sharedmem.c

/*

 */

#define AFL_MAIN

#include "config.h"
#include "types.h"
#include "debug.h"
#include "alloc-inl.h"
#include "hash.h"
#include "sharedmem.h"

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <errno.h>
#include <signal.h>
#include <dirent.h>
#include <fcntl.h>

#include <sys/wait.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/resource.h>
#include <sys/mman.h>

#ifndef USEMMAP
 #include <sys/ipc.h>
 #include <sys/shm.h>
#endif

extern unsigned char*trace_bits;

#ifdef USEMMAP
/* ================ Proteas ================ */
int g_shm_fd = -1;
unsigned char *g_shm_base = NULL;
char g_shm_file_path[L_tmpnam];
/* ========================================= */
#else
static s32 shm_id;                    /* ID of the SHM region              */
#endif

/* Get rid of shared memory (atexit handler). */

void remove_shm(void) {
#ifdef USEMMAP
  if (g_shm_base != NULL) {
    munmap(g_shm_base, MAP_SIZE);
    g_shm_base = NULL;
  }

  if (g_shm_fd != -1) {
    close(g_shm_fd);
    g_shm_fd = -1;
  }
#else
  shmctl(shm_id, IPC_RMID, NULL);
#endif
}


/* Configure shared memory. */

void setup_shm(unsigned char dumb_mode) {
#ifdef USEMMAP
  /* generate random file name for multi instance */

  /* thanks to f*cking glibc we can not use tmpnam securely, it generates a security warning that cannot be suppressed */
  /* so we do this worse workaround */
  snprintf(g_shm_file_path, L_tmpnam, "/afl_%d_%ld", getpid(), random());

  /* create the shared memory segment as if it was a file */
  g_shm_fd = shm_open(g_shm_file_path, O_CREAT | O_RDWR | O_EXCL, 0600);
  if (g_shm_fd == -1) {
    PFATAL("shm_open() failed");
  }

  /* configure the size of the shared memory segment */
  if (ftruncate(g_shm_fd, MAP_SIZE)) {
    PFATAL("setup_shm(): ftruncate() failed");
  }

  /* map the shared memory segment to the address space of the process */
  g_shm_base = mmap(0, MAP_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, g_shm_fd, 0);
  if (g_shm_base == MAP_FAILED) {
    close(g_shm_fd);
    g_shm_fd = -1;
    PFATAL("mmap() failed");
  }

  atexit(remove_shm);

  /* If somebody is asking us to fuzz instrumented binaries in dumb mode,
     we don't want them to detect instrumentation, since we won't be sending
     fork server commands. This should be replaced with better auto-detection
     later on, perhaps? */

  if (!dumb_mode) setenv(SHM_ENV_VAR, g_shm_file_path, 1);

  trace_bits = g_shm_base;

  if (!trace_bits) PFATAL("mmap() failed");
  
#else
  u8* shm_str;

  shm_id = shmget(IPC_PRIVATE, MAP_SIZE, IPC_CREAT | IPC_EXCL | 0600);

  if (shm_id < 0) PFATAL("shmget() failed");

  atexit(remove_shm);

  shm_str = alloc_printf("%d", shm_id);

  setenv(SHM_ENV_VAR, shm_str, 1);

  /* If somebody is asking us to fuzz instrumented binaries in dumb mode,
     we don't want them to detect instrumentation, since we won't be sending
     fork server commands. This should be replaced with better auto-detection
     later on, perhaps? */

  if (!dumb_mode) setenv(SHM_ENV_VAR, shm_str, 1);

  ck_free(shm_str);

  trace_bits = shmat(shm_id, NULL, 0);
  
  if (!trace_bits) PFATAL("shmat() failed");

#endif
}