linux_mmap.c

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    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/12.0/sys/compat/linux/linux_mmap.c 333425 2018-05-09 18:47:24Z mmacy $
   32  */
   33 
   34 #include <sys/cdefs.h>
   35 __FBSDID("$FreeBSD: releng/12.0/sys/compat/linux/linux_mmap.c 333425 2018-05-09 18:47:24Z mmacy $");
   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         LINUX_CTR6(mmap2, "0x%lx, %ld, %ld, 0x%08lx, %ld, 0x%lx",
   76             addr, len, prot, flags, fd, pos);
   77 
   78         error = 0;
   79         bsd_flags = 0;
   80         fp = NULL;
   81 
   82         /*
   83          * Linux mmap(2):
   84          * You must specify exactly one of MAP_SHARED and MAP_PRIVATE
   85          */
   86         if (!((flags & LINUX_MAP_SHARED) ^ (flags & LINUX_MAP_PRIVATE)))
   87                 return (EINVAL);
   88 
   89         if (flags & LINUX_MAP_SHARED)
   90                 bsd_flags |= MAP_SHARED;
   91         if (flags & LINUX_MAP_PRIVATE)
   92                 bsd_flags |= MAP_PRIVATE;
   93         if (flags & LINUX_MAP_FIXED)
   94                 bsd_flags |= MAP_FIXED;
   95         if (flags & LINUX_MAP_ANON) {
   96                 /* Enforce pos to be on page boundary, then ignore. */
   97                 if ((pos & PAGE_MASK) != 0)
   98                         return (EINVAL);
   99                 pos = 0;
  100                 bsd_flags |= MAP_ANON;
  101         } else
  102                 bsd_flags |= MAP_NOSYNC;
  103         if (flags & LINUX_MAP_GROWSDOWN)
  104                 bsd_flags |= MAP_STACK;
  105 
  106         /*
  107          * PROT_READ, PROT_WRITE, or PROT_EXEC implies PROT_READ and PROT_EXEC
  108          * on Linux/i386 if the binary requires executable stack.
  109          * We do this only for IA32 emulation as on native i386 this is does not
  110          * make sense without PAE.
  111          *
  112          * XXX. Linux checks that the file system is not mounted with noexec.
  113          */
  114 #if defined(__amd64__)
  115         linux_fixup_prot(td, &prot);
  116 #endif
  117 
  118         /* Linux does not check file descriptor when MAP_ANONYMOUS is set. */
  119         fd = (bsd_flags & MAP_ANON) ? -1 : fd;
  120         if (fd != -1) {
  121                 /*
  122                  * Linux follows Solaris mmap(2) description:
  123                  * The file descriptor fildes is opened with
  124                  * read permission, regardless of the
  125                  * protection options specified.
  126                  */
  127 
  128                 error = fget(td, fd, &cap_mmap_rights, &fp);
  129                 if (error != 0)
  130                         return (error);
  131                 if (fp->f_type != DTYPE_VNODE && fp->f_type != DTYPE_DEV) {
  132                         fdrop(fp, td);
  133                         return (EINVAL);
  134                 }
  135 
  136                 /* Linux mmap() just fails for O_WRONLY files */
  137                 if (!(fp->f_flag & FREAD)) {
  138                         fdrop(fp, td);
  139                         return (EACCES);
  140                 }
  141 
  142                 fdrop(fp, td);
  143         }
  144 
  145         if (flags & LINUX_MAP_GROWSDOWN) {
  146                 /*
  147                  * The Linux MAP_GROWSDOWN option does not limit auto
  148                  * growth of the region.  Linux mmap with this option
  149                  * takes as addr the initial BOS, and as len, the initial
  150                  * region size.  It can then grow down from addr without
  151                  * limit.  However, Linux threads has an implicit internal
  152                  * limit to stack size of STACK_SIZE.  Its just not
  153                  * enforced explicitly in Linux.  But, here we impose
  154                  * a limit of (STACK_SIZE - GUARD_SIZE) on the stack
  155                  * region, since we can do this with our mmap.
  156                  *
  157                  * Our mmap with MAP_STACK takes addr as the maximum
  158                  * downsize limit on BOS, and as len the max size of
  159                  * the region.  It then maps the top SGROWSIZ bytes,
  160                  * and auto grows the region down, up to the limit
  161                  * in addr.
  162                  *
  163                  * If we don't use the MAP_STACK option, the effect
  164                  * of this code is to allocate a stack region of a
  165                  * fixed size of (STACK_SIZE - GUARD_SIZE).
  166                  */
  167 
  168                 if ((caddr_t)addr + len > vms->vm_maxsaddr) {
  169                         /*
  170                          * Some Linux apps will attempt to mmap
  171                          * thread stacks near the top of their
  172                          * address space.  If their TOS is greater
  173                          * than vm_maxsaddr, vm_map_growstack()
  174                          * will confuse the thread stack with the
  175                          * process stack and deliver a SEGV if they
  176                          * attempt to grow the thread stack past their
  177                          * current stacksize rlimit.  To avoid this,
  178                          * adjust vm_maxsaddr upwards to reflect
  179                          * the current stacksize rlimit rather
  180                          * than the maximum possible stacksize.
  181                          * It would be better to adjust the
  182                          * mmap'ed region, but some apps do not check
  183                          * mmap's return value.
  184                          */
  185                         PROC_LOCK(p);
  186                         vms->vm_maxsaddr = (char *)p->p_sysent->sv_usrstack -
  187                             lim_cur_proc(p, RLIMIT_STACK);
  188                         PROC_UNLOCK(p);
  189                 }
  190 
  191                 /*
  192                  * This gives us our maximum stack size and a new BOS.
  193                  * If we're using VM_STACK, then mmap will just map
  194                  * the top SGROWSIZ bytes, and let the stack grow down
  195                  * to the limit at BOS.  If we're not using VM_STACK
  196                  * we map the full stack, since we don't have a way
  197                  * to autogrow it.
  198                  */
  199                 if (len <= STACK_SIZE - GUARD_SIZE) {
  200                         addr = addr - (STACK_SIZE - GUARD_SIZE - len);
  201                         len = STACK_SIZE - GUARD_SIZE;
  202                 }
  203         }
  204 
  205         /*
  206          * FreeBSD is free to ignore the address hint if MAP_FIXED wasn't
  207          * passed.  However, some Linux applications, like the ART runtime,
  208          * depend on the hint.  If the MAP_FIXED wasn't passed, but the
  209          * address is not zero, try with MAP_FIXED and MAP_EXCL first,
  210          * and fall back to the normal behaviour if that fails.
  211          */
  212         if (addr != 0 && (bsd_flags & MAP_FIXED) == 0 &&
  213             (bsd_flags & MAP_EXCL) == 0) {
  214                 error = kern_mmap(td, addr, len, prot,
  215                     bsd_flags | MAP_FIXED | MAP_EXCL, fd, pos);
  216                 if (error == 0)
  217                         goto out;
  218         }
  219 
  220         error = kern_mmap(td, addr, len, prot, bsd_flags, fd, pos);
  221 out:
  222         LINUX_CTR2(mmap2, "return: %d (%p)", error, td->td_retval[0]);
  223 
  224         return (error);
  225 }
  226 
  227 int
  228 linux_mprotect_common(struct thread *td, uintptr_t addr, size_t len, int prot)
  229 {
  230 
  231 #if defined(__amd64__)
  232         linux_fixup_prot(td, &prot);
  233 #endif
  234         return (kern_mprotect(td, addr, len, prot));
  235 }
  236 
  237 #if defined(__amd64__)
  238 static void
  239 linux_fixup_prot(struct thread *td, int *prot)
  240 {
  241         struct linux_pemuldata *pem;
  242 
  243         if (SV_PROC_FLAG(td->td_proc, SV_ILP32) && *prot & PROT_READ) {
  244                 pem = pem_find(td->td_proc);
  245                 if (pem->persona & LINUX_READ_IMPLIES_EXEC)
  246                         *prot |= PROT_EXEC;
  247         }
  248 
  249 }
  250 #endif
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FreeBSD/Linux Kernel Cross Reference sys/compat/linux/linux_mmap.c

FreeBSD/Linux Kernel Cross Reference
sys/compat/linux/linux_mmap.c
