zc.c

   1 /*
   2  * Driver for /dev/crypto device (aka CryptoDev)
   3  *
   4  * Copyright (c) 2009-2011 Nikos Mavrogiannopoulos <nmav@gnutls.org>
   5  * Copyright (c) 2010 Phil Sutter
   6  *
   7  * This file is part of linux cryptodev.
   8  *
   9  * This program is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU General Public License
  11  * as published by the Free Software Foundation; either version 2
  12  * of the License, or (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with this program; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  22  * 02110-1301, USA.
  23  */
  24
  25 #include <crypto/hash.h>
  26 #include <linux/crypto.h>
  27 #include <linux/mm.h>
  28 #include <linux/highmem.h>
  29 #include <linux/ioctl.h>
  30 #include <linux/random.h>
  31 #include <linux/syscalls.h>
  32 #include <linux/pagemap.h>
  33 #include <linux/uaccess.h>
  34 #include <crypto/scatterwalk.h>
  35 #include <linux/scatterlist.h>
  36 #include "cryptodev_int.h"
  37 #include "version.h"
  38
  39 /* Helper functions to assist zero copy.
  40  * This needs to be redesigned and moved out of the session. --nmav
  41  */
  42
  43 /* offset of buf in it's first page */
  44 #define PAGEOFFSET(buf) ((unsigned long)buf & ~PAGE_MASK)
  45
  46 /* fetch the pages addr resides in into pg and initialise sg with them */
  47 int __get_userbuf(uint8_t __user *addr, uint32_t len, int write,
  48                 int pgcount, struct page **pg, struct scatterlist *sg,
  49                 struct task_struct *task, struct mm_struct *mm)
  50 {
  51         int ret, pglen, i = 0;
  52         struct scatterlist *sgp;
  53
  54         down_write(&mm->mmap_sem);
  55         ret = get_user_pages(task, mm,
  56                         (unsigned long)addr, pgcount, write, 0, pg, NULL);
  57         up_write(&mm->mmap_sem);
  58         if (ret != pgcount)
  59                 return -EINVAL;
  60
  61         sg_init_table(sg, pgcount);
  62
  63         pglen = min((ptrdiff_t)(PAGE_SIZE - PAGEOFFSET(addr)), (ptrdiff_t)len);
  64         sg_set_page(sg, pg[i++], pglen, PAGEOFFSET(addr));
  65
  66         len -= pglen;
  67         for (sgp = sg_next(sg); len; sgp = sg_next(sgp)) {
  68                 pglen = min((uint32_t)PAGE_SIZE, len);
  69                 sg_set_page(sgp, pg[i++], pglen, 0);
  70                 len -= pglen;
  71         }
  72         sg_mark_end(sg_last(sg, pgcount));
  73         return 0;
  74 }
  75
  76 int adjust_sg_array(struct csession * ses, int pagecount)
  77 {
  78 struct scatterlist *sg;
  79 struct page **pages;
  80 int array_size;
  81
  82         for (array_size = ses->array_size; array_size < pagecount;
  83              array_size *= 2)
  84                 ;
  85
  86         dprintk(2, KERN_DEBUG, "%s: reallocating to %d elements\n",
  87                         __func__, array_size);
  88         pages = krealloc(ses->pages, array_size * sizeof(struct page *),
  89                          GFP_KERNEL);
  90         if (unlikely(!pages))
  91                 return -ENOMEM;
  92         ses->pages = pages;
  93         sg = krealloc(ses->sg, array_size * sizeof(struct scatterlist),
  94                       GFP_KERNEL);
  95         if (unlikely(!sg))
  96                 return -ENOMEM;
  97         ses->sg = sg;
  98         ses->array_size = array_size;
  99
 100         return 0;
 101 }
 102
 103 void release_user_pages(struct page **pg, int pagecount)
 104 {
 105         while (pagecount--) {
 106                 if (!PageReserved(pg[pagecount]))
 107                         SetPageDirty(pg[pagecount]);
 108                 page_cache_release(pg[pagecount]);
 109         }
 110 }