netdev - [PATCH net] ipv6: invert flowlabel sharing check in process and user mode

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Message-Id: <20190425160654.211972-1-willemdebruijn.kernel@gmail.com>
Date:   Thu, 25 Apr 2019 12:06:54 -0400
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, ebiederm@...ssion.com,
        Willem de Bruijn <willemb@...gle.com>
Subject: [PATCH net] ipv6: invert flowlabel sharing check in process and user mode

From: Willem de Bruijn <willemb@...gle.com>

A request for a flowlabel fails in process or user exclusive mode must
fail if the caller pid or uid does not match. Invert the test.

Previously, the test was unsafe wrt PID recycling, but indeed tested
for inequality: fl1->owner != fl->owner

Fixes: 4f82f45730c68 ("net ip6 flowlabel: Make owner a union of struct pid* and kuid_t")
Signed-off-by: Willem de Bruijn <willemb@...gle.com>
---
 net/ipv6/ip6_flowlabel.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ipv6/ip6_flowlabel.c b/net/ipv6/ip6_flowlabel.c
index cb54a8a3c2735..a05036bc808d5 100644
--- a/net/ipv6/ip6_flowlabel.c
+++ b/net/ipv6/ip6_flowlabel.c
@@ -633,9 +633,9 @@ int ipv6_flowlabel_opt(struct sock *sk, char __user *optval, int optlen)
 				if (fl1->share == IPV6_FL_S_EXCL ||
 				    fl1->share != fl->share ||
 				    ((fl1->share == IPV6_FL_S_PROCESS) &&
-				     (fl1->owner.pid == fl->owner.pid)) ||
+				     (fl1->owner.pid != fl->owner.pid)) ||
 				    ((fl1->share == IPV6_FL_S_USER) &&
-				     uid_eq(fl1->owner.uid, fl->owner.uid)))
+				     !uid_eq(fl1->owner.uid, fl->owner.uid)))
 					goto release;
 
 				err = -ENOMEM;
-- 
2.21.0.593.g511ec345e18-goog