l2tp: Add debugfs files for dumping l2tp debug info

The existing pppol2tp driver exports debug info to
/proc/net/pppol2tp. Rather than adding info to that file for the new
functionality added in this patch series, we add new files in debugfs,
leaving the old /proc file for backwards compatibility (L2TPv2 only).

Currently only one file is provided: l2tp/tunnels, which lists
internal debug info for all l2tp tunnels and sessions. More files may
be added later. The info is for debug and problem analysis only -
userspace apps should use netlink to obtain status about l2tp tunnels
and sessions.

Although debugfs does not support net namespaces, the tunnels and
sessions dumped in l2tp/tunnels are only those in the net namespace of
the process reading the file.

Signed-off-by: James Chapman <jchapman@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

6 files changed, 392 insertions, 2 deletions

diff --git a/net/l2tp/Kconfig b/net/l2tp/Kconfig
index a292270c0abe..4b1e71751e10 100644
--- a/net/l2tp/Kconfig
+++ b/net/l2tp/Kconfig
@@ -31,6 +31,19 @@ menuconfig L2TP
           If you don't need L2TP, say N. To compile all L2TP code as
           modules, choose M here.
 
+config L2TP_DEBUGFS
+        tristate "L2TP debugfs support"
+        depends on L2TP && DEBUG_FS
+        help
+          Support for l2tp directory in debugfs filesystem. This may be
+          used to dump internal state of the l2tp drivers for problem
+          analysis.
+
+          If unsure, say 'Y'.
+
+          To compile this driver as a module, choose M here. The module
+          will be called l2tp_debugfs.
+
 config L2TP_V3
         bool "L2TPv3 support (EXPERIMENTAL)"
         depends on EXPERIMENTAL && L2TP
diff --git a/net/l2tp/Makefile b/net/l2tp/Makefile
index bddbf04f0ed3..110e7bc2de5e 100644
--- a/net/l2tp/Makefile
+++ b/net/l2tp/Makefile
@@ -9,3 +9,4 @@ obj-$(subst y,$(CONFIG_L2TP),$(CONFIG_PPPOL2TP)) += l2tp_ppp.o
 obj-$(subst y,$(CONFIG_L2TP),$(CONFIG_L2TP_IP)) += l2tp_ip.o
 obj-$(subst y,$(CONFIG_L2TP),$(CONFIG_L2TP_V3)) += l2tp_netlink.o
 obj-$(subst y,$(CONFIG_L2TP),$(CONFIG_L2TP_ETH)) += l2tp_eth.o
+obj-$(subst y,$(CONFIG_L2TP),$(CONFIG_L2TP_DEBUGFS)) += l2tp_debugfs.o
diff --git a/net/l2tp/l2tp_core.h b/net/l2tp/l2tp_core.h
index 2974d9ade167..571335530c6f 100644
--- a/net/l2tp/l2tp_core.h
+++ b/net/l2tp/l2tp_core.h
@@ -133,7 +133,9 @@ struct l2tp_session {
         void (*session_close)(struct l2tp_session *session);
         void (*ref)(struct l2tp_session *session);
         void (*deref)(struct l2tp_session *session);
-
+#ifdef CONFIG_L2TP_DEBUGFS
+        void (*show)(struct seq_file *m, void *priv);
+#endif
         uint8_t                 priv[0];        /* private data */
 };
 
@@ -166,7 +168,9 @@ struct l2tp_tunnel {
         struct net              *l2tp_net;      /* the net we belong to */
 
         atomic_t                ref_count;
-
+#ifdef CONFIG_DEBUG_FS
+        void (*show)(struct seq_file *m, void *arg);
+#endif
         int (*recv_payload_hook)(struct sk_buff *skb);
         void (*old_sk_destruct)(struct sock *);
         struct sock             *sock;          /* Parent socket */
diff --git a/net/l2tp/l2tp_debugfs.c b/net/l2tp/l2tp_debugfs.c
new file mode 100644
index 000000000000..908f10f9720e
--- /dev/null
+++ b/net/l2tp/l2tp_debugfs.c
@@ -0,0 +1,341 @@
+/*
+ * L2TP subsystem debugfs
+ *
+ * Copyright (c) 2010 Katalix Systems Ltd
+ *
+ *      This program is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU General Public License
+ *      as published by the Free Software Foundation; either version
+ *      2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/socket.h>
+#include <linux/hash.h>
+#include <linux/l2tp.h>
+#include <linux/in.h>
+#include <linux/etherdevice.h>
+#include <linux/spinlock.h>
+#include <linux/debugfs.h>
+#include <net/sock.h>
+#include <net/ip.h>
+#include <net/icmp.h>
+#include <net/udp.h>
+#include <net/inet_common.h>
+#include <net/inet_hashtables.h>
+#include <net/tcp_states.h>
+#include <net/protocol.h>
+#include <net/xfrm.h>
+#include <net/net_namespace.h>
+#include <net/netns/generic.h>
+
+#include "l2tp_core.h"
+
+static struct dentry *rootdir;
+static struct dentry *tunnels;
+
+struct l2tp_dfs_seq_data {
+        struct net *net;
+        int tunnel_idx;                 /* current tunnel */
+        int session_idx;                /* index of session within current tunnel */
+        struct l2tp_tunnel *tunnel;
+        struct l2tp_session *session;   /* NULL means get next tunnel */
+};
+
+static void l2tp_dfs_next_tunnel(struct l2tp_dfs_seq_data *pd)
+{
+        pd->tunnel = l2tp_tunnel_find_nth(pd->net, pd->tunnel_idx);
+        pd->tunnel_idx++;
+}
+
+static void l2tp_dfs_next_session(struct l2tp_dfs_seq_data *pd)
+{
+        pd->session = l2tp_session_find_nth(pd->tunnel, pd->session_idx);
+        pd->session_idx++;
+
+        if (pd->session == NULL) {
+                pd->session_idx = 0;
+                l2tp_dfs_next_tunnel(pd);
+        }
+
+}
+
+static void *l2tp_dfs_seq_start(struct seq_file *m, loff_t *offs)
+{
+        struct l2tp_dfs_seq_data *pd = SEQ_START_TOKEN;
+        loff_t pos = *offs;
+
+        if (!pos)
+                goto out;
+
+        BUG_ON(m->private == NULL);
+        pd = m->private;
+
+        if (pd->tunnel == NULL)
+                l2tp_dfs_next_tunnel(pd);
+        else
+                l2tp_dfs_next_session(pd);
+
+        /* NULL tunnel and session indicates end of list */
+        if ((pd->tunnel == NULL) && (pd->session == NULL))
+                pd = NULL;
+
+out:
+        return pd;
+}
+
+
+static void *l2tp_dfs_seq_next(struct seq_file *m, void *v, loff_t *pos)
+{
+        (*pos)++;
+        return NULL;
+}
+
+static void l2tp_dfs_seq_stop(struct seq_file *p, void *v)
+{
+        /* nothing to do */
+}
+
+static void l2tp_dfs_seq_tunnel_show(struct seq_file *m, void *v)
+{
+        struct l2tp_tunnel *tunnel = v;
+        int session_count = 0;
+        int hash;
+        struct hlist_node *walk;
+        struct hlist_node *tmp;
+
+        read_lock_bh(&tunnel->hlist_lock);
+        for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
+                hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) {
+                        struct l2tp_session *session;
+
+                        session = hlist_entry(walk, struct l2tp_session, hlist);
+                        if (session->session_id == 0)
+                                continue;
+
+                        session_count++;
+                }
+        }
+        read_unlock_bh(&tunnel->hlist_lock);
+
+        seq_printf(m, "\nTUNNEL %u peer %u", tunnel->tunnel_id, tunnel->peer_tunnel_id);
+        if (tunnel->sock) {
+                struct inet_sock *inet = inet_sk(tunnel->sock);
+                seq_printf(m, " from " NIPQUAD_FMT " to " NIPQUAD_FMT "\n",
+                           NIPQUAD(inet->inet_saddr), NIPQUAD(inet->inet_daddr));
+                if (tunnel->encap == L2TP_ENCAPTYPE_UDP)
+                        seq_printf(m, " source port %hu, dest port %hu\n",
+                                   ntohs(inet->inet_sport), ntohs(inet->inet_dport));
+        }
+        seq_printf(m, " L2TPv%d, %s\n", tunnel->version,
+                   tunnel->encap == L2TP_ENCAPTYPE_UDP ? "UDP" :
+                   tunnel->encap == L2TP_ENCAPTYPE_IP ? "IP" :
+                   "");
+        seq_printf(m, " %d sessions, refcnt %d/%d\n", session_count,
+                   tunnel->sock ? atomic_read(&tunnel->sock->sk_refcnt) : 0,
+                   atomic_read(&tunnel->ref_count));
+
+        seq_printf(m, " %08x rx %llu/%llu/%llu rx %llu/%llu/%llu\n",
+                   tunnel->debug,
+                   (unsigned long long)tunnel->stats.tx_packets,
+                   (unsigned long long)tunnel->stats.tx_bytes,
+                   (unsigned long long)tunnel->stats.tx_errors,
+                   (unsigned long long)tunnel->stats.rx_packets,
+                   (unsigned long long)tunnel->stats.rx_bytes,
+                   (unsigned long long)tunnel->stats.rx_errors);
+
+        if (tunnel->show != NULL)
+                tunnel->show(m, tunnel);
+}
+
+static void l2tp_dfs_seq_session_show(struct seq_file *m, void *v)
+{
+        struct l2tp_session *session = v;
+
+        seq_printf(m, "  SESSION %u, peer %u, %s\n", session->session_id,
+                   session->peer_session_id,
+                   session->pwtype == L2TP_PWTYPE_ETH ? "ETH" :
+                   session->pwtype == L2TP_PWTYPE_PPP ? "PPP" :
+                   "");
+        if (session->send_seq || session->recv_seq)
+                seq_printf(m, "   nr %hu, ns %hu\n", session->nr, session->ns);
+        seq_printf(m, "   refcnt %d\n", atomic_read(&session->ref_count));
+        seq_printf(m, "   config %d/%d/%c/%c/%s/%s %08x %u\n",
+                   session->mtu, session->mru,
+                   session->recv_seq ? 'R' : '-',
+                   session->send_seq ? 'S' : '-',
+                   session->data_seq == 1 ? "IPSEQ" :
+                   session->data_seq == 2 ? "DATASEQ" : "-",
+                   session->lns_mode ? "LNS" : "LAC",
+                   session->debug,
+                   jiffies_to_msecs(session->reorder_timeout));
+        seq_printf(m, "   offset %hu l2specific %hu/%hu\n",
+                   session->offset, session->l2specific_type, session->l2specific_len);
+        if (session->cookie_len) {
+                seq_printf(m, "   cookie %02x%02x%02x%02x",
+                           session->cookie[0], session->cookie[1],
+                           session->cookie[2], session->cookie[3]);
+                if (session->cookie_len == 8)
+                        seq_printf(m, "%02x%02x%02x%02x",
+                                   session->cookie[4], session->cookie[5],
+                                   session->cookie[6], session->cookie[7]);
+                seq_printf(m, "\n");
+        }
+        if (session->peer_cookie_len) {
+                seq_printf(m, "   peer cookie %02x%02x%02x%02x",
+                           session->peer_cookie[0], session->peer_cookie[1],
+                           session->peer_cookie[2], session->peer_cookie[3]);
+                if (session->peer_cookie_len == 8)
+                        seq_printf(m, "%02x%02x%02x%02x",
+                                   session->peer_cookie[4], session->peer_cookie[5],
+                                   session->peer_cookie[6], session->peer_cookie[7]);
+                seq_printf(m, "\n");
+        }
+
+        seq_printf(m, "   %hu/%hu tx %llu/%llu/%llu rx %llu/%llu/%llu\n",
+                   session->nr, session->ns,
+                   (unsigned long long)session->stats.tx_packets,
+                   (unsigned long long)session->stats.tx_bytes,
+                   (unsigned long long)session->stats.tx_errors,
+                   (unsigned long long)session->stats.rx_packets,
+                   (unsigned long long)session->stats.rx_bytes,
+                   (unsigned long long)session->stats.rx_errors);
+
+        if (session->show != NULL)
+                session->show(m, session);
+}
+
+static int l2tp_dfs_seq_show(struct seq_file *m, void *v)
+{
+        struct l2tp_dfs_seq_data *pd = v;
+
+        /* display header on line 1 */
+        if (v == SEQ_START_TOKEN) {
+                seq_puts(m, "TUNNEL ID, peer ID from IP to IP\n");
+                seq_puts(m, " L2TPv2/L2TPv3, UDP/IP\n");
+                seq_puts(m, " sessions session-count, refcnt refcnt/sk->refcnt\n");
+                seq_puts(m, " debug tx-pkts/bytes/errs rx-pkts/bytes/errs\n");
+                seq_puts(m, "  SESSION ID, peer ID, PWTYPE\n");
+                seq_puts(m, "   refcnt cnt\n");
+                seq_puts(m, "   offset OFFSET l2specific TYPE/LEN\n");
+                seq_puts(m, "   [ cookie ]\n");
+                seq_puts(m, "   [ peer cookie ]\n");
+                seq_puts(m, "   config mtu/mru/rcvseq/sendseq/dataseq/lns debug reorderto\n");
+                seq_puts(m, "   nr/ns tx-pkts/bytes/errs rx-pkts/bytes/errs\n");
+                goto out;
+        }
+
+        /* Show the tunnel or session context */
+        if (pd->session == NULL)
+                l2tp_dfs_seq_tunnel_show(m, pd->tunnel);
+        else
+                l2tp_dfs_seq_session_show(m, pd->session);
+
+out:
+        return 0;
+}
+
+static const struct seq_operations l2tp_dfs_seq_ops = {
+        .start          = l2tp_dfs_seq_start,
+        .next           = l2tp_dfs_seq_next,
+        .stop           = l2tp_dfs_seq_stop,
+        .show           = l2tp_dfs_seq_show,
+};
+
+static int l2tp_dfs_seq_open(struct inode *inode, struct file *file)
+{
+        struct l2tp_dfs_seq_data *pd;
+        struct seq_file *seq;
+        int rc = -ENOMEM;
+
+        pd = kzalloc(GFP_KERNEL, sizeof(*pd));
+        if (pd == NULL)
+                goto out;
+
+        /* Derive the network namespace from the pid opening the
+         * file.
+         */
+        pd->net = get_net_ns_by_pid(current->pid);
+        if (IS_ERR(pd->net)) {
+                rc = -PTR_ERR(pd->net);
+                goto err_free_pd;
+        }
+
+        rc = seq_open(file, &l2tp_dfs_seq_ops);
+        if (rc)
+                goto err_free_net;
+
+        seq = file->private_data;
+        seq->private = pd;
+
+out:
+        return rc;
+
+err_free_net:
+        put_net(pd->net);
+err_free_pd:
+        kfree(pd);
+        goto out;
+}
+
+static int l2tp_dfs_seq_release(struct inode *inode, struct file *file)
+{
+        struct l2tp_dfs_seq_data *pd;
+        struct seq_file *seq;
+
+        seq = file->private_data;
+        pd = seq->private;
+        if (pd->net)
+                put_net(pd->net);
+        kfree(pd);
+        seq_release(inode, file);
+
+        return 0;
+}
+
+static const struct file_operations l2tp_dfs_fops = {
+        .owner          = THIS_MODULE,
+        .open           = l2tp_dfs_seq_open,
+        .read           = seq_read,
+        .llseek         = seq_lseek,
+        .release        = l2tp_dfs_seq_release,
+};
+
+static int __init l2tp_debugfs_init(void)
+{
+        int rc = 0;
+
+        rootdir = debugfs_create_dir("l2tp", NULL);
+        if (IS_ERR(rootdir)) {
+                rc = PTR_ERR(rootdir);
+                rootdir = NULL;
+                goto out;
+        }
+
+        tunnels = debugfs_create_file("tunnels", 0600, rootdir, NULL, &l2tp_dfs_fops);
+        if (tunnels == NULL)
+                rc = -EIO;
+
+        printk(KERN_INFO "L2TP debugfs support\n");
+
+out:
+        if (rc)
+                printk(KERN_WARNING "l2tp debugfs: unable to init\n");
+
+        return rc;
+}
+
+static void __exit l2tp_debugfs_exit(void)
+{
+        debugfs_remove(tunnels);
+        debugfs_remove(rootdir);
+}
+
+module_init(l2tp_debugfs_init);
+module_exit(l2tp_debugfs_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
+MODULE_DESCRIPTION("L2TP debugfs driver");
+MODULE_VERSION("1.0");
diff --git a/net/l2tp/l2tp_eth.c b/net/l2tp/l2tp_eth.c
index 755c29729b6f..9848faa3d163 100644
--- a/net/l2tp/l2tp_eth.c
+++ b/net/l2tp/l2tp_eth.c
@@ -172,6 +172,17 @@ static void l2tp_eth_delete(struct l2tp_session *session)
         }
 }
 
+#ifdef CONFIG_L2TP_DEBUGFS
+static void l2tp_eth_show(struct seq_file *m, void *arg)
+{
+        struct l2tp_session *session = arg;
+        struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
+        struct net_device *dev = spriv->dev;
+
+        seq_printf(m, "   interface %s\n", dev->name);
+}
+#endif
+
 static int l2tp_eth_create(struct net *net, u32 tunnel_id, u32 session_id, u32 peer_session_id, struct l2tp_session_cfg *cfg)
 {
         struct net_device *dev;
@@ -233,6 +244,9 @@ static int l2tp_eth_create(struct net *net, u32 tunnel_id, u32 session_id, u32 p
         priv->tunnel_sock = tunnel->sock;
         session->recv_skb = l2tp_eth_dev_recv;
         session->session_close = l2tp_eth_delete;
+#ifdef CONFIG_L2TP_DEBUGFS
+        session->show = l2tp_eth_show;
+#endif
 
         spriv = l2tp_session_priv(session);
         spriv->dev = dev;
diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c
index d64f081f2b1c..1ef10e4118d2 100644
--- a/net/l2tp/l2tp_ppp.c
+++ b/net/l2tp/l2tp_ppp.c
@@ -597,6 +597,20 @@ out:
         return error;
 }
 
+#ifdef CONFIG_L2TP_DEBUGFS
+static void pppol2tp_show(struct seq_file *m, void *arg)
+{
+        struct l2tp_session *session = arg;
+        struct pppol2tp_session *ps = l2tp_session_priv(session);
+
+        if (ps) {
+                struct pppox_sock *po = pppox_sk(ps->sock);
+                if (po)
+                        seq_printf(m, "   interface %s\n", ppp_dev_name(&po->chan));
+        }
+}
+#endif
+
 /* connect() handler. Attach a PPPoX socket to a tunnel UDP socket
  */
 static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr,
@@ -734,6 +748,9 @@ static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr,
 
         session->recv_skb       = pppol2tp_recv;
         session->session_close  = pppol2tp_session_close;
+#ifdef CONFIG_L2TP_DEBUGFS
+        session->show           = pppol2tp_show;
+#endif
 
         /* We need to know each time a skb is dropped from the reorder
          * queue.