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authorAlexei Starovoitov <ast@plumgrid.com>2014-12-02 02:06:36 +0300
committerDavid S. Miller <davem@davemloft.net>2014-12-06 08:47:32 +0300
commit03f4723ed7a52bd31da26eefe2cdde563ea0f468 (patch)
tree4a3f1b2427c8bf1f2e86f4f1e842a32c5602b621 /samples/bpf/libbpf.h
parent89aa075832b0da4402acebd698d0411dcc82d03e (diff)
downloadlinux-03f4723ed7a52bd31da26eefe2cdde563ea0f468.tar.xz
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>
Diffstat (limited to 'samples/bpf/libbpf.h')
-rw-r--r--samples/bpf/libbpf.h13
1 files changed, 13 insertions, 0 deletions
diff --git a/samples/bpf/libbpf.h b/samples/bpf/libbpf.h
index f8678e5f48bf..cc62ad4d95de 100644
--- a/samples/bpf/libbpf.h
+++ b/samples/bpf/libbpf.h
@@ -99,6 +99,16 @@ extern char bpf_log_buf[LOG_BUF_SIZE];
BPF_LD_IMM64_RAW(DST, BPF_PSEUDO_MAP_FD, MAP_FD)
+/* Direct packet access, R0 = *(uint *) (skb->data + imm32) */
+
+#define BPF_LD_ABS(SIZE, IMM) \
+ ((struct bpf_insn) { \
+ .code = BPF_LD | BPF_SIZE(SIZE) | BPF_ABS, \
+ .dst_reg = 0, \
+ .src_reg = 0, \
+ .off = 0, \
+ .imm = IMM })
+
/* Memory load, dst_reg = *(uint *) (src_reg + off16) */
#define BPF_LDX_MEM(SIZE, DST, SRC, OFF) \
@@ -169,4 +179,7 @@ extern char bpf_log_buf[LOG_BUF_SIZE];
.off = 0, \
.imm = 0 })
+/* create RAW socket and bind to interface 'name' */
+int open_raw_sock(const char *name);
+
#endif