sos-code-article7/sos/uaccess.c

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2017-01-29 14:33:48 +01:00
/* Copyright (C) 2005 David Decotigny
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
USA.
*/
#include <hwcore/paging.h>
#include <sos/thread.h>
#include <sos/assert.h>
#include <sos/kmalloc.h>
#include "uaccess.h"
/**
* Helper function to force the MMU to switch to the address space of
* the process
*/
static sos_ret_t bindto_user_mm_context()
{
struct sos_thread * current_thread;
struct sos_mm_context * process_mm_ctxt;
current_thread = sos_thread_get_current();
SOS_ASSERT_FATAL(NULL != current_thread->process);
/* Switch to the user's address space */
process_mm_ctxt
= sos_process_get_mm_context(current_thread->process);
return sos_thread_change_current_mm_context(process_mm_ctxt);
}
/**
* Helper macro to restore the MMU configuration prior to
* bindto_user_mm_context()
*/
#define unbindto_user_mm_context() \
sos_thread_change_current_mm_context(NULL)
static sos_ret_t nocheck_user_memcpy(sos_vaddr_t dest,
sos_vaddr_t src,
sos_size_t size,
sos_bool_t transfer_from_user)
{
sos_ret_t retval;
retval = bindto_user_mm_context();
if (SOS_OK != retval)
return retval;
memcpy((void*) dest, (void*) src, size);
retval = unbindto_user_mm_context();
if (SOS_OK != retval)
return retval;
return size;
}
sos_ret_t sos_memcpy_from_user(sos_vaddr_t kernel_to,
sos_uaddr_t user_from,
sos_size_t size)
{
/* Make sure user is trying to access user space */
if (user_from < SOS_PAGING_BASE_USER_ADDRESS)
return -SOS_EPERM;
if (user_from > SOS_PAGING_TOP_USER_ADDRESS - size)
return -SOS_EPERM;
return nocheck_user_memcpy(kernel_to, user_from, size, TRUE);
}
sos_ret_t sos_memcpy_to_user(sos_uaddr_t user_to,
sos_vaddr_t kernel_from,
sos_size_t size)
{
/* Make sure user is trying to access user space */
if (user_to < SOS_PAGING_BASE_USER_ADDRESS)
return -SOS_EPERM;
if (user_to > SOS_PAGING_TOP_USER_ADDRESS - size)
return -SOS_EPERM;
return nocheck_user_memcpy(user_to, kernel_from, size, FALSE);
}
sos_ret_t sos_strnlen_from_user(sos_uaddr_t user_str, sos_size_t max_len)
{
sos_ret_t retval, len;
/* Make sure user is trying to access user space */
if (user_str < SOS_PAGING_BASE_USER_ADDRESS)
return -SOS_EPERM;
/* Don't allow invalid max_len */
if ( (max_len < 1) || (max_len > SOS_PAGING_USER_SPACE_SIZE) )
return -SOS_EINVAL;
retval = bindto_user_mm_context();
if (SOS_OK != retval)
return retval;
len = strnlen((const char*)user_str, max_len);
retval = unbindto_user_mm_context();
if (SOS_OK != retval)
return retval;
return len;
}
static sos_ret_t nocheck_user_strzcpy(char *dst, const char *src,
sos_size_t len)
{
sos_ret_t retval;
retval = bindto_user_mm_context();
if (SOS_OK != retval)
return retval;
strzcpy(dst, src, len);
retval = unbindto_user_mm_context();
if (SOS_OK != retval)
return retval;
return SOS_OK;
}
sos_ret_t sos_strzcpy_from_user(char *kernel_to, sos_uaddr_t user_from,
sos_size_t max_len)
{
/* Make sure user is trying to access user space */
if ((sos_uaddr_t)user_from < SOS_PAGING_BASE_USER_ADDRESS)
return -SOS_EPERM;
/* Don't allow invalid max_len */
if ( (max_len < 1) || (max_len > SOS_PAGING_USER_SPACE_SIZE) )
return -SOS_EINVAL;
return nocheck_user_strzcpy(kernel_to, (const char*)user_from, max_len);
}
sos_ret_t sos_strzcpy_to_user(sos_uaddr_t user_to, const char *kernel_from,
sos_size_t max_len)
{
/* Make sure user is trying to access user space */
if ((sos_uaddr_t)user_to < SOS_PAGING_BASE_USER_ADDRESS)
return -SOS_EPERM;
/* Don't allow invalid max_len */
if ( (max_len < 1) || (max_len > SOS_PAGING_USER_SPACE_SIZE) )
return -SOS_EINVAL;
return nocheck_user_strzcpy((char*)user_to, kernel_from, max_len);
}
sos_ret_t sos_strndup_from_user(char ** kernel_to, sos_uaddr_t from_user,
sos_size_t max_len,
sos_ui32_t kmalloc_flags)
{
sos_ret_t retval = sos_strnlen_from_user(from_user, max_len);
if (retval < 0)
return retval;
*kernel_to = (char*)sos_kmalloc(retval + 1, kmalloc_flags);
if (NULL == *kernel_to)
return -SOS_ENOMEM;
retval = sos_strzcpy_from_user(*kernel_to, from_user, retval + 1);
if (SOS_OK != retval)
{
sos_kfree((sos_vaddr_t)*kernel_to);
*kernel_to = NULL;
}
return retval;
}