[PATCH v9 bpf-next 09/14] bpf: introduce bpf_xdp_get_buff_len helper

Lorenzo Bianconi
2021-06-14T12:51:29Z

Introduce bpf_xdp_get_buff_len helper in order to return the xdp buffer
total size (linear and paged area)

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
include/uapi/linux/bpf.h | 7 +++++++
net/core/filter.c | 23 +++++++++++++++++++++++
tools/include/uapi/linux/bpf.h | 7 +++++++
3 files changed, 37 insertions(+)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 2c1ba70abbf1..0116c0c569fe 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -4778,6 +4778,12 @@ union bpf_attr {
* Execute close syscall for given FD.
* Return
* A syscall result.
+ *
+ * int bpf_xdp_get_buff_len(struct xdp_buff *xdp_md)
+ * Description
+ * Get the total size of a given xdp buff (linear and paged area)
+ * Return
+ * The total size of a given xdp buffer.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -4949,6 +4955,7 @@ union bpf_attr {
FN(sys_bpf), \
FN(btf_find_by_name_kind), \
FN(sys_close), \
+ FN(xdp_get_buff_len), \
/* */

/* 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 05f574a3d690..b0855f2d4726 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3918,6 +3918,27 @@ static int bpf_xdp_mb_adjust_tail(struct xdp_buff *xdp, int offset)
return 0;
}

+BPF_CALL_1(bpf_xdp_get_buff_len, struct xdp_buff*, xdp)
+{
+ int data_len = 0;
+
+ if (unlikely(xdp_buff_is_mb(xdp))) {
+ struct skb_shared_info *sinfo;
+
+ sinfo = xdp_get_shared_info_from_buff(xdp);
+ data_len = sinfo->data_len;
+ }
+
+ return (xdp->data_end - xdp->data) + data_len;
+}
+
+const struct bpf_func_proto bpf_xdp_get_buff_len_proto = {
+ .func = bpf_xdp_get_buff_len,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_CTX,
+};
+
BPF_CALL_2(bpf_xdp_adjust_tail, struct xdp_buff *, xdp, int, offset)
{
void *data_hard_end = xdp_data_hard_end(xdp); /* use xdp->frame_sz */
@@ -7454,6 +7475,8 @@ xdp_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return &bpf_xdp_redirect_map_proto;
case BPF_FUNC_xdp_adjust_tail:
return &bpf_xdp_adjust_tail_proto;
+ case BPF_FUNC_xdp_get_buff_len:
+ return &bpf_xdp_get_buff_len_proto;
case BPF_FUNC_fib_lookup:
return &bpf_xdp_fib_lookup_proto;
case BPF_FUNC_check_mtu:
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 2c1ba70abbf1..0116c0c569fe 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -4778,6 +4778,12 @@ union bpf_attr {
* Execute close syscall for given FD.
* Return
* A syscall result.
+ *
+ * int bpf_xdp_get_buff_len(struct xdp_buff *xdp_md)
+ * Description
+ * Get the total size of a given xdp buff (linear and paged area)
+ * Return
+ * The total size of a given xdp buffer.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -4949,6 +4955,7 @@ union bpf_attr {
FN(sys_bpf), \
FN(btf_find_by_name_kind), \
FN(sys_close), \
+ FN(xdp_get_buff_len), \
/* */

/* integer value in 'imm' field of BPF_CALL instruction selects which helper
--
2.31.1