LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: cgel.zte@gmail.com
To: kuba@kernel.org
Cc: davem@davemloft.net, yoshfuji@linux-ipv6.org, dsahern@kernel.org,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	Yang Yang <yang.yang29@zte.com.cn>,
	Zeal Robot <zealci@zte.com.cn>
Subject: [PATCH net-next] net: ipv4: add capability check for net administration
Date: Mon, 19 Jul 2021 18:43:28 -0700	[thread overview]
Message-ID: <20210720014328.378868-1-yang.yang29@zte.com.cn> (raw)

From: Yang Yang <yang.yang29@zte.com.cn>

Root in init user namespace can modify /proc/sys/net/ipv4/ip_forward
without CAP_NET_ADMIN, this doesn't follow the principle of
capabilities. For example, let's take a look at netdev_store(),
root can't modify netdev attribute without CAP_NET_ADMIN.
So let's keep the consistency of permission check logic.

Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Yang Yang <yang.yang29@zte.com.cn>
---
 net/ipv4/devinet.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 73721a4448bd..6238ab2dd3d1 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -2424,11 +2424,15 @@ static int devinet_sysctl_forward(struct ctl_table *ctl, int write,
 	int *valp = ctl->data;
 	int val = *valp;
 	loff_t pos = *ppos;
-	int ret = proc_dointvec(ctl, write, buffer, lenp, ppos);
+	struct net *net = ctl->extra2;
+	int ret;
 
-	if (write && *valp != val) {
-		struct net *net = ctl->extra2;
+	if (write && !ns_capable(net->user_ns, CAP_NET_ADMIN))
+		return -EPERM;
+
+	ret = proc_dointvec(ctl, write, buffer, lenp, ppos);
 
+	if (write && *valp != val) {
 		if (valp != &IPV4_DEVCONF_DFLT(net, FORWARDING)) {
 			if (!rtnl_trylock()) {
 				/* Restore the original values before restarting */
-- 
2.25.1


             reply	other threads:[~2021-07-20  1:48 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-20  1:43 cgel.zte [this message]
2021-07-20 14:20 ` patchwork-bot+netdevbpf

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=20210720014328.378868-1-yang.yang29@zte.com.cn \
    --to=cgel.zte@gmail.com \
    --cc=davem@davemloft.net \
    --cc=dsahern@kernel.org \
    --cc=kuba@kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=netdev@vger.kernel.org \
    --cc=yang.yang29@zte.com.cn \
    --cc=yoshfuji@linux-ipv6.org \
    --cc=zealci@zte.com.cn \
    --subject='Re: [PATCH net-next] net: ipv4: add capability check for net administration' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).