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