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linux/samples/bpf/sock_example.c

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samples: bpf: example of stateful socket filtering this socket filter example does: - creates arraymap in kernel with key 4 bytes and value 8 bytes - loads eBPF program which assumes that packet is IPv4 and loads one byte of IP->proto from the packet and uses it as a key in a map r0 = skb->data[ETH_HLEN + offsetof(struct iphdr, protocol)]; *(u32*)(fp - 4) = r0; value = bpf_map_lookup_elem(map_fd, fp - 4); if (value) (*(u64*)value) += 1; - attaches this program to raw socket - every second user space reads map[IPPROTO_TCP], map[IPPROTO_UDP], map[IPPROTO_ICMP] to see how many packets of given protocol were seen on loopback interface Usage: $sudo samples/bpf/sock_example TCP 0 UDP 0 ICMP 0 packets TCP 187600 UDP 0 ICMP 4 packets TCP 376504 UDP 0 ICMP 8 packets TCP 563116 UDP 0 ICMP 12 packets TCP 753144 UDP 0 ICMP 16 packets Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-12-01 15:06:36 -08:00
samples/bpf: add map_flags to bpf loader note old loader is compatible with new kernel. map_flags are optional Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-03-07 21:57:20 -08:00
samples: bpf: example of stateful socket filtering this socket filter example does: - creates arraymap in kernel with key 4 bytes and value 8 bytes - loads eBPF program which assumes that packet is IPv4 and loads one byte of IP->proto from the packet and uses it as a key in a map r0 = skb->data[ETH_HLEN + offsetof(struct iphdr, protocol)]; *(u32*)(fp - 4) = r0; value = bpf_map_lookup_elem(map_fd, fp - 4); if (value) (*(u64*)value) += 1; - attaches this program to raw socket - every second user space reads map[IPPROTO_TCP], map[IPPROTO_UDP], map[IPPROTO_ICMP] to see how many packets of given protocol were seen on loopback interface Usage: $sudo samples/bpf/sock_example TCP 0 UDP 0 ICMP 0 packets TCP 187600 UDP 0 ICMP 4 packets TCP 376504 UDP 0 ICMP 8 packets TCP 563116 UDP 0 ICMP 12 packets TCP 753144 UDP 0 ICMP 16 packets Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-12-01 15:06:36 -08:00
samples/bpf: Add simple non-portable kprobe filter example tracex1_kern.c - C program compiled into BPF. It attaches to kprobe:netif_receive_skb() When skb->dev->name == "lo", it prints sample debug message into trace_pipe via bpf_trace_printk() helper function. tracex1_user.c - corresponding user space component that: - loads BPF program via bpf() syscall - opens kprobes:netif_receive_skb event via perf_event_open() syscall - attaches the program to event via ioctl(event_fd, PERF_EVENT_IOC_SET_BPF, prog_fd); - prints from trace_pipe Note, this BPF program is non-portable. It must be recompiled with current kernel headers. kprobe is not a stable ABI and BPF+kprobe scripts may no longer be meaningful when kernel internals change. No matter in what way the kernel changes, neither the kprobe, nor the BPF program can ever crash or corrupt the kernel, assuming the kprobes, perf and BPF subsystem has no bugs. The verifier will detect that the program is using bpf_trace_printk() and the kernel will print 'this is a DEBUG kernel' warning banner, which means that bpf_trace_printk() should be used for debugging of the BPF program only. Usage: $ sudo tracex1 ping-19826 [000] d.s2 63103.382648: : skb ffff880466b1ca00 len 84 ping-19826 [000] d.s2 63103.382684: : skb ffff880466b1d300 len 84 ping-19826 [000] d.s2 63104.382533: : skb ffff880466b1ca00 len 84 ping-19826 [000] d.s2 63104.382594: : skb ffff880466b1d300 len 84 Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: David S. Miller <davem@davemloft.net> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/1427312966-8434-7-git-send-email-ast@plumgrid.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-03-25 12:49:23 -07:00
samples: bpf: example of stateful socket filtering this socket filter example does: - creates arraymap in kernel with key 4 bytes and value 8 bytes - loads eBPF program which assumes that packet is IPv4 and loads one byte of IP->proto from the packet and uses it as a key in a map r0 = skb->data[ETH_HLEN + offsetof(struct iphdr, protocol)]; *(u32*)(fp - 4) = r0; value = bpf_map_lookup_elem(map_fd, fp - 4); if (value) (*(u64*)value) += 1; - attaches this program to raw socket - every second user space reads map[IPPROTO_TCP], map[IPPROTO_UDP], map[IPPROTO_ICMP] to see how many packets of given protocol were seen on loopback interface Usage: $sudo samples/bpf/sock_example TCP 0 UDP 0 ICMP 0 packets TCP 187600 UDP 0 ICMP 4 packets TCP 376504 UDP 0 ICMP 8 packets TCP 563116 UDP 0 ICMP 12 packets TCP 753144 UDP 0 ICMP 16 packets Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-12-01 15:06:36 -08:00