[PATCH net-next] net: ipv4: add capability check for net administration
From: <hidden>
Date: 2021-07-20 01:48:30
Also in:
lkml
Subsystem:
networking [general], networking [ipv4/ipv6], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, David Ahern, Ido Schimmel, Linus Torvalds
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 <redacted> 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 */
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2.25.1