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mitm-webserver/tools/ebpf/prepend_capture_header.c
malmert e73726fd1b
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ebpf fix 2
2026-03-07 15:44:48 +01:00

42 lines
931 B
C

#include <linux/bpf.h>
#include <linux/pkt_cls.h>
#include <bpf/bpf_endian.h>
#include <bpf/bpf_helpers.h>
#define CAPTURE_MAGIC 0x4d544350
#define CAPTURE_VERSION 1
struct capture_header {
__be32 magic;
__u8 version;
__u8 flags;
__be16 header_len;
__be32 skb_mark;
__be32 aux_value;
} __attribute__((packed));
SEC("classifier")
int prepend_capture_header_prog(struct __sk_buff *skb) {
struct capture_header hdr = {
.magic = bpf_htonl(CAPTURE_MAGIC),
.version = CAPTURE_VERSION,
.flags = 0,
.header_len = bpf_htons(sizeof(struct capture_header)),
.skb_mark = bpf_htonl(skb->mark),
.aux_value = 0,
};
if (!skb->mark) {
return TC_ACT_OK;
}
if (bpf_skb_adjust_room(skb, sizeof(hdr), BPF_ADJ_ROOM_MAC, 0)) {
return TC_ACT_OK;
}
if (bpf_skb_store_bytes(skb, 0, &hdr, sizeof(hdr), 0)) {
return TC_ACT_OK;
}
return TC_ACT_OK;
}
char LICENSE[] SEC("license") = "GPL";