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| author | Pablo Neira Ayuso <pablo@netfilter.org> | 2018-10-09 20:06:36 +0200 |
|---|---|---|
| committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2018-10-11 11:29:53 +0200 |
| commit | d701d8117200399d85e63a737d2e4e897932f3b6 (patch) | |
| tree | 7a3d7c8160dda988d6c0f2b52f9cd6ca576dd15b | |
| parent | 18c0ab87364ac5128a152055fdcb1d27e01caf01 (diff) | |
| download | linux-d701d8117200399d85e63a737d2e4e897932f3b6.tar.gz linux-d701d8117200399d85e63a737d2e4e897932f3b6.tar.bz2 linux-d701d8117200399d85e63a737d2e4e897932f3b6.zip | |
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>
| -rw-r--r-- | net/netfilter/nft_compat.c | 24 |
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; |