path: root/utils.c

/*
 * New driver for /dev/crypto device (aka CryptoDev)
 *
 * Copyright (c) 2010 Red Hat Inc.
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
 * USA.
 *
 * Red Hat Author: Miloslav Trmač
 *
 */

#include <linux/slab.h>
#include <linux/uaccess.h>
#include <net/netlink.h>
#include "ncr-int.h"
#include "utils.h"

static const struct nla_policy ncr_attr_policy[NCR_ATTR_MAX + 1] = {
	[NCR_ATTR_ALGORITHM] = { NLA_U32, 0 },
	[NCR_ATTR_DERIVATION_ALGORITHM] = { NLA_U32, 0 },
	[NCR_ATTR_KEY_FLAGS] = { NLA_U32, 0 },
	[NCR_ATTR_KEY_TYPE] = { NLA_U32, 0 },
	[NCR_ATTR_SECRET_KEY_BITS] = { NLA_U32, 0 },
	[NCR_ATTR_RSA_MODULUS_BITS] = { NLA_U32, 0 },
	[NCR_ATTR_RSA_E] = { NLA_BINARY, 0 },
	[NCR_ATTR_DSA_P_BITS] = { NLA_U32, 0 },
	[NCR_ATTR_DSA_Q_BITS] = { NLA_U32, 0 },
	[NCR_ATTR_DH_PRIME] = { NLA_BINARY, 0 },
	[NCR_ATTR_DH_BASE] = { NLA_BINARY, 0 },
	[NCR_ATTR_DH_PUBLIC] = { NLA_BINARY, 0 },
	[NCR_ATTR_WANTED_ATTRS] = { NLA_BINARY, 0 },
};

void *__ncr_get_input_args(void *fixed, struct nlattr *tb[], size_t fixed_size,
			   u32 *input_size_ptr, const void __user *arg)
{
	size_t input_size, buf_size;
	void *buf;
	int ret;

	if (unlikely(copy_from_user(fixed, arg, fixed_size))) {
		err();
		return ERR_PTR(-EFAULT);
	}
	input_size = *input_size_ptr;

	/* NCR_GET_INPUT_ARGS/NCR_GET_INPUT_ARGS_NO_OUTPUT has verified
	   fixed_size is correctly aligned for a struct nlattr. */
	if (input_size == 0)
		input_size = fixed_size;
	else if (unlikely(input_size < fixed_size)) {
		err();
		return ERR_PTR(-EINVAL);
	}
	buf_size = input_size - fixed_size;
	if (unlikely(buf_size > NCR_MAX_ATTR_SIZE)) {
		err();
		return ERR_PTR(-EOVERFLOW);
	}

	if (buf_size == 0)
		buf = NULL;
	else {
		const char __user *var_arg;

		buf = kmalloc(buf_size, GFP_KERNEL);
		if (unlikely(buf == NULL)) {
			err();
			return ERR_PTR(-ENOMEM);
		}
		var_arg = (const char __user *)arg + fixed_size;
		if (unlikely(copy_from_user(buf, var_arg, buf_size))) {
			err();
			ret = -EFAULT;
			goto err_buf;
		}
	}

	ret = nla_parse(tb, NCR_ATTR_MAX, buf, buf_size, ncr_attr_policy);
	if (ret != 0) {
		err();
		goto err_buf;
	}

	return buf;

err_buf:
	kfree(buf);
	return ERR_PTR(ret);
}

static int update_output_size(void __user *arg, size_t output_size_offset,
			      u32 old_value, u32 new_value)
{
	if (old_value != 0 && old_value != new_value) {
		u32 __user *dest;

		dest = (u32 __user *)((char __user *)arg + output_size_offset);
		return put_user(new_value, dest);
	}
	return 0;
}

void *__ncr_get_input_args_no_output(void *fixed, struct nlattr *tb[],
				     size_t fixed_size, u32 *input_size_ptr,
				     size_t output_size_offset,
				     void __user *arg)
{
	void *attr_buf;
	u32 output_size;
	int ret;

	attr_buf = __ncr_get_input_args(fixed, tb, fixed_size, input_size_ptr,
					arg);
	if (IS_ERR(attr_buf))
		return attr_buf;

	output_size = *(const u32 *)((const char *)fixed + output_size_offset);
	ret = update_output_size(arg, output_size_offset, output_size,
				 fixed_size);
	if (ret != 0) {
		kfree(attr_buf);
		return ERR_PTR(ret);
	}
	return attr_buf;
}

int __ncr_out_init(struct ncr_out *out, const void *fixed, size_t fixed_size,
		   size_t output_size_offset, void __user *arg)
{
	u32 output_size;

	/* NCR_OUT_INIT has verified fixed_size is correctly aligned for a
	   struct nlattr. */
	output_size = *(const u32 *)((const char *)fixed + output_size_offset);
	if (output_size == 0)
		out->left = 0;
	else {
		/* NCR_OUT_INIT has verified fixed_size is correctly aligned for
		   a struct nlattr. */
		if (output_size < fixed_size)
			return -EINVAL;
		out->left = min_t(size_t, output_size - fixed_size,
				  NCR_MAX_ATTR_SIZE);
	}
	out->buf = kmalloc(out->left, GFP_KERNEL);
	if (out->buf == NULL)
		return -ENOMEM;
	out->p = out->buf;
	out->arg = arg;
	out->output_size_offset = output_size_offset;
	out->fixed_size = fixed_size;
	out->orig_output_size = output_size;
	return 0;
}

int ncr_out_finish(struct ncr_out *out)
{
	size_t buf_size;

	buf_size = (char *)out->p - (char *)out->buf;
	if (buf_size != 0) {
		if (unlikely(copy_to_user((char __user *)out->arg
					  + out->fixed_size,
					  out->buf, buf_size)))
			return -EFAULT;
	}

	return update_output_size(out->arg, out->output_size_offset,
				  out->orig_output_size,
				  out->fixed_size + buf_size);
}

void ncr_out_free(struct ncr_out *out)
{
	kfree(out->buf);
}

struct nlattr *ncr_out_reserve(struct ncr_out *out, int attrtype, int attrlen)
{
	size_t needed;
	struct nlattr *nla;

	needed = nla_total_size(attrlen);
	if (out->left < needed)
		ERR_PTR(-ERANGE);
	nla = out->p;
	out->p = (char *)out->p + needed;
	out->left -= needed;

	nla->nla_len = nla_attr_size(attrlen);
	nla->nla_type = attrtype;
	memset((unsigned char *)nla + nla->nla_len, 0, nla_padlen(attrlen));
	return nla;
}

int ncr_out_put(struct ncr_out *out, int attrtype, int attrlen, const void *data)
{
	struct nlattr *nla;

	nla = ncr_out_reserve(out, attrtype, attrlen);
	if (IS_ERR(nla))
		return PTR_ERR(nla);
	memcpy(nla_data(nla), data, attrlen);
	return 0;
}

/**
 * Initialize a nlattr with @attrtype as a buffer of maximum possible size in
 * @out.  The buffer must be finalized using ncr_out_commit_buffer.
 */
struct nlattr *ncr_out_begin_buffer(struct ncr_out *out, int attrtype)
{
	struct nlattr *nla;

	if (out->left < NLA_HDRLEN)
		return ERR_PTR(-ERANGE);
	nla = out->p;

	/* Ensure the rounding down of out->left does not decrease it below
	   NLA_HDRLEN. */
	BUILD_BUG_ON(NLA_ALIGN(NLA_HDRLEN) != NLA_HDRLEN);
	nla->nla_len = out->left & ~(NLA_ALIGNTO - 1);
	nla->nla_type = attrtype;
	return nla;
}

/**
 * Set the length of buffer initialied in @out with ncr_out_begin_buffer() to
 * @attrlen and allow adding more attributes.
 */
void ncr_out_commit_buffer(struct ncr_out *out, int attrlen)
{
	struct nlattr *nla;
	size_t total;

	nla = out->p;
	nla->nla_len = nla_attr_size(attrlen);
	memset((unsigned char *)nla + nla->nla_len, 0, nla_padlen(attrlen));
	total = nla_total_size(attrlen);

	out->p = (char *)out->p + total;
	out->left -= total;
}