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Date:      Thu, 29 Mar 2012 18:45:43 +0530
From:      Maninya M <maninya@gmail.com>
To:        freebsd-hackers@freebsd.org, John Baldwin <jhb@freebsd.org>,  Julian Elischer <julian@freebsd.org>
Subject:   Re: __NR_mmap2 in FreeBSD
Message-ID:  <CAC46K3kvymco4bDu0RJND64ejpWyPth8qFCOEx=gY9BbPGYSLg@mail.gmail.com>
In-Reply-To: <201203270753.21534.jhb@freebsd.org>
References:  <CAC46K3kjQyqQ0VvjP%2BUwQkSooqbT1HR=SVYUpz8KQ1CcYovaEA@mail.gmail.com> <201203270753.21534.jhb@freebsd.org>
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Thanks a lot for replying!
Ok I've tried this to push arguments onto stack.
Is it right?
I get an error at this line:

   die_perror("ptrace(PT_WRITE,%d,0x%.8x,INT 0x80) failed while
dasfallocating memory",exec_pid,temp_regs.r_eip);


Please tell me what to do.





void map_memory(unsigned long addr, unsigned long size, int flags)
{
  int status;
  struct reg regs,temp_regs;
  unsigned long int_instr = 0x000080cd; /* INT 0x80 */

  if (ptrace(PT_GETREGS,exec_pid,(caddr_t)&regs,0) < 0)
    die_perror("ptrace(PTRACE_GETREGS,%d,(caddr_t)&regs,0)",exec_pid);

  /* mmap2 system call seems to take arguments as follows:
   * eax = __NR_mmap2
   * ebx = (unsigned long) page aligned address
   * ecx = (unsigned long) page aligned file size
   * edx = protection
   * esi = flags
   * Other arguments (fd and pgoff) are not required for anonymous mapping
   */
  temp_regs = regs;

//printf("temp=%u,\teip=%u\tregs=%u\teip=%u\n",&temp_regs,temp_regs.r_eip,&regs,regs.r_eip);
 // temp_regs.r_eax = __NR_mmap2;
 temp_regs.r_eax=71;
  /*temp_regs.r_ebx = addr;
  temp_regs.r_ecx = size;
  temp_regs.r_edx = flags;
  temp_regs.r_esi = MAP_PRIVATE | MAP_ANONYMOUS;*/
  //push size

 //temp_regs.r_eip = temp_regs.r_esp - 4;

//printf("temp=%u,\teip=%u\tregs=%u\teip=%u\n",&temp_regs,temp_regs.r_eip,&regs,regs.r_eip);
if (ptrace(PT_WRITE_D,exec_pid,(void *)(temp_regs.r_esp-4),MAP_PRIVATE |
MAP_ANONYMOUS) < 0)
    die_perror("ptrace(PT_WRITE,%d,0x%.8x,INT 0x80) failed while allocating
memory",exec_pid,temp_regs.r_eip);

if (ptrace(PT_WRITE_D,exec_pid,(void *)(temp_regs.r_esp-8),flags) < 0)
    die_perror("ptrace(PT_WRITE,%d,0x%.8x,INT 0x80) failed while allocating
memory",exec_pid,temp_regs.r_eip);

if (ptrace(PT_WRITE_D,exec_pid,(void *)(temp_regs.r_esp-12),size) < 0)
    die_perror("ptrace(PT_WRITE,%d,0x%.8x,INT 0x80) failed while allocating
memory",exec_pid,temp_regs.r_eip);

if (ptrace(PT_WRITE_D,exec_pid,(void *)(temp_regs.r_esp-16), addr) < 0);
    die_perror("ptrace(PT_WRITE,%d,0x%.8x,INT 0x80) failed while
dasfallocating memory",exec_pid,temp_regs.r_eip);
/*
if (ptrace(PT_WRITE_I,exec_pid,(void *)(temp_regs.r_eip),0x000080cd) < 0)
    die_perror("ptrace(PT_WRITE,%d,0x%.8x,INT 0x80) failed while allocating
memory",exec_pid,temp_regs.r_eip);
*/
  if (ptrace(PT_WRITE_I,exec_pid,(void *)(temp_regs.r_eip),0x000080cd) < 0)
    die_perror("ptrace(PT_WRITE,%d,0x%.8x,INT 0x80) failed while allocating
memory",exec_pid,temp_regs.r_eip);
  if (ptrace(PT_SETREGS,exec_pid,(caddr_t)&temp_regs,0) < 0) {
    die_perror("ptrace(PT_SETREGS,%d,...) failed while allocating
memory",exec_pid);
  }
  if (ptrace(PT_STEP,exec_pid,NULL,0) < 0)
    die_perror("ptrace(PT_STEP,...) failed while executing mmap2");

  wait(&status);
  if (WIFEXITED(status))
    die("Restarted process abrubtly (exited with value %d). Aborting
Restart.",WEXITSTATUS(status));
  else if (WIFSIGNALED(status))
    die("Restarted process abrubtly exited because of uncaught signal (%d).
Aborting Restart.",WTERMSIG(status));

  if (ptrace(PT_GETREGS,exec_pid,(caddr_t)&temp_regs,0) < 0) {
    die_perror("ptrace(PT_GETREGS,...) failed after executing mmap2 system
call");
  }
//fprintf(stdout,"hello iam here \n");
  if (temp_regs.r_eax != addr)
    warn("Wanted space at address 0x%.8x, mmap2 system call returned
0x%.8x. This could be a problem.",addr,temp_regs.r_eax);
  else if (cr_options.verbose)

    fprintf(stdout,"Successfully allocated [0x%.8lx -
0x%.8lx]\n",addr,addr+size);

  /* Restore original registers */
  if (ptrace(PT_SETREGS,exec_pid,(caddr_t)&temp_regs,0) < 0) {
    die_perror("ptrace(PT_SETREGS,...) when restoring registering after
allocating memory (mmap2)");

  }
}






On 27 March 2012 17:23, John Baldwin <jhb@freebsd.org> wrote:

> On Monday, March 26, 2012 1:56:08 pm Maninya M wrote:
> > I am trying to convert a function written for Linux to FreeBSD.
> > What is the equivalent of the __NR_mmap2 system call in FreeBSD?
> >
> > I keep getting the error because of this exception:
> > warn("Wanted space at address 0x%.8x, mmap2 system call returned 0x%.8x.
> > This could be a problem.",addr,temp_regs.eax);
>
> I think you could just use plain mmap() for this?
>
> However, it seems that this is injecting a call into an existing binary,
> not calling mmap() directly.  A few things will need to change.  First,
> FreeBSD system calls on i386 put their arguments on the stack, not in
> registers, so you will need to do a bit more work to push the arguments
> onto
> the stack rather than just setting registers.
>
> > I changed
> > temp_regs.eax = __NR_mmap2;
> > to
> > temp_regs.eax = 192;
> >
> > but it didn't work. I suppose I couldn't understand this function. Please
> > help.
> >
> > This is the function:
> >
> > void map_memory(unsigned long addr, unsigned long size, int flags)
> > {
> >   int status;
> >   struct user_regs_struct regs,temp_regs;
> >   unsigned long int_instr = 0x000080cd; /* INT 0x80 */
> >
> >   if (ptrace(PTRACE_GETREGS,exec_pid,NULL,&regs) < 0)
> >     die_perror("ptrace(PTRACE_GETREGS,%d,NULL,&regs)",exec_pid);
> >
> >   /* mmap2 system call seems to take arguments as follows:
> >    * eax = __NR_mmap2
> >    * ebx = (unsigned long) page aligned address
> >    * ecx = (unsigned long) page aligned file size
> >    * edx = protection
> >    * esi = flags
> >    * Other arguments (fd and pgoff) are not required for anonymous
> mapping
> >    */
> >   temp_regs = regs;
> >   temp_regs.eax = __NR_mmap2;
> >   temp_regs.ebx = addr;
> >   temp_regs.ecx = size;
> >   temp_regs.edx = flags;
> >   temp_regs.esi = MAP_PRIVATE | MAP_ANONYMOUS;
> >   temp_regs.eip = temp_regs.esp - 4;
> >
> >   if (ptrace(PTRACE_POKETEXT,exec_pid,(void
> > *)(temp_regs.eip),(void*)int_instr) < 0)
> >     die_perror("ptrace(PTRACE_POKETEXT,%d,0x%.8x,INT 0x80) failed while
> > allocating memory",exec_pid,temp_regs.eip);
> >   if (ptrace(PTRACE_SETREGS,exec_pid,NULL,&temp_regs) < 0) {
> >     die_perror("ptrace(PTRACE_SETREGS,%d,...) failed while allocating
> > memory",exec_pid);
> >   }
> >   if (ptrace(PTRACE_SINGLESTEP,exec_pid,NULL,NULL) < 0)
> >     die_perror("ptrace(PTRACE_SINGLESTEP,...) failed while executing
> > mmap2");
> >
> >   wait(&status);
> >   if (WIFEXITED(status))
> >     die("Restarted process abrubtly (exited with value %d). Aborting
> > Restart.",WEXITSTATUS(status));
> >   else if (WIFSIGNALED(status))
> >     die("Restarted process abrubtly exited because of uncaught signal
> (%d).
> > Aborting Restart.",WTERMSIG(status));
> >
> >   if (ptrace(PTRACE_GETREGS,exec_pid,NULL,&temp_regs) < 0) {
> >     die_perror("ptrace(PTRACE_GETREGS,...) failed after executing mmap2
> > system call");
> >   }
> >
> >   if (temp_regs.eax != addr)
> >     warn("Wanted space at address 0x%.8x, mmap2 system call returned
> > 0x%.8x. This could be a problem.",addr,temp_regs.eax);
> >   else if (cr_options.verbose)
> >     fprintf(stdout,"Successfully allocated [0x%.8lx -
> > 0x%.8lx]\n",addr,addr+size);
> >
> >   /* Restore original registers */
> >   if (ptrace(PTRACE_SETREGS,exec_pid,NULL,&regs) < 0) {
> >     die_perror("ptrace(PTRACE_SETREGS,...) when restoring registering
> after
> > allocating memory (mmap2)");
> >   }
> > }
> >
> > --
> > Maninya
> > _______________________________________________
> > freebsd-hackers@freebsd.org mailing list
> > http://lists.freebsd.org/mailman/listinfo/freebsd-hackers
> > To unsubscribe, send any mail to "
> freebsd-hackers-unsubscribe@freebsd.org"
> >
>
> --
> John Baldwin
>



-- 
Maninya

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