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Date: Mon, 20 Oct 2014 10:10:34 +0200
From: Pablo Neira Ayuso <pablo@...filter.org>
To: netfilter-devel@...r.kernel.org
Cc: davem@...emloft.net, netdev@...r.kernel.org
Subject: [PATCH 2/7] netfilter: nf_tables: restrict nat/masq expressions to nat chain type
This adds the missing validation code to avoid the use of nat/masq from
non-nat chains. The validation assumes two possible configuration
scenarios:
1) Use of nat from base chain that is not of nat type. Reject this
configuration from the nft_*_init() path of the expression.
2) Use of nat from non-base chain. In this case, we have to wait until
the non-base chain is referenced by at least one base chain via
jump/goto. This is resolved from the nft_*_validate() path which is
called from nf_tables_check_loops().
The user gets an -EOPNOTSUPP in both cases.
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
include/net/netfilter/nf_tables.h | 3 +++
include/net/netfilter/nft_masq.h | 3 +++
net/ipv4/netfilter/nft_masq_ipv4.c | 1 +
net/ipv6/netfilter/nft_masq_ipv6.c | 1 +
net/netfilter/nf_tables_api.c | 14 ++++++++++++++
net/netfilter/nft_masq.c | 12 ++++++++++++
net/netfilter/nft_nat.c | 12 ++++++++++++
7 files changed, 46 insertions(+)
diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index 3d72923..845c596 100644
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -530,6 +530,9 @@ enum nft_chain_type {
NFT_CHAIN_T_MAX
};
+int nft_chain_validate_dependency(const struct nft_chain *chain,
+ enum nft_chain_type type);
+
struct nft_stats {
u64 bytes;
u64 pkts;
diff --git a/include/net/netfilter/nft_masq.h b/include/net/netfilter/nft_masq.h
index c72729f..e2a518b 100644
--- a/include/net/netfilter/nft_masq.h
+++ b/include/net/netfilter/nft_masq.h
@@ -13,4 +13,7 @@ int nft_masq_init(const struct nft_ctx *ctx,
int nft_masq_dump(struct sk_buff *skb, const struct nft_expr *expr);
+int nft_masq_validate(const struct nft_ctx *ctx, const struct nft_expr *expr,
+ const struct nft_data **data);
+
#endif /* _NFT_MASQ_H_ */
diff --git a/net/ipv4/netfilter/nft_masq_ipv4.c b/net/ipv4/netfilter/nft_masq_ipv4.c
index 1c636d6..c1023c4 100644
--- a/net/ipv4/netfilter/nft_masq_ipv4.c
+++ b/net/ipv4/netfilter/nft_masq_ipv4.c
@@ -39,6 +39,7 @@ static const struct nft_expr_ops nft_masq_ipv4_ops = {
.eval = nft_masq_ipv4_eval,
.init = nft_masq_init,
.dump = nft_masq_dump,
+ .validate = nft_masq_validate,
};
static struct nft_expr_type nft_masq_ipv4_type __read_mostly = {
diff --git a/net/ipv6/netfilter/nft_masq_ipv6.c b/net/ipv6/netfilter/nft_masq_ipv6.c
index 556262f..8a7ac68 100644
--- a/net/ipv6/netfilter/nft_masq_ipv6.c
+++ b/net/ipv6/netfilter/nft_masq_ipv6.c
@@ -39,6 +39,7 @@ static const struct nft_expr_ops nft_masq_ipv6_ops = {
.eval = nft_masq_ipv6_eval,
.init = nft_masq_init,
.dump = nft_masq_dump,
+ .validate = nft_masq_validate,
};
static struct nft_expr_type nft_masq_ipv6_type __read_mostly = {
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 556a0df..65eb2a1 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -3744,6 +3744,20 @@ static const struct nfnetlink_subsystem nf_tables_subsys = {
.abort = nf_tables_abort,
};
+int nft_chain_validate_dependency(const struct nft_chain *chain,
+ enum nft_chain_type type)
+{
+ const struct nft_base_chain *basechain;
+
+ if (chain->flags & NFT_BASE_CHAIN) {
+ basechain = nft_base_chain(chain);
+ if (basechain->type->type != type)
+ return -EOPNOTSUPP;
+ }
+ return 0;
+}
+EXPORT_SYMBOL_GPL(nft_chain_validate_dependency);
+
/*
* Loop detection - walk through the ruleset beginning at the destination chain
* of a new jump until either the source chain is reached (loop) or all
diff --git a/net/netfilter/nft_masq.c b/net/netfilter/nft_masq.c
index 6637bab..d1ffd5e 100644
--- a/net/netfilter/nft_masq.c
+++ b/net/netfilter/nft_masq.c
@@ -26,6 +26,11 @@ int nft_masq_init(const struct nft_ctx *ctx,
const struct nlattr * const tb[])
{
struct nft_masq *priv = nft_expr_priv(expr);
+ int err;
+
+ err = nft_chain_validate_dependency(ctx->chain, NFT_CHAIN_T_NAT);
+ if (err < 0)
+ return err;
if (tb[NFTA_MASQ_FLAGS] == NULL)
return 0;
@@ -55,5 +60,12 @@ nla_put_failure:
}
EXPORT_SYMBOL_GPL(nft_masq_dump);
+int nft_masq_validate(const struct nft_ctx *ctx, const struct nft_expr *expr,
+ const struct nft_data **data)
+{
+ return nft_chain_validate_dependency(ctx->chain, NFT_CHAIN_T_NAT);
+}
+EXPORT_SYMBOL_GPL(nft_masq_validate);
+
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Arturo Borrero Gonzalez <arturo.borrero.glez@...il.com>");
diff --git a/net/netfilter/nft_nat.c b/net/netfilter/nft_nat.c
index 799550b..0f0af6e 100644
--- a/net/netfilter/nft_nat.c
+++ b/net/netfilter/nft_nat.c
@@ -95,6 +95,10 @@ static int nft_nat_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
u32 family;
int err;
+ err = nft_chain_validate_dependency(ctx->chain, NFT_CHAIN_T_NAT);
+ if (err < 0)
+ return err;
+
if (tb[NFTA_NAT_TYPE] == NULL)
return -EINVAL;
@@ -205,6 +209,13 @@ nla_put_failure:
return -1;
}
+static int nft_nat_validate(const struct nft_ctx *ctx,
+ const struct nft_expr *expr,
+ const struct nft_data **data)
+{
+ return nft_chain_validate_dependency(ctx->chain, NFT_CHAIN_T_NAT);
+}
+
static struct nft_expr_type nft_nat_type;
static const struct nft_expr_ops nft_nat_ops = {
.type = &nft_nat_type,
@@ -212,6 +223,7 @@ static const struct nft_expr_ops nft_nat_ops = {
.eval = nft_nat_eval,
.init = nft_nat_init,
.dump = nft_nat_dump,
+ .validate = nft_nat_validate,
};
static struct nft_expr_type nft_nat_type __read_mostly = {
--
1.7.10.4
--
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