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route/addr: only sent IFA_FLAGS when needed to workaround picky older kernels

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Older kernels don't accept receiving unknown netlink attributes.
See net/core/rtnetlink.c, rtnetlink_rcv_msg(). This was fixed by kernel
commit 661d2967b3f1b34eeaa7e212e7b9bbe8ee072b59.

As a workaround, only set the additional attributes, when the user
provided flags that makes this necessary and useful.

https://github.com/thom311/libnl/issues/56
https://bugzilla.redhat.com/show_bug.cgi?id=1063885

Based-on-patch-by: Pavel Kankovsky <peak@argo.troja.mff.cuni.cz>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: Thomas Haller <thaller@redhat.com>
This commit is contained in:
Thomas Haller 2014-04-03 18:09:51 +02:00
parent 34bfce6215
commit 5206c05050
1 changed files with 13 additions and 1 deletions
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14
lib/route/addr.c
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@ -598,7 +598,19 @@ static int build_addr_msg(struct rtnl_addr *tmpl, int cmd, int flags,
NLA_PUT(msg, IFA_CACHEINFO, sizeof(ca), &ca);
}
NLA_PUT_U32(msg, IFA_FLAGS, tmpl->a_flags);
if (tmpl->a_flags & ~0xFF) {
/* only set the IFA_FLAGS attribute, if they actually contain additional
* flags that are not already set to am.ifa_flags.
*
* Older kernels refuse RTM_NEWADDR and RTM_NEWROUTE messages with EINVAL
* if they contain unknown netlink attributes. See net/core/rtnetlink.c, which
* was fixed by kernel commit 661d2967b3f1b34eeaa7e212e7b9bbe8ee072b59.
*
* With this workaround, libnl will function correctly with older kernels,
* unless there is a new libnl user that wants to set these flags. In this
* case it's up to the user to workaround this issue. */
NLA_PUT_U32(msg, IFA_FLAGS, tmpl->a_flags);
}
*result = msg;
return 0;