From: Pablo Neira Ayuso pablo@netfilter.org
[ Upstream commit d701d8117200399d85e63a737d2e4e897932f3b6 ]
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 Signed-off-by: Sasha Levin sashal@kernel.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 7344ec7fff2a7..8281656808aee 100644 --- a/net/netfilter/nft_compat.c +++ b/net/netfilter/nft_compat.c @@ -291,6 +291,24 @@ nft_target_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr) module_put(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; @@ -298,7 +316,8 @@ 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; @@ -534,7 +553,8 @@ 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;