netdev - [PATCH net-next 1/7] net: skb_reset_mac_len() must check if mac

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20241105174403.850330-2-edumazet@google.com>
Date: Tue,  5 Nov 2024 17:43:57 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, eric.dumazet@...il.com, 
	Eric Dumazet <edumazet@...gle.com>, En-Wei Wu <en-wei.wu@...onical.com>
Subject: [PATCH net-next 1/7] net: skb_reset_mac_len() must check if
 mac_header was set

Recent discussions show that skb_reset_mac_len() should be more careful.

We expect the MAC header being set.

If not, clear skb->mac_len and fire a warning for CONFIG_DEBUG_NET=y builds.

If after investigations we find that not having a MAC header was okay,
we can remove the warning.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Link: https://lore.kernel.org/netdev/CANn89iJZGH+yEfJxfPWa3Hm7jxb-aeY2Up4HufmLMnVuQXt38A@mail.gmail.com/T/
Cc: En-Wei Wu <en-wei.wu@...onical.com>
---
 include/linux/skbuff.h | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 48f1e0fa2a13619e41dfba40f2593dd61f9b9a06..5d8fefa71cac78d83b9565d9038c319112da1e2d 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2909,9 +2909,19 @@ static inline void skb_reset_inner_headers(struct sk_buff *skb)
 	skb->inner_transport_header = skb->transport_header;
 }
 
+static inline int skb_mac_header_was_set(const struct sk_buff *skb)
+{
+	return skb->mac_header != (typeof(skb->mac_header))~0U;
+}
+
 static inline void skb_reset_mac_len(struct sk_buff *skb)
 {
-	skb->mac_len = skb->network_header - skb->mac_header;
+	if (!skb_mac_header_was_set(skb)) {
+		DEBUG_NET_WARN_ON_ONCE(1);
+		skb->mac_len = 0;
+	} else {
+		skb->mac_len = skb->network_header - skb->mac_header;
+	}
 }
 
 static inline unsigned char *skb_inner_transport_header(const struct sk_buff
@@ -3014,11 +3024,6 @@ static inline void skb_set_network_header(struct sk_buff *skb, const int offset)
 	skb->network_header += offset;
 }
 
-static inline int skb_mac_header_was_set(const struct sk_buff *skb)
-{
-	return skb->mac_header != (typeof(skb->mac_header))~0U;
-}
-
 static inline unsigned char *skb_mac_header(const struct sk_buff *skb)
 {
 	DEBUG_NET_WARN_ON_ONCE(!skb_mac_header_was_set(skb));
-- 
2.47.0.199.ga7371fff76-goog