The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]

FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_exec.c

Version: -  FREEBSD  -  FREEBSD-13-STABLE  -  FREEBSD-13-0  -  FREEBSD-12-STABLE  -  FREEBSD-12-0  -  FREEBSD-11-STABLE  -  FREEBSD-11-0  -  FREEBSD-10-STABLE  -  FREEBSD-10-0  -  FREEBSD-9-STABLE  -  FREEBSD-9-0  -  FREEBSD-8-STABLE  -  FREEBSD-8-0  -  FREEBSD-7-STABLE  -  FREEBSD-7-0  -  FREEBSD-6-STABLE  -  FREEBSD-6-0  -  FREEBSD-5-STABLE  -  FREEBSD-5-0  -  FREEBSD-4-STABLE  -  FREEBSD-3-STABLE  -  FREEBSD22  -  l41  -  OPENBSD  -  linux-2.6  -  MK84  -  PLAN9  -  xnu-8792 
SearchContext: -  none  -  3  -  10 

    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  * $FreeBSD: releng/5.0/sys/kern/kern_exec.c 108086 2002-12-19 09:40:13Z alfred $
   27  */
   28 
   29 #include "opt_ktrace.h"
   30 #include "opt_mac.h"
   31 
   32 #include <sys/param.h>
   33 #include <sys/systm.h>
   34 #include <sys/lock.h>
   35 #include <sys/mutex.h>
   36 #include <sys/sysproto.h>
   37 #include <sys/signalvar.h>
   38 #include <sys/kernel.h>
   39 #include <sys/mac.h>
   40 #include <sys/mount.h>
   41 #include <sys/filedesc.h>
   42 #include <sys/fcntl.h>
   43 #include <sys/acct.h>
   44 #include <sys/exec.h>
   45 #include <sys/imgact.h>
   46 #include <sys/imgact_elf.h>
   47 #include <sys/wait.h>
   48 #include <sys/malloc.h>
   49 #include <sys/proc.h>
   50 #include <sys/pioctl.h>
   51 #include <sys/namei.h>
   52 #include <sys/sysent.h>
   53 #include <sys/shm.h>
   54 #include <sys/sysctl.h>
   55 #include <sys/user.h>
   56 #include <sys/vnode.h>
   57 #ifdef KTRACE
   58 #include <sys/ktrace.h>
   59 #endif
   60 
   61 #include <vm/vm.h>
   62 #include <vm/vm_param.h>
   63 #include <vm/pmap.h>
   64 #include <vm/vm_page.h>
   65 #include <vm/vm_map.h>
   66 #include <vm/vm_kern.h>
   67 #include <vm/vm_extern.h>
   68 #include <vm/vm_object.h>
   69 #include <vm/vm_pager.h>
   70 
   71 #include <machine/reg.h>
   72 
   73 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments");
   74 
   75 static MALLOC_DEFINE(M_ATEXEC, "atexec", "atexec callback");
   76 
   77 static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS);
   78 static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS);
   79 static int kern_execve(struct thread *td, char *fname, char **argv,
   80         char **envv, struct mac *mac_p);
   81 
   82 /*
   83  * callout list for things to do at exec time
   84  */
   85 struct execlist {
   86         execlist_fn function;
   87         TAILQ_ENTRY(execlist) next;
   88 };
   89 
   90 TAILQ_HEAD(exec_list_head, execlist);
   91 static struct exec_list_head exec_list = TAILQ_HEAD_INITIALIZER(exec_list);
   92 
   93 /* XXX This should be vm_size_t. */
   94 SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD,
   95     NULL, 0, sysctl_kern_ps_strings, "LU", "");
   96 
   97 /* XXX This should be vm_size_t. */
   98 SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD,
   99     NULL, 0, sysctl_kern_usrstack, "LU", "");
  100 
  101 u_long ps_arg_cache_limit = PAGE_SIZE / 16;
  102 SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 
  103     &ps_arg_cache_limit, 0, "");
  104 
  105 int ps_argsopen = 1;
  106 SYSCTL_INT(_kern, OID_AUTO, ps_argsopen, CTLFLAG_RW, &ps_argsopen, 0, "");
  107 
  108 #ifdef __ia64__
  109 /* XXX HACK */
  110 static int regstkpages = 256;
  111 SYSCTL_INT(_machdep, OID_AUTO, regstkpages, CTLFLAG_RW, &regstkpages, 0, "");
  112 #endif
  113 
  114 static int
  115 sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS)
  116 {
  117         struct proc *p;
  118 
  119         p = curproc;
  120         return (SYSCTL_OUT(req, &p->p_sysent->sv_psstrings,
  121            sizeof(p->p_sysent->sv_psstrings)));
  122 }
  123 
  124 static int
  125 sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS)
  126 {
  127         struct proc *p;
  128 
  129         p = curproc;
  130         return (SYSCTL_OUT(req, &p->p_sysent->sv_usrstack,
  131             sizeof(p->p_sysent->sv_usrstack)));
  132 }
  133 
  134 /*
  135  * Each of the items is a pointer to a `const struct execsw', hence the
  136  * double pointer here.
  137  */
  138 static const struct execsw **execsw;
  139 
  140 /*
  141  * In-kernel implementation of execve().  All arguments are assumed to be
  142  * userspace pointers from the passed thread.
  143  *
  144  * MPSAFE
  145  */
  146 static int
  147 kern_execve(td, fname, argv, envv, mac_p)
  148         struct thread *td;
  149         char *fname;
  150         char **argv;
  151         char **envv;
  152         struct mac *mac_p;
  153 {
  154         struct proc *p = td->td_proc;
  155         struct nameidata nd, *ndp;
  156         struct ucred *newcred = NULL, *oldcred;
  157         struct uidinfo *euip;
  158         register_t *stack_base;
  159         int error, len, i;
  160         struct image_params image_params, *imgp;
  161         struct vattr attr;
  162         int (*img_first)(struct image_params *);
  163         struct pargs *oldargs = NULL, *newargs = NULL;
  164         struct procsig *oldprocsig, *newprocsig;
  165 #ifdef KTRACE
  166         struct vnode *tracevp = NULL;
  167 #endif
  168         struct vnode *textvp = NULL;
  169         int credential_changing;
  170         int textset;
  171 #ifdef MAC
  172         struct label interplabel;       /* label of the interpreted vnode */
  173         struct label execlabel;         /* optional label argument */
  174         int will_transition, interplabelvalid = 0;
  175 #endif
  176 
  177         imgp = &image_params;
  178 
  179         /*
  180          * Lock the process and set the P_INEXEC flag to indicate that
  181          * it should be left alone until we're done here.  This is
  182          * necessary to avoid race conditions - e.g. in ptrace() -
  183          * that might allow a local user to illicitly obtain elevated
  184          * privileges.
  185          */
  186         PROC_LOCK(p);
  187         KASSERT((p->p_flag & P_INEXEC) == 0,
  188             ("%s(): process already has P_INEXEC flag", __func__));
  189         if (p->p_flag & P_KSES) {
  190                 if (thread_single(SINGLE_EXIT)) {
  191                         PROC_UNLOCK(p);
  192                         return (ERESTART);      /* Try again later. */
  193                 }
  194                 /*
  195                  * If we get here all other threads are dead,
  196                  * so unset the associated flags and lose KSE mode.
  197                  */
  198                 p->p_flag &= ~P_KSES;
  199                 td->td_flags &= ~TDF_UNBOUND;
  200                 thread_single_end();
  201         }
  202         p->p_flag |= P_INEXEC;
  203         PROC_UNLOCK(p);
  204 
  205         /*
  206          * Initialize part of the common data
  207          */
  208         imgp->proc = p;
  209         imgp->userspace_argv = argv;
  210         imgp->userspace_envv = envv;
  211         imgp->execlabel = NULL;
  212         imgp->attr = &attr;
  213         imgp->argc = imgp->envc = 0;
  214         imgp->argv0 = NULL;
  215         imgp->entry_addr = 0;
  216         imgp->vmspace_destroyed = 0;
  217         imgp->interpreted = 0;
  218         imgp->interpreter_name[0] = '\0';
  219         imgp->auxargs = NULL;
  220         imgp->vp = NULL;
  221         imgp->object = NULL;
  222         imgp->firstpage = NULL;
  223         imgp->ps_strings = 0;
  224         imgp->auxarg_size = 0;
  225 
  226 #ifdef MAC
  227         error = mac_execve_enter(imgp, mac_p, &execlabel);
  228         if (error) {
  229                 mtx_lock(&Giant);
  230                 goto exec_fail;
  231         }
  232 #endif
  233 
  234         /*
  235          * Allocate temporary demand zeroed space for argument and
  236          *      environment strings
  237          */
  238         imgp->stringbase = (char *)kmem_alloc_wait(exec_map, ARG_MAX +
  239             PAGE_SIZE);
  240         if (imgp->stringbase == NULL) {
  241                 error = ENOMEM;
  242                 mtx_lock(&Giant);
  243                 goto exec_fail;
  244         }
  245         imgp->stringp = imgp->stringbase;
  246         imgp->stringspace = ARG_MAX;
  247         imgp->image_header = imgp->stringbase + ARG_MAX;
  248 
  249         /*
  250          * Translate the file name. namei() returns a vnode pointer
  251          *      in ni_vp amoung other things.
  252          */
  253         ndp = &nd;
  254         NDINIT(ndp, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME,
  255             UIO_USERSPACE, fname, td);
  256 
  257         mtx_lock(&Giant);
  258 interpret:
  259 
  260         error = namei(ndp);
  261         if (error) {
  262                 kmem_free_wakeup(exec_map, (vm_offset_t)imgp->stringbase,
  263                     ARG_MAX + PAGE_SIZE);
  264                 goto exec_fail;
  265         }
  266 
  267         imgp->vp = ndp->ni_vp;
  268         imgp->fname = fname;
  269 
  270         /*
  271          * Check file permissions (also 'opens' file)
  272          */
  273         error = exec_check_permissions(imgp);
  274         if (error)
  275                 goto exec_fail_dealloc;
  276 
  277         if (VOP_GETVOBJECT(imgp->vp, &imgp->object) == 0)
  278                 vm_object_reference(imgp->object);
  279 
  280         /*
  281          * Set VV_TEXT now so no one can write to the executable while we're
  282          * activating it.
  283          *
  284          * Remember if this was set before and unset it in case this is not
  285          * actually an executable image.
  286          */
  287         textset = imgp->vp->v_vflag & VV_TEXT;
  288         imgp->vp->v_vflag |= VV_TEXT;
  289 
  290         error = exec_map_first_page(imgp);
  291         if (error)
  292                 goto exec_fail_dealloc;
  293 
  294         /*
  295          *      If the current process has a special image activator it
  296          *      wants to try first, call it.   For example, emulating shell 
  297          *      scripts differently.
  298          */
  299         error = -1;
  300         if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL)
  301                 error = img_first(imgp);
  302 
  303         /*
  304          *      Loop through the list of image activators, calling each one.
  305          *      An activator returns -1 if there is no match, 0 on success,
  306          *      and an error otherwise.
  307          */
  308         for (i = 0; error == -1 && execsw[i]; ++i) {
  309                 if (execsw[i]->ex_imgact == NULL ||
  310                     execsw[i]->ex_imgact == img_first) {
  311                         continue;
  312                 }
  313                 error = (*execsw[i]->ex_imgact)(imgp);
  314         }
  315 
  316         if (error) {
  317                 if (error == -1) {
  318                         if (textset == 0)
  319                                 imgp->vp->v_vflag &= ~VV_TEXT;
  320                         error = ENOEXEC;
  321                 }
  322                 goto exec_fail_dealloc;
  323         }
  324 
  325         /*
  326          * Special interpreter operation, cleanup and loop up to try to
  327          * activate the interpreter.
  328          */
  329         if (imgp->interpreted) {
  330                 exec_unmap_first_page(imgp);
  331                 /*
  332                  * VV_TEXT needs to be unset for scripts.  There is a short
  333                  * period before we determine that something is a script where
  334                  * VV_TEXT will be set. The vnode lock is held over this
  335                  * entire period so nothing should illegitimately be blocked.
  336                  */
  337                 imgp->vp->v_vflag &= ~VV_TEXT;
  338                 /* free name buffer and old vnode */
  339                 NDFREE(ndp, NDF_ONLY_PNBUF);
  340 #ifdef MAC
  341                 mac_init_vnode_label(&interplabel);
  342                 mac_copy_vnode_label(&ndp->ni_vp->v_label, &interplabel);
  343                 interplabelvalid = 1;
  344 #endif
  345                 vput(ndp->ni_vp);
  346                 vm_object_deallocate(imgp->object);
  347                 imgp->object = NULL;
  348                 /* set new name to that of the interpreter */
  349                 NDINIT(ndp, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME,
  350                     UIO_SYSSPACE, imgp->interpreter_name, td);
  351                 goto interpret;
  352         }
  353 
  354         /*
  355          * Copy out strings (args and env) and initialize stack base
  356          */
  357         if (p->p_sysent->sv_copyout_strings)
  358                 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp);
  359         else
  360                 stack_base = exec_copyout_strings(imgp);
  361 
  362         /*
  363          * If custom stack fixup routine present for this process
  364          * let it do the stack setup.
  365          * Else stuff argument count as first item on stack
  366          */
  367         if (p->p_sysent->sv_fixup)
  368                 (*p->p_sysent->sv_fixup)(&stack_base, imgp);
  369         else
  370                 suword(--stack_base, imgp->argc);
  371 
  372         /*
  373          * For security and other reasons, the file descriptor table cannot
  374          * be shared after an exec.
  375          */
  376         FILEDESC_LOCK(p->p_fd);
  377         if (p->p_fd->fd_refcnt > 1) {
  378                 struct filedesc *tmp;
  379 
  380                 tmp = fdcopy(td);
  381                 FILEDESC_UNLOCK(p->p_fd);
  382                 fdfree(td);
  383                 p->p_fd = tmp;
  384         } else
  385                 FILEDESC_UNLOCK(p->p_fd);
  386 
  387         /*
  388          * Malloc things before we need locks.
  389          */
  390         newcred = crget();
  391         euip = uifind(attr.va_uid);
  392         i = imgp->endargs - imgp->stringbase;
  393         if (ps_arg_cache_limit >= i + sizeof(struct pargs))
  394                 newargs = pargs_alloc(i);
  395 
  396         /* close files on exec */
  397         fdcloseexec(td);
  398 
  399         /* Get a reference to the vnode prior to locking the proc */
  400         VREF(ndp->ni_vp);
  401 
  402         /*
  403          * For security and other reasons, signal handlers cannot
  404          * be shared after an exec. The new process gets a copy of the old
  405          * handlers. In execsigs(), the new process will have its signals
  406          * reset.
  407          */
  408         PROC_LOCK(p);
  409         mp_fixme("procsig needs a lock");
  410         if (p->p_procsig->ps_refcnt > 1) {
  411                 oldprocsig = p->p_procsig;
  412                 PROC_UNLOCK(p);
  413                 MALLOC(newprocsig, struct procsig *, sizeof(struct procsig),
  414                     M_SUBPROC, M_WAITOK);
  415                 bcopy(oldprocsig, newprocsig, sizeof(*newprocsig));
  416                 newprocsig->ps_refcnt = 1;
  417                 oldprocsig->ps_refcnt--;
  418                 PROC_LOCK(p);
  419                 p->p_procsig = newprocsig;
  420                 if (p->p_sigacts == &p->p_uarea->u_sigacts)
  421                         panic("shared procsig but private sigacts?");
  422 
  423                 p->p_uarea->u_sigacts = *p->p_sigacts;
  424                 p->p_sigacts = &p->p_uarea->u_sigacts;
  425         }
  426         /* Stop profiling */
  427         stopprofclock(p);
  428 
  429         /* reset caught signals */
  430         execsigs(p);
  431 
  432         /* name this process - nameiexec(p, ndp) */
  433         len = min(ndp->ni_cnd.cn_namelen,MAXCOMLEN);
  434         bcopy(ndp->ni_cnd.cn_nameptr, p->p_comm, len);
  435         p->p_comm[len] = 0;
  436 
  437         /*
  438          * mark as execed, wakeup the process that vforked (if any) and tell
  439          * it that it now has its own resources back
  440          */
  441         p->p_flag |= P_EXEC;
  442         if (p->p_pptr && (p->p_flag & P_PPWAIT)) {
  443                 p->p_flag &= ~P_PPWAIT;
  444                 wakeup(p->p_pptr);
  445         }
  446 
  447         /*
  448          * Implement image setuid/setgid.
  449          *
  450          * Don't honor setuid/setgid if the filesystem prohibits it or if
  451          * the process is being traced.
  452          *
  453          * XXXMAC: For the time being, use NOSUID to also prohibit
  454          * transitions on the file system.
  455          */
  456         oldcred = p->p_ucred;
  457         credential_changing = 0;
  458         credential_changing |= (attr.va_mode & VSUID) && oldcred->cr_uid !=
  459             attr.va_uid;
  460         credential_changing |= (attr.va_mode & VSGID) && oldcred->cr_gid !=
  461             attr.va_gid;
  462 #ifdef MAC
  463         will_transition = mac_execve_will_transition(oldcred, imgp->vp,
  464             interplabelvalid ? &interplabel : NULL, imgp);
  465         credential_changing |= will_transition;
  466 #endif
  467 
  468         if (credential_changing &&
  469             (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 &&
  470             (p->p_flag & P_TRACED) == 0) {
  471                 /*
  472                  * Turn off syscall tracing for set-id programs, except for
  473                  * root.  Record any set-id flags first to make sure that
  474                  * we do not regain any tracing during a possible block.
  475                  */
  476                 setsugid(p);
  477 #ifdef KTRACE
  478                 if (p->p_tracep && suser_cred(oldcred, PRISON_ROOT)) {
  479                         mtx_lock(&ktrace_mtx);
  480                         p->p_traceflag = 0;
  481                         tracevp = p->p_tracep;
  482                         p->p_tracep = NULL;
  483                         mtx_unlock(&ktrace_mtx);
  484                 }
  485 #endif
  486                 /*
  487                  * Close any file descriptors 0..2 that reference procfs,
  488                  * then make sure file descriptors 0..2 are in use.
  489                  *
  490                  * setugidsafety() may call closef() and then pfind()
  491                  * which may grab the process lock.
  492                  * fdcheckstd() may call falloc() which may block to
  493                  * allocate memory, so temporarily drop the process lock.
  494                  */
  495                 PROC_UNLOCK(p);
  496                 setugidsafety(td);
  497                 error = fdcheckstd(td);
  498                 if (error != 0)
  499                         goto done1;
  500                 PROC_LOCK(p);
  501                 /*
  502                  * Set the new credentials.
  503                  */
  504                 crcopy(newcred, oldcred);
  505                 if (attr.va_mode & VSUID)
  506                         change_euid(newcred, euip);
  507                 if (attr.va_mode & VSGID)
  508                         change_egid(newcred, attr.va_gid);
  509 #ifdef MAC
  510                 if (will_transition) {
  511                         mac_execve_transition(oldcred, newcred, imgp->vp,
  512                             interplabelvalid ? &interplabel : NULL, imgp);
  513                 }
  514 #endif
  515                 /*
  516                  * Implement correct POSIX saved-id behavior.
  517                  *
  518                  * XXXMAC: Note that the current logic will save the
  519                  * uid and gid if a MAC domain transition occurs, even
  520                  * though maybe it shouldn't.
  521                  */
  522                 change_svuid(newcred, newcred->cr_uid);
  523                 change_svgid(newcred, newcred->cr_gid);
  524                 p->p_ucred = newcred;
  525                 newcred = NULL;
  526         } else {
  527                 if (oldcred->cr_uid == oldcred->cr_ruid &&
  528                     oldcred->cr_gid == oldcred->cr_rgid)
  529                         p->p_flag &= ~P_SUGID;
  530                 /*
  531                  * Implement correct POSIX saved-id behavior.
  532                  *
  533                  * XXX: It's not clear that the existing behavior is
  534                  * POSIX-compliant.  A number of sources indicate that the
  535                  * saved uid/gid should only be updated if the new ruid is
  536                  * not equal to the old ruid, or the new euid is not equal
  537                  * to the old euid and the new euid is not equal to the old
  538                  * ruid.  The FreeBSD code always updates the saved uid/gid.
  539                  * Also, this code uses the new (replaced) euid and egid as
  540                  * the source, which may or may not be the right ones to use.
  541                  */
  542                 if (oldcred->cr_svuid != oldcred->cr_uid ||
  543                     oldcred->cr_svgid != oldcred->cr_gid) {
  544                         crcopy(newcred, oldcred);
  545                         change_svuid(newcred, newcred->cr_uid);
  546                         change_svgid(newcred, newcred->cr_gid);
  547                         p->p_ucred = newcred;
  548                         newcred = NULL;
  549                 }
  550         }
  551 
  552         /*
  553          * Store the vp for use in procfs.  This vnode was referenced prior
  554          * to locking the proc lock.
  555          */
  556         textvp = p->p_textvp;
  557         p->p_textvp = ndp->ni_vp;
  558 
  559         /*
  560          * Notify others that we exec'd, and clear the P_INEXEC flag
  561          * as we're now a bona fide freshly-execed process.
  562          */
  563         KNOTE(&p->p_klist, NOTE_EXEC);
  564         p->p_flag &= ~P_INEXEC;
  565 
  566         /*
  567          * If tracing the process, trap to debugger so breakpoints
  568          * can be set before the program executes.
  569          */
  570         if (p->p_flag & P_TRACED)
  571                 psignal(p, SIGTRAP);
  572 
  573         /* clear "fork but no exec" flag, as we _are_ execing */
  574         p->p_acflag &= ~AFORK;
  575 
  576         /* Free any previous argument cache */
  577         oldargs = p->p_args;
  578         p->p_args = NULL;
  579 
  580         /* Cache arguments if they fit inside our allowance */
  581         if (ps_arg_cache_limit >= i + sizeof(struct pargs)) {
  582                 bcopy(imgp->stringbase, newargs->ar_args, i);
  583                 p->p_args = newargs;
  584                 newargs = NULL;
  585         }
  586         PROC_UNLOCK(p);
  587 
  588         /* Set values passed into the program in registers. */
  589         if (p->p_sysent->sv_setregs)
  590                 (*p->p_sysent->sv_setregs)(td, imgp->entry_addr,
  591                     (u_long)(uintptr_t)stack_base, imgp->ps_strings);
  592         else
  593                 exec_setregs(td, imgp->entry_addr,
  594                     (u_long)(uintptr_t)stack_base, imgp->ps_strings);
  595 
  596 done1:
  597         /*
  598          * Free any resources malloc'd earlier that we didn't use.
  599          */
  600         uifree(euip);
  601         if (newcred == NULL)
  602                 crfree(oldcred);
  603         else
  604                 crfree(newcred);
  605         /*
  606          * Handle deferred decrement of ref counts.
  607          */
  608         if (textvp != NULL)
  609                 vrele(textvp);
  610         if (ndp->ni_vp && error != 0)
  611                 vrele(ndp->ni_vp);
  612 #ifdef KTRACE
  613         if (tracevp != NULL)
  614                 vrele(tracevp);
  615 #endif
  616         if (oldargs != NULL)
  617                 pargs_drop(oldargs);
  618         if (newargs != NULL)
  619                 pargs_drop(newargs);
  620 
  621 exec_fail_dealloc:
  622 
  623         /*
  624          * free various allocated resources
  625          */
  626         if (imgp->firstpage)
  627                 exec_unmap_first_page(imgp);
  628 
  629         if (imgp->vp) {
  630                 NDFREE(ndp, NDF_ONLY_PNBUF);
  631                 vput(imgp->vp);
  632         }
  633 
  634         if (imgp->stringbase != NULL)
  635                 kmem_free_wakeup(exec_map, (vm_offset_t)imgp->stringbase,
  636                     ARG_MAX + PAGE_SIZE);
  637 
  638         if (imgp->object)
  639                 vm_object_deallocate(imgp->object);
  640 
  641         if (error == 0) {
  642                 /*
  643                  * Stop the process here if its stop event mask has
  644                  * the S_EXEC bit set.
  645                  */
  646                 STOPEVENT(p, S_EXEC, 0);
  647                 goto done2;
  648         }
  649 
  650 exec_fail:
  651         /* we're done here, clear P_INEXEC */
  652         PROC_LOCK(p);
  653         p->p_flag &= ~P_INEXEC;
  654         PROC_UNLOCK(p);
  655         
  656         if (imgp->vmspace_destroyed) {
  657                 /* sorry, no more process anymore. exit gracefully */
  658 #ifdef MAC
  659                 mac_execve_exit(imgp);
  660                 if (interplabelvalid)
  661                         mac_destroy_vnode_label(&interplabel);
  662 #endif
  663                 exit1(td, W_EXITCODE(0, SIGABRT));
  664                 /* NOT REACHED */
  665                 error = 0;
  666         }
  667 done2:
  668 #ifdef MAC
  669         mac_execve_exit(imgp);
  670         if (interplabelvalid)
  671                 mac_destroy_vnode_label(&interplabel);
  672 #endif
  673         mtx_unlock(&Giant);
  674         return (error);
  675 }
  676 
  677 #ifndef _SYS_SYSPROTO_H_
  678 struct execve_args {
  679         char    *fname; 
  680         char    **argv;
  681         char    **envv; 
  682 };
  683 #endif
  684 
  685 /*
  686  * MPSAFE
  687  */
  688 int
  689 execve(td, uap)
  690         struct thread *td;
  691         struct execve_args /* {
  692                 char *fname;
  693                 char **argv;
  694                 char **envv;
  695         } */ *uap;
  696 {
  697 
  698         return (kern_execve(td, uap->fname, uap->argv, uap->envv, NULL));
  699 }
  700 
  701 #ifndef _SYS_SYSPROTO_H_
  702 struct __mac_execve_args {
  703         char    *fname;
  704         char    **argv;
  705         char    **envv;
  706         struct mac      *mac_p;
  707 };
  708 #endif
  709 
  710 /*
  711  * MPSAFE
  712  */
  713 int
  714 __mac_execve(td, uap)
  715         struct thread *td;
  716         struct __mac_execve_args /* {
  717                 char *fname;
  718                 char **argv;
  719                 char **envv;
  720                 struct mac *mac_p;
  721         } */ *uap;
  722 {
  723 
  724 #ifdef MAC
  725         return (kern_execve(td, uap->fname, uap->argv, uap->envv,
  726             uap->mac_p));
  727 #else
  728         return (ENOSYS);
  729 #endif
  730 }
  731 
  732 int
  733 exec_map_first_page(imgp)
  734         struct image_params *imgp;
  735 {
  736         int rv, i;
  737         int initial_pagein;
  738         vm_page_t ma[VM_INITIAL_PAGEIN];
  739         vm_object_t object;
  740 
  741         GIANT_REQUIRED;
  742 
  743         if (imgp->firstpage) {
  744                 exec_unmap_first_page(imgp);
  745         }
  746 
  747         VOP_GETVOBJECT(imgp->vp, &object);
  748 
  749         ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY);
  750 
  751         if ((ma[0]->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) {
  752                 initial_pagein = VM_INITIAL_PAGEIN;
  753                 if (initial_pagein > object->size)
  754                         initial_pagein = object->size;
  755                 for (i = 1; i < initial_pagein; i++) {
  756                         if ((ma[i] = vm_page_lookup(object, i)) != NULL) {
  757                                 if ((ma[i]->flags & PG_BUSY) || ma[i]->busy)
  758                                         break;
  759                                 if (ma[i]->valid)
  760                                         break;
  761                                 vm_page_busy(ma[i]);
  762                         } else {
  763                                 ma[i] = vm_page_alloc(object, i,
  764                                     VM_ALLOC_NORMAL);
  765                                 if (ma[i] == NULL)
  766                                         break;
  767                         }
  768                 }
  769                 initial_pagein = i;
  770 
  771                 rv = vm_pager_get_pages(object, ma, initial_pagein, 0);
  772                 ma[0] = vm_page_lookup(object, 0);
  773 
  774                 if ((rv != VM_PAGER_OK) || (ma[0] == NULL) ||
  775                     (ma[0]->valid == 0)) {
  776                         if (ma[0]) {
  777                                 vm_page_lock_queues();
  778                                 pmap_remove_all(ma[0]);
  779                                 vm_page_free(ma[0]);
  780                                 vm_page_unlock_queues();
  781                         }
  782                         return (EIO);
  783                 }
  784         }
  785         vm_page_lock_queues();
  786         vm_page_wire(ma[0]);
  787         vm_page_wakeup(ma[0]);
  788         vm_page_unlock_queues();
  789 
  790         pmap_qenter((vm_offset_t)imgp->image_header, ma, 1);
  791         imgp->firstpage = ma[0];
  792 
  793         return (0);
  794 }
  795 
  796 void
  797 exec_unmap_first_page(imgp)
  798         struct image_params *imgp;
  799 {
  800         GIANT_REQUIRED;
  801 
  802         if (imgp->firstpage) {
  803                 pmap_qremove((vm_offset_t)imgp->image_header, 1);
  804                 vm_page_lock_queues();
  805                 vm_page_unwire(imgp->firstpage, 1);
  806                 vm_page_unlock_queues();
  807                 imgp->firstpage = NULL;
  808         }
  809 }
  810 
  811 /*
  812  * Destroy old address space, and allocate a new stack
  813  *      The new stack is only SGROWSIZ large because it is grown
  814  *      automatically in trap.c.
  815  */
  816 int
  817 exec_new_vmspace(imgp, sv)
  818         struct image_params *imgp;
  819         struct sysentvec *sv;
  820 {
  821         int error;
  822         struct execlist *ep;
  823         struct proc *p = imgp->proc;
  824         struct vmspace *vmspace = p->p_vmspace;
  825         vm_offset_t stack_addr;
  826         vm_map_t map;
  827 
  828         GIANT_REQUIRED;
  829 
  830         stack_addr = sv->sv_usrstack - maxssiz;
  831 
  832         imgp->vmspace_destroyed = 1;
  833 
  834         /*
  835          * Perform functions registered with at_exec().
  836          */
  837         TAILQ_FOREACH(ep, &exec_list, next)
  838                 (*ep->function)(p);
  839 
  840         /*
  841          * Blow away entire process VM, if address space not shared,
  842          * otherwise, create a new VM space so that other threads are
  843          * not disrupted
  844          */
  845         map = &vmspace->vm_map;
  846         if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv->sv_minuser &&
  847             vm_map_max(map) == sv->sv_maxuser) {
  848                 if (vmspace->vm_shm)
  849                         shmexit(p);
  850                 vm_page_lock_queues();
  851                 pmap_remove_pages(vmspace_pmap(vmspace), vm_map_min(map),
  852                     vm_map_max(map));
  853                 vm_page_unlock_queues();
  854                 vm_map_remove(map, vm_map_min(map), vm_map_max(map));
  855         } else {
  856                 vmspace_exec(p, sv->sv_minuser, sv->sv_maxuser);
  857                 vmspace = p->p_vmspace;
  858                 map = &vmspace->vm_map;
  859         }
  860 
  861         /* Allocate a new stack */
  862         error = vm_map_stack(map, stack_addr, (vm_size_t)maxssiz,
  863             sv->sv_stackprot, VM_PROT_ALL, 0);
  864         if (error)
  865                 return (error);
  866 
  867 #ifdef __ia64__
  868         {
  869                 /*
  870                  * Allocate backing store. We really need something
  871                  * similar to vm_map_stack which can allow the backing 
  872                  * store to grow upwards. This will do for now.
  873                  */
  874                 vm_offset_t bsaddr;
  875                 bsaddr = p->p_sysent->sv_usrstack - 2 * maxssiz;
  876                 error = vm_map_find(map, 0, 0, &bsaddr,
  877                     regstkpages * PAGE_SIZE, 0, VM_PROT_ALL, VM_PROT_ALL, 0);
  878                 FIRST_THREAD_IN_PROC(p)->td_md.md_bspstore = bsaddr;
  879         }
  880 #endif
  881 
  882         /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the
  883          * VM_STACK case, but they are still used to monitor the size of the
  884          * process stack so we can check the stack rlimit.
  885          */
  886         vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT;
  887         vmspace->vm_maxsaddr = (char *)sv->sv_usrstack - maxssiz;
  888 
  889         return (0);
  890 }
  891 
  892 /*
  893  * Copy out argument and environment strings from the old process
  894  *      address space into the temporary string buffer.
  895  */
  896 int
  897 exec_extract_strings(imgp)
  898         struct image_params *imgp;
  899 {
  900         char    **argv, **envv;
  901         char    *argp, *envp;
  902         int     error;
  903         size_t  length;
  904 
  905         /*
  906          * extract arguments first
  907          */
  908 
  909         argv = imgp->userspace_argv;
  910 
  911         if (argv) {
  912                 argp = (caddr_t)(intptr_t)fuword(argv);
  913                 if (argp == (caddr_t)-1)
  914                         return (EFAULT);
  915                 if (argp)
  916                         argv++;
  917                 if (imgp->argv0)
  918                         argp = imgp->argv0;
  919                 if (argp) {
  920                         do {
  921                                 if (argp == (caddr_t)-1)
  922                                         return (EFAULT);
  923                                 if ((error = copyinstr(argp, imgp->stringp,
  924                                     imgp->stringspace, &length))) {
  925                                         if (error == ENAMETOOLONG)
  926                                                 return (E2BIG);
  927                                         return (error);
  928                                 }
  929                                 imgp->stringspace -= length;
  930                                 imgp->stringp += length;
  931                                 imgp->argc++;
  932                         } while ((argp = (caddr_t)(intptr_t)fuword(argv++)));
  933                 }
  934         }       
  935 
  936         imgp->endargs = imgp->stringp;
  937 
  938         /*
  939          * extract environment strings
  940          */
  941 
  942         envv = imgp->userspace_envv;
  943 
  944         if (envv) {
  945                 while ((envp = (caddr_t)(intptr_t)fuword(envv++))) {
  946                         if (envp == (caddr_t)-1)
  947                                 return (EFAULT);
  948                         if ((error = copyinstr(envp, imgp->stringp,
  949                             imgp->stringspace, &length))) {
  950                                 if (error == ENAMETOOLONG)
  951                                         return (E2BIG);
  952                                 return (error);
  953                         }
  954                         imgp->stringspace -= length;
  955                         imgp->stringp += length;
  956                         imgp->envc++;
  957                 }
  958         }
  959 
  960         return (0);
  961 }
  962 
  963 /*
  964  * Copy strings out to the new process address space, constructing
  965  *      new arg and env vector tables. Return a pointer to the base
  966  *      so that it can be used as the initial stack pointer.
  967  */
  968 register_t *
  969 exec_copyout_strings(imgp)
  970         struct image_params *imgp;
  971 {
  972         int argc, envc;
  973         char **vectp;
  974         char *stringp, *destp;
  975         register_t *stack_base;
  976         struct ps_strings *arginfo;
  977         struct proc *p;
  978         int szsigcode;
  979 
  980         /*
  981          * Calculate string base and vector table pointers.
  982          * Also deal with signal trampoline code for this exec type.
  983          */
  984         p = imgp->proc;
  985         szsigcode = 0;
  986         arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings;
  987         if (p->p_sysent->sv_szsigcode != NULL)
  988                 szsigcode = *(p->p_sysent->sv_szsigcode);
  989         destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE -
  990             roundup((ARG_MAX - imgp->stringspace), sizeof(char *));
  991 
  992         /*
  993          * install sigcode
  994          */
  995         if (szsigcode)
  996                 copyout(p->p_sysent->sv_sigcode, ((caddr_t)arginfo -
  997                     szsigcode), szsigcode);
  998 
  999         /*
 1000          * If we have a valid auxargs ptr, prepare some room
 1001          * on the stack.
 1002          */
 1003         if (imgp->auxargs) {
 1004                 /*
 1005                  * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for
 1006                  * lower compatibility.
 1007                  */
 1008                 imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size :
 1009                     (AT_COUNT * 2);
 1010                 /*
 1011                  * The '+ 2' is for the null pointers at the end of each of
 1012                  * the arg and env vector sets,and imgp->auxarg_size is room
 1013                  * for argument of Runtime loader.
 1014                  */
 1015                 vectp = (char **)(destp - (imgp->argc + imgp->envc + 2 +
 1016                     imgp->auxarg_size) * sizeof(char *));
 1017 
 1018         } else 
 1019                 /*
 1020                  * The '+ 2' is for the null pointers at the end of each of
 1021                  * the arg and env vector sets
 1022                  */
 1023                 vectp = (char **)(destp - (imgp->argc + imgp->envc + 2) *
 1024                     sizeof(char *));
 1025 
 1026         /*
 1027          * vectp also becomes our initial stack base
 1028          */
 1029         stack_base = (register_t *)vectp;
 1030 
 1031         stringp = imgp->stringbase;
 1032         argc = imgp->argc;
 1033         envc = imgp->envc;
 1034 
 1035         /*
 1036          * Copy out strings - arguments and environment.
 1037          */
 1038         copyout(stringp, destp, ARG_MAX - imgp->stringspace);
 1039 
 1040         /*
 1041          * Fill in "ps_strings" struct for ps, w, etc.
 1042          */
 1043         suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp);
 1044         suword(&arginfo->ps_nargvstr, argc);
 1045 
 1046         /*
 1047          * Fill in argument portion of vector table.
 1048          */
 1049         for (; argc > 0; --argc) {
 1050                 suword(vectp++, (long)(intptr_t)destp);
 1051                 while (*stringp++ != 0)
 1052                         destp++;
 1053                 destp++;
 1054         }
 1055 
 1056         /* a null vector table pointer separates the argp's from the envp's */
 1057         suword(vectp++, 0);
 1058 
 1059         suword(&arginfo->ps_envstr, (long)(intptr_t)vectp);
 1060         suword(&arginfo->ps_nenvstr, envc);
 1061 
 1062         /*
 1063          * Fill in environment portion of vector table.
 1064          */
 1065         for (; envc > 0; --envc) {
 1066                 suword(vectp++, (long)(intptr_t)destp);
 1067                 while (*stringp++ != 0)
 1068                         destp++;
 1069                 destp++;
 1070         }
 1071 
 1072         /* end of vector table is a null pointer */
 1073         suword(vectp, 0);
 1074 
 1075         return (stack_base);
 1076 }
 1077 
 1078 /*
 1079  * Check permissions of file to execute.
 1080  *      Called with imgp->vp locked.
 1081  *      Return 0 for success or error code on failure.
 1082  */
 1083 int
 1084 exec_check_permissions(imgp)
 1085         struct image_params *imgp;
 1086 {
 1087         struct vnode *vp = imgp->vp;
 1088         struct vattr *attr = imgp->attr;
 1089         struct thread *td;
 1090         int error;
 1091 
 1092         td = curthread;                 /* XXXKSE */
 1093 
 1094 #ifdef MAC
 1095         error = mac_check_vnode_exec(td->td_ucred, imgp->vp, imgp);
 1096         if (error)
 1097                 return (error);
 1098 #endif
 1099         
 1100         /* Get file attributes */
 1101         error = VOP_GETATTR(vp, attr, td->td_ucred, td);
 1102         if (error)
 1103                 return (error);
 1104 
 1105         /*
 1106          * 1) Check if file execution is disabled for the filesystem that this
 1107          *      file resides on.
 1108          * 2) Insure that at least one execute bit is on - otherwise root
 1109          *      will always succeed, and we don't want to happen unless the
 1110          *      file really is executable.
 1111          * 3) Insure that the file is a regular file.
 1112          */
 1113         if ((vp->v_mount->mnt_flag & MNT_NOEXEC) ||
 1114             ((attr->va_mode & 0111) == 0) ||
 1115             (attr->va_type != VREG))
 1116                 return (EACCES);
 1117 
 1118         /*
 1119          * Zero length files can't be exec'd
 1120          */
 1121         if (attr->va_size == 0)
 1122                 return (ENOEXEC);
 1123 
 1124         /*
 1125          *  Check for execute permission to file based on current credentials.
 1126          */
 1127         error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td);
 1128         if (error)
 1129                 return (error);
 1130 
 1131         /*
 1132          * Check number of open-for-writes on the file and deny execution
 1133          * if there are any.
 1134          */
 1135         if (vp->v_writecount)
 1136                 return (ETXTBSY);
 1137 
 1138         /*
 1139          * Call filesystem specific open routine (which does nothing in the
 1140          * general case).
 1141          */
 1142         error = VOP_OPEN(vp, FREAD, td->td_ucred, td);
 1143         return (error);
 1144 }
 1145 
 1146 /*
 1147  * Exec handler registration
 1148  */
 1149 int
 1150 exec_register(execsw_arg)
 1151         const struct execsw *execsw_arg;
 1152 {
 1153         const struct execsw **es, **xs, **newexecsw;
 1154         int count = 2;  /* New slot and trailing NULL */
 1155 
 1156         if (execsw)
 1157                 for (es = execsw; *es; es++)
 1158                         count++;
 1159         newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK);
 1160         if (newexecsw == NULL)
 1161                 return (ENOMEM);
 1162         xs = newexecsw;
 1163         if (execsw)
 1164                 for (es = execsw; *es; es++)
 1165                         *xs++ = *es;
 1166         *xs++ = execsw_arg;
 1167         *xs = NULL;
 1168         if (execsw)
 1169                 free(execsw, M_TEMP);
 1170         execsw = newexecsw;
 1171         return (0);
 1172 }
 1173 
 1174 int
 1175 exec_unregister(execsw_arg)
 1176         const struct execsw *execsw_arg;
 1177 {
 1178         const struct execsw **es, **xs, **newexecsw;
 1179         int count = 1;
 1180 
 1181         if (execsw == NULL)
 1182                 panic("unregister with no handlers left?\n");
 1183 
 1184         for (es = execsw; *es; es++) {
 1185                 if (*es == execsw_arg)
 1186                         break;
 1187         }
 1188         if (*es == NULL)
 1189                 return (ENOENT);
 1190         for (es = execsw; *es; es++)
 1191                 if (*es != execsw_arg)
 1192                         count++;
 1193         newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK);
 1194         if (newexecsw == NULL)
 1195                 return (ENOMEM);
 1196         xs = newexecsw;
 1197         for (es = execsw; *es; es++)
 1198                 if (*es != execsw_arg)
 1199                         *xs++ = *es;
 1200         *xs = NULL;
 1201         if (execsw)
 1202                 free(execsw, M_TEMP);
 1203         execsw = newexecsw;
 1204         return (0);
 1205 }
 1206 
 1207 int
 1208 at_exec(function)
 1209         execlist_fn function;
 1210 {
 1211         struct execlist *ep;
 1212 
 1213 #ifdef INVARIANTS
 1214         /* Be noisy if the programmer has lost track of things */
 1215         if (rm_at_exec(function)) 
 1216                 printf("WARNING: exec callout entry (%p) already present\n",
 1217                     function);
 1218 #endif
 1219         ep = malloc(sizeof(*ep), M_ATEXEC, M_NOWAIT);
 1220         if (ep == NULL)
 1221                 return (ENOMEM);
 1222         ep->function = function;
 1223         TAILQ_INSERT_TAIL(&exec_list, ep, next);
 1224         return (0);
 1225 }
 1226 
 1227 /*
 1228  * Scan the exec callout list for the given item and remove it.
 1229  * Returns the number of items removed (0 or 1)
 1230  */
 1231 int
 1232 rm_at_exec(function)
 1233         execlist_fn function;
 1234 {
 1235         struct execlist *ep;
 1236 
 1237         TAILQ_FOREACH(ep, &exec_list, next) {
 1238                 if (ep->function == function) {
 1239                         TAILQ_REMOVE(&exec_list, ep, next);
 1240                         free(ep, M_ATEXEC);
 1241                         return (1);
 1242                 }
 1243         }       
 1244         return (0);
 1245 }

Cache object: 4a1c9cee7c836964461d520c5bff923c


[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]


This page is part of the FreeBSD/Linux Linux Kernel Cross-Reference, and was automatically generated using a modified version of the LXR engine.