![Alexei Starovoitov](/assets/img/avatar_default.png)
eBPF programs attached to kprobes need to filter based on current->pid, uid and other fields, so introduce helper functions: u64 bpf_get_current_pid_tgid(void) Return: current->tgid << 32 | current->pid u64 bpf_get_current_uid_gid(void) Return: current_gid << 32 | current_uid bpf_get_current_comm(char *buf, int size_of_buf) stores current->comm into buf They can be used from the programs attached to TC as well to classify packets based on current task fields. Update tracex2 example to print histogram of write syscalls for each process instead of aggregated for all. Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
145 lines
2.9 KiB
C
145 lines
2.9 KiB
C
#include <stdio.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <signal.h>
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#include <linux/bpf.h>
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#include <string.h>
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#include "libbpf.h"
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#include "bpf_load.h"
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#define MAX_INDEX 64
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#define MAX_STARS 38
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static void stars(char *str, long val, long max, int width)
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{
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int i;
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for (i = 0; i < (width * val / max) - 1 && i < width - 1; i++)
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str[i] = '*';
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if (val > max)
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str[i - 1] = '+';
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str[i] = '\0';
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}
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struct task {
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char comm[16];
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__u64 pid_tgid;
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__u64 uid_gid;
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};
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struct hist_key {
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struct task t;
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__u32 index;
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};
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#define SIZE sizeof(struct task)
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static void print_hist_for_pid(int fd, void *task)
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{
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struct hist_key key = {}, next_key;
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char starstr[MAX_STARS];
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long value;
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long data[MAX_INDEX] = {};
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int max_ind = -1;
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long max_value = 0;
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int i, ind;
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while (bpf_get_next_key(fd, &key, &next_key) == 0) {
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if (memcmp(&next_key, task, SIZE)) {
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key = next_key;
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continue;
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}
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bpf_lookup_elem(fd, &next_key, &value);
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ind = next_key.index;
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data[ind] = value;
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if (value && ind > max_ind)
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max_ind = ind;
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if (value > max_value)
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max_value = value;
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key = next_key;
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}
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printf(" syscall write() stats\n");
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printf(" byte_size : count distribution\n");
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for (i = 1; i <= max_ind + 1; i++) {
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stars(starstr, data[i - 1], max_value, MAX_STARS);
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printf("%8ld -> %-8ld : %-8ld |%-*s|\n",
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(1l << i) >> 1, (1l << i) - 1, data[i - 1],
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MAX_STARS, starstr);
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}
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}
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static void print_hist(int fd)
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{
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struct hist_key key = {}, next_key;
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static struct task tasks[1024];
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int task_cnt = 0;
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int i;
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while (bpf_get_next_key(fd, &key, &next_key) == 0) {
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int found = 0;
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for (i = 0; i < task_cnt; i++)
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if (memcmp(&tasks[i], &next_key, SIZE) == 0)
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found = 1;
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if (!found)
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memcpy(&tasks[task_cnt++], &next_key, SIZE);
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key = next_key;
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}
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for (i = 0; i < task_cnt; i++) {
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printf("\npid %d cmd %s uid %d\n",
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(__u32) tasks[i].pid_tgid,
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tasks[i].comm,
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(__u32) tasks[i].uid_gid);
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print_hist_for_pid(fd, &tasks[i]);
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}
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}
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static void int_exit(int sig)
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{
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print_hist(map_fd[1]);
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exit(0);
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}
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int main(int ac, char **argv)
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{
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char filename[256];
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long key, next_key, value;
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FILE *f;
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int i;
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snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
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signal(SIGINT, int_exit);
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/* start 'ping' in the background to have some kfree_skb events */
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f = popen("ping -c5 localhost", "r");
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(void) f;
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/* start 'dd' in the background to have plenty of 'write' syscalls */
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f = popen("dd if=/dev/zero of=/dev/null count=5000000", "r");
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(void) f;
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if (load_bpf_file(filename)) {
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printf("%s", bpf_log_buf);
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return 1;
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}
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for (i = 0; i < 5; i++) {
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key = 0;
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while (bpf_get_next_key(map_fd[0], &key, &next_key) == 0) {
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bpf_lookup_elem(map_fd[0], &next_key, &value);
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printf("location 0x%lx count %ld\n", next_key, value);
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key = next_key;
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}
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if (key)
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printf("\n");
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sleep(1);
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}
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print_hist(map_fd[1]);
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return 0;
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}
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