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net: ipv4: add capability check for net administration

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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>
This commit is contained in:
Yang Yang 2021-07-19 18:43:28 -07:00 committed by David S. Miller
parent b79c6fba6c
commit 8292d7f6e8
1 changed files with 7 additions and 3 deletions
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10
net/ipv4/devinet.c
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@ -2424,11 +2424,15 @@ static int devinet_sysctl_forward(struct ctl_table *ctl, int write,
int *valp = ctl->data; int *valp = ctl->data;
int val = *valp; int val = *valp;
loff_t pos = *ppos; loff_t pos = *ppos;
int ret = proc_dointvec(ctl, write, buffer, lenp, ppos); 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 (write && *valp != val) {
struct net *net = ctl->extra2;
if (valp != &IPV4_DEVCONF_DFLT(net, FORWARDING)) { if (valp != &IPV4_DEVCONF_DFLT(net, FORWARDING)) {
if (!rtnl_trylock()) { if (!rtnl_trylock()) {
/* Restore the original values before restarting */ /* Restore the original values before restarting */