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: releng/11.0/sys/kern/imgact_aout.c 293613 2016-01-09 20:18:53Z dchagin $");
   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/limits.h>
   36 #include <sys/lock.h>
   37 #include <sys/malloc.h>
   38 #include <sys/mutex.h>
   39 #include <sys/proc.h>
   40 #include <sys/racct.h>
   41 #include <sys/resourcevar.h>
   42 #include <sys/signalvar.h>
   43 #include <sys/syscall.h>
   44 #include <sys/sysent.h>
   45 #include <sys/systm.h>
   46 #include <sys/vnode.h>
   47 
   48 #include <machine/frame.h>
   49 #include <machine/md_var.h>
   50 
   51 #include <vm/vm.h>
   52 #include <vm/pmap.h>
   53 #include <vm/vm_map.h>
   54 #include <vm/vm_object.h>
   55 #include <vm/vm_param.h>
   56 
   57 #ifdef __amd64__
   58 #include <compat/freebsd32/freebsd32_signal.h>
   59 #include <compat/freebsd32/freebsd32_util.h>
   60 #include <compat/freebsd32/freebsd32_proto.h>
   61 #include <compat/freebsd32/freebsd32_syscall.h>
   62 #include <compat/ia32/ia32_signal.h>
   63 #endif
   64 
   65 static int      exec_aout_imgact(struct image_params *imgp);
   66 static int      aout_fixup(register_t **stack_base, struct image_params *imgp);
   67 
   68 #if defined(__i386__)
   69 struct sysentvec aout_sysvec = {
   70         .sv_size        = SYS_MAXSYSCALL,
   71         .sv_table       = sysent,
   72         .sv_mask        = 0,
   73         .sv_errsize     = 0,
   74         .sv_errtbl      = NULL,
   75         .sv_transtrap   = NULL,
   76         .sv_fixup       = aout_fixup,
   77         .sv_sendsig     = sendsig,
   78         .sv_sigcode     = sigcode,
   79         .sv_szsigcode   = &szsigcode,
   80         .sv_name        = "FreeBSD a.out",
   81         .sv_coredump    = NULL,
   82         .sv_imgact_try  = NULL,
   83         .sv_minsigstksz = MINSIGSTKSZ,
   84         .sv_pagesize    = PAGE_SIZE,
   85         .sv_minuser     = VM_MIN_ADDRESS,
   86         .sv_maxuser     = VM_MAXUSER_ADDRESS,
   87         .sv_usrstack    = USRSTACK,
   88         .sv_psstrings   = PS_STRINGS,
   89         .sv_stackprot   = VM_PROT_ALL,
   90         .sv_copyout_strings     = exec_copyout_strings,
   91         .sv_setregs     = exec_setregs,
   92         .sv_fixlimit    = NULL,
   93         .sv_maxssiz     = NULL,
   94         .sv_flags       = SV_ABI_FREEBSD | SV_AOUT | SV_IA32 | SV_ILP32,
   95         .sv_set_syscall_retval = cpu_set_syscall_retval,
   96         .sv_fetch_syscall_args = cpu_fetch_syscall_args,
   97         .sv_syscallnames = syscallnames,
   98         .sv_schedtail   = NULL,
   99         .sv_thread_detach = NULL,
  100         .sv_trap        = NULL,
  101 };
  102 
  103 #elif defined(__amd64__)
  104 
  105 #define AOUT32_USRSTACK 0xbfc00000
  106 #define AOUT32_PS_STRINGS \
  107     (AOUT32_USRSTACK - sizeof(struct freebsd32_ps_strings))
  108 #define AOUT32_MINUSER  FREEBSD32_MINUSER
  109 
  110 extern const char *freebsd32_syscallnames[];
  111 extern u_long ia32_maxssiz;
  112 
  113 struct sysentvec aout_sysvec = {
  114         .sv_size        = FREEBSD32_SYS_MAXSYSCALL,
  115         .sv_table       = freebsd32_sysent,
  116         .sv_mask        = 0,
  117         .sv_errsize     = 0,
  118         .sv_errtbl      = NULL,
  119         .sv_transtrap   = NULL,
  120         .sv_fixup       = aout_fixup,
  121         .sv_sendsig     = ia32_sendsig,
  122         .sv_sigcode     = ia32_sigcode,
  123         .sv_szsigcode   = &sz_ia32_sigcode,
  124         .sv_name        = "FreeBSD a.out",
  125         .sv_coredump    = NULL,
  126         .sv_imgact_try  = NULL,
  127         .sv_minsigstksz = MINSIGSTKSZ,
  128         .sv_pagesize    = IA32_PAGE_SIZE,
  129         .sv_minuser     = AOUT32_MINUSER,
  130         .sv_maxuser     = AOUT32_USRSTACK,
  131         .sv_usrstack    = AOUT32_USRSTACK,
  132         .sv_psstrings   = AOUT32_PS_STRINGS,
  133         .sv_stackprot   = VM_PROT_ALL,
  134         .sv_copyout_strings     = freebsd32_copyout_strings,
  135         .sv_setregs     = ia32_setregs,
  136         .sv_fixlimit    = ia32_fixlimit,
  137         .sv_maxssiz     = &ia32_maxssiz,
  138         .sv_flags       = SV_ABI_FREEBSD | SV_AOUT | SV_IA32 | SV_ILP32,
  139         .sv_set_syscall_retval = ia32_set_syscall_retval,
  140         .sv_fetch_syscall_args = ia32_fetch_syscall_args,
  141         .sv_syscallnames = freebsd32_syscallnames,
  142 };
  143 #else
  144 #error "Port me"
  145 #endif
  146 
  147 static int
  148 aout_fixup(register_t **stack_base, struct image_params *imgp)
  149 {
  150 
  151         *(char **)stack_base -= sizeof(uint32_t);
  152         return (suword32(*stack_base, imgp->args->argc));
  153 }
  154 
  155 static int
  156 exec_aout_imgact(struct image_params *imgp)
  157 {
  158         const struct exec *a_out = (const struct exec *) imgp->image_header;
  159         struct vmspace *vmspace;
  160         vm_map_t map;
  161         vm_object_t object;
  162         vm_offset_t text_end, data_end;
  163         unsigned long virtual_offset;
  164         unsigned long file_offset;
  165         unsigned long bss_size;
  166         int error;
  167 
  168         /*
  169          * Linux and *BSD binaries look very much alike,
  170          * only the machine id is different:
  171          * 0x64 for Linux, 0x86 for *BSD, 0x00 for BSDI.
  172          * NetBSD is in network byte order.. ugh.
  173          */
  174         if (((a_out->a_midmag >> 16) & 0xff) != 0x86 &&
  175             ((a_out->a_midmag >> 16) & 0xff) != 0 &&
  176             ((((int)ntohl(a_out->a_midmag)) >> 16) & 0xff) != 0x86)
  177                 return -1;
  178 
  179         /*
  180          * Set file/virtual offset based on a.out variant.
  181          *      We do two cases: host byte order and network byte order
  182          *      (for NetBSD compatibility)
  183          */
  184         switch ((int)(a_out->a_midmag & 0xffff)) {
  185         case ZMAGIC:
  186                 virtual_offset = 0;
  187                 if (a_out->a_text) {
  188                         file_offset = PAGE_SIZE;
  189                 } else {
  190                         /* Bill's "screwball mode" */
  191                         file_offset = 0;
  192                 }
  193                 break;
  194         case QMAGIC:
  195                 virtual_offset = PAGE_SIZE;
  196                 file_offset = 0;
  197                 /* Pass PS_STRINGS for BSD/OS binaries only. */
  198                 if (N_GETMID(*a_out) == MID_ZERO)
  199                         imgp->ps_strings = aout_sysvec.sv_psstrings;
  200                 break;
  201         default:
  202                 /* NetBSD compatibility */
  203                 switch ((int)(ntohl(a_out->a_midmag) & 0xffff)) {
  204                 case ZMAGIC:
  205                 case QMAGIC:
  206                         virtual_offset = PAGE_SIZE;
  207                         file_offset = 0;
  208                         break;
  209                 default:
  210                         return (-1);
  211                 }
  212         }
  213 
  214         bss_size = roundup(a_out->a_bss, PAGE_SIZE);
  215 
  216         /*
  217          * Check various fields in header for validity/bounds.
  218          */
  219         if (/* entry point must lay with text region */
  220             a_out->a_entry < virtual_offset ||
  221             a_out->a_entry >= virtual_offset + a_out->a_text ||
  222 
  223             /* text and data size must each be page rounded */
  224             a_out->a_text & PAGE_MASK || a_out->a_data & PAGE_MASK
  225 
  226 #ifdef __amd64__
  227             ||
  228             /* overflows */
  229             virtual_offset + a_out->a_text + a_out->a_data + bss_size > UINT_MAX
  230 #endif
  231             )
  232                 return (-1);
  233 
  234         /* text + data can't exceed file size */
  235         if (a_out->a_data + a_out->a_text > imgp->attr->va_size)
  236                 return (EFAULT);
  237 
  238         /*
  239          * text/data/bss must not exceed limits
  240          */
  241         PROC_LOCK(imgp->proc);
  242         if (/* text can't exceed maximum text size */
  243             a_out->a_text > maxtsiz ||
  244 
  245             /* data + bss can't exceed rlimit */
  246             a_out->a_data + bss_size > lim_cur_proc(imgp->proc, RLIMIT_DATA) ||
  247             racct_set(imgp->proc, RACCT_DATA, a_out->a_data + bss_size) != 0) {
  248                         PROC_UNLOCK(imgp->proc);
  249                         return (ENOMEM);
  250         }
  251         PROC_UNLOCK(imgp->proc);
  252 
  253         /*
  254          * Avoid a possible deadlock if the current address space is destroyed
  255          * and that address space maps the locked vnode.  In the common case,
  256          * the locked vnode's v_usecount is decremented but remains greater
  257          * than zero.  Consequently, the vnode lock is not needed by vrele().
  258          * However, in cases where the vnode lock is external, such as nullfs,
  259          * v_usecount may become zero.
  260          */
  261         VOP_UNLOCK(imgp->vp, 0);
  262 
  263         /*
  264          * Destroy old process VM and create a new one (with a new stack)
  265          */
  266         error = exec_new_vmspace(imgp, &aout_sysvec);
  267 
  268         vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY);
  269         if (error)
  270                 return (error);
  271 
  272         /*
  273          * The vm space can be changed by exec_new_vmspace
  274          */
  275         vmspace = imgp->proc->p_vmspace;
  276 
  277         object = imgp->object;
  278         map = &vmspace->vm_map;
  279         vm_map_lock(map);
  280         vm_object_reference(object);
  281 
  282         text_end = virtual_offset + a_out->a_text;
  283         error = vm_map_insert(map, object,
  284                 file_offset,
  285                 virtual_offset, text_end,
  286                 VM_PROT_READ | VM_PROT_EXECUTE, VM_PROT_ALL,
  287                 MAP_COPY_ON_WRITE | MAP_PREFAULT);
  288         if (error) {
  289                 vm_map_unlock(map);
  290                 vm_object_deallocate(object);
  291                 return (error);
  292         }
  293         data_end = text_end + a_out->a_data;
  294         if (a_out->a_data) {
  295                 vm_object_reference(object);
  296                 error = vm_map_insert(map, object,
  297                         file_offset + a_out->a_text,
  298                         text_end, data_end,
  299                         VM_PROT_ALL, VM_PROT_ALL,
  300                         MAP_COPY_ON_WRITE | MAP_PREFAULT);
  301                 if (error) {
  302                         vm_map_unlock(map);
  303                         vm_object_deallocate(object);
  304                         return (error);
  305                 }
  306         }
  307 
  308         if (bss_size) {
  309                 error = vm_map_insert(map, NULL, 0,
  310                         data_end, data_end + bss_size,
  311                         VM_PROT_ALL, VM_PROT_ALL, 0);
  312                 if (error) {
  313                         vm_map_unlock(map);
  314                         return (error);
  315                 }
  316         }
  317         vm_map_unlock(map);
  318 
  319         /* Fill in process VM information */
  320         vmspace->vm_tsize = a_out->a_text >> PAGE_SHIFT;
  321         vmspace->vm_dsize = (a_out->a_data + bss_size) >> PAGE_SHIFT;
  322         vmspace->vm_taddr = (caddr_t) (uintptr_t) virtual_offset;
  323         vmspace->vm_daddr = (caddr_t) (uintptr_t)
  324                             (virtual_offset + a_out->a_text);
  325 
  326         /* Fill in image_params */
  327         imgp->interpreted = 0;
  328         imgp->entry_addr = a_out->a_entry;
  329 
  330         imgp->proc->p_sysent = &aout_sysvec;
  331 
  332         return (0);
  333 }
  334 
  335 /*
  336  * Tell kern_execve.c about it, with a little help from the linker.
  337  */
  338 static struct execsw aout_execsw = { exec_aout_imgact, "a.out" };
  339 EXEC_SET(aout, aout_execsw);

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