samples/bpf/cookie_uid_helper_example.c

0001 /* This test is a demo of using get_socket_uid and get_socket_cookie
0002  * helper function to do per socket based network traffic monitoring.
0003  * It requires iptables version higher then 1.6.1. to load pinned eBPF
0004  * program into the xt_bpf match.
0005  *
0006  * TEST:
0007  * ./run_cookie_uid_helper_example.sh -option
0008  * option:
0009  *  -t: do traffic monitoring test, the program will continuously
0010  * print out network traffic happens after program started A sample
0011  * output is shown below:
0012  *
0013  * cookie: 877, uid: 0x3e8, Pakcet Count: 20, Bytes Count: 11058
0014  * cookie: 132, uid: 0x0, Pakcet Count: 2, Bytes Count: 286
0015  * cookie: 812, uid: 0x3e8, Pakcet Count: 3, Bytes Count: 1726
0016  * cookie: 802, uid: 0x3e8, Pakcet Count: 2, Bytes Count: 104
0017  * cookie: 877, uid: 0x3e8, Pakcet Count: 20, Bytes Count: 11058
0018  * cookie: 831, uid: 0x3e8, Pakcet Count: 2, Bytes Count: 104
0019  * cookie: 0, uid: 0x0, Pakcet Count: 6, Bytes Count: 712
0020  * cookie: 880, uid: 0xfffe, Pakcet Count: 1, Bytes Count: 70
0021  *
0022  *  -s: do getsockopt SO_COOKIE test, the program will set up a pair of
0023  * UDP sockets and send packets between them. And read out the traffic data
0024  * directly from the ebpf map based on the socket cookie.
0025  *
0026  * Clean up: if using shell script, the script file will delete the iptables
0027  * rule and unmount the bpf program when exit. Else the iptables rule need
0028  * to be deleted by hand, see run_cookie_uid_helper_example.sh for detail.
0029  */
0030
0031 #define _GNU_SOURCE
0032
0033 #define offsetof(type, member)  __builtin_offsetof(type, member)
0034 #define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))
0035
0036 #include <arpa/inet.h>
0037 #include <errno.h>
0038 #include <error.h>
0039 #include <limits.h>
0040 #include <linux/bpf.h>
0041 #include <linux/if_ether.h>
0042 #include <net/if.h>
0043 #include <signal.h>
0044 #include <stdbool.h>
0045 #include <stdint.h>
0046 #include <stdio.h>
0047 #include <stdlib.h>
0048 #include <string.h>
0049 #include <sys/socket.h>
0050 #include <sys/stat.h>
0051 #include <sys/types.h>
0052 #include <unistd.h>
0053 #include <bpf/bpf.h>
0054 #include "bpf_insn.h"
0055
0056 #define PORT 8888
0057
0058 struct stats {
0059     uint32_t uid;
0060     uint64_t packets;
0061     uint64_t bytes;
0062 };
0063
0064 static int map_fd, prog_fd;
0065
0066 static bool test_finish;
0067
0068 static void maps_create(void)
0069 {
0070     map_fd = bpf_map_create(BPF_MAP_TYPE_HASH, NULL, sizeof(uint32_t),
0071                 sizeof(struct stats), 100, NULL);
0072     if (map_fd < 0)
0073         error(1, errno, "map create failed!\n");
0074 }
0075
0076 static void prog_load(void)
0077 {
0078     static char log_buf[1 << 16];
0079
0080     struct bpf_insn prog[] = {
0081         /*
0082          * Save sk_buff for future usage. value stored in R6 to R10 will
0083          * not be reset after a bpf helper function call.
0084          */
0085         BPF_MOV64_REG(BPF_REG_6, BPF_REG_1),
0086         /*
0087          * pc1: BPF_FUNC_get_socket_cookie takes one parameter,
0088          * R1: sk_buff
0089          */
0090         BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
0091                 BPF_FUNC_get_socket_cookie),
0092         /* pc2-4: save &socketCookie to r7 for future usage*/
0093         BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_0, -8),
0094         BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
0095         BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
0096         /*
0097          * pc5-8: set up the registers for BPF_FUNC_map_lookup_elem,
0098          * it takes two parameters (R1: map_fd,  R2: &socket_cookie)
0099          */
0100         BPF_LD_MAP_FD(BPF_REG_1, map_fd),
0101         BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
0102         BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
0103                 BPF_FUNC_map_lookup_elem),
0104         /*
0105          * pc9. if r0 != 0x0, go to pc+14, since we have the cookie
0106          * stored already
0107          * Otherwise do pc10-22 to setup a new data entry.
0108          */
0109         BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 14),
0110         BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
0111         BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
0112                 BPF_FUNC_get_socket_uid),
0113         /*
0114          * Place a struct stats in the R10 stack and sequentially
0115          * place the member value into the memory. Packets value
0116          * is set by directly place a IMM value 1 into the stack.
0117          */
0118         BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_0,
0119                 -32 + (__s16)offsetof(struct stats, uid)),
0120         BPF_ST_MEM(BPF_DW, BPF_REG_10,
0121                -32 + (__s16)offsetof(struct stats, packets), 1),
0122         /*
0123          * __sk_buff is a special struct used for eBPF program to
0124          * directly access some sk_buff field.
0125          */
0126         BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_6,
0127                 offsetof(struct __sk_buff, len)),
0128         BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_1,
0129                 -32 + (__s16)offsetof(struct stats, bytes)),
0130         /*
0131          * add new map entry using BPF_FUNC_map_update_elem, it takes
0132          * 4 parameters (R1: map_fd, R2: &socket_cookie, R3: &stats,
0133          * R4: flags)
0134          */
0135         BPF_LD_MAP_FD(BPF_REG_1, map_fd),
0136         BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
0137         BPF_MOV64_REG(BPF_REG_3, BPF_REG_10),
0138         BPF_ALU64_IMM(BPF_ADD, BPF_REG_3, -32),
0139         BPF_MOV64_IMM(BPF_REG_4, 0),
0140         BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
0141                 BPF_FUNC_map_update_elem),
0142         BPF_JMP_IMM(BPF_JA, 0, 0, 5),
0143         /*
0144          * pc24-30 update the packet info to a exist data entry, it can
0145          * be done by directly write to pointers instead of using
0146          * BPF_FUNC_map_update_elem helper function
0147          */
0148         BPF_MOV64_REG(BPF_REG_9, BPF_REG_0),
0149         BPF_MOV64_IMM(BPF_REG_1, 1),
0150         BPF_ATOMIC_OP(BPF_DW, BPF_ADD, BPF_REG_9, BPF_REG_1,
0151                   offsetof(struct stats, packets)),
0152         BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_6,
0153                 offsetof(struct __sk_buff, len)),
0154         BPF_ATOMIC_OP(BPF_DW, BPF_ADD, BPF_REG_9, BPF_REG_1,
0155                   offsetof(struct stats, bytes)),
0156         BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_6,
0157                 offsetof(struct __sk_buff, len)),
0158         BPF_EXIT_INSN(),
0159     };
0160     LIBBPF_OPTS(bpf_prog_load_opts, opts,
0161         .log_buf = log_buf,
0162         .log_size = sizeof(log_buf),
0163     );
0164
0165     prog_fd = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL",
0166                 prog, ARRAY_SIZE(prog), &opts);
0167     if (prog_fd < 0)
0168         error(1, errno, "failed to load prog\n%s\n", log_buf);
0169 }
0170
0171 static void prog_attach_iptables(char *file)
0172 {
0173     int ret;
0174     char rules[256];
0175
0176     if (bpf_obj_pin(prog_fd, file))
0177         error(1, errno, "bpf_obj_pin");
0178     if (strlen(file) > 50) {
0179         printf("file path too long: %s\n", file);
0180         exit(1);
0181     }
0182     ret = snprintf(rules, sizeof(rules),
0183                "iptables -A OUTPUT -m bpf --object-pinned %s -j ACCEPT",
0184                file);
0185     if (ret < 0 || ret >= sizeof(rules)) {
0186         printf("error constructing iptables command\n");
0187         exit(1);
0188     }
0189     ret = system(rules);
0190     if (ret < 0) {
0191         printf("iptables rule update failed: %d/n", WEXITSTATUS(ret));
0192         exit(1);
0193     }
0194 }
0195
0196 static void print_table(void)
0197 {
0198     struct stats curEntry;
0199     uint32_t curN = UINT32_MAX;
0200     uint32_t nextN;
0201     int res;
0202
0203     while (bpf_map_get_next_key(map_fd, &curN, &nextN) > -1) {
0204         curN = nextN;
0205         res = bpf_map_lookup_elem(map_fd, &curN, &curEntry);
0206         if (res < 0) {
0207             error(1, errno, "fail to get entry value of Key: %u\n",
0208                 curN);
0209         } else {
0210             printf("cookie: %u, uid: 0x%x, Packet Count: %lu,"
0211                 " Bytes Count: %lu\n", curN, curEntry.uid,
0212                 curEntry.packets, curEntry.bytes);
0213         }
0214     }
0215 }
0216
0217 static void udp_client(void)
0218 {
0219     struct sockaddr_in si_other = {0};
0220     struct sockaddr_in si_me = {0};
0221     struct stats dataEntry;
0222     int s_rcv, s_send, i, recv_len;
0223     char message = 'a';
0224     char buf;
0225     uint64_t cookie;
0226     int res;
0227     socklen_t cookie_len = sizeof(cookie);
0228     socklen_t slen = sizeof(si_other);
0229
0230     s_rcv = socket(PF_INET, SOCK_DGRAM, 0);
0231     if (s_rcv < 0)
0232         error(1, errno, "rcv socket creat failed!\n");
0233     si_other.sin_family = AF_INET;
0234     si_other.sin_port = htons(PORT);
0235     if (inet_aton("127.0.0.1", &si_other.sin_addr) == 0)
0236         error(1, errno, "inet_aton\n");
0237     if (bind(s_rcv, (struct sockaddr *)&si_other, sizeof(si_other)) == -1)
0238         error(1, errno, "bind\n");
0239     s_send = socket(PF_INET, SOCK_DGRAM, 0);
0240     if (s_send < 0)
0241         error(1, errno, "send socket creat failed!\n");
0242     res = getsockopt(s_send, SOL_SOCKET, SO_COOKIE, &cookie, &cookie_len);
0243     if (res < 0)
0244         printf("get cookie failed: %s\n", strerror(errno));
0245     res = bpf_map_lookup_elem(map_fd, &cookie, &dataEntry);
0246     if (res != -1)
0247         error(1, errno, "socket stat found while flow not active\n");
0248     for (i = 0; i < 10; i++) {
0249         res = sendto(s_send, &message, sizeof(message), 0,
0250                  (struct sockaddr *)&si_other, slen);
0251         if (res == -1)
0252             error(1, errno, "send\n");
0253         if (res != sizeof(message))
0254             error(1, 0, "%uB != %luB\n", res, sizeof(message));
0255         recv_len = recvfrom(s_rcv, &buf, sizeof(buf), 0,
0256                  (struct sockaddr *)&si_me, &slen);
0257         if (recv_len < 0)
0258             error(1, errno, "receive\n");
0259         res = memcmp(&(si_other.sin_addr), &(si_me.sin_addr),
0260                sizeof(si_me.sin_addr));
0261         if (res != 0)
0262             error(1, EFAULT, "sender addr error: %d\n", res);
0263         printf("Message received: %c\n", buf);
0264         res = bpf_map_lookup_elem(map_fd, &cookie, &dataEntry);
0265         if (res < 0)
0266             error(1, errno, "lookup sk stat failed, cookie: %lu\n",
0267                   cookie);
0268         printf("cookie: %lu, uid: 0x%x, Packet Count: %lu,"
0269             " Bytes Count: %lu\n\n", cookie, dataEntry.uid,
0270             dataEntry.packets, dataEntry.bytes);
0271     }
0272     close(s_send);
0273     close(s_rcv);
0274 }
0275
0276 static int usage(void)
0277 {
0278     printf("Usage: ./run_cookie_uid_helper_example.sh"
0279         " bpfObjName -option\n"
0280         "   -t  traffic monitor test\n"
0281         "   -s  getsockopt cookie test\n");
0282     return 1;
0283 }
0284
0285 static void finish(int ret)
0286 {
0287     test_finish = true;
0288 }
0289
0290 int main(int argc, char *argv[])
0291 {
0292     int opt;
0293     bool cfg_test_traffic = false;
0294     bool cfg_test_cookie = false;
0295
0296     if (argc != 3)
0297         return usage();
0298     while ((opt = getopt(argc, argv, "ts")) != -1) {
0299         switch (opt) {
0300         case 't':
0301             cfg_test_traffic = true;
0302             break;
0303         case 's':
0304             cfg_test_cookie = true;
0305             break;
0306
0307         default:
0308             printf("unknown option %c\n", opt);
0309             usage();
0310             return -1;
0311         }
0312     }
0313     maps_create();
0314     prog_load();
0315     prog_attach_iptables(argv[2]);
0316     if (cfg_test_traffic) {
0317         if (signal(SIGINT, finish) == SIG_ERR)
0318             error(1, errno, "register SIGINT handler failed");
0319         if (signal(SIGTERM, finish) == SIG_ERR)
0320             error(1, errno, "register SIGTERM handler failed");
0321         while (!test_finish) {
0322             print_table();
0323             printf("\n");
0324             sleep(1);
0325         }
0326     } else if (cfg_test_cookie) {
0327         udp_client();
0328     }
0329     close(prog_fd);
0330     close(map_fd);
0331     return 0;
0332 }