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ipc: simplify inflatable buffer and add fuzzer

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Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
This commit is contained in:
Jason A. Donenfeld 2020-01-04 14:46:27 +01:00
parent f59f63f462
commit 1d2d6200b8
5 changed files with 108 additions and 64 deletions
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9
src/fuzz/Makefile
View File

@ -2,10 +2,10 @@
#
# Copyright (C) 2018-2020 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
all: config uapi
all: config uapi stringlist
CFLAGS ?= -O3 -march=native -g
CFLAGS += -fsanitize=fuzzer -std=gnu11 -idirafter ../uapi
CFLAGS += -fsanitize=fuzzer -fsanitize=address -std=gnu11 -idirafter ../uapi
CC := clang
config: config.c ../config.c ../encoding.c
@ -14,7 +14,10 @@ config: config.c ../config.c ../encoding.c
uapi: uapi.c ../ipc.c ../curve25519.c ../encoding.c
$(CC) $(CFLAGS) -o $@ $<
stringlist: stringlist.c ../ipc.c ../curve25519.c ../encoding.c
$(CC) $(CFLAGS) -o $@ $<
clean:
rm -f config uapi
rm -f config uapi stringlist
.PHONY: all clean

2
src/fuzz/config.c
View File

@ -18,7 +18,7 @@
const char *__asan_default_options()
{
return "verbosity=1";
return "verbosity=1";
}
int LLVMFuzzerTestOneInput(const uint8_t *data, size_t len)

59
src/fuzz/stringlist.c Normal file
View File

@ -0,0 +1,59 @@
// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2018-2020 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
*/
#define RUNSTATEDIR "/var/empty"
#undef __linux__
#include "../ipc.c"
#include "../curve25519.c"
#include "../encoding.c"
#include <stdint.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <assert.h>
const char *__asan_default_options()
{
return "verbosity=1";
}
int LLVMFuzzerTestOneInput(const uint8_t *data, size_t data_len)
{
struct string_list list = { 0 };
char *interfaces;
if (!data_len)
return 0;
interfaces = malloc(data_len);
assert(interfaces);
memcpy(interfaces, data, data_len);
interfaces[data_len - 1] = '\0';
for (char *interface = interfaces; interface - interfaces < data_len; interface += strlen(interface) + 1)
assert(string_list_add(&list, interface) == 0);
for (char *interface = interfaces, *interface2 = list.buffer;;) {
size_t len;
if (interface - interfaces >= data_len) {
assert(!interface2 || !strlen(interface2));
break;
}
len = strlen(interface);
if (!len) {
++interface;
continue;
}
assert(strlen(interface2) == len);
assert(!memcmp(interface, interface2, len + 1));
interface += len + 1;
interface2 += len + 1;
}
free(list.buffer);
free(interfaces);
return 0;
}

2
src/fuzz/uapi.c
View File

@ -20,7 +20,7 @@ static FILE *hacked_userspace_interface_file(const char *iface);
const char *__asan_default_options()
{
return "verbosity=1";
return "verbosity=1";
}
union hackiface {

100
src/ipc.c
View File

@ -48,50 +48,34 @@
#define SOCKET_BUFFER_SIZE 8192
#endif
struct inflatable_buffer {
struct string_list {
char *buffer;
char *next;
bool good;
size_t len;
size_t pos;
size_t cap;
};
#define max(a, b) ((a) > (b) ? (a) : (b))
static int add_next_to_inflatable_buffer(struct inflatable_buffer *buffer)
static int string_list_add(struct string_list *list, const char *str)
{
size_t len, expand_to;
char *new_buffer;
size_t len = strlen(str) + 1;
if (!buffer->good || !buffer->next) {
free(buffer->next);
buffer->good = false;
if (len == 1)
return 0;
}
len = strlen(buffer->next) + 1;
if (len >= list->cap - list->len) {
char *new_buffer;
size_t new_cap = list->cap * 2;
if (len == 1) {
free(buffer->next);
buffer->good = false;
return 0;
}
if (buffer->len - buffer->pos <= len) {
expand_to = max(buffer->len * 2, buffer->len + len + 1);
new_buffer = realloc(buffer->buffer, expand_to);
if (!new_buffer) {
free(buffer->next);
buffer->good = false;
if (new_cap < list->len +len + 1)
new_cap = list->len + len + 1;
new_buffer = realloc(list->buffer, new_cap);
if (!new_buffer)
return -errno;
}
memset(&new_buffer[buffer->len], 0, expand_to - buffer->len);
buffer->buffer = new_buffer;
buffer->len = expand_to;
list->buffer = new_buffer;
list->cap = new_cap;
}
memcpy(&buffer->buffer[buffer->pos], buffer->next, len);
free(buffer->next);
buffer->good = false;
buffer->pos += len;
memcpy(list->buffer + list->len, str, len);
list->len += len;
list->buffer[list->len] = '\0';
return 0;
}
@ -167,7 +151,7 @@ static bool userspace_has_wireguard_interface(const char *iface)
return true;
}
static int userspace_get_wireguard_interfaces(struct inflatable_buffer *buffer)
static int userspace_get_wireguard_interfaces(struct string_list *list)
{
DIR *dir;
struct dirent *ent;
@ -188,9 +172,7 @@ static int userspace_get_wireguard_interfaces(struct inflatable_buffer *buffer)
*end = '\0';
if (!userspace_has_wireguard_interface(ent->d_name))
continue;
buffer->next = strdup(ent->d_name);
buffer->good = true;
ret = add_next_to_inflatable_buffer(buffer);
ret = string_list_add(list, ent->d_name);
if (ret < 0)
goto out;
}
@ -451,37 +433,42 @@ err:
#ifdef __linux__
struct interface {
const char *name;
bool is_wireguard;
};
static int parse_linkinfo(const struct nlattr *attr, void *data)
{
struct inflatable_buffer *buffer = data;
struct interface *interface = data;
if (mnl_attr_get_type(attr) == IFLA_INFO_KIND && !strcmp("wireguard", mnl_attr_get_str(attr)))
buffer->good = true;
if (mnl_attr_get_type(attr) == IFLA_INFO_KIND && !strcmp(WG_GENL_NAME, mnl_attr_get_str(attr)))
interface->is_wireguard = true;
return MNL_CB_OK;
}
static int parse_infomsg(const struct nlattr *attr, void *data)
{
struct inflatable_buffer *buffer = data;
struct interface *interface = data;
if (mnl_attr_get_type(attr) == IFLA_LINKINFO)
return mnl_attr_parse_nested(attr, parse_linkinfo, data);
else if (mnl_attr_get_type(attr) == IFLA_IFNAME)
buffer->next = strdup(mnl_attr_get_str(attr));
interface->name = mnl_attr_get_str(attr);
return MNL_CB_OK;
}
static int read_devices_cb(const struct nlmsghdr *nlh, void *data)
{
struct inflatable_buffer *buffer = data;
struct string_list *list = data;
struct interface interface = { 0 };
int ret;
buffer->good = false;
buffer->next = NULL;
ret = mnl_attr_parse(nlh, sizeof(struct ifinfomsg), parse_infomsg, data);
ret = mnl_attr_parse(nlh, sizeof(struct ifinfomsg), parse_infomsg, &interface);
if (ret != MNL_CB_OK)
return ret;
ret = add_next_to_inflatable_buffer(buffer);
if (interface.name && interface.is_wireguard)
ret = string_list_add(list, interface.name);
if (ret < 0)
return ret;
if (nlh->nlmsg_type != NLMSG_DONE)
@ -489,7 +476,7 @@ static int read_devices_cb(const struct nlmsghdr *nlh, void *data)
return MNL_CB_OK;
}
static int kernel_get_wireguard_interfaces(struct inflatable_buffer *buffer)
static int kernel_get_wireguard_interfaces(struct string_list *list)
{
struct mnl_socket *nl = NULL;
char *rtnl_buffer = NULL;
@ -536,7 +523,7 @@ another:
ret = -errno;
goto cleanup;
}
if ((len = mnl_cb_run(rtnl_buffer, len, seq, portid, read_devices_cb, buffer)) < 0) {
if ((len = mnl_cb_run(rtnl_buffer, len, seq, portid, read_devices_cb, list)) < 0) {
/* Netlink returns NLM_F_DUMP_INTR if the set of all tunnels changed
* during the dump. That's unfortunate, but is pretty common on busy
* systems that are adding and removing tunnels all the time. Rather
@ -940,30 +927,25 @@ out:
/* first\0second\0third\0forth\0last\0\0 */
char *ipc_list_devices(void)
{
struct inflatable_buffer buffer = { .len = SOCKET_BUFFER_SIZE };
struct string_list list = { 0 };
int ret;
ret = -ENOMEM;
buffer.buffer = calloc(1, buffer.len);
if (!buffer.buffer)
goto cleanup;
#ifdef __linux__
ret = kernel_get_wireguard_interfaces(&buffer);
ret = kernel_get_wireguard_interfaces(&list);
if (ret < 0)
goto cleanup;
#endif
ret = userspace_get_wireguard_interfaces(&buffer);
ret = userspace_get_wireguard_interfaces(&list);
if (ret < 0)
goto cleanup;
cleanup:
errno = -ret;
if (errno) {
free(buffer.buffer);
free(list.buffer);
return NULL;
}
return buffer.buffer;
return list.buffer ?: strdup("\0");
}
int ipc_get_device(struct wgdevice **dev, const char *iface)