[PATCH 5/8] netfilter: nft_compat: do not dump private area
From: Pablo Neira Ayuso <pablo@netfilter.org>
Date: 2018-10-23 04:27:38
Also in:
netfilter-devel
Subsystem:
netfilter, networking [general], the rest · Maintainers:
Pablo Neira Ayuso, Florian Westphal, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
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>
---
net/netfilter/nft_compat.c | 24 ++++++++++++++++++++++--
1 file 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;
--
2.11.0