netdev - [PATCH 5/6] net: Add variants of capable for use on netlink messages

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Message-ID: <87zjjdm5dy.fsf_-_@x220.int.ebiederm.org>
Date:	Tue, 22 Apr 2014 14:16:41 -0700
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	"David S. Miller" <davem@...emloft.net>
Cc:	Vivek Goyal <vgoyal@...hat.com>, Simo Sorce <ssorce@...hat.com>,
	"security\@kernel.org" <security@...nel.org>,
	Andy Lutomirski <luto@...capital.net>,
	<netdev@...r.kernel.org>, "Serge E. Hallyn" <serge@...lyn.com>
Subject: [PATCH 5/6] net: Add variants of capable for use on netlink messages


netlink_net_capable - The common case use, for operations that are safe on a network namespace
netlink_capable - For operations that are only known to be safe for the global root
netlink_ns_capable - The general case of capable used to handle special cases

__netlink_ns_capable - Same as netlink_ns_capable except taking a netlink_skb_parms instead of
		       the skbuff of a netlink message.

Signed-off-by: "Eric W. Biederman" <ebiederm@...ssion.com>
---
 include/linux/netlink.h  |  7 ++++++
 net/netlink/af_netlink.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 72 insertions(+)

diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index aad8eeaf416d..f64b01787ddc 100644
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -169,4 +169,11 @@ struct netlink_tap {
 extern int netlink_add_tap(struct netlink_tap *nt);
 extern int netlink_remove_tap(struct netlink_tap *nt);
 
+bool __netlink_ns_capable(const struct netlink_skb_parms *nsp,
+			  struct user_namespace *ns, int cap);
+bool netlink_ns_capable(const struct sk_buff *skb,
+			struct user_namespace *ns, int cap);
+bool netlink_capable(const struct sk_buff *skb, int cap);
+bool netlink_net_capable(const struct sk_buff *skb, int cap);
+
 #endif	/* __LINUX_NETLINK_H */
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 7f931fe4d187..81dca96d2be6 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -1360,6 +1360,71 @@ retry:
 	return err;
 }
 
+/**
+ * __netlink_ns_capable - General netlink message capability test
+ * @nsp: NETLINK_CB of the socket buffer holding a netlink command from userspace.
+ * @user_ns: The user namespace of the capability to use
+ * @cap: The capability to use
+ *
+ * Test to see if the opener of the socket we received the message
+ * from had when the netlink socket was created and the sender of the
+ * message has has the capability @cap in the user namespace @user_ns.
+ */
+bool __netlink_ns_capable(const struct netlink_skb_parms *nsp,
+			struct user_namespace *user_ns, int cap)
+{
+	return sk_ns_capable(nsp->sk, user_ns, cap);
+}
+EXPORT_SYMBOL(__netlink_ns_capable);
+
+/**
+ * netlink_ns_capable - General netlink message capability test
+ * @skb: socket buffer holding a netlink command from userspace
+ * @user_ns: The user namespace of the capability to use
+ * @cap: The capability to use
+ *
+ * Test to see if the opener of the socket we received the message
+ * from had when the netlink socket was created and the sender of the
+ * message has has the capability @cap in the user namespace @user_ns.
+ */
+bool netlink_ns_capable(const struct sk_buff *skb,
+			struct user_namespace *user_ns, int cap)
+{
+	return __netlink_ns_capable(&NETLINK_CB(skb), user_ns, cap);
+}
+EXPORT_SYMBOL(netlink_ns_capable);
+
+/**
+ * netlink_capable - Netlink global message capability test
+ * @skb: socket buffer holding a netlink command from userspace
+ * @cap: The capability to use
+ *
+ * Test to see if the opener of the socket we received the message
+ * from had when the netlink socket was created and the sender of the
+ * message has has the capability @cap in all user namespaces.
+ */
+bool netlink_capable(const struct sk_buff *skb, int cap)
+{
+	return netlink_ns_capable(skb, &init_user_ns, cap);
+}
+EXPORT_SYMBOL(netlink_capable);
+
+/**
+ * netlink_net_capable - Netlink network namespace message capability test
+ * @skb: socket buffer holding a netlink command from userspace
+ * @cap: The capability to use
+ *
+ * Test to see if the opener of the socket we received the message
+ * from had when the netlink socket was created and the sender of the
+ * message has has the capability @cap over the network namespace of
+ * the socket we received the message from.
+ */
+bool netlink_net_capable(const struct sk_buff *skb, int cap)
+{
+	return netlink_ns_capable(skb, sock_net(skb->sk)->user_ns, cap);
+}
+EXPORT_SYMBOL(netlink_net_capable);
+
 static inline int netlink_allowed(const struct socket *sock, unsigned int flag)
 {
 	return (nl_table[sock->sk->sk_protocol].flags & flag) ||
-- 
1.9.1

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