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         .sv_size        = SYS_MAXSYSCALL,
   60         .sv_table       = sysent,
   61         .sv_mask        = 0,
   62         .sv_sigsize     = 0,
   63         .sv_sigtbl      = NULL,
   64         .sv_errsize     = 0,
   65         .sv_errtbl      = NULL,
   66         .sv_transtrap   = NULL,
   67         .sv_fixup       = aout_fixup,
   68         .sv_sendsig     = sendsig,
   69         .sv_sigcode     = sigcode,
   70         .sv_szsigcode   = &szsigcode,
   71         .sv_prepsyscall = NULL,
   72         .sv_name        = "FreeBSD a.out",
   73         .sv_coredump    = NULL,
   74         .sv_imgact_try  = NULL,
   75         .sv_minsigstksz = MINSIGSTKSZ,
   76         .sv_pagesize    = PAGE_SIZE,
   77         .sv_minuser     = VM_MIN_ADDRESS,
   78         .sv_maxuser     = VM_MAXUSER_ADDRESS,
   79         .sv_usrstack    = USRSTACK,
   80         .sv_psstrings   = PS_STRINGS,
   81         .sv_stackprot   = VM_PROT_ALL,
   82         .sv_copyout_strings     = exec_copyout_strings,
   83         .sv_setregs     = exec_setregs,
   84         .sv_fixlimit    = NULL,
   85         .sv_maxssiz     = NULL,
   86         .sv_flags       = SV_ABI_FREEBSD | SV_AOUT |
   87 #if defined(__i386__)
   88         SV_IA32 | SV_ILP32
   89 #else
   90 #error Choose SV_XXX flags for the platform
   91 #endif
   92         ,
   93         .sv_set_syscall_retval = cpu_set_syscall_retval,
   94         .sv_fetch_syscall_args = cpu_fetch_syscall_args,
   95         .sv_syscallnames = syscallnames,
   96         .sv_schedtail   = NULL,
   97 };
   98 
   99 static int
  100 aout_fixup(stack_base, imgp)
  101         register_t **stack_base;
  102         struct image_params *imgp;
  103 {
  104 
  105         return (suword(--(*stack_base), imgp->args->argc));
  106 }
  107 
  108 static int
  109 exec_aout_imgact(imgp)
  110         struct image_params *imgp;
  111 {
  112         const struct exec *a_out = (const struct exec *) imgp->image_header;
  113         struct vmspace *vmspace;
  114         vm_map_t map;
  115         vm_object_t object;
  116         vm_offset_t text_end, data_end;
  117         unsigned long virtual_offset;
  118         unsigned long file_offset;
  119         unsigned long bss_size;
  120         int error;
  121 
  122         /*
  123          * Linux and *BSD binaries look very much alike,
  124          * only the machine id is different:
  125          * 0x64 for Linux, 0x86 for *BSD, 0x00 for BSDI.
  126          * NetBSD is in network byte order.. ugh.
  127          */
  128         if (((a_out->a_magic >> 16) & 0xff) != 0x86 &&
  129             ((a_out->a_magic >> 16) & 0xff) != 0 &&
  130             ((((int)ntohl(a_out->a_magic)) >> 16) & 0xff) != 0x86)
  131                 return -1;
  132 
  133         /*
  134          * Set file/virtual offset based on a.out variant.
  135          *      We do two cases: host byte order and network byte order
  136          *      (for NetBSD compatibility)
  137          */
  138         switch ((int)(a_out->a_magic & 0xffff)) {
  139         case ZMAGIC:
  140                 virtual_offset = 0;
  141                 if (a_out->a_text) {
  142                         file_offset = PAGE_SIZE;
  143                 } else {
  144                         /* Bill's "screwball mode" */
  145                         file_offset = 0;
  146                 }
  147                 break;
  148         case QMAGIC:
  149                 virtual_offset = PAGE_SIZE;
  150                 file_offset = 0;
  151                 /* Pass PS_STRINGS for BSD/OS binaries only. */
  152                 if (N_GETMID(*a_out) == MID_ZERO)
  153                         imgp->ps_strings = aout_sysvec.sv_psstrings;
  154                 break;
  155         default:
  156                 /* NetBSD compatibility */
  157                 switch ((int)(ntohl(a_out->a_magic) & 0xffff)) {
  158                 case ZMAGIC:
  159                 case QMAGIC:
  160                         virtual_offset = PAGE_SIZE;
  161                         file_offset = 0;
  162                         break;
  163                 default:
  164                         return (-1);
  165                 }
  166         }
  167 
  168         bss_size = roundup(a_out->a_bss, PAGE_SIZE);
  169 
  170         /*
  171          * Check various fields in header for validity/bounds.
  172          */
  173         if (/* entry point must lay with text region */
  174             a_out->a_entry < virtual_offset ||
  175             a_out->a_entry >= virtual_offset + a_out->a_text ||
  176 
  177             /* text and data size must each be page rounded */
  178             a_out->a_text & PAGE_MASK || a_out->a_data & PAGE_MASK)
  179                 return (-1);
  180 
  181         /* text + data can't exceed file size */
  182         if (a_out->a_data + a_out->a_text > imgp->attr->va_size)
  183                 return (EFAULT);
  184 
  185         /*
  186          * text/data/bss must not exceed limits
  187          */
  188         PROC_LOCK(imgp->proc);
  189         if (/* text can't exceed maximum text size */
  190             a_out->a_text > maxtsiz ||
  191 
  192             /* data + bss can't exceed rlimit */
  193             a_out->a_data + bss_size > lim_cur(imgp->proc, RLIMIT_DATA)) {
  194                         PROC_UNLOCK(imgp->proc);
  195                         return (ENOMEM);
  196         }
  197         PROC_UNLOCK(imgp->proc);
  198 
  199         /*
  200          * Avoid a possible deadlock if the current address space is destroyed
  201          * and that address space maps the locked vnode.  In the common case,
  202          * the locked vnode's v_usecount is decremented but remains greater
  203          * than zero.  Consequently, the vnode lock is not needed by vrele().
  204          * However, in cases where the vnode lock is external, such as nullfs,
  205          * v_usecount may become zero.
  206          */
  207         VOP_UNLOCK(imgp->vp, 0);
  208 
  209         /*
  210          * Destroy old process VM and create a new one (with a new stack)
  211          */
  212         error = exec_new_vmspace(imgp, &aout_sysvec);
  213 
  214         vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY);
  215         if (error)
  216                 return (error);
  217 
  218         /*
  219          * The vm space can be changed by exec_new_vmspace
  220          */
  221         vmspace = imgp->proc->p_vmspace;
  222 
  223         object = imgp->object;
  224         map = &vmspace->vm_map;
  225         vm_map_lock(map);
  226         vm_object_reference(object);
  227 
  228         text_end = virtual_offset + a_out->a_text;
  229         error = vm_map_insert(map, object,
  230                 file_offset,
  231                 virtual_offset, text_end,
  232                 VM_PROT_READ | VM_PROT_EXECUTE, 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         data_end = text_end + a_out->a_data;
  240         if (a_out->a_data) {
  241                 vm_object_reference(object);
  242                 error = vm_map_insert(map, object,
  243                         file_offset + a_out->a_text,
  244                         text_end, data_end,
  245                         VM_PROT_ALL, VM_PROT_ALL,
  246                         MAP_COPY_ON_WRITE | MAP_PREFAULT);
  247                 if (error) {
  248                         vm_map_unlock(map);
  249                         vm_object_deallocate(object);
  250                         return (error);
  251                 }
  252         }
  253 
  254         if (bss_size) {
  255                 error = vm_map_insert(map, NULL, 0,
  256                         data_end, data_end + bss_size,
  257                         VM_PROT_ALL, VM_PROT_ALL, 0);
  258                 if (error) {
  259                         vm_map_unlock(map);
  260                         return (error);
  261                 }
  262         }
  263         vm_map_unlock(map);
  264 
  265         /* Fill in process VM information */
  266         vmspace->vm_tsize = a_out->a_text >> PAGE_SHIFT;
  267         vmspace->vm_dsize = (a_out->a_data + bss_size) >> PAGE_SHIFT;
  268         vmspace->vm_taddr = (caddr_t) (uintptr_t) virtual_offset;
  269         vmspace->vm_daddr = (caddr_t) (uintptr_t)
  270                             (virtual_offset + a_out->a_text);
  271 
  272         /* Fill in image_params */
  273         imgp->interpreted = 0;
  274         imgp->entry_addr = a_out->a_entry;
  275 
  276         imgp->proc->p_sysent = &aout_sysvec;
  277 
  278         return (0);
  279 }
  280 
  281 /*
  282  * Tell kern_execve.c about it, with a little help from the linker.
  283  */
  284 static struct execsw aout_execsw = { exec_aout_imgact, "a.out" };
  285 EXEC_SET(aout, aout_execsw);

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