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authorGao Feng <gfree.wind@vip.163.com>2017-05-16 09:30:18 +0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-10-13 09:09:32 +0200
commitab94214d643ed15ea0737db9c04c9c223201f346 (patch)
parent72c6877269634ae6c70112c34c5961e6dd520799 (diff)
ebtables: arpreply: Add the standard target sanity check
commit c953d63548207a085abcb12a15fefc8a11ffdf0a upstream. The info->target comes from userspace and it would be used directly. So we need to add the sanity check to make sure it is a valid standard target, although the ebtables tool has already checked it. Kernel needs to validate anything coming from userspace. If the target is set as an evil value, it would break the ebtables and cause a panic. Because the non-standard target is treated as one offset. Now add one helper function ebt_invalid_target, and we would replace the macro INVALID_TARGET later. Signed-off-by: Gao Feng <gfree.wind@vip.163.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> Cc: Loic <hackurx@opensec.fr> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2 files changed, 8 insertions, 0 deletions
diff --git a/include/linux/netfilter_bridge/ebtables.h b/include/linux/netfilter_bridge/ebtables.h
index 34e7a2b7f867..78cd1b2cd56c 100644
--- a/include/linux/netfilter_bridge/ebtables.h
+++ b/include/linux/netfilter_bridge/ebtables.h
@@ -124,4 +124,9 @@ extern unsigned int ebt_do_table(unsigned int hook, struct sk_buff *skb,
/* True if the target is not a standard target */
#define INVALID_TARGET (info->target < -NUM_STANDARD_TARGETS || info->target >= 0)
+static inline bool ebt_invalid_target(int target)
+ return (target < -NUM_STANDARD_TARGETS || target >= 0);
diff --git a/net/bridge/netfilter/ebt_arpreply.c b/net/bridge/netfilter/ebt_arpreply.c
index 070cf134a22f..f2660c1b29e4 100644
--- a/net/bridge/netfilter/ebt_arpreply.c
+++ b/net/bridge/netfilter/ebt_arpreply.c
@@ -67,6 +67,9 @@ static int ebt_arpreply_tg_check(const struct xt_tgchk_param *par)
if (e->ethproto != htons(ETH_P_ARP) ||
e->invflags & EBT_IPROTO)
return -EINVAL;
+ if (ebt_invalid_target(info->target))
+ return -EINVAL;
return 0;