service_runtime/linux/sel_memory.c

   1 /*
   2  * Copyright 2008, Google Inc.
   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 are
   7  * met:
   8  *
   9  *     * Redistributions of source code must retain the above copyright
  10  * notice, this list of conditions and the following disclaimer.
  11  *     * Redistributions in binary form must reproduce the above
  12  * copyright notice, this list of conditions and the following disclaimer
  13  * in the documentation and/or other materials provided with the
  14  * distribution.
  15  *     * Neither the name of Google Inc. nor the names of its
  16  * contributors may be used to endorse or promote products derived from
  17  * this software without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  20  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  21  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  22  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  23  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  24  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  25  * 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
  29  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  30  */
  31
  32 /*
  33  * NaCl Service Runtime memory allocation code
  34  */
  35 #include <stdint.h>
  36 #include <sys/types.h>
  37 #include <sys/stat.h>
  38 #include <fcntl.h>
  39 #include <sys/mman.h>
  40 #include <unistd.h>
  41
  42 #define _XOPEN_SOURCE 600 /* get XSI compliant version of strerror_r */
  43 #include <errno.h>
  44 #include <string.h>
  45
  46 #include "native_client/service_runtime/sel_memory.h"
  47 #include "native_client/service_runtime/nacl_config.h"
  48 #include "native_client/service_runtime/nacl_log.h"
  49 #include "native_client/include/nacl_platform.h"
  50
  51 void NaCl_page_free(void     *p,
  52                     size_t   size)
  53 {
  54   if (p == 0 || size == 0)
  55     return;
  56   (void) munmap(p, size);
  57 }
  58
  59 /*
  60  * Note that NaCl_page_alloc does not allocate pages that satisify
  61  * NaClIsAllocPageMultiple.  On linux/osx, the system does not impose
  62  * any such restrictions, and we only need to enforce the restriction
  63  * on NaCl app code to ensure that the app code is portable across all
  64  * host OSes.
  65  */
  66 int NaCl_page_alloc(void    **p,
  67                     size_t  size)
  68 {
  69   void *addr;
  70
  71   /* Allocating at a fixed, round address aids debugging */
  72   addr = mmap((void *) 0x10000000,
  73               size,
  74               PROT_EXEC | PROT_READ | PROT_WRITE,
  75               MAP_PRIVATE | MAP_ANONYMOUS,
  76               -1,
  77               (off_t) 0);
  78
  79   if (addr == MAP_FAILED) {
  80     addr = NULL;
  81   }
  82
  83   if (NULL != addr) {
  84     *p = addr;
  85   }
  86   return (addr == NULL) ? -ENOMEM : 0;
  87 }
  88
  89 /*
  90 * This is critical to make the text region non-writable, and the data
  91 * region read/write but no exec.  Of course, some kernels do not
  92 * respect the lack of PROT_EXEC.
  93 */
  94 int   NaCl_mprotect(void          *addr,
  95                     size_t        len,
  96                     int           prot)
  97 {
  98   int  ret;
  99
 100   return (ret = mprotect(addr, len, prot)) == -1 ? -errno : ret;
 101 }
 102
 103 int   NaCl_madvise(void           *start,
 104                    size_t         length,
 105                    int            advice)
 106 {
 107   int ret;
 108
 109   /*
 110    * MADV_DONTNEED and MADV_NORMAL are needed
 111    */
 112   return (ret = madvise(start, length, advice)) == -1 ? -errno : ret;
 113 }