441 lines
9.6 KiB
C
441 lines
9.6 KiB
C
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#include <stdio.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <libelf.h>
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#include <gelf.h>
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#include <errno.h>
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#include <unistd.h>
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#include <string.h>
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#include <stdbool.h>
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#include <stdlib.h>
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#include <linux/bpf.h>
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#include <linux/filter.h>
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#include <linux/perf_event.h>
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#include <sys/syscall.h>
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#include <sys/ioctl.h>
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#include <sys/mman.h>
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#include <poll.h>
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#include <ctype.h>
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#include "libbpf.h"
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#include "bpf_helpers.h"
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#include "bpf_load.h"
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#define DEBUGFS "/sys/kernel/debug/tracing/"
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static char license[128];
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static int kern_version;
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static bool processed_sec[128];
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int map_fd[MAX_MAPS];
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int prog_fd[MAX_PROGS];
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int event_fd[MAX_PROGS];
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int prog_cnt;
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int prog_array_fd = -1;
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static int populate_prog_array(const char *event, int prog_fd)
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{
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int ind = atoi(event), err;
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err = bpf_update_elem(prog_array_fd, &ind, &prog_fd, BPF_ANY);
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if (err < 0) {
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printf("failed to store prog_fd in prog_array\n");
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return -1;
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}
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return 0;
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}
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static int load_and_attach(const char *event, struct bpf_insn *prog, int size)
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{
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bool is_socket = strncmp(event, "socket", 6) == 0;
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bool is_kprobe = strncmp(event, "kprobe/", 7) == 0;
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bool is_kretprobe = strncmp(event, "kretprobe/", 10) == 0;
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bool is_tracepoint = strncmp(event, "tracepoint/", 11) == 0;
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bool is_xdp = strncmp(event, "xdp", 3) == 0;
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bool is_perf_event = strncmp(event, "perf_event", 10) == 0;
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enum bpf_prog_type prog_type;
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char buf[256];
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int fd, efd, err, id;
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struct perf_event_attr attr = {};
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attr.type = PERF_TYPE_TRACEPOINT;
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attr.sample_type = PERF_SAMPLE_RAW;
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attr.sample_period = 1;
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attr.wakeup_events = 1;
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if (is_socket) {
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prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
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} else if (is_kprobe || is_kretprobe) {
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prog_type = BPF_PROG_TYPE_KPROBE;
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} else if (is_tracepoint) {
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prog_type = BPF_PROG_TYPE_TRACEPOINT;
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} else if (is_xdp) {
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prog_type = BPF_PROG_TYPE_XDP;
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} else if (is_perf_event) {
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prog_type = BPF_PROG_TYPE_PERF_EVENT;
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} else {
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printf("Unknown event '%s'\n", event);
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return -1;
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}
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fd = bpf_prog_load(prog_type, prog, size, license, kern_version);
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if (fd < 0) {
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printf("bpf_prog_load() err=%d\n%s", errno, bpf_log_buf);
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return -1;
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}
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prog_fd[prog_cnt++] = fd;
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if (is_xdp || is_perf_event)
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return 0;
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if (is_socket) {
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event += 6;
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if (*event != '/')
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return 0;
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event++;
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if (!isdigit(*event)) {
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printf("invalid prog number\n");
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return -1;
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}
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return populate_prog_array(event, fd);
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}
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if (is_kprobe || is_kretprobe) {
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if (is_kprobe)
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event += 7;
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else
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event += 10;
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if (*event == 0) {
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printf("event name cannot be empty\n");
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return -1;
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}
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if (isdigit(*event))
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return populate_prog_array(event, fd);
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snprintf(buf, sizeof(buf),
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"echo '%c:%s %s' >> /sys/kernel/debug/tracing/kprobe_events",
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is_kprobe ? 'p' : 'r', event, event);
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err = system(buf);
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if (err < 0) {
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printf("failed to create kprobe '%s' error '%s'\n",
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event, strerror(errno));
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return -1;
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}
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strcpy(buf, DEBUGFS);
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strcat(buf, "events/kprobes/");
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strcat(buf, event);
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strcat(buf, "/id");
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} else if (is_tracepoint) {
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event += 11;
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if (*event == 0) {
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printf("event name cannot be empty\n");
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return -1;
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}
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strcpy(buf, DEBUGFS);
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strcat(buf, "events/");
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strcat(buf, event);
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strcat(buf, "/id");
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}
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efd = open(buf, O_RDONLY, 0);
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if (efd < 0) {
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printf("failed to open event %s\n", event);
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return -1;
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}
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err = read(efd, buf, sizeof(buf));
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if (err < 0 || err >= sizeof(buf)) {
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printf("read from '%s' failed '%s'\n", event, strerror(errno));
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return -1;
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}
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close(efd);
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buf[err] = 0;
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id = atoi(buf);
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attr.config = id;
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efd = perf_event_open(&attr, -1/*pid*/, 0/*cpu*/, -1/*group_fd*/, 0);
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if (efd < 0) {
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printf("event %d fd %d err %s\n", id, efd, strerror(errno));
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return -1;
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}
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event_fd[prog_cnt - 1] = efd;
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ioctl(efd, PERF_EVENT_IOC_ENABLE, 0);
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ioctl(efd, PERF_EVENT_IOC_SET_BPF, fd);
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return 0;
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}
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static int load_maps(struct bpf_map_def *maps, int len)
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{
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int i;
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for (i = 0; i < len / sizeof(struct bpf_map_def); i++) {
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map_fd[i] = bpf_create_map(maps[i].type,
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maps[i].key_size,
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maps[i].value_size,
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maps[i].max_entries,
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maps[i].map_flags);
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if (map_fd[i] < 0) {
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printf("failed to create a map: %d %s\n",
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errno, strerror(errno));
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return 1;
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}
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if (maps[i].type == BPF_MAP_TYPE_PROG_ARRAY)
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prog_array_fd = map_fd[i];
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}
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return 0;
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}
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static int get_sec(Elf *elf, int i, GElf_Ehdr *ehdr, char **shname,
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GElf_Shdr *shdr, Elf_Data **data)
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{
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Elf_Scn *scn;
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scn = elf_getscn(elf, i);
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if (!scn)
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return 1;
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if (gelf_getshdr(scn, shdr) != shdr)
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return 2;
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*shname = elf_strptr(elf, ehdr->e_shstrndx, shdr->sh_name);
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if (!*shname || !shdr->sh_size)
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return 3;
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*data = elf_getdata(scn, 0);
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if (!*data || elf_getdata(scn, *data) != NULL)
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return 4;
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return 0;
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}
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static int parse_relo_and_apply(Elf_Data *data, Elf_Data *symbols,
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GElf_Shdr *shdr, struct bpf_insn *insn)
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{
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int i, nrels;
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nrels = shdr->sh_size / shdr->sh_entsize;
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for (i = 0; i < nrels; i++) {
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GElf_Sym sym;
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GElf_Rel rel;
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unsigned int insn_idx;
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gelf_getrel(data, i, &rel);
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insn_idx = rel.r_offset / sizeof(struct bpf_insn);
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gelf_getsym(symbols, GELF_R_SYM(rel.r_info), &sym);
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if (insn[insn_idx].code != (BPF_LD | BPF_IMM | BPF_DW)) {
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printf("invalid relo for insn[%d].code 0x%x\n",
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insn_idx, insn[insn_idx].code);
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return 1;
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}
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insn[insn_idx].src_reg = BPF_PSEUDO_MAP_FD;
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insn[insn_idx].imm = map_fd[sym.st_value / sizeof(struct bpf_map_def)];
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}
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return 0;
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}
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int load_bpf_file(char *path)
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{
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int fd, i;
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Elf *elf;
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GElf_Ehdr ehdr;
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GElf_Shdr shdr, shdr_prog;
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Elf_Data *data, *data_prog, *symbols = NULL;
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char *shname, *shname_prog;
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if (elf_version(EV_CURRENT) == EV_NONE)
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return 1;
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fd = open(path, O_RDONLY, 0);
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if (fd < 0)
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return 1;
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elf = elf_begin(fd, ELF_C_READ, NULL);
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if (!elf)
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return 1;
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if (gelf_getehdr(elf, &ehdr) != &ehdr)
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return 1;
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/* clear all kprobes */
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i = system("echo \"\" > /sys/kernel/debug/tracing/kprobe_events");
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/* scan over all elf sections to get license and map info */
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for (i = 1; i < ehdr.e_shnum; i++) {
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if (get_sec(elf, i, &ehdr, &shname, &shdr, &data))
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continue;
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if (0) /* helpful for llvm debugging */
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printf("section %d:%s data %p size %zd link %d flags %d\n",
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i, shname, data->d_buf, data->d_size,
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shdr.sh_link, (int) shdr.sh_flags);
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if (strcmp(shname, "license") == 0) {
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processed_sec[i] = true;
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memcpy(license, data->d_buf, data->d_size);
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} else if (strcmp(shname, "version") == 0) {
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processed_sec[i] = true;
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if (data->d_size != sizeof(int)) {
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printf("invalid size of version section %zd\n",
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data->d_size);
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return 1;
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}
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memcpy(&kern_version, data->d_buf, sizeof(int));
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} else if (strcmp(shname, "maps") == 0) {
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processed_sec[i] = true;
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if (load_maps(data->d_buf, data->d_size))
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return 1;
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} else if (shdr.sh_type == SHT_SYMTAB) {
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symbols = data;
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}
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}
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/* load programs that need map fixup (relocations) */
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for (i = 1; i < ehdr.e_shnum; i++) {
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if (get_sec(elf, i, &ehdr, &shname, &shdr, &data))
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continue;
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if (shdr.sh_type == SHT_REL) {
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struct bpf_insn *insns;
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if (get_sec(elf, shdr.sh_info, &ehdr, &shname_prog,
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&shdr_prog, &data_prog))
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continue;
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insns = (struct bpf_insn *) data_prog->d_buf;
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processed_sec[shdr.sh_info] = true;
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processed_sec[i] = true;
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if (parse_relo_and_apply(data, symbols, &shdr, insns))
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continue;
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if (memcmp(shname_prog, "kprobe/", 7) == 0 ||
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memcmp(shname_prog, "kretprobe/", 10) == 0 ||
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memcmp(shname_prog, "tracepoint/", 11) == 0 ||
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memcmp(shname_prog, "xdp", 3) == 0 ||
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memcmp(shname_prog, "perf_event", 10) == 0 ||
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memcmp(shname_prog, "socket", 6) == 0)
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load_and_attach(shname_prog, insns, data_prog->d_size);
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}
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}
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/* load programs that don't use maps */
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for (i = 1; i < ehdr.e_shnum; i++) {
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if (processed_sec[i])
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continue;
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if (get_sec(elf, i, &ehdr, &shname, &shdr, &data))
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continue;
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if (memcmp(shname, "kprobe/", 7) == 0 ||
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memcmp(shname, "kretprobe/", 10) == 0 ||
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memcmp(shname, "tracepoint/", 11) == 0 ||
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memcmp(shname, "xdp", 3) == 0 ||
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memcmp(shname, "perf_event", 10) == 0 ||
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memcmp(shname, "socket", 6) == 0)
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load_and_attach(shname, data->d_buf, data->d_size);
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}
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close(fd);
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return 0;
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}
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void read_trace_pipe(void)
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{
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int trace_fd;
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trace_fd = open(DEBUGFS "trace_pipe", O_RDONLY, 0);
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if (trace_fd < 0)
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return;
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while (1) {
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static char buf[4096];
|
||
|
|
ssize_t sz;
|
||
|
|
|
||
|
|
sz = read(trace_fd, buf, sizeof(buf) - 1);
|
||
|
|
if (sz > 0) {
|
||
|
|
buf[sz] = 0;
|
||
|
|
puts(buf);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
#define MAX_SYMS 300000
|
||
|
|
static struct ksym syms[MAX_SYMS];
|
||
|
|
static int sym_cnt;
|
||
|
|
|
||
|
|
static int ksym_cmp(const void *p1, const void *p2)
|
||
|
|
{
|
||
|
|
return ((struct ksym *)p1)->addr - ((struct ksym *)p2)->addr;
|
||
|
|
}
|
||
|
|
|
||
|
|
int load_kallsyms(void)
|
||
|
|
{
|
||
|
|
FILE *f = fopen("/proc/kallsyms", "r");
|
||
|
|
char func[256], buf[256];
|
||
|
|
char symbol;
|
||
|
|
void *addr;
|
||
|
|
int i = 0;
|
||
|
|
|
||
|
|
if (!f)
|
||
|
|
return -ENOENT;
|
||
|
|
|
||
|
|
while (!feof(f)) {
|
||
|
|
if (!fgets(buf, sizeof(buf), f))
|
||
|
|
break;
|
||
|
|
if (sscanf(buf, "%p %c %s", &addr, &symbol, func) != 3)
|
||
|
|
break;
|
||
|
|
if (!addr)
|
||
|
|
continue;
|
||
|
|
syms[i].addr = (long) addr;
|
||
|
|
syms[i].name = strdup(func);
|
||
|
|
i++;
|
||
|
|
}
|
||
|
|
sym_cnt = i;
|
||
|
|
qsort(syms, sym_cnt, sizeof(struct ksym), ksym_cmp);
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
struct ksym *ksym_search(long key)
|
||
|
|
{
|
||
|
|
int start = 0, end = sym_cnt;
|
||
|
|
int result;
|
||
|
|
|
||
|
|
while (start < end) {
|
||
|
|
size_t mid = start + (end - start) / 2;
|
||
|
|
|
||
|
|
result = key - syms[mid].addr;
|
||
|
|
if (result < 0)
|
||
|
|
end = mid;
|
||
|
|
else if (result > 0)
|
||
|
|
start = mid + 1;
|
||
|
|
else
|
||
|
|
return &syms[mid];
|
||
|
|
}
|
||
|
|
|
||
|
|
if (start >= 1 && syms[start - 1].addr < key &&
|
||
|
|
key < syms[start].addr)
|
||
|
|
/* valid ksym */
|
||
|
|
return &syms[start - 1];
|
||
|
|
|
||
|
|
/* out of range. return _stext */
|
||
|
|
return &syms[0];
|
||
|
|
}
|