net: add real socket cookies

A long standing problem in netlink socket dumps is the use
of kernel socket addresses as cookies.

1) It is a security concern.

2) Sockets can be reused quite quickly, so there is
   no guarantee a cookie is used once and identify
   a flow.

3) request sock, establish sock, and timewait socks
   for a given flow have different cookies.

Part of our effort to bring better TCP statistics requires
to switch to a different allocator.

In this patch, I chose to use a per network namespace 64bit generator,
and to use it only in the case a socket needs to be dumped to netlink.
(This might be refined later if needed)

Note that I tried to carry cookies from request sock, to establish sock,
then timewait sockets.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Eric Salo <salo@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 10 insertions, 2 deletions

diff --git a/include/linux/sock_diag.h b/include/linux/sock_diag.h
index b5ad7d35a636..083ac388098e 100644
--- a/include/linux/sock_diag.h
+++ b/include/linux/sock_diag.h
@@ -19,8 +19,8 @@ void sock_diag_unregister(const struct sock_diag_handler *h);
 void sock_diag_register_inet_compat(int (*fn)(struct sk_buff *skb, struct nlmsghdr *nlh));
 void sock_diag_unregister_inet_compat(int (*fn)(struct sk_buff *skb, struct nlmsghdr *nlh));
 
-int sock_diag_check_cookie(void *sk, const __u32 *cookie);
-void sock_diag_save_cookie(void *sk, __u32 *cookie);
+int sock_diag_check_cookie(struct sock *sk, const __u32 *cookie);
+void sock_diag_save_cookie(struct sock *sk, __u32 *cookie);
 
 int sock_diag_put_meminfo(struct sock *sk, struct sk_buff *skb, int attr);
 int sock_diag_put_filterinfo(bool may_report_filterinfo, struct sock *sk,
diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h
index eb16c7beed1e..e565afdc14ad 100644
--- a/include/net/inet_sock.h
+++ b/include/net/inet_sock.h
@@ -77,6 +77,8 @@ struct inet_request_sock {
 #define ir_v6_rmt_addr		req.__req_common.skc_v6_daddr
 #define ir_v6_loc_addr		req.__req_common.skc_v6_rcv_saddr
 #define ir_iif			req.__req_common.skc_bound_dev_if
+#define ir_cookie		req.__req_common.skc_cookie
+#define ireq_net		req.__req_common.skc_net
 
 	kmemcheck_bitfield_begin(flags);
 	u16			snd_wscale : 4,
diff --git a/include/net/inet_timewait_sock.h b/include/net/inet_timewait_sock.h
index 6c566034e26d..b7ce1003c429 100644
--- a/include/net/inet_timewait_sock.h
+++ b/include/net/inet_timewait_sock.h
@@ -122,6 +122,7 @@ struct inet_timewait_sock {
 #define tw_v6_rcv_saddr    	__tw_common.skc_v6_rcv_saddr
 #define tw_dport		__tw_common.skc_dport
 #define tw_num			__tw_common.skc_num
+#define tw_cookie		__tw_common.skc_cookie
 
 	int			tw_timeout;
 	volatile unsigned char	tw_substate;
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index 2cb9acb618e9..e086f4030dd2 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -56,6 +56,8 @@ struct net {
 #endif
 	spinlock_t		rules_mod_lock;
 
+	atomic64_t		cookie_gen;
+
 	struct list_head	list;		/* list of network namespaces */
 	struct list_head	cleanup_list;	/* namespaces on death row */
 	struct list_head	exit_list;	/* Use only net_mutex */
diff --git a/include/net/sock.h b/include/net/sock.h
index 250822cc1e02..d996c633bec2 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -199,6 +199,8 @@ struct sock_common {
 	struct in6_addr		skc_v6_rcv_saddr;
 #endif
 
+	atomic64_t		skc_cookie;
+
 	/*
 	 * fields between dontcopy_begin/dontcopy_end
 	 * are not copied in sock_copy()
@@ -329,6 +331,7 @@ struct sock {
 #define sk_net			__sk_common.skc_net
 #define sk_v6_daddr		__sk_common.skc_v6_daddr
 #define sk_v6_rcv_saddr	__sk_common.skc_v6_rcv_saddr
+#define sk_cookie		__sk_common.skc_cookie
 
 	socket_lock_t		sk_lock;
 	struct sk_buff_head	sk_receive_queue;