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/*
* assfault.so, 2001-09-25, anonymous@segfault.net
*
* This is unpublished proprietary source code of someone without a name...
* someone who dont need to be named....
*
* The contents of these coded instructions, statements and computer
* programs may not be disclosed to third parties, copied or duplicated in
* any form, in whole or in part, without the prior written permission of
* the author.
*
* Tries to catch SIGSEGV/SIGILL and continues execution flow.
*
* $ make
* $ LD_PRELOAD=./assfault.so netscape &
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <dlfcn.h>
#define REPLACE(a, x, y) if ( !(o_##x = dlsym(##a , ##y)) )\
{ fprintf(stderr, ##y"() not found in libc!\n");\
exit(-1); }
static void *(*o_signal)(int, void(*)(int));
static void *libc_handle = NULL;
static int segillcount = 0;
void
assfault_handler(int sig)
{
fprintf(stderr, "%s occured (%d)\n"
, (sig==SIGSEGV)?"SIGSEGV":"SIGILL", ++segillcount);
asm("
movl 0x44(%ebp),%ebx
incl %ebx
movl %ebx,0x44(%ebp)
");
}
/*
* you may want to intercept sigprocmask, sigaction, setsig, .. also
*/
void
(*signal(int signum, void (*sighandler)(int)))(int)
{
/*
* ignore if programm tries to set signal handler for SIGSEGV/SIGILL
*/
if (signum == SIGSEGV)
{
fprintf(stderr, "signal(SIGSEGV, ...) call ignored [%d]\n", getpid());
return assfault_handler;
}
if (signum == SIGILL)
{
fprintf(stderr, "signal(SIGSILL, ...) call ignored [%d]\n", getpid());
return assfault_handler;
}
/*
* call the original libc signal() -function
*/
return o_signal(signum, sighandler);
}
static void
assfault_init(void)
{
if ( (libc_handle = dlopen("libc.so", RTLD_NOW)) == NULL)
if ( (libc_handle = dlopen("libc.so.6", RTLD_NOW)) == NULL)
{
fprintf(stderr, "error loading libc!\n");
exit(-1);
}
REPLACE(libc_handle, signal, "signal");
o_signal(SIGSEGV, assfault_handler);
o_signal(SIGILL, assfault_handler);
dlclose(libc_handle);
}
/*
* this function is called by the loaded.
*/
void
_init(void)
{
if (libc_handle != NULL)
return; /* should never happen */
fprintf(stderr, "assfault.so activated\n");
assfault_init();
}
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