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/*
american fuzzy lop++ - shared memory related code
-------------------------------------------------
Originally written by Michal Zalewski
Forkserver design by Jann Horn <jannhorn@googlemail.com>
Now maintained by Marc Heuse <mh@mh-sec.de>,
Heiko Eißfeldt <heiko.eissfeldt@hexco.de> and
Andrea Fioraldi <andreafioraldi@gmail.com>
Copyright 2016, 2017 Google Inc. All rights reserved.
Copyright 2019-2023 AFLplusplus Project. All rights reserved.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at:
https://www.apache.org/licenses/LICENSE-2.0
Shared code to handle the shared memory. This is used by the fuzzer
as well the other components like afl-tmin, afl-showmap, etc...
*/
#define AFL_MAIN
#ifdef __ANDROID__
#include "android-ashmem.h"
#endif
#include "config.h"
#include "types.h"
#include "debug.h"
#include "alloc-inl.h"
#include "hash.h"
#include "sharedmem.h"
#include "cmplog.h"
#include "list.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
static list_t shm_list = {.element_prealloc_count = 0};
/* Get rid of shared memory. */
void afl_shm_deinit(sharedmem_t *shm) {
if (shm == NULL) { return; }
list_remove(&shm_list, shm);
if (shm->shmemfuzz_mode) {
unsetenv(SHM_FUZZ_ENV_VAR);
} else {
unsetenv(SHM_ENV_VAR);
}
#ifdef USEMMAP
if (shm->map != NULL) {
munmap(shm->map, shm->map_size);
shm->map = NULL;
}
if (shm->g_shm_fd != -1) {
close(shm->g_shm_fd);
shm->g_shm_fd = -1;
}
if (shm->g_shm_file_path[0]) {
shm_unlink(shm->g_shm_file_path);
shm->g_shm_file_path[0] = 0;
}
if (shm->cmplog_mode) {
unsetenv(CMPLOG_SHM_ENV_VAR);
if (shm->cmp_map != NULL) {
munmap(shm->cmp_map, shm->map_size);
shm->cmp_map = NULL;
}
if (shm->cmplog_g_shm_fd != -1) {
close(shm->cmplog_g_shm_fd);
shm->cmplog_g_shm_fd = -1;
}
if (shm->cmplog_g_shm_file_path[0]) {
shm_unlink(shm->cmplog_g_shm_file_path);
shm->cmplog_g_shm_file_path[0] = 0;
}
}
#else
shmctl(shm->shm_id, IPC_RMID, NULL);
if (shm->cmplog_mode) { shmctl(shm->cmplog_shm_id, IPC_RMID, NULL); }
#endif
shm->map = NULL;
}
/* Configure shared memory.
Returns a pointer to shm->map for ease of use.
*/
u8 *afl_shm_init(sharedmem_t *shm, size_t map_size,
unsigned char non_instrumented_mode) {
shm->map_size = 0;
shm->map = NULL;
shm->cmp_map = NULL;
#ifdef USEMMAP
shm->g_shm_fd = -1;
shm->cmplog_g_shm_fd = -1;
const int shmflags = O_RDWR | O_EXCL;
/* ======
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(shm->g_shm_file_path, L_tmpnam, "/afl_%d_%ld", getpid(), random());
#ifdef SHM_LARGEPAGE_ALLOC_DEFAULT
/* trying to get large memory segment optimised and monitorable separately as
* such */
static size_t sizes[4] = {(size_t)-1};
static int psizes = 0;
int i;
if (sizes[0] == (size_t)-1) { psizes = getpagesizes(sizes, 4); }
/* very unlikely to fail even if the arch supports only two sizes */
if (likely(psizes > 0)) {
for (i = psizes - 1; shm->g_shm_fd == -1 && i >= 0; --i) {
if (sizes[i] == 0 || map_size % sizes[i]) { continue; }
shm->g_shm_fd =
shm_create_largepage(shm->g_shm_file_path, shmflags, i,
SHM_LARGEPAGE_ALLOC_DEFAULT, DEFAULT_PERMISSION);
}
}
#endif
/* create the shared memory segment as if it was a file */
if (shm->g_shm_fd == -1) {
shm->g_shm_fd =
shm_open(shm->g_shm_file_path, shmflags | O_CREAT, DEFAULT_PERMISSION);
}
if (shm->g_shm_fd == -1) { PFATAL("shm_open() failed"); }
/* configure the size of the shared memory segment */
if (ftruncate(shm->g_shm_fd, map_size)) {
PFATAL("setup_shm(): ftruncate() failed");
}
/* map the shared memory segment to the address space of the process */
shm->map =
mmap(0, map_size, PROT_READ | PROT_WRITE, MAP_SHARED, shm->g_shm_fd, 0);
if (shm->map == MAP_FAILED) {
close(shm->g_shm_fd);
shm->g_shm_fd = -1;
shm_unlink(shm->g_shm_file_path);
shm->g_shm_file_path[0] = 0;
PFATAL("mmap() failed");
}
/* If somebody is asking us to fuzz instrumented binaries in non-instrumented
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 (!non_instrumented_mode) setenv(SHM_ENV_VAR, shm->g_shm_file_path, 1);
if (shm->map == (void *)-1 || !shm->map) PFATAL("mmap() failed");
if (shm->cmplog_mode) {
snprintf(shm->cmplog_g_shm_file_path, L_tmpnam, "/afl_cmplog_%d_%ld",
getpid(), random());
/* create the shared memory segment as if it was a file */
shm->cmplog_g_shm_fd =
shm_open(shm->cmplog_g_shm_file_path, O_CREAT | O_RDWR | O_EXCL,
DEFAULT_PERMISSION);
if (shm->cmplog_g_shm_fd == -1) { PFATAL("shm_open() failed"); }
/* configure the size of the shared memory segment */
if (ftruncate(shm->cmplog_g_shm_fd, map_size)) {
PFATAL("setup_shm(): cmplog ftruncate() failed");
}
/* map the shared memory segment to the address space of the process */
shm->cmp_map = mmap(0, map_size, PROT_READ | PROT_WRITE, MAP_SHARED,
shm->cmplog_g_shm_fd, 0);
if (shm->cmp_map == MAP_FAILED) {
close(shm->cmplog_g_shm_fd);
shm->cmplog_g_shm_fd = -1;
shm_unlink(shm->cmplog_g_shm_file_path);
shm->cmplog_g_shm_file_path[0] = 0;
PFATAL("mmap() failed");
}
/* If somebody is asking us to fuzz instrumented binaries in
non-instrumented 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 (!non_instrumented_mode)
setenv(CMPLOG_SHM_ENV_VAR, shm->cmplog_g_shm_file_path, 1);
if (shm->cmp_map == (void *)-1 || !shm->cmp_map)
PFATAL("cmplog mmap() failed");
}
#else
u8 *shm_str;
// for qemu+unicorn we have to increase by 8 to account for potential
// compcov map overwrite
shm->shm_id =
shmget(IPC_PRIVATE, map_size == MAP_SIZE ? map_size + 8 : map_size,
IPC_CREAT | IPC_EXCL | DEFAULT_PERMISSION);
if (shm->shm_id < 0) {
PFATAL("shmget() failed, try running afl-system-config");
}
if (shm->cmplog_mode) {
shm->cmplog_shm_id = shmget(IPC_PRIVATE, sizeof(struct cmp_map),
IPC_CREAT | IPC_EXCL | DEFAULT_PERMISSION);
if (shm->cmplog_shm_id < 0) {
shmctl(shm->shm_id, IPC_RMID, NULL); // do not leak shmem
PFATAL("shmget() failed, try running afl-system-config");
}
}
if (!non_instrumented_mode) {
shm_str = alloc_printf("%d", shm->shm_id);
/* If somebody is asking us to fuzz instrumented binaries in
non-instrumented 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? */
setenv(SHM_ENV_VAR, shm_str, 1);
ck_free(shm_str);
}
if (shm->cmplog_mode && !non_instrumented_mode) {
shm_str = alloc_printf("%d", shm->cmplog_shm_id);
setenv(CMPLOG_SHM_ENV_VAR, shm_str, 1);
ck_free(shm_str);
}
shm->map = shmat(shm->shm_id, NULL, 0);
if (shm->map == (void *)-1 || !shm->map) {
shmctl(shm->shm_id, IPC_RMID, NULL); // do not leak shmem
if (shm->cmplog_mode) {
shmctl(shm->cmplog_shm_id, IPC_RMID, NULL); // do not leak shmem
}
PFATAL("shmat() failed");
}
if (shm->cmplog_mode) {
shm->cmp_map = shmat(shm->cmplog_shm_id, NULL, 0);
if (shm->cmp_map == (void *)-1 || !shm->cmp_map) {
shmctl(shm->shm_id, IPC_RMID, NULL); // do not leak shmem
shmctl(shm->cmplog_shm_id, IPC_RMID, NULL); // do not leak shmem
PFATAL("shmat() failed");
}
}
#endif
shm->map_size = map_size;
list_append(&shm_list, shm);
return shm->map;
}
|
