sock_diag: Introduce the meminfo nla core (v2)

Add a routine that dumps memory-related values of a socket.
It's made as an array to make it possible to add more stuff
here later without breaking compatibility.

Since v1: The SK_MEMINFO_ constants are in userspace
visible part of sock_diag.h, the rest is under __KERNEL__.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: xemul

include/linux/sock_diag.h

@@ -10,9 +10,22 @@ struct sock_diag_req {
 	__u8	sdiag_protocol;
 };
 
+enum {
+	SK_MEMINFO_RMEM_ALLOC,
+	SK_MEMINFO_RCVBUF,
+	SK_MEMINFO_WMEM_ALLOC,
+	SK_MEMINFO_SNDBUF,
+	SK_MEMINFO_FWD_ALLOC,
+	SK_MEMINFO_WMEM_QUEUED,
+	SK_MEMINFO_OPTMEM,
+
+	SK_MEMINFO_VARS,
+};
+
 #ifdef __KERNEL__
 struct sk_buff;
 struct nlmsghdr;
+struct sock;
 
 struct sock_diag_handler {
 	__u8 family;
@@ -28,6 +41,8 @@ void sock_diag_unregister_inet_compat(int (*fn)(struct sk_buff *skb, struct nlms
 int sock_diag_check_cookie(void *sk, __u32 *cookie);
 void sock_diag_save_cookie(void *sk, __u32 *cookie);
 
+int sock_diag_put_meminfo(struct sock *sk, struct sk_buff *skb, int attr);
+
 extern struct sock *sock_diag_nlsk;
 #endif /* KERNEL */
 #endif

net/core/sock_diag.c

@@ -4,6 +4,8 @@
 #include <net/netlink.h>
 #include <net/net_namespace.h>
 #include <linux/module.h>
+#include <linux/rtnetlink.h>
+#include <net/sock.h>
 
 #include <linux/inet_diag.h>
 #include <linux/sock_diag.h>
@@ -31,6 +33,27 @@ void sock_diag_save_cookie(void *sk, __u32 *cookie)
 }
 EXPORT_SYMBOL_GPL(sock_diag_save_cookie);
 
+int sock_diag_put_meminfo(struct sock *sk, struct sk_buff *skb, int attrtype)
+{
+	__u32 *mem;
+
+	mem = RTA_DATA(__RTA_PUT(skb, attrtype, SK_MEMINFO_VARS * sizeof(__u32)));
+
+	mem[SK_MEMINFO_RMEM_ALLOC] = sk_rmem_alloc_get(sk);
+	mem[SK_MEMINFO_RCVBUF] = sk->sk_rcvbuf;
+	mem[SK_MEMINFO_WMEM_ALLOC] = sk_wmem_alloc_get(sk);
+	mem[SK_MEMINFO_SNDBUF] = sk->sk_sndbuf;
+	mem[SK_MEMINFO_FWD_ALLOC] = sk->sk_forward_alloc;
+	mem[SK_MEMINFO_WMEM_QUEUED] = sk->sk_wmem_queued;
+	mem[SK_MEMINFO_OPTMEM] = atomic_read(&sk->sk_omem_alloc);
+
+	return 0;
+
+rtattr_failure:
+	return -EMSGSIZE;
+}
+EXPORT_SYMBOL_GPL(sock_diag_put_meminfo);
+
 void sock_diag_register_inet_compat(int (*fn)(struct sk_buff *skb, struct nlmsghdr *nlh))
 {
 	mutex_lock(&sock_diag_table_mutex);