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parasite.c
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parasite.c
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/*
* Copyright (C) 2022 Liberty Global Service B.V.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, version 2
* of the license.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this library; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include <sys/types.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/mman.h>
#include "memcr.h"
#include "arch/syscall.h"
#define VERBOSE 1
#define __stringify_1(x...) #x
#define __stringify(x...) __stringify_1(x)
#define BOOM() do { *((int *)NULL) = 1; } while (0)
static int finish;
#if VERBOSE == 1
static char *long_to_str(long v)
{
static char buf[sizeof(unsigned long) * 3];
char *p = buf + sizeof(buf) - 1;
int minus = 0;
*p = '\0';
if (v == 0) {
*--p = '0';
return p;
}
if (v < 0) {
minus = 1;
v = -v;
}
while (v) {
*--p = '0' + (v % 10);
v /= 10;
}
if (minus)
*--p = '-';
return p;
}
static char *ulong_to_hstr(unsigned long v)
{
static char buf[sizeof(unsigned long) * 3];
char *p = buf + sizeof(buf) - 1;
unsigned char x;
*p = '\0';
if (v == 0) {
*--p = '0';
return p;
}
while (v) {
x = v % 16;
*--p = x > 9 ? ('a' + (x - 10)) : '0' + x;
v /= 16;
}
return p;
}
static void print_msg(int fd, const char *msg)
{
int size;
for (size = 0; msg[size] != '\0'; size++)
;
sys_write(fd, msg, size);
}
#define __DEBUG__ do { \
print_msg(1, __func__); \
print_msg(1, "() +" __stringify(__LINE__) "\n"); \
} while (0);
#define print_err(fd, txt, ret) do { \
print_msg((fd), __func__); \
print_msg((fd), "() +" __stringify(__LINE__) ": " txt); \
print_msg((fd), long_to_str(ret)); \
print_msg((fd), "\n"); \
} while (0);
#define die(txt, ret) do { \
print_msg(2, __func__); \
print_msg(2, "() +" __stringify(__LINE__) ": " txt); \
print_msg(2, long_to_str(ret)); \
print_msg(2, "\n"); \
*((int *)NULL) = 1; \
} while (0);
#else /* VERBOSE*/
#define print_msg(fd, msg) {}
#define __DEBUG__
#define print_err(fd, txt, ret) {}
#define die(txt, ret) { \
*((int *)NULL) = 1; \
}
#endif
static void xstrcpy(char *dst, char *src)
{
int idx;
for (idx = 0; src[idx] != '\0'; idx++)
dst[idx] = src[idx];
dst[idx + 1] = '\0';
}
static int xread(int fd, void *buf, int size)
{
int ret;
int off = 0;
while (1) {
ret = sys_read(fd, buf + off, size - off);
if (ret == 0)
break;
if (ret < 0) {
print_err(2, "sys_read() failed with ret ", ret);
break;
}
if (ret < size - off) {
off += ret;
continue;
}
return size;
}
return ret;
}
static int xwrite(int fd, void *buf, int size)
{
int ret;
int off = 0;
while (1) {
ret = sys_write(fd, buf + off, size - off);
if (ret < 0) {
print_err(2, "sys_write() failed with ret ", ret);
break;
}
if (ret < size - off) {
off += ret;
continue;
}
return size;
}
return ret;
}
static int cmd_mprotect(int cd)
{
int ret;
struct vm_mprotect req;
while (1) {
ret = xread(cd, &req, sizeof(req));
if (ret == 0)
break;
if (ret < 0) {
print_err(2, "xread() failed with ret ", ret);
BOOM();
}
ret = sys_mprotect(req.addr, req.len, req.prot);
if (ret == -1) {
print_err(2, "sys_mprotect() failed with ret ", ret);
BOOM();
}
}
return 0;
}
static int cmd_get_pages(int cd)
{
int ret;
struct vm_region_req req;
while (1) {
ret = xread(cd, &req, sizeof(req));
if (ret == 0)
break;
if (ret < 0) {
print_err(2, "xread() failed with ret ", ret);
BOOM();
}
if (req.flags & VM_REGION_TX)
xwrite(cd, (void *)req.vmr.addr, req.vmr.len);
ret = sys_madvise(req.vmr.addr, req.vmr.len, MADV_DONTNEED);
if (ret < 0) {
print_msg(2, "sys_madvise() MADV_DONTNEED of ");
print_msg(2, ulong_to_hstr((long)req.vmr.addr));
print_msg(2, " failed with ");
print_msg(2, long_to_str(ret));
print_msg(2, "\n");
}
}
return 0;
}
static int cmd_set_pages(int cd)
{
int ret;
struct vm_region_req req;
while (1) {
ret = xread(cd, &req, sizeof(req));
if (ret == 0)
break;
xread(cd, (void *)req.vmr.addr, req.vmr.len);
}
return 0;
}
static int cmd_end(int cd)
{
finish = 1;
return 0;
}
static int handle_connection(int cd)
{
int ret;
char cmd;
ret = sys_read(cd, &cmd, 1);
if (ret != 1) {
print_err(2, "sys_read() failed: ", ret);
return ret;
}
switch (cmd) {
case CMD_MPROTECT:
return cmd_mprotect(cd);
case CMD_GET_PAGES:
return cmd_get_pages(cd);
case CMD_SET_PAGES:
return cmd_set_pages(cd);
case CMD_END:
return cmd_end(cd);
default:
print_err(2, "unhandled cmd ", cmd);
break;
}
return 0;
}
void __attribute__((__used__)) service(unsigned int cmd, void *args)
{
int ret;
struct parasite_args *pa = args;
int srvd;
struct sockaddr_un addr;
srvd = sys_socket(PF_UNIX, SOCK_STREAM, 0);
if (srvd < 0) {
die("sys_socket() failed: ", srvd);
}
addr.sun_family = PF_UNIX;
xstrcpy(addr.sun_path, pa->addr);
if ('#' == addr.sun_path[0])
addr.sun_path[0] = '\0';
ret = sys_bind(srvd, (struct sockaddr *)&addr, sizeof(addr));
if (ret) {
die("sys_bind() failed: ", ret);
}
ret = sys_listen(srvd, 8);
if (ret < 0) {
die("sys_listen() failed: ", ret);
}
while (!finish) {
ret = sys_accept(srvd, NULL, NULL);
if (ret < 0) {
print_err(2, "sys_accept() failed: ", ret);
} else {
handle_connection(ret);
sys_close(ret);
}
}
sys_close(srvd);
sys_exit(0);
}