Re: [PATCH net-next 1/1] net: Add new protocol attribute to IP addresses

On 2022-02-04 16:16 UTC, David Ahern wrote:

quoted

diff --git a/include/linux/inetdevice.h b/include/linux/inetdevice.h
index a038feb63f23..caa6b7a5b5ac 100644
--- a/include/linux/inetdevice.h
+++ b/include/linux/inetdevice.h

@@ -148,6 +148,7 @@ struct in_ifaddr {
 	unsigned char		ifa_prefixlen;
 	__u32			ifa_flags;
 	char			ifa_label[IFNAMSIZ];
+	unsigned char		ifa_proto;

there is a hole after ifa_prefixlen where this can go and not affect
struct size.

quoted

 
 	/* In seconds, relative to tstamp. Expiry is at tstamp + HZ * lft. */
 	__u32			ifa_valid_lft;

diff --git a/include/net/addrconf.h b/include/net/addrconf.h
index 78ea3e332688..e53d8f4f4166 100644
--- a/include/net/addrconf.h
+++ b/include/net/addrconf.h

@@ -69,6 +69,7 @@ struct ifa6_config {
 	u32			preferred_lft;
 	u32			valid_lft;
 	u16			scope;
+	u8			ifa_proto;
 };
 
 int addrconf_init(void);

diff --git a/include/net/if_inet6.h b/include/net/if_inet6.h
index 653e7d0f65cb..f7c270b24167 100644
--- a/include/net/if_inet6.h
+++ b/include/net/if_inet6.h

@@ -73,6 +73,8 @@ struct inet6_ifaddr {
 
 	struct rcu_head		rcu;
 	struct in6_addr		peer_addr;
+
+	__u8			ifa_proto;

similarly for this struct; couple of holes that you can put this.

Thank you! I will fix this in v2.

quoted

 };
 
 struct ip6_sf_socklist {

diff --git a/include/uapi/linux/if_addr.h b/include/uapi/linux/if_addr.h
index dfcf3ce0097f..2aa46b9c9961 100644
--- a/include/uapi/linux/if_addr.h
+++ b/include/uapi/linux/if_addr.h

@@ -35,6 +35,7 @@ enum {
 	IFA_FLAGS,
 	IFA_RT_PRIORITY,  /* u32, priority/metric for prefix route */
 	IFA_TARGET_NETNSID,
+	IFA_PROTO,
 	__IFA_MAX,
 };
 

@@ -69,4 +70,7 @@ struct ifa_cacheinfo {
 #define IFA_PAYLOAD(n) NLMSG_PAYLOAD(n,sizeof(struct ifaddrmsg))
 #endif
 
+/* ifa_protocol */
+#define IFAPROT_UNSPEC	0

*If* the value is just a passthrough (userspace to kernel and back), no
need for this uapi. However, have you considered builtin protocol labels
- e.g. for autoconf, LLA, etc. Kernel generated vs RAs vs userspace
adding it.

Agreed. For my own (very isolated) use case I only need the passthrough,
but I can see that it would make sense to standardize some labels.
I was trying to give this some thought but I have to admit I copped out
because of my limited knowledge on what labels would be reasonable to
reserve.

Based on what you mention, do you think the list bellow would make sense?

#define IFAPROT_UNSPEC		0  /* unspecified */
#define IFAPROT_KERNEL_LO	1  /* loopback */
#define IFAPROT_KERNEL_RA	2  /* auto assigned by kernel from router announcement */
#define IFAPROT_KERNEL_LL	3  /* link-local set by kernel */
#define IFAPROT_STATIC		4  /* set by admin */
#define IFAPROT_AUTO		5  /* DHCP, BOOTP etc. */
#define IFAPROT_LL		6  /* link-local set by userspace */

Or do you think it needs more granularity?