6deee3a45e
the generic kernel. The actual emulator is a separate LKM. (not finished yet, sorry). Submitted by: sos@freebsd.org & sef@kithrup.com
573 lines
14 KiB
C
573 lines
14 KiB
C
/*
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* Copyright (c) 1993, David Greenman
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by David Greenman
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* 4. The name of the developer may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $Id: kern_exec.c,v 1.11 1995/01/09 16:04:49 davidg Exp $
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/signalvar.h>
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#include <sys/resourcevar.h>
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#include <sys/kernel.h>
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#include <sys/mount.h>
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#include <sys/filedesc.h>
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#include <sys/file.h>
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#include <sys/acct.h>
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#include <sys/exec.h>
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#include <sys/imgact.h>
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#include <sys/stat.h>
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#include <sys/wait.h>
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#include <sys/mman.h>
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#include <sys/malloc.h>
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#include <sys/sysent.h>
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#include <sys/syslog.h>
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#include <sys/shm.h>
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#include <vm/vm.h>
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#include <vm/vm_kern.h>
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#include <machine/reg.h>
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int *exec_copyout_strings __P((struct image_params *));
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static int exec_check_permissions(struct image_params *);
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/*
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* execsw_set is constructed for us by the linker. Each of the items
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* is a pointer to a `const struct execsw', hence the double pointer here.
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*/
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extern const struct linker_set execsw_set;
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const struct execsw **execsw = (const struct execsw **)&execsw_set.ls_items[0];
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/*
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* execve() system call.
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*/
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int
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execve(p, uap, retval)
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struct proc *p;
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register struct execve_args *uap;
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int *retval;
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{
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struct nameidata nd, *ndp;
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int *stack_base;
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int error, len, i;
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struct image_params image_params, *iparams;
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struct vnode *vnodep;
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struct vattr attr;
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char *image_header;
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iparams = &image_params;
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bzero((caddr_t)iparams, sizeof(struct image_params));
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image_header = (char *)0;
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/*
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* Initialize a few constants in the common area
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*/
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iparams->proc = p;
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iparams->uap = uap;
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iparams->attr = &attr;
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/*
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* Allocate temporary demand zeroed space for argument and
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* environment strings
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*/
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error = vm_allocate(exec_map, (vm_offset_t *)&iparams->stringbase,
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ARG_MAX, TRUE);
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if (error) {
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log(LOG_WARNING, "execve: failed to allocate string space\n");
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return (error);
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}
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if (!iparams->stringbase) {
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error = ENOMEM;
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goto exec_fail;
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}
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iparams->stringp = iparams->stringbase;
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iparams->stringspace = ARG_MAX;
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/*
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* Translate the file name. namei() returns a vnode pointer
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* in ni_vp amoung other things.
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*/
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ndp = &nd;
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ndp->ni_cnd.cn_nameiop = LOOKUP;
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ndp->ni_cnd.cn_flags = LOCKLEAF | FOLLOW | SAVENAME;
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ndp->ni_cnd.cn_proc = curproc;
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ndp->ni_cnd.cn_cred = curproc->p_cred->pc_ucred;
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ndp->ni_segflg = UIO_USERSPACE;
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ndp->ni_dirp = uap->fname;
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interpret:
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error = namei(ndp);
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if (error) {
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vm_deallocate(exec_map, (vm_offset_t)iparams->stringbase,
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ARG_MAX);
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goto exec_fail;
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}
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iparams->vnodep = vnodep = ndp->ni_vp;
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if (vnodep == NULL) {
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error = ENOEXEC;
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goto exec_fail_dealloc;
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}
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/*
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* Check file permissions (also 'opens' file)
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*/
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error = exec_check_permissions(iparams);
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if (error)
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goto exec_fail_dealloc;
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/*
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* Map the image header (first page) of the file into
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* kernel address space
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*/
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error = vm_mmap(kernel_map, /* map */
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(vm_offset_t *)&image_header, /* address */
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PAGE_SIZE, /* size */
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VM_PROT_READ, /* protection */
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VM_PROT_READ, /* max protection */
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0, /* flags */
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(caddr_t)vnodep, /* vnode */
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0); /* offset */
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if (error) {
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uprintf("mmap failed: %d\n",error);
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goto exec_fail_dealloc;
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}
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iparams->image_header = image_header;
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/*
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* Loop through list of image activators, calling each one.
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* If there is no match, the activator returns -1. If there
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* is a match, but there was an error during the activation,
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* the error is returned. Otherwise 0 means success. If the
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* image is interpreted, loop back up and try activating
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* the interpreter.
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*/
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for (i = 0; execsw[i]; ++i) {
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if (execsw[i]->ex_imgact)
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error = (*execsw[i]->ex_imgact)(iparams);
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else
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continue;
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if (error == -1)
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continue;
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if (error)
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goto exec_fail_dealloc;
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if (iparams->interpreted) {
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/* free old vnode and name buffer */
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vput(ndp->ni_vp);
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FREE(ndp->ni_cnd.cn_pnbuf, M_NAMEI);
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if (vm_deallocate(kernel_map,
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(vm_offset_t)image_header, PAGE_SIZE))
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panic("execve: header dealloc failed (1)");
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/* set new name to that of the interpreter */
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ndp->ni_segflg = UIO_SYSSPACE;
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ndp->ni_dirp = iparams->interpreter_name;
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ndp->ni_cnd.cn_nameiop = LOOKUP;
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ndp->ni_cnd.cn_flags = LOCKLEAF | FOLLOW | SAVENAME;
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ndp->ni_cnd.cn_proc = curproc;
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ndp->ni_cnd.cn_cred = curproc->p_cred->pc_ucred;
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goto interpret;
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}
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break;
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}
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/* If we made it through all the activators and none matched, exit. */
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if (error == -1) {
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error = ENOEXEC;
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goto exec_fail_dealloc;
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}
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/*
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* Copy out strings (args and env) and initialize stack base
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*/
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stack_base = exec_copyout_strings(iparams);
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p->p_vmspace->vm_minsaddr = (char *)stack_base;
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/*
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* If custom stack fixup routine present for this process
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* let it do the stack setup.
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* Else stuff argument count as first item on stack
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*/
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if (p->p_sysent->sv_fixup)
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(*p->p_sysent->sv_fixup)(&stack_base, iparams);
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else
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*(--stack_base) = iparams->argc;
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/* close files on exec */
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fdcloseexec(p);
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/* reset caught signals */
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execsigs(p);
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/* name this process - nameiexec(p, ndp) */
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len = min(ndp->ni_cnd.cn_namelen,MAXCOMLEN);
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bcopy(ndp->ni_cnd.cn_nameptr, p->p_comm, len);
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p->p_comm[len] = 0;
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/*
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* mark as executable, wakeup any process that was vforked and tell
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* it that it now has it's own resources back
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*/
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p->p_flag |= P_EXEC;
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if (p->p_pptr && (p->p_flag & P_PPWAIT)) {
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p->p_flag &= ~P_PPWAIT;
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wakeup((caddr_t)p->p_pptr);
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}
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/* implement set userid/groupid */
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p->p_flag &= ~P_SUGID;
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/*
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* Turn off kernel tracing for set-id programs, except for
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* root.
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*/
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if (p->p_tracep && (attr.va_mode & (VSUID | VSGID)) &&
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suser(p->p_ucred, &p->p_acflag)) {
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p->p_traceflag = 0;
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vrele(p->p_tracep);
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p->p_tracep = 0;
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}
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if ((attr.va_mode & VSUID) && (p->p_flag & P_TRACED) == 0) {
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p->p_ucred = crcopy(p->p_ucred);
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p->p_ucred->cr_uid = attr.va_uid;
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p->p_flag |= P_SUGID;
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}
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if ((attr.va_mode & VSGID) && (p->p_flag & P_TRACED) == 0) {
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p->p_ucred = crcopy(p->p_ucred);
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p->p_ucred->cr_groups[0] = attr.va_gid;
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p->p_flag |= P_SUGID;
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}
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/*
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* Implement correct POSIX saved uid behavior.
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*/
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p->p_cred->p_svuid = p->p_ucred->cr_uid;
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p->p_cred->p_svgid = p->p_ucred->cr_gid;
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/* mark vnode pure text */
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ndp->ni_vp->v_flag |= VTEXT;
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/*
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* Store the vp for use in procfs
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*/
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if (p->p_textvp) /* release old reference */
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vrele(p->p_textvp);
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VREF(ndp->ni_vp);
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p->p_textvp = ndp->ni_vp;
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/*
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* If tracing the process, trap to debugger so breakpoints
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* can be set before the program executes.
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*/
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if (p->p_flag & P_TRACED)
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psignal(p, SIGTRAP);
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/* clear "fork but no exec" flag, as we _are_ execing */
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p->p_acflag &= ~AFORK;
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/* Set entry address */
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setregs(p, iparams->entry_addr, (u_long)stack_base);
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/*
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* free various allocated resources
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*/
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if (vm_deallocate(exec_map, (vm_offset_t)iparams->stringbase, ARG_MAX))
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panic("execve: string buffer dealloc failed (1)");
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if (vm_deallocate(kernel_map, (vm_offset_t)image_header, PAGE_SIZE))
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panic("execve: header dealloc failed (2)");
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vput(ndp->ni_vp);
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FREE(ndp->ni_cnd.cn_pnbuf, M_NAMEI);
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return (0);
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exec_fail_dealloc:
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if (iparams->stringbase && iparams->stringbase != (char *)-1)
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if (vm_deallocate(exec_map, (vm_offset_t)iparams->stringbase,
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ARG_MAX))
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panic("execve: string buffer dealloc failed (2)");
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if (iparams->image_header && iparams->image_header != (char *)-1)
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if (vm_deallocate(kernel_map,
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(vm_offset_t)iparams->image_header, PAGE_SIZE))
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panic("execve: header dealloc failed (3)");
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vput(ndp->ni_vp);
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FREE(ndp->ni_cnd.cn_pnbuf, M_NAMEI);
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exec_fail:
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if (iparams->vmspace_destroyed) {
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/* sorry, no more process anymore. exit gracefully */
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#if 0 /* XXX */
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vm_deallocate(&vs->vm_map, USRSTACK - MAXSSIZ, MAXSSIZ);
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#endif
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exit1(p, W_EXITCODE(0, SIGABRT));
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/* NOT REACHED */
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return(0);
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} else {
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return(error);
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}
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}
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/*
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* Destroy old address space, and allocate a new stack
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* The new stack is only SGROWSIZ large because it is grown
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* automatically in trap.c.
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*/
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int
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exec_new_vmspace(iparams)
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struct image_params *iparams;
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{
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int error;
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struct vmspace *vmspace = iparams->proc->p_vmspace;
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caddr_t stack_addr = (caddr_t) (USRSTACK - SGROWSIZ);
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iparams->vmspace_destroyed = 1;
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/* Blow away entire process VM */
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#ifdef SYSVSHM
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if (vmspace->vm_shm)
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shmexit(iparams->proc);
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#endif
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vm_deallocate(&vmspace->vm_map, 0, USRSTACK);
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/* Allocate a new stack */
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error = vm_allocate(&vmspace->vm_map, (vm_offset_t *)&stack_addr,
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SGROWSIZ, FALSE);
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if (error)
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return(error);
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vmspace->vm_ssize = SGROWSIZ >> PAGE_SHIFT;
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/* Initialize maximum stack address */
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vmspace->vm_maxsaddr = (char *)USRSTACK - MAXSSIZ;
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return(0);
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}
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/*
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* Copy out argument and environment strings from the old process
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* address space into the temporary string buffer.
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*/
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int
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exec_extract_strings(iparams)
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struct image_params *iparams;
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{
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char **argv, **envv;
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char *argp, *envp;
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int error, length;
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/*
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* extract arguments first
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*/
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argv = iparams->uap->argv;
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if (argv) {
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while ((argp = (caddr_t) fuword(argv++))) {
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if (argp == (caddr_t) -1)
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return (EFAULT);
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if ((error = copyinstr(argp, iparams->stringp,
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iparams->stringspace, &length))) {
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if (error == ENAMETOOLONG)
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return(E2BIG);
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return (error);
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}
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iparams->stringspace -= length;
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iparams->stringp += length;
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iparams->argc++;
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}
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}
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/*
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* extract environment strings
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*/
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envv = iparams->uap->envv;
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if (envv) {
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while ((envp = (caddr_t) fuword(envv++))) {
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if (envp == (caddr_t) -1)
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return (EFAULT);
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if ((error = copyinstr(envp, iparams->stringp,
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iparams->stringspace, &length))) {
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if (error == ENAMETOOLONG)
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return(E2BIG);
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return (error);
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}
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iparams->stringspace -= length;
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iparams->stringp += length;
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iparams->envc++;
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}
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}
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return (0);
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}
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/*
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* Copy strings out to the new process address space, constructing
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* new arg and env vector tables. Return a pointer to the base
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* so that it can be used as the initial stack pointer.
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*/
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int *
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exec_copyout_strings(iparams)
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struct image_params *iparams;
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{
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int argc, envc;
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char **vectp;
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char *stringp, *destp;
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int *stack_base;
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struct ps_strings *arginfo;
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/*
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* Calculate string base and vector table pointers.
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*/
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arginfo = PS_STRINGS;
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destp = (caddr_t)arginfo - roundup((ARG_MAX - iparams->stringspace), sizeof(char *));
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/*
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* The '+ 2' is for the null pointers at the end of each of the
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* arg and env vector sets
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*/
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vectp = (char **) (destp -
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(iparams->argc + iparams->envc + 2) * sizeof(char *));
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/*
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* vectp also becomes our initial stack base
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*/
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stack_base = (int *)vectp;
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stringp = iparams->stringbase;
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argc = iparams->argc;
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envc = iparams->envc;
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/*
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* Fill in "ps_strings" struct for ps, w, etc.
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*/
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arginfo->ps_argvstr = destp;
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arginfo->ps_nargvstr = argc;
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/*
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* Copy the arg strings and fill in vector table as we go.
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*/
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for (; argc > 0; --argc) {
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*(vectp++) = destp;
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while ((*destp++ = *stringp++));
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}
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/* a null vector table pointer seperates the argp's from the envp's */
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*(vectp++) = NULL;
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arginfo->ps_envstr = destp;
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arginfo->ps_nenvstr = envc;
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/*
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* Copy the env strings and fill in vector table as we go.
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*/
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for (; envc > 0; --envc) {
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*(vectp++) = destp;
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while ((*destp++ = *stringp++));
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}
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/* end of vector table is a null pointer */
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*vectp = NULL;
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return (stack_base);
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}
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/*
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* Check permissions of file to execute.
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* Return 0 for success or error code on failure.
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*/
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static int
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exec_check_permissions(iparams)
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struct image_params *iparams;
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{
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struct proc *p = iparams->proc;
|
|
struct vnode *vnodep = iparams->vnodep;
|
|
struct vattr *attr = iparams->attr;
|
|
int error;
|
|
|
|
/*
|
|
* Check number of open-for-writes on the file and deny execution
|
|
* if there are any.
|
|
*/
|
|
if (vnodep->v_writecount) {
|
|
return (ETXTBSY);
|
|
}
|
|
|
|
/* Get file attributes */
|
|
error = VOP_GETATTR(vnodep, attr, p->p_ucred, p);
|
|
if (error)
|
|
return (error);
|
|
|
|
/*
|
|
* 1) Check if file execution is disabled for the filesystem that this
|
|
* file resides on.
|
|
* 2) Insure 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.
|
|
* 3) Insure that the file is a regular file.
|
|
*/
|
|
if ((vnodep->v_mount->mnt_flag & MNT_NOEXEC) ||
|
|
((attr->va_mode & 0111) == 0) ||
|
|
(attr->va_type != VREG)) {
|
|
return (EACCES);
|
|
}
|
|
|
|
/*
|
|
* Zero length files can't be exec'd
|
|
*/
|
|
if (attr->va_size == 0)
|
|
return (ENOEXEC);
|
|
|
|
/*
|
|
* Disable setuid/setgid if the filesystem prohibits it or if
|
|
* the process is being traced.
|
|
*/
|
|
if ((vnodep->v_mount->mnt_flag & MNT_NOSUID) || (p->p_flag & P_TRACED))
|
|
attr->va_mode &= ~(VSUID | VSGID);
|
|
|
|
/*
|
|
* Check for execute permission to file based on current credentials.
|
|
* Then call filesystem specific open routine (which does nothing
|
|
* in the general case).
|
|
*/
|
|
error = VOP_ACCESS(vnodep, VEXEC, p->p_ucred, p);
|
|
if (error)
|
|
return (error);
|
|
|
|
error = VOP_OPEN(vnodep, FREAD, p->p_ucred, p);
|
|
if (error)
|
|
return (error);
|
|
|
|
return (0);
|
|
}
|