diff options
Diffstat (limited to 'samples/bpf')
| -rw-r--r-- | samples/bpf/Makefile | 2 | ||||
| -rw-r--r-- | samples/bpf/libbpf.c | 28 | ||||
| -rw-r--r-- | samples/bpf/libbpf.h | 13 | ||||
| -rw-r--r-- | samples/bpf/sock_example.c | 101 |
4 files changed, 144 insertions, 0 deletions
diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile index 0718d9c..f46d349 100644 --- a/samples/bpf/Makefile +++ b/samples/bpf/Makefile @@ -3,9 +3,11 @@ obj- := dummy.o # List of programs to build hostprogs-y := test_verifier test_maps +hostprogs-y += sock_example test_verifier-objs := test_verifier.o libbpf.o test_maps-objs := test_maps.o libbpf.o +sock_example-objs := sock_example.o libbpf.o # Tell kbuild to always build the programs always := $(hostprogs-y) diff --git a/samples/bpf/libbpf.c b/samples/bpf/libbpf.c index 17bb520..46d50b7 100644 --- a/samples/bpf/libbpf.c +++ b/samples/bpf/libbpf.c @@ -7,6 +7,10 @@ #include <linux/netlink.h> #include <linux/bpf.h> #include <errno.h> +#include <net/ethernet.h> +#include <net/if.h> +#include <linux/if_packet.h> +#include <arpa/inet.h> #include "libbpf.h" static __u64 ptr_to_u64(void *ptr) @@ -93,3 +97,27 @@ int bpf_prog_load(enum bpf_prog_type prog_type, return syscall(__NR_bpf, BPF_PROG_LOAD, &attr, sizeof(attr)); } + +int open_raw_sock(const char *name) +{ + struct sockaddr_ll sll; + int sock; + + sock = socket(PF_PACKET, SOCK_RAW | SOCK_NONBLOCK | SOCK_CLOEXEC, htons(ETH_P_ALL)); + if (sock < 0) { + printf("cannot create raw socket\n"); + return -1; + } + + memset(&sll, 0, sizeof(sll)); + sll.sll_family = AF_PACKET; + sll.sll_ifindex = if_nametoindex(name); + sll.sll_protocol = htons(ETH_P_ALL); + if (bind(sock, (struct sockaddr *)&sll, sizeof(sll)) < 0) { + printf("bind to %s: %s\n", name, strerror(errno)); + close(sock); + return -1; + } + + return sock; +} diff --git a/samples/bpf/libbpf.h b/samples/bpf/libbpf.h index f8678e5..cc62ad4 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 diff --git a/samples/bpf/sock_example.c b/samples/bpf/sock_example.c new file mode 100644 index 0000000..c8ad040 --- /dev/null +++ b/samples/bpf/sock_example.c @@ -0,0 +1,101 @@ +/* eBPF example program: + * - creates arraymap in kernel with key 4 bytes and value 8 bytes + * + * - loads eBPF program: + * r0 = skb->data[ETH_HLEN + offsetof(struct iphdr, protocol)]; + * *(u32*)(fp - 4) = r0; + * // assuming packet is IPv4, lookup ip->proto in a map + * value = bpf_map_lookup_elem(map_fd, fp - 4); + * if (value) + * (*(u64*)value) += 1; + * + * - attaches this program to eth0 raw socket + * + * - every second user space reads map[tcp], map[udp], map[icmp] to see + * how many packets of given protocol were seen on eth0 + */ +#include <stdio.h> +#include <unistd.h> +#include <assert.h> +#include <linux/bpf.h> +#include <string.h> +#include <stdlib.h> +#include <errno.h> +#include <sys/socket.h> +#include <arpa/inet.h> +#include <linux/if_ether.h> +#include <linux/ip.h> +#include <stddef.h> +#include "libbpf.h" + +static int test_sock(void) +{ + int sock = -1, map_fd, prog_fd, i, key; + long long value = 0, tcp_cnt, udp_cnt, icmp_cnt; + + map_fd = bpf_create_map(BPF_MAP_TYPE_ARRAY, sizeof(key), sizeof(value), + 256); + if (map_fd < 0) { + printf("failed to create map '%s'\n", strerror(errno)); + goto cleanup; + } + + struct bpf_insn prog[] = { + BPF_MOV64_REG(BPF_REG_6, BPF_REG_1), + BPF_LD_ABS(BPF_B, ETH_HLEN + offsetof(struct iphdr, protocol) /* R0 = ip->proto */), + BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_0, -4), /* *(u32 *)(fp - 4) = r0 */ + BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), + BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), /* r2 = fp - 4 */ + BPF_LD_MAP_FD(BPF_REG_1, map_fd), + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem), + BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2), + BPF_MOV64_IMM(BPF_REG_1, 1), /* r1 = 1 */ + BPF_RAW_INSN(BPF_STX | BPF_XADD | BPF_DW, BPF_REG_0, BPF_REG_1, 0, 0), /* xadd r0 += r1 */ + BPF_MOV64_IMM(BPF_REG_0, 0), /* r0 = 0 */ + BPF_EXIT_INSN(), + }; + + prog_fd = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, prog, sizeof(prog), + "GPL"); + if (prog_fd < 0) { + printf("failed to load prog '%s'\n", strerror(errno)); + goto cleanup; + } + + sock = open_raw_sock("lo"); + + if (setsockopt(sock, SOL_SOCKET, SO_ATTACH_BPF, &prog_fd, + sizeof(prog_fd)) < 0) { + printf("setsockopt %s\n", strerror(errno)); + goto cleanup; + } + + for (i = 0; i < 10; i++) { + key = IPPROTO_TCP; + assert(bpf_lookup_elem(map_fd, &key, &tcp_cnt) == 0); + + key = IPPROTO_UDP; + assert(bpf_lookup_elem(map_fd, &key, &udp_cnt) == 0); + + key = IPPROTO_ICMP; + assert(bpf_lookup_elem(map_fd, &key, &icmp_cnt) == 0); + + printf("TCP %lld UDP %lld ICMP %lld packets\n", + tcp_cnt, udp_cnt, icmp_cnt); + sleep(1); + } + +cleanup: + /* maps, programs, raw sockets will auto cleanup on process exit */ + return 0; +} + +int main(void) +{ + FILE *f; + + f = popen("ping -c5 localhost", "r"); + (void)f; + + return test_sock(); +} |
