[PATCH net-next] net: sched: remove duplicate check of user rights in qdisc

[PATCH net-next] net: sched: remove duplicate check of user rights in qdisc

[Zhengchao Shao]

In rtnetlink_rcv_msg function, the permission for all user operations
is checked except the GET operation, which is the same as the checking
in qdisc. Therefore, remove the user rights check in qdisc.

Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
---
 net/sched/act_api.c |  4 ----
 net/sched/cls_api.c | 10 ----------
 net/sched/sch_api.c | 11 -----------
 3 files changed, 25 deletions(-)

diff --git a/net/sched/act_api.c b/net/sched/act_api.c
index 817065aa2833..b69fcde546ba 100644
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -1993,10 +1993,6 @@ static int tc_ctl_action(struct sk_buff *skb, struct nlmsghdr *n,
 	u32 flags = 0;
 	int ret = 0;
 
-	if ((n->nlmsg_type != RTM_GETACTION) &&
-	    !netlink_capable(skb, CAP_NET_ADMIN))
-		return -EPERM;
-
 	ret = nlmsg_parse_deprecated(n, sizeof(struct tcamsg), tca,
 				     TCA_ROOT_MAX, NULL, extack);
 	if (ret < 0)
diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index 790d6809be81..1ebab4b11262 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -1977,9 +1977,6 @@ static int tc_new_tfilter(struct sk_buff *skb, struct nlmsghdr *n,
 	bool rtnl_held = false;
 	u32 flags;
 
-	if (!netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN))
-		return -EPERM;
-
 replay:
 	tp_created = 0;
 
@@ -2208,9 +2205,6 @@ static int tc_del_tfilter(struct sk_buff *skb, struct nlmsghdr *n,
 	int err;
 	bool rtnl_held = false;
 
-	if (!netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN))
-		return -EPERM;
-
 	err = nlmsg_parse_deprecated(n, sizeof(*t), tca, TCA_MAX,
 				     rtm_tca_policy, extack);
 	if (err < 0)
@@ -2826,10 +2820,6 @@ static int tc_ctl_chain(struct sk_buff *skb, struct nlmsghdr *n,
 	unsigned long cl;
 	int err;
 
-	if (n->nlmsg_type != RTM_GETCHAIN &&
-	    !netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN))
-		return -EPERM;
-
 replay:
 	q = NULL;
 	err = nlmsg_parse_deprecated(n, sizeof(*t), tca, TCA_MAX,
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index bf87b50837a8..6c687e77d68b 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -1424,10 +1424,6 @@ static int tc_get_qdisc(struct sk_buff *skb, struct nlmsghdr *n,
 	struct Qdisc *p = NULL;
 	int err;
 
-	if ((n->nlmsg_type != RTM_GETQDISC) &&
-	    !netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN))
-		return -EPERM;
-
 	err = nlmsg_parse_deprecated(n, sizeof(*tcm), tca, TCA_MAX,
 				     rtm_tca_policy, extack);
 	if (err < 0)
@@ -1508,9 +1504,6 @@ static int tc_modify_qdisc(struct sk_buff *skb, struct nlmsghdr *n,
 	struct Qdisc *q, *p;
 	int err;
 
-	if (!netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN))
-		return -EPERM;
-
 replay:
 	/* Reinit, just in case something touches this. */
 	err = nlmsg_parse_deprecated(n, sizeof(*tcm), tca, TCA_MAX,
@@ -1992,10 +1985,6 @@ static int tc_ctl_tclass(struct sk_buff *skb, struct nlmsghdr *n,
 	u32 qid;
 	int err;
 
-	if ((n->nlmsg_type != RTM_GETTCLASS) &&
-	    !netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN))
-		return -EPERM;
-
 	err = nlmsg_parse_deprecated(n, sizeof(*tcm), tca, TCA_MAX,
 				     rtm_tca_policy, extack);
 	if (err < 0)
-- 
2.17.1

Re: [PATCH net-next] net: sched: remove duplicate check of user rights in qdisc

[Jakub Kicinski]

On Thu, 18 Aug 2022 15:25:00 +0800 Zhengchao Shao wrote:
> -	if ((n->nlmsg_type != RTM_GETACTION) &&
> -	    !netlink_capable(skb, CAP_NET_ADMIN))
> -		return -EPERM;

This check is not network namespace capable, right?

We're probably fine making it namespace aware but it needs to be a
separate change.

Re: [PATCH net-next] net: sched: remove duplicate check of user rights in qdisc

[shaozhengchao]

On 2022/8/19 11:44, Jakub Kicinski wrote:
> On Thu, 18 Aug 2022 15:25:00 +0800 Zhengchao Shao wrote:
>> -	if ((n->nlmsg_type != RTM_GETACTION) &&
>> -	    !netlink_capable(skb, CAP_NET_ADMIN))
>> -		return -EPERM;
> 
> This check is not network namespace capable, right?
> 
> We're probably fine making it namespace aware but it needs to be a
> separate change.

Hi Jakub:
	Thank you for your reply. I will add the wrong deletion back in V2. And 
I will also consider to make checking namespace aware in action function.

Zhengchao Shao