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


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FreeBSD/Linux Kernel Cross Reference
sys/kern/imgact_aout.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("$FreeBSD$");
   29 
   30 #include <sys/param.h>
   31 #include <sys/exec.h>
   32 #include <sys/imgact.h>
   33 #include <sys/imgact_aout.h>
   34 #include <sys/kernel.h>
   35 #include <sys/lock.h>
   36 #include <sys/malloc.h>
   37 #include <sys/mutex.h>
   38 #include <sys/proc.h>
   39 #include <sys/resourcevar.h>
   40 #include <sys/signalvar.h>
   41 #include <sys/syscall.h>
   42 #include <sys/sysent.h>
   43 #include <sys/systm.h>
   44 #include <sys/vnode.h>
   45 
   46 #include <machine/frame.h>
   47 #include <machine/md_var.h>
   48 
   49 #include <vm/vm.h>
   50 #include <vm/pmap.h>
   51 #include <vm/vm_map.h>
   52 #include <vm/vm_object.h>
   53 #include <vm/vm_param.h>
   54 
   55 static int      exec_aout_imgact(struct image_params *imgp);
   56 static int      aout_fixup(register_t **stack_base, struct image_params *imgp);
   57 
   58 struct sysentvec aout_sysvec = {
   59         SYS_MAXSYSCALL,
   60         sysent,
   61         0,
   62         0,
   63         NULL,
   64         0,
   65         NULL,
   66         NULL,
   67         aout_fixup,
   68         sendsig,
   69         sigcode,
   70         &szsigcode,
   71         NULL,
   72         "FreeBSD a.out",
   73         NULL,
   74         NULL,
   75         MINSIGSTKSZ,
   76         PAGE_SIZE,
   77         VM_MIN_ADDRESS,
   78         VM_MAXUSER_ADDRESS,
   79         USRSTACK,
   80         PS_STRINGS,
   81         VM_PROT_ALL,
   82         exec_copyout_strings,
   83         exec_setregs,
   84         NULL
   85 };
   86 
   87 static int
   88 aout_fixup(stack_base, imgp)
   89         register_t **stack_base;
   90         struct image_params *imgp;
   91 {
   92 
   93         return (suword(--(*stack_base), imgp->args->argc));
   94 }
   95 
   96 static int
   97 exec_aout_imgact(imgp)
   98         struct image_params *imgp;
   99 {
  100         const struct exec *a_out = (const struct exec *) imgp->image_header;
  101         struct thread *td = curthread;
  102         struct vmspace *vmspace;
  103         vm_map_t map;
  104         vm_object_t object;
  105         vm_offset_t text_end, data_end;
  106         unsigned long virtual_offset;
  107         unsigned long file_offset;
  108         unsigned long bss_size;
  109         int error;
  110 
  111         /*
  112          * Linux and *BSD binaries look very much alike,
  113          * only the machine id is different:
  114          * 0x64 for Linux, 0x86 for *BSD, 0x00 for BSDI.
  115          * NetBSD is in network byte order.. ugh.
  116          */
  117         if (((a_out->a_magic >> 16) & 0xff) != 0x86 &&
  118             ((a_out->a_magic >> 16) & 0xff) != 0 &&
  119             ((((int)ntohl(a_out->a_magic)) >> 16) & 0xff) != 0x86)
  120                 return -1;
  121 
  122         /*
  123          * Set file/virtual offset based on a.out variant.
  124          *      We do two cases: host byte order and network byte order
  125          *      (for NetBSD compatibility)
  126          */
  127         switch ((int)(a_out->a_magic & 0xffff)) {
  128         case ZMAGIC:
  129                 virtual_offset = 0;
  130                 if (a_out->a_text) {
  131                         file_offset = PAGE_SIZE;
  132                 } else {
  133                         /* Bill's "screwball mode" */
  134                         file_offset = 0;
  135                 }
  136                 break;
  137         case QMAGIC:
  138                 virtual_offset = PAGE_SIZE;
  139                 file_offset = 0;
  140                 /* Pass PS_STRINGS for BSD/OS binaries only. */
  141                 if (N_GETMID(*a_out) == MID_ZERO)
  142                         imgp->ps_strings = aout_sysvec.sv_psstrings;
  143                 break;
  144         default:
  145                 /* NetBSD compatibility */
  146                 switch ((int)(ntohl(a_out->a_magic) & 0xffff)) {
  147                 case ZMAGIC:
  148                 case QMAGIC:
  149                         virtual_offset = PAGE_SIZE;
  150                         file_offset = 0;
  151                         break;
  152                 default:
  153                         return (-1);
  154                 }
  155         }
  156 
  157         bss_size = roundup(a_out->a_bss, PAGE_SIZE);
  158 
  159         /*
  160          * Check various fields in header for validity/bounds.
  161          */
  162         if (/* entry point must lay with text region */
  163             a_out->a_entry < virtual_offset ||
  164             a_out->a_entry >= virtual_offset + a_out->a_text ||
  165 
  166             /* text and data size must each be page rounded */
  167             a_out->a_text & PAGE_MASK || a_out->a_data & PAGE_MASK)
  168                 return (-1);
  169 
  170         /* text + data can't exceed file size */
  171         if (a_out->a_data + a_out->a_text > imgp->attr->va_size)
  172                 return (EFAULT);
  173 
  174         /*
  175          * text/data/bss must not exceed limits
  176          */
  177         PROC_LOCK(imgp->proc);
  178         if (/* text can't exceed maximum text size */
  179             a_out->a_text > maxtsiz ||
  180 
  181             /* data + bss can't exceed rlimit */
  182             a_out->a_data + bss_size > lim_cur(imgp->proc, RLIMIT_DATA)) {
  183                         PROC_UNLOCK(imgp->proc);
  184                         return (ENOMEM);
  185         }
  186         PROC_UNLOCK(imgp->proc);
  187 
  188         /*
  189          * Avoid a possible deadlock if the current address space is destroyed
  190          * and that address space maps the locked vnode.  In the common case,
  191          * the locked vnode's v_usecount is decremented but remains greater
  192          * than zero.  Consequently, the vnode lock is not needed by vrele().
  193          * However, in cases where the vnode lock is external, such as nullfs,
  194          * v_usecount may become zero.
  195          */
  196         VOP_UNLOCK(imgp->vp, 0, td);
  197 
  198         /*
  199          * Destroy old process VM and create a new one (with a new stack)
  200          */
  201         exec_new_vmspace(imgp, &aout_sysvec);
  202 
  203         vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY, td);
  204 
  205         /*
  206          * The vm space can be changed by exec_new_vmspace
  207          */
  208         vmspace = imgp->proc->p_vmspace;
  209 
  210         object = imgp->object;
  211         map = &vmspace->vm_map;
  212         vm_map_lock(map);
  213         vm_object_reference(object);
  214 
  215         text_end = virtual_offset + a_out->a_text;
  216         error = vm_map_insert(map, object,
  217                 file_offset,
  218                 virtual_offset, text_end,
  219                 VM_PROT_READ | VM_PROT_EXECUTE, VM_PROT_ALL,
  220                 MAP_COPY_ON_WRITE | MAP_PREFAULT);
  221         if (error) {
  222                 vm_map_unlock(map);
  223                 vm_object_deallocate(object);
  224                 return (error);
  225         }
  226         data_end = text_end + a_out->a_data;
  227         if (a_out->a_data) {
  228                 vm_object_reference(object);
  229                 error = vm_map_insert(map, object,
  230                         file_offset + a_out->a_text,
  231                         text_end, data_end,
  232                         VM_PROT_ALL, VM_PROT_ALL,
  233                         MAP_COPY_ON_WRITE | MAP_PREFAULT);
  234                 if (error) {
  235                         vm_map_unlock(map);
  236                         vm_object_deallocate(object);
  237                         return (error);
  238                 }
  239         }
  240 
  241         if (bss_size) {
  242                 error = vm_map_insert(map, NULL, 0,
  243                         data_end, data_end + bss_size,
  244                         VM_PROT_ALL, VM_PROT_ALL, 0);
  245                 if (error) {
  246                         vm_map_unlock(map);
  247                         return (error);
  248                 }
  249         }
  250         vm_map_unlock(map);
  251 
  252         /* Fill in process VM information */
  253         vmspace->vm_tsize = a_out->a_text >> PAGE_SHIFT;
  254         vmspace->vm_dsize = (a_out->a_data + bss_size) >> PAGE_SHIFT;
  255         vmspace->vm_taddr = (caddr_t) (uintptr_t) virtual_offset;
  256         vmspace->vm_daddr = (caddr_t) (uintptr_t)
  257                             (virtual_offset + a_out->a_text);
  258 
  259         /* Fill in image_params */
  260         imgp->interpreted = 0;
  261         imgp->entry_addr = a_out->a_entry;
  262 
  263         imgp->proc->p_sysent = &aout_sysvec;
  264 
  265         return (0);
  266 }
  267 
  268 /*
  269  * Tell kern_execve.c about it, with a little help from the linker.
  270  */
  271 static struct execsw aout_execsw = { exec_aout_imgact, "a.out" };
  272 EXEC_SET(aout, aout_execsw);

Cache object: b149b06640643a01098c9d2aaa5bb7bd


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