[apple/xnu.git] / bsd / kern / kern_exec.c

/*
 * Copyright (c) 2006 Apple Computer, Inc. All Rights Reserved.
 * 
 * @APPLE_LICENSE_OSREFERENCE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code 
 * as defined in and that are subject to the Apple Public Source License 
 * Version 2.0 (the 'License'). You may not use this file except in 
 * compliance with the License.  The rights granted to you under the 
 * License may not be used to create, or enable the creation or 
 * redistribution of, unlawful or unlicensed copies of an Apple operating 
 * system, or to circumvent, violate, or enable the circumvention or 
 * violation of, any terms of an Apple operating system software license 
 * agreement.
 *
 * Please obtain a copy of the License at 
 * http://www.opensource.apple.com/apsl/ and read it before using this 
 * file.
 *
 * The Original Code and all software distributed under the License are 
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER 
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, 
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, 
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. 
 * Please see the License for the specific language governing rights and 
 * limitations under the License.
 *
 * @APPLE_LICENSE_OSREFERENCE_HEADER_END@
 */
/* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
/*
 * Mach Operating System
 * Copyright (c) 1987 Carnegie-Mellon University
 * All rights reserved.  The CMU software License Agreement specifies
 * the terms and conditions for use and redistribution.
 */
 
#include <cputypes.h>

/*-
 * Copyright (c) 1982, 1986, 1991, 1993
 *      The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * 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 the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 *
 *      from: @(#)kern_exec.c   8.1 (Berkeley) 6/10/93
 */
#include <machine/reg.h>

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/filedesc.h>
#include <sys/kernel.h>
#include <sys/proc_internal.h>
#include <sys/kauth.h>
#include <sys/user.h>
#include <sys/socketvar.h>
#include <sys/malloc.h>
#include <sys/namei.h>
#include <sys/mount_internal.h>
#include <sys/vnode_internal.h>         
#include <sys/file_internal.h>
#include <sys/stat.h>
#include <sys/uio_internal.h>
#include <sys/acct.h>
#include <sys/exec.h>
#include <sys/kdebug.h>
#include <sys/signal.h>
#include <sys/aio_kern.h>
#include <sys/sysproto.h>
#include <sys/shm_internal.h>           /* shmexec() */
#include <sys/ubc_internal.h>           /* ubc_map() */

#include <bsm/audit_kernel.h>

#include <mach/mach_types.h>
#include <mach/task.h>
#include <mach/thread_act.h>
#include <mach/vm_map.h>
#include <mach/mach_vm.h>
#include <mach/vm_param.h>

#include <vm/vm_map.h>
#include <vm/vm_kern.h>
#include <vm/vm_pager.h>
#include <vm/vm_kern.h>
#include <vm/task_working_set.h>
#include <vm/vm_shared_memory_server.h>

/*
 * Mach things for which prototypes are unavailable from Mach headers
 */
void            ipc_task_reset(
                        task_t          task);

extern struct savearea *get_user_regs(thread_t);


#include <kern/thread.h>
#include <kern/task.h>
#include <kern/ast.h>
#include <kern/mach_loader.h>
#include <mach-o/fat.h>
#include <mach-o/loader.h>
#include <machine/vmparam.h>
#if KTRACE   
#include <sys/ktrace.h>
#endif
#include <sys/imgact.h>


/*
 * SIZE_MAXPTR          The maximum size of a user space pointer, in bytes
 * SIZE_IMG_STRSPACE    The available string space, minus two pointers; we
 *                      define it interms of the maximum, since we don't
 *                      know the pointer size going in, until after we've
 *                      parsed the executable image.
 */
#define SIZE_MAXPTR             8                               /* 64 bits */
#define SIZE_IMG_STRSPACE       (NCARGS - 2 * SIZE_MAXPTR)

int     app_profile = 0;

extern vm_map_t bsd_pageable_map;
extern struct fileops vnops;

#define ROUND_PTR(type, addr)   \
        (type *)( ( (unsigned)(addr) + 16 - 1) \
                  & ~(16 - 1) )

struct image_params;    /* Forward */
static int exec_copyout_strings(struct image_params *imgp, user_addr_t *stackp);
static int load_return_to_errno(load_return_t lrtn);
static int execargs_alloc(struct image_params *imgp);
static int execargs_free(struct image_params *imgp);
static int exec_check_permissions(struct image_params *imgp);
static int exec_extract_strings(struct image_params *imgp);
static int exec_handle_sugid(struct image_params *imgp);
static int sugid_scripts = 0;
SYSCTL_INT (_kern, OID_AUTO, sugid_scripts, CTLFLAG_RW, &sugid_scripts, 0, "");
static kern_return_t create_unix_stack(vm_map_t map, user_addr_t user_stack,
                                        int customstack, struct proc *p);
static int copyoutptr(user_addr_t ua, user_addr_t ptr, int ptr_size);

/* XXX forward; should be in headers, but can't be for one reason or another */
extern int grade_binary(cpu_type_t exectype, cpu_subtype_t execsubtype);
extern void vfork_return(thread_t th_act,
                                struct proc * p,
                                struct proc *p2,
                                register_t *retval);


extern char classichandler[32];
extern uint32_t classichandler_fsid;
extern long classichandler_fileid;


/*
 * exec_add_string
 *
 * Add the requested string to the string space area.
 *
 * Parameters;  struct image_params *           image parameter block
 *              user_addr_t                     string to add to strings area
 *              uio_seg                         segment where string is located
 *
 * Returns:     0                       Success
 *              !0                      Failure errno from copyinstr()
 *
 * Implicit returns:
 *              (imgp->ip_strendp)      updated location of next add, if any
 *              (imgp->ip_strspace)     updated byte count of space remaining
 */
static int
exec_add_string(struct image_params *imgp, user_addr_t str, /*uio_seg*/int seg)
{
        int error = 0;

        do {
                size_t len = 0;
                if (imgp->ip_strspace <= 0) {
                        error = E2BIG;
                        break;
                }
                if (IS_UIO_SYS_SPACE(seg)) {
                        char *kstr = CAST_DOWN(char *,str);     /* SAFE */
                        error = copystr(kstr, imgp->ip_strendp, imgp->ip_strspace, &len);
                } else  {
                        error = copyinstr(str, imgp->ip_strendp, imgp->ip_strspace,
                            &len);
                }
                imgp->ip_strendp += len;
                imgp->ip_strspace -= len;
        } while (error == ENAMETOOLONG);

        return error;
}

/*
 * exec_save_path
 *
 * To support new app package launching for Mac OS X, the dyld needs the
 * first argument to execve() stored on the user stack.
 *
 * Save the executable path name at the top of the strings area and set
 * the argument vector pointer to the location following that to indicate
 * the start of the argument and environment tuples, setting the remaining
 * string space count to the size of the string area minus the path length
 * and a reserve for two pointers.
 *
 * Parameters;  struct image_params *           image parameter block
 *              char *                          path used to invoke program
 *              uio_seg                         segment where path is located
 *
 * Returns:     int                     0       Success
 *                                      !0      Failure: error number
 * Implicit returns:
 *              (imgp->ip_strings)              saved path
 *              (imgp->ip_strspace)             space remaining in ip_strings
 *              (imgp->ip_argv)                 beginning of argument list
 *              (imgp->ip_strendp)              start of remaining copy area
 *
 * Note:        We have to do this before the initial namei() since in the
 *              path contains symbolic links, namei() will overwrite the
 *              original path buffer contents.  If the last symbolic link
 *              resolved was a relative pathname, we would lose the original
 *              "path", which could be an absolute pathname. This might be
 *              unacceptable for dyld.
 */
static int
exec_save_path(struct image_params *imgp, user_addr_t path, /*uio_seg*/int seg)
{
        int error;
        size_t  len;
        char *kpath = CAST_DOWN(char *,path);   /* SAFE */

        imgp->ip_strendp = imgp->ip_strings;
        imgp->ip_strspace = SIZE_IMG_STRSPACE;

        len = MIN(MAXPATHLEN, imgp->ip_strspace);

        switch( seg) {
        case UIO_USERSPACE32:
        case UIO_USERSPACE64:   /* Same for copyin()... */
                error = copyinstr(path, imgp->ip_strings, len, &len);
                break;
        case UIO_SYSSPACE32:
                error = copystr(kpath, imgp->ip_strings, len, &len);
                break;
        default:
                error = EFAULT;
                break;
        }

        if (!error) {
                imgp->ip_strendp += len;
                imgp->ip_strspace -= len;
                imgp->ip_argv = imgp->ip_strendp;
        }

        return(error);
}



/*
 * exec_shell_imgact
 *
 * Image activator for interpreter scripts.  If the image begins with the
 * characters "#!", then it is an interpreter script.  Verify that we are
 * not already executing in Classic mode, and that the length of the script
 * line indicating the interpreter is not in excess of the maximum allowed
 * size.  If this is the case, then break out the arguments, if any, which
 * are separated by white space, and copy them into the argument save area
 * as if they were provided on the command line before all other arguments.
 * The line ends when we encounter a comment character ('#') or newline.
 *
 * Parameters;  struct image_params *   image parameter block
 *
 * Returns:     -1                      not an interpreter (keep looking)
 *              -3                      Success: interpreter: relookup
 *              >0                      Failure: interpreter: error number
 *
 * A return value other than -1 indicates subsequent image activators should
 * not be given the opportunity to attempt to activate the image.
 */
static int
exec_shell_imgact(struct image_params *imgp)
{
        char *vdata = imgp->ip_vdata;
        char *ihp;
        char *line_endp;
        char *interp;

        /*
         * Make sure it's a shell script.  If we've already redirected
         * from an interpreted file once, don't do it again.
         *
         * Note: We disallow Classic, since the expectation is that we
         * may run a Classic interpreter, but not an interpret a Classic
         * image.  This is consistent with historical behaviour.
         */
        if (vdata[0] != '#' ||
            vdata[1] != '!' ||
            (imgp->ip_flags & IMGPF_INTERPRET) != 0) {
                return (-1);
        }


        imgp->ip_flags |= IMGPF_INTERPRET;

        /* Check to see if SUGID scripts are permitted.  If they aren't then
         * clear the SUGID bits.
         * imgp->ip_vattr is known to be valid.
         */
        if (sugid_scripts == 0) {
           imgp->ip_origvattr->va_mode &= ~(VSUID | VSGID);
        }

        /* Find the nominal end of the interpreter line */
        for( ihp = &vdata[2]; *ihp != '\n' && *ihp != '#'; ihp++) {
                if (ihp >= &vdata[IMG_SHSIZE])
                        return (ENOEXEC);
        }

        line_endp = ihp;
        ihp = &vdata[2];
        /* Skip over leading spaces - until the interpreter name */
        while ( ihp < line_endp && ((*ihp == ' ') || (*ihp == '\t')))
                ihp++;

        /*
         * Find the last non-whitespace character before the end of line or
         * the beginning of a comment; this is our new end of line.
         */
        for (;line_endp > ihp && ((*line_endp == ' ') || (*line_endp == '\t')); line_endp--)
                continue;

        /* Empty? */
        if (line_endp == ihp)
                return (ENOEXEC);

        /* copy the interpreter name */
        interp = imgp->ip_interp_name;
        while ((ihp < line_endp) && (*ihp != ' ') && (*ihp != '\t'))
                *interp++ = *ihp++;
        *interp = '\0';

        exec_save_path(imgp, CAST_USER_ADDR_T(imgp->ip_interp_name),
                                                        UIO_SYSSPACE32);

        ihp = &vdata[2];
        while (ihp < line_endp) {
                /* Skip leading whitespace before each argument */
                while ((*ihp == ' ') || (*ihp == '\t'))
                        ihp++;

                if (ihp >= line_endp)
                        break;

                /* We have an argument; copy it */
                while ((ihp < line_endp) && (*ihp != ' ') && (*ihp != '\t')) {  
                        *imgp->ip_strendp++ = *ihp++;
                        imgp->ip_strspace--;
                }
                *imgp->ip_strendp++ = 0;
                imgp->ip_strspace--;
                imgp->ip_argc++;
        }

        return (-3);
}



/*
 * exec_fat_imgact
 *
 * Image activator for fat 1.0 binaries.  If the binary is fat, then we
 * need to select an image from it internally, and make that the image
 * we are going to attempt to execute.  At present, this consists of
 * reloading the first page for the image with a first page from the
 * offset location indicated by the fat header.
 *
 * Important:   This image activator is byte order neutral.
 *
 * Note:        If we find an encapsulated binary, we make no assertions
 *              about its  validity; instead, we leave that up to a rescan
 *              for an activator to claim it, and, if it is claimed by one,
 *              that activator is responsible for determining validity.
 */
static int
exec_fat_imgact(struct image_params *imgp)
{
        struct proc *p = vfs_context_proc(imgp->ip_vfs_context);
        kauth_cred_t cred = p->p_ucred;
        struct fat_header *fat_header = (struct fat_header *)imgp->ip_vdata;
        struct fat_arch fat_arch;
        int resid, error;
        load_return_t lret;

        /* Make sure it's a fat binary */
        if ((fat_header->magic != FAT_MAGIC) &&
            (fat_header->magic != FAT_CIGAM)) {
                error = -1;
                goto bad;
        }

        /* Look up our preferred architecture in the fat file. */
        lret = fatfile_getarch_affinity(imgp->ip_vp,
                                        (vm_offset_t)fat_header,
                                        &fat_arch,
                                        (p->p_flag & P_AFFINITY));
        if (lret != LOAD_SUCCESS) {
                error = load_return_to_errno(lret);
                goto bad;
        }

        /* Read the Mach-O header out of it */
        error = vn_rdwr(UIO_READ, imgp->ip_vp, imgp->ip_vdata,
                        PAGE_SIZE, fat_arch.offset,
                        UIO_SYSSPACE32, (IO_UNIT|IO_NODELOCKED),
                        cred, &resid, p);
        if (error) {
                goto bad;
        }

        /* Did we read a complete header? */
        if (resid) {
                error = EBADEXEC;
                goto bad;
        }

        /* Success.  Indicate we have identified an encapsulated binary */
        error = -2;
        imgp->ip_arch_offset = (user_size_t)fat_arch.offset;
        imgp->ip_arch_size = (user_size_t)fat_arch.size;

bad:
        return (error);
}

/*
 * exec_mach_imgact
 *
 * Image activator for mach-o 1.0 binaries.
 *
 * Important:   This image activator is NOT byte order neutral.
 */
static int
exec_mach_imgact(struct image_params *imgp)
{
        struct mach_header *mach_header = (struct mach_header *)imgp->ip_vdata;
        kauth_cred_t            cred = vfs_context_ucred(imgp->ip_vfs_context);
        struct proc             *p = vfs_context_proc(imgp->ip_vfs_context);
        int                     error = 0;
        int                     vfexec = 0;
        task_t                  task;
        task_t                  new_task;
        thread_t                thread;
        struct uthread          *uthread;
        vm_map_t old_map = VM_MAP_NULL;
        vm_map_t map;
        boolean_t                               clean_regions = FALSE;
    shared_region_mapping_t initial_region = NULL;
        load_return_t           lret;
        load_result_t           load_result;
                
        /*
         * make sure it's a Mach-O 1.0 or Mach-O 2.0 binary; the difference
         * is a reserved field on the end, so for the most part, we can
         * treat them as if they were identical.
         */
        if ((mach_header->magic != MH_MAGIC) &&
            (mach_header->magic != MH_MAGIC_64)) {
        error = -1;
                goto bad;
        }

        task = current_task();
        thread = current_thread();
        uthread = get_bsdthread_info(thread);

        if (uthread->uu_flag & UT_VFORK)
                vfexec = 1;      /* Mark in exec */

        if ((mach_header->cputype & CPU_ARCH_ABI64) == CPU_ARCH_ABI64)
                imgp->ip_flags |= IMGPF_IS_64BIT;

        if (!grade_binary(mach_header->cputype, mach_header->cpusubtype)) {
                error = EBADARCH;
                goto bad;
        }

        /*
         * Copy in arguments/environment from the old process, if the
         * vector is non-NULL (i.e. exec is not being called from
         * load_init_program(), as a special case, at system startup).
         */
        if (imgp->ip_user_argv != 0LL) {
                error = exec_extract_strings(imgp);
                if (error)
                        goto bad;
        }

        /*
         * Hack for binary compatability; put three NULs on the end of the
         * string area, and round it up to the next word boundary.  This
         * ensures padding with NULs to the boundary.
         */
        imgp->ip_strendp[0] = 0;
        imgp->ip_strendp[1] = 0;
        imgp->ip_strendp[2] = 0;
        imgp->ip_strendp += (((imgp->ip_strendp - imgp->ip_strings) + NBPW-1) & ~(NBPW-1));


        if (vfexec) {
                kern_return_t   result;

                result = task_create_internal(task, FALSE, &new_task);
                if (result != KERN_SUCCESS)
                printf("execve: task_create failed. Code: 0x%x\n", result);
                p->task = new_task;
                set_bsdtask_info(new_task, p);
                if (p->p_nice != 0)
                        resetpriority(p);
                map = get_task_map(new_task);
                result = thread_create(new_task, &imgp->ip_vfork_thread);
                if (result != KERN_SUCCESS)
                printf("execve: thread_create failed. Code: 0x%x\n", result);
                /* reset local idea of task, thread, uthread */
                task = new_task;
                thread = imgp->ip_vfork_thread;
                uthread = get_bsdthread_info(thread);
        } else {
                map = VM_MAP_NULL;
        }

        /*
         * We set these flags here; this is OK, since if we fail after
         * this point, we have already destroyed the parent process anyway.
         */
        if (imgp->ip_flags & IMGPF_IS_64BIT) {
                task_set_64bit(task, TRUE);
                p->p_flag |= P_LP64;
        } else {
                task_set_64bit(task, FALSE);
                p->p_flag &= ~P_LP64;
        }

        /*
         *      Load the Mach-O file.
         */
/* LP64 - remove following "if" statement after osfmk/vm/task_working_set.c */
if((imgp->ip_flags & IMGPF_IS_64BIT) == 0)
        if(imgp->ip_tws_cache_name) {
                tws_handle_startup_file(task, kauth_cred_getuid(cred), 
                        imgp->ip_tws_cache_name, imgp->ip_vp, &clean_regions);
        }

        vm_get_shared_region(task, &initial_region);

        
        /*
         * NOTE: An error after this point  indicates we have potentially
         * destroyed or overwrote some process state while attempting an
         * execve() following a vfork(), which is an unrecoverable condition.
         */

        /*
         * We reset the task to 64-bit (or not) here.  It may have picked up
         * a new map, and we need that to reflect its true 64-bit nature.
         */
        task_set_64bit(task, 
                       ((imgp->ip_flags & IMGPF_IS_64BIT) == IMGPF_IS_64BIT));

        /*
         * Actually load the image file we previously decided to load.
         */
        lret = load_machfile(imgp, mach_header, thread, map, clean_regions, &load_result);

        if (lret != LOAD_SUCCESS) {
                error = load_return_to_errno(lret);
                goto badtoolate;
        }

        /* load_machfile() maps the vnode */
        (void)ubc_map(imgp->ip_vp, PROT_EXEC);

        /*
         * deal with set[ug]id.
         */
        error = exec_handle_sugid(imgp);

        KNOTE(&p->p_klist, NOTE_EXEC);

        if (!vfexec && (p->p_flag & P_TRACED))
                psignal(p, SIGTRAP);

        if (error) {
                goto badtoolate;
        }
        vnode_put(imgp->ip_vp);
        imgp->ip_vp = NULL;
        
        if (load_result.unixproc &&
                create_unix_stack(get_task_map(task),
                                  load_result.user_stack, load_result.customstack, p)) {
                error = load_return_to_errno(LOAD_NOSPACE);
                goto badtoolate;
        }

        if (vfexec) {
                uthread->uu_ar0 = (void *)get_user_regs(thread);
                old_map = vm_map_switch(get_task_map(task));
        }

        if (load_result.unixproc) {
                user_addr_t     ap;

                /*
                 * Copy the strings area out into the new process address
                 * space.
                 */
                ap = p->user_stack;
                error = exec_copyout_strings(imgp, &ap);
                if (error) {
                        if (vfexec)
                                vm_map_switch(old_map);
                        goto badtoolate;
                }
                /* Set the stack */
                thread_setuserstack(thread, ap);
        }
        
        if (load_result.dynlinker) {
                uint64_t        ap;

                /* Adjust the stack */
                if (imgp->ip_flags & IMGPF_IS_64BIT) {
                        ap = thread_adjuserstack(thread, -8);
                        (void)copyoutptr(load_result.mach_header, ap, 8);
                } else {
                        ap = thread_adjuserstack(thread, -4);
                        (void)suword(ap, load_result.mach_header);
                }
        }

        if (vfexec) {
                vm_map_switch(old_map);
        }
        /* Set the entry point */
        thread_setentrypoint(thread, load_result.entry_point);

        /* Stop profiling */
        stopprofclock(p);

        /*
         * Reset signal state.
         */
        execsigs(p, thread);

        /*
         * Close file descriptors
         * which specify close-on-exec.
         */
        fdexec(p);

        /*
         * need to cancel async IO requests that can be cancelled and wait for those
         * already active.  MAY BLOCK!
         */
        _aio_exec( p );

        /* FIXME: Till vmspace inherit is fixed: */
        if (!vfexec && p->vm_shm)
                shmexec(p);
        /* Clean up the semaphores */
        semexit(p);

        /*
         * Remember file name for accounting.
         */
        p->p_acflag &= ~AFORK;
        /* If the translated name isn't NULL, then we want to use
         * that translated name as the name we show as the "real" name.
         * Otherwise, use the name passed into exec.
         */
        if (0 != imgp->ip_p_comm[0]) {
                bcopy((caddr_t)imgp->ip_p_comm, (caddr_t)p->p_comm,
                        sizeof(p->p_comm));
        } else {
                if (imgp->ip_ndp->ni_cnd.cn_namelen > MAXCOMLEN)
                        imgp->ip_ndp->ni_cnd.cn_namelen = MAXCOMLEN;
                bcopy((caddr_t)imgp->ip_ndp->ni_cnd.cn_nameptr, (caddr_t)p->p_comm,
                        (unsigned)imgp->ip_ndp->ni_cnd.cn_namelen);
                p->p_comm[imgp->ip_ndp->ni_cnd.cn_namelen] = '\0';
        }

        {
          /* This is for kdebug */
          long dbg_arg1, dbg_arg2, dbg_arg3, dbg_arg4;

          /* Collect the pathname for tracing */
          kdbg_trace_string(p, &dbg_arg1, &dbg_arg2, &dbg_arg3, &dbg_arg4);



          if (vfexec)
          {
                  KERNEL_DEBUG_CONSTANT1((TRACEDBG_CODE(DBG_TRACE_DATA, 2)) | DBG_FUNC_NONE,
                                        p->p_pid ,0,0,0, (unsigned int)thread);
                  KERNEL_DEBUG_CONSTANT1((TRACEDBG_CODE(DBG_TRACE_STRING, 2)) | DBG_FUNC_NONE,
                                        dbg_arg1, dbg_arg2, dbg_arg3, dbg_arg4, (unsigned int)thread);
          }
          else
          {
                  KERNEL_DEBUG_CONSTANT((TRACEDBG_CODE(DBG_TRACE_DATA, 2)) | DBG_FUNC_NONE,
                                        p->p_pid ,0,0,0,0);
                  KERNEL_DEBUG_CONSTANT((TRACEDBG_CODE(DBG_TRACE_STRING, 2)) | DBG_FUNC_NONE,
                                        dbg_arg1, dbg_arg2, dbg_arg3, dbg_arg4, 0);
          }
        }

                p->p_flag &= ~P_CLASSIC;

        /*
         * mark as execed, wakeup the process that vforked (if any) and tell
         * it that it now has it's own resources back
         */
        p->p_flag |= P_EXEC;
        if (p->p_pptr && (p->p_flag & P_PPWAIT)) {
                p->p_flag &= ~P_PPWAIT;
                wakeup((caddr_t)p->p_pptr);
        }

        if (vfexec && (p->p_flag & P_TRACED)) {
                psignal_vfork(p, new_task, thread, SIGTRAP);
        }

badtoolate:
        if (vfexec) {
                task_deallocate(new_task);
                thread_deallocate(thread);
                if (error)
                        error = 0;
        }

bad:
        return(error);
}




/*
 * Our image activator table; this is the table of the image types we are
 * capable of loading.  We list them in order of preference to ensure the
 * fastest image load speed.
 *
 * XXX hardcoded, for now; should use linker sets
 */
struct execsw {
        int (*ex_imgact)(struct image_params *);
        const char *ex_name;
} execsw[] = {
        { exec_mach_imgact,             "Mach-o Binary" },
        { exec_fat_imgact,              "Fat Binary" },
        { exec_shell_imgact,            "Interpreter Script" },
        { NULL, NULL}
};


/*
 * TODO:        Dynamic linker header address on stack is copied via suword()
 */
/* ARGSUSED */
int
execve(struct proc *p, struct execve_args *uap, register_t *retval)
{
        kauth_cred_t cred = p->p_ucred;
        struct image_params image_params, *imgp;
        struct vnode_attr va;
        struct vnode_attr origva;
        struct nameidata nd;
        struct uthread          *uthread;
        int i;
        int resid, error;
        task_t  task;
        int numthreads;
        int vfexec=0;
        int once = 1;   /* save SGUID-ness for interpreted files */
        char alt_p_comm[sizeof(p->p_comm)] = {0};       /* for Classic */
        int is_64 = IS_64BIT_PROCESS(p);
        int seg = (is_64 ? UIO_USERSPACE64 : UIO_USERSPACE32);
        struct vfs_context context;

        context.vc_proc = p;
        context.vc_ucred = p->p_ucred;  /* XXX must NOT be kauth_cred_get() */


        imgp = &image_params;

        /* Initialize the common data in the image_params structure */
        bzero(imgp, sizeof(*imgp));
        imgp->ip_user_fname = uap->fname;
        imgp->ip_user_argv = uap->argp;
        imgp->ip_user_envv = uap->envp;
        imgp->ip_vattr = &va;
        imgp->ip_origvattr = &origva;
        imgp->ip_vfs_context = &context;
        imgp->ip_flags = (is_64 ? IMGPF_WAS_64BIT : IMGPF_NONE);
        imgp->ip_tws_cache_name = NULL;
        imgp->ip_p_comm = alt_p_comm;           /* for Classic */

        /*
         * XXXAUDIT: Currently, we only audit the pathname of the binary.
         * There may also be poor interaction with dyld.
         */

        task = current_task();
        uthread = get_bsdthread_info(current_thread());

        if (uthread->uu_flag & UT_VFORK) {
                        vfexec = 1; /* Mark in exec */
        } else {
                if (task != kernel_task) { 
                        numthreads = get_task_numacts(task);
                        if (numthreads <= 0 )
                                return(EINVAL);
                        if (numthreads > 1) {
                                return(ENOTSUP);
                        }
                }
        }

        error = execargs_alloc(imgp);
        if (error)
                return(error);
        
        /*
         * XXXAUDIT: Note: the double copyin introduces an audit
         * race.  To correct this race, we must use a single
         * copyin(), e.g. by passing a flag to namei to indicate an
         * external path buffer is being used.
         */
        error = exec_save_path(imgp, uap->fname, seg);
        if (error) {
                execargs_free(imgp);
                return(error);
        }

        /*
         * No app profiles under chroot
         */
        if((p->p_fd->fd_rdir == NULLVP) && (app_profile != 0)) {

                /* grab the name of the file out of its path */
                /* we will need this for lookup within the   */
                /* name file */
                /* Scan backwards for the first '/' or start of string */
                imgp->ip_tws_cache_name = imgp->ip_strendp;
                while (imgp->ip_tws_cache_name[0] != '/') {
                        if(imgp->ip_tws_cache_name == imgp->ip_strings) {
                                imgp->ip_tws_cache_name--;
                                break;
                        }
                        imgp->ip_tws_cache_name--;
                }
                imgp->ip_tws_cache_name++;
        }
        NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | AUDITVNPATH1,
                seg, uap->fname, imgp->ip_vfs_context);

again:
        error = namei(&nd);
        if (error)
                goto bad;
        imgp->ip_ndp = &nd;     /* successful namei(); call nameidone() later */
        imgp->ip_vp = nd.ni_vp; /* if set, need to vnode_put() at some point */

        error = exec_check_permissions(imgp);
        if (error)
                goto bad;

        /* Copy; avoid invocation of an interpreter overwriting the original */
        if (once) {
                once = 0;
                origva = va;
        }

        error = vn_rdwr(UIO_READ, imgp->ip_vp, imgp->ip_vdata, PAGE_SIZE, 0,
                        UIO_SYSSPACE32, IO_NODELOCKED, cred, &resid, p);
        if (error)
                goto bad;
                
encapsulated_binary:
        error = -1;
        for(i = 0; error == -1 && execsw[i].ex_imgact != NULL; i++) {

                error = (*execsw[i].ex_imgact)(imgp);

                switch (error) {
                /* case -1: not claimed: continue */
                case -2:                /* Encapsulated binary */
                        goto encapsulated_binary;

                case -3:                /* Interpreter */
                        vnode_put(imgp->ip_vp);
                        imgp->ip_vp = NULL;     /* already put */
                        nd.ni_cnd.cn_nameiop = LOOKUP;
                        nd.ni_cnd.cn_flags = (nd.ni_cnd.cn_flags & HASBUF) |
                                                (FOLLOW | LOCKLEAF);


                        nd.ni_segflg = UIO_SYSSPACE32;
                        nd.ni_dirp = CAST_USER_ADDR_T(imgp->ip_interp_name);
                        goto again;

                default:
                        break;
                }
        }
        
        /* call out to allow 3rd party notification of exec. 
         * Ignore result of kauth_authorize_fileop call.
         */
        if (error == 0 && kauth_authorize_fileop_has_listeners()) {
                kauth_authorize_fileop(vfs_context_ucred(&context), KAUTH_FILEOP_EXEC, 
                                                           (uintptr_t)nd.ni_vp, 0);
        }
        
        /* Image not claimed by any activator? */
        if (error == -1)
                error = ENOEXEC;

bad:
        if (imgp->ip_ndp)
                nameidone(imgp->ip_ndp);
        if (imgp->ip_vp)
                vnode_put(imgp->ip_vp);
        if (imgp->ip_strings)
                execargs_free(imgp);
        if (!error && vfexec) {
                        vfork_return(current_thread(), p->p_pptr, p, retval);
                        (void)thread_resume(imgp->ip_vfork_thread);
                        return(0);
        }
        return(error);
}


static int
copyinptr(user_addr_t froma, user_addr_t *toptr, int ptr_size)
{
        int error;

        if (ptr_size == 4) {
                /* 64 bit value containing 32 bit address */
                unsigned int i;

                error = copyin(froma, &i, 4);
                *toptr = CAST_USER_ADDR_T(i);   /* SAFE */
        } else {
                error = copyin(froma, toptr, 8);
        }
        return (error);
}


static int
copyoutptr(user_addr_t ua, user_addr_t ptr, int ptr_size)
{
        int error;

        if (ptr_size == 4) {
                /* 64 bit value containing 32 bit address */
                unsigned int i = CAST_DOWN(unsigned int,ua);    /* SAFE */

                error = copyout(&i, ptr, 4);
        } else {
                error = copyout(&ua, ptr, 8);
        }
        return (error);
}


/*
 * exec_copyout_strings
 *
 * Copy out the strings segment to user space.  The strings segment is put
 * on a preinitialized stack frame.
 *
 * Parameters:  struct image_params *   the image parameter block
 *              int *                   a pointer to the stack offset variable
 *
 * Returns:     0                       Success
 *              !0                      Faiure: errno
 *
 * Implicit returns:
 *              (*stackp)               The stack offset, modified
 *
 * Note:        The strings segment layout is backward, from the beginning
 *              of the top of the stack to consume the minimal amount of
 *              space possible; the returned stack pointer points to the
 *              end of the area consumed (stacks grow upward).
 *
 *              argc is an int; arg[i] are pointers; env[i] are pointers;
 *              exec_path is a pointer; the 0's are (void *)NULL's
 *
 * The stack frame layout is:
 *
 *      +-------------+
 * sp-> |     argc    |
 *      +-------------+
 *      |    arg[0]   |
 *      +-------------+
 *             :
 *             :
 *      +-------------+
 *      | arg[argc-1] |
 *      +-------------+
 *      |      0      |
 *      +-------------+
 *      |    env[0]   |
 *      +-------------+
 *             :
 *             :
 *      +-------------+
 *      |    env[n]   |
 *      +-------------+
 *      |      0      |
 *      +-------------+
 *      |  exec_path  | In MacOS X PR2 Beaker2E the path passed to exec() is
 *      +-------------+ passed on the stack just after the trailing 0 of the
 *      |      0      | the envp[] array as a pointer to a string.
 *      +-------------+
 *      |  PATH AREA  |
 *      +-------------+
 *      | STRING AREA |
 *             :
 *             :
 *      |             | <- p->user_stack
 *      +-------------+
 *
 * Although technically a part of the STRING AREA, we treat the PATH AREA as
 * a separate entity.  This allows us to align the beginning of the PATH AREA
 * to a pointer boundary so that the exec_path, env[i], and argv[i] pointers
 * which preceed it on the stack are properly aligned.
 *
 * TODO:        argc copied with suword(), which takes a 64 bit address
 */
static int
exec_copyout_strings(struct image_params *imgp, user_addr_t *stackp)
{
        struct proc *p = vfs_context_proc(imgp->ip_vfs_context);
        int     ptr_size = (imgp->ip_flags & IMGPF_IS_64BIT) ? 8 : 4;
        char    *argv = imgp->ip_argv;  /* modifiable copy of argv */
        user_addr_t     string_area;    /* *argv[], *env[] */
        user_addr_t     path_area;      /* package launch path */
        user_addr_t     ptr_area;       /* argv[], env[], exec_path */
        user_addr_t     stack;
        int     stringc = imgp->ip_argc + imgp->ip_envc;
        int len;
        int error;
        int strspace;

        stack = *stackp;

        /*
         * Set up pointers to the beginning of the string area, the beginning
         * of the path area, and the beginning of the pointer area (actually,
         * the location of argc, an int, which may be smaller than a pointer,
         * but we use ptr_size worth of space for it, for alignment).
         */
        string_area = stack - (((imgp->ip_strendp - imgp->ip_strings) + ptr_size-1) & ~(ptr_size-1)) - ptr_size;
        path_area = string_area - (((imgp->ip_argv - imgp->ip_strings) + ptr_size-1) & ~(ptr_size-1));
        ptr_area = path_area - ((imgp->ip_argc + imgp->ip_envc + 4) * ptr_size) - ptr_size /*argc*/;

        /* Return the initial stack address: the location of argc */
        *stackp = ptr_area;

        /*
         * Record the size of the arguments area so that sysctl_procargs()
         * can return the argument area without having to parse the arguments.
         */
        p->p_argc = imgp->ip_argc;
        p->p_argslen = (int)(stack - path_area);


        /*
         * Support for new app package launching for Mac OS X allocates
         * the "path" at the begining of the imgp->ip_strings buffer.
         * copy it just before the string area.
         */
        len = 0;
        error = copyoutstr(imgp->ip_strings, path_area,
                                (unsigned)(imgp->ip_argv - imgp->ip_strings),
                                (size_t *)&len);
        if (error)
                goto bad;


        /* Save a NULL pointer below it */
        (void)copyoutptr(0LL, path_area - ptr_size, ptr_size);

        /* Save the pointer to "path" just below it */
        (void)copyoutptr(path_area, path_area - 2*ptr_size, ptr_size);

        /*
         * ptr_size for 2 NULL one each ofter arg[argc -1] and env[n]
         * ptr_size for argc
         * skip over saved path, ptr_size for pointer to path,
         * and ptr_size for the NULL after pointer to path.
         */

        /* argc (int32, stored in a ptr_size area) */
        (void)suword(ptr_area, imgp->ip_argc);
        ptr_area += sizeof(int);
        /* pad to ptr_size, if 64 bit image, to ensure user stack alignment */
        if (imgp->ip_flags & IMGPF_IS_64BIT) {
                (void)suword(ptr_area, 0);      /* int, not long: ignored */
                ptr_area += sizeof(int);
        }


        /*
         * We use (string_area - path_area) here rather than the more
         * intuitive (imgp->ip_argv - imgp->ip_strings) because we are
         * interested in the length of the PATH_AREA in user space,
         * rather than the actual length of the execution path, since
         * it includes alignment padding of the PATH_AREA + STRING_AREA
         * to a ptr_size boundary.
         */
        strspace = SIZE_IMG_STRSPACE - (string_area - path_area);
        for (;;) {
                if (stringc == imgp->ip_envc) {
                        /* argv[n] = NULL */
                        (void)copyoutptr(0LL, ptr_area, ptr_size);
                        ptr_area += ptr_size;
                }
                if (--stringc < 0)
                        break;

                /* pointer: argv[n]/env[n] */
                (void)copyoutptr(string_area, ptr_area, ptr_size);

                /* string : argv[n][]/env[n][] */
                do {
                        if (strspace <= 0) {
                                error = E2BIG;
                                break;
                        }
                        error = copyoutstr(argv, string_area,
                                                (unsigned)strspace,
                                                (size_t *)&len);
                        string_area += len;
                        argv += len;
                        strspace -= len;
                } while (error == ENAMETOOLONG);
                if (error == EFAULT || error == E2BIG)
                        break;  /* bad stack - user's problem */
                ptr_area += ptr_size;
        }
        /* env[n] = NULL */
        (void)copyoutptr(0LL, ptr_area, ptr_size);

bad:
        return(error);
}


/*
 * exec_extract_strings
 *
 * Copy arguments and environment from user space into work area; we may
 * have already copied some early arguments into the work area, and if
 * so, any arguments opied in are appended to those already there.
 *
 * Parameters:  struct image_params *   the image parameter block
 *
 * Returns:     0                       Success
 *              !0                      Failure: errno
 *
 * Implicit returns;
 *              (imgp->ip_argc)         Count of arguments, updated
 *              (imgp->ip_envc)         Count of environment strings, updated
 *
 *
 * Notes:       The argument and environment vectors are user space pointers
 *              to arrays of user space pointers.
 */
static int
exec_extract_strings(struct image_params *imgp)
{
        int error = 0;
        struct proc *p = vfs_context_proc(imgp->ip_vfs_context);
        int seg = (IS_64BIT_PROCESS(p) ? UIO_USERSPACE64 : UIO_USERSPACE32);
        int     ptr_size = (imgp->ip_flags & IMGPF_WAS_64BIT) ? 8 : 4;
        user_addr_t     argv = imgp->ip_user_argv;
        user_addr_t     envv = imgp->ip_user_envv;

        /* Now, get rest of arguments */

        /*
         * If we are running an interpreter, replace the av[0] that was
         * passed to execve() with the fully qualified path name that was
         * passed to execve() for interpreters which do not use the PATH
         * to locate their script arguments.
         */
        if((imgp->ip_flags & IMGPF_INTERPRET) != 0 && argv != 0LL) {
                user_addr_t     arg;

                error = copyinptr(argv, &arg, ptr_size);
                if (error)
                        goto bad;
                if (arg != 0LL && arg != (user_addr_t)-1) {
                        argv += ptr_size;
                        error = exec_add_string(imgp, imgp->ip_user_fname, seg);
                        if (error)
                                goto bad;
                        imgp->ip_argc++;
                }
        }

        while (argv != 0LL) {
                user_addr_t     arg;

                error = copyinptr(argv, &arg, ptr_size);
                if (error)
                        goto bad;

                argv += ptr_size;
                if (arg == 0LL) {
                        break;
                } else if (arg == (user_addr_t)-1) {
                        /* Um... why would it be -1? */
                        error = EFAULT;
                        goto bad;
                }
                /*
                * av[n...] = arg[n]
                */
                error = exec_add_string(imgp, arg, seg);
                if (error)
                        goto bad;
                imgp->ip_argc++;
        }        

        /* Now, get the environment */
        while (envv != 0LL) {
                user_addr_t     env;

                error = copyinptr(envv, &env, ptr_size);
                if (error)
                        goto bad;

                envv += ptr_size;
                if (env == 0LL) {
                        break;
                } else if (env == (user_addr_t)-1) {
                        error = EFAULT;
                        goto bad;
                }
                /*
                * av[n...] = env[n]
                */
                error = exec_add_string(imgp, env, seg);
                if (error)
                        goto bad;
                imgp->ip_envc++;
        }
bad:
        return error;
}


#define unix_stack_size(p)      (p->p_rlimit[RLIMIT_STACK].rlim_cur)

static int
exec_check_permissions(struct image_params *imgp)
{
        struct vnode *vp = imgp->ip_vp;
        struct vnode_attr *vap = imgp->ip_vattr;
        struct proc *p = vfs_context_proc(imgp->ip_vfs_context);
        int error;
        kauth_action_t action;

        /* Only allow execution of regular files */
        if (!vnode_isreg(vp))
                return (EACCES);
        
        /* Get the file attributes that we will be using here and elsewhere */
        VATTR_INIT(vap);
        VATTR_WANTED(vap, va_uid);
        VATTR_WANTED(vap, va_gid);
        VATTR_WANTED(vap, va_mode);
        VATTR_WANTED(vap, va_fsid);
        VATTR_WANTED(vap, va_fileid);
        VATTR_WANTED(vap, va_data_size);
        if ((error = vnode_getattr(vp, vap, imgp->ip_vfs_context)) != 0)
                return (error);

        /*
         * Ensure that at least one execute bit is on - otherwise root
         * will always succeed, and we don't want to happen unless the
         * file really is executable.
         */
        if ((vap->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0)
                return (EACCES);

        /* Disallow zero length files */
        if (vap->va_data_size == 0)
                return (ENOEXEC);

        imgp->ip_arch_offset = (user_size_t)0;
        imgp->ip_arch_size = vap->va_data_size;

        /* Disable setuid-ness for traced programs or if MNT_NOSUID */
        if ((vp->v_mount->mnt_flag & MNT_NOSUID) || (p->p_flag & P_TRACED))
                vap->va_mode &= ~(VSUID | VSGID);

        /* Check for execute permission */
        action = KAUTH_VNODE_EXECUTE;
        /* Traced images must also be readable */
        if (p->p_flag & P_TRACED)
                action |= KAUTH_VNODE_READ_DATA;
        if ((error = vnode_authorize(vp, NULL, action, imgp->ip_vfs_context)) != 0)
                return (error);

        /* Don't let it run if anyone had it open for writing */
        if (vp->v_writecount)
                return (ETXTBSY);


        /* XXX May want to indicate to underlying FS that vnode is open */

        return (error);
}

/*
 * exec_handle_sugid
 *
 * Initially clear the P_SUGID in the process flags; if an SUGID process is
 * exec'ing a non-SUGID image, then  this is the point of no return.
 *
 * If the image being activated is SUGI, then replace the credential with a
 * copy, disable tracing (unless the tracing process is root), reset the
 * mach task port to revoke it, set the P_SUGID bit,
 *
 * If the saved user and group ID will be changing, then make sure it happens
 * to a new credential, rather than a shared one.
 *
 * Set the security token (this is probably obsolete, given that the token
 * should not technically be separate from the credential itself).
 *
 * Parameters:  struct image_params *   the image parameter block
 *
 * Returns:     void                    No failure indication
 *
 * Implicit returns:
 *              <process credential>    Potentially modified/replaced
 *              <task port>             Potentially revoked
 *              <process flags>         P_SUGID bit potentially modified
 *              <security token>        Potentially modified
 */
static int
exec_handle_sugid(struct image_params *imgp)
{
        kauth_cred_t            cred = vfs_context_ucred(imgp->ip_vfs_context);
        struct proc             *p = vfs_context_proc(imgp->ip_vfs_context);
        int                     i;
        int                     error = 0;
        static struct vnode     *dev_null = NULLVP;

        p->p_flag &= ~P_SUGID;

        if (((imgp->ip_origvattr->va_mode & VSUID) != 0 &&
             kauth_cred_getuid(cred) != imgp->ip_origvattr->va_uid) ||
            ((imgp->ip_origvattr->va_mode & VSGID) != 0 &&
             cred->cr_gid != imgp->ip_origvattr->va_gid)) {
#if KTRACE
                /*
                 * If process is being ktraced, turn off - unless
                 * root set it.
                 */
                if (p->p_tracep && !(p->p_traceflag & KTRFAC_ROOT)) {
                        struct vnode *tvp = p->p_tracep;
                        p->p_tracep = NULL;
                        p->p_traceflag = 0;
                        vnode_rele(tvp);
                }
#endif
            /*
                 * Replace the credential with a copy of itself if euid or egid change.
                 */
                if (imgp->ip_origvattr->va_mode & VSUID) {
                        p->p_ucred = kauth_cred_seteuid(p->p_ucred, imgp->ip_origvattr->va_uid);
                }
                if (imgp->ip_origvattr->va_mode & VSGID) {
                        p->p_ucred = kauth_cred_setegid(p->p_ucred, imgp->ip_origvattr->va_gid);
                }

                /*
                 * Have mach reset the task port.  We don't want
                 * anyone who had the task port before a setuid
                 * exec to be able to access/control the task
                 * after.
                 */
                if (current_task() == p->task)
                        ipc_task_reset(p->task);

                p->p_flag |= P_SUGID;

                /* Cache the vnode for /dev/null the first time around */
                if (dev_null == NULLVP) {
                        struct nameidata nd1;

                        NDINIT(&nd1, LOOKUP, FOLLOW, UIO_SYSSPACE32,
                            CAST_USER_ADDR_T("/dev/null"),
                            imgp->ip_vfs_context);

                        if ((error = vn_open(&nd1, FREAD, 0)) == 0) {
                                dev_null = nd1.ni_vp;
                                /*
                                 * vn_open returns with both a use_count
                                 * and an io_count on the found vnode
                                 * drop the io_count, but keep the use_count
                                 */
                                vnode_put(nd1.ni_vp);
                        }
                }

                /* Radar 2261856; setuid security hole fix */
                /* Patch from OpenBSD: A. Ramesh */
                /*
                 * XXX For setuid processes, attempt to ensure that
                 * stdin, stdout, and stderr are already allocated.
                 * We do not want userland to accidentally allocate
                 * descriptors in this range which has implied meaning
                 * to libc.
                 */
                if (dev_null != NULLVP) {
                        for (i = 0; i < 3; i++) {
                                struct fileproc *fp;
                                int indx;

                                if (p->p_fd->fd_ofiles[i] != NULL)
                                        continue;

                                if ((error = falloc(p, &fp, &indx)) != 0)
                                        continue;

                                if ((error = vnode_ref_ext(dev_null, FREAD)) != 0) {
                                        fp_free(p, indx, fp);
                                        break;
                                }

                                fp->f_fglob->fg_flag = FREAD;
                                fp->f_fglob->fg_type = DTYPE_VNODE;
                                fp->f_fglob->fg_ops = &vnops;
                                fp->f_fglob->fg_data = (caddr_t)dev_null;
                                
                                proc_fdlock(p);
                                *fdflags(p, indx) &= ~UF_RESERVED;
                                fp_drop(p, indx, fp, 1);
                                proc_fdunlock(p);
                        }
                        /*
                         * for now we need to drop the reference immediately
                         * since we don't have any mechanism in place to
                         * release it before starting to unmount "/dev"
                         * during a reboot/shutdown
                         */
                        vnode_rele(dev_null);
                        dev_null = NULLVP;
                }
        }

        /*
         * Implement the semantic where the effective user and group become
         * the saved user and group in exec'ed programs.
         */
        p->p_ucred = kauth_cred_setsvuidgid(p->p_ucred, kauth_cred_getuid(p->p_ucred),  p->p_ucred->cr_gid);
        
        /* XXX Obsolete; security token should not be separate from cred */
        set_security_token(p);

        return(error);
}

static kern_return_t
create_unix_stack(vm_map_t map, user_addr_t user_stack, int customstack,
                        struct proc *p)
{
        mach_vm_size_t  size;
        mach_vm_offset_t addr;

        p->user_stack = user_stack;
        if (!customstack) {
                size = mach_vm_round_page(unix_stack_size(p));
                addr = mach_vm_trunc_page(user_stack - size);
                return (mach_vm_allocate(map, &addr, size,
                                        VM_MAKE_TAG(VM_MEMORY_STACK) |
                                        VM_FLAGS_FIXED));
        } else
                return(KERN_SUCCESS);
}

#include <sys/reboot.h>

static char             init_program_name[128] = "/sbin/launchd";
static const char *     other_init = "/sbin/mach_init";

char            init_args[128] = "";

struct execve_args      init_exec_args;
int             init_attempts = 0;


void
load_init_program(struct proc *p)
{
        vm_offset_t     init_addr;
        char            *argv[3];
        int                     error;
        register_t      retval[2];

        error = 0;

        /* init_args are copied in string form directly from bootstrap */
        
        do {
                if (boothowto & RB_INITNAME) {
                        printf("init program? ");
#if FIXME  /* [ */
                        gets(init_program_name, init_program_name);
#endif  /* FIXME ] */
                }

                if (error && ((boothowto & RB_INITNAME) == 0) &&
                                        (init_attempts == 1)) {
                        printf("Load of %s, errno %d, trying %s\n",
                                init_program_name, error, other_init);
                        error = 0;
                        bcopy(other_init, init_program_name,
                                                        sizeof(other_init));
                }

                init_attempts++;

                if (error) {
                        printf("Load of %s failed, errno %d\n",
                                        init_program_name, error);
                        error = 0;
                        boothowto |= RB_INITNAME;
                        continue;
                }

                /*
                 *      Copy out program name.
                 */

                init_addr = VM_MIN_ADDRESS;
                (void) vm_allocate(current_map(), &init_addr,
                                   PAGE_SIZE, VM_FLAGS_ANYWHERE);
                if (init_addr == 0)
                        init_addr++;

                (void) copyout((caddr_t) init_program_name,
                                CAST_USER_ADDR_T(init_addr),
                                (unsigned) sizeof(init_program_name)+1);

                argv[0] = (char *) init_addr;
                init_addr += sizeof(init_program_name);
                init_addr = (vm_offset_t)ROUND_PTR(char, init_addr);

                /*
                 *      Put out first (and only) argument, similarly.
                 *      Assumes everything fits in a page as allocated
                 *      above.
                 */

                (void) copyout((caddr_t) init_args,
                                CAST_USER_ADDR_T(init_addr),
                                (unsigned) sizeof(init_args));

                argv[1] = (char *) init_addr;
                init_addr += sizeof(init_args);
                init_addr = (vm_offset_t)ROUND_PTR(char, init_addr);

                /*
                 *      Null-end the argument list
                 */

                argv[2] = (char *) 0;
                
                /*
                 *      Copy out the argument list.
                 */
                
                (void) copyout((caddr_t) argv,
                                CAST_USER_ADDR_T(init_addr),
                                (unsigned) sizeof(argv));

                /*
                 *      Set up argument block for fake call to execve.
                 */

                init_exec_args.fname = CAST_USER_ADDR_T(argv[0]);
                init_exec_args.argp = CAST_USER_ADDR_T((char **)init_addr);
                init_exec_args.envp = CAST_USER_ADDR_T(0);
                
                /* So that mach_init task 
                 * is set with uid,gid 0 token 
                 */
                set_security_token(p);

                error = execve(p,&init_exec_args,retval);
        } while (error);
}

/*
 * Convert a load_return_t to an errno.
 */
static int 
load_return_to_errno(load_return_t lrtn)
{
        switch (lrtn) {
            case LOAD_SUCCESS:
                        return 0;
            case LOAD_BADARCH:
                return EBADARCH;
            case LOAD_BADMACHO:
                return EBADMACHO;
            case LOAD_SHLIB:
                return ESHLIBVERS;
            case LOAD_NOSPACE:
            case LOAD_RESOURCE:
                return ENOMEM;
            case LOAD_PROTECT:
                return EACCES;
                case LOAD_ENOENT:
                        return ENOENT;
                case LOAD_IOERROR:
                        return EIO;
            case LOAD_FAILURE:
            default:
                return EBADEXEC;
        }
}

#include <mach/mach_types.h>
#include <mach/vm_prot.h>
#include <mach/semaphore.h>
#include <mach/sync_policy.h>
#include <kern/clock.h>
#include <mach/kern_return.h>

extern semaphore_t execve_semaphore;

/*
 * The block of memory used by the execve arguments.  At the same time,
 * we allocate a page so that we can read in the first page of the image.
 */
static int
execargs_alloc(struct image_params *imgp)
{
        kern_return_t kret;

        kret = semaphore_wait(execve_semaphore);
        if (kret != KERN_SUCCESS)
                switch (kret) {
                default:
                        return (EINVAL);
                case KERN_INVALID_ADDRESS:
                case KERN_PROTECTION_FAILURE:
                        return (EACCES);
                case KERN_ABORTED:
                case KERN_OPERATION_TIMED_OUT:
                        return (EINTR);
                }

        kret = kmem_alloc_pageable(bsd_pageable_map, (vm_offset_t *)&imgp->ip_strings, NCARGS + PAGE_SIZE);
        imgp->ip_vdata = imgp->ip_strings + NCARGS;
        if (kret != KERN_SUCCESS) {
                semaphore_signal(execve_semaphore);
                return (ENOMEM);
        }
        return (0);
}

static int
execargs_free(struct image_params *imgp)
{
        kern_return_t kret;

        kmem_free(bsd_pageable_map, (vm_offset_t)imgp->ip_strings, NCARGS + PAGE_SIZE);
        imgp->ip_strings = NULL;

        kret = semaphore_signal(execve_semaphore);
        switch (kret) { 
        case KERN_INVALID_ADDRESS:
        case KERN_PROTECTION_FAILURE:
                return (EINVAL);
        case KERN_ABORTED:
        case KERN_OPERATION_TIMED_OUT:
                return (EINTR);
        case KERN_SUCCESS:
                return(0);
        default:
                return (EINVAL);
        }
}