userns: Convert cls_flow to work with user namespaces enabled (a6c6796c) · Commits · 戴 / test

The flow classifier can use uids and gids of the sockets that are transmitting packets and do insert those uids and gids into the packet classification calcuation. I don't fully understand the details but it appears that we can depend on specific uids and gids when making traffic classification decisions. To work with user namespaces enabled map from kuids and kgids into uids and gids in the initial user namespace giving raw integer values the code can play with and depend on. To avoid issues of userspace depending on uids and gids in packet classifiers installed from other user namespaces and getting confused deny all packet classifiers that use uids or gids that are not comming from a netlink socket in the initial user namespace. Cc: Patrick McHardy <kaber@trash.net> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Jamal Hadi Salim <jhs@mojatatu.com> Cc: Changli Gao <xiaosuo@gmail.com> Acked-by:

David S. Miller <davem@davemloft.net> Acked-by:

Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by:

Eric W. Biederman <ebiederm@xmission.com>

init/Kconfig

+0 −1

Original line number	Diff line number	Diff line
		@@ -943,7 +943,6 @@ config UIDGID_CONVERTED

		# Networking
		depends on NET_9P = n
		depends on NET_CLS_FLOW = n
		depends on NETFILTER_XT_MATCH_OWNER = n
		depends on NETFILTER_XT_MATCH_RECENT = n
		depends on NETFILTER_XT_TARGET_LOG = n

net/sched/cls_flow.c

+12 −4

Original line number	Diff line number	Diff line
		@@ -193,15 +193,19 @@ static u32 flow_get_rtclassid(const struct sk_buff *skb)

		static u32 flow_get_skuid(const struct sk_buff *skb)
		{
		if (skb->sk && skb->sk->sk_socket && skb->sk->sk_socket->file)
		return skb->sk->sk_socket->file->f_cred->fsuid;
		if (skb->sk && skb->sk->sk_socket && skb->sk->sk_socket->file) {
		kuid_t skuid = skb->sk->sk_socket->file->f_cred->fsuid;
		return from_kuid(&init_user_ns, skuid);
		}
		return 0;
		}

		static u32 flow_get_skgid(const struct sk_buff *skb)
		{
		if (skb->sk && skb->sk->sk_socket && skb->sk->sk_socket->file)
		return skb->sk->sk_socket->file->f_cred->fsgid;
		if (skb->sk && skb->sk->sk_socket && skb->sk->sk_socket->file) {
		kgid_t skgid = skb->sk->sk_socket->file->f_cred->fsgid;
		return from_kgid(&init_user_ns, skgid);
		}
		return 0;
		}

		@@ -387,6 +391,10 @@ static int flow_change(struct sk_buff *in_skb,

		if (fls(keymask) - 1 > FLOW_KEY_MAX)
		return -EOPNOTSUPP;

		if ((keymask & (FLOW_KEY_SKUID\|FLOW_KEY_SKGID)) &&
		sk_user_ns(NETLINK_CB(in_skb).ssk) != &init_user_ns)
		return -EOPNOTSUPP;
		}

		err = tcf_exts_validate(tp, tb, tca[TCA_RATE], &e, &flow_ext_map);

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