* [PATCH net] uapi: linux: restore IPPROTO_MAX to 256
@ 2023-01-11 21:47 Pablo Neira Ayuso
2023-01-12 10:54 ` Pablo Neira Ayuso
0 siblings, 1 reply; 2+ messages in thread
From: Pablo Neira Ayuso @ 2023-01-11 21:47 UTC (permalink / raw)
To: netfilter-devel; +Cc: davem, netdev, kuba, pabeni, edumazet
IPPROTO_MAX used to be 256, but with the introduction of IPPROTO_MPTCP
definition, IPPROTO_MAX was bumped to 263.
IPPROTO_MPTCP definition is used for the socket interface from
userspace. It is never used in the layer 4 protocol field of
IP headers.
IPPROTO_* definitions are used anywhere in the kernel as well as in
userspace to set the layer 4 protocol field in IP headers.
At least in Netfilter, there is code in userspace that relies on
IPPROTO_MAX (not inclusive) to check for the maximum layer 4 protocol.
This patch restores IPPROTO_MAX to 256.
Fixes: faf391c3826c ("tcp: Define IPPROTO_MPTCP")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
Alternatively, I can also define an internal __IPPROTO_MAX to 256 in
userspace. I understand an update on uapi at this stage might be
complicated. Another possibility is to add a new definition
IPPROTO_FIELD_MAX to uapi and set it to 256 that userspace could start
using.
include/uapi/linux/in.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/uapi/linux/in.h b/include/uapi/linux/in.h
index 07a4cb149305..0600b03b49ee 100644
--- a/include/uapi/linux/in.h
+++ b/include/uapi/linux/in.h
@@ -80,10 +80,10 @@ enum {
IPPROTO_ETHERNET = 143, /* Ethernet-within-IPv6 Encapsulation */
#define IPPROTO_ETHERNET IPPROTO_ETHERNET
IPPROTO_RAW = 255, /* Raw IP packets */
+ IPPROTO_MAX = 256,
#define IPPROTO_RAW IPPROTO_RAW
IPPROTO_MPTCP = 262, /* Multipath TCP connection */
#define IPPROTO_MPTCP IPPROTO_MPTCP
- IPPROTO_MAX
};
#endif
--
2.30.2
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH net] uapi: linux: restore IPPROTO_MAX to 256
2023-01-11 21:47 [PATCH net] uapi: linux: restore IPPROTO_MAX to 256 Pablo Neira Ayuso
@ 2023-01-12 10:54 ` Pablo Neira Ayuso
0 siblings, 0 replies; 2+ messages in thread
From: Pablo Neira Ayuso @ 2023-01-12 10:54 UTC (permalink / raw)
To: netfilter-devel; +Cc: davem, netdev, kuba, pabeni, edumazet
On Wed, Jan 11, 2023 at 10:47:19PM +0100, Pablo Neira Ayuso wrote:
> IPPROTO_MAX used to be 256, but with the introduction of IPPROTO_MPTCP
> definition, IPPROTO_MAX was bumped to 263.
>
> IPPROTO_MPTCP definition is used for the socket interface from
> userspace. It is never used in the layer 4 protocol field of
> IP headers.
>
> IPPROTO_* definitions are used anywhere in the kernel as well as in
> userspace to set the layer 4 protocol field in IP headers.
>
> At least in Netfilter, there is code in userspace that relies on
> IPPROTO_MAX (not inclusive) to check for the maximum layer 4 protocol.
>
> This patch restores IPPROTO_MAX to 256.
>
> Fixes: faf391c3826c ("tcp: Define IPPROTO_MPTCP")
> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
> ---
> Alternatively, I can also define an internal __IPPROTO_MAX to 256 in
> userspace. I understand an update on uapi at this stage might be
> complicated. Another possibility is to add a new definition
> IPPROTO_FIELD_MAX to uapi and set it to 256 that userspace could start
> using.
Scratch this.
This breaks inet_create() and inet6_create() which is going to break
MP-TCP with socket().
I'll post a v2 adding a new IPPROTO_FIELD_MAX definition 256.
^ permalink raw reply [flat|nested] 2+ messages in thread
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