netlink: Diag core and basic socket info dumping (v2)

The netlink_diag can be built as a module, just like it's done in
unix sockets.

The core dumping message carries the basic info about netlink sockets:
family, type and protocol, portis, dst_group, dst_portid, state.

Groups can be received as an optional parameter NETLINK_DIAG_GROUPS.

Netlink sockets cab be filtered by protocols.

The socket inode number and cookie is reserved for future per-socket info
retrieving. The per-protocol filtering is also reserved for future by
requiring the sdiag_protocol to be zero.

The file /proc/net/netlink doesn't provide enough information for
dumping netlink sockets. It doesn't provide dst_group, dst_portid,
groups above 32.

v2: fix NETLINK_DIAG_MAX. Now it's equal to the last constant.

Acked-by: Pavel Emelyanov <xemul@parallels.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Pablo Neira Ayuso <pablo@netfilter.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Gao feng <gaofeng@cn.fujitsu.com>
Cc: Thomas Graf <tgraf@suug.ch>
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 188 insertions, 0 deletions

diff --git a/net/netlink/diag.c b/net/netlink/diag.c
new file mode 100644
index 000000000000..5ffb1d1cf402
--- /dev/null
+++ b/net/netlink/diag.c
@@ -0,0 +1,188 @@
+#include <linux/module.h>
+
+#include <net/sock.h>
+#include <linux/netlink.h>
+#include <linux/sock_diag.h>
+#include <linux/netlink_diag.h>
+
+#include "af_netlink.h"
+
+static int sk_diag_dump_groups(struct sock *sk, struct sk_buff *nlskb)
+{
+        struct netlink_sock *nlk = nlk_sk(sk);
+
+        if (nlk->groups == NULL)
+                return 0;
+
+        return nla_put(nlskb, NETLINK_DIAG_GROUPS, NLGRPSZ(nlk->ngroups),
+                       nlk->groups);
+}
+
+static int sk_diag_fill(struct sock *sk, struct sk_buff *skb,
+                        struct netlink_diag_req *req,
+                        u32 portid, u32 seq, u32 flags, int sk_ino)
+{
+        struct nlmsghdr *nlh;
+        struct netlink_diag_msg *rep;
+        struct netlink_sock *nlk = nlk_sk(sk);
+
+        nlh = nlmsg_put(skb, portid, seq, SOCK_DIAG_BY_FAMILY, sizeof(*rep),
+                        flags);
+        if (!nlh)
+                return -EMSGSIZE;
+
+        rep = nlmsg_data(nlh);
+        rep->ndiag_family       = AF_NETLINK;
+        rep->ndiag_type         = sk->sk_type;
+        rep->ndiag_protocol     = sk->sk_protocol;
+        rep->ndiag_state        = sk->sk_state;
+
+        rep->ndiag_ino          = sk_ino;
+        rep->ndiag_portid       = nlk->portid;
+        rep->ndiag_dst_portid   = nlk->dst_portid;
+        rep->ndiag_dst_group    = nlk->dst_group;
+        sock_diag_save_cookie(sk, rep->ndiag_cookie);
+
+        if ((req->ndiag_show & NDIAG_SHOW_GROUPS) &&
+            sk_diag_dump_groups(sk, skb))
+                goto out_nlmsg_trim;
+
+        if ((req->ndiag_show & NDIAG_SHOW_MEMINFO) &&
+            sock_diag_put_meminfo(sk, skb, NETLINK_DIAG_MEMINFO))
+                goto out_nlmsg_trim;
+
+        return nlmsg_end(skb, nlh);
+
+out_nlmsg_trim:
+        nlmsg_cancel(skb, nlh);
+        return -EMSGSIZE;
+}
+
+static int __netlink_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
+                                int protocol, int s_num)
+{
+        struct netlink_table *tbl = &nl_table[protocol];
+        struct nl_portid_hash *hash = &tbl->hash;
+        struct net *net = sock_net(skb->sk);
+        struct netlink_diag_req *req;
+        struct sock *sk;
+        int ret = 0, num = 0, i;
+
+        req = nlmsg_data(cb->nlh);
+
+        for (i = 0; i <= hash->mask; i++) {
+                sk_for_each(sk, &hash->table[i]) {
+                        if (!net_eq(sock_net(sk), net))
+                                continue;
+                        if (num < s_num) {
+                                num++;
+                                continue;
+                        }
+
+                        if (sk_diag_fill(sk, skb, req,
+                                         NETLINK_CB(cb->skb).portid,
+                                         cb->nlh->nlmsg_seq,
+                                         NLM_F_MULTI,
+                                         sock_i_ino(sk)) < 0) {
+                                ret = 1;
+                                goto done;
+                        }
+
+                        num++;
+                }
+        }
+
+        sk_for_each_bound(sk, &tbl->mc_list) {
+                if (sk_hashed(sk))
+                        continue;
+                if (!net_eq(sock_net(sk), net))
+                        continue;
+                if (num < s_num) {
+                        num++;
+                        continue;
+                }
+
+                if (sk_diag_fill(sk, skb, req,
+                                 NETLINK_CB(cb->skb).portid,
+                                 cb->nlh->nlmsg_seq,
+                                 NLM_F_MULTI,
+                                 sock_i_ino(sk)) < 0) {
+                        ret = 1;
+                        goto done;
+                }
+                num++;
+        }
+done:
+        cb->args[0] = num;
+        cb->args[1] = protocol;
+
+        return ret;
+}
+
+static int netlink_diag_dump(struct sk_buff *skb, struct netlink_callback *cb)
+{
+        struct netlink_diag_req *req;
+        int s_num = cb->args[0];
+
+        req = nlmsg_data(cb->nlh);
+
+        read_lock(&nl_table_lock);
+
+        if (req->sdiag_protocol == NDIAG_PROTO_ALL) {
+                int i;
+
+                for (i = cb->args[1]; i < MAX_LINKS; i++) {
+                        if (__netlink_diag_dump(skb, cb, i, s_num))
+                                break;
+                        s_num = 0;
+                }
+        } else {
+                if (req->sdiag_protocol >= MAX_LINKS) {
+                        read_unlock(&nl_table_lock);
+                        return -ENOENT;
+                }
+
+                __netlink_diag_dump(skb, cb, req->sdiag_protocol, s_num);
+        }
+
+        read_unlock(&nl_table_lock);
+
+        return skb->len;
+}
+
+static int netlink_diag_handler_dump(struct sk_buff *skb, struct nlmsghdr *h)
+{
+        int hdrlen = sizeof(struct netlink_diag_req);
+        struct net *net = sock_net(skb->sk);
+
+        if (nlmsg_len(h) < hdrlen)
+                return -EINVAL;
+
+        if (h->nlmsg_flags & NLM_F_DUMP) {
+                struct netlink_dump_control c = {
+                        .dump = netlink_diag_dump,
+                };
+                return netlink_dump_start(net->diag_nlsk, skb, h, &c);
+        } else
+                return -EOPNOTSUPP;
+}
+
+static const struct sock_diag_handler netlink_diag_handler = {
+        .family = AF_NETLINK,
+        .dump = netlink_diag_handler_dump,
+};
+
+static int __init netlink_diag_init(void)
+{
+        return sock_diag_register(&netlink_diag_handler);
+}
+
+static void __exit netlink_diag_exit(void)
+{
+        sock_diag_unregister(&netlink_diag_handler);
+}
+
+module_init(netlink_diag_init);
+module_exit(netlink_diag_exit);
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_NETLINK, NETLINK_SOCK_DIAG, 16 /* AF_NETLINK */);