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ktrace-CO-RE: Find running kernels BTF_ID for struct sk_buff

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Using bpf_core_type_id_kernel to find kernels BTF_ID for SKB.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
This commit is contained in:
Jesper Dangaard Brouer
2021-06-24 14:33:52 +02:00
parent e0298638bd
commit 2390b4b110
1 changed files with 5 additions and 1 deletions
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6
ktrace-CO-RE/ktrace01_kern.c
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@@ -50,12 +50,16 @@ int BPF_KPROBE(udp_send_skb, struct sk_buff___local *skb)
//int udp_send_skb(struct pt_regs *ctx) //int udp_send_skb(struct pt_regs *ctx)
{ {
unsigned int len; unsigned int len;
__u32 id;
__u32 h; __u32 h;
/* Find the kernels BTF_ID for struct sk_buff */
id = bpf_core_type_id_kernel(struct sk_buff___local);
BPF_CORE_READ_INTO(&h, skb, hash); /* skb->hash */ BPF_CORE_READ_INTO(&h, skb, hash); /* skb->hash */
BPF_CORE_READ_INTO(&len, skb, len); /* skb->len */ BPF_CORE_READ_INTO(&len, skb, len); /* skb->len */
bpf_printk("skb->hash=0x%x len=%d", h, len); bpf_printk("skb->hash=0x%x len=%d btf_id(skb)=%d", h, len, id);
return 0; return 0;
} }