From: ebiederm@xmission•com (Eric W. Biederman)
To: Roopa Prabhu <roopa@cumulusnetworks•com>
Cc: stephen@networkplumber•org, davem@davemloft•net,
rshearma@brocade•com, netdev@vger•kernel.org,
vivek@cumulusnetworks•com
Subject: Re: [PATCH net v3 2/2] mpls: fix mpls route deletes to not check for route scope
Date: Tue, 02 Jun 2015 16:13:51 -0500 [thread overview]
Message-ID: <87a8wholtc.fsf@x220.int.ebiederm.org> (raw)
In-Reply-To: <1433226567-23302-3-git-send-email-roopa@cumulusnetworks.com> (Roopa Prabhu's message of "Mon, 1 Jun 2015 23:29:27 -0700")
Roopa Prabhu <roopa@cumulusnetworks•com> writes:
> From: Roopa Prabhu <roopa@cumulusnetworks•com>
>
> Ignore scope for route del messages
So I just stopped and looked at what is happening. When you originally
reported this you said (or at least I understood) that rtm_scope was not
being set in iproute. I assumed that meant it was not being touched
and it was taking a default value of zero (or else it was possibly
floating). Having looked neither is true. iproute sets rtm_scope
to RT_SCOPE_NOWHERE during delete deliberately to act as a wild card.
In the kernel in other protocols currently ipv4 treats RT_SCOPE_NOWHERE
as a wild card during delete, decnet treats RT_SCOPE_NOWHERE as a wild
card during delete, the remaining protocols (ipv6, phonet, and can) that
implement RTM_DELROUTE do not look at rtm_scope at all. Further ipv6
and phonet set rtm_scope to RT_SCOPE_UNIVERSE when dumped.
Which says to me that we have semantics in the kernel that no one has
let userspace know about, and that scares me when there is a
misunderstanding between the kernel and userspace about what fields
mean. That inevitabily leads to bugs. The kind of bugs that I have
to create security fixes for recently.
So I really think we should fix this in userspace so that that someone
reading iproute will have a chance at knowing that this scopes do not
exist in ipv6 and mpls and that scope logic is just noise in those
cases.
Something like:
>From 837dddea49af874fe750ab0712b3ef8066a2f55a Mon Sep 17 00:00:00 2001
From: "Eric W. Biederman" <ebiederm@xmission•com>
Date: Tue, 2 Jun 2015 15:51:31 -0500
Subject: [PATCH] iproute: When deleting routes don't always set the scope to RT_SCOPE_NOWHERE
IPv6 and MPLS do not implement scopes on addresses and using
RT_SCOPE_NOWHERE is just confusing noise. Use RT_SCOPE_UNIVERSE
instead so that it is clear what is actually happening in the code.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission•com>
---
ip/iproute.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/ip/iproute.c b/ip/iproute.c
index fba475f65314..e9b991fdf62f 100644
--- a/ip/iproute.c
+++ b/ip/iproute.c
@@ -1136,6 +1136,9 @@ static int iproute_modify(int cmd, unsigned flags, int argc, char **argv)
if (nhs_ok)
parse_nexthops(&req.n, &req.r, argc, argv);
+ if (req.r.rtm_family == AF_UNSPEC)
+ req.r.rtm_family = AF_INET;
+
if (!table_ok) {
if (req.r.rtm_type == RTN_LOCAL ||
req.r.rtm_type == RTN_BROADCAST ||
@@ -1144,7 +1147,10 @@ static int iproute_modify(int cmd, unsigned flags, int argc, char **argv)
req.r.rtm_table = RT_TABLE_LOCAL;
}
if (!scope_ok) {
- if (req.r.rtm_type == RTN_LOCAL ||
+ if (req.r.rtm_family == AF_INET6 ||
+ req.r.rtm_family == AF_MPLS)
+ req.r.rtm_scope = RT_SCOPE_UNIVERSE;
+ else if (req.r.rtm_type == RTN_LOCAL ||
req.r.rtm_type == RTN_NAT)
req.r.rtm_scope = RT_SCOPE_HOST;
else if (req.r.rtm_type == RTN_BROADCAST ||
@@ -1160,9 +1166,6 @@ static int iproute_modify(int cmd, unsigned flags, int argc, char **argv)
}
}
- if (req.r.rtm_family == AF_UNSPEC)
- req.r.rtm_family = AF_INET;
-
if (rtnl_talk(&rth, &req.n, NULL, 0) < 0)
return -2;
--
2.2.1
next prev parent reply other threads:[~2015-06-02 21:18 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-02 6:29 [PATCH net v3 2/2] mpls: fix mpls route deletes to not check for route scope Roopa Prabhu
2015-06-02 21:13 ` Eric W. Biederman [this message]
2015-06-02 22:03 ` roopa
2015-06-02 22:59 ` Eric W. Biederman
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87a8wholtc.fsf@x220.int.ebiederm.org \
--to=ebiederm@xmission$(echo .)com \
--cc=davem@davemloft$(echo .)net \
--cc=netdev@vger$(echo .)kernel.org \
--cc=roopa@cumulusnetworks$(echo .)com \
--cc=rshearma@brocade$(echo .)com \
--cc=stephen@networkplumber$(echo .)org \
--cc=vivek@cumulusnetworks$(echo .)com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox