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#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/ptrace.h>
#include <sys/resource.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <linux/elf.h>
#include <sys/mman.h>
#include <string.h>
#include <signal.h>
int pid;
static int debug = 0;
struct library_symbol {
char * name;
unsigned long addr;
unsigned char value;
struct library_symbol * next;
};
struct library_symbol * library_symbols = NULL;
static int read_elf(char *filename)
{
struct stat sbuf;
int fd;
void * addr;
struct elf32_hdr * hdr;
Elf32_Shdr * shdr;
struct elf32_sym * symtab = NULL;
int i;
char * strtab = NULL;
u_long symtab_len = 0;
fd = open(filename, O_RDONLY);
if (fd==-1) {
fprintf(stderr, "Can't open \"%s\": %s\n", filename, sys_errlist[errno]);
exit(1);
}
if (fstat(fd, &sbuf)==-1) {
fprintf(stderr, "Can't stat \"%s\": %s\n", filename, sys_errlist[errno]);
exit(1);
}
if (sbuf.st_size < sizeof(struct elf32_hdr)) {
fprintf(stderr, "\"%s\" is not an ELF object\n", filename);
exit(1);
}
addr = mmap(NULL, sbuf.st_size, PROT_READ, MAP_SHARED, fd, 0);
if (addr==(void*)-1) {
fprintf(stderr, "Can't mmap \"%s\": %s\n", filename, sys_errlist[errno]);
exit(1);
}
hdr = addr;
if (strncmp(hdr->e_ident, ELFMAG, SELFMAG)) {
fprintf(stderr, "\"%s\" is not an ELF object\n", filename);
exit(1);
}
for(i=0; i<hdr->e_shnum; i++) {
shdr = addr + hdr->e_shoff + i*hdr->e_shentsize;
if (shdr->sh_type == SHT_DYNSYM) {
if (!symtab) {
#if 0
symtab = (struct elf32_sym *)shdr->sh_addr;
#else
symtab = (struct elf32_sym *)(addr + shdr->sh_offset);
#endif
symtab_len = shdr->sh_size;
}
}
if (shdr->sh_type == SHT_STRTAB) {
if (!strtab) {
#if 0
strtab = (char *)(addr + shdr->sh_offset);
#else
strtab = (char *)(addr + shdr->sh_offset);
#endif
}
}
}
if (debug>0) {
fprintf(stderr, "symtab: 0x%08x\n", (unsigned)symtab);
fprintf(stderr, "symtab_len: %lu\n", symtab_len);
fprintf(stderr, "strtab: 0x%08x\n", (unsigned)strtab);
}
if (!symtab) {
return 0;
}
for(i=0; i<symtab_len/sizeof(struct elf32_sym); i++) {
if (!((symtab+i)->st_shndx) && (symtab+i)->st_value) {
struct library_symbol * tmp = library_symbols;
library_symbols = malloc(sizeof(struct library_symbol));
if (!library_symbols) {
perror("malloc");
exit(1);
}
library_symbols->addr = ((symtab+i)->st_value);
library_symbols->name = strtab+(symtab+i)->st_name;
library_symbols->next = tmp;
if (debug>0) {
fprintf(stderr, "addr: 0x%08x, symbol: \"%s\"\n",
(unsigned)((symtab+i)->st_value),
(strtab+(symtab+i)->st_name));
}
}
}
return 1;
}
int main(int argc, char **argv)
{
int status;
struct library_symbol * tmp = NULL;
while ((argc>1) && (argv[1][0] == '-') && (argv[1][2] == '\0')) {
switch(argv[1][1]) {
case 'd': debug++;
break;
default: fprintf(stderr, "Unknown option '%c'\n", argv[1][1]);
exit(1);
}
argc--; argv++;
}
if (argc<2) {
fprintf(stderr, "Usage: %s [<options>] <program> [<arguments>]\n", argv[0]);
exit(1);
}
if (!read_elf(argv[1])) {
fprintf(stderr, "%s: Not dynamically linked\n", argv[0]);
exit(1);
}
pid = fork();
if (pid<0) {
perror("fork");
exit(1);
} else if (!pid) {
if (ptrace(PTRACE_TRACEME, 0, 1, 0) < 0) {
perror("PTRACE_TRACEME");
exit(1);
}
execvp(argv[1], argv+1);
fprintf(stderr, "Can't execute \"%s\": %s\n", argv[1], sys_errlist[errno]);
exit(1);
}
fprintf(stderr, "pid %u attached\n", pid);
/* Enable breakpoints: */
pid = wait4(-1, &status, 0, NULL);
if (pid==-1) {
perror("wait4");
exit(1);
}
fprintf(stderr, "Enabling breakpoints...\n");
tmp = library_symbols;
while(tmp) {
int a;
a = ptrace(PTRACE_PEEKTEXT, pid, tmp->addr, 0);
tmp->value = a & 0xFF;
a &= 0xFFFFFF00;
a |= 0xCC;
ptrace(PTRACE_POKETEXT, pid, tmp->addr, a);
tmp = tmp->next;
}
ptrace(PTRACE_CONT, pid, 1, 0);
while(1) {
int eip;
int esp;
int function_seen;
pid = wait4(-1, &status, 0, NULL);
if (pid==-1) {
if (errno == ECHILD) {
fprintf(stderr, "No more children\n");
exit(0);
}
perror("wait4");
exit(1);
}
if (WIFEXITED(status)) {
fprintf(stderr, "pid %u exited\n", pid);
continue;
}
if (WIFSIGNALED(status)) {
fprintf(stderr, "pid %u exited on signal %u\n", pid, WTERMSIG(status));
continue;
}
if (!WIFSTOPPED(status)) {
fprintf(stderr, "pid %u ???\n", pid);
continue;
}
if (WSTOPSIG(status) != SIGTRAP) {
fprintf(stderr, "Signal: %u\n", WSTOPSIG(status));
ptrace(PTRACE_CONT, pid, 1, WSTOPSIG(status));
continue;
}
/* pid is stopped... */
eip = ptrace(PTRACE_PEEKUSR, pid, 4*EIP, 0);
esp = ptrace(PTRACE_PEEKUSR, pid, 4*UESP, 0);
#if 0
fprintf(stderr,"EIP = 0x%08x\n", eip);
fprintf(stderr,"ESP = 0x%08x\n", esp);
#endif
fprintf(stderr,"[0x%08x] ", ptrace(PTRACE_PEEKTEXT, pid, esp, 0));
tmp = library_symbols;
function_seen = 0;
while(tmp) {
if (eip == tmp->addr+1) {
int a;
function_seen = 1;
print_function(tmp->name, esp);
a = ptrace(PTRACE_PEEKTEXT, pid, tmp->addr, 0);
a &= 0xFFFFFF00;
a |= tmp->value;
ptrace(PTRACE_POKETEXT, pid, tmp->addr, a);
ptrace(PTRACE_POKEUSR, pid, 4*EIP, eip-1);
ptrace(PTRACE_SINGLESTEP, pid, 0, 0);
pid = wait4(-1, &status, 0, NULL);
if (pid==-1) {
if (errno == ECHILD) {
fprintf(stderr, "No more children\n");
exit(0);
}
perror("wait4");
exit(1);
}
a = ptrace(PTRACE_PEEKTEXT, pid, tmp->addr, 0);
a &= 0xFFFFFF00;
a |= 0xCC;
ptrace(PTRACE_POKETEXT, pid, tmp->addr, a);
ptrace(PTRACE_CONT, pid, 1, 0);
break;
}
tmp = tmp->next;
}
if (!function_seen) {
fprintf(stderr, "pid %u stopped; continuing it...\n", pid);
ptrace(PTRACE_CONT, pid, 1, 0);
}
}
exit(0);
}
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