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>

4 files changed, 244 insertions, 0 deletions

diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index 91c1d616d975..d42b495b0992 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -35,6 +35,7 @@ hostprogs-y += tc_l2_redirect
 hostprogs-y += lwt_len_hist
 hostprogs-y += xdp_tx_iptunnel
 hostprogs-y += test_map_in_map
+hostprogs-y += per_socket_stats_example
 
 # Libbpf dependencies
 LIBBPF := ../../tools/lib/bpf/bpf.o
@@ -74,6 +75,7 @@ tc_l2_redirect-objs := bpf_load.o $(LIBBPF) tc_l2_redirect_user.o
 lwt_len_hist-objs := bpf_load.o $(LIBBPF) lwt_len_hist_user.o
 xdp_tx_iptunnel-objs := bpf_load.o $(LIBBPF) xdp_tx_iptunnel_user.o
 test_map_in_map-objs := bpf_load.o $(LIBBPF) test_map_in_map_user.o
+per_socket_stats_example-objs := $(LIBBPF) cookie_uid_helper_example.o
 
 # Tell kbuild to always build the programs
 always := $(hostprogs-y)
@@ -108,6 +110,7 @@ always += sampleip_kern.o
 always += lwt_len_hist_kern.o
 always += xdp_tx_iptunnel_kern.o
 always += test_map_in_map_kern.o
+always += cookie_uid_helper_example.o
 
 HOSTCFLAGS += -I$(objtree)/usr/include
 HOSTCFLAGS += -I$(srctree)/tools/lib/
diff --git a/samples/bpf/cookie_uid_helper_example.c b/samples/bpf/cookie_uid_helper_example.c
new file mode 100644
index 000000000000..f6e5e58931c5
--- /dev/null
+++ b/samples/bpf/cookie_uid_helper_example.c
@@ -0,0 +1,217 @@
+/* This test is a demo of using get_socket_uid and get_socket_cookie
+ * helper function to do per socket based network traffic monitoring.
+ * It requires iptables version higher then 1.6.1. to load pinned eBPF
+ * program into the xt_bpf match.
+ *
+ * TEST:
+ * ./run_cookie_uid_helper_example.sh
+ * Then generate some traffic in variate ways. ping 0 -c 10 would work
+ * but the cookie and uid in this case could both be 0. A sample output
+ * with some traffic generated by web browser is shown below:
+ *
+ * cookie: 877, uid: 0x3e8, Pakcet Count: 20, Bytes Count: 11058
+ * cookie: 132, uid: 0x0, Pakcet Count: 2, Bytes Count: 286
+ * cookie: 812, uid: 0x3e8, Pakcet Count: 3, Bytes Count: 1726
+ * cookie: 802, uid: 0x3e8, Pakcet Count: 2, Bytes Count: 104
+ * cookie: 877, uid: 0x3e8, Pakcet Count: 20, Bytes Count: 11058
+ * cookie: 831, uid: 0x3e8, Pakcet Count: 2, Bytes Count: 104
+ * cookie: 0, uid: 0x0, Pakcet Count: 6, Bytes Count: 712
+ * cookie: 880, uid: 0xfffe, Pakcet Count: 1, Bytes Count: 70
+ *
+ * Clean up: if using shell script, the script file will delete the iptables
+ * rule and unmount the bpf program when exit. Else the iptables rule need
+ * to be deleted by hand, see run_cookie_uid_helper_example.sh for detail.
+ */
+
+#define _GNU_SOURCE
+
+#define offsetof(type, member)  __builtin_offsetof(type, member)
+#define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))
+
+#include <arpa/inet.h>
+#include <errno.h>
+#include <error.h>
+#include <limits.h>
+#include <linux/bpf.h>
+#include <linux/if_ether.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <bpf/bpf.h>
+#include "libbpf.h"
+
+struct stats {
+        uint32_t uid;
+        uint64_t packets;
+        uint64_t bytes;
+};
+
+static int map_fd, prog_fd;
+
+static void maps_create(void)
+{
+        map_fd = bpf_create_map(BPF_MAP_TYPE_HASH, sizeof(uint32_t),
+                                sizeof(struct stats), 100, 0);
+        if (map_fd < 0)
+                error(1, errno, "map create failed!\n");
+}
+
+static void prog_load(void)
+{
+        static char log_buf[1 << 16];
+
+        struct bpf_insn prog[] = {
+                /*
+                 * Save sk_buff for future usage. value stored in R6 to R10 will
+                 * not be reset after a bpf helper function call.
+                 */
+                BPF_MOV64_REG(BPF_REG_6, BPF_REG_1),
+                /*
+                 * pc1: BPF_FUNC_get_socket_cookie takes one parameter,
+                 * R1: sk_buff
+                 */
+                BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
+                                BPF_FUNC_get_socket_cookie),
+                /* pc2-4: save &socketCookie to r7 for future usage*/
+                BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_0, -8),
+                BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
+                BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
+                /*
+                 * pc5-8: set up the registers for BPF_FUNC_map_lookup_elem,
+                 * it takes two parameters (R1: map_fd,  R2: &socket_cookie)
+                 */
+                BPF_LD_MAP_FD(BPF_REG_1, map_fd),
+                BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
+                BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
+                                BPF_FUNC_map_lookup_elem),
+                /*
+                 * pc9. if r0 != 0x0, go to pc+14, since we have the cookie
+                 * stored already
+                 * Otherwise do pc10-22 to setup a new data entry.
+                 */
+                BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 14),
+                BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
+                BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
+                                BPF_FUNC_get_socket_uid),
+                /*
+                 * Place a struct stats in the R10 stack and sequentially
+                 * place the member value into the memory. Packets value
+                 * is set by directly place a IMM value 1 into the stack.
+                 */
+                BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_0,
+                                -32 + offsetof(struct stats, uid)),
+                BPF_ST_MEM(BPF_DW, BPF_REG_10,
+                                -32 + offsetof(struct stats, packets), 1),
+                /*
+                 * __sk_buff is a special struct used for eBPF program to
+                 * directly access some sk_buff field.
+                 */
+                BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_6,
+                                offsetof(struct __sk_buff, len)),
+                BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_1,
+                                -32 + offsetof(struct stats, bytes)),
+                /*
+                 * add new map entry using BPF_FUNC_map_update_elem, it takes
+                 * 4 parameters (R1: map_fd, R2: &socket_cookie, R3: &stats,
+                 * R4: flags)
+                 */
+                BPF_LD_MAP_FD(BPF_REG_1, map_fd),
+                BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
+                BPF_MOV64_REG(BPF_REG_3, BPF_REG_10),
+                BPF_ALU64_IMM(BPF_ADD, BPF_REG_3, -32),
+                BPF_MOV64_IMM(BPF_REG_4, 0),
+                BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
+                                BPF_FUNC_map_update_elem),
+                BPF_JMP_IMM(BPF_JA, 0, 0, 5),
+                /*
+                 * pc24-30 update the packet info to a exist data entry, it can
+                 * be done by directly write to pointers instead of using
+                 * BPF_FUNC_map_update_elem helper function
+                 */
+                BPF_MOV64_REG(BPF_REG_9, BPF_REG_0),
+                BPF_MOV64_IMM(BPF_REG_1, 1),
+                BPF_STX_XADD(BPF_DW, BPF_REG_9, BPF_REG_1,
+                                offsetof(struct stats, packets)),
+                BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_6,
+                                offsetof(struct __sk_buff, len)),
+                BPF_STX_XADD(BPF_DW, BPF_REG_9, BPF_REG_1,
+                                offsetof(struct stats, bytes)),
+                BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_6,
+                                offsetof(struct __sk_buff, len)),
+                BPF_EXIT_INSN(),
+        };
+        prog_fd = bpf_load_program(BPF_PROG_TYPE_SOCKET_FILTER, prog,
+                                        ARRAY_SIZE(prog), "GPL", 0,
+                                        log_buf, sizeof(log_buf));
+        if (prog_fd < 0)
+                error(1, errno, "failed to load prog\n%s\n", log_buf);
+}
+
+static void prog_attach_iptables(char *file)
+{
+        int ret;