187 lines
3.7 KiB
C
187 lines
3.7 KiB
C
/*
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* Based on:
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*
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* Minimal BPF JIT image disassembler
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*
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* Disassembles BPF JIT compiler emitted opcodes back to asm insn's for
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* debugging or verification purposes.
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*
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* Copyright 2013 Daniel Borkmann <daniel@iogearbox.net>
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* Licensed under the GNU General Public License, version 2.0 (GPLv2)
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*/
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#define _GNU_SOURCE
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#include <stdio.h>
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#include <stdarg.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <assert.h>
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#include <unistd.h>
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#include <string.h>
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#include <bfd.h>
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#include <dis-asm.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <limits.h>
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#include "json_writer.h"
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#include "main.h"
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static void get_exec_path(char *tpath, size_t size)
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{
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ssize_t len;
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char *path;
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snprintf(tpath, size, "/proc/%d/exe", (int) getpid());
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tpath[size - 1] = 0;
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path = strdup(tpath);
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assert(path);
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len = readlink(path, tpath, size - 1);
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assert(len > 0);
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tpath[len] = 0;
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free(path);
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}
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static int oper_count;
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static int fprintf_json(void *out, const char *fmt, ...)
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{
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va_list ap;
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char *s;
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va_start(ap, fmt);
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if (vasprintf(&s, fmt, ap) < 0)
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return -1;
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va_end(ap);
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if (!oper_count) {
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int i;
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/* Strip trailing spaces */
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i = strlen(s) - 1;
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while (s[i] == ' ')
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s[i--] = '\0';
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jsonw_string_field(json_wtr, "operation", s);
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jsonw_name(json_wtr, "operands");
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jsonw_start_array(json_wtr);
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oper_count++;
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} else if (!strcmp(fmt, ",")) {
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/* Skip */
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} else {
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jsonw_string(json_wtr, s);
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oper_count++;
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}
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free(s);
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return 0;
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}
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void disasm_print_insn(unsigned char *image, ssize_t len, int opcodes,
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const char *arch)
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{
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disassembler_ftype disassemble;
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struct disassemble_info info;
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int count, i, pc = 0;
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char tpath[PATH_MAX];
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bfd *bfdf;
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if (!len)
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return;
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memset(tpath, 0, sizeof(tpath));
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get_exec_path(tpath, sizeof(tpath));
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bfdf = bfd_openr(tpath, NULL);
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assert(bfdf);
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assert(bfd_check_format(bfdf, bfd_object));
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if (json_output)
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init_disassemble_info(&info, stdout,
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(fprintf_ftype) fprintf_json);
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else
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init_disassemble_info(&info, stdout,
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(fprintf_ftype) fprintf);
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/* Update architecture info for offload. */
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if (arch) {
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const bfd_arch_info_type *inf = bfd_scan_arch(arch);
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if (inf) {
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bfdf->arch_info = inf;
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} else {
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p_err("No libfd support for %s", arch);
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return;
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}
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}
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info.arch = bfd_get_arch(bfdf);
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info.mach = bfd_get_mach(bfdf);
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info.buffer = image;
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info.buffer_length = len;
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disassemble_init_for_target(&info);
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#ifdef DISASM_FOUR_ARGS_SIGNATURE
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disassemble = disassembler(info.arch,
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bfd_big_endian(bfdf),
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info.mach,
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bfdf);
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#else
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disassemble = disassembler(bfdf);
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#endif
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assert(disassemble);
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if (json_output)
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jsonw_start_array(json_wtr);
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do {
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if (json_output) {
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jsonw_start_object(json_wtr);
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oper_count = 0;
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jsonw_name(json_wtr, "pc");
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jsonw_printf(json_wtr, "\"0x%x\"", pc);
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} else {
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printf("%4x:\t", pc);
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}
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count = disassemble(pc, &info);
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if (json_output) {
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/* Operand array, was started in fprintf_json. Before
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* that, make sure we have a _null_ value if no operand
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* other than operation code was present.
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*/
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if (oper_count == 1)
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jsonw_null(json_wtr);
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jsonw_end_array(json_wtr);
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}
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if (opcodes) {
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if (json_output) {
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jsonw_name(json_wtr, "opcodes");
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jsonw_start_array(json_wtr);
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for (i = 0; i < count; ++i)
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jsonw_printf(json_wtr, "\"0x%02hhx\"",
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(uint8_t)image[pc + i]);
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jsonw_end_array(json_wtr);
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} else {
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printf("\n\t");
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for (i = 0; i < count; ++i)
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printf("%02x ",
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(uint8_t)image[pc + i]);
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}
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}
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if (json_output)
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jsonw_end_object(json_wtr);
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else
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printf("\n");
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pc += count;
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} while (count > 0 && pc < len);
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if (json_output)
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jsonw_end_array(json_wtr);
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bfd_close(bfdf);
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}
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