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  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
    3  *
    4  * Copyright (c) 1993, David Greenman
    5  * All rights reserved.
    6  *
    7  * Redistribution and use in source and binary forms, with or without
    8  * modification, are permitted provided that the following conditions
    9  * are met:
   10  * 1. Redistributions of source code must retain the above copyright
   11  *    notice, this list of conditions and the following disclaimer.
   12  * 2. Redistributions in binary form must reproduce the above copyright
   13  *    notice, this list of conditions and the following disclaimer in the
   14  *    documentation and/or other materials provided with the distribution.
   15  *
   16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   26  * SUCH DAMAGE.
   27  */
   28 
   29 #include <sys/cdefs.h>
   30 __FBSDID("$FreeBSD$");
   31 
   32 #include <sys/param.h>
   33 #include <sys/exec.h>
   34 #include <sys/imgact.h>
   35 #include <sys/imgact_aout.h>
   36 #include <sys/kernel.h>
   37 #include <sys/limits.h>
   38 #include <sys/lock.h>
   39 #include <sys/malloc.h>
   40 #include <sys/mutex.h>
   41 #include <sys/proc.h>
   42 #include <sys/racct.h>
   43 #include <sys/resourcevar.h>
   44 #include <sys/signalvar.h>
   45 #include <sys/syscall.h>
   46 #include <sys/sysent.h>
   47 #include <sys/systm.h>
   48 #include <sys/vnode.h>
   49 
   50 #include <machine/frame.h>
   51 #include <machine/md_var.h>
   52 
   53 #include <vm/vm.h>
   54 #include <vm/pmap.h>
   55 #include <vm/vm_map.h>
   56 #include <vm/vm_object.h>
   57 #include <vm/vm_param.h>
   58 
   59 #ifdef __amd64__
   60 #include <compat/freebsd32/freebsd32_signal.h>
   61 #include <compat/freebsd32/freebsd32_util.h>
   62 #include <compat/freebsd32/freebsd32_proto.h>
   63 #include <compat/freebsd32/freebsd32_syscall.h>
   64 #include <compat/ia32/ia32_signal.h>
   65 #endif
   66 
   67 static int      exec_aout_imgact(struct image_params *imgp);
   68 static int      aout_fixup(register_t **stack_base, struct image_params *imgp);
   69 
   70 #define AOUT32_USRSTACK         0xbfc00000
   71 
   72 #if defined(__i386__)
   73 
   74 #define AOUT32_PS_STRINGS       (AOUT32_USRSTACK - sizeof(struct ps_strings))
   75 
   76 struct sysentvec aout_sysvec = {
   77         .sv_size        = SYS_MAXSYSCALL,
   78         .sv_table       = sysent,
   79         .sv_mask        = 0,
   80         .sv_errsize     = 0,
   81         .sv_errtbl      = NULL,
   82         .sv_transtrap   = NULL,
   83         .sv_fixup       = aout_fixup,
   84         .sv_sendsig     = sendsig,
   85         .sv_sigcode     = sigcode,
   86         .sv_szsigcode   = &szsigcode,
   87         .sv_name        = "FreeBSD a.out",
   88         .sv_coredump    = NULL,
   89         .sv_imgact_try  = NULL,
   90         .sv_minsigstksz = MINSIGSTKSZ,
   91         .sv_minuser     = VM_MIN_ADDRESS,
   92         .sv_maxuser     = AOUT32_USRSTACK,
   93         .sv_usrstack    = AOUT32_USRSTACK,
   94         .sv_psstrings   = AOUT32_PS_STRINGS,
   95         .sv_stackprot   = VM_PROT_ALL,
   96         .sv_copyout_strings     = exec_copyout_strings,
   97         .sv_setregs     = exec_setregs,
   98         .sv_fixlimit    = NULL,
   99         .sv_maxssiz     = NULL,
  100         .sv_flags       = SV_ABI_FREEBSD | SV_AOUT | SV_IA32 | SV_ILP32,
  101         .sv_set_syscall_retval = cpu_set_syscall_retval,
  102         .sv_fetch_syscall_args = cpu_fetch_syscall_args,
  103         .sv_syscallnames = syscallnames,
  104         .sv_schedtail   = NULL,
  105         .sv_thread_detach = NULL,
  106         .sv_trap        = NULL,
  107 };
  108 
  109 #elif defined(__amd64__)
  110 
  111 #define AOUT32_PS_STRINGS \
  112     (AOUT32_USRSTACK - sizeof(struct freebsd32_ps_strings))
  113 #define AOUT32_MINUSER          FREEBSD32_MINUSER
  114 
  115 extern const char *freebsd32_syscallnames[];
  116 extern u_long ia32_maxssiz;
  117 
  118 struct sysentvec aout_sysvec = {
  119         .sv_size        = FREEBSD32_SYS_MAXSYSCALL,
  120         .sv_table       = freebsd32_sysent,
  121         .sv_mask        = 0,
  122         .sv_errsize     = 0,
  123         .sv_errtbl      = NULL,
  124         .sv_transtrap   = NULL,
  125         .sv_fixup       = aout_fixup,
  126         .sv_sendsig     = ia32_sendsig,
  127         .sv_sigcode     = ia32_sigcode,
  128         .sv_szsigcode   = &sz_ia32_sigcode,
  129         .sv_name        = "FreeBSD a.out",
  130         .sv_coredump    = NULL,
  131         .sv_imgact_try  = NULL,
  132         .sv_minsigstksz = MINSIGSTKSZ,
  133         .sv_minuser     = AOUT32_MINUSER,
  134         .sv_maxuser     = AOUT32_USRSTACK,
  135         .sv_usrstack    = AOUT32_USRSTACK,
  136         .sv_psstrings   = AOUT32_PS_STRINGS,
  137         .sv_stackprot   = VM_PROT_ALL,
  138         .sv_copyout_strings     = freebsd32_copyout_strings,
  139         .sv_setregs     = ia32_setregs,
  140         .sv_fixlimit    = ia32_fixlimit,
  141         .sv_maxssiz     = &ia32_maxssiz,
  142         .sv_flags       = SV_ABI_FREEBSD | SV_AOUT | SV_IA32 | SV_ILP32,
  143         .sv_set_syscall_retval = ia32_set_syscall_retval,
  144         .sv_fetch_syscall_args = ia32_fetch_syscall_args,
  145         .sv_syscallnames = freebsd32_syscallnames,
  146 };
  147 #else
  148 #error "Port me"
  149 #endif
  150 
  151 static int
  152 aout_fixup(register_t **stack_base, struct image_params *imgp)
  153 {
  154 
  155         *(char **)stack_base -= sizeof(uint32_t);
  156         return (suword32(*stack_base, imgp->args->argc));
  157 }
  158 
  159 static int
  160 exec_aout_imgact(struct image_params *imgp)
  161 {
  162         const struct exec *a_out = (const struct exec *) imgp->image_header;
  163         struct vmspace *vmspace;
  164         vm_map_t map;
  165         vm_object_t object;
  166         vm_offset_t text_end, data_end;
  167         unsigned long virtual_offset;
  168         unsigned long file_offset;
  169         unsigned long bss_size;
  170         int error;
  171 
  172         /*
  173          * Linux and *BSD binaries look very much alike,
  174          * only the machine id is different:
  175          * 0x64 for Linux, 0x86 for *BSD, 0x00 for BSDI.
  176          * NetBSD is in network byte order.. ugh.
  177          */
  178         if (((a_out->a_midmag >> 16) & 0xff) != 0x86 &&
  179             ((a_out->a_midmag >> 16) & 0xff) != 0 &&
  180             ((((int)ntohl(a_out->a_midmag)) >> 16) & 0xff) != 0x86)
  181                 return -1;
  182 
  183         /*
  184          * Set file/virtual offset based on a.out variant.
  185          *      We do two cases: host byte order and network byte order
  186          *      (for NetBSD compatibility)
  187          */
  188         switch ((int)(a_out->a_midmag & 0xffff)) {
  189         case ZMAGIC:
  190                 virtual_offset = 0;
  191                 if (a_out->a_text) {
  192                         file_offset = PAGE_SIZE;
  193                 } else {
  194                         /* Bill's "screwball mode" */
  195                         file_offset = 0;
  196                 }
  197                 break;
  198         case QMAGIC:
  199                 virtual_offset = PAGE_SIZE;
  200                 file_offset = 0;
  201                 /* Pass PS_STRINGS for BSD/OS binaries only. */
  202                 if (N_GETMID(*a_out) == MID_ZERO)
  203                         imgp->ps_strings = aout_sysvec.sv_psstrings;
  204                 break;
  205         default:
  206                 /* NetBSD compatibility */
  207                 switch ((int)(ntohl(a_out->a_midmag) & 0xffff)) {
  208                 case ZMAGIC:
  209                 case QMAGIC:
  210                         virtual_offset = PAGE_SIZE;
  211                         file_offset = 0;
  212                         break;
  213                 default:
  214                         return (-1);
  215                 }
  216         }
  217 
  218         bss_size = roundup(a_out->a_bss, PAGE_SIZE);
  219 
  220         /*
  221          * Check various fields in header for validity/bounds.
  222          */
  223         if (/* entry point must lay with text region */
  224             a_out->a_entry < virtual_offset ||
  225             a_out->a_entry >= virtual_offset + a_out->a_text ||
  226 
  227             /* text and data size must each be page rounded */
  228             a_out->a_text & PAGE_MASK || a_out->a_data & PAGE_MASK
  229 
  230 #ifdef __amd64__
  231             ||
  232             /* overflows */
  233             virtual_offset + a_out->a_text + a_out->a_data + bss_size > UINT_MAX
  234 #endif
  235             )
  236                 return (-1);
  237 
  238         /* text + data can't exceed file size */
  239         if (a_out->a_data + a_out->a_text > imgp->attr->va_size)
  240                 return (EFAULT);
  241 
  242         /*
  243          * text/data/bss must not exceed limits
  244          */
  245         PROC_LOCK(imgp->proc);
  246         if (/* text can't exceed maximum text size */
  247             a_out->a_text > maxtsiz ||
  248 
  249             /* data + bss can't exceed rlimit */
  250             a_out->a_data + bss_size > lim_cur_proc(imgp->proc, RLIMIT_DATA) ||
  251             racct_set(imgp->proc, RACCT_DATA, a_out->a_data + bss_size) != 0) {
  252                 PROC_UNLOCK(imgp->proc);
  253                 return (ENOMEM);
  254         }
  255         PROC_UNLOCK(imgp->proc);
  256 
  257         /*
  258          * Avoid a possible deadlock if the current address space is destroyed
  259          * and that address space maps the locked vnode.  In the common case,
  260          * the locked vnode's v_usecount is decremented but remains greater
  261          * than zero.  Consequently, the vnode lock is not needed by vrele().
  262          * However, in cases where the vnode lock is external, such as nullfs,
  263          * v_usecount may become zero.
  264          */
  265         VOP_UNLOCK(imgp->vp, 0);
  266 
  267         /*
  268          * Destroy old process VM and create a new one (with a new stack)
  269          */
  270         error = exec_new_vmspace(imgp, &aout_sysvec);
  271 
  272         vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
  273         if (error)
  274                 return (error);
  275 
  276         /*
  277          * The vm space can be changed by exec_new_vmspace
  278          */
  279         vmspace = imgp->proc->p_vmspace;
  280 
  281         object = imgp->object;
  282         map = &vmspace->vm_map;
  283         vm_map_lock(map);
  284         vm_object_reference(object);
  285 
  286         text_end = virtual_offset + a_out->a_text;
  287         error = vm_map_insert(map, object,
  288                 file_offset,
  289                 virtual_offset, text_end,
  290                 VM_PROT_READ | VM_PROT_EXECUTE, VM_PROT_ALL,
  291                 MAP_COPY_ON_WRITE | MAP_PREFAULT | MAP_VN_EXEC);
  292         if (error) {
  293                 vm_map_unlock(map);
  294                 vm_object_deallocate(object);
  295                 return (error);
  296         }
  297         VOP_SET_TEXT_CHECKED(imgp->vp);
  298         data_end = text_end + a_out->a_data;
  299         if (a_out->a_data) {
  300                 vm_object_reference(object);
  301                 error = vm_map_insert(map, object,
  302                         file_offset + a_out->a_text,
  303                         text_end, data_end,
  304                         VM_PROT_ALL, VM_PROT_ALL,
  305                         MAP_COPY_ON_WRITE | MAP_PREFAULT | MAP_VN_EXEC);
  306                 if (error) {
  307                         vm_map_unlock(map);
  308                         vm_object_deallocate(object);
  309                         return (error);
  310                 }
  311                 VOP_SET_TEXT_CHECKED(imgp->vp);
  312         }
  313 
  314         if (bss_size) {
  315                 error = vm_map_insert(map, NULL, 0,
  316                         data_end, data_end + bss_size,
  317                         VM_PROT_ALL, VM_PROT_ALL, 0);
  318                 if (error) {
  319                         vm_map_unlock(map);
  320                         return (error);
  321                 }
  322         }
  323         vm_map_unlock(map);
  324 
  325         /* Fill in process VM information */
  326         vmspace->vm_tsize = a_out->a_text >> PAGE_SHIFT;
  327         vmspace->vm_dsize = (a_out->a_data + bss_size) >> PAGE_SHIFT;
  328         vmspace->vm_taddr = (caddr_t) (uintptr_t) virtual_offset;
  329         vmspace->vm_daddr = (caddr_t) (uintptr_t)
  330                             (virtual_offset + a_out->a_text);
  331 
  332         /* Fill in image_params */
  333         imgp->interpreted = 0;
  334         imgp->entry_addr = a_out->a_entry;
  335 
  336         imgp->proc->p_sysent = &aout_sysvec;
  337 
  338         return (0);
  339 }
  340 
  341 /*
  342  * Tell kern_execve.c about it, with a little help from the linker.
  343  */
  344 static struct execsw aout_execsw = {
  345         .ex_imgact = exec_aout_imgact,
  346         .ex_name = "a.out"
  347 };
  348 EXEC_SET(aout, aout_execsw);

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