net: Use netlink_ns_capable to verify the permisions of netlink messages

It is possible by passing a netlink socket to a more privileged
executable and then to fool that executable into writing to the socket
data that happens to be valid netlink message to do something that
privileged executable did not intend to do.

To keep this from happening replace bare capable and ns_capable calls
with netlink_capable, netlink_net_calls and netlink_ns_capable calls.
Which act the same as the previous calls except they verify that the
opener of the socket had the desired permissions as well.

Reported-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 5 insertions, 5 deletions

diff --git a/net/sched/act_api.c b/net/sched/act_api.c
index 8a5ba5add4bc..648778aef1a2 100644
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -948,7 +948,7 @@ static int tc_ctl_action(struct sk_buff *skb, struct nlmsghdr *n)
         u32 portid = skb ? NETLINK_CB(skb).portid : 0;
         int ret = 0, ovr = 0;
 
-        if ((n->nlmsg_type != RTM_GETACTION) && !capable(CAP_NET_ADMIN))
+        if ((n->nlmsg_type != RTM_GETACTION) && !netlink_capable(skb, CAP_NET_ADMIN))
                 return -EPERM;
 
         ret = nlmsg_parse(n, sizeof(struct tcamsg), tca, TCA_ACT_MAX, NULL);
diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index 29a30a14c315..bdbdb1a7920a 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -134,7 +134,7 @@ static int tc_ctl_tfilter(struct sk_buff *skb, struct nlmsghdr *n)
         int err;
         int tp_created = 0;
 
-        if ((n->nlmsg_type != RTM_GETTFILTER) && !capable(CAP_NET_ADMIN))
+        if ((n->nlmsg_type != RTM_GETTFILTER) && !netlink_capable(skb, CAP_NET_ADMIN))
                 return -EPERM;
 
 replay:
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index a0b84e0e22de..400769014bbd 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -1084,7 +1084,7 @@ static int tc_get_qdisc(struct sk_buff *skb, struct nlmsghdr *n)
         struct Qdisc *p = NULL;
         int err;
 
-        if ((n->nlmsg_type != RTM_GETQDISC) && !capable(CAP_NET_ADMIN))
+        if ((n->nlmsg_type != RTM_GETQDISC) && !netlink_capable(skb, CAP_NET_ADMIN))
                 return -EPERM;
 
         err = nlmsg_parse(n, sizeof(*tcm), tca, TCA_MAX, NULL);
@@ -1151,7 +1151,7 @@ static int tc_modify_qdisc(struct sk_buff *skb, struct nlmsghdr *n)
         struct Qdisc *q, *p;
         int err;
 
-        if (!capable(CAP_NET_ADMIN))
+        if (!netlink_capable(skb, CAP_NET_ADMIN))
                 return -EPERM;
 
 replay:
@@ -1490,7 +1490,7 @@ static int tc_ctl_tclass(struct sk_buff *skb, struct nlmsghdr *n)
         u32 qid;
         int err;
 
-        if ((n->nlmsg_type != RTM_GETTCLASS) && !capable(CAP_NET_ADMIN))
+        if ((n->nlmsg_type != RTM_GETTCLASS) && !netlink_capable(skb, CAP_NET_ADMIN))
                 return -EPERM;
 
         err = nlmsg_parse(n, sizeof(*tcm), tca, TCA_MAX, NULL);