usr.bin/truss/i386-linux.c

/*
 * Copryight 1997 Sean Eric Fagan
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by Sean Eric Fagan
 * 4. Neither the name of the author may be used to endorse or promote
 *    products derived from this software without specific prior written
 *    permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifndef lint
static const char rcsid[] =
  "$FreeBSD: head/usr.bin/truss/i386-linux.c 168569 2007-04-10 04:03:34Z delphij $";
#endif /* not lint */

/*
 * Linux/i386-specific system call handling.  Given how much of this code
 * is taken from the freebsd equivalent, I can probably put even more of
 * it in support routines that can be used by any personality support.
 */

#include <sys/types.h>
#include <sys/ptrace.h>

#include <machine/reg.h>
#include <machine/psl.h>

#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>

#include "truss.h"
#include "syscall.h"
#include "extern.h"

static int cpid = -1;

#include "linux_syscalls.h"

static int nsyscalls =
	sizeof(linux_syscallnames) / sizeof(linux_syscallnames[0]);

/*
 * This is what this particular file uses to keep track of a system call.
 * It is probably not quite sufficient -- I can probably use the same
 * structure for the various syscall personalities, and I also probably
 * need to nest system calls (for signal handlers).
 *
 * 'struct syscall' describes the system call; it may be NULL, however,
 * if we don't know about this particular system call yet.
 */
static struct linux_syscall {
	struct syscall *sc;
	const char *name;
	int number;
	unsigned long args[5];
	int nargs;	/* number of arguments -- *not* number of words! */
	char **s_args;	/* the printable arguments */
} fsc;

/* Clear up and free parts of the fsc structure. */
static __inline void
clear_fsc(void) {
  if (fsc.s_args) {
    int i;
    for (i = 0; i < fsc.nargs; i++)
      if (fsc.s_args[i])
	free(fsc.s_args[i]);
    free(fsc.s_args);
  }
  memset(&fsc, 0, sizeof(fsc));
}

/*
 * Called when a process has entered a system call.  nargs is the
 * number of words, not number of arguments (a necessary distinction
 * in some cases).  Note that if the STOPEVENT() code in i386/i386/trap.c
 * is ever changed these functions need to keep up.
 */

void
i386_linux_syscall_entry(struct trussinfo *trussinfo, int nargs) {
  struct reg regs;
  int syscall_num;
  int i;
  struct syscall *sc;

  cpid = trussinfo->curthread->tid;

  clear_fsc();

  if (ptrace(PT_GETREGS, cpid, (caddr_t)&regs, 0) < 0)
  {
    fprintf(trussinfo->outfile, "-- CANNOT READ REGISTERS --\n");
    return;
  }
  syscall_num = regs.r_eax;

  fsc.number = syscall_num;
  fsc.name =
    (syscall_num < 0 || syscall_num > nsyscalls) ? NULL : linux_syscallnames[syscall_num];
  if (!fsc.name) {
    fprintf(trussinfo->outfile, "-- UNKNOWN SYSCALL %d --\n", syscall_num);
  }

  if (fsc.name && (trussinfo->flags & FOLLOWFORKS)
   && ((!strcmp(fsc.name, "linux_fork")
    || !strcmp(fsc.name, "linux_vfork"))))
  {
    trussinfo->curthread->in_fork = 1;
  }

  if (nargs == 0)
    return;

  /*
   * Linux passes syscall arguments in registers, not
   * on the stack.  Fortunately, we've got access to the
   * register set.  Note that we don't bother checking the
   * number of arguments.  And what does linux do for syscalls
   * that have more than five arguments?
   */

  fsc.args[0] = regs.r_ebx;
  fsc.args[1] = regs.r_ecx;
  fsc.args[2] = regs.r_edx;
  fsc.args[3] = regs.r_esi;
  fsc.args[4] = regs.r_edi;

  sc = get_syscall(fsc.name);
  if (sc) {
    fsc.nargs = sc->nargs;
  } else {
#if DEBUG
    fprintf(trussinfo->outfile, "unknown syscall %s -- setting args to %d\n",
	   fsc.name, nargs);
#endif
    fsc.nargs = nargs;
  }

  fsc.s_args = malloc((1+fsc.nargs) * sizeof(char*));
  memset(fsc.s_args, 0, fsc.nargs * sizeof(char*));
  fsc.sc = sc;

  /*
   * At this point, we set up the system call arguments.
   * We ignore any OUT ones, however -- those are arguments that
   * are set by the system call, and so are probably meaningless
   * now.  This doesn't currently support arguments that are
   * passed in *and* out, however.
   */

  if (fsc.name) {

#if DEBUG
    fprintf(stderr, "syscall %s(", fsc.name);
#endif
    for (i = 0; i < fsc.nargs; i++) {
#if DEBUG
      fprintf(stderr, "0x%x%s",
	      sc
	      ? fsc.args[sc->args[i].offset]
	      : fsc.args[i],
	      i < (fsc.nargs - 1) ? "," : "");
#endif
      if (sc && !(sc->args[i].type & OUT)) {
	fsc.s_args[i] = print_arg(&sc->args[i], fsc.args, 0, trussinfo);
      }
    }
#if DEBUG
    fprintf(stderr, ")\n");
#endif
  }

#if DEBUG
  fprintf(trussinfo->outfile, "\n");
#endif

  /*
   * Some system calls should be printed out before they are done --
   * execve() and exit(), for example, never return.  Possibly change
   * this to work for any system call that doesn't have an OUT
   * parameter?
   */

  if (fsc.name != NULL &&
      (!strcmp(fsc.name, "execve") || !strcmp(fsc.name, "exit"))) {

    /* XXX
     * This could be done in a more general
     * manner but it still wouldn't be very pretty.
     */
    if (!strcmp(fsc.name, "linux_execve")) {
        if ((trussinfo->flags & EXECVEARGS) == 0)
          if (fsc.s_args[1]) {
            free(fsc.s_args[1]);
            fsc.s_args[1] = NULL;
          }
        if ((trussinfo->flags & EXECVEENVS) == 0)
          if (fsc.s_args[2]) {
            free(fsc.s_args[2]);
            fsc.s_args[2] = NULL;
          }
    }

    print_syscall(trussinfo, fsc.name, fsc.nargs, fsc.s_args);
    fprintf(trussinfo->outfile, "\n");
  }

  return;
}

/*
 * Linux syscalls return negative errno's, we do positive and map them
 */
const int bsd_to_linux_errno[] = {
  	-0,  -1,  -2,  -3,  -4,  -5,  -6,  -7,  -8,  -9,
 	-10, -35, -12, -13, -14, -15, -16, -17, -18, -19,
 	-20, -21, -22, -23, -24, -25, -26, -27, -28, -29,
 	-30, -31, -32, -33, -34, -11,-115,-114, -88, -89,
 	-90, -91, -92, -93, -94, -95, -96, -97, -98, -99,
	-100,-101,-102,-103,-104,-105,-106,-107,-108,-109,
	-110,-111, -40, -36,-112,-113, -39, -11, -87,-122,
	-116, -66,  -6,  -6,  -6,  -6,  -6, -37, -38,  -9,
  	-6,
};

long
i386_linux_syscall_exit(struct trussinfo *trussinfo, int syscall_num __unused)
{
  struct reg regs;
  long retval;
  int i;
  int errorp;
  struct syscall *sc;

  cpid = trussinfo->curthread->tid;
  if (ptrace(PT_GETREGS, cpid, (caddr_t)&regs, 0) < 0)
  {
    fprintf(trussinfo->outfile, "-- CANNOT READ REGISTERS --\n");
    return (-1);
  }

  retval = regs.r_eax;
  errorp = !!(regs.r_eflags & PSL_C);

  /*
   * This code, while simpler than the initial versions I used, could
   * stand some significant cleaning.
   */

  sc = fsc.sc;
  if (!sc) {
    for (i = 0; i < fsc.nargs; i++)
      asprintf(&fsc.s_args[i], "0x%lx", fsc.args[i]);
  } else {
    /*
     * Here, we only look for arguments that have OUT masked in --
     * otherwise, they were handled in the syscall_entry function.
     */
    for (i = 0; i < sc->nargs; i++) {
      char *temp;
      if (sc->args[i].type & OUT) {
	/*
	 * If an error occurred, than don't bothe getting the data;
	 * it may not be valid.
	 */
	if (errorp)
	  asprintf(&temp, "0x%lx", fsc.args[sc->args[i].offset]);
	else
	  temp = print_arg(&sc->args[i], fsc.args, retval, trussinfo);
	fsc.s_args[i] = temp;
      }
    }
  }

  /*
   * It would probably be a good idea to merge the error handling,
   * but that complicates things considerably.
   */
  if (errorp) {
    for (i = 0; (size_t)i < sizeof(bsd_to_linux_errno) / sizeof(int); i++)
      if (retval == bsd_to_linux_errno[i])
      break;
  }
  print_syscall_ret(trussinfo, fsc.name, fsc.nargs, fsc.s_args, errorp,
                    errorp ? i : retval);
  clear_fsc();

  return (retval);
}