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authorDaniel Borkmann <daniel@iogearbox.net>2016-04-18 22:01:24 +0300
committerDavid S. Miller <davem@davemloft.net>2016-04-20 03:26:11 +0300
commitbd570ff970a54df653b48ed0cfb373f2ebed083d (patch)
tree85e4ed3aa2bb859cf770247735eb9e7d9a909cb7 /include/linux/bpf.h
parent1e33759c788c78f31d4d6f65bac647b23624734c (diff)
downloadlinux-bd570ff970a54df653b48ed0cfb373f2ebed083d.tar.xz
bpf: add event output helper for notifications/sampling/logging
This patch adds a new helper for cls/act programs that can push events to user space applications. For networking, this can be f.e. for sampling, debugging, logging purposes or pushing of arbitrary wake-up events. The idea is similar to a43eec304259 ("bpf: introduce bpf_perf_event_output() helper") and 39111695b1b8 ("samples: bpf: add bpf_perf_event_output example"). The eBPF program utilizes a perf event array map that user space populates with fds from perf_event_open(), the eBPF program calls into the helper f.e. as skb_event_output(skb, &my_map, BPF_F_CURRENT_CPU, raw, sizeof(raw)) so that the raw data is pushed into the fd f.e. at the map index of the current CPU. User space can poll/mmap/etc on this and has a data channel for receiving events that can be post-processed. The nice thing is that since the eBPF program and user space application making use of it are tightly coupled, they can define their own arbitrary raw data format and what/when they want to push. While f.e. packet headers could be one part of the meta data that is being pushed, this is not a substitute for things like packet sockets as whole packet is not being pushed and push is only done in a single direction. Intention is more of a generically usable, efficient event pipe to applications. Workflow is that tc can pin the map and applications can attach themselves e.g. after cls/act setup to one or multiple map slots, demuxing is done by the eBPF program. Adding this facility is with minimal effort, it reuses the helper introduced in a43eec304259 ("bpf: introduce bpf_perf_event_output() helper") and we get its functionality for free by overloading its BPF_FUNC_ identifier for cls/act programs, ctx is currently unused, but will be made use of in future. Example will be added to iproute2's BPF example files. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/linux/bpf.h')
-rw-r--r--include/linux/bpf.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 5fb3c610fa96..f63afdc43bec 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -169,7 +169,9 @@ u64 bpf_tail_call(u64 ctx, u64 r2, u64 index, u64 r4, u64 r5);
u64 bpf_get_stackid(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
void bpf_fd_array_map_clear(struct bpf_map *map);
bool bpf_prog_array_compatible(struct bpf_array *array, const struct bpf_prog *fp);
+
const struct bpf_func_proto *bpf_get_trace_printk_proto(void);
+const struct bpf_func_proto *bpf_get_event_output_proto(void);
#ifdef CONFIG_BPF_SYSCALL
DECLARE_PER_CPU(int, bpf_prog_active);