* Return
* a non-negative value equal to or less than size on success, or
* a negative error in case of failure.
+ *
+ * int skb_load_bytes_relative(const struct sk_buff *skb, u32 offset, void *to, u32 len, u32 start_header)
+ * Description
+ * This helper is similar to **bpf_skb_load_bytes**\ () in that
+ * it provides an easy way to load *len* bytes from *offset*
+ * from the packet associated to *skb*, into the buffer pointed
+ * by *to*. The difference to **bpf_skb_load_bytes**\ () is that
+ * a fifth argument *start_header* exists in order to select a
+ * base offset to start from. *start_header* can be one of:
+ *
+ * **BPF_HDR_START_MAC**
+ * Base offset to load data from is *skb*'s mac header.
+ * **BPF_HDR_START_NET**
+ * Base offset to load data from is *skb*'s network header.
+ *
+ * In general, "direct packet access" is the preferred method to
+ * access packet data, however, this helper is in particular useful
+ * in socket filters where *skb*\ **->data** does not always point
+ * to the start of the mac header and where "direct packet access"
+ * is not available.
+ *
+ * Return
+ * 0 on success, or a negative error in case of failure.
+ *
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
FN(bind), \
FN(xdp_adjust_tail), \
FN(skb_get_xfrm_state), \
- FN(get_stack),
+ FN(get_stack), \
+ FN(skb_load_bytes_relative),
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
* function eBPF program intends to call
BPF_ADJ_ROOM_NET,
};
+/* Mode for BPF_FUNC_skb_load_bytes_relative helper. */
+enum bpf_hdr_start_off {
+ BPF_HDR_START_MAC,
+ BPF_HDR_START_NET,
+};
+
/* user accessible mirror of in-kernel sk_buff.
* new fields can only be added to the end of this structure
*/