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  * Copyright (c) 2011, 2012 OpenSSL Software Foundation, Inc.
   7  *
   8  * This file is part of linux cryptodev.
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License
  12  * as published by the Free Software Foundation; either version 2
  13  * of the License, or (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  23  * 02110-1301, USA.
  24  */
  25
  26 #include <crypto/hash.h>
  27 #include <linux/crypto.h>
  28 #include <linux/mm.h>
  29 #include <linux/highmem.h>
  30 #include <linux/ioctl.h>
  31 #include <linux/random.h>
  32 #include <linux/syscalls.h>
  33 #include <linux/pagemap.h>
  34 #include <linux/uaccess.h>
  35 #include <crypto/scatterwalk.h>
  36 #include <linux/scatterlist.h>
  37 #include "cryptodev_int.h"
  38 #include "zc.h"
  39 #include "version.h"
  40
  41 /* Helper functions to assist zero copy.
  42  * This needs to be redesigned and moved out of the session. --nmav
  43  */
  44
  45 /* offset of buf in it's first page */
  46 #define PAGEOFFSET(buf) ((unsigned long)buf & ~PAGE_MASK)
  47
  48 /* fetch the pages addr resides in into pg and initialise sg with them */
  49 int __get_userbuf(uint8_t __user *addr, uint32_t len, int write,
  50                 int pgcount, struct page **pg, struct scatterlist *sg,
  51                 struct task_struct *task, struct mm_struct *mm)
  52 {
  53         int ret, pglen, i = 0;
  54         struct scatterlist *sgp;
  55
  56         down_write(&mm->mmap_sem);
  57         ret = get_user_pages(task, mm,
  58                         (unsigned long)addr, pgcount, write, 0, pg, NULL);
  59         up_write(&mm->mmap_sem);
  60         if (ret != pgcount)
  61                 return -EINVAL;
  62
  63         sg_init_table(sg, pgcount);
  64
  65         pglen = min((ptrdiff_t)(PAGE_SIZE - PAGEOFFSET(addr)), (ptrdiff_t)len);
  66         sg_set_page(sg, pg[i++], pglen, PAGEOFFSET(addr));
  67
  68         len -= pglen;
  69         for (sgp = sg_next(sg); len; sgp = sg_next(sgp)) {
  70                 pglen = min((uint32_t)PAGE_SIZE, len);
  71                 sg_set_page(sgp, pg[i++], pglen, 0);
  72                 len -= pglen;
  73         }
  74         sg_mark_end(sg_last(sg, pgcount));
  75         return 0;
  76 }
  77
  78 int adjust_sg_array(struct csession * ses, int pagecount)
  79 {
  80 struct scatterlist *sg;
  81 struct page **pages;
  82 int array_size;
  83
  84         for (array_size = ses->array_size; array_size < pagecount;
  85              array_size *= 2)
  86                 ;
  87
  88         dprintk(2, KERN_DEBUG, "%s: reallocating to %d elements\n",
  89                         __func__, array_size);
  90         pages = krealloc(ses->pages, array_size * sizeof(struct page *),
  91                          GFP_KERNEL);
  92         if (unlikely(!pages))
  93                 return -ENOMEM;
  94         ses->pages = pages;
  95         sg = krealloc(ses->sg, array_size * sizeof(struct scatterlist),
  96                       GFP_KERNEL);
  97         if (unlikely(!sg))
  98                 return -ENOMEM;
  99         ses->sg = sg;
 100         ses->array_size = array_size;
 101
 102         return 0;
 103 }
 104
 105 void release_user_pages(struct csession *ses)
 106 {
 107 unsigned int i;
 108
 109         for (i=0;i<ses->used_pages;i++) {
 110                 if (!PageReserved(ses->pages[i]))
 111                         SetPageDirty(ses->pages[i]);
 112
 113                 if (ses->readable_pages == 0)
 114                         flush_dcache_page(ses->pages[i]);
 115                 else
 116                         ses->readable_pages--;
 117
 118                 page_cache_release(ses->pages[i]);
 119         }
 120         ses->used_pages = 0;
 121 }
 122
 123 /* make src and dst available in scatterlists.
 124  * dst might be the same as src.
 125  */
 126 int get_userbuf(struct csession *ses, void* __user src, int src_len,
 127                 void* __user dst, int dst_len,
 128                 struct task_struct *task, struct mm_struct *mm,
 129                 struct scatterlist **src_sg,
 130                 struct scatterlist **dst_sg)
 131 {
 132         int src_pagecount, dst_pagecount = 0, pagecount, write_src = 1;
 133         int rc;
 134
 135         if (src == NULL)
 136                 return -EINVAL;
 137
 138         if (ses->alignmask && !IS_ALIGNED((unsigned long)src, ses->alignmask)) {
 139                 dprintk(2, KERN_WARNING, "%s: careful - source address %lx is not %d byte aligned\n",
 140                                 __func__, (unsigned long)src, ses->alignmask + 1);
 141         }
 142
 143         if (src == dst) {
 144                 /* dst == src */
 145                 src_len = max(src_len, dst_len);
 146                 dst_len = src_len;
 147         }
 148
 149         src_pagecount = PAGECOUNT(src, src_len);
 150         if (!ses->cdata.init) {         /* hashing only */
 151                 write_src = 0;
 152         } else if (src != dst) {        /* non-in-situ transformation */
 153                 if (dst == NULL)
 154                         return -EINVAL;
 155
 156                 dst_pagecount = PAGECOUNT(dst, dst_len);
 157                 write_src = 0;
 158
 159                 if (ses->alignmask && !IS_ALIGNED((unsigned long)dst, ses->alignmask)) {
 160                         dprintk(2, KERN_WARNING, "%s: careful - destination address %lx is not %d byte aligned\n",
 161                                         __func__, (unsigned long)dst, ses->alignmask + 1);
 162                 }
 163         }
 164         ses->used_pages = pagecount = src_pagecount + dst_pagecount;
 165
 166         if (write_src) ses->readable_pages = 0;
 167         else ses->readable_pages = src_pagecount;
 168
 169         if (pagecount > ses->array_size) {
 170                 rc = adjust_sg_array(ses, pagecount);
 171                 if (rc)
 172                         return rc;
 173         }
 174
 175         rc = __get_userbuf(src, src_len, write_src, src_pagecount,
 176                            ses->pages, ses->sg, task, mm);
 177         if (unlikely(rc)) {
 178                 dprintk(1, KERN_ERR,
 179                         "failed to get user pages for data input\n");
 180                 return -EINVAL;
 181         }
 182         (*src_sg) = (*dst_sg) = ses->sg;
 183
 184         if (!dst_pagecount)
 185                 return 0;
 186
 187         (*dst_sg) = ses->sg + src_pagecount;
 188
 189         rc = __get_userbuf(dst, dst_len, 1, dst_pagecount,
 190                            ses->pages + src_pagecount, *dst_sg,
 191                            task, mm);
 192         if (unlikely(rc)) {
 193                 dprintk(1, KERN_ERR,
 194                         "failed to get user pages for data output\n");
 195                 release_user_pages(ses);
 196                 return -EINVAL;
 197         }
 198         return 0;
 199 }