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tnt_syswrap.c
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/*--------------------------------------------------------------------*/
/*--- Wrappers for tainting syscalls ---*/
/*--- tnt_syswrap.c ---*/
/*--------------------------------------------------------------------*/
/*
This file is part of Taintgrind, a Valgrind tool for
tracking marked/tainted data through memory.
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; either version 2 of the
License, or (at your option) any later version.
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 program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307, USA.
The GNU General Public License is contained in the file COPYING.
*/
#include "pub_tool_basics.h"
#include "pub_tool_vki.h"
#include "pub_tool_vkiscnums.h"
#include "pub_tool_hashtable.h"
#include "pub_tool_tooliface.h"
#include "pub_tool_libcbase.h"
#include "pub_tool_libcassert.h"
#include "pub_tool_libcprint.h"
#include "pub_tool_libcproc.h"
#include "pub_tool_libcfile.h"
#include "pub_tool_machine.h"
#include "pub_tool_aspacemgr.h"
#include "pub_tool_threadstate.h"
#include "pub_tool_stacktrace.h" // for VG_(get_and_pp_StackTrace)
#include "pub_tool_debuginfo.h" // VG_(describe_IP), VG_(get_fnname)
#include "valgrind.h"
#include "tnt_include.h"
static
void resolve_filename(UWord fd, HChar *path, Int max)
{
HChar src[FD_MAX_PATH];
Int len = 0;
// TODO: Cache resolved fds by also catching open()s and close()s
VG_(sprintf)(src, "/proc/%d/fd/%d", VG_(getpid)(), (int)fd);
len = VG_(readlink)(src, path, max);
// Just give emptiness on error.
if (len == -1) len = 0;
path[len] = '\0';
}
/* enforce an arbitrary maximum */
static Bool tainted_fds[VG_N_THREADS][FD_MAX];
static UInt read_offset = 0;
void TNT_(syscall_llseek)(ThreadId tid, UWord* args, UInt nArgs,
SysRes res) {
// int _llseek(int fildes, ulong offset_high, ulong offset_low, loff_t *result,, uint whence);
Int fd = args[0];
ULong offset_high = args[1];
ULong offset_low = args[2];
UInt result = args[3];
UInt whence = args[4];
ULong offset;
Bool verbose = False;
if (fd >= FD_MAX || tainted_fds[tid][fd] == False)
return;
if ( verbose )
{
VG_(printf)("syscall _llseek %d %d ", tid, fd);
VG_(printf)("0x%x 0x%x 0x%x 0x%x\n", (UInt)offset_high, (UInt)offset_low, result, whence);
}
offset = (offset_high<<32) | offset_low;
if( whence == 0/*SEEK_SET*/ )
read_offset = 0 + (UInt)offset;
else if( whence == 1/*SEEK_CUR*/ )
read_offset += (UInt)offset;
else //if( whence == 2/*SEEK_END*/ )
tl_assert(0);
}
Bool TNT_(syscall_allowed_check)(ThreadId tid, int syscallno) {
if (IN_SANDBOX && IS_SYSCALL_ALLOWED(syscallno)) {
HChar fnname[FNNAME_MAX];
TNT_(get_fnname)(tid, fnname, FNNAME_MAX);
VG_(printf)("*** Sandbox performed system call %s (%d) in method %s, but it is not allowed to. ***\n", syscallnames[syscallno], syscallno, fnname);
VG_(get_and_pp_StackTrace)(tid, STACK_TRACE_SIZE);
VG_(printf)("\n");
return False;
}
return True;
}
static
void read_common ( UInt taint_offset, Int taint_len,
UInt curr_offset, Int curr_len,
HChar *data ) {
UWord addr;
Int len;
//Int i;
if( TNT_(clo_taint_all) ){
addr = (UWord)data;
len = curr_len;
}else
//VG_(printf)("curr_offset 0x%x\n", curr_offset);
//VG_(printf)("curr_len 0x%x\n", curr_len);
//VG_(printf)("tnt_offset 0x%x\n", taint_offset);
//VG_(printf)("tnt_len 0x%x\n", taint_len);
/* Here we determine what bytes to taint
We have 4 variables -
taint_offset Starting file offset to taint
taint_len Number of bytes to taint
curr_offset Starting file offset currently read
curr_len Number of bytes currently read
We have to deal with 4 cases: (= refers to the region to be tainted)
Case 1:
taint_len
taint_offset |-----------------|
curr_len
curr_offset |---=================---|
Case 2:
taint_len
taint_offset |-----------------------|
curr_len
curr_offset |---====================|
Case 3:
taint_len
taint_offset |----------------------|
curr_len
curr_offset |====================---|
Case 4:
taint_len
taint_offset |-----------------------|
curr_len
curr_offset |====================|
*/
if( taint_offset >= curr_offset &&
taint_offset <= curr_offset + curr_len ){
if( (taint_offset + taint_len) <= (curr_offset + curr_len) ){
// Case 1
addr = (UWord)(data + taint_offset - curr_offset);
len = taint_len;
}else{
// Case 2
addr = (UWord)(data + taint_offset - curr_offset);
len = curr_len - taint_offset + curr_offset;
}
}else if( ( ( taint_offset + taint_len ) >= curr_offset ) &&
( ( taint_offset + taint_len ) <= (curr_offset + curr_len ) ) ){
// Case 3
addr = (UWord)data;
len = taint_len - curr_offset + taint_offset;
}else if( ( taint_offset <= curr_offset ) &&
( taint_offset + taint_len ) >= ( curr_offset + curr_len ) ){
// Case 4
addr = (UWord)data;
len = curr_len;
}else{
return;
}
TNT_(make_mem_tainted)( addr, len );
//for( i=0; i<len; i++)
// VG_(printf)("taint_byte 0x%08lx 0x%02x\n", addr+i, *(Char *)(addr+i));
}
void TNT_(syscall_read)(ThreadId tid, UWord* args, UInt nArgs,
SysRes res) {
// ssize_t read(int fildes, void *buf, size_t nbyte);
Int fd = args[0];
HChar *data = (HChar *)args[1];
UInt curr_offset = read_offset;
Int curr_len = sr_Res(res);
UInt taint_offset = TNT_(clo_taint_start);
Int taint_len = TNT_(clo_taint_len);
Bool verbose = False;
TNT_(check_fd_access)(tid, fd, FD_READ);
if (curr_len == 0) return;
TNT_(make_mem_untainted)( (UWord)data, curr_len );
if (fd >= FD_MAX || tainted_fds[tid][fd] == False)
return;
if(verbose){
//VG_(printf)("taint_offset: 0x%x\ttaint_len: 0x%x\n", taint_offset, taint_len);
//VG_(printf)("curr_offset : 0x%x\tcurr_len : 0x%x\n", curr_offset, curr_len);
VG_(printf)("syscall read %d %d ", tid, fd);
#ifdef VGA_amd64
VG_(printf)("0x%x 0x%x 0x%llx 0x%x\n", curr_offset, curr_len, (ULong)data,
*(HChar *)data);
#else
VG_(printf)("0x%x 0x%x 0x%x 0x%x\n", curr_offset, curr_len, (UInt)data,
*(HChar *)data);
#endif
}
read_common ( taint_offset, taint_len, curr_offset, curr_len, data );
// Update file position
read_offset += curr_len;
// DEBUG
//tnt_read = 1;
}
void TNT_(syscall_pread)(ThreadId tid, UWord* args, UInt nArgs,
SysRes res) {
// ssize_t pread(int fildes, void *buf, size_t nbyte, size_t offset);
Int fd = args[0];
HChar *data = (HChar *)args[1];
UInt curr_offset = (Int)args[3];
Int curr_len = sr_Res(res);
UInt taint_offset = TNT_(clo_taint_start);
Int taint_len = TNT_(clo_taint_len);
Bool verbose = False;
if (curr_len == 0) return;
TNT_(make_mem_untainted)( (UWord)data, curr_len );
if (fd >= FD_MAX || tainted_fds[tid][fd] == False)
return;
if(verbose){
//VG_(printf)("taint_offset: 0x%x\ttaint_len: 0x%x\n", taint_offset, taint_len);
//VG_(printf)("curr_offset : 0x%x\tcurr_len : 0x%x\n", curr_offset, curr_len);
VG_(printf)("syscall pread %d %d ", tid, fd);
#ifdef VGA_amd64
VG_(printf)("0x%x 0x%x 0x%llx\n", curr_offset, curr_len, (ULong)data);
#else
VG_(printf)("0x%x 0x%x 0x%x\n", curr_offset, curr_len, (UInt)data);
#endif
}
read_common ( taint_offset, taint_len, curr_offset, curr_len, data );
}
void TNT_(syscall_open)(ThreadId tid, UWord* args, UInt nArgs, SysRes res) {
// int open (const char *filename, int flags[, mode_t mode])
HChar fdpath[FD_MAX_PATH];
Int fd = sr_Res(res);
Bool verbose = False;
// check if we have already created a sandbox
if (have_created_sandbox && !IN_SANDBOX) {
#ifdef VGO_freebsd
VG_(resolve_filename)(fd, fdpath, FD_MAX_PATH-1);
#elif defined VGO_linux
resolve_filename(fd, fdpath, FD_MAX_PATH-1);
#else
#error OS unknown
#endif
HChar fnname[FNNAME_MAX];
TNT_(get_fnname)(tid, fnname, FNNAME_MAX);
VG_(printf)("*** The file %s (fd: %d) was opened in method %s after a sandbox was created, hence it will not be accessible to the sandbox. It will need to be passed to the sandbox using sendmsg. ***\n", fdpath, fd, fnname);
VG_(get_and_pp_StackTrace)(tid, STACK_TRACE_SIZE);
VG_(printf)("\n");
}
// Nothing to do if no file tainting
if ( VG_(strlen)( TNT_(clo_file_filter)) == 0 )
return;
if (fd > -1 && fd < FD_MAX) {
#ifdef VGO_freebsd
VG_(resolve_filename)(fd, fdpath, FD_MAX_PATH-1);
#elif defined VGO_linux
resolve_filename(fd, fdpath, FD_MAX_PATH-1);
#else
#error OS unknown
#endif
if( TNT_(clo_taint_all) ){
tainted_fds[tid][fd] = True;
if ( verbose )
VG_(printf)("syscall open %d %s %lx %d\n", tid, fdpath, args[1], fd);
read_offset = 0;
} else if ( VG_(strncmp)(fdpath, TNT_(clo_file_filter),
VG_(strlen)( TNT_(clo_file_filter))) == 0 ) {
tainted_fds[tid][fd] = True;
if ( verbose )
VG_(printf)("syscall open %d %s %lx %d\n", tid, fdpath, args[1], fd);
read_offset = 0;
} else if ( TNT_(clo_file_filter)[0] == '*' &&
VG_(strncmp)( fdpath + VG_(strlen)(fdpath)
- VG_(strlen)( TNT_(clo_file_filter) ) + 1,
TNT_(clo_file_filter) + 1,
VG_(strlen)( TNT_(clo_file_filter)) - 1 ) == 0 ) {
tainted_fds[tid][fd] = True;
if ( verbose )
VG_(printf)("syscall open %d %s %lx %d\n", tid, fdpath, args[1], fd);
read_offset = 0;
} else
tainted_fds[tid][fd] = False;
}
}
void TNT_(syscall_close)(ThreadId tid, UWord* args, UInt nArgs, SysRes res) {
// int close (int filedes)
Int fd = args[0];
if (fd > -1 && fd < FD_MAX){
//if (tainted_fds[tid][fd] == True)
// VG_(printf)("syscall close %d %d\n", tid, fd);
shared_fds[fd] = 0;
tainted_fds[tid][fd] = False;
}
}
void TNT_(syscall_write)(ThreadId tid, UWord* args, UInt nArgs, SysRes res) {
Int fd = args[0];
TNT_(check_fd_access)(tid, fd, FD_WRITE);
}
void TNT_(get_fnname)(ThreadId tid, HChar* buf, UInt buf_size) {
UInt pc = VG_(get_IP)(tid);
VG_(get_fnname)(pc, buf, buf_size);
}
void TNT_(check_fd_access)(ThreadId tid, UInt fd, Int fd_request) {
if (IN_SANDBOX) {
Bool allowed = shared_fds[fd] & fd_request;
// VG_(printf)("checking if allowed to %s from fd %d ... %d\n", (fd_request == FD_READ ? "read" : "write"), fd, allowed);
if (!allowed) {
const HChar* access_str;
switch (fd_request) {
case FD_READ: {
access_str = "read from";
break;
}
case FD_WRITE: {
access_str = "wrote to";
break;
}
default: {
tl_assert(0);
break;
}
}
HChar fdpath[FD_MAX_PATH];
#ifdef VGO_freebsd
VG_(resolve_filename)(fd, fdpath, FD_MAX_PATH-1);
#elif defined VGO_linux
resolve_filename(fd, fdpath, FD_MAX_PATH-1);
#else
#error OS unknown
#endif
HChar fnname[FNNAME_MAX];
TNT_(get_fnname)(tid, fnname, FNNAME_MAX);
VG_(printf)("*** Sandbox %s %s (fd: %d) in method %s, but it is not allowed to. ***\n", access_str, fdpath, fd, fnname);
VG_(get_and_pp_StackTrace)(tid, STACK_TRACE_SIZE);
VG_(printf)("\n");
}
}
}
void TNT_(syscall_recv)(ThreadId tid, UWord* args, UInt nArgs, SysRes res) {
// ssize_t recv(int sockfd, void *buf, size_t len, int flags)
Int msglen = sr_Res(res);
HChar *data = (HChar *)args[1];
VG_(printf)("syscall recv %d 0x%x 0x%02x\n", tid, msglen, data[0]);
}
void TNT_(syscall_recvfrom)(ThreadId tid, UWord* args, UInt nArgs, SysRes res) {
// ssize_t recvfrom(int sockfd, void *buf, size_t len, int flags,
// struct sockaddr *src_addr, socklen_t *addrlen)
// TODO: #include <arpa/inet.h> inet_ntop to pretty print IP address
Int msglen = sr_Res(res);
HChar *data = (HChar *)args[1];
VG_(printf)("syscall recvfrom %d 0x%x 0x%02x\n", tid, msglen, data[0]);
}
/*--------------------------------------------------------------------*/
/*--- end ---*/
/*--------------------------------------------------------------------*/