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#include "libhfnetdriver/netdriver.h"
#include <arpa/inet.h>
#include <errno.h>
#include <inttypes.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#if defined(_HF_ARCH_LINUX)
#include <sched.h>
#endif /* defined(_HF_ARCH_LINUX) */
#include "honggfuzz.h"
#include "libhfcommon/common.h"
#include "libhfcommon/files.h"
#include "libhfcommon/log.h"
#include "libhfcommon/ns.h"
#include "libhfcommon/util.h"
__attribute__((visibility("default"))) __attribute__((used))
const char *const LIBHFNETDRIVER_module_netdriver = _HF_NETDRIVER_SIG;
#define HFND_TCP_PORT_ENV "HFND_TCP_PORT"
#define HFND_SKIP_FUZZING_ENV "HFND_SKIP_FUZZING"
static char *initial_server_argv[] = {"fuzzer", NULL};
static struct {
uint16_t tcp_port;
int argc_server;
char **argv_server;
} hfnd_globals = {
.tcp_port = 8080,
.argc_server = 1,
.argv_server = initial_server_argv,
};
__attribute__((weak)) int HonggfuzzNetDriver_main(
int argc HF_ATTR_UNUSED, char **argv HF_ATTR_UNUSED) {
LOG_F("The HonggfuzzNetDriver_main function was not defined in your code");
return EXIT_FAILURE;
}
static void *netDriver_mainProgram(void *unused HF_ATTR_UNUSED) {
int ret = HonggfuzzNetDriver_main(hfnd_globals.argc_server, hfnd_globals.argv_server);
LOG_I("Honggfuzz Net Driver (pid=%d): HonggfuzzNetDriver_main() function exited with: %d",
(int)getpid(), ret);
_exit(ret);
}
static void netDriver_startOriginalProgramInThread(void) {
pthread_t t;
pthread_attr_t attr;
pthread_attr_init(&attr);
pthread_attr_setstacksize(&attr, 1024 * 1024 * 8);
pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
if (pthread_create(&t, &attr, netDriver_mainProgram, NULL) != 0) {
PLOG_F("Couldn't create the 'netDriver_mainProgram' thread");
}
}
static void netDriver_initNsIfNeeded(void) {
static bool initialized = false;
if (initialized) {
return;
}
initialized = true;
#if defined(_HF_ARCH_LINUX)
if (!nsEnter(CLONE_NEWUSER | CLONE_NEWNET | CLONE_NEWNS | CLONE_NEWIPC | CLONE_NEWUTS)) {
LOG_F("nsEnter(CLONE_NEWUSER|CLONE_NEWNET|CLONE_NEWNS|CLONE_NEWIPC|CLONE_NEWUTS) failed");
}
if (!nsIfaceUp("lo")) {
LOG_F("nsIfaceUp('lo') failed");
}
if (mkdir(HFND_TMP_DIR, 0755) == -1 && errno != EEXIST) {
PLOG_F("mkdir('%s', 0755)", HFND_TMP_DIR);
}
if (!nsMountTmpfs(HFND_TMP_DIR)) {
LOG_F("nsMountTmpfs('%s') failed", HFND_TMP_DIR);
}
return;
#endif /* defined(_HF_ARCH_LINUX) */
LOG_W("Honggfuzz Net Driver (pid=%d): Namespaces not enabled for this OS platform",
(int)getpid());
}
/*
* Try to bind the client socket to a random loopback address, to avoid problems with exhausted
* ephemeral ports. We run out of them, because the TIME_WAIT state is imposed on recently closed
* TCP connections originating from the same IP address (127.0.0.1), and connecting to the singular
* IP address (again, 127.0.0.1) on a single port
*/
static void netDriver_bindToRndLoopback(int sock, sa_family_t sa_family) {
if (sa_family != AF_INET) {
return;
}
const struct sockaddr_in bsaddr = {
.sin_family = AF_INET,
.sin_port = htons(0),
.sin_addr.s_addr = htonl((((uint32_t)util_rnd64()) & 0x00FFFFFF) | 0x7F000000),
};
if (bind(sock, (struct sockaddr *)&bsaddr, sizeof(bsaddr)) == -1) {
PLOG_W("Could not bind to a random IPv4 Loopback address");
}
}
static int netDriver_sockConnAddr(const struct sockaddr *addr, socklen_t socklen) {
int sock = socket(addr->sa_family, SOCK_STREAM, 0);
if (sock == -1) {
PLOG_D("socket(type=%d, SOCK_STREAM, 0)", addr->sa_family);
return -1;
}
int val = 1;
if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &val, (socklen_t)sizeof(val)) == -1) {
PLOG_W("setsockopt(sock=%d, SOL_SOCKET, SO_REUSEADDR, 1)", sock);
}
#if defined(SOL_TCP) && defined(TCP_NODELAY)
val = 1;
if (setsockopt(sock, SOL_TCP, TCP_NODELAY, &val, (socklen_t)sizeof(val)) == -1) {
PLOG_W("setsockopt(sock=%d, SOL_TCP, TCP_NODELAY, 1)", sock);
}
#endif /* defined(SOL_TCP) && defined(TCP_NODELAY) */
netDriver_bindToRndLoopback(sock, addr->sa_family);
if (TEMP_FAILURE_RETRY(connect(sock, addr, socklen)) == -1) {
PLOG_D("connect(type=%d, loopback)", addr->sa_family);
close(sock);
return -1;
}
return sock;
}
int netDriver_sockConn(uint16_t portno) {
int sock = -1;
if (portno < 1) {
LOG_F("Specified TCP port (%d) cannot be < 1", portno);
}
/* Try IPv4's 127.0.0.1 first */
const struct sockaddr_in saddr4 = {
.sin_family = AF_INET,
.sin_port = htons(portno),
.sin_addr.s_addr = htonl(INADDR_LOOPBACK),
};
if ((sock = netDriver_sockConnAddr((const struct sockaddr *)&saddr4, sizeof(saddr4))) != -1) {
return sock;
}
/* Next, try IPv6's ::1 */
const struct sockaddr_in6 saddr6 = {
.sin6_family = AF_INET6,
.sin6_port = htons(portno),
.sin6_flowinfo = 0,
.sin6_addr = in6addr_loopback,
.sin6_scope_id = 0,
};
if ((sock = netDriver_sockConnAddr((const struct sockaddr *)&saddr6, sizeof(saddr6))) != -1) {
return sock;
}
LOG_W("Honggfuzz Net Driver (pid=%d): couldn't connect(loopback, port:%" PRIu16 ")",
(int)getpid(), portno);
return -1;
}
/*
* Decide which TCP port should be used for sending inputs
* Define this function in your code to provide custom TCP port choice
*/
__attribute__((weak)) uint16_t HonggfuzzNetDriverPort(
int argc HF_ATTR_UNUSED, char **argv HF_ATTR_UNUSED) {
const char *port_str = getenv(HFND_TCP_PORT_ENV);
if (port_str == NULL) {
return hfnd_globals.tcp_port;
}
errno = 0;
signed long portsl = strtol(port_str, NULL, 0);
if (errno != 0) {
PLOG_F("Couldn't convert '%s'='%s' to a number", HFND_TCP_PORT_ENV, port_str);
}
if (portsl < 1) {
LOG_F("Specified TCP port '%s'='%s' (%ld) cannot be < 1", HFND_TCP_PORT_ENV, port_str,
portsl);
}
if (portsl > 65535) {
LOG_F("Specified TCP port '%s'='%s' (%ld) cannot be > 65535", HFND_TCP_PORT_ENV, port_str,
portsl);
}
return (uint16_t)portsl;
}
/*
* The return value is a number of arguments passed returned to libfuzzer (if used)
*
* Define this function in your code to describe which arguments are passed to the fuzzed
* TCP server, and which to the fuzzing engine.
*/
__attribute__((weak)) int HonggfuzzNetDriverArgsForServer(
int argc, char **argv, int *server_argc, char ***server_argv) {
/* If the used fuzzer is honggfuzz, simply pass all arguments to the TCP server */
__attribute__((weak)) int HonggfuzzMain(int argc, char **argv);
if (HonggfuzzMain) {
*server_argc = argc;
*server_argv = argv;
return argc;
}
/*
* For other fuzzing engines:
* Split: ./httpdserver -max_input=10 -- --config /etc/httpd.confg
* into:
* The fuzzing engine (e.g. libfuzzer) will see "./httpdserver -max_input=10",
* The httpdserver will see: "./httpdserver --config /etc/httpd.confg"
*/
for (int i = 0; i < argc; i++) {
if (strcmp(argv[i], "--") == 0) {
/* Replace '--' with argv[0] */
argv[i] = argv[0];
*server_argc = argc - i;
*server_argv = &argv[i];
return i;
}
}
LOG_I(
"Honggfuzz Net Driver (pid=%d): No '--' was found in the commandline, and therefore no "
"arguments will be passed to the TCP server program",
(int)getpid());
*server_argc = 1;
*server_argv = &argv[0];
return argc;
}
void netDriver_waitForServerReady(uint16_t portno) {
for (;;) {
int fd = netDriver_sockConn(portno);
if (fd >= 0) {
close(fd);
break;
}
LOG_I(
"Honggfuzz Net Driver (pid=%d): Waiting for the TCP server process to start accepting "
"TCP connections at 127.0.0.1:%" PRIu16 ". Sleeping for 0.5 seconds ...",
(int)getpid(), portno);
usleep(500000U);
}
LOG_I(
"Honggfuzz Net Driver (pid=%d): The TCP server process is ready to accept connections at "
"127.0.0.1:%" PRIu16 ". TCP fuzzing starts now!",
(int)getpid(), portno);
}
__attribute__((weak)) int LLVMFuzzerInitialize(int *argc, char ***argv) {
if (getenv(HFND_SKIP_FUZZING_ENV)) {
LOG_I(
"Honggfuzz Net Driver (pid=%d): '%s' is set, skipping fuzzing, calling main() directly",
getpid(), HFND_SKIP_FUZZING_ENV);
if (!HonggfuzzNetDriver_main) {
LOG_F(
"Honggfuzz Net Driver (pid=%d): HonggfuzzNetDriver_main was not defined in your "
"code",
getpid());
}
exit(HonggfuzzNetDriver_main(*argc, *argv));
}
/* Make sure LIBHFNETDRIVER_module_netdriver (NetDriver signature) is used */
LOG_D("Module: %s", LIBHFNETDRIVER_module_netdriver);
hfnd_globals.tcp_port = HonggfuzzNetDriverPort(*argc, *argv);
*argc = HonggfuzzNetDriverArgsForServer(
*argc, *argv, &hfnd_globals.argc_server, &hfnd_globals.argv_server);
LOG_I("Honggfuzz Net Driver (pid=%d): TCP port:%d will be used", (int)getpid(),
hfnd_globals.tcp_port);
netDriver_initNsIfNeeded();
netDriver_startOriginalProgramInThread();
netDriver_waitForServerReady(hfnd_globals.tcp_port);
return 0;
}
__attribute__((weak)) int LLVMFuzzerTestOneInput(const uint8_t *buf, size_t len) {
int sock = netDriver_sockConn(hfnd_globals.tcp_port);
if (sock == -1) {
LOG_F("Couldn't connect to the server TCP port");
}
if (!files_sendToSocket(sock, buf, len)) {
PLOG_E("files_sendToSocket(sock=%d, len=%zu) failed", sock, len);
close(sock);
return 0;
}
/*
* Indicate EOF (via the FIN flag) to the TCP server
*
* Well-behaved TCP servers should process the input and respond/close the TCP connection at
* this point
*/
if (TEMP_FAILURE_RETRY(shutdown(sock, SHUT_WR)) == -1) {
if (errno == ENOTCONN) {
close(sock);
return 0;
}
PLOG_F("shutdown(sock=%d, SHUT_WR)", sock);
}
/*
* Try to read data from the server, assuming that an early TCP close would sometimes cause the
* TCP server to drop the input data, instead of processing it
*/
static char b[1024 * 1024 * 8];
while (TEMP_FAILURE_RETRY(recv(sock, b, sizeof(b), MSG_WAITALL)) > 0)
;
close(sock);
return 0;
}