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/compat/linux/linux_mmap.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) 2004 Tim J. Robbins
    3  * Copyright (c) 2002 Doug Rabson
    4  * Copyright (c) 2000 Marcel Moolenaar
    5  * Copyright (c) 1994-1995 Søren Schmidt
    6  * All rights reserved.
    7  *
    8  * Redistribution and use in source and binary forms, with or without
    9  * modification, are permitted provided that the following conditions
   10  * are met:
   11  * 1. Redistributions of source code must retain the above copyright
   12  *    notice, this list of conditions and the following disclaimer
   13  *    in this position and unchanged.
   14  * 2. Redistributions in binary form must reproduce the above copyright
   15  *    notice, this list of conditions and the following disclaimer in the
   16  *    documentation and/or other materials provided with the distribution.
   17  * 3. The name of the author may not be used to endorse or promote products
   18  *    derived from this software without specific prior written permission.
   19  *
   20  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   21  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   22  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   23  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   24  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   25  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   26  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   27  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   28  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   29  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   30  *
   31  * $FreeBSD: releng/11.1/sys/compat/linux/linux_mmap.c 315556 2017-03-19 15:32:12Z trasz $
   32  */
   33 
   34 #include <sys/cdefs.h>
   35 __FBSDID("$FreeBSD: releng/11.1/sys/compat/linux/linux_mmap.c 315556 2017-03-19 15:32:12Z trasz $");
   36 
   37 #include <sys/capsicum.h>
   38 #include <sys/file.h>
   39 #include <sys/imgact.h>
   40 #include <sys/ktr.h>
   41 #include <sys/mman.h>
   42 #include <sys/proc.h>
   43 #include <sys/resourcevar.h>
   44 #include <sys/syscallsubr.h>
   45 #include <sys/sysent.h>
   46 #include <sys/sysproto.h>
   47 
   48 #include <vm/pmap.h>
   49 #include <vm/vm_extern.h>
   50 #include <vm/vm_map.h>
   51 
   52 #include <compat/linux/linux_emul.h>
   53 #include <compat/linux/linux_mmap.h>
   54 #include <compat/linux/linux_persona.h>
   55 #include <compat/linux/linux_util.h>
   56 
   57 
   58 #define STACK_SIZE  (2 * 1024 * 1024)
   59 #define GUARD_SIZE  (4 * PAGE_SIZE)
   60 
   61 #if defined(__amd64__)
   62 static void linux_fixup_prot(struct thread *td, int *prot);
   63 #endif
   64 
   65 
   66 int
   67 linux_mmap_common(struct thread *td, uintptr_t addr, size_t len, int prot,
   68     int flags, int fd, off_t pos)
   69 {
   70         struct proc *p = td->td_proc;
   71         struct vmspace *vms = td->td_proc->p_vmspace;
   72         int bsd_flags, error;
   73         struct file *fp;
   74 
   75         cap_rights_t rights;
   76         LINUX_CTR6(mmap2, "0x%lx, %ld, %ld, 0x%08lx, %ld, 0x%lx",
   77             addr, len, prot, flags, fd, pos);
   78 
   79         error = 0;
   80         bsd_flags = 0;
   81         fp = NULL;
   82 
   83         /*
   84          * Linux mmap(2):
   85          * You must specify exactly one of MAP_SHARED and MAP_PRIVATE
   86          */
   87         if (!((flags & LINUX_MAP_SHARED) ^ (flags & LINUX_MAP_PRIVATE)))
   88                 return (EINVAL);
   89 
   90         if (flags & LINUX_MAP_SHARED)
   91                 bsd_flags |= MAP_SHARED;
   92         if (flags & LINUX_MAP_PRIVATE)
   93                 bsd_flags |= MAP_PRIVATE;
   94         if (flags & LINUX_MAP_FIXED)
   95                 bsd_flags |= MAP_FIXED;
   96         if (flags & LINUX_MAP_ANON) {
   97                 /* Enforce pos to be on page boundary, then ignore. */
   98                 if ((pos & PAGE_MASK) != 0)
   99                         return (EINVAL);
  100                 pos = 0;
  101                 bsd_flags |= MAP_ANON;
  102         } else
  103                 bsd_flags |= MAP_NOSYNC;
  104         if (flags & LINUX_MAP_GROWSDOWN)
  105                 bsd_flags |= MAP_STACK;
  106 
  107         /*
  108          * PROT_READ, PROT_WRITE, or PROT_EXEC implies PROT_READ and PROT_EXEC
  109          * on Linux/i386 if the binary requires executable stack.
  110          * We do this only for IA32 emulation as on native i386 this is does not
  111          * make sense without PAE.
  112          *
  113          * XXX. Linux checks that the file system is not mounted with noexec.
  114          */
  115 #if defined(__amd64__)
  116         linux_fixup_prot(td, &prot);
  117 #endif
  118 
  119         /* Linux does not check file descriptor when MAP_ANONYMOUS is set. */
  120         fd = (bsd_flags & MAP_ANON) ? -1 : fd;
  121         if (fd != -1) {
  122                 /*
  123                  * Linux follows Solaris mmap(2) description:
  124                  * The file descriptor fildes is opened with
  125                  * read permission, regardless of the
  126                  * protection options specified.
  127                  */
  128 
  129                 error = fget(td, fd, cap_rights_init(&rights, CAP_MMAP), &fp);
  130                 if (error != 0)
  131                         return (error);
  132                 if (fp->f_type != DTYPE_VNODE) {
  133                         fdrop(fp, td);
  134                         return (EINVAL);
  135                 }
  136 
  137                 /* Linux mmap() just fails for O_WRONLY files */
  138                 if (!(fp->f_flag & FREAD)) {
  139                         fdrop(fp, td);
  140                         return (EACCES);
  141                 }
  142 
  143                 fdrop(fp, td);
  144         }
  145 
  146         if (flags & LINUX_MAP_GROWSDOWN) {
  147                 /*
  148                  * The Linux MAP_GROWSDOWN option does not limit auto
  149                  * growth of the region.  Linux mmap with this option
  150                  * takes as addr the initial BOS, and as len, the initial
  151                  * region size.  It can then grow down from addr without
  152                  * limit.  However, Linux threads has an implicit internal
  153                  * limit to stack size of STACK_SIZE.  Its just not
  154                  * enforced explicitly in Linux.  But, here we impose
  155                  * a limit of (STACK_SIZE - GUARD_SIZE) on the stack
  156                  * region, since we can do this with our mmap.
  157                  *
  158                  * Our mmap with MAP_STACK takes addr as the maximum
  159                  * downsize limit on BOS, and as len the max size of
  160                  * the region.  It then maps the top SGROWSIZ bytes,
  161                  * and auto grows the region down, up to the limit
  162                  * in addr.
  163                  *
  164                  * If we don't use the MAP_STACK option, the effect
  165                  * of this code is to allocate a stack region of a
  166                  * fixed size of (STACK_SIZE - GUARD_SIZE).
  167                  */
  168 
  169                 if ((caddr_t)addr + len > vms->vm_maxsaddr) {
  170                         /*
  171                          * Some Linux apps will attempt to mmap
  172                          * thread stacks near the top of their
  173                          * address space.  If their TOS is greater
  174                          * than vm_maxsaddr, vm_map_growstack()
  175                          * will confuse the thread stack with the
  176                          * process stack and deliver a SEGV if they
  177                          * attempt to grow the thread stack past their
  178                          * current stacksize rlimit.  To avoid this,
  179                          * adjust vm_maxsaddr upwards to reflect
  180                          * the current stacksize rlimit rather
  181                          * than the maximum possible stacksize.
  182                          * It would be better to adjust the
  183                          * mmap'ed region, but some apps do not check
  184                          * mmap's return value.
  185                          */
  186                         PROC_LOCK(p);
  187                         vms->vm_maxsaddr = (char *)p->p_sysent->sv_usrstack -
  188                             lim_cur_proc(p, RLIMIT_STACK);
  189                         PROC_UNLOCK(p);
  190                 }
  191 
  192                 /*
  193                  * This gives us our maximum stack size and a new BOS.
  194                  * If we're using VM_STACK, then mmap will just map
  195                  * the top SGROWSIZ bytes, and let the stack grow down
  196                  * to the limit at BOS.  If we're not using VM_STACK
  197                  * we map the full stack, since we don't have a way
  198                  * to autogrow it.
  199                  */
  200                 if (len <= STACK_SIZE - GUARD_SIZE) {
  201                         addr = addr - (STACK_SIZE - GUARD_SIZE - len);
  202                         len = STACK_SIZE - GUARD_SIZE;
  203                 }
  204         }
  205 
  206         /*
  207          * FreeBSD is free to ignore the address hint if MAP_FIXED wasn't
  208          * passed.  However, some Linux applications, like the ART runtime,
  209          * depend on the hint.  If the MAP_FIXED wasn't passed, but the
  210          * address is not zero, try with MAP_FIXED and MAP_EXCL first,
  211          * and fall back to the normal behaviour if that fails.
  212          */
  213         if (addr != 0 && (bsd_flags & MAP_FIXED) == 0 &&
  214             (bsd_flags & MAP_EXCL) == 0) {
  215                 error = kern_mmap(td, addr, len, prot,
  216                     bsd_flags | MAP_FIXED | MAP_EXCL, fd, pos);
  217                 if (error == 0)
  218                         goto out;
  219         }
  220 
  221         error = kern_mmap(td, addr, len, prot, bsd_flags, fd, pos);
  222 out:
  223         LINUX_CTR2(mmap2, "return: %d (%p)", error, td->td_retval[0]);
  224 
  225         return (error);
  226 }
  227 
  228 int
  229 linux_mprotect_common(struct thread *td, uintptr_t addr, size_t len, int prot)
  230 {
  231 
  232 #if defined(__amd64__)
  233         linux_fixup_prot(td, &prot);
  234 #endif
  235         return (kern_mprotect(td, addr, len, prot));
  236 }
  237 
  238 #if defined(__amd64__)
  239 static void
  240 linux_fixup_prot(struct thread *td, int *prot)
  241 {
  242         struct linux_pemuldata *pem;
  243 
  244         if (SV_PROC_FLAG(td->td_proc, SV_ILP32) && *prot & PROT_READ) {
  245                 pem = pem_find(td->td_proc);
  246                 if (pem->persona & LINUX_READ_IMPLIES_EXEC)
  247                         *prot |= PROT_EXEC;
  248         }
  249 
  250 }
  251 #endif

Cache object: cf420e1d2f76d0e82b4efe06e7465fd8


[ 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.