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TOMOYO Linux Cross Reference
Linux/samples/bpf/cookie_uid_helper_example.c

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  1 /* This test is a demo of using get_socket_uid and get_socket_cookie
  2  * helper function to do per socket based network traffic monitoring.
  3  * It requires iptables version higher then 1.6.1. to load pinned eBPF
  4  * program into the xt_bpf match.
  5  *
  6  * TEST:
  7  * ./run_cookie_uid_helper_example.sh -option
  8  * option:
  9  *      -t: do traffic monitoring test, the program will continuously
 10  * print out network traffic happens after program started A sample
 11  * output is shown below:
 12  *
 13  * cookie: 877, uid: 0x3e8, Pakcet Count: 20, Bytes Count: 11058
 14  * cookie: 132, uid: 0x0, Pakcet Count: 2, Bytes Count: 286
 15  * cookie: 812, uid: 0x3e8, Pakcet Count: 3, Bytes Count: 1726
 16  * cookie: 802, uid: 0x3e8, Pakcet Count: 2, Bytes Count: 104
 17  * cookie: 877, uid: 0x3e8, Pakcet Count: 20, Bytes Count: 11058
 18  * cookie: 831, uid: 0x3e8, Pakcet Count: 2, Bytes Count: 104
 19  * cookie: 0, uid: 0x0, Pakcet Count: 6, Bytes Count: 712
 20  * cookie: 880, uid: 0xfffe, Pakcet Count: 1, Bytes Count: 70
 21  *
 22  *      -s: do getsockopt SO_COOKIE test, the program will set up a pair of
 23  * UDP sockets and send packets between them. And read out the traffic data
 24  * directly from the ebpf map based on the socket cookie.
 25  *
 26  * Clean up: if using shell script, the script file will delete the iptables
 27  * rule and unmount the bpf program when exit. Else the iptables rule need
 28  * to be deleted by hand, see run_cookie_uid_helper_example.sh for detail.
 29  */
 30 
 31 #define _GNU_SOURCE
 32 
 33 #define offsetof(type, member)  __builtin_offsetof(type, member)
 34 #define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))
 35 
 36 #include <arpa/inet.h>
 37 #include <errno.h>
 38 #include <error.h>
 39 #include <limits.h>
 40 #include <linux/bpf.h>
 41 #include <linux/if_ether.h>
 42 #include <net/if.h>
 43 #include <signal.h>
 44 #include <stdbool.h>
 45 #include <stdint.h>
 46 #include <stdio.h>
 47 #include <stdlib.h>
 48 #include <string.h>
 49 #include <sys/socket.h>
 50 #include <sys/stat.h>
 51 #include <sys/types.h>
 52 #include <unistd.h>
 53 #include <bpf/bpf.h>
 54 #include "bpf_insn.h"
 55 
 56 #define PORT 8888
 57 
 58 struct stats {
 59         uint32_t uid;
 60         uint64_t packets;
 61         uint64_t bytes;
 62 };
 63 
 64 static int map_fd, prog_fd;
 65 
 66 static bool test_finish;
 67 
 68 static void maps_create(void)
 69 {
 70         map_fd = bpf_create_map(BPF_MAP_TYPE_HASH, sizeof(uint32_t),
 71                                 sizeof(struct stats), 100, 0);
 72         if (map_fd < 0)
 73                 error(1, errno, "map create failed!\n");
 74 }
 75 
 76 static void prog_load(void)
 77 {
 78         static char log_buf[1 << 16];
 79 
 80         struct bpf_insn prog[] = {
 81                 /*
 82                  * Save sk_buff for future usage. value stored in R6 to R10 will
 83                  * not be reset after a bpf helper function call.
 84                  */
 85                 BPF_MOV64_REG(BPF_REG_6, BPF_REG_1),
 86                 /*
 87                  * pc1: BPF_FUNC_get_socket_cookie takes one parameter,
 88                  * R1: sk_buff
 89                  */
 90                 BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
 91                                 BPF_FUNC_get_socket_cookie),
 92                 /* pc2-4: save &socketCookie to r7 for future usage*/
 93                 BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_0, -8),
 94                 BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
 95                 BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
 96                 /*
 97                  * pc5-8: set up the registers for BPF_FUNC_map_lookup_elem,
 98                  * it takes two parameters (R1: map_fd,  R2: &socket_cookie)
 99                  */
100                 BPF_LD_MAP_FD(BPF_REG_1, map_fd),
101                 BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
102                 BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
103                                 BPF_FUNC_map_lookup_elem),
104                 /*
105                  * pc9. if r0 != 0x0, go to pc+14, since we have the cookie
106                  * stored already
107                  * Otherwise do pc10-22 to setup a new data entry.
108                  */
109                 BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 14),
110                 BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
111                 BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
112                                 BPF_FUNC_get_socket_uid),
113                 /*
114                  * Place a struct stats in the R10 stack and sequentially
115                  * place the member value into the memory. Packets value
116                  * is set by directly place a IMM value 1 into the stack.
117                  */
118                 BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_0,
119                             -32 + (__s16)offsetof(struct stats, uid)),
120                 BPF_ST_MEM(BPF_DW, BPF_REG_10,
121                            -32 + (__s16)offsetof(struct stats, packets), 1),
122                 /*
123                  * __sk_buff is a special struct used for eBPF program to
124                  * directly access some sk_buff field.
125                  */
126                 BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_6,
127                                 offsetof(struct __sk_buff, len)),
128                 BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_1,
129                             -32 + (__s16)offsetof(struct stats, bytes)),
130                 /*
131                  * add new map entry using BPF_FUNC_map_update_elem, it takes
132                  * 4 parameters (R1: map_fd, R2: &socket_cookie, R3: &stats,
133                  * R4: flags)
134                  */
135                 BPF_LD_MAP_FD(BPF_REG_1, map_fd),
136                 BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
137                 BPF_MOV64_REG(BPF_REG_3, BPF_REG_10),
138                 BPF_ALU64_IMM(BPF_ADD, BPF_REG_3, -32),
139                 BPF_MOV64_IMM(BPF_REG_4, 0),
140                 BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
141                                 BPF_FUNC_map_update_elem),
142                 BPF_JMP_IMM(BPF_JA, 0, 0, 5),
143                 /*
144                  * pc24-30 update the packet info to a exist data entry, it can
145                  * be done by directly write to pointers instead of using
146                  * BPF_FUNC_map_update_elem helper function
147                  */
148                 BPF_MOV64_REG(BPF_REG_9, BPF_REG_0),
149                 BPF_MOV64_IMM(BPF_REG_1, 1),
150                 BPF_STX_XADD(BPF_DW, BPF_REG_9, BPF_REG_1,
151                                 offsetof(struct stats, packets)),
152                 BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_6,
153                                 offsetof(struct __sk_buff, len)),
154                 BPF_STX_XADD(BPF_DW, BPF_REG_9, BPF_REG_1,
155                                 offsetof(struct stats, bytes)),
156                 BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_6,
157                                 offsetof(struct __sk_buff, len)),
158                 BPF_EXIT_INSN(),
159         };
160         prog_fd = bpf_load_program(BPF_PROG_TYPE_SOCKET_FILTER, prog,
161                                         ARRAY_SIZE(prog), "GPL", 0,
162                                         log_buf, sizeof(log_buf));
163         if (prog_fd < 0)
164                 error(1, errno, "failed to load prog\n%s\n", log_buf);
165 }
166 
167 static void prog_attach_iptables(char *file)
168 {
169         int ret;
170         char rules[100];
171 
172         if (bpf_obj_pin(prog_fd, file))
173                 error(1, errno, "bpf_obj_pin");
174         if (strlen(file) > 50) {
175                 printf("file path too long: %s\n", file);
176                 exit(1);
177         }
178         sprintf(rules, "iptables -A OUTPUT -m bpf --object-pinned %s -j ACCEPT",
179                 file);
180         ret = system(rules);
181         if (ret < 0) {
182                 printf("iptables rule update failed: %d/n", WEXITSTATUS(ret));
183                 exit(1);
184         }
185 }
186 
187 static void print_table(void)
188 {
189         struct stats curEntry;
190         uint32_t curN = UINT32_MAX;
191         uint32_t nextN;
192         int res;
193 
194         while (bpf_map_get_next_key(map_fd, &curN, &nextN) > -1) {
195                 curN = nextN;
196                 res = bpf_map_lookup_elem(map_fd, &curN, &curEntry);
197                 if (res < 0) {
198                         error(1, errno, "fail to get entry value of Key: %u\n",
199                                 curN);
200                 } else {
201                         printf("cookie: %u, uid: 0x%x, Packet Count: %lu,"
202                                 " Bytes Count: %lu\n", curN, curEntry.uid,
203                                 curEntry.packets, curEntry.bytes);
204                 }
205         }
206 }
207 
208 static void udp_client(void)
209 {
210         struct sockaddr_in si_other = {0};
211         struct sockaddr_in si_me = {0};
212         struct stats dataEntry;
213         int s_rcv, s_send, i, recv_len;
214         char message = 'a';
215         char buf;
216         uint64_t cookie;
217         int res;
218         socklen_t cookie_len = sizeof(cookie);
219         socklen_t slen = sizeof(si_other);
220 
221         s_rcv = socket(PF_INET, SOCK_DGRAM, 0);
222         if (s_rcv < 0)
223                 error(1, errno, "rcv socket creat failed!\n");
224         si_other.sin_family = AF_INET;
225         si_other.sin_port = htons(PORT);
226         if (inet_aton("127.0.0.1", &si_other.sin_addr) == 0)
227                 error(1, errno, "inet_aton\n");
228         if (bind(s_rcv, (struct sockaddr *)&si_other, sizeof(si_other)) == -1)
229                 error(1, errno, "bind\n");
230         s_send = socket(PF_INET, SOCK_DGRAM, 0);
231         if (s_send < 0)
232                 error(1, errno, "send socket creat failed!\n");
233         res = getsockopt(s_send, SOL_SOCKET, SO_COOKIE, &cookie, &cookie_len);
234         if (res < 0)
235                 printf("get cookie failed: %s\n", strerror(errno));
236         res = bpf_map_lookup_elem(map_fd, &cookie, &dataEntry);
237         if (res != -1)
238                 error(1, errno, "socket stat found while flow not active\n");
239         for (i = 0; i < 10; i++) {
240                 res = sendto(s_send, &message, sizeof(message), 0,
241                              (struct sockaddr *)&si_other, slen);
242                 if (res == -1)
243                         error(1, errno, "send\n");
244                 if (res != sizeof(message))
245                         error(1, 0, "%uB != %luB\n", res, sizeof(message));
246                 recv_len = recvfrom(s_rcv, &buf, sizeof(buf), 0,
247                              (struct sockaddr *)&si_me, &slen);
248                 if (recv_len < 0)
249                         error(1, errno, "receive\n");
250                 res = memcmp(&(si_other.sin_addr), &(si_me.sin_addr),
251                            sizeof(si_me.sin_addr));
252                 if (res != 0)
253                         error(1, EFAULT, "sender addr error: %d\n", res);
254                 printf("Message received: %c\n", buf);
255                 res = bpf_map_lookup_elem(map_fd, &cookie, &dataEntry);
256                 if (res < 0)
257                         error(1, errno, "lookup sk stat failed, cookie: %lu\n",
258                               cookie);
259                 printf("cookie: %lu, uid: 0x%x, Packet Count: %lu,"
260                         " Bytes Count: %lu\n\n", cookie, dataEntry.uid,
261                         dataEntry.packets, dataEntry.bytes);
262         }
263         close(s_send);
264         close(s_rcv);
265 }
266 
267 static int usage(void)
268 {
269         printf("Usage: ./run_cookie_uid_helper_example.sh"
270                 " bpfObjName -option\n"
271                 "       -t      traffic monitor test\n"
272                 "       -s      getsockopt cookie test\n");
273         return 1;
274 }
275 
276 static void finish(int ret)
277 {
278         test_finish = true;
279 }
280 
281 int main(int argc, char *argv[])
282 {
283         int opt;
284         bool cfg_test_traffic = false;
285         bool cfg_test_cookie = false;
286 
287         if (argc != 3)
288                 return usage();
289         while ((opt = getopt(argc, argv, "ts")) != -1) {
290                 switch (opt) {
291                 case 't':
292                         cfg_test_traffic = true;
293                         break;
294                 case 's':
295                         cfg_test_cookie = true;
296                         break;
297 
298                 default:
299                         printf("unknown option %c\n", opt);
300                         usage();
301                         return -1;
302                 }
303         }
304         maps_create();
305         prog_load();
306         prog_attach_iptables(argv[2]);
307         if (cfg_test_traffic) {
308                 if (signal(SIGINT, finish) == SIG_ERR)
309                         error(1, errno, "register SIGINT handler failed");
310                 if (signal(SIGTERM, finish) == SIG_ERR)
311                         error(1, errno, "register SIGTERM handler failed");
312                 while (!test_finish) {
313                         print_table();
314                         printf("\n");
315                         sleep(1);
316                 };
317         } else if (cfg_test_cookie) {
318                 udp_client();
319         }
320         close(prog_fd);
321         close(map_fd);
322         return 0;
323 }
324 

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