netdev - [PATCH next] sysctl: expose all net/core sysctls inside netns

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Message-ID: <20221222191005.71787-1-maheshb@google.com>
Date:   Thu, 22 Dec 2022 11:10:05 -0800
From:   Mahesh Bandewar <maheshb@...gle.com>
To:     Netdev <netdev@...r.kernel.org>
Cc:     Mahesh Bandewar <mahesh@...dewar.net>,
        Mahesh Bandewar <maheshb@...gle.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Soheil Hassas Yeganeh <soheil@...gle.com>
Subject: [PATCH next] sysctl: expose all net/core sysctls inside netns

All were not visible to the non-priv users inside netns. However,
with 4ecb90090c84 ("sysctl: allow override of /proc/sys/net with
CAP_NET_ADMIN"), these vars are protected from getting modified.
A proc with capable(CAP_NET_ADMIN) can change the values so
not having them visible inside netns is just causing nuisance to
process that check certain values (e.g. net.core.somaxconn) and
see different behavior in root-netns vs. other-netns

Cc: "David S. Miller" <davem@...emloft.net>
Cc: Eric Dumazet <edumazet@...gle.com>
Cc: Jakub Kicinski <kuba@...nel.org>
Cc: Paolo Abeni <pabeni@...hat.com>
Cc: Soheil Hassas Yeganeh <soheil@...gle.com>
Signed-off-by: Mahesh Bandewar <maheshb@...gle.com>
---
 net/core/sysctl_net_core.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index 5b1ce656baa1..e7b98162c632 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -643,11 +643,6 @@ static __net_init int sysctl_core_net_init(struct net *net)
 
 		for (tmp = tbl; tmp->procname; tmp++)
 			tmp->data += (char *)net - (char *)&init_net;
-
-		/* Don't export any sysctls to unprivileged users */
-		if (net->user_ns != &init_user_ns) {
-			tbl[0].procname = NULL;
-		}
 	}
 
 	net->core.sysctl_hdr = register_net_sysctl(net, "net/core", tbl);
-- 
2.39.0.314.g84b9a713c41-goog