96a8eb1eee
Some of the sample files are causing issues when they are loaded with tc and cls_bpf, meaning tc bails out while trying to parse the resulting ELF file as program/map/etc sections are not present, which can be easily spotted with readelf(1). Currently, BPF samples are including some of the kernel headers and mid term we should change them to refrain from this, really. When dynamic debugging is enabled, we bail out due to undeclared KBUILD_MODNAME, which is easily overlooked in the build as clang spills this along with other noisy warnings from various header includes, and llc still generates an ELF file with mentioned characteristics. For just playing around with BPF examples, this can be a bit of a hurdle to take. Just add a fake KBUILD_MODNAME as a band-aid to fix the issue, same is done in xdp*_kern samples already. Fixes:65d472fb00("samples/bpf: add 'pointer to packet' tests") Fixes:6afb1e28b8("samples/bpf: Add tunnel set/get tests.") Fixes:a3f7461734("cgroup: bpf: Add an example to do cgroup checking in BPF") Reported-by: Chandrasekar Kannan <ckannan@console.to> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
90 lines
2.5 KiB
C
90 lines
2.5 KiB
C
#define KBUILD_MODNAME "foo"
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#include <uapi/linux/bpf.h>
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#include <uapi/linux/if_ether.h>
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#include <uapi/linux/if_packet.h>
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#include <uapi/linux/ip.h>
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#include <uapi/linux/in.h>
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#include <uapi/linux/tcp.h>
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#include <uapi/linux/filter.h>
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#include <uapi/linux/pkt_cls.h>
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#include "bpf_helpers.h"
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/* compiler workaround */
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#define _htonl __builtin_bswap32
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static inline void set_dst_mac(struct __sk_buff *skb, char *mac)
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{
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bpf_skb_store_bytes(skb, 0, mac, ETH_ALEN, 1);
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}
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#define IP_CSUM_OFF (ETH_HLEN + offsetof(struct iphdr, check))
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#define TOS_OFF (ETH_HLEN + offsetof(struct iphdr, tos))
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static inline void set_ip_tos(struct __sk_buff *skb, __u8 new_tos)
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{
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__u8 old_tos = load_byte(skb, TOS_OFF);
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bpf_l3_csum_replace(skb, IP_CSUM_OFF, htons(old_tos), htons(new_tos), 2);
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bpf_skb_store_bytes(skb, TOS_OFF, &new_tos, sizeof(new_tos), 0);
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}
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#define TCP_CSUM_OFF (ETH_HLEN + sizeof(struct iphdr) + offsetof(struct tcphdr, check))
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#define IP_SRC_OFF (ETH_HLEN + offsetof(struct iphdr, saddr))
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#define IS_PSEUDO 0x10
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static inline void set_tcp_ip_src(struct __sk_buff *skb, __u32 new_ip)
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{
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__u32 old_ip = _htonl(load_word(skb, IP_SRC_OFF));
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bpf_l4_csum_replace(skb, TCP_CSUM_OFF, old_ip, new_ip, IS_PSEUDO | sizeof(new_ip));
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bpf_l3_csum_replace(skb, IP_CSUM_OFF, old_ip, new_ip, sizeof(new_ip));
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bpf_skb_store_bytes(skb, IP_SRC_OFF, &new_ip, sizeof(new_ip), 0);
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}
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#define TCP_DPORT_OFF (ETH_HLEN + sizeof(struct iphdr) + offsetof(struct tcphdr, dest))
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static inline void set_tcp_dest_port(struct __sk_buff *skb, __u16 new_port)
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{
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__u16 old_port = htons(load_half(skb, TCP_DPORT_OFF));
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bpf_l4_csum_replace(skb, TCP_CSUM_OFF, old_port, new_port, sizeof(new_port));
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bpf_skb_store_bytes(skb, TCP_DPORT_OFF, &new_port, sizeof(new_port), 0);
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}
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SEC("classifier")
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int bpf_prog1(struct __sk_buff *skb)
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{
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__u8 proto = load_byte(skb, ETH_HLEN + offsetof(struct iphdr, protocol));
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long *value;
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if (proto == IPPROTO_TCP) {
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set_ip_tos(skb, 8);
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set_tcp_ip_src(skb, 0xA010101);
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set_tcp_dest_port(skb, 5001);
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}
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return 0;
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}
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SEC("redirect_xmit")
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int _redirect_xmit(struct __sk_buff *skb)
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{
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return bpf_redirect(skb->ifindex + 1, 0);
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}
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SEC("redirect_recv")
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int _redirect_recv(struct __sk_buff *skb)
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{
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return bpf_redirect(skb->ifindex + 1, 1);
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}
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SEC("clone_redirect_xmit")
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int _clone_redirect_xmit(struct __sk_buff *skb)
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{
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bpf_clone_redirect(skb, skb->ifindex + 1, 0);
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return TC_ACT_SHOT;
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}
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SEC("clone_redirect_recv")
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int _clone_redirect_recv(struct __sk_buff *skb)
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{
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bpf_clone_redirect(skb, skb->ifindex + 1, 1);
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return TC_ACT_SHOT;
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}
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char _license[] SEC("license") = "GPL";
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