply packets (belonging to same flow).
This is currently imposssible without knowing sender's exact geneve
options length, which unfortunately is dymamic.
Introduce 'bpf_skb_set_tunnel_opt_dynptr'.
This is a variant of 'bpf_skb_set_tunnel_opt' which gets a bpf dynamic
pointer (ARG_PTR_TO_DYNPTR) parameter whose data points to the options
buffer to set.
Signed-off-by: Shmulik Ladkani <shmulik.ladkani@xxxxxxxxx>
---
v3: Avoid 'inline' for the __bpf_skb_set_tunopt helper function
v4: change API to be based on bpf_dynptr, suggested by John Fastabend <john.fastabend@xxxxxxxxx>
v6: Remove superfluous 'len' from bpf_skb_set_tunnel_opt_dynptr API
(rely on dynptr's internal size), suggested by Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx>
---
include/uapi/linux/bpf.h | 11 +++++++++++
net/core/filter.c | 31 +++++++++++++++++++++++++++++--
tools/include/uapi/linux/bpf.h | 11 +++++++++++
3 files changed, 51 insertions(+), 2 deletions(-)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 3df78c56c1bf..ba12f7e1ccb6 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -5387,6 +5387,16 @@ union bpf_attr {
* Return
* Current *ktime*.
*
+ * long bpf_skb_set_tunnel_opt_dynptr(struct sk_buff *skb, struct bpf_dynptr *opt)
+ * Description
+ * Set tunnel options metadata for the packet associated to *skb*
+ * to the option data pointed to by the *opt* dynptr.
+ *
+ * See also the description of the **bpf_skb_get_tunnel_opt**\ ()
+ * helper for additional information.
+ * Return
+ * 0 on success, or a negative error in case of failure.
+ *
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -5598,6 +5608,7 @@ union bpf_attr {
FN(tcp_raw_check_syncookie_ipv4), \
FN(tcp_raw_check_syncookie_ipv6), \
FN(ktime_get_tai_ns), \
+ FN(skb_set_tunnel_opt_dynptr), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
diff --git a/net/core/filter.c b/net/core/filter.c
index e872f45399b0..1c652936ef86 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -4674,8 +4674,7 @@ static const struct bpf_func_proto bpf_skb_set_tunnel_key_proto = {
.arg4_type = ARG_ANYTHING,
};
-BPF_CALL_3(bpf_skb_set_tunnel_opt, struct sk_buff *, skb,
- const u8 *, from, u32, size)
+static u64 __bpf_skb_set_tunopt(struct sk_buff *skb, const u8 *from, u32 size)
{
struct ip_tunnel_info *info = skb_tunnel_info(skb);
const struct metadata_dst *md = this_cpu_ptr(md_dst);
@@ -4690,6 +4689,22 @@ BPF_CALL_3(bpf_skb_set_tunnel_opt, struct sk_buff *, skb,
return 0;
}
+BPF_CALL_3(bpf_skb_set_tunnel_opt, struct sk_buff *, skb,
+ const u8 *, from, u32, size)
+{
+ return __bpf_skb_set_tunopt(skb, from, size);
+}
+
+BPF_CALL_2(bpf_skb_set_tunnel_opt_dynptr, struct sk_buff *, skb,
+ struct bpf_dynptr_kern *, ptr)
+{
+ const u8 *from = bpf_dynptr_get_data(ptr);
+
+ if (unlikely(!from))
+ return -EFAULT;
+ return __bpf_skb_set_tunopt(skb, from, bpf_dynptr_get_size(ptr));
+}
+
static const struct bpf_func_proto bpf_skb_set_tunnel_opt_proto = {
.func = bpf_skb_set_tunnel_opt,
.gpl_only = false,
@@ -4699,6 +4714,14 @@ static const struct bpf_func_proto bpf_skb_set_tunnel_opt_proto = {
.arg3_type = ARG_CONST_SIZE,
};
+static const struct bpf_func_proto bpf_skb_set_tunnel_opt_dynptr_proto = {
+ .func = bpf_skb_set_tunnel_opt_dynptr,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_CTX,
+ .arg2_type = ARG_PTR_TO_DYNPTR | DYNPTR_TYPE_LOCAL,
+};
+
static const struct bpf_func_proto *
bpf_get_skb_set_tunnel_proto(enum bpf_func_id which)
{
@@ -4719,6 +4742,8 @@ bpf_get_skb_set_tunnel_proto(enum bpf_func_id which)
return &bpf_skb_set_tunnel_key_proto;
case BPF_FUNC_skb_set_tunnel_opt:
return &bpf_skb_set_tunnel_opt_proto;
+ case BPF_FUNC_skb_set_tunnel_opt_dynptr:
+ return &bpf_skb_set_tunnel_opt_dynptr_proto;
default:
return NULL;
}
@@ -7798,6 +7823,7 @@ tc_cls_act_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
case BPF_FUNC_skb_get_tunnel_opt:
return &bpf_skb_get_tunnel_opt_proto;
case BPF_FUNC_skb_set_tunnel_opt:
+ case BPF_FUNC_skb_set_tunnel_opt_dynptr:
return bpf_get_skb_set_tunnel_proto(func_id);
case BPF_FUNC_redirect:
return &bpf_redirect_proto;
@@ -8145,6 +8171,7 @@ lwt_xmit_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
case BPF_FUNC_skb_get_tunnel_opt:
return &bpf_skb_get_tunnel_opt_proto;
case BPF_FUNC_skb_set_tunnel_opt:
+ case BPF_FUNC_skb_set_tunnel_opt_dynptr:
return bpf_get_skb_set_tunnel_proto(func_id);
case BPF_FUNC_redirect:
return &bpf_redirect_proto;
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 3df78c56c1bf..ba12f7e1ccb6 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -5387,6 +5387,16 @@ union bpf_attr {
* Return
* Current *ktime*.
*
+ * long bpf_skb_set_tunnel_opt_dynptr(struct sk_buff *skb, struct bpf_dynptr *opt)
+ * Description
+ * Set tunnel options metadata for the packet associated to *skb*
+ * to the option data pointed to by the *opt* dynptr.
+ *
+ * See also the description of the **bpf_skb_get_tunnel_opt**\ ()
+ * helper for additional information.
+ * Return
+ * 0 on success, or a negative error in case of failure.
+ *
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -5598,6 +5608,7 @@ union bpf_attr {
FN(tcp_raw_check_syncookie_ipv4), \
FN(tcp_raw_check_syncookie_ipv6), \
FN(ktime_get_tai_ns), \
+ FN(skb_set_tunnel_opt_dynptr), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
--
2.37.3
