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Chenbo Fengdavem330
Chenbo Feng
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davem330
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A Sample of using socket cookie and uid for traffic monitoring
Add a sample program to demostrate the possible usage of get_socket_cookie and get_socket_uid helper function. The program will store bytes and packets counting of in/out traffic monitored by iptables and store the stats in a bpf map in per socket base. The owner uid of the socket will be stored as part of the data entry. A shell script for running the program is also included. Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Willem de Bruijn <willemb@google.com> Signed-off-by: Chenbo Feng <fengc@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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‎samples/bpf/Makefile

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@@ -35,6 +35,7 @@ hostprogs-y += tc_l2_redirect
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hostprogs-y += lwt_len_hist
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hostprogs-y += xdp_tx_iptunnel
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hostprogs-y += test_map_in_map
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hostprogs-y += per_socket_stats_example
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# Libbpf dependencies
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LIBBPF := ../../tools/lib/bpf/bpf.o
@@ -74,6 +75,7 @@ tc_l2_redirect-objs := bpf_load.o $(LIBBPF) tc_l2_redirect_user.o
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lwt_len_hist-objs := bpf_load.o $(LIBBPF) lwt_len_hist_user.o
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xdp_tx_iptunnel-objs := bpf_load.o $(LIBBPF) xdp_tx_iptunnel_user.o
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test_map_in_map-objs := bpf_load.o $(LIBBPF) test_map_in_map_user.o
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per_socket_stats_example-objs := $(LIBBPF) cookie_uid_helper_example.o
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# Tell kbuild to always build the programs
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always := $(hostprogs-y)
@@ -108,6 +110,7 @@ always += sampleip_kern.o
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always += lwt_len_hist_kern.o
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always += xdp_tx_iptunnel_kern.o
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always += test_map_in_map_kern.o
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always += cookie_uid_helper_example.o
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HOSTCFLAGS += -I$(objtree)/usr/include
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HOSTCFLAGS += -I$(srctree)/tools/lib/

‎samples/bpf/cookie_uid_helper_example.c

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/* This test is a demo of using get_socket_uid and get_socket_cookie
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* helper function to do per socket based network traffic monitoring.
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* It requires iptables version higher then 1.6.1. to load pinned eBPF
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* program into the xt_bpf match.
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*
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* TEST:
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* ./run_cookie_uid_helper_example.sh
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* Then generate some traffic in variate ways. ping 0 -c 10 would work
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* but the cookie and uid in this case could both be 0. A sample output
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* with some traffic generated by web browser is shown below:
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*
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* cookie: 877, uid: 0x3e8, Pakcet Count: 20, Bytes Count: 11058
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* cookie: 132, uid: 0x0, Pakcet Count: 2, Bytes Count: 286
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* cookie: 812, uid: 0x3e8, Pakcet Count: 3, Bytes Count: 1726
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* cookie: 802, uid: 0x3e8, Pakcet Count: 2, Bytes Count: 104
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* cookie: 877, uid: 0x3e8, Pakcet Count: 20, Bytes Count: 11058
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* cookie: 831, uid: 0x3e8, Pakcet Count: 2, Bytes Count: 104
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* cookie: 0, uid: 0x0, Pakcet Count: 6, Bytes Count: 712
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* cookie: 880, uid: 0xfffe, Pakcet Count: 1, Bytes Count: 70
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*
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* Clean up: if using shell script, the script file will delete the iptables
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* rule and unmount the bpf program when exit. Else the iptables rule need
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* to be deleted by hand, see run_cookie_uid_helper_example.sh for detail.
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*/
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#define _GNU_SOURCE
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#define offsetof(type, member) __builtin_offsetof(type, member)
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#define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))
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#include <arpa/inet.h>
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#include <errno.h>
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#include <error.h>
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#include <limits.h>
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#include <linux/bpf.h>
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#include <linux/if_ether.h>
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#include <stdbool.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/socket.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include <bpf/bpf.h>
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#include "libbpf.h"
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struct stats {
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uint32_t uid;
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uint64_t packets;
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uint64_t bytes;
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};
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static int map_fd, prog_fd;
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static void maps_create(void)
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{
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map_fd = bpf_create_map(BPF_MAP_TYPE_HASH, sizeof(uint32_t),
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sizeof(struct stats), 100, 0);
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if (map_fd < 0)
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error(1, errno, "map create failed!\n");
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}
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static void prog_load(void)
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{
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static char log_buf[1 << 16];
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struct bpf_insn prog[] = {
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/*
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* Save sk_buff for future usage. value stored in R6 to R10 will
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* not be reset after a bpf helper function call.
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*/
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BPF_MOV64_REG(BPF_REG_6, BPF_REG_1),
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/*
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* pc1: BPF_FUNC_get_socket_cookie takes one parameter,
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* R1: sk_buff
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*/
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BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
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BPF_FUNC_get_socket_cookie),
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/* pc2-4: save &socketCookie to r7 for future usage*/
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BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_0, -8),
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BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
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BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
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/*
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* pc5-8: set up the registers for BPF_FUNC_map_lookup_elem,
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* it takes two parameters (R1: map_fd, R2: &socket_cookie)
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*/
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BPF_LD_MAP_FD(BPF_REG_1, map_fd),
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BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
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BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
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BPF_FUNC_map_lookup_elem),
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/*
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* pc9. if r0 != 0x0, go to pc+14, since we have the cookie
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* stored already
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* Otherwise do pc10-22 to setup a new data entry.
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*/
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BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 14),
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BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
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BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
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BPF_FUNC_get_socket_uid),
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/*
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* Place a struct stats in the R10 stack and sequentially
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* place the member value into the memory. Packets value
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* is set by directly place a IMM value 1 into the stack.
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*/
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BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_0,
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-32 + offsetof(struct stats, uid)),
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BPF_ST_MEM(BPF_DW, BPF_REG_10,
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-32 + offsetof(struct stats, packets), 1),
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/*
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* __sk_buff is a special struct used for eBPF program to
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* directly access some sk_buff field.
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*/
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BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_6,
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offsetof(struct __sk_buff, len)),
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BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_1,
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-32 + offsetof(struct stats, bytes)),
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/*
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* add new map entry using BPF_FUNC_map_update_elem, it takes
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* 4 parameters (R1: map_fd, R2: &socket_cookie, R3: &stats,
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* R4: flags)
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*/
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BPF_LD_MAP_FD(BPF_REG_1, map_fd),
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BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
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BPF_MOV64_REG(BPF_REG_3, BPF_REG_10),
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BPF_ALU64_IMM(BPF_ADD, BPF_REG_3, -32),
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BPF_MOV64_IMM(BPF_REG_4, 0),
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BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
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BPF_FUNC_map_update_elem),
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BPF_JMP_IMM(BPF_JA, 0, 0, 5),
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/*
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* pc24-30 update the packet info to a exist data entry, it can
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* be done by directly write to pointers instead of using
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* BPF_FUNC_map_update_elem helper function
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*/
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BPF_MOV64_REG(BPF_REG_9, BPF_REG_0),
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BPF_MOV64_IMM(BPF_REG_1, 1),
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BPF_STX_XADD(BPF_DW, BPF_REG_9, BPF_REG_1,
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offsetof(struct stats, packets)),
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BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_6,
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offsetof(struct __sk_buff, len)),
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BPF_STX_XADD(BPF_DW, BPF_REG_9, BPF_REG_1,
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offsetof(struct stats, bytes)),
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BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_6,
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offsetof(struct __sk_buff, len)),
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BPF_EXIT_INSN(),
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};
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prog_fd = bpf_load_program(BPF_PROG_TYPE_SOCKET_FILTER, prog,
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ARRAY_SIZE(prog), "GPL", 0,
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log_buf, sizeof(log_buf));
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if (prog_fd < 0)
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error(1, errno, "failed to load prog\n%s\n", log_buf);
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}
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static void prog_attach_iptables(char *file)
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{
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int ret;
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char rules[100];
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if (bpf_obj_pin(prog_fd, file))
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error(1, errno, "bpf_obj_pin");
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if (strlen(file) > 50) {
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printf("file path too long: %s\n", file);
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exit(1);
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}
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sprintf(rules, "iptables -A INPUT -m bpf --object-pinned %s -j ACCEPT",
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file);
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ret = system(rules);
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if (ret < 0) {
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printf("iptables rule update failed: %d/n", WEXITSTATUS(ret));
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exit(1);
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}
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}
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static void print_table(void)
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{
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struct stats curEntry;
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uint32_t curN = UINT32_MAX;
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uint32_t nextN, res;
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while (bpf_map_get_next_key(map_fd, &curN, &nextN) > -1) {
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curN = nextN;
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res = bpf_map_lookup_elem(map_fd, &curN, &curEntry);
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if (res < 0) {
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error(1, errno, "fail to get entry value of Key: %u\n",
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curN);
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} else {
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printf("cookie: %u, uid: 0x%x, Packet Count: %lu,"
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" Bytes Count: %lu\n", curN, curEntry.uid,
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curEntry.packets, curEntry.bytes);
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}
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}
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}
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int main(int argc, char *argv[])
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{
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if (argc > 2) {
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printf("Too many argument provided\n");
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return 1;
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} else if (argc < 2) {
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printf("Usage: %s bpfObjName\n", argv[0]);
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return 1;
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}
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maps_create();
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prog_load();
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prog_attach_iptables(argv[1]);
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while (true) {
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print_table();
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printf("\n");
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sleep(1);
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};
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return 0;
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}

‎samples/bpf/libbpf.h

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@@ -135,6 +135,16 @@ struct bpf_insn;
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.off = OFF, \
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.imm = 0 })
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/* Atomic memory add, *(uint *)(dst_reg + off16) += src_reg */
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#define BPF_STX_XADD(SIZE, DST, SRC, OFF) \
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((struct bpf_insn) { \
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.code = BPF_STX | BPF_SIZE(SIZE) | BPF_XADD, \
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.dst_reg = DST, \
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.src_reg = SRC, \
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.off = OFF, \
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.imm = 0 })
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138148
/* Memory store, *(uint *) (dst_reg + off16) = imm32 */
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#define BPF_ST_MEM(SIZE, DST, OFF, IMM) \

‎samples/bpf/run_cookie_uid_helper_example.sh

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#!/bin/bash
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local_dir="$(pwd)"
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root_dir=$local_dir/../..
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mnt_dir=$(mktemp -d --tmp)
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on_exit() {
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iptables -D INPUT -m bpf --object-pinned ${mnt_dir}/bpf_prog -j ACCEPT
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umount ${mnt_dir}
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rm -r ${mnt_dir}
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}
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trap on_exit EXIT
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mount -t bpf bpf ${mnt_dir}
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./per_socket_stats_example ${mnt_dir}/bpf_prog

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