Commit 8292d7f6 authored Jul 19, 2021 by Yang Yang Committed by David S. Miller Jul 20, 2021

net: ipv4: add capability check for net administration



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>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent b79c6fba

net/ipv4/devinet.c

+7 −3

Original line number	Diff line number	Diff line
		@@ -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);

		if (write && *valp != val) {
		struct net *net = ctl->extra2;
		int ret;

		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 */