Existing 'bpf_skb_set_tunnel_opt' allows setting tunnel options given
an option buffer (ARG_PTR_TO_MEM|MEM_RDONLY) 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 imposssibly without knowing sender's exact geneve
options length, which unfortunately is dymamic.
Introduce 'skb_set_var_tunnel_opt'. This is a variant of
'bpf_skb_set_tunnel_opt' which gets an *additional* parameter 'len',
which is the byte length from 'opt' buffer to copy into ip_tunnnel_info.
The 'size' parameter is kept ARG_CONST_SIZE. This way, verifier can still
safe-guard buffer access. 'len' must never exceed 'size', o/w EINVAL is
returned.
Signed-off-by: Shmulik Ladkani <shmulik.ladkani@xxxxxxxxx>
---
include/uapi/linux/bpf.h | 12 ++++++++++++
net/core/filter.c | 34 +++++++++++++++++++++++++++++++---
tools/include/uapi/linux/bpf.h | 12 ++++++++++++
3 files changed, 55 insertions(+), 3 deletions(-)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 934a2a8beb87..1b965dfd0c80 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -5355,6 +5355,17 @@ union bpf_attr {
* Return
* Current *ktime*.
*
+ * long bpf_skb_set_var_tunnel_opt(struct sk_buff *skb, void *opt, u32 size, u32 len)
+ * Description
+ * Set tunnel options metadata for the packet associated to *skb*
+ * to the variable length *len* bytes of option data contained in
+ * the raw buffer *opt* sized *size*.
+ *
+ * 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), \
@@ -5566,6 +5577,7 @@ union bpf_attr {
FN(tcp_raw_check_syncookie_ipv4), \
FN(tcp_raw_check_syncookie_ipv6), \
FN(ktime_get_tai_ns), \
+ FN(skb_set_var_tunnel_opt), \
/* */
/* 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 1acfaffeaf32..894d780aff16 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -4669,8 +4669,8 @@ 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 inline u64 __bpf_skb_set_tunopt(struct sk_buff *skb,
+ const u8 *from, u32 size, u32 len)
{
struct ip_tunnel_info *info = skb_tunnel_info(skb);
const struct metadata_dst *md = this_cpu_ptr(md_dst);
@@ -4679,12 +4679,26 @@ BPF_CALL_3(bpf_skb_set_tunnel_opt, struct sk_buff *, skb,
return -EINVAL;
if (unlikely(size > IP_TUNNEL_OPTS_MAX))
return -ENOMEM;
+ if (unlikely(len > size))
+ return -EINVAL;
- ip_tunnel_info_opts_set(info, from, size, TUNNEL_OPTIONS_PRESENT);
+ ip_tunnel_info_opts_set(info, from, len, TUNNEL_OPTIONS_PRESENT);
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, size);
+}
+
+BPF_CALL_4(bpf_skb_set_var_tunnel_opt, struct sk_buff *, skb,
+ const u8 *, from, u32, size, u32, len)
+{
+ return __bpf_skb_set_tunopt(skb, from, size, len);
+}
+
static const struct bpf_func_proto bpf_skb_set_tunnel_opt_proto = {
.func = bpf_skb_set_tunnel_opt,
.gpl_only = false,
@@ -4694,6 +4708,16 @@ 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_var_tunnel_opt_proto = {
+ .func = bpf_skb_set_var_tunnel_opt,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_CTX,
+ .arg2_type = ARG_PTR_TO_MEM | MEM_RDONLY,
+ .arg3_type = ARG_CONST_SIZE,
+ .arg4_type = ARG_ANYTHING,
+};
+
static const struct bpf_func_proto *
bpf_get_skb_set_tunnel_proto(enum bpf_func_id which)
{
@@ -4714,6 +4738,8 @@ 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_var_tunnel_opt:
+ return &bpf_skb_set_var_tunnel_opt_proto;
default:
return NULL;
}
@@ -7826,6 +7852,7 @@ 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_var_tunnel_opt:
return bpf_get_skb_set_tunnel_proto(func_id);
case BPF_FUNC_redirect:
return &bpf_redirect_proto;
@@ -8169,6 +8196,7 @@ 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_var_tunnel_opt:
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 1d6085e15fc8..1a1083db5b7a 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -5355,6 +5355,17 @@ union bpf_attr {
* Return
* Current *ktime*.
*
+ * long bpf_skb_set_var_tunnel_opt(struct sk_buff *skb, void *opt, u32 size, u32 len)
+ * Description
+ * Set tunnel options metadata for the packet associated to *skb*
+ * to the variable length *len* bytes of option data contained in
+ * the raw buffer *opt* sized *size*.
+ *
+ * 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), \
@@ -5566,6 +5577,7 @@ union bpf_attr {
FN(tcp_raw_check_syncookie_ipv4), \
FN(tcp_raw_check_syncookie_ipv6), \
FN(ktime_get_tai_ns), \
+ FN(skb_set_var_tunnel_opt), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
--
2.37.2
