The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_exec.c

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    1 /*-
    2  * Copyright (c) 1993, David Greenman
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  *
   14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   24  * SUCH DAMAGE.
   25  */
   26 
   27 #include <sys/cdefs.h>
   28 __FBSDID("$FreeBSD: releng/5.4/sys/kern/kern_exec.c 145335 2005-04-20 19:11:07Z cvs2svn $");
   29 
   30 #include "opt_ktrace.h"
   31 #include "opt_mac.h"
   32 
   33 #include <sys/param.h>
   34 #include <sys/systm.h>
   35 #include <sys/eventhandler.h>
   36 #include <sys/lock.h>
   37 #include <sys/mutex.h>
   38 #include <sys/sysproto.h>
   39 #include <sys/signalvar.h>
   40 #include <sys/kernel.h>
   41 #include <sys/mac.h>
   42 #include <sys/mount.h>
   43 #include <sys/filedesc.h>
   44 #include <sys/fcntl.h>
   45 #include <sys/acct.h>
   46 #include <sys/exec.h>
   47 #include <sys/imgact.h>
   48 #include <sys/imgact_elf.h>
   49 #include <sys/wait.h>
   50 #include <sys/malloc.h>
   51 #include <sys/proc.h>
   52 #include <sys/pioctl.h>
   53 #include <sys/namei.h>
   54 #include <sys/resourcevar.h>
   55 #include <sys/sf_buf.h>
   56 #include <sys/sysent.h>
   57 #include <sys/shm.h>
   58 #include <sys/sysctl.h>
   59 #include <sys/vnode.h>
   60 #ifdef KTRACE
   61 #include <sys/ktrace.h>
   62 #endif
   63 
   64 #include <vm/vm.h>
   65 #include <vm/vm_param.h>
   66 #include <vm/pmap.h>
   67 #include <vm/vm_page.h>
   68 #include <vm/vm_map.h>
   69 #include <vm/vm_kern.h>
   70 #include <vm/vm_extern.h>
   71 #include <vm/vm_object.h>
   72 #include <vm/vm_pager.h>
   73 
   74 #include <machine/reg.h>
   75 
   76 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments");
   77 
   78 static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS);
   79 static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS);
   80 static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS);
   81 static int kern_execve(struct thread *td, char *fname, char **argv,
   82         char **envv, struct mac *mac_p);
   83 static int do_execve(struct thread *td, char *fname, char **argv,
   84         char **envv, struct mac *mac_p);
   85 
   86 /* XXX This should be vm_size_t. */
   87 SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD,
   88     NULL, 0, sysctl_kern_ps_strings, "LU", "");
   89 
   90 /* XXX This should be vm_size_t. */
   91 SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD,
   92     NULL, 0, sysctl_kern_usrstack, "LU", "");
   93 
   94 SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD,
   95     NULL, 0, sysctl_kern_stackprot, "I", "");
   96 
   97 u_long ps_arg_cache_limit = PAGE_SIZE / 16;
   98 SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 
   99     &ps_arg_cache_limit, 0, "");
  100 
  101 static int
  102 sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS)
  103 {
  104         struct proc *p;
  105         int error;
  106 
  107         p = curproc;
  108 #if defined(__amd64__) || defined(__ia64__)
  109         if (req->oldlen == sizeof(unsigned int)) {
  110                 unsigned int val;
  111                 val = (unsigned int)p->p_sysent->sv_psstrings;
  112                 error = SYSCTL_OUT(req, &val, sizeof(val));
  113         } else
  114 #endif
  115                 error = SYSCTL_OUT(req, &p->p_sysent->sv_psstrings,
  116                    sizeof(p->p_sysent->sv_psstrings));
  117         return error;
  118 }
  119 
  120 static int
  121 sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS)
  122 {
  123         struct proc *p;
  124         int error;
  125 
  126         p = curproc;
  127 #if defined(__amd64__) || defined(__ia64__)
  128         if (req->oldlen == sizeof(unsigned int)) {
  129                 unsigned int val;
  130                 val = (unsigned int)p->p_sysent->sv_usrstack;
  131                 error = SYSCTL_OUT(req, &val, sizeof(val));
  132         } else
  133 #endif
  134                 error = SYSCTL_OUT(req, &p->p_sysent->sv_usrstack,
  135                     sizeof(p->p_sysent->sv_usrstack));
  136         return error;
  137 }
  138 
  139 static int
  140 sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS)
  141 {
  142         struct proc *p;
  143 
  144         p = curproc;
  145         return (SYSCTL_OUT(req, &p->p_sysent->sv_stackprot,
  146             sizeof(p->p_sysent->sv_stackprot)));
  147 }
  148 
  149 /*
  150  * Each of the items is a pointer to a `const struct execsw', hence the
  151  * double pointer here.
  152  */
  153 static const struct execsw **execsw;
  154 
  155 #ifndef _SYS_SYSPROTO_H_
  156 struct execve_args {
  157         char    *fname; 
  158         char    **argv;
  159         char    **envv; 
  160 };
  161 #endif
  162 
  163 /*
  164  * MPSAFE
  165  */
  166 int
  167 execve(td, uap)
  168         struct thread *td;
  169         struct execve_args /* {
  170                 char *fname;
  171                 char **argv;
  172                 char **envv;
  173         } */ *uap;
  174 {
  175 
  176         return (kern_execve(td, uap->fname, uap->argv, uap->envv, NULL));
  177 }
  178 
  179 #ifndef _SYS_SYSPROTO_H_
  180 struct __mac_execve_args {
  181         char    *fname;
  182         char    **argv;
  183         char    **envv;
  184         struct mac      *mac_p;
  185 };
  186 #endif
  187 
  188 /*
  189  * MPSAFE
  190  */
  191 int
  192 __mac_execve(td, uap)
  193         struct thread *td;
  194         struct __mac_execve_args /* {
  195                 char *fname;
  196                 char **argv;
  197                 char **envv;
  198                 struct mac *mac_p;
  199         } */ *uap;
  200 {
  201 
  202 #ifdef MAC
  203         return (kern_execve(td, uap->fname, uap->argv, uap->envv,
  204             uap->mac_p));
  205 #else
  206         return (ENOSYS);
  207 #endif
  208 }
  209 
  210 static int
  211 kern_execve(td, fname, argv, envv, mac_p)
  212         struct thread *td;
  213         char *fname;
  214         char **argv;
  215         char **envv;
  216         struct mac *mac_p;
  217 {
  218         struct proc *p = td->td_proc;
  219         int error;
  220 
  221         if (p->p_flag & P_HADTHREADS) {
  222                 PROC_LOCK(p);
  223                 if (thread_single(SINGLE_BOUNDARY)) {
  224                         PROC_UNLOCK(p);
  225                         return (ERESTART);      /* Try again later. */
  226                 }
  227                 PROC_UNLOCK(p);
  228         }
  229 
  230         error = do_execve(td, fname, argv, envv, mac_p);
  231 
  232         if (p->p_flag & P_HADTHREADS) {
  233                 PROC_LOCK(p);
  234                 /*
  235                  * If success, we upgrade to SINGLE_EXIT state to
  236                  * force other threads to suicide.
  237                  */
  238                 if (error == 0)
  239                         thread_single(SINGLE_EXIT);             
  240                 else
  241                         thread_single_end();
  242                 PROC_UNLOCK(p);
  243         }
  244 
  245         return (error);
  246 }
  247 
  248 /*
  249  * In-kernel implementation of execve().  All arguments are assumed to be
  250  * userspace pointers from the passed thread.
  251  *
  252  * MPSAFE
  253  */
  254 static int
  255 do_execve(td, fname, argv, envv, mac_p)
  256         struct thread *td;
  257         char *fname;
  258         char **argv;
  259         char **envv;
  260         struct mac *mac_p;
  261 {
  262         struct proc *p = td->td_proc;
  263         struct nameidata nd, *ndp;
  264         struct ucred *newcred = NULL, *oldcred;
  265         struct uidinfo *euip;
  266         register_t *stack_base;
  267         int error, len, i;
  268         struct image_params image_params, *imgp;
  269         struct vattr attr;
  270         int (*img_first)(struct image_params *);
  271         struct pargs *oldargs = NULL, *newargs = NULL;
  272         struct sigacts *oldsigacts, *newsigacts;
  273 #ifdef KTRACE
  274         struct vnode *tracevp = NULL;
  275         struct ucred *tracecred = NULL;
  276 #endif
  277         struct vnode *textvp = NULL;
  278         int credential_changing;
  279         int textset;
  280 #ifdef MAC
  281         struct label *interplabel = NULL;
  282         int will_transition;
  283 #endif
  284 
  285         imgp = &image_params;
  286 
  287         /*
  288          * Lock the process and set the P_INEXEC flag to indicate that
  289          * it should be left alone until we're done here.  This is
  290          * necessary to avoid race conditions - e.g. in ptrace() -
  291          * that might allow a local user to illicitly obtain elevated
  292          * privileges.
  293          */
  294         PROC_LOCK(p);
  295         KASSERT((p->p_flag & P_INEXEC) == 0,
  296             ("%s(): process already has P_INEXEC flag", __func__));
  297         p->p_flag |= P_INEXEC;
  298         PROC_UNLOCK(p);
  299 
  300         /*
  301          * Initialize part of the common data
  302          */
  303         imgp->proc = p;
  304         imgp->userspace_argv = argv;
  305         imgp->userspace_envv = envv;
  306         imgp->execlabel = NULL;
  307         imgp->attr = &attr;
  308         imgp->argc = imgp->envc = 0;
  309         imgp->argv0 = NULL;
  310         imgp->entry_addr = 0;
  311         imgp->vmspace_destroyed = 0;
  312         imgp->interpreted = 0;
  313         imgp->interpreter_name[0] = '\0';
  314         imgp->auxargs = NULL;
  315         imgp->vp = NULL;
  316         imgp->object = NULL;
  317         imgp->firstpage = NULL;
  318         imgp->ps_strings = 0;
  319         imgp->auxarg_size = 0;
  320 
  321 #ifdef MAC
  322         error = mac_execve_enter(imgp, mac_p);
  323         if (error) {
  324                 mtx_lock(&Giant);
  325                 goto exec_fail;
  326         }
  327 #endif
  328 
  329         /*
  330          * Allocate temporary demand zeroed space for argument and
  331          *      environment strings
  332          */
  333         imgp->stringbase = (char *)kmem_alloc_wait(exec_map, ARG_MAX);
  334         if (imgp->stringbase == NULL) {
  335                 error = ENOMEM;
  336                 mtx_lock(&Giant);
  337                 goto exec_fail;
  338         }
  339         imgp->stringp = imgp->stringbase;
  340         imgp->stringspace = ARG_MAX;
  341         imgp->image_header = NULL;
  342 
  343         /*
  344          * Translate the file name. namei() returns a vnode pointer
  345          *      in ni_vp amoung other things.
  346          */
  347         ndp = &nd;
  348         NDINIT(ndp, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME,
  349             UIO_USERSPACE, fname, td);
  350 
  351         mtx_lock(&Giant);
  352 interpret:
  353 
  354         error = namei(ndp);
  355         if (error) {
  356                 kmem_free_wakeup(exec_map, (vm_offset_t)imgp->stringbase,
  357                     ARG_MAX);
  358                 goto exec_fail;
  359         }
  360 
  361         imgp->vp = ndp->ni_vp;
  362         imgp->fname = fname;
  363 
  364         /*
  365          * Check file permissions (also 'opens' file)
  366          */
  367         error = exec_check_permissions(imgp);
  368         if (error)
  369                 goto exec_fail_dealloc;
  370 
  371         if (VOP_GETVOBJECT(imgp->vp, &imgp->object) == 0)
  372                 vm_object_reference(imgp->object);
  373 
  374         /*
  375          * Set VV_TEXT now so no one can write to the executable while we're
  376          * activating it.
  377          *
  378          * Remember if this was set before and unset it in case this is not
  379          * actually an executable image.
  380          */
  381         textset = imgp->vp->v_vflag & VV_TEXT;
  382         imgp->vp->v_vflag |= VV_TEXT;
  383 
  384         error = exec_map_first_page(imgp);
  385         if (error)
  386                 goto exec_fail_dealloc;
  387 
  388         /*
  389          *      If the current process has a special image activator it
  390          *      wants to try first, call it.   For example, emulating shell 
  391          *      scripts differently.
  392          */
  393         error = -1;
  394         if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL)
  395                 error = img_first(imgp);
  396 
  397         /*
  398          *      Loop through the list of image activators, calling each one.
  399          *      An activator returns -1 if there is no match, 0 on success,
  400          *      and an error otherwise.
  401          */
  402         for (i = 0; error == -1 && execsw[i]; ++i) {
  403                 if (execsw[i]->ex_imgact == NULL ||
  404                     execsw[i]->ex_imgact == img_first) {
  405                         continue;
  406                 }
  407                 error = (*execsw[i]->ex_imgact)(imgp);
  408         }
  409 
  410         if (error) {
  411                 if (error == -1) {
  412                         if (textset == 0)
  413                                 imgp->vp->v_vflag &= ~VV_TEXT;
  414                         error = ENOEXEC;
  415                 }
  416                 goto exec_fail_dealloc;
  417         }
  418 
  419         /*
  420          * Special interpreter operation, cleanup and loop up to try to
  421          * activate the interpreter.
  422          */
  423         if (imgp->interpreted) {
  424                 exec_unmap_first_page(imgp);
  425                 /*
  426                  * VV_TEXT needs to be unset for scripts.  There is a short
  427                  * period before we determine that something is a script where
  428                  * VV_TEXT will be set. The vnode lock is held over this
  429                  * entire period so nothing should illegitimately be blocked.
  430                  */
  431                 imgp->vp->v_vflag &= ~VV_TEXT;
  432                 /* free name buffer and old vnode */
  433                 NDFREE(ndp, NDF_ONLY_PNBUF);
  434 #ifdef MAC
  435                 interplabel = mac_vnode_label_alloc();
  436                 mac_copy_vnode_label(ndp->ni_vp->v_label, interplabel);
  437 #endif
  438                 vput(ndp->ni_vp);
  439                 vm_object_deallocate(imgp->object);
  440                 imgp->object = NULL;
  441                 /* set new name to that of the interpreter */
  442                 NDINIT(ndp, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME,
  443                     UIO_SYSSPACE, imgp->interpreter_name, td);
  444                 goto interpret;
  445         }
  446 
  447         /*
  448          * Copy out strings (args and env) and initialize stack base
  449          */
  450         if (p->p_sysent->sv_copyout_strings)
  451                 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp);
  452         else
  453                 stack_base = exec_copyout_strings(imgp);
  454 
  455         /*
  456          * If custom stack fixup routine present for this process
  457          * let it do the stack setup.
  458          * Else stuff argument count as first item on stack
  459          */
  460         if (p->p_sysent->sv_fixup != NULL)
  461                 (*p->p_sysent->sv_fixup)(&stack_base, imgp);
  462         else
  463                 suword(--stack_base, imgp->argc);
  464 
  465         /*
  466          * For security and other reasons, the file descriptor table cannot
  467          * be shared after an exec.
  468          */
  469         fdunshare(p, td);
  470 
  471         /*
  472          * Malloc things before we need locks.
  473          */
  474         newcred = crget();
  475         euip = uifind(attr.va_uid);
  476         i = imgp->endargs - imgp->stringbase;
  477         if (ps_arg_cache_limit >= i + sizeof(struct pargs))
  478                 newargs = pargs_alloc(i);
  479 
  480         /* close files on exec */
  481         fdcloseexec(td);
  482 
  483         /* Get a reference to the vnode prior to locking the proc */
  484         VREF(ndp->ni_vp);
  485 
  486         /*
  487          * For security and other reasons, signal handlers cannot
  488          * be shared after an exec. The new process gets a copy of the old
  489          * handlers. In execsigs(), the new process will have its signals
  490          * reset.
  491          */
  492         PROC_LOCK(p);
  493         if (sigacts_shared(p->p_sigacts)) {
  494                 oldsigacts = p->p_sigacts;
  495                 PROC_UNLOCK(p);
  496                 newsigacts = sigacts_alloc();
  497                 sigacts_copy(newsigacts, oldsigacts);
  498                 PROC_LOCK(p);
  499                 p->p_sigacts = newsigacts;
  500         } else
  501                 oldsigacts = NULL;
  502 
  503         /* Stop profiling */
  504         stopprofclock(p);
  505 
  506         /* reset caught signals */
  507         execsigs(p);
  508 
  509         /* name this process - nameiexec(p, ndp) */
  510         len = min(ndp->ni_cnd.cn_namelen,MAXCOMLEN);
  511         bcopy(ndp->ni_cnd.cn_nameptr, p->p_comm, len);
  512         p->p_comm[len] = 0;
  513 
  514         /*
  515          * mark as execed, wakeup the process that vforked (if any) and tell
  516          * it that it now has its own resources back
  517          */
  518         p->p_flag |= P_EXEC;
  519         if (p->p_pptr && (p->p_flag & P_PPWAIT)) {
  520                 p->p_flag &= ~P_PPWAIT;
  521                 wakeup(p->p_pptr);
  522         }
  523 
  524         /*
  525          * Implement image setuid/setgid.
  526          *
  527          * Don't honor setuid/setgid if the filesystem prohibits it or if
  528          * the process is being traced.
  529          *
  530          * XXXMAC: For the time being, use NOSUID to also prohibit
  531          * transitions on the file system.
  532          */
  533         oldcred = p->p_ucred;
  534         credential_changing = 0;
  535         credential_changing |= (attr.va_mode & VSUID) && oldcred->cr_uid !=
  536             attr.va_uid;
  537         credential_changing |= (attr.va_mode & VSGID) && oldcred->cr_gid !=
  538             attr.va_gid;
  539 #ifdef MAC
  540         will_transition = mac_execve_will_transition(oldcred, imgp->vp,
  541             interplabel, imgp);
  542         credential_changing |= will_transition;
  543 #endif
  544 
  545         if (credential_changing &&
  546             (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 &&
  547             (p->p_flag & P_TRACED) == 0) {
  548                 /*
  549                  * Turn off syscall tracing for set-id programs, except for
  550                  * root.  Record any set-id flags first to make sure that
  551                  * we do not regain any tracing during a possible block.
  552                  */
  553                 setsugid(p);
  554 #ifdef KTRACE
  555                 if (p->p_tracevp != NULL && suser_cred(oldcred, SUSER_ALLOWJAIL)) {
  556                         mtx_lock(&ktrace_mtx);
  557                         p->p_traceflag = 0;
  558                         tracevp = p->p_tracevp;
  559                         p->p_tracevp = NULL;
  560                         tracecred = p->p_tracecred;
  561                         p->p_tracecred = NULL;
  562                         mtx_unlock(&ktrace_mtx);
  563                 }
  564 #endif
  565                 /*
  566                  * Close any file descriptors 0..2 that reference procfs,
  567                  * then make sure file descriptors 0..2 are in use.
  568                  *
  569                  * setugidsafety() may call closef() and then pfind()
  570                  * which may grab the process lock.
  571                  * fdcheckstd() may call falloc() which may block to
  572                  * allocate memory, so temporarily drop the process lock.
  573                  */
  574                 PROC_UNLOCK(p);
  575                 setugidsafety(td);
  576                 error = fdcheckstd(td);
  577                 if (error != 0)
  578                         goto done1;
  579                 PROC_LOCK(p);
  580                 /*
  581                  * Set the new credentials.
  582                  */
  583                 crcopy(newcred, oldcred);
  584                 if (attr.va_mode & VSUID)
  585                         change_euid(newcred, euip);
  586                 if (attr.va_mode & VSGID)
  587                         change_egid(newcred, attr.va_gid);
  588 #ifdef MAC
  589                 if (will_transition) {
  590                         mac_execve_transition(oldcred, newcred, imgp->vp,
  591                             interplabel, imgp);
  592                 }
  593 #endif
  594                 /*
  595                  * Implement correct POSIX saved-id behavior.
  596                  *
  597                  * XXXMAC: Note that the current logic will save the
  598                  * uid and gid if a MAC domain transition occurs, even
  599                  * though maybe it shouldn't.
  600                  */
  601                 change_svuid(newcred, newcred->cr_uid);
  602                 change_svgid(newcred, newcred->cr_gid);
  603                 p->p_ucred = newcred;
  604                 newcred = NULL;
  605         } else {
  606                 if (oldcred->cr_uid == oldcred->cr_ruid &&
  607                     oldcred->cr_gid == oldcred->cr_rgid)
  608                         p->p_flag &= ~P_SUGID;
  609                 /*
  610                  * Implement correct POSIX saved-id behavior.
  611                  *
  612                  * XXX: It's not clear that the existing behavior is
  613                  * POSIX-compliant.  A number of sources indicate that the
  614                  * saved uid/gid should only be updated if the new ruid is
  615                  * not equal to the old ruid, or the new euid is not equal
  616                  * to the old euid and the new euid is not equal to the old
  617                  * ruid.  The FreeBSD code always updates the saved uid/gid.
  618                  * Also, this code uses the new (replaced) euid and egid as
  619                  * the source, which may or may not be the right ones to use.
  620                  */
  621                 if (oldcred->cr_svuid != oldcred->cr_uid ||
  622                     oldcred->cr_svgid != oldcred->cr_gid) {
  623                         crcopy(newcred, oldcred);
  624                         change_svuid(newcred, newcred->cr_uid);
  625                         change_svgid(newcred, newcred->cr_gid);
  626                         p->p_ucred = newcred;
  627                         newcred = NULL;
  628                 }
  629         }
  630 
  631         /*
  632          * Store the vp for use in procfs.  This vnode was referenced prior
  633          * to locking the proc lock.
  634          */
  635         textvp = p->p_textvp;
  636         p->p_textvp = ndp->ni_vp;
  637 
  638         /*
  639          * Notify others that we exec'd, and clear the P_INEXEC flag
  640          * as we're now a bona fide freshly-execed process.
  641          */
  642         KNOTE_LOCKED(&p->p_klist, NOTE_EXEC);
  643         p->p_flag &= ~P_INEXEC;
  644 
  645         /*
  646          * If tracing the process, trap to debugger so breakpoints
  647          * can be set before the program executes.
  648          * Use tdsignal to deliver signal to current thread, use
  649          * psignal may cause the signal to be delivered to wrong thread
  650          * because that thread will exit, remember we are going to enter
  651          * single thread mode.
  652          */
  653         if (p->p_flag & P_TRACED)
  654                 tdsignal(td, SIGTRAP, SIGTARGET_TD);
  655 
  656         /* clear "fork but no exec" flag, as we _are_ execing */
  657         p->p_acflag &= ~AFORK;
  658 
  659         /* Free any previous argument cache */
  660         oldargs = p->p_args;
  661         p->p_args = NULL;
  662 
  663         /* Cache arguments if they fit inside our allowance */
  664         if (ps_arg_cache_limit >= i + sizeof(struct pargs)) {
  665                 bcopy(imgp->stringbase, newargs->ar_args, i);
  666                 p->p_args = newargs;
  667                 newargs = NULL;
  668         }
  669         PROC_UNLOCK(p);
  670 
  671         /* Set values passed into the program in registers. */
  672         if (p->p_sysent->sv_setregs)
  673                 (*p->p_sysent->sv_setregs)(td, imgp->entry_addr,
  674                     (u_long)(uintptr_t)stack_base, imgp->ps_strings);
  675         else
  676                 exec_setregs(td, imgp->entry_addr,
  677                     (u_long)(uintptr_t)stack_base, imgp->ps_strings);
  678 
  679 done1:
  680         /*
  681          * Free any resources malloc'd earlier that we didn't use.
  682          */
  683         uifree(euip);
  684         if (newcred == NULL)
  685                 crfree(oldcred);
  686         else
  687                 crfree(newcred);
  688         /*
  689          * Handle deferred decrement of ref counts.
  690          */
  691         if (textvp != NULL)
  692                 vrele(textvp);
  693         if (ndp->ni_vp && error != 0)
  694                 vrele(ndp->ni_vp);
  695 #ifdef KTRACE
  696         if (tracevp != NULL)
  697                 vrele(tracevp);
  698         if (tracecred != NULL)
  699                 crfree(tracecred);
  700 #endif
  701         if (oldargs != NULL)
  702                 pargs_drop(oldargs);
  703         if (newargs != NULL)
  704                 pargs_drop(newargs);
  705         if (oldsigacts != NULL)
  706                 sigacts_free(oldsigacts);
  707 
  708 exec_fail_dealloc:
  709 
  710         /*
  711          * free various allocated resources
  712          */
  713         if (imgp->firstpage != NULL)
  714                 exec_unmap_first_page(imgp);
  715 
  716         if (imgp->vp != NULL) {
  717                 NDFREE(ndp, NDF_ONLY_PNBUF);
  718                 vput(imgp->vp);
  719         }
  720 
  721         if (imgp->stringbase != NULL)
  722                 kmem_free_wakeup(exec_map, (vm_offset_t)imgp->stringbase,
  723                     ARG_MAX);
  724 
  725         if (imgp->object != NULL)
  726                 vm_object_deallocate(imgp->object);
  727 
  728         if (error == 0) {
  729                 /*
  730                  * Stop the process here if its stop event mask has
  731                  * the S_EXEC bit set.
  732                  */
  733                 STOPEVENT(p, S_EXEC, 0);
  734                 goto done2;
  735         }
  736 
  737 exec_fail:
  738         /* we're done here, clear P_INEXEC */
  739         PROC_LOCK(p);
  740         p->p_flag &= ~P_INEXEC;
  741         PROC_UNLOCK(p);
  742         
  743         if (imgp->vmspace_destroyed) {
  744                 /* sorry, no more process anymore. exit gracefully */
  745 #ifdef MAC
  746                 mac_execve_exit(imgp);
  747                 if (interplabel != NULL)
  748                         mac_vnode_label_free(interplabel);
  749 #endif
  750                 exit1(td, W_EXITCODE(0, SIGABRT));
  751                 /* NOT REACHED */
  752                 error = 0;
  753         }
  754 done2:
  755 #ifdef MAC
  756         mac_execve_exit(imgp);
  757         if (interplabel != NULL)
  758                 mac_vnode_label_free(interplabel);
  759 #endif
  760         mtx_unlock(&Giant);
  761         return (error);
  762 }
  763 
  764 int
  765 exec_map_first_page(imgp)
  766         struct image_params *imgp;
  767 {
  768         int rv, i;
  769         int initial_pagein;
  770         vm_page_t ma[VM_INITIAL_PAGEIN];
  771         vm_object_t object;
  772 
  773         GIANT_REQUIRED;
  774 
  775         if (imgp->firstpage != NULL)
  776                 exec_unmap_first_page(imgp);
  777 
  778         VOP_GETVOBJECT(imgp->vp, &object);
  779         VM_OBJECT_LOCK(object);
  780         ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY);
  781         if ((ma[0]->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) {
  782                 initial_pagein = VM_INITIAL_PAGEIN;
  783                 if (initial_pagein > object->size)
  784                         initial_pagein = object->size;
  785                 for (i = 1; i < initial_pagein; i++) {
  786                         if ((ma[i] = vm_page_lookup(object, i)) != NULL) {
  787                                 if (ma[i]->valid)
  788                                         break;
  789                                 vm_page_lock_queues();
  790                                 if ((ma[i]->flags & PG_BUSY) || ma[i]->busy) {
  791                                         vm_page_unlock_queues();
  792                                         break;
  793                                 }
  794                                 vm_page_busy(ma[i]);
  795                                 vm_page_unlock_queues();
  796                         } else {
  797                                 ma[i] = vm_page_alloc(object, i,
  798                                     VM_ALLOC_NORMAL);
  799                                 if (ma[i] == NULL)
  800                                         break;
  801                         }
  802                 }
  803                 initial_pagein = i;
  804                 rv = vm_pager_get_pages(object, ma, initial_pagein, 0);
  805                 ma[0] = vm_page_lookup(object, 0);
  806                 if ((rv != VM_PAGER_OK) || (ma[0] == NULL) ||
  807                     (ma[0]->valid == 0)) {
  808                         if (ma[0]) {
  809                                 vm_page_lock_queues();
  810                                 pmap_remove_all(ma[0]);
  811                                 vm_page_free(ma[0]);
  812                                 vm_page_unlock_queues();
  813                         }
  814                         VM_OBJECT_UNLOCK(object);
  815                         return (EIO);
  816                 }
  817         }
  818         vm_page_lock_queues();
  819         vm_page_hold(ma[0]);
  820         vm_page_wakeup(ma[0]);
  821         vm_page_unlock_queues();
  822         VM_OBJECT_UNLOCK(object);
  823 
  824         imgp->firstpage = sf_buf_alloc(ma[0], 0);
  825         imgp->image_header = (char *)sf_buf_kva(imgp->firstpage);
  826 
  827         return (0);
  828 }
  829 
  830 void
  831 exec_unmap_first_page(imgp)
  832         struct image_params *imgp;
  833 {
  834         vm_page_t m;
  835 
  836         if (imgp->firstpage != NULL) {
  837                 m = sf_buf_page(imgp->firstpage);
  838                 sf_buf_free(imgp->firstpage);
  839                 imgp->firstpage = NULL;
  840                 vm_page_lock_queues();
  841                 vm_page_unhold(m);
  842                 vm_page_unlock_queues();
  843         }
  844 }
  845 
  846 /*
  847  * Destroy old address space, and allocate a new stack
  848  *      The new stack is only SGROWSIZ large because it is grown
  849  *      automatically in trap.c.
  850  */
  851 int
  852 exec_new_vmspace(imgp, sv)
  853         struct image_params *imgp;
  854         struct sysentvec *sv;
  855 {
  856         int error;
  857         struct proc *p = imgp->proc;
  858         struct vmspace *vmspace = p->p_vmspace;
  859         vm_offset_t stack_addr;
  860         vm_map_t map;
  861 
  862         GIANT_REQUIRED;
  863 
  864         imgp->vmspace_destroyed = 1;
  865 
  866         /* Called with Giant held, do not depend on it! */
  867         EVENTHANDLER_INVOKE(process_exec, p);
  868 
  869         /*
  870          * Here is as good a place as any to do any resource limit cleanups.
  871          * This is needed if a 64 bit binary exec's a 32 bit binary - the
  872          * data size limit may need to be changed to a value that makes
  873          * sense for the 32 bit binary.
  874          */
  875         if (sv->sv_fixlimits != NULL)
  876                 sv->sv_fixlimits(imgp);
  877 
  878         /*
  879          * Blow away entire process VM, if address space not shared,
  880          * otherwise, create a new VM space so that other threads are
  881          * not disrupted
  882          */
  883         map = &vmspace->vm_map;
  884         if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv->sv_minuser &&
  885             vm_map_max(map) == sv->sv_maxuser) {
  886                 shmexit(vmspace);
  887                 pmap_remove_pages(vmspace_pmap(vmspace), vm_map_min(map),
  888                     vm_map_max(map));
  889                 vm_map_remove(map, vm_map_min(map), vm_map_max(map));
  890         } else {
  891                 vmspace_exec(p, sv->sv_minuser, sv->sv_maxuser);
  892                 vmspace = p->p_vmspace;
  893                 map = &vmspace->vm_map;
  894         }
  895 
  896         /* Allocate a new stack */
  897         stack_addr = sv->sv_usrstack - maxssiz;
  898         error = vm_map_stack(map, stack_addr, (vm_size_t)maxssiz,
  899             sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_DOWN);
  900         if (error)
  901                 return (error);
  902 
  903 #ifdef __ia64__
  904         /* Allocate a new register stack */
  905         stack_addr = IA64_BACKINGSTORE;
  906         error = vm_map_stack(map, stack_addr, (vm_size_t)maxssiz,
  907             sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_UP);
  908         if (error)
  909                 return (error);
  910 #endif
  911 
  912         /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the
  913          * VM_STACK case, but they are still used to monitor the size of the
  914          * process stack so we can check the stack rlimit.
  915          */
  916         vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT;
  917         vmspace->vm_maxsaddr = (char *)sv->sv_usrstack - maxssiz;
  918 
  919         return (0);
  920 }
  921 
  922 /*
  923  * Copy out argument and environment strings from the old process
  924  *      address space into the temporary string buffer.
  925  */
  926 int
  927 exec_extract_strings(imgp)
  928         struct image_params *imgp;
  929 {
  930         char    **argv, **envv;
  931         char    *argp, *envp;
  932         int     error;
  933         size_t  length;
  934 
  935         /*
  936          * extract arguments first
  937          */
  938 
  939         argv = imgp->userspace_argv;
  940 
  941         if (argv) {
  942                 argp = (caddr_t)(intptr_t)fuword(argv);
  943                 if (argp == (caddr_t)-1)
  944                         return (EFAULT);
  945                 if (argp)
  946                         argv++;
  947                 if (imgp->argv0)
  948                         argp = imgp->argv0;
  949                 if (argp) {
  950                         do {
  951                                 if (argp == (caddr_t)-1)
  952                                         return (EFAULT);
  953                                 if ((error = copyinstr(argp, imgp->stringp,
  954                                     imgp->stringspace, &length))) {
  955                                         if (error == ENAMETOOLONG)
  956                                                 return (E2BIG);
  957                                         return (error);
  958                                 }
  959                                 imgp->stringspace -= length;
  960                                 imgp->stringp += length;
  961                                 imgp->argc++;
  962                         } while ((argp = (caddr_t)(intptr_t)fuword(argv++)));
  963                 }
  964         } else
  965                 return (EFAULT);
  966 
  967         imgp->endargs = imgp->stringp;
  968 
  969         /*
  970          * extract environment strings
  971          */
  972 
  973         envv = imgp->userspace_envv;
  974 
  975         if (envv) {
  976                 while ((envp = (caddr_t)(intptr_t)fuword(envv++))) {
  977                         if (envp == (caddr_t)-1)
  978                                 return (EFAULT);
  979                         if ((error = copyinstr(envp, imgp->stringp,
  980                             imgp->stringspace, &length))) {
  981                                 if (error == ENAMETOOLONG)
  982                                         return (E2BIG);
  983                                 return (error);
  984                         }
  985                         imgp->stringspace -= length;
  986                         imgp->stringp += length;
  987                         imgp->envc++;
  988                 }
  989         }
  990 
  991         return (0);
  992 }
  993 
  994 /*
  995  * Copy strings out to the new process address space, constructing
  996  *      new arg and env vector tables. Return a pointer to the base
  997  *      so that it can be used as the initial stack pointer.
  998  */
  999 register_t *
 1000 exec_copyout_strings(imgp)
 1001         struct image_params *imgp;
 1002 {
 1003         int argc, envc;
 1004         char **vectp;
 1005         char *stringp, *destp;
 1006         register_t *stack_base;
 1007         struct ps_strings *arginfo;
 1008         struct proc *p;
 1009         int szsigcode;
 1010 
 1011         /*
 1012          * Calculate string base and vector table pointers.
 1013          * Also deal with signal trampoline code for this exec type.
 1014          */
 1015         p = imgp->proc;
 1016         szsigcode = 0;
 1017         arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings;
 1018         if (p->p_sysent->sv_szsigcode != NULL)
 1019                 szsigcode = *(p->p_sysent->sv_szsigcode);
 1020         destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE -
 1021             roundup((ARG_MAX - imgp->stringspace), sizeof(char *));
 1022 
 1023         /*
 1024          * install sigcode
 1025          */
 1026         if (szsigcode)
 1027                 copyout(p->p_sysent->sv_sigcode, ((caddr_t)arginfo -
 1028                     szsigcode), szsigcode);
 1029 
 1030         /*
 1031          * If we have a valid auxargs ptr, prepare some room
 1032          * on the stack.
 1033          */
 1034         if (imgp->auxargs) {
 1035                 /*
 1036                  * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for
 1037                  * lower compatibility.
 1038                  */
 1039                 imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size :
 1040                     (AT_COUNT * 2);
 1041                 /*
 1042                  * The '+ 2' is for the null pointers at the end of each of
 1043                  * the arg and env vector sets,and imgp->auxarg_size is room
 1044                  * for argument of Runtime loader.
 1045                  */
 1046                 vectp = (char **)(destp - (imgp->argc + imgp->envc + 2 +
 1047                     imgp->auxarg_size) * sizeof(char *));
 1048 
 1049         } else 
 1050                 /*
 1051                  * The '+ 2' is for the null pointers at the end of each of
 1052                  * the arg and env vector sets
 1053                  */
 1054                 vectp = (char **)(destp - (imgp->argc + imgp->envc + 2) *
 1055                     sizeof(char *));
 1056 
 1057         /*
 1058          * vectp also becomes our initial stack base
 1059          */
 1060         stack_base = (register_t *)vectp;
 1061 
 1062         stringp = imgp->stringbase;
 1063         argc = imgp->argc;
 1064         envc = imgp->envc;
 1065 
 1066         /*
 1067          * Copy out strings - arguments and environment.
 1068          */
 1069         copyout(stringp, destp, ARG_MAX - imgp->stringspace);
 1070 
 1071         /*
 1072          * Fill in "ps_strings" struct for ps, w, etc.
 1073          */
 1074         suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp);
 1075         suword(&arginfo->ps_nargvstr, argc);
 1076 
 1077         /*
 1078          * Fill in argument portion of vector table.
 1079          */
 1080         for (; argc > 0; --argc) {
 1081                 suword(vectp++, (long)(intptr_t)destp);
 1082                 while (*stringp++ != 0)
 1083                         destp++;
 1084                 destp++;
 1085         }
 1086 
 1087         /* a null vector table pointer separates the argp's from the envp's */
 1088         suword(vectp++, 0);
 1089 
 1090         suword(&arginfo->ps_envstr, (long)(intptr_t)vectp);
 1091         suword(&arginfo->ps_nenvstr, envc);
 1092 
 1093         /*
 1094          * Fill in environment portion of vector table.
 1095          */
 1096         for (; envc > 0; --envc) {
 1097                 suword(vectp++, (long)(intptr_t)destp);
 1098                 while (*stringp++ != 0)
 1099                         destp++;
 1100                 destp++;
 1101         }
 1102 
 1103         /* end of vector table is a null pointer */
 1104         suword(vectp, 0);
 1105 
 1106         return (stack_base);
 1107 }
 1108 
 1109 /*
 1110  * Check permissions of file to execute.
 1111  *      Called with imgp->vp locked.
 1112  *      Return 0 for success or error code on failure.
 1113  */
 1114 int
 1115 exec_check_permissions(imgp)
 1116         struct image_params *imgp;
 1117 {
 1118         struct vnode *vp = imgp->vp;
 1119         struct vattr *attr = imgp->attr;
 1120         struct thread *td;
 1121         int error;
 1122 
 1123         td = curthread;                 /* XXXKSE */
 1124 
 1125         /* Get file attributes */
 1126         error = VOP_GETATTR(vp, attr, td->td_ucred, td);
 1127         if (error)
 1128                 return (error);
 1129 
 1130 #ifdef MAC
 1131         error = mac_check_vnode_exec(td->td_ucred, imgp->vp, imgp);
 1132         if (error)
 1133                 return (error);
 1134 #endif
 1135         
 1136         /*
 1137          * 1) Check if file execution is disabled for the filesystem that this
 1138          *      file resides on.
 1139          * 2) Insure that at least one execute bit is on - otherwise root
 1140          *      will always succeed, and we don't want to happen unless the
 1141          *      file really is executable.
 1142          * 3) Insure that the file is a regular file.
 1143          */
 1144         if ((vp->v_mount->mnt_flag & MNT_NOEXEC) ||
 1145             ((attr->va_mode & 0111) == 0) ||
 1146             (attr->va_type != VREG))
 1147                 return (EACCES);
 1148 
 1149         /*
 1150          * Zero length files can't be exec'd
 1151          */
 1152         if (attr->va_size == 0)
 1153                 return (ENOEXEC);
 1154 
 1155         /*
 1156          *  Check for execute permission to file based on current credentials.
 1157          */
 1158         error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td);
 1159         if (error)
 1160                 return (error);
 1161 
 1162         /*
 1163          * Check number of open-for-writes on the file and deny execution
 1164          * if there are any.
 1165          */
 1166         if (vp->v_writecount)
 1167                 return (ETXTBSY);
 1168 
 1169         /*
 1170          * Call filesystem specific open routine (which does nothing in the
 1171          * general case).
 1172          */
 1173         error = VOP_OPEN(vp, FREAD, td->td_ucred, td, -1);
 1174         return (error);
 1175 }
 1176 
 1177 /*
 1178  * Exec handler registration
 1179  */
 1180 int
 1181 exec_register(execsw_arg)
 1182         const struct execsw *execsw_arg;
 1183 {
 1184         const struct execsw **es, **xs, **newexecsw;
 1185         int count = 2;  /* New slot and trailing NULL */
 1186 
 1187         if (execsw)
 1188                 for (es = execsw; *es; es++)
 1189                         count++;
 1190         newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK);
 1191         if (newexecsw == NULL)
 1192                 return (ENOMEM);
 1193         xs = newexecsw;
 1194         if (execsw)
 1195                 for (es = execsw; *es; es++)
 1196                         *xs++ = *es;
 1197         *xs++ = execsw_arg;
 1198         *xs = NULL;
 1199         if (execsw)
 1200                 free(execsw, M_TEMP);
 1201         execsw = newexecsw;
 1202         return (0);
 1203 }
 1204 
 1205 int
 1206 exec_unregister(execsw_arg)
 1207         const struct execsw *execsw_arg;
 1208 {
 1209         const struct execsw **es, **xs, **newexecsw;
 1210         int count = 1;
 1211 
 1212         if (execsw == NULL)
 1213                 panic("unregister with no handlers left?\n");
 1214 
 1215         for (es = execsw; *es; es++) {
 1216                 if (*es == execsw_arg)
 1217                         break;
 1218         }
 1219         if (*es == NULL)
 1220                 return (ENOENT);
 1221         for (es = execsw; *es; es++)
 1222                 if (*es != execsw_arg)
 1223                         count++;
 1224         newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK);
 1225         if (newexecsw == NULL)
 1226                 return (ENOMEM);
 1227         xs = newexecsw;
 1228         for (es = execsw; *es; es++)
 1229                 if (*es != execsw_arg)
 1230                         *xs++ = *es;
 1231         *xs = NULL;
 1232         if (execsw)
 1233                 free(execsw, M_TEMP);
 1234         execsw = newexecsw;
 1235         return (0);
 1236 }

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