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Commit 9354e0ac authored by Maciej Żenczykowski's avatar Maciej Żenczykowski Committed by Greg Kroah-Hartman
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net: ipv6: support reporting otherwise unknown prefix flags in RTM_NEWPREFIX 



[ Upstream commit bd4a816752bab609dd6d65ae021387beb9e2ddbd ]

Lorenzo points out that we effectively clear all unknown
flags from PIO when copying them to userspace in the netlink
RTM_NEWPREFIX notification.

We could fix this one at a time as new flags are defined,
or in one fell swoop - I choose the latter.

We could either define 6 new reserved flags (reserved1..6) and handle
them individually (and rename them as new flags are defined), or we
could simply copy the entire unmodified byte over - I choose the latter.

This unfortunately requires some anonymous union/struct magic,
so we add a static assert on the struct size for a little extra safety.

Cc: David Ahern <dsahern@kernel.org>
Cc: Lorenzo Colitti <lorenzo@google.com>
Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Signed-off-by: default avatarMaciej Żenczykowski <maze@google.com>
Reviewed-by: default avatarDavid Ahern <dsahern@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 053220aa

include/net/addrconf.h

+10 −2
Original line number Diff line number Diff line
@@ -31,6 +31,9 @@ struct prefix_info { 
	__u8			length;

	__u8			prefix_len;



	union __packed {

		__u8		flags;

		struct __packed {

#if defined(__BIG_ENDIAN_BITFIELD)

			__u8	onlink : 1,

			 	autoconf : 1,
@@ -42,6 +45,8 @@ struct prefix_info { 
#else

#error "Please fix <asm/byteorder.h>"

#endif

		};

	};

	__be32			valid;

	__be32			prefered;

	__be32			reserved2;
@@ -49,6 +54,9 @@ struct prefix_info { 
	struct in6_addr		prefix;

};



/* rfc4861 4.6.2: IPv6 PIO is 32 bytes in size */

static_assert(sizeof(struct prefix_info) == 32);



#include <linux/ipv6.h>

#include <linux/netdevice.h>

#include <net/if_inet6.h>

include/net/if_inet6.h

+0 −4
Original line number Diff line number Diff line
@@ -22,10 +22,6 @@ 
#define IF_RS_SENT	0x10

#define IF_READY	0x80000000



/* prefix flags */

#define IF_PREFIX_ONLINK	0x01

#define IF_PREFIX_AUTOCONF	0x02



enum {

	INET6_IFADDR_STATE_PREDAD,

	INET6_IFADDR_STATE_DAD,

net/ipv6/addrconf.c

+1 −5
Original line number Diff line number Diff line
@@ -5977,11 +5977,7 @@ static int inet6_fill_prefix(struct sk_buff *skb, struct inet6_dev *idev, 
	pmsg->prefix_len = pinfo->prefix_len;

	pmsg->prefix_type = pinfo->type;

	pmsg->prefix_pad3 = 0;

	pmsg->prefix_flags = 0;

	if (pinfo->onlink)

		pmsg->prefix_flags |= IF_PREFIX_ONLINK;

	if (pinfo->autoconf)

		pmsg->prefix_flags |= IF_PREFIX_AUTOCONF;

	pmsg->prefix_flags = pinfo->flags;



	if (nla_put(skb, PREFIX_ADDRESS, sizeof(pinfo->prefix), &pinfo->prefix))

		goto nla_put_failure;