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authorPablo Neira Ayuso <pablo@netfilter.org>2018-10-09 20:06:36 +0200
committerPablo Neira Ayuso <pablo@netfilter.org>2018-10-11 11:29:53 +0200
commitd701d8117200399d85e63a737d2e4e897932f3b6 (patch)
tree7a3d7c8160dda988d6c0f2b52f9cd6ca576dd15b /net/netfilter/nft_compat.c
parent18c0ab87364ac5128a152055fdcb1d27e01caf01 (diff)
netfilter: nft_compat: do not dump private area
Zero pad private area, otherwise we expose private kernel pointer to userspace. This patch also zeroes the tail area after the ->matchsize and ->targetsize that results from XT_ALIGN(). Fixes: 0ca743a55991 ("netfilter: nf_tables: add compatibility layer for x_tables") Reported-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net/netfilter/nft_compat.c')
-rw-r--r--net/netfilter/nft_compat.c24
1 files changed, 22 insertions, 2 deletions
diff --git a/net/netfilter/nft_compat.c b/net/netfilter/nft_compat.c
index 32535eea51b2..768292eac2a4 100644
--- a/net/netfilter/nft_compat.c
+++ b/net/netfilter/nft_compat.c
@@ -290,6 +290,24 @@ nft_target_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
module_put(target->me);
}
+static int nft_extension_dump_info(struct sk_buff *skb, int attr,
+ const void *info,
+ unsigned int size, unsigned int user_size)
+{
+ unsigned int info_size, aligned_size = XT_ALIGN(size);
+ struct nlattr *nla;
+
+ nla = nla_reserve(skb, attr, aligned_size);
+ if (!nla)
+ return -1;
+
+ info_size = user_size ? : size;
+ memcpy(nla_data(nla), info, info_size);
+ memset(nla_data(nla) + info_size, 0, aligned_size - info_size);
+
+ return 0;
+}
+
static int nft_target_dump(struct sk_buff *skb, const struct nft_expr *expr)
{
const struct xt_target *target = expr->ops->data;
@@ -297,7 +315,8 @@ static int nft_target_dump(struct sk_buff *skb, const struct nft_expr *expr)
if (nla_put_string(skb, NFTA_TARGET_NAME, target->name) ||
nla_put_be32(skb, NFTA_TARGET_REV, htonl(target->revision)) ||
- nla_put(skb, NFTA_TARGET_INFO, XT_ALIGN(target->targetsize), info))
+ nft_extension_dump_info(skb, NFTA_TARGET_INFO, info,
+ target->targetsize, target->usersize))
goto nla_put_failure;
return 0;
@@ -532,7 +551,8 @@ static int __nft_match_dump(struct sk_buff *skb, const struct nft_expr *expr,
if (nla_put_string(skb, NFTA_MATCH_NAME, match->name) ||
nla_put_be32(skb, NFTA_MATCH_REV, htonl(match->revision)) ||
- nla_put(skb, NFTA_MATCH_INFO, XT_ALIGN(match->matchsize), info))
+ nft_extension_dump_info(skb, NFTA_MATCH_INFO, info,
+ match->matchsize, match->usersize))
goto nla_put_failure;
return 0;