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authorYang Yang <yang.yang29@zte.com.cn>2021-07-19 18:43:28 -0700
committerDavid S. Miller <davem@davemloft.net>2021-07-20 07:15:22 -0700
commit8292d7f6e8712381a828eac2a19a610ce680c4dd (patch)
tree0ef685d728205720d2c4f58e95249788d1688b48
parentb79c6fba6cd7c49a7dbea9999e182f74cca63e19 (diff)
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>
-rw-r--r--net/ipv4/devinet.c10
1 files changed, 7 insertions, 3 deletions
diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index d38124bd1b94..94b648d9eaff 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 */