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alistair23-linux/net/netfilter/nft_payload.c
Liping Zhang a20877b5ed netfilter: nf_tables: check tprot_set first when we use xt.thoff 
pkt->xt.thoff is not always set properly, but we use it without any check.
For payload expr, it will cause wrong results. For nftrace, we may notify
the wrong network or transport header to the user space, furthermore,
input the following nft rules, warning message will be printed out:
  # nft add rule arp filter output meta nftrace set 1

  WARNING: CPU: 0 PID: 13428 at net/netfilter/nf_tables_trace.c:263
  nft_trace_notify+0x4a3/0x5e0 [nf_tables]
  Call Trace:
  [<ffffffff813d58ae>] dump_stack+0x63/0x85
  [<ffffffff810a4c0b>] __warn+0xcb/0xf0
  [<ffffffff810a4d3d>] warn_slowpath_null+0x1d/0x20
  [<ffffffffa0589703>] nft_trace_notify+0x4a3/0x5e0 [nf_tables]
  [ ... ]
  [<ffffffffa05690a8>] nft_do_chain_arp+0x78/0x90 [nf_tables_arp]
  [<ffffffff816f4aa2>] nf_iterate+0x62/0x80
  [<ffffffff816f4b33>] nf_hook_slow+0x73/0xd0
  [<ffffffff81732bbf>] arp_xmit+0x8f/0xb0
  [ ... ]
  [<ffffffff81732d36>] arp_solicit+0x106/0x2c0

So before we use pkt->xt.thoff, check the tprot_set first.

Signed-off-by: Liping Zhang <liping.zhang@spreadtrum.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2016-09-23 09:30:26 +02:00

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/*
* 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/if_vlan.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>
/* add vlan header into the user buffer for if tag was removed by offloads */
static bool
nft_payload_copy_vlan(u32 *d, const struct sk_buff *skb, u8 offset, u8 len)
{
int mac_off = skb_mac_header(skb) - skb->data;
u8 vlan_len, *vlanh, *dst_u8 = (u8 *) d;
struct vlan_ethhdr veth;
vlanh = (u8 *) &veth;
if (offset < ETH_HLEN) {
u8 ethlen = min_t(u8, len, ETH_HLEN - offset);
if (skb_copy_bits(skb, mac_off, &veth, ETH_HLEN))
return false;
veth.h_vlan_proto = skb->vlan_proto;
memcpy(dst_u8, vlanh + offset, ethlen);
len -= ethlen;
if (len == 0)
return true;
dst_u8 += ethlen;
offset = ETH_HLEN;
} else if (offset >= VLAN_ETH_HLEN) {
offset -= VLAN_HLEN;
goto skip;
}
veth.h_vlan_TCI = htons(skb_vlan_tag_get(skb));
veth.h_vlan_encapsulated_proto = skb->protocol;
vlanh += offset;
vlan_len = min_t(u8, len, VLAN_ETH_HLEN - offset);
memcpy(dst_u8, vlanh, vlan_len);
len -= vlan_len;
if (!len)
return true;
dst_u8 += vlan_len;
skip:
return skb_copy_bits(skb, offset + mac_off, dst_u8, len) == 0;
}
static void nft_payload_eval(const struct nft_expr *expr,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
{
const struct nft_payload *priv = nft_expr_priv(expr);
const struct sk_buff *skb = pkt->skb;
u32 *dest = &regs->data[priv->dreg];
int offset;
dest[priv->len / NFT_REG32_SIZE] = 0;
switch (priv->base) {
case NFT_PAYLOAD_LL_HEADER:
if (!skb_mac_header_was_set(skb))
goto err;
if (skb_vlan_tag_present(skb)) {
if (!nft_payload_copy_vlan(dest, skb,
priv->offset, priv->len))
goto err;
return;
}
offset = skb_mac_header(skb) - skb->data;
break;
case NFT_PAYLOAD_NETWORK_HEADER:
offset = skb_network_offset(skb);
break;
case NFT_PAYLOAD_TRANSPORT_HEADER:
if (!pkt->tprot_set)
goto err;
offset = pkt->xt.thoff;
break;
default:
BUG();
}
offset += priv->offset;
if (skb_copy_bits(skb, offset, dest, priv->len) < 0)
goto err;
return;
err:
regs->verdict.code = NFT_BREAK;
}
static const struct nla_policy nft_payload_policy[NFTA_PAYLOAD_MAX + 1] = {
[NFTA_PAYLOAD_SREG] = { .type = NLA_U32 },
[NFTA_PAYLOAD_DREG] = { .type = NLA_U32 },
[NFTA_PAYLOAD_BASE] = { .type = NLA_U32 },
[NFTA_PAYLOAD_OFFSET] = { .type = NLA_U32 },
[NFTA_PAYLOAD_LEN] = { .type = NLA_U32 },
[NFTA_PAYLOAD_CSUM_TYPE] = { .type = NLA_U32 },
[NFTA_PAYLOAD_CSUM_OFFSET] = { .type = NLA_U32 },
};
static int nft_payload_init(const struct nft_ctx *ctx,
const struct nft_expr *expr,
const struct nlattr * const tb[])
{
struct nft_payload *priv = nft_expr_priv(expr);
priv->base = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_BASE]));
priv->offset = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_OFFSET]));
priv->len = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_LEN]));
priv->dreg = nft_parse_register(tb[NFTA_PAYLOAD_DREG]);
return nft_validate_register_store(ctx, priv->dreg, NULL,
NFT_DATA_VALUE, priv->len);
}
static int nft_payload_dump(struct sk_buff *skb, const struct nft_expr *expr)
{
const struct nft_payload *priv = nft_expr_priv(expr);
if (nft_dump_register(skb, NFTA_PAYLOAD_DREG, priv->dreg) ||
nla_put_be32(skb, NFTA_PAYLOAD_BASE, htonl(priv->base)) ||
nla_put_be32(skb, NFTA_PAYLOAD_OFFSET, htonl(priv->offset)) ||
nla_put_be32(skb, NFTA_PAYLOAD_LEN, htonl(priv->len)))
goto nla_put_failure;
return 0;
nla_put_failure:
return -1;
}
static struct nft_expr_type nft_payload_type;
static const struct nft_expr_ops nft_payload_ops = {
.type = &nft_payload_type,
.size = NFT_EXPR_SIZE(sizeof(struct nft_payload)),
.eval = nft_payload_eval,
.init = nft_payload_init,
.dump = nft_payload_dump,
};
const struct nft_expr_ops nft_payload_fast_ops = {
.type = &nft_payload_type,
.size = NFT_EXPR_SIZE(sizeof(struct nft_payload)),
.eval = nft_payload_eval,
.init = nft_payload_init,
.dump = nft_payload_dump,
};
static void nft_payload_set_eval(const struct nft_expr *expr,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
{
const struct nft_payload_set *priv = nft_expr_priv(expr);
struct sk_buff *skb = pkt->skb;
const u32 *src = &regs->data[priv->sreg];
int offset, csum_offset;
__wsum fsum, tsum;
__sum16 sum;
switch (priv->base) {
case NFT_PAYLOAD_LL_HEADER:
if (!skb_mac_header_was_set(skb))
goto err;
offset = skb_mac_header(skb) - skb->data;
break;
case NFT_PAYLOAD_NETWORK_HEADER:
offset = skb_network_offset(skb);
break;
case NFT_PAYLOAD_TRANSPORT_HEADER:
if (!pkt->tprot_set)
goto err;
offset = pkt->xt.thoff;
break;
default:
BUG();
}
csum_offset = offset + priv->csum_offset;
offset += priv->offset;
if (priv->csum_type == NFT_PAYLOAD_CSUM_INET &&
(priv->base != NFT_PAYLOAD_TRANSPORT_HEADER ||
skb->ip_summed != CHECKSUM_PARTIAL)) {
if (skb_copy_bits(skb, csum_offset, &sum, sizeof(sum)) < 0)
goto err;
fsum = skb_checksum(skb, offset, priv->len, 0);
tsum = csum_partial(src, priv->len, 0);
sum = csum_fold(csum_add(csum_sub(~csum_unfold(sum), fsum),
tsum));
if (sum == 0)
sum = CSUM_MANGLED_0;
if (!skb_make_writable(skb, csum_offset + sizeof(sum)) ||
skb_store_bits(skb, csum_offset, &sum, sizeof(sum)) < 0)
goto err;
}
if (!skb_make_writable(skb, max(offset + priv->len, 0)) ||
skb_store_bits(skb, offset, src, priv->len) < 0)
goto err;
return;
err:
regs->verdict.code = NFT_BREAK;
}
static int nft_payload_set_init(const struct nft_ctx *ctx,
const struct nft_expr *expr,
const struct nlattr * const tb[])
{
struct nft_payload_set *priv = nft_expr_priv(expr);
priv->base = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_BASE]));
priv->offset = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_OFFSET]));
priv->len = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_LEN]));
priv->sreg = nft_parse_register(tb[NFTA_PAYLOAD_SREG]);
if (tb[NFTA_PAYLOAD_CSUM_TYPE])
priv->csum_type =
ntohl(nla_get_be32(tb[NFTA_PAYLOAD_CSUM_TYPE]));
if (tb[NFTA_PAYLOAD_CSUM_OFFSET])
priv->csum_offset =
ntohl(nla_get_be32(tb[NFTA_PAYLOAD_CSUM_OFFSET]));
switch (priv->csum_type) {
case NFT_PAYLOAD_CSUM_NONE:
case NFT_PAYLOAD_CSUM_INET:
break;
default:
return -EOPNOTSUPP;
}
return nft_validate_register_load(priv->sreg, priv->len);
}
static int nft_payload_set_dump(struct sk_buff *skb, const struct nft_expr *expr)
{
const struct nft_payload_set *priv = nft_expr_priv(expr);
if (nft_dump_register(skb, NFTA_PAYLOAD_SREG, priv->sreg) ||
nla_put_be32(skb, NFTA_PAYLOAD_BASE, htonl(priv->base)) ||
nla_put_be32(skb, NFTA_PAYLOAD_OFFSET, htonl(priv->offset)) ||
nla_put_be32(skb, NFTA_PAYLOAD_LEN, htonl(priv->len)) ||
nla_put_be32(skb, NFTA_PAYLOAD_CSUM_TYPE, htonl(priv->csum_type)) ||
nla_put_be32(skb, NFTA_PAYLOAD_CSUM_OFFSET,
htonl(priv->csum_offset)))
goto nla_put_failure;
return 0;
nla_put_failure:
return -1;
}
static const struct nft_expr_ops nft_payload_set_ops = {
.type = &nft_payload_type,
.size = NFT_EXPR_SIZE(sizeof(struct nft_payload_set)),
.eval = nft_payload_set_eval,
.init = nft_payload_set_init,
.dump = nft_payload_set_dump,
};
static const struct nft_expr_ops *
nft_payload_select_ops(const struct nft_ctx *ctx,
const struct nlattr * const tb[])
{
enum nft_payload_bases base;
unsigned int offset, len;
if (tb[NFTA_PAYLOAD_BASE] == NULL ||
tb[NFTA_PAYLOAD_OFFSET] == NULL ||
tb[NFTA_PAYLOAD_LEN] == NULL)
return ERR_PTR(-EINVAL);
base = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_BASE]));
switch (base) {
case NFT_PAYLOAD_LL_HEADER:
case NFT_PAYLOAD_NETWORK_HEADER:
case NFT_PAYLOAD_TRANSPORT_HEADER:
break;
default:
return ERR_PTR(-EOPNOTSUPP);
}
if (tb[NFTA_PAYLOAD_SREG] != NULL) {
if (tb[NFTA_PAYLOAD_DREG] != NULL)
return ERR_PTR(-EINVAL);
return &nft_payload_set_ops;
}
if (tb[NFTA_PAYLOAD_DREG] == NULL)
return ERR_PTR(-EINVAL);
offset = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_OFFSET]));
len = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_LEN]));
if (len <= 4 && is_power_of_2(len) && IS_ALIGNED(offset, len) &&
base != NFT_PAYLOAD_LL_HEADER)
return &nft_payload_fast_ops;
else
return &nft_payload_ops;
}
static struct nft_expr_type nft_payload_type __read_mostly = {
.name = "payload",
.select_ops = nft_payload_select_ops,
.policy = nft_payload_policy,
.maxattr = NFTA_PAYLOAD_MAX,
.owner = THIS_MODULE,
};
int __init nft_payload_module_init(void)
{
return nft_register_expr(&nft_payload_type);
}
void nft_payload_module_exit(void)
{
nft_unregister_expr(&nft_payload_type);
}
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