alistair23-linux/net/netfilter/nft_immediate.c
Pablo Neira Ayuso 591054469b netfilter: nf_tables: revisit chain/object refcounting from elements
Andreas reports that the following incremental update using our commit
protocol doesn't work.

 # nft -f incremental-update.nft
 delete element ip filter client_to_any { 10.180.86.22 : goto CIn_1 }
 delete chain ip filter CIn_1
 ... Error: Could not process rule: Device or resource busy

The existing code is not well-integrated into the commit phase protocol,
since element deletions do not result in refcount decrement from the
preparation phase. This results in bogus EBUSY errors like the one
above.

Two new functions come with this patch:

* nft_set_elem_activate() function is used from the abort path, to
  restore the set element refcounting on objects that occurred from
  the preparation phase.

* nft_set_elem_deactivate() that is called from nft_del_setelem() to
  decrement set element refcounting on objects from the preparation
  phase in the commit protocol.

The nft_data_uninit() has been renamed to nft_data_release() since this
function does not uninitialize any data store in the data register,
instead just releases the references to objects. Moreover, a new
function nft_data_hold() has been introduced to be used from
nft_set_elem_activate().

Reported-by: Andreas Schultz <aschultz@tpip.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2017-05-15 12:51:41 +02:00

123 lines
3.2 KiB
C

/*
* Copyright (c) 2008-2009 Patrick McHardy <kaber@trash.net>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* Development of this code funded by Astaro AG (http://www.astaro.com/)
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/netlink.h>
#include <linux/netfilter.h>
#include <linux/netfilter/nf_tables.h>
#include <net/netfilter/nf_tables_core.h>
#include <net/netfilter/nf_tables.h>
struct nft_immediate_expr {
struct nft_data data;
enum nft_registers dreg:8;
u8 dlen;
};
static void nft_immediate_eval(const struct nft_expr *expr,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
{
const struct nft_immediate_expr *priv = nft_expr_priv(expr);
nft_data_copy(&regs->data[priv->dreg], &priv->data, priv->dlen);
}
static const struct nla_policy nft_immediate_policy[NFTA_IMMEDIATE_MAX + 1] = {
[NFTA_IMMEDIATE_DREG] = { .type = NLA_U32 },
[NFTA_IMMEDIATE_DATA] = { .type = NLA_NESTED },
};
static int nft_immediate_init(const struct nft_ctx *ctx,
const struct nft_expr *expr,
const struct nlattr * const tb[])
{
struct nft_immediate_expr *priv = nft_expr_priv(expr);
struct nft_data_desc desc;
int err;
if (tb[NFTA_IMMEDIATE_DREG] == NULL ||
tb[NFTA_IMMEDIATE_DATA] == NULL)
return -EINVAL;
err = nft_data_init(ctx, &priv->data, sizeof(priv->data), &desc,
tb[NFTA_IMMEDIATE_DATA]);
if (err < 0)
return err;
priv->dlen = desc.len;
priv->dreg = nft_parse_register(tb[NFTA_IMMEDIATE_DREG]);
err = nft_validate_register_store(ctx, priv->dreg, &priv->data,
desc.type, desc.len);
if (err < 0)
goto err1;
return 0;
err1:
nft_data_release(&priv->data, desc.type);
return err;
}
static void nft_immediate_destroy(const struct nft_ctx *ctx,
const struct nft_expr *expr)
{
const struct nft_immediate_expr *priv = nft_expr_priv(expr);
return nft_data_release(&priv->data, nft_dreg_to_type(priv->dreg));
}
static int nft_immediate_dump(struct sk_buff *skb, const struct nft_expr *expr)
{
const struct nft_immediate_expr *priv = nft_expr_priv(expr);
if (nft_dump_register(skb, NFTA_IMMEDIATE_DREG, priv->dreg))
goto nla_put_failure;
return nft_data_dump(skb, NFTA_IMMEDIATE_DATA, &priv->data,
nft_dreg_to_type(priv->dreg), priv->dlen);
nla_put_failure:
return -1;
}
static int nft_immediate_validate(const struct nft_ctx *ctx,
const struct nft_expr *expr,
const struct nft_data **data)
{
const struct nft_immediate_expr *priv = nft_expr_priv(expr);
if (priv->dreg == NFT_REG_VERDICT)
*data = &priv->data;
return 0;
}
static const struct nft_expr_ops nft_imm_ops = {
.type = &nft_imm_type,
.size = NFT_EXPR_SIZE(sizeof(struct nft_immediate_expr)),
.eval = nft_immediate_eval,
.init = nft_immediate_init,
.destroy = nft_immediate_destroy,
.dump = nft_immediate_dump,
.validate = nft_immediate_validate,
};
struct nft_expr_type nft_imm_type __read_mostly = {
.name = "immediate",
.ops = &nft_imm_ops,
.policy = nft_immediate_policy,
.maxattr = NFTA_IMMEDIATE_MAX,
.owner = THIS_MODULE,
};