netfilter: add xt_qtaguid matching module

This module allows tracking stats at the socket level for given UIDs.
It replaces xt_owner.
If the --uid-owner is not specified, it will just count stats based on
who the skb belongs to. This will even happen on incoming skbs as it
looks into the skb via xt_socket magic to see who owns it.
If an skb is lost, it will be assigned to uid=0.

To control what sockets of what UIDs are tagged by what, one uses:
  echo t $sock_fd $accounting_tag $the_billed_uid \
     > /proc/net/xt_qtaguid/ctrl
 So whenever an skb belongs to a sock_fd, it will be accounted against
   $the_billed_uid
  and matching stats will show up under the uid with the given
   $accounting_tag.

Because the number of allocations for the stats structs is not that big:
  ~500 apps * 32 per app
we'll just do it atomic. This avoids walking lists many times, and
the fancy worker thread handling. Slabs will grow when needed later.

It use netdevice and inetaddr notifications instead of hooks in the core dev
code to track when a device comes and goes. This removes the need for
exposed iface_stat.h.

Put procfs dirs in /proc/net/xt_qtaguid/
  ctrl
  stats
  iface_stat/<iface>/...
The uid stats are obtainable in ./stats.

Change-Id: I01af4fd91c8de651668d3decb76d9bdc1e343919
Signed-off-by: JP Abgrall <jpa@google.com>

1 files changed, 2785 insertions, 0 deletions

diff --git a/net/netfilter/xt_qtaguid.c b/net/netfilter/xt_qtaguid.c
new file mode 100644
index 000000000000..08086d680c2c
--- /dev/null
+++ b/net/netfilter/xt_qtaguid.c
@@ -0,0 +1,2785 @@
+/*
+ * Kernel iptables module to track stats for packets based on user tags.
+ *
+ * (C) 2011 Google, Inc
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+/*
+ * There are run-time debug flags enabled via the debug_mask module param, or
+ * via the DEFAULT_DEBUG_MASK. See xt_qtaguid_internal.h.
+ */
+#define DEBUG
+
+#include <linux/file.h>
+#include <linux/inetdevice.h>
+#include <linux/module.h>
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter/xt_qtaguid.h>
+#include <linux/skbuff.h>
+#include <linux/workqueue.h>
+#include <net/addrconf.h>
+#include <net/sock.h>
+#include <net/tcp.h>
+#include <net/udp.h>
+
+#include <linux/netfilter/xt_socket.h>
+#include "xt_qtaguid_internal.h"
+#include "xt_qtaguid_print.h"
+
+/*
+ * We only use the xt_socket funcs within a similar context to avoid unexpected
+ * return values.
+ */
+#define XT_SOCKET_SUPPORTED_HOOKS \
+	((1 << NF_INET_PRE_ROUTING) | (1 << NF_INET_LOCAL_IN))
+
+
+static const char *module_procdirname = "xt_qtaguid";
+static struct proc_dir_entry *xt_qtaguid_procdir;
+
+static unsigned int proc_iface_perms = S_IRUGO;
+module_param_named(iface_perms, proc_iface_perms, uint, S_IRUGO | S_IWUSR);
+
+static struct proc_dir_entry *xt_qtaguid_stats_file;
+static unsigned int proc_stats_perms = S_IRUGO;
+module_param_named(stats_perms, proc_stats_perms, uint, S_IRUGO | S_IWUSR);
+
+static struct proc_dir_entry *xt_qtaguid_ctrl_file;
+#ifdef CONFIG_ANDROID_PARANOID_NETWORK
+static unsigned int proc_ctrl_perms = S_IRUGO | S_IWUGO;
+#else
+static unsigned int proc_ctrl_perms = S_IRUGO | S_IWUSR;
+#endif
+module_param_named(ctrl_perms, proc_ctrl_perms, uint, S_IRUGO | S_IWUSR);
+
+#ifdef CONFIG_ANDROID_PARANOID_NETWORK
+#include <linux/android_aid.h>
+static gid_t proc_stats_readall_gid = AID_NET_BW_STATS;
+static gid_t proc_ctrl_write_gid = AID_NET_BW_ACCT;
+#else
+/* 0 means, don't limit anybody */
+static gid_t proc_stats_readall_gid;
+static gid_t proc_ctrl_write_gid;
+#endif
+module_param_named(stats_readall_gid, proc_stats_readall_gid, uint,
+		   S_IRUGO | S_IWUSR);
+module_param_named(ctrl_write_gid, proc_ctrl_write_gid, uint,
+		   S_IRUGO | S_IWUSR);
+
+/*
+ * Limit the number of active tags (via socket tags) for a given UID.
+ * Multiple processes could share the UID.
+ */
+static int max_sock_tags = DEFAULT_MAX_SOCK_TAGS;
+module_param(max_sock_tags, int, S_IRUGO | S_IWUSR);
+
+/*
+ * After the kernel has initiallized this module, it is still possible
+ * to make it passive.
+ * Setting passive to Y:
+ *  - the iface stats handling will not act on notifications.
+ *  - iptables matches will never match.
+ *  - ctrl commands silently succeed.
+ *  - stats are always empty.
+ * This is mostly usefull when a bug is suspected.
+ */
+static bool module_passive;
+module_param_named(passive, module_passive, bool, S_IRUGO | S_IWUSR);
+
+/*
+ * Control how qtaguid data is tracked per proc/uid.
+ * Setting tag_tracking_passive to Y:
+ *  - don't create proc specific structs to track tags
+ *  - don't check that active tag stats exceed some limits.
+ *  - don't clean up socket tags on process exits.
+ * This is mostly usefull when a bug is suspected.
+ */
+static bool qtu_proc_handling_passive;
+module_param_named(tag_tracking_passive, qtu_proc_handling_passive, bool,
+		   S_IRUGO | S_IWUSR);
+
+#define QTU_DEV_NAME "xt_qtaguid"
+
+uint qtaguid_debug_mask = DEFAULT_DEBUG_MASK;
+module_param_named(debug_mask, qtaguid_debug_mask, uint, S_IRUGO | S_IWUSR);
+
+/*---------------------------------------------------------------------------*/
+static const char *iface_stat_procdirname = "iface_stat";
+static struct proc_dir_entry *iface_stat_procdir;
+static const char *iface_stat_all_procfilename = "iface_stat_all";
+static struct proc_dir_entry *iface_stat_all_procfile;
+
+/*
+ * Ordering of locks:
+ *  outer locks:
+ *    iface_stat_list_lock
+ *    sock_tag_list_lock
+ *  inner locks:
+ *    uid_tag_data_tree_lock
+ *    tag_counter_set_list_lock
+ * Notice how sock_tag_list_lock is held sometimes when uid_tag_data_tree_lock
+ * is acquired.
+ *
+ * Call tree with all lock holders as of 2011-09-25:
+ *
+ * iface_stat_all_proc_read()
+ *   iface_stat_list_lock
+ *     (struct iface_stat)
+ *
+ * qtaguid_ctrl_proc_read()
+ *   sock_tag_list_lock
+ *     (sock_tag_tree)
+ *     (struct proc_qtu_data->sock_tag_list)
+ *   prdebug_full_state()
+ *     sock_tag_list_lock
+ *       (sock_tag_tree)
+ *     uid_tag_data_tree_lock
+ *       (uid_tag_data_tree)
+ *       (proc_qtu_data_tree)
+ *     iface_stat_list_lock
+ *
+ * qtaguid_stats_proc_read()
+ *   iface_stat_list_lock
+ *     struct iface_stat->tag_stat_list_lock
+ *
+ * qtudev_open()
+ *   uid_tag_data_tree_lock
+ *
+ * qtudev_release()
+ *   sock_tag_data_list_lock
+ *     uid_tag_data_tree_lock
+ *   prdebug_full_state()
+ *     sock_tag_list_lock
+ *     uid_tag_data_tree_lock
+ *     iface_stat_list_lock
+ *
+ * iface_netdev_event_handler()
+ *   iface_stat_create()
+ *     iface_stat_list_lock
+ *   iface_stat_update()
+ *     iface_stat_list_lock
+ *
+ * iface_inetaddr_event_handler()
+ *   iface_stat_create()
+ *     iface_stat_list_lock
+ *   iface_stat_update()
+ *     iface_stat_list_lock
+ *
+ * iface_inet6addr_event_handler()
+ *   iface_stat_create_ipv6()
+ *     iface_stat_list_lock
+ *   iface_stat_update()
+ *     iface_stat_list_lock
+ *
+ * qtaguid_mt()
+ *   account_for_uid()
+ *     if_tag_stat_update()
+ *       get_sock_stat()
+ *         sock_tag_list_lock
+ *       struct iface_stat->tag_stat_list_lock
+ *         tag_stat_update()
+ *           get_active_counter_set()
+ *             tag_counter_set_list_lock
+ *         tag_stat_update()
+ *           get_active_counter_set()
+ *             tag_counter_set_list_lock
+ *
+ *
+ * qtaguid_ctrl_parse()
+ *   ctrl_cmd_delete()
+ *     sock_tag_list_lock
+ *     tag_counter_set_list_lock
+ *     iface_stat_list_lock
+ *       struct iface_stat->tag_stat_list_lock
+ *     uid_tag_data_tree_lock
+ *   ctrl_cmd_counter_set()
+ *     tag_counter_set_list_lock
+ *   ctrl_cmd_tag()
+ *     sock_tag_list_lock
+ *       (sock_tag_tree)
+ *       get_tag_ref()
+ *         uid_tag_data_tree_lock
+ *           (uid_tag_data_tree)
+ *       uid_tag_data_tree_lock
+ *         (proc_qtu_data_tree)
+ *   ctrl_cmd_untag()
+ *     sock_tag_list_lock
+ *     uid_tag_data_tree_lock
+ *
+ */
+static LIST_HEAD(iface_stat_list);
+static DEFINE_SPINLOCK(iface_stat_list_lock);
+
+static struct rb_root sock_tag_tree = RB_ROOT;
+static DEFINE_SPINLOCK(sock_tag_list_lock);
+
+static struct rb_root tag_counter_set_tree = RB_ROOT;
+static DEFINE_SPINLOCK(tag_counter_set_list_lock);
+
+static struct rb_root uid_tag_data_tree = RB_ROOT;
+static DEFINE_SPINLOCK(uid_tag_data_tree_lock);
+
+static struct rb_root proc_qtu_data_tree = RB_ROOT;
+/* No proc_qtu_data_tree_lock; use uid_tag_data_tree_lock */
+
+static struct qtaguid_event_counts qtu_events;
+/*----------------------------------------------*/
+static bool can_manipulate_uids(void)
+{
+	/* root pwnd */
+	return unlikely(!current_fsuid()) || unlikely(!proc_ctrl_write_gid)
+		|| in_egroup_p(proc_ctrl_write_gid);
+}
+
+static bool can_impersonate_uid(uid_t uid)
+{
+	return uid == current_fsuid() || can_manipulate_uids();
+}
+
+static bool can_read_other_uid_stats(uid_t uid)
+{
+	/* root pwnd */
+	return unlikely(!current_fsuid()) || uid == current_fsuid()
+		|| unlikely(!proc_stats_readall_gid)
+		|| in_egroup_p(proc_stats_readall_gid);
+}
+
+static inline void dc_add_byte_packets(struct data_counters *counters, int set,
+				  enum ifs_tx_rx direction,
+				  enum ifs_proto ifs_proto,
+				  int bytes,
+				  int packets)
+{
+	counters->bpc[set][direction][ifs_proto].bytes += bytes;
+	counters->bpc[set][direction][ifs_proto].packets += packets;
+}
+
+static inline uint64_t dc_sum_bytes(struct data_counters *counters,
+				    int set,
+				    enum ifs_tx_rx direction)
+{
+	return counters->bpc[set][direction][IFS_TCP].bytes
+		+ counters->bpc[set][direction][IFS_UDP].bytes
+		+ counters->bpc[set][direction][IFS_PROTO_OTHER].bytes;
+}
+
+static inline uint64_t dc_sum_packets(struct data_counters *counters,
+				      int set,
+				      enum ifs_tx_rx direction)
+{
+	return counters->bpc[set][direction][IFS_TCP].packets
+		+ counters->bpc[set][direction][IFS_UDP].packets
+		+ counters->bpc[set][direction][IFS_PROTO_OTHER].packets;
+}
+
+static struct tag_node *tag_node_tree_search(struct rb_root *root, tag_t tag)
+{
+	struct rb_node *node = root->rb_node;
+
+	while (node) {
+		struct tag_node *data = rb_entry(node, struct tag_node, node);
+		int result;
+		RB_DEBUG("qtaguid: tag_node_tree_search(0x%llx): "
+			 " node=%p data=%p\n", tag, node, data);
+		result = tag_compare(tag, data->tag);
+		RB_DEBUG("qtaguid: tag_node_tree_search(0x%llx): "
+			 " data.tag=0x%llx (uid=%u) res=%d\n",
+			 tag, data->tag, get_uid_from_tag(data->tag), result);
+		if (result < 0)
+			node = node->rb_left;
+		else if (result > 0)
+			node = node->rb_right;
+		else
+			return data;
+	}
+	return NULL;
+}
+
+static void tag_node_tree_insert(struct tag_node *data, struct rb_root *root)
+{
+	struct rb_node **new = &(root->rb_node), *parent = NULL;
+
+	/* Figure out where to put new node */
+	while (*new) {
+		struct tag_node *this = rb_entry(*new, struct tag_node,
+						 node);
+		int result = tag_compare(data->tag, this->tag);
+		RB_DEBUG("qtaguid: %s(): tag=0x%llx"
+			 " (uid=%u)\n", __func__,
+			 this->tag,
+			 get_uid_from_tag(this->tag));
+		parent = *new;
+		if (result < 0)
+			new = &((*new)->rb_left);
+		else if (result > 0)
+			new = &((*new)->rb_right);
+		else
+			BUG();
+	}
+
+	/* Add new node and rebalance tree. */
+	rb_link_node(&data->node, parent, new);
+	rb_insert_color(&data->node, root);
+}
+
+static void tag_stat_tree_insert(struct tag_stat *data, struct rb_root *root)
+{
+	tag_node_tree_insert(&data->tn, root);
+}
+
+static struct tag_stat *tag_stat_tree_search(struct rb_root *root, tag_t tag)
+{
+	struct tag_node *node = tag_node_tree_search(root, tag);
+	if (!node)
+		return NULL;
+	return rb_entry(&node->node, struct tag_stat, tn.node);
+}
+
+static void tag_counter_set_tree_insert(struct tag_counter_set *data,
+					struct rb_root *root)
+{
+	tag_node_tree_insert(&data->tn, root);
+}
+
+static struct tag_counter_set *tag_counter_set_tree_search(struct rb_root *root,
+							   tag_t tag)
+{
+	struct tag_node *node = tag_node_tree_search(root, tag);
+	if (!node)
+		return NULL;
+	return rb_entry(&node->node, struct tag_counter_set, tn.node);
+
+}
+
+static void tag_ref_tree_insert(struct tag_ref *data, struct rb_root *root)
+{
+	tag_node_tree_insert(&data->tn, root);
+}
+
+static struct tag_ref *tag_ref_tree_search(struct rb_root *root, tag_t tag)
+{
+	struct tag_node *node = tag_node_tree_search(root, tag);
+	if (!node)
+		return NULL;
+	return rb_entry(&node->node, struct tag_ref, tn.node);
+}
+
+static struct sock_tag *sock_tag_tree_search(struct rb_root *root,
+					     const struct sock *sk)
+{
+	struct rb_node *node = root->rb_node;
+
+	while (node) {
+		struct sock_tag *data = rb_entry(node, struct sock_tag,
+						 sock_node);
+		if (sk < data->sk)
+			node = node->rb_left;
+		else if (sk > data->sk)
+			node = node->rb_right;
+		else
+			return data;
+	}
+	return NULL;
+}
+
+static void sock_tag_tree_insert(struct sock_tag *data, struct rb_root *root)
+{
+	struct rb_node **new = &(root->rb_node), *parent = NULL;
+
+	/* Figure out where to put new node */
+	while (*new) {
+		struct sock_tag *this = rb_entry(*new, struct sock_tag,
+						 sock_node);
+		parent = *new;
+		if (data->sk < this->sk)
+			new = &((*new)->rb_left);
+		else if (data->sk > this->sk)
+			new = &((*new)->rb_right);
+		else
+			BUG();
+	}
+
+	/* Add new node and rebalance tree. */
+	rb_link_node(&data->sock_node, parent, new);
+	rb_insert_color(&data->sock_node, root);
+}
+
+static void sock_tag_tree_erase(struct rb_root *st_to_free_tree)
+{
+	struct rb_node *node;
+	struct sock_tag *st_entry;
+
+	node = rb_first(st_to_free_tree);
+	while (node) {
+		st_entry = rb_entry(node, struct sock_tag, sock_node);
+		node = rb_next(node);
+		CT_DEBUG("qtaguid: %s(): "
+			 "erase st: sk=%p tag=0x%llx (uid=%u)\n", __func__,
+			 st_entry->sk,
+			 st_entry->tag,
+			 get_uid_from_tag(st_entry->tag));
+		rb_erase(&st_entry->sock_node, st_to_free_tree);
+		sockfd_put(st_entry->socket);
+		kfree(st_entry);
+	}
+}
+
+static struct proc_qtu_data *proc_qtu_data_tree_search(struct rb_root *root,
+						       const pid_t pid)
+{
+	struct rb_node *node = root->rb_node;
+
+	while (node) {
+		struct proc_qtu_data *data = rb_entry(node,
+						      struct proc_qtu_data,
+						      node);
+		if (pid < data->pid)
+			node = node->rb_left;
+		else if (pid > data->pid)
+			node = node->rb_right;
+		else
+			return data;
+	}
+	return NULL;
+}
+
+static void proc_qtu_data_tree_insert(struct proc_qtu_data *data,
+				      struct rb_root *root)
+{
+	struct rb_node **new = &(root->rb_node), *parent = NULL;
+
+	/* Figure out where to put new node */
+	while (*new) {
+		struct proc_qtu_data *this = rb_entry(*new,
+						      struct proc_qtu_data,
+						      node);
+		parent = *new;
+		if (data->pid < this->pid)
+			new = &((*new)->rb_left);
+		else if (data->pid > this->pid)
+			new = &((*new)->rb_right);
+		else
+			BUG();
+	}
+
+	/* Add new node and rebalance tree. */
+	rb_link_node(&data->node, parent, new);
+	rb_insert_color(&data->node, root);
+}
+
+static void uid_tag_data_tree_insert(struct uid_tag_data *data,
+				     struct rb_root *root)
+{
+	struct rb_node **new = &(root->rb_node), *parent = NULL;
+
+	/* Figure out where to put new node */
+	while (*new) {
+		struct uid_tag_data *this = rb_entry(*new,
+						     struct uid_tag_data,
+						     node);
+		parent = *new;
+		if (data->uid < this->uid)
+			new = &((*new)->rb_left);
+		else if (data->uid > this->uid)
+			new = &((*new)->rb_right);
+		else
+			BUG();
+	}
+
+	/* Add new node and rebalance tree. */
+	rb_link_node(&data->node, parent, new);
+	rb_insert_color(&data->node, root);
+}
+
+static struct uid_tag_data *uid_tag_data_tree_search(struct rb_root *root,
+						     uid_t uid)
+{
+	struct rb_node *node = root->rb_node;
+
+	while (node) {
+		struct uid_tag_data *data = rb_entry(node,
+						     struct uid_tag_data,
+						     node);
+		if (uid < data->uid)
+			node = node->rb_left;
+		else if (uid > data->uid)
+			node = node->rb_right;
+		else
+			return data;
+	}
+	return NULL;
+}
+
+/*
+ * Allocates a new uid_tag_data struct if needed.
+ * Returns a pointer to the found or allocated uid_tag_data.
+ * Returns a PTR_ERR on failures, and lock is not held.
+ * If found is not NULL:
+ *   sets *found to true if not allocated.
+ *   sets *found to false if allocated.
+ */
+struct uid_tag_data *get_uid_data(uid_t uid, bool *found_res)
+{
+	struct uid_tag_data *utd_entry;
+
+	/* Look for top level uid_tag_data for the UID */
+	utd_entry = uid_tag_data_tree_search(&uid_tag_data_tree, uid);
+	DR_DEBUG("qtaguid: get_uid_data(%u) utd=%p\n", uid, utd_entry);
+
+	if (found_res)
+		*found_res = utd_entry;
+	if (utd_entry)
+		return utd_entry;
+
+	utd_entry = kzalloc(sizeof(*utd_entry), GFP_ATOMIC);
+	if (!utd_entry) {
+		pr_err("qtaguid: get_uid_data(%u): "
+		       "tag data alloc failed\n", uid);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	utd_entry->uid = uid;
+	utd_entry->tag_ref_tree = RB_ROOT;
+	uid_tag_data_tree_insert(utd_entry, &uid_tag_data_tree);
+	DR_DEBUG("qtaguid: get_uid_data(%u) new utd=%p\n", uid, utd_entry);
+	return utd_entry;
+}
+
+/* Never returns NULL. Either PTR_ERR or a valid ptr. */
+static struct tag_ref *new_tag_ref(tag_t new_tag,
+				   struct uid_tag_data *utd_entry)
+{
+	struct tag_ref *tr_entry;
+	int res;
+
+	if (utd_entry->num_active_tags + 1 > max_sock_tags) {
+		pr_info("qtaguid: new_tag_ref(0x%llx): "
+			"tag ref alloc quota exceeded. max=%d\n",
+			new_tag, max_sock_tags);
+		res = -EMFILE;
+		goto err_res;
+
+	}
+
+	tr_entry = kzalloc(sizeof(*tr_entry), GFP_ATOMIC);
+	if (!tr_entry) {
+		pr_err("qtaguid: new_tag_ref(0x%llx): "
+		       "tag ref alloc failed\n",
+		       new_tag);
+		res = -ENOMEM;
+		goto err_res;
+	}
+	tr_entry->tn.tag = new_tag;
+	/* tr_entry->num_sock_tags  handled by caller */
+	utd_entry->num_active_tags++;
+	tag_ref_tree_insert(tr_entry, &utd_entry->tag_ref_tree);
+	DR_DEBUG("qtaguid: new_tag_ref(0x%llx): "
+		 " inserted new tag ref %p\n",
+		 new_tag, tr_entry);
+	return tr_entry;
+
+err_res:
+	return ERR_PTR(res);
+}
+
+static struct tag_ref *lookup_tag_ref(tag_t full_tag,
+				      struct uid_tag_data **utd_res)
+{
+	struct uid_tag_data *utd_entry;
+	struct tag_ref *tr_entry;
+	bool found_utd;
+	uid_t uid = get_uid_from_tag(full_tag);
+
+	DR_DEBUG("qtaguid: lookup_tag_ref(tag=0x%llx (uid=%u))\n",
+		 full_tag, uid);
+
+	utd_entry = get_uid_data(uid, &found_utd);
+	if (IS_ERR_OR_NULL(utd_entry)) {
+		if (utd_res)
+			*utd_res = utd_entry;
+		return NULL;
+	}
+
+	tr_entry = tag_ref_tree_search(&utd_entry->tag_ref_tree, full_tag);
+	if (utd_res)
+		*utd_res = utd_entry;
+	DR_DEBUG("qtaguid: lookup_tag_ref(0x%llx) utd_entry=%p tr_entry=%p\n",
+		 full_tag, utd_entry, tr_entry);
+	return tr_entry;
+}
+
+/* Never returns NULL. Either PTR_ERR or a valid ptr. */
+static struct tag_ref *get_tag_ref(tag_t full_tag,
+				   struct uid_tag_data **utd_res)
+{
+	struct uid_tag_data *utd_entry;
+	struct tag_ref *tr_entry;
+
+	DR_DEBUG("qtaguid: get_tag_ref(0x%llx)\n",
+		 full_tag);
+	spin_lock_bh(&uid_tag_data_tree_lock);
+	tr_entry = lookup_tag_ref(full_tag, &utd_entry);
+	BUG_ON(IS_ERR_OR_NULL(utd_entry));
+	if (!tr_entry)
+		tr_entry = new_tag_ref(full_tag, utd_entry);
+
+	spin_unlock_bh(&uid_tag_data_tree_lock);
+	if (utd_res)
+		*utd_res = utd_entry;
+	DR_DEBUG("qtaguid: get_tag_ref(0x%llx) utd=%p tr=%p\n",
+		 full_tag, utd_entry, tr_entry);
+	return tr_entry;
+}
+
+/* Checks and maybe frees the UID Tag Data entry */
+static void put_utd_entry(struct uid_tag_data *utd_entry)
+{
+	/* Are we done with the UID tag data entry? */
+	if (RB_EMPTY_ROOT(&utd_entry->tag_ref_tree) &&
+		!utd_entry->num_pqd) {
+		DR_DEBUG("qtaguid: %s(): "
+			 "erase utd_entry=%p uid=%u "
+			 "by pid=%u tgid=%u uid=%u\n", __func__,
+			 utd_entry, utd_entry->uid,
+			 current->pid, current->tgid, current_fsuid());
+		BUG_ON(utd_entry->num_active_tags);
+		rb_erase(&utd_entry->node, &uid_tag_data_tree);
+		kfree(utd_entry);
+	} else {
+		DR_DEBUG("qtaguid: %s(): "
+			 "utd_entry=%p still has %d tags %d proc_qtu_data\n",
+			 __func__, utd_entry, utd_entry->num_active_tags,
+			 utd_entry->num_pqd);
+		BUG_ON(!(utd_entry->num_active_tags ||
+			 utd_entry->num_pqd));
+	}
+}
+
+/*
+ * If no sock_tags are using this tag_ref,
+ * decrements refcount of utd_entry, removes tr_entry
+ * from utd_entry->tag_ref_tree and frees.
+ */
+static void free_tag_ref_from_utd_entry(struct tag_ref *tr_entry,
+					struct uid_tag_data *utd_entry)
+{
+	DR_DEBUG("qtaguid: %s(): %p tag=0x%llx (uid=%u)\n", __func__,
+		 tr_entry, tr_entry->tn.tag,
+		 get_uid_from_tag(tr_entry->tn.tag));
+	if (!tr_entry->num_sock_tags) {
+		BUG_ON(!utd_entry->num_active_tags);
+		utd_entry->num_active_tags--;
+		rb_erase(&tr_entry->tn.node, &utd_entry->tag_ref_tree);
+		DR_DEBUG("qtaguid: %s(): erased %p\n", __func__, tr_entry);
+		kfree(tr_entry);
+	}
+}
+
+static void put_tag_ref_tree(tag_t full_tag, struct uid_tag_data *utd_entry)
+{
+	struct rb_node *node;
+	struct tag_ref *tr_entry;
+	tag_t acct_tag;
+
+	DR_DEBUG("qtaguid: %s(tag=0x%llx (uid=%u))\n", __func__,
+		 full_tag, get_uid_from_tag(full_tag));
+	acct_tag = get_atag_from_tag(full_tag);
+	node = rb_first(&utd_entry->tag_ref_tree);
+	while (node) {
+		tr_entry = rb_entry(node, struct tag_ref, tn.node);
+		node = rb_next(node);
+		if (!acct_tag || tr_entry->tn.tag == full_tag)
+			free_tag_ref_from_utd_entry(tr_entry, utd_entry);
+	}
+}
+
+static int read_proc_u64(char *page, char **start, off_t off,
+			int count, int *eof, void *data)
+{
+	int len;
+	uint64_t value;
+	char *p = page;
+	uint64_t *iface_entry = data;
+
+	if (!data)
+		return 0;
+
+	value = *iface_entry;
+	p += sprintf(p, "%llu\n", value);
+	len = (p - page) - off;
+	*eof = (len <= count) ? 1 : 0;
+	*start = page + off;
+	return len;
+}
+
+static int read_proc_bool(char *page, char **start, off_t off,
+			int count, int *eof, void *data)
+{
+	int len;
+	bool value;
+	char *p = page;
+	bool *bool_entry = data;
+
+	if (!data)
+		return 0;
+
+	value = *bool_entry;
+	p += sprintf(p, "%u\n", value);
+	len = (p - page) - off;
+	*eof = (len <= count) ? 1 : 0;
+	*start = page + off;
+	return len;
+}
+
+static int get_active_counter_set(tag_t tag)
+{
+	int active_set = 0;
+	struct tag_counter_set *tcs;
+
+	MT_DEBUG("qtaguid: get_active_counter_set(tag=0x%llx)"
+		 " (uid=%u)\n",
+		 tag, get_uid_from_tag(tag));
+	/* For now we only handle UID tags for active sets */
+	tag = get_utag_from_tag(tag);
+	spin_lock_bh(&tag_counter_set_list_lock);
+	tcs = tag_counter_set_tree_search(&tag_counter_set_tree, tag);
+	if (tcs)
+		active_set = tcs->active_set;
+	spin_unlock_bh(&tag_counter_set_list_lock);
+	return active_set;
+}
+
+/*
+ * Find the entry for tracking the specified interface.
+ * Caller must hold iface_stat_list_lock
+ */
+static struct iface_stat *get_iface_entry(const char *ifname)
+{
+	struct iface_stat *iface_entry;
+
+	/* Find the entry for tracking the specified tag within the interface */
+	if (ifname == NULL) {
+		pr_info("qtaguid: iface_stat: get() NULL device name\n");
+		return NULL;
+	}
+
+	/* Iterate over interfaces */
+	list_for_each_entry(iface_entry, &iface_stat_list, list) {
+		if (!strcmp(ifname, iface_entry->ifname))
+			goto done;
+	}
+	iface_entry = NULL;
+done:
+	return iface_entry;
+}
+
+static int iface_stat_all_proc_read(char *page, char **num_items_returned,
+				    off_t items_to_skip, int char_count,
+				    int *eof, void *data)
+{
+	char *outp = page;
+	int item_index = 0;
+	int len;
+	struct iface_stat *iface_entry;
+	struct rtnl_link_stats64 dev_stats, *stats;
+	struct rtnl_link_stats64 no_dev_stats = {0};
+
+	if (unlikely(module_passive)) {
+		*eof = 1;
+		return 0;
+	}
+
+	CT_DEBUG("qtaguid:proc iface_stat_all "
+		 "page=%p *num_items_returned=%p off=%ld "
+		 "char_count=%d *eof=%d\n", page, *num_items_returned,
+		 items_to_skip, char_count, *eof);
+
+	if (*eof)
+		return 0;
+
+	/*
+	 * This lock will prevent iface_stat_update() from changing active,
+	 * and in turn prevent an interface from unregistering itself.
+	 */
+	spin_lock_bh(&iface_stat_list_lock);
+	list_for_each_entry(iface_entry, &iface_stat_list, list) {
+		if (item_index++ < items_to_skip)
+			continue;
+
+		if (iface_entry->active) {
+			stats = dev_get_stats(iface_entry->net_dev,
+					      &dev_stats);
+		} else {
+			stats = &no_dev_stats;
+		}
+		len = snprintf(outp, char_count,
+			       "%s %d "
+			       "%llu %llu %llu %llu "
+			       "%llu %llu %llu %llu\n",
+			       iface_entry->ifname,
+			       iface_entry->active,
+			       iface_entry->totals[IFS_RX].bytes,
+			       iface_entry->totals[IFS_RX].packets,
+			       iface_entry->totals[IFS_TX].bytes,
+			       iface_entry->totals[IFS_TX].packets,
+			       stats->rx_bytes, stats->rx_packets,
+			       stats->tx_bytes, stats->tx_packets);
+		if (len >= char_count) {
+			spin_unlock_bh(&iface_stat_list_lock);
+			*outp = '\0';
+			return outp - page;
+		}
+		outp += len;
+		char_count -= len;
+		(*num_items_returned)++;
+	}
+	spin_unlock_bh(&iface_stat_list_lock);
+
+	*eof = 1;
+	return outp - page;
+}
+
+static void iface_create_proc_worker(struct work_struct *work)
+{
+	struct proc_dir_entry *proc_entry;
+	struct iface_stat_work *isw = container_of(work, struct iface_stat_work,
+						   iface_work);
+	struct iface_stat *new_iface  = isw->iface_entry;
+
+	/* iface_entries are not deleted, so safe to manipulate. */
+	proc_entry = proc_mkdir(new_iface->ifname, iface_stat_procdir);
+	if (IS_ERR_OR_NULL(proc_entry)) {
+		pr_err("qtaguid: iface_stat: create_proc(): alloc failed.\n");
+		kfree(isw);
+		return;
+	}
+
+	new_iface->proc_ptr = proc_entry;
+
+	create_proc_read_entry("tx_bytes", proc_iface_perms, proc_entry,
+			read_proc_u64, &new_iface->totals[IFS_TX].bytes);
+	create_proc_read_entry("rx_bytes", proc_iface_perms, proc_entry,
+			read_proc_u64, &new_iface->totals[IFS_RX].bytes);
+	create_proc_read_entry("tx_packets", proc_iface_perms, proc_entry,
+			read_proc_u64, &new_iface->totals[IFS_TX].packets);
+	create_proc_read_entry("rx_packets", proc_iface_perms, proc_entry,
+			read_proc_u64, &new_iface->totals[IFS_RX].packets);
+	create_proc_read_entry("active", proc_iface_perms, proc_entry,
+			read_proc_bool, &new_iface->active);
+
+	IF_DEBUG("qtaguid: iface_stat: create_proc(): done "
+		 "entry=%p dev=%s\n", new_iface, new_iface->ifname);
+	kfree(isw);
+}
+
+/*
+ * Will set the entry's active state, and
+ * update the net_dev accordingly also.
+ */
+static void _iface_stat_set_active(struct iface_stat *entry,
+				   struct net_device *net_dev,
+				   bool activate)
+{
+	if (activate) {
+		entry->net_dev = net_dev;
+		entry->active = true;
+		IF_DEBUG("qtaguid: %s(%s): "
+			 "enable tracking. rfcnt=%d\n", __func__,
+			 entry->ifname,
+			 percpu_read(*net_dev->pcpu_refcnt));
+	} else {
+		entry->active = false;
+		entry->net_dev = NULL;
+		IF_DEBUG("qtaguid: %s(%s): "
+			 "disable tracking. rfcnt=%d\n", __func__,
+			 entry->ifname,
+			 percpu_read(*net_dev->pcpu_refcnt));
+
+	}
+}
+
+/* Caller must hold iface_stat_list_lock */
+static struct iface_stat *iface_alloc(struct net_device *net_dev)
+{
+	struct iface_stat *new_iface;
+	struct iface_stat_work *isw;
+
+	new_iface = kzalloc(sizeof(*new_iface), GFP_ATOMIC);
+	if (new_iface == NULL) {
+		pr_err("qtaguid: iface_stat: create(%s): "
+		       "iface_stat alloc failed\n", net_dev->name);
+		return NULL;
+	}
+	new_iface->ifname = kstrdup(net_dev->name, GFP_ATOMIC);
+	if (new_iface->ifname == NULL) {
+		pr_err("qtaguid: iface_stat: create(%s): "
+		       "ifname alloc failed\n", net_dev->name);
+		kfree(new_iface);
+		return NULL;
+	}
+	spin_lock_init(&new_iface->tag_stat_list_lock);
+	new_iface->tag_stat_tree = RB_ROOT;
+	_iface_stat_set_active(new_iface, net_dev, true);
+
+	/*
+	 * ipv6 notifier chains are atomic :(
+	 * No create_proc_read_entry() for you!
+	 */
+	isw = kmalloc(sizeof(*isw), GFP_ATOMIC);
+	if (!isw) {
+		pr_err("qtaguid: iface_stat: create(%s): "
+		       "work alloc failed\n", new_iface->ifname);
+		_iface_stat_set_active(new_iface, net_dev, false);
+		kfree(new_iface->ifname);
+		kfree(new_iface);
+		return NULL;
+	}
+	isw->iface_entry = new_iface;
+	INIT_WORK(&isw->iface_work, iface_create_proc_worker);
+	schedule_work(&isw->iface_work);
+	list_add(&new_iface->list, &iface_stat_list);
+	return new_iface;
+}
+
+static void iface_check_stats_reset_and_adjust(struct net_device *net_dev,
+					       struct iface_stat *iface)
+{
+	struct rtnl_link_stats64 dev_stats, *stats;
+	bool stats_rewound;
+
+	stats = dev_get_stats(net_dev, &dev_stats);
+	/* No empty packets */
+	stats_rewound =
+		(stats->rx_bytes < iface->last_known[IFS_RX].bytes)
+		|| (stats->tx_bytes < iface->last_known[IFS_TX].bytes);
+
+	IF_DEBUG("qtaguid: %s(%s): iface=%p netdev=%p "
+		 "bytes rx/tx=%llu/%llu "
+		 "active=%d last_known=%d "
+		 "stats_rewound=%d\n", __func__,
+		 net_dev ? net_dev->name : "?",
+		 iface, net_dev,
+		 stats->rx_bytes, stats->tx_bytes,
+		 iface->active, iface->last_known_valid, stats_rewound);
+
+	if (iface->active && iface->last_known_valid && stats_rewound) {
+		pr_warn_once("qtaguid: iface_stat: %s(%s): "
+			     "iface reset its stats unexpectedly\n", __func__,
+			     net_dev->name);
+
+		iface->totals[IFS_TX].bytes += iface->last_known[IFS_TX].bytes;
+		iface->totals[IFS_TX].packets +=
+			iface->last_known[IFS_TX].packets;
+		iface->totals[IFS_RX].bytes += iface->last_known[IFS_RX].bytes;
+		iface->totals[IFS_RX].packets +=
+			iface->last_known[IFS_RX].packets;
+		iface->last_known_valid = false;
+		IF_DEBUG("qtaguid: %s(%s): iface=%p "
+			 "used last known bytes rx/tx=%llu/%llu\n", __func__,
+			 iface->ifname, iface, iface->last_known[IFS_RX].bytes,
+			 iface->last_known[IFS_TX].bytes);
+	}
+}
+
+/*
+ * Create a new entry for tracking the specified interface.
+ * Do nothing if the entry already exists.
+ * Called when an interface is configured with a valid IP address.
+ */
+static void iface_stat_create(struct net_device *net_dev,
+			      struct in_ifaddr *ifa)
+{
+	struct in_device *in_dev = NULL;
+	const char *ifname;
+	struct iface_stat *entry;
+	__be32 ipaddr = 0;
+	struct iface_stat *new_iface;
+
+	IF_DEBUG("qtaguid: iface_stat: create(%s): ifa=%p netdev=%p\n",
+		 net_dev ? net_dev->name : "?",
+		 ifa, net_dev);
+	if (!net_dev) {
+		pr_err("qtaguid: iface_stat: create(): no net dev\n");
+		return;
+	}
+
+	ifname = net_dev->name;
+	if (!ifa) {
+		in_dev = in_dev_get(net_dev);
+		if (!in_dev) {
+			pr_err("qtaguid: iface_stat: create(%s): no inet dev\n",
+			       ifname);
+			return;
+		}
+		IF_DEBUG("qtaguid: iface_stat: create(%s): in_dev=%p\n",
+			 ifname, in_dev);
+		for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next) {
+			IF_DEBUG("qtaguid: iface_stat: create(%s): "
+				 "ifa=%p ifa_label=%s\n",
+				 ifname, ifa,
+				 ifa->ifa_label ? ifa->ifa_label : "(null)");
+			if (ifa->ifa_label && !strcmp(ifname, ifa->ifa_label))
+				break;
+		}
+	}
+
+	if (!ifa) {
+		IF_DEBUG("qtaguid: iface_stat: create(%s): no matching IP\n",
+			 ifname);
+		goto done_put;
+	}
+	ipaddr = ifa->ifa_local;
+
+	spin_lock_bh(&iface_stat_list_lock);
+	entry = get_iface_entry(ifname);
+	if (entry != NULL) {
+		bool activate = !ipv4_is_loopback(ipaddr);
+		IF_DEBUG("qtaguid: iface_stat: create(%s): entry=%p\n",
+			 ifname, entry);
+		iface_check_stats_reset_and_adjust(net_dev, entry);
+		_iface_stat_set_active(entry, net_dev, activate);
+		IF_DEBUG("qtaguid: %s(%s): "
+			 "tracking now %d on ip=%pI4\n", __func__,
+			 entry->ifname, activate, &ipaddr);
+		goto done_unlock_put;
+	} else if (ipv4_is_loopback(ipaddr)) {
+		IF_DEBUG("qtaguid: iface_stat: create(%s): "
+			 "ignore loopback dev. ip=%pI4\n", ifname, &ipaddr);
+		goto done_unlock_put;
+	}
+
+	new_iface = iface_alloc(net_dev);
+	IF_DEBUG("qtaguid: iface_stat: create(%s): done "
+		 "entry=%p ip=%pI4\n", ifname, new_iface, &ipaddr);
+done_unlock_put:
+	spin_unlock_bh(&iface_stat_list_lock);
+done_put:
+	if (in_dev)
+		in_dev_put(in_dev);
+}
+
+static void iface_stat_create_ipv6(struct net_device *net_dev,
+				   struct inet6_ifaddr *ifa)
+{
+	struct in_device *in_dev;
+	const char *ifname;
+	struct iface_stat *entry;
+	struct iface_stat *new_iface;
+	int addr_type;
+
+	IF_DEBUG("qtaguid: iface_stat: create6(): ifa=%p netdev=%p->name=%s\n",
+		 ifa, net_dev, net_dev ? net_dev->name : "");
+	if (!net_dev) {
+		pr_err("qtaguid: iface_stat: create6(): no net dev!\n");
+		return;
+	}
+	ifname = net_dev->name;
+
+	in_dev = in_dev_get(net_dev);
+	if (!in_dev) {
+		pr_err("qtaguid: iface_stat: create6(%s): no inet dev\n",
+		       ifname);
+		return;
+	}
+
+	IF_DEBUG("qtaguid: iface_stat: create6(%s): in_dev=%p\n",
+		 ifname, in_dev);
+
+	if (!ifa) {
+		IF_DEBUG("qtaguid: iface_stat: create6(%s): no matching IP\n",
+			 ifname);
+		goto done_put;
+	}
+	addr_type = ipv6_addr_type(&ifa->addr);
+
+	spin_lock_bh(&iface_stat_list_lock);
+	entry = get_iface_entry(ifname);
+	if (entry != NULL) {
+		bool activate = !(addr_type & IPV6_ADDR_LOOPBACK);
+		IF_DEBUG("qtaguid: %s(%s): entry=%p\n", __func__,
+			 ifname, entry);
+		iface_check_stats_reset_and_adjust(net_dev, entry);
+		_iface_stat_set_active(entry, net_dev, activate);
+		IF_DEBUG("qtaguid: %s(%s): "
+			 "tracking now %d on ip=%pI6c\n", __func__,
+			 entry->ifname, activate, &ifa->addr);
+		goto done_unlock_put;
+	} else if (addr_type & IPV6_ADDR_LOOPBACK) {
+		IF_DEBUG("qtaguid: %s(%s): "
+			 "ignore loopback dev. ip=%pI6c\n", __func__,
+			 ifname, &ifa->addr);
+		goto done_unlock_put;
+	}
+
+	new_iface = iface_alloc(net_dev);
+	IF_DEBUG("qtaguid: iface_stat: create6(%s): done "
+		 "entry=%p ip=%pI6c\n", ifname, new_iface, &ifa->addr);
+
+done_unlock_put:
+	spin_unlock_bh(&iface_stat_list_lock);
+done_put:
+	in_dev_put(in_dev);
+}
+
+static struct sock_tag *get_sock_stat_nl(const struct sock *sk)
+{
+	MT_DEBUG("qtaguid: get_sock_stat_nl(sk=%p)\n", sk);
+	return sock_tag_tree_search(&sock_tag_tree, sk);
+}
+
+static struct sock_tag *get_sock_stat(const struct sock *sk)
+{
+	struct sock_tag *sock_tag_entry;
+	MT_DEBUG("qtaguid: get_sock_stat(sk=%p)\n", sk);
+	if (!sk)
+		return NULL;
+	spin_lock_bh(&sock_tag_list_lock);
+	sock_tag_entry = get_sock_stat_nl(sk);
+	spin_unlock_bh(&sock_tag_list_lock);
+	return sock_tag_entry;
+}
+
+static void
+data_counters_update(struct data_counters *dc, int set,
+		     enum ifs_tx_rx direction, int proto, int bytes)
+{
+	switch (proto) {
+	case IPPROTO_TCP:
+		dc_add_byte_packets(dc, set, direction, IFS_TCP, bytes, 1);
+		break;
+	case IPPROTO_UDP:
+		dc_add_byte_packets(dc, set, direction, IFS_UDP, bytes, 1);
+		break;
+	case IPPROTO_IP:
+	default:
+		dc_add_byte_packets(dc, set, direction, IFS_PROTO_OTHER, bytes,
+				    1);
+		break;
+	}
+}
+
+/*
+ * Update stats for the specified interface. Do nothing if the entry
+ * does not exist (when a device was never configured with an IP address).
+ * Called when an device is being unregistered.
+ */
+static void iface_stat_update(struct net_device *net_dev, bool stash_only)
+{
+	struct rtnl_link_stats64 dev_stats, *stats;
+	struct iface_stat *entry;
+
+	stats = dev_get_stats(net_dev, &dev_stats);
+	spin_lock_bh(&iface_stat_list_lock);
+	entry = get_iface_entry(net_dev->name);
+	if (entry == NULL) {
+		IF_DEBUG("qtaguid: iface_stat: update(%s): not tracked\n",
+			 net_dev->name);
+		spin_unlock_bh(&iface_stat_list_lock);
+		return;
+	}
+
+	IF_DEBUG("qtaguid: %s(%s): entry=%p\n", __func__,
+		 net_dev->name, entry);
+	if (!entry->active) {
+		IF_DEBUG("qtaguid: %s(%s): already disabled\n", __func__,
+			 net_dev->name);
+		spin_unlock_bh(&iface_stat_list_lock);
+		return;
+	}
+
+	if (stash_only) {
+		entry->last_known[IFS_TX].bytes = stats->tx_bytes;
+		entry->last_known[IFS_TX].packets = stats->tx_packets;
+		entry->last_known[IFS_RX].bytes = stats->rx_bytes;
+		entry->last_known[IFS_RX].packets = stats->rx_packets;
+		entry->last_known_valid = true;
+		IF_DEBUG("qtaguid: %s(%s): "
+			 "dev stats stashed rx/tx=%llu/%llu\n", __func__,
+			 net_dev->name, stats->rx_bytes, stats->tx_bytes);
+		spin_unlock_bh(&iface_stat_list_lock);
+		return;
+	}
+	entry->totals[IFS_TX].bytes += stats->tx_bytes;
+	entry->totals[IFS_TX].packets += stats->tx_packets;
+	entry->totals[IFS_RX].bytes += stats->rx_bytes;
+	entry->totals[IFS_RX].packets += stats->rx_packets;
+	/* We don't need the last_known[] anymore */
+	entry->last_known_valid = false;
+	_iface_stat_set_active(entry, net_dev, false);
+	IF_DEBUG("qtaguid: %s(%s): "
+		 "disable tracking. rx/tx=%llu/%llu\n", __func__,
+		 net_dev->name, stats->rx_bytes, stats->tx_bytes);
+	spin_unlock_bh(&iface_stat_list_lock);
+}
+
+static void tag_stat_update(struct tag_stat *tag_entry,
+			enum ifs_tx_rx direction, int proto, int bytes)
+{
+	int active_set;
+	active_set = get_active_counter_set(tag_entry->tn.tag);
+	MT_DEBUG("qtaguid: tag_stat_update(tag=0x%llx (uid=%u) set=%d "
+		 "dir=%d proto=%d bytes=%d)\n",
+		 tag_entry->tn.tag, get_uid_from_tag(tag_entry->tn.tag),
+		 active_set, direction, proto, bytes);
+	data_counters_update(&tag_entry->counters, active_set, direction,
+			     proto, bytes);
+	if (tag_entry->parent_counters)
+		data_counters_update(tag_entry->parent_counters, active_set,
+				     direction, proto, bytes);
+}
+
+/*
+ * Create a new entry for tracking the specified {acct_tag,uid_tag} within
+ * the interface.
+ * iface_entry->tag_stat_list_lock should be held.
+ */
+static struct tag_stat *create_if_tag_stat(struct iface_stat *iface_entry,
+					   tag_t tag)
+{
+	struct tag_stat *new_tag_stat_entry = NULL;
+	IF_DEBUG("qtaguid: iface_stat: %s(): ife=%p tag=0x%llx"
+		 " (uid=%u)\n", __func__,
+		 iface_entry, tag, get_uid_from_tag(tag));
+	new_tag_stat_entry = kzalloc(sizeof(*new_tag_stat_entry), GFP_ATOMIC);
+	if (!new_tag_stat_entry) {
+		pr_err("qtaguid: iface_stat: tag stat alloc failed\n");
+		goto done;
+	}
+	new_tag_stat_entry->tn.tag = tag;
+	tag_stat_tree_insert(new_tag_stat_entry, &iface_entry->tag_stat_tree);
+done:
+	return new_tag_stat_entry;
+}
+
+static void if_tag_stat_update(const char *ifname, uid_t uid,
+			       const struct sock *sk, enum ifs_tx_rx direction,
+			       int proto, int bytes)
+{
+	struct tag_stat *tag_stat_entry;
+	tag_t tag, acct_tag;
+	tag_t uid_tag;
+	struct data_counters *uid_tag_counters;
+	struct sock_tag *sock_tag_entry;
+	struct iface_stat *iface_entry;
+	struct tag_stat *new_tag_stat;
+	MT_DEBUG("qtaguid: if_tag_stat_update(ifname=%s "
+		"uid=%u sk=%p dir=%d proto=%d bytes=%d)\n",
+		 ifname, uid, sk, direction, proto, bytes);
+
+
+	iface_entry = get_iface_entry(ifname);
+	if (!iface_entry) {
+		pr_err("qtaguid: iface_stat: stat_update() %s not found\n",
+		       ifname);
+		return;
+	}
+	/* It is ok to process data when an iface_entry is inactive */
+
+	MT_DEBUG("qtaguid: iface_stat: stat_update() dev=%s entry=%p\n",
+		 ifname, iface_entry);
+
+	/*
+	 * Look for a tagged sock.
+	 * It will have an acct_uid.
+	 */
+	sock_tag_entry = get_sock_stat(sk);
+	if (sock_tag_entry) {
+		tag = sock_tag_entry->tag;
+		acct_tag = get_atag_from_tag(tag);
+		uid_tag = get_utag_from_tag(tag);
+	} else {
+		acct_tag = make_atag_from_value(0);
+		tag = combine_atag_with_uid(acct_tag, uid);
+		uid_tag = make_tag_from_uid(uid);
+	}
+	MT_DEBUG("qtaguid: iface_stat: stat_update(): "
+		 " looking for tag=0x%llx (uid=%u) in ife=%p\n",
+		 tag, get_uid_from_tag(tag), iface_entry);
+	/* Loop over tag list under this interface for {acct_tag,uid_tag} */
+	spin_lock_bh(&iface_entry->tag_stat_list_lock);
+
+	tag_stat_entry = tag_stat_tree_search(&iface_entry->tag_stat_tree,
+					      tag);
+	if (tag_stat_entry) {
+		/*
+		 * Updating the {acct_tag, uid_tag} entry handles both stats:
+		 * {0, uid_tag} will also get updated.
+		 */
+		tag_stat_update(tag_stat_entry, direction, proto, bytes);
+		spin_unlock_bh(&iface_entry->tag_stat_list_lock);
+		return;
+	}
+
+	/* Loop over tag list under this interface for {0,uid_tag} */
+	tag_stat_entry = tag_stat_tree_search(&iface_entry->tag_stat_tree,
+					      uid_tag);
+	if (!tag_stat_entry) {
+		/* Here: the base uid_tag did not exist */
+		/*
+		 * No parent counters. So
+		 *  - No {0, uid_tag} stats and no {acc_tag, uid_tag} stats.
+		 */
+		new_tag_stat = create_if_tag_stat(iface_entry, uid_tag);
+		uid_tag_counters = &new_tag_stat->counters;
+	} else {
+		uid_tag_counters = &tag_stat_entry->counters;
+	}
+
+	if (acct_tag) {
+		new_tag_stat = create_if_tag_stat(iface_entry, tag);
+		new_tag_stat->parent_counters = uid_tag_counters;
+	}
+	tag_stat_update(new_tag_stat, direction, proto, bytes);
+	spin_unlock_bh(&iface_entry->tag_stat_list_lock);
+}
+
+static int iface_netdev_event_handler(struct notifier_block *nb,
+				      unsigned long event, void *ptr) {
+	struct net_device *dev = ptr;
+
+	if (unlikely(module_passive))
+		return NOTIFY_DONE;
+
+	IF_DEBUG("qtaguid: iface_stat: netdev_event(): "
+		 "ev=0x%lx/%s netdev=%p->name=%s\n",
+		 event, netdev_evt_str(event), dev, dev ? dev->name : "");
+
+	switch (event) {
+	case NETDEV_UP:
+		iface_stat_create(dev, NULL);
+		atomic64_inc(&qtu_events.iface_events);
+		break;
+	case NETDEV_DOWN:
+	case NETDEV_UNREGISTER:
+		iface_stat_update(dev, event == NETDEV_DOWN);
+		atomic64_inc(&qtu_events.iface_events);
+		break;
+	}
+	return NOTIFY_DONE;
+}
+
+static int iface_inet6addr_event_handler(struct notifier_block *nb,
+					 unsigned long event, void *ptr)
+{
+	struct inet6_ifaddr *ifa = ptr;
+	struct net_device *dev;
+
+	if (unlikely(module_passive))
+		return NOTIFY_DONE;
+
+	IF_DEBUG("qtaguid: iface_stat: inet6addr_event(): "
+		 "ev=0x%lx/%s ifa=%p\n",
+		 event, netdev_evt_str(event), ifa);
+
+	switch (event) {
+	case NETDEV_UP:
+		BUG_ON(!ifa || !ifa->idev);
+		dev = (struct net_device *)ifa->idev->dev;
+		iface_stat_create_ipv6(dev, ifa);
+		atomic64_inc(&qtu_events.iface_events);
+		break;
+	case NETDEV_DOWN:
+	case NETDEV_UNREGISTER:
+		BUG_ON(!ifa || !ifa->idev);
+		dev = (struct net_device *)ifa->idev->dev;
+		iface_stat_update(dev, event == NETDEV_DOWN);
+		atomic64_inc(&qtu_events.iface_events);
+		break;
+	}
+	return NOTIFY_DONE;
+}
+
+static int iface_inetaddr_event_handler(struct notifier_block *nb,
+					unsigned long event, void *ptr)
+{
+	struct in_ifaddr *ifa = ptr;
+	struct net_device *dev;
+
+	if (unlikely(module_passive))
+		return NOTIFY_DONE;
+
+	IF_DEBUG("qtaguid: iface_stat: inetaddr_event(): "
+		 "ev=0x%lx/%s ifa=%p\n",
+		 event, netdev_evt_str(event), ifa);
+
+	switch (event) {
+	case NETDEV_UP:
+		BUG_ON(!ifa || !ifa->ifa_dev);
+		dev = ifa->ifa_dev->dev;
+		iface_stat_create(dev, ifa);
+		atomic64_inc(&qtu_events.iface_events);
+		break;
+	case NETDEV_DOWN:
+	case NETDEV_UNREGISTER:
+		BUG_ON(!ifa || !ifa->ifa_dev);
+		dev = ifa->ifa_dev->dev;
+		iface_stat_update(dev, event == NETDEV_DOWN);
+		atomic64_inc(&qtu_events.iface_events);
+		break;
+	}
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block iface_netdev_notifier_blk = {
+	.notifier_call = iface_netdev_event_handler,
+};
+
+static struct notifier_block iface_inetaddr_notifier_blk = {
+	.notifier_call = iface_inetaddr_event_handler,
+};
+
+static struct notifier_block iface_inet6addr_notifier_blk = {
+	.notifier_call = iface_inet6addr_event_handler,
+};
+
+static int __init iface_stat_init(struct proc_dir_entry *parent_procdir)
+{
+	int err;
+
+	iface_stat_procdir = proc_mkdir(iface_stat_procdirname, parent_procdir);
+	if (!iface_stat_procdir) {
+		pr_err("qtaguid: iface_stat: init failed to create proc entry\n");
+		err = -1;
+		goto err;
+	}
+
+	iface_stat_all_procfile = create_proc_entry(iface_stat_all_procfilename,
+						    proc_iface_perms,
+						    parent_procdir);
+	if (!iface_stat_all_procfile) {
+		pr_err("qtaguid: iface_stat: init "
+		       " failed to create stat_all proc entry\n");
+		err = -1;
+		goto err_zap_entry;
+	}
+	iface_stat_all_procfile->read_proc = iface_stat_all_proc_read;
+
+
+	err = register_netdevice_notifier(&iface_netdev_notifier_blk);
+	if (err) {
+		pr_err("qtaguid: iface_stat: init "
+		       "failed to register dev event handler\n");
+		goto err_zap_all_stats_entry;
+	}
+	err = register_inetaddr_notifier(&iface_inetaddr_notifier_blk);
+	if (err) {
+		pr_err("qtaguid: iface_stat: init "
+		       "failed to register ipv4 dev event handler\n");
+		goto err_unreg_nd;
+	}
+
+	err = register_inet6addr_notifier(&iface_inet6addr_notifier_blk);
+	if (err) {
+		pr_err("qtaguid: iface_stat: init "
+		       "failed to register ipv6 dev event handler\n");
+		goto err_unreg_ip4_addr;
+	}
+	return 0;
+
+err_unreg_ip4_addr:
+	unregister_inetaddr_notifier(&iface_inetaddr_notifier_blk);
+err_unreg_nd:
+	unregister_netdevice_notifier(&iface_netdev_notifier_blk);
+err_zap_all_stats_entry:
+	remove_proc_entry(iface_stat_all_procfilename, parent_procdir);
+err_zap_entry:
+	remove_proc_entry(iface_stat_procdirname, parent_procdir);
+err:
+	return err;
+}
+
+static struct sock *qtaguid_find_sk(const struct sk_buff *skb,
+				    struct xt_action_param *par)
+{
+	struct sock *sk;
+	unsigned int hook_mask = (1 << par->hooknum);
+
+	MT_DEBUG("qtaguid: find_sk(skb=%p) hooknum=%d family=%d\n", skb,
+		 par->hooknum, par->family);
+
+	/*
+	 * Let's not abuse the the xt_socket_get*_sk(), or else it will
+	 * return garbage SKs.
+	 */
+	if (!(hook_mask & XT_SOCKET_SUPPORTED_HOOKS))
+		return NULL;
+
+	switch (par->family) {
+	case NFPROTO_IPV6:
+		sk = xt_socket_get6_sk(skb, par);
+		break;
+	case NFPROTO_IPV4:
+		sk = xt_socket_get4_sk(skb, par);
+		break;
+	default:
+		return NULL;
+	}
+
+	/*
+	 * Seems to be issues on the file ptr for TCP_TIME_WAIT SKs.
+	 * http://kerneltrap.org/mailarchive/linux-netdev/2010/10/21/6287959
+	 * Not fixed in 3.0-r3 :(
+	 */
+	if (sk) {
+		MT_DEBUG("qtaguid: %p->sk_proto=%u "
+			 "->sk_state=%d\n", sk, sk->sk_protocol, sk->sk_state);
+		if (sk->sk_state  == TCP_TIME_WAIT) {
+			xt_socket_put_sk(sk);
+			sk = NULL;
+		}
+	}
+	return sk;
+}
+
+static void account_for_uid(const struct sk_buff *skb,
+			    const struct sock *alternate_sk, uid_t uid,
+			    struct xt_action_param *par)
+{
+	const struct net_device *el_dev;
+
+	if (!skb->dev) {
+		MT_DEBUG("qtaguid[%d]: no skb->dev\n", par->hooknum);
+		el_dev = par->in ? : par->out;
+	} else {
+		const struct net_device *other_dev;
+		el_dev = skb->dev;
+		other_dev = par->in ? : par->out;
+		if (el_dev != other_dev) {
+			MT_DEBUG("qtaguid[%d]: skb->dev=%p %s vs "
+				"par->(in/out)=%p %s\n",
+				par->hooknum, el_dev, el_dev->name, other_dev,
+				other_dev->name);
+		}
+	}
+
+	if (unlikely(!el_dev)) {
+		pr_info("qtaguid[%d]: no par->in/out?!!\n", par->hooknum);
+	} else if (unlikely(!el_dev->name)) {
+		pr_info("qtaguid[%d]: no dev->name?!!\n", par->hooknum);
+	} else {
+		MT_DEBUG("qtaguid[%d]: dev name=%s type=%d\n",
+			 par->hooknum,
+			 el_dev->name,
+			 el_dev->type);
+
+		if_tag_stat_update(el_dev->name, uid,
+				skb->sk ? skb->sk : alternate_sk,
+				par->in ? IFS_RX : IFS_TX,
+				ip_hdr(skb)->protocol, skb->len);
+	}
+}
+
+static bool qtaguid_mt(const struct sk_buff *skb, struct xt_action_param *par)
+{
+	const struct xt_qtaguid_match_info *info = par->matchinfo;
+	const struct file *filp;
+	bool got_sock = false;
+	struct sock *sk;
+	uid_t sock_uid;
+	bool res;
+
+	if (unlikely(module_passive))
+		return (info->match ^ info->invert) == 0;
+
+	MT_DEBUG("qtaguid[%d]: entered skb=%p par->in=%p/out=%p fam=%d\n",
+		 par->hooknum, skb, par->in, par->out, par->family);
+
+	atomic64_inc(&qtu_events.match_calls);
+	if (skb == NULL) {
+		res = (info->match ^ info->invert) == 0;
+		goto ret_res;
+	}
+
+	sk = skb->sk;
+
+	if (sk == NULL) {
+		/*
+		 * A missing sk->sk_socket happens when packets are in-flight
+		 * and the matching socket is already closed and gone.
+		 */
+		sk = qtaguid_find_sk(skb, par);
+		/*
+		 * If we got the socket from the find_sk(), we will need to put
+		 * it back, as nf_tproxy_get_sock_v4() got it.
+		 */
+		got_sock = sk;
+		if (sk)
+			atomic64_inc(&qtu_events.match_found_sk_in_ct);
+		else
+			atomic64_inc(&qtu_events.match_found_no_sk_in_ct);
+	} else {
+		atomic64_inc(&qtu_events.match_found_sk);
+	}
+	MT_DEBUG("qtaguid[%d]: sk=%p got_sock=%d proto=%d\n",
+		par->hooknum, sk, got_sock, ip_hdr(skb)->protocol);
+	if (sk != NULL) {
+		MT_DEBUG("qtaguid[%d]: sk=%p->sk_socket=%p->file=%p\n",
+			par->hooknum, sk, sk->sk_socket,
+			sk->sk_socket ? sk->sk_socket->file : (void *)-1LL);
+		filp = sk->sk_socket ? sk->sk_socket->file : NULL;
+		MT_DEBUG("qtaguid[%d]: filp...uid=%u\n",
+			par->hooknum, filp ? filp->f_cred->fsuid : -1);
+	}
+
+	if (sk == NULL || sk->sk_socket == NULL) {
+		/*
+		 * Here, the qtaguid_find_sk() using connection tracking
+		 * couldn't find the owner, so for now we just count them
+		 * against the system.
+		 */
+		/*
+		 * TODO: unhack how to force just accounting.
+		 * For now we only do iface stats when the uid-owner is not
+		 * requested.
+		 */
+		if (!(info->match & XT_QTAGUID_UID))
+			account_for_uid(skb, sk, 0, par);
+		MT_DEBUG("qtaguid[%d]: leaving (sk?sk->sk_socket)=%p\n",
+			par->hooknum,
+			sk ? sk->sk_socket : NULL);
+		res = (info->match ^ info->invert) == 0;
+		atomic64_inc(&qtu_events.match_no_sk);
+		goto put_sock_ret_res;
+	} else if (info->match & info->invert & XT_QTAGUID_SOCKET) {
+		res = false;
+		goto put_sock_ret_res;
+	}
+	filp = sk->sk_socket->file;
+	if (filp == NULL) {
+		MT_DEBUG("qtaguid[%d]: leaving filp=NULL\n", par->hooknum);
+		account_for_uid(skb, sk, 0, par);
+		res = ((info->match ^ info->invert) &
+			(XT_QTAGUID_UID | XT_QTAGUID_GID)) == 0;
+		atomic64_inc(&qtu_events.match_no_sk_file);
+		goto put_sock_ret_res;
+	}
+	sock_uid = filp->f_cred->fsuid;
+	/*
+	 * TODO: unhack how to force just accounting.
+	 * For now we only do iface stats when the uid-owner is not requested
+	 */
+	if (!(info->match & XT_QTAGUID_UID))
+		account_for_uid(skb, sk, sock_uid, par);
+
+	/*
+	 * The following two tests fail the match when:
+	 *    id not in range AND no inverted condition requested
+	 * or id     in range AND    inverted condition requested
+	 * Thus (!a && b) || (a && !b) == a ^ b
+	 */
+	if (info->match & XT_QTAGUID_UID)
+		if ((filp->f_cred->fsuid >= info->uid_min &&
+		     filp->f_cred->fsuid <= info->uid_max) ^
+		    !(info->invert & XT_QTAGUID_UID)) {
+			MT_DEBUG("qtaguid[%d]: leaving uid not matching\n",
+				 par->hooknum);
+			res = false;
+			goto put_sock_ret_res;
+		}
+	if (info->match & XT_QTAGUID_GID)
+		if ((filp->f_cred->fsgid >= info->gid_min &&
+				filp->f_cred->fsgid <= info->gid_max) ^
+			!(info->invert & XT_QTAGUID_GID)) {
+			MT_DEBUG("qtaguid[%d]: leaving gid not matching\n",
+				par->hooknum);
+			res = false;
+			goto put_sock_ret_res;
+		}
+
+	MT_DEBUG("qtaguid[%d]: leaving matched\n", par->hooknum);
+	res = true;
+
+put_sock_ret_res:
+	if (got_sock)
+		xt_socket_put_sk(sk);
+ret_res:
+	MT_DEBUG("qtaguid[%d]: left %d\n", par->hooknum, res);
+	return res;
+}
+
+#ifdef DDEBUG
+/* This function is not in xt_qtaguid_print.c because of locks visibility */
+static void prdebug_full_state(int indent_level, const char *fmt, ...)
+{
+	va_list args;
+	char *fmt_buff;
+	char *buff;
+
+	if (!unlikely(qtaguid_debug_mask & DDEBUG_MASK))
+		return;
+
+	fmt_buff = kasprintf(GFP_ATOMIC,
+			     "qtaguid: %s(): %s {\n", __func__, fmt);
+	BUG_ON(!fmt_buff);
+	va_start(args, fmt);
+	buff = kvasprintf(GFP_ATOMIC,
+			  fmt_buff, args);
+	BUG_ON(!buff);
+	pr_debug("%s", buff);
+	kfree(fmt_buff);
+	kfree(buff);
+	va_end(args);
+
+	spin_lock_bh(&sock_tag_list_lock);
+	prdebug_sock_tag_tree(indent_level, &sock_tag_tree);
+	spin_unlock_bh(&sock_tag_list_lock);
+
+	spin_lock_bh(&sock_tag_list_lock);
+	spin_lock_bh(&uid_tag_data_tree_lock);
+	prdebug_uid_tag_data_tree(indent_level, &uid_tag_data_tree);
+	prdebug_proc_qtu_data_tree(indent_level, &proc_qtu_data_tree);
+	spin_unlock_bh(&uid_tag_data_tree_lock);
+	spin_unlock_bh(&sock_tag_list_lock);
+
+	spin_lock_bh(&iface_stat_list_lock);
+	prdebug_iface_stat_list(indent_level, &iface_stat_list);
+	spin_unlock_bh(&iface_stat_list_lock);
+
+	pr_debug("qtaguid: %s(): }\n", __func__);
+}
+#else
+static void prdebug_full_state(int indent_level, const char *fmt, ...) {}
+#endif
+
+/*
+ * Procfs reader to get all active socket tags using style "1)" as described in
+ * fs/proc/generic.c
+ */
+static int qtaguid_ctrl_proc_read(char *page, char **num_items_returned,
+				  off_t items_to_skip, int char_count, int *eof,
+				  void *data)
+{
+	char *outp = page;
+	int len;
+	uid_t uid;
+	struct rb_node *node;
+	struct sock_tag *sock_tag_entry;
+	int item_index = 0;
+	int indent_level = 0;
+	long f_count;
+
+	if (unlikely(module_passive)) {
+		*eof = 1;
+		return 0;
+	}
+
+	if (*eof)
+		return 0;
+
+	CT_DEBUG("qtaguid: proc ctrl page=%p off=%ld char_count=%d *eof=%d\n",
+		page, items_to_skip, char_count, *eof);
+
+	spin_lock_bh(&sock_tag_list_lock);
+	for (node = rb_first(&sock_tag_tree);
+	     node;
+	     node = rb_next(node)) {
+		if (item_index++ < items_to_skip)
+			continue;
+		sock_tag_entry = rb_entry(node, struct sock_tag, sock_node);
+		uid = get_uid_from_tag(sock_tag_entry->tag);
+		CT_DEBUG("qtaguid: proc_read(): sk=%p tag=0x%llx (uid=%u) "
+			 "pid=%u\n",
+			 sock_tag_entry->sk,
+			 sock_tag_entry->tag,
+			 uid,
+			 sock_tag_entry->pid
+			);
+		f_count = atomic_long_read(
+			&sock_tag_entry->socket->file->f_count);
+		len = snprintf(outp, char_count,
+			       "sock=%p tag=0x%llx (uid=%u) pid=%u "
+			       "f_count=%lu\n",
+			       sock_tag_entry->sk,
+			       sock_tag_entry->tag, uid,
+			       sock_tag_entry->pid, f_count);
+		if (len >= char_count) {
+			spin_unlock_bh(&sock_tag_list_lock);
+			*outp = '\0';
+			return outp - page;
+		}
+		outp += len;
+		char_count -= len;
+		(*num_items_returned)++;
+	}
+	spin_unlock_bh(&sock_tag_list_lock);
+
+	if (item_index++ >= items_to_skip) {
+		len = snprintf(outp, char_count,
+			       "events: sockets_tagged=%llu "
+			       "sockets_untagged=%llu "
+			       "counter_set_changes=%llu "
+			       "delete_cmds=%llu "
+			       "iface_events=%llu "
+			       "match_calls=%llu "
+			       "match_found_sk=%llu "
+			       "match_found_sk_in_ct=%llu "
+			       "match_found_no_sk_in_ct=%llu "
+			       "match_no_sk=%llu "
+			       "match_no_sk_file=%llu\n",
+			       atomic64_read(&qtu_events.sockets_tagged),
+			       atomic64_read(&qtu_events.sockets_untagged),
+			       atomic64_read(&qtu_events.counter_set_changes),
+			       atomic64_read(&qtu_events.delete_cmds),
+			       atomic64_read(&qtu_events.iface_events),
+			       atomic64_read(&qtu_events.match_calls),
+			       atomic64_read(&qtu_events.match_found_sk),
+			       atomic64_read(&qtu_events.match_found_sk_in_ct),
+			       atomic64_read(
+				       &qtu_events.match_found_no_sk_in_ct),
+			       atomic64_read(&qtu_events.match_no_sk),
+			       atomic64_read(&qtu_events.match_no_sk_file));
+		if (len >= char_count) {
+			*outp = '\0';
+			return outp - page;
+		}
+		outp += len;
+		char_count -= len;
+		(*num_items_returned)++;
+	}
+
+	/* Count the following as part of the last item_index */
+	if (item_index > items_to_skip) {
+		prdebug_full_state(indent_level, "proc ctrl");
+	}
+
+	*eof = 1;
+	return outp - page;
+}
+
+/*
+ * Delete socket tags, and stat tags associated with a given
+ * accouting tag and uid.
+ */
+static int ctrl_cmd_delete(const char *input)
+{
+	char cmd;
+	uid_t uid;
+	uid_t entry_uid;
+	tag_t acct_tag;
+	tag_t tag;
+	int res, argc;
+	struct iface_stat *iface_entry;
+	struct rb_node *node;
+	struct sock_tag *st_entry;
+	struct rb_root st_to_free_tree = RB_ROOT;
+	struct tag_stat *ts_entry;
+	struct tag_counter_set *tcs_entry;
+	struct tag_ref *tr_entry;
+	struct uid_tag_data *utd_entry;
+
+	argc = sscanf(input, "%c %llu %u", &cmd, &acct_tag, &uid);
+	CT_DEBUG("qtaguid: ctrl_delete(%s): argc=%d cmd=%c "
+		 "user_tag=0x%llx uid=%u\n", input, argc, cmd,
+		 acct_tag, uid);
+	if (argc < 2) {
+		res = -EINVAL;
+		goto err;
+	}
+	if (!valid_atag(acct_tag)) {
+		pr_info("qtaguid: ctrl_delete(%s): invalid tag\n", input);
+		res = -EINVAL;
+		goto err;
+	}
+	if (argc < 3) {
+		uid = current_fsuid();
+	} else if (!can_impersonate_uid(uid)) {
+		pr_info("qtaguid: ctrl_delete(%s): "
+			"insufficient priv from pid=%u tgid=%u uid=%u\n",
+			input, current->pid, current->tgid, current_fsuid());
+		res = -EPERM;
+		goto err;
+	}
+
+	tag = combine_atag_with_uid(acct_tag, uid);
+	CT_DEBUG("qtaguid: ctrl_delete(%s): "
+		 "looking for tag=0x%llx (uid=%u)\n",
+		 input, tag, uid);
+
+	/* Delete socket tags */
+	spin_lock_bh(&sock_tag_list_lock);
+	node = rb_first(&sock_tag_tree);
+	while (node) {
+		st_entry = rb_entry(node, struct sock_tag, sock_node);
+		entry_uid = get_uid_from_tag(st_entry->tag);
+		node = rb_next(node);
+		if (entry_uid != uid)
+			continue;
+
+		CT_DEBUG("qtaguid: ctrl_delete(%s): st tag=0x%llx (uid=%u)\n",
+			 input, st_entry->tag, entry_uid);
+
+		if (!acct_tag || st_entry->tag == tag) {
+			rb_erase(&st_entry->sock_node, &sock_tag_tree);
+			/* Can't sockfd_put() within spinlock, do it later. */
+			sock_tag_tree_insert(st_entry, &st_to_free_tree);
+			tr_entry = lookup_tag_ref(st_entry->tag, NULL);
+			BUG_ON(tr_entry->num_sock_tags <= 0);
+			tr_entry->num_sock_tags--;
+			/*
+			 * TODO: remove if, and start failing.
+			 * This is a hack to work around the fact that in some
+			 * places we have "if (IS_ERR_OR_NULL(pqd_entry))"
+			 * and are trying to work around apps
+			 * that didn't open the /dev/xt_qtaguid.
+			 */
+			if (st_entry->list.next && st_entry->list.prev)
+				list_del(&st_entry->list);
+		}
+	}
+	spin_unlock_bh(&sock_tag_list_lock);
+
+	sock_tag_tree_erase(&st_to_free_tree);
+
+	/* Delete tag counter-sets */
+	spin_lock_bh(&tag_counter_set_list_lock);
+	/* Counter sets are only on the uid tag, not full tag */
+	tcs_entry = tag_counter_set_tree_search(&tag_counter_set_tree, tag);
+	if (tcs_entry) {
+		CT_DEBUG("qtaguid: ctrl_delete(%s): "
+			 "erase tcs: tag=0x%llx (uid=%u) set=%d\n",
+			 input,
+			 tcs_entry->tn.tag,
+			 get_uid_from_tag(tcs_entry->tn.tag),
+			 tcs_entry->active_set);
+		rb_erase(&tcs_entry->tn.node, &tag_counter_set_tree);
+		kfree(tcs_entry);
+	}
+	spin_unlock_bh(&tag_counter_set_list_lock);
+
+	/*
+	 * If acct_tag is 0, then all entries belonging to uid are
+	 * erased.
+	 */
+	spin_lock_bh(&iface_stat_list_lock);
+	list_for_each_entry(iface_entry, &iface_stat_list, list) {
+		spin_lock_bh(&iface_entry->tag_stat_list_lock);
+		node = rb_first(&iface_entry->tag_stat_tree);
+		while (node) {
+			ts_entry = rb_entry(node, struct tag_stat, tn.node);
+			entry_uid = get_uid_from_tag(ts_entry->tn.tag);
+			node = rb_next(node);
+
+			CT_DEBUG("qtaguid: ctrl_delete(%s): "
+				 "ts tag=0x%llx (uid=%u)\n",
+				 input, ts_entry->tn.tag, entry_uid);
+
+			if (entry_uid != uid)
+				continue;
+			if (!acct_tag || ts_entry->tn.tag == tag) {
+				CT_DEBUG("qtaguid: ctrl_delete(%s): "
+					 "erase ts: %s 0x%llx %u\n",
+					 input, iface_entry->ifname,
+					 get_atag_from_tag(ts_entry->tn.tag),
+					 entry_uid);
+				rb_erase(&ts_entry->tn.node,
+					 &iface_entry->tag_stat_tree);
+				kfree(ts_entry);
+			}
+		}
+		spin_unlock_bh(&iface_entry->tag_stat_list_lock);
+	}
+	spin_unlock_bh(&iface_stat_list_lock);
+
+	/* Cleanup the uid_tag_data */
+	spin_lock_bh(&uid_tag_data_tree_lock);
+	node = rb_first(&uid_tag_data_tree);
+	while (node) {
+		utd_entry = rb_entry(node, struct uid_tag_data, node);
+		entry_uid = utd_entry->uid;
+		node = rb_next(node);
+
+		CT_DEBUG("qtaguid: ctrl_delete(%s): "
+			 "utd uid=%u\n",
+			 input, entry_uid);
+
+		if (entry_uid != uid)
+			continue;
+		/*
+		 * Go over the tag_refs, and those that don't have
+		 * sock_tags using them are freed.
+		 */
+		put_tag_ref_tree(tag, utd_entry);
+		put_utd_entry(utd_entry);
+	}
+	spin_unlock_bh(&uid_tag_data_tree_lock);
+
+	atomic64_inc(&qtu_events.delete_cmds);
+	res = 0;
+
+err:
+	return res;
+}
+
+static int ctrl_cmd_counter_set(const char *input)
+{
+	char cmd;
+	uid_t uid = 0;
+	tag_t tag;
+	int res, argc;
+	struct tag_counter_set *tcs;
+	int counter_set;
+
+	argc = sscanf(input, "%c %d %u", &cmd, &counter_set, &uid);
+	CT_DEBUG("qtaguid: ctrl_counterset(%s): argc=%d cmd=%c "
+		 "set=%d uid=%u\n", input, argc, cmd,
+		 counter_set, uid);
+	if (argc != 3) {
+		res = -EINVAL;
+		goto err;
+	}
+	if (counter_set < 0 || counter_set >= IFS_MAX_COUNTER_SETS) {
+		pr_info("qtaguid: ctrl_counterset(%s): invalid counter_set range\n",
+			input);
+		res = -EINVAL;
+		goto err;
+	}
+	if (!can_manipulate_uids()) {
+		pr_info("qtaguid: ctrl_counterset(%s): "
+			"insufficient priv from pid=%u tgid=%u uid=%u\n",
+			input, current->pid, current->tgid, current_fsuid());
+		res = -EPERM;
+		goto err;
+	}
+
+	tag = make_tag_from_uid(uid);
+	spin_lock_bh(&tag_counter_set_list_lock);
+	tcs = tag_counter_set_tree_search(&tag_counter_set_tree, tag);
+	if (!tcs) {
+		tcs = kzalloc(sizeof(*tcs), GFP_ATOMIC);
+		if (!tcs) {
+			spin_unlock_bh(&tag_counter_set_list_lock);
+			pr_err("qtaguid: ctrl_counterset(%s): "
+			       "failed to alloc counter set\n",
+			       input);
+			res = -ENOMEM;
+			goto err;
+		}
+		tcs->tn.tag = tag;
+		tag_counter_set_tree_insert(tcs, &tag_counter_set_tree);
+		CT_DEBUG("qtaguid: ctrl_counterset(%s): added tcs tag=0x%llx "
+			 "(uid=%u) set=%d\n",
+			 input, tag, get_uid_from_tag(tag), counter_set);
+	}
+	tcs->active_set = counter_set;
+	spin_unlock_bh(&tag_counter_set_list_lock);
+	atomic64_inc(&qtu_events.counter_set_changes);
+	res = 0;
+
+err:
+	return res;
+}
+
+static int ctrl_cmd_tag(const char *input)
+{
+	char cmd;
+	int sock_fd = 0;
+	uid_t uid = 0;
+	tag_t acct_tag = make_atag_from_value(0);
+	tag_t full_tag;
+	struct socket *el_socket;
+	int res, argc;
+	struct sock_tag *sock_tag_entry;
+	struct tag_ref *tag_ref_entry;
+	struct uid_tag_data *uid_tag_data_entry;
+	struct proc_qtu_data *pqd_entry;
+
+	/* Unassigned args will get defaulted later. */
+	argc = sscanf(input, "%c %d %llu %u", &cmd, &sock_fd, &acct_tag, &uid);
+	CT_DEBUG("qtaguid: ctrl_tag(%s): argc=%d cmd=%c sock_fd=%d "
+		 "acct_tag=0x%llx uid=%u\n", input, argc, cmd, sock_fd,
+		 acct_tag, uid);
+	if (argc < 2) {
+		res = -EINVAL;
+		goto err;
+	}
+	el_socket = sockfd_lookup(sock_fd, &res);  /* This locks the file */
+	if (!el_socket) {
+		pr_info("qtaguid: ctrl_tag(%s): failed to lookup"
+			" sock_fd=%d err=%d\n", input, sock_fd, res);
+		goto err;
+	}
+	CT_DEBUG("qtaguid: ctrl_tag(%s): socket->...->f_count=%ld ->sk=%p\n",
+		 input, atomic_long_read(&el_socket->file->f_count),
+		 el_socket->sk);
+	if (argc < 3) {
+		acct_tag = make_atag_from_value(0);
+	} else if (!valid_atag(acct_tag)) {
+		pr_info("qtaguid: ctrl_tag(%s): invalid tag\n", input);
+		res = -EINVAL;
+		goto err_put;
+	}
+	CT_DEBUG("qtaguid: ctrl_tag(%s): "
+		 "pid=%u tgid=%u uid=%u euid=%u fsuid=%u "
+		 "in_group=%d in_egroup=%d\n",
+		 input, current->pid, current->tgid, current_uid(),
+		 current_euid(), current_fsuid(),
+		 in_group_p(proc_ctrl_write_gid),
+		 in_egroup_p(proc_ctrl_write_gid));
+	if (argc < 4) {
+		uid = current_fsuid();
+	} else if (!can_impersonate_uid(uid)) {
+		pr_info("qtaguid: ctrl_tag(%s): "
+			"insufficient priv from pid=%u tgid=%u uid=%u\n",
+			input, current->pid, current->tgid, current_fsuid());
+		res = -EPERM;
+		goto err_put;
+	}
+	full_tag = combine_atag_with_uid(acct_tag, uid);
+
+	spin_lock_bh(&sock_tag_list_lock);
+	sock_tag_entry = get_sock_stat_nl(el_socket->sk);
+	tag_ref_entry = get_tag_ref(full_tag, &uid_tag_data_entry);
+	if (IS_ERR(tag_ref_entry)) {
+		res = PTR_ERR(tag_ref_entry);
+		spin_unlock_bh(&sock_tag_list_lock);
+		goto err_put;
+	}
+	tag_ref_entry->num_sock_tags++;
+	if (sock_tag_entry) {
+		struct tag_ref *prev_tag_ref_entry;
+
+		CT_DEBUG("qtaguid: ctrl_tag(%s): retag for sk=%p "
+			 "st@%p ...->f_count=%ld\n",
+			 input, el_socket->sk, sock_tag_entry,
+			 atomic_long_read(&el_socket->file->f_count));
+		/*
+		 * This is a re-tagging, so release the sock_fd that was
+		 * locked at the time of the 1st tagging.
+		 * There is still the ref from this call's sockfd_lookup() so
+		 * it can be done within the spinlock.
+		 */
+		sockfd_put(sock_tag_entry->socket);
+		prev_tag_ref_entry = lookup_tag_ref(sock_tag_entry->tag,
+						    &uid_tag_data_entry);
+		BUG_ON(IS_ERR_OR_NULL(prev_tag_ref_entry));
+		BUG_ON(prev_tag_ref_entry->num_sock_tags <= 0);
+		prev_tag_ref_entry->num_sock_tags--;
+		sock_tag_entry->tag = full_tag;
+	} else {
+		CT_DEBUG("qtaguid: ctrl_tag(%s): newtag for sk=%p\n",
+			 input, el_socket->sk);
+		sock_tag_entry = kzalloc(sizeof(*sock_tag_entry),
+					 GFP_ATOMIC);
+		if (!sock_tag_entry) {
+			pr_err("qtaguid: ctrl_tag(%s): "
+			       "socket tag alloc failed\n",
+			       input);
+			spin_unlock_bh(&sock_tag_list_lock);
+			res = -ENOMEM;
+			goto err_tag_unref_put;
+		}
+		sock_tag_entry->sk = el_socket->sk;
+		sock_tag_entry->socket = el_socket;
+		sock_tag_entry->pid = current->tgid;
+		sock_tag_entry->tag = combine_atag_with_uid(acct_tag,
+							    uid);
+		spin_lock_bh(&uid_tag_data_tree_lock);
+		pqd_entry = proc_qtu_data_tree_search(
+			&proc_qtu_data_tree, current->tgid);
+		/*
+		 * TODO: remove if, and start failing.
+		 * At first, we want to catch user-space code that is not
+		 * opening the /dev/xt_qtaguid.
+		 */
+		if (IS_ERR_OR_NULL(pqd_entry))
+			pr_warn_once(
+				"qtaguid: %s(): "
+				"User space forgot to open /dev/xt_qtaguid? "
+				"pid=%u tgid=%u uid=%u\n", __func__,
+				current->pid, current->tgid,
+				current_fsuid());
+		else
+			list_add(&sock_tag_entry->list,
+				 &pqd_entry->sock_tag_list);
+		spin_unlock_bh(&uid_tag_data_tree_lock);
+
+		sock_tag_tree_insert(sock_tag_entry, &sock_tag_tree);
+		atomic64_inc(&qtu_events.sockets_tagged);
+	}
+	spin_unlock_bh(&sock_tag_list_lock);
+	/* We keep the ref to the socket (file) until it is untagged */
+	CT_DEBUG("qtaguid: ctrl_tag(%s): done st@%p ...->f_count=%ld\n",
+		 input, sock_tag_entry,
+		 atomic_long_read(&el_socket->file->f_count));
+	return 0;
+
+err_tag_unref_put:
+	BUG_ON(tag_ref_entry->num_sock_tags <= 0);
+	tag_ref_entry->num_sock_tags--;
+	free_tag_ref_from_utd_entry(tag_ref_entry, uid_tag_data_entry);
+err_put:
+	CT_DEBUG("qtaguid: ctrl_tag(%s): done. ...->f_count=%ld\n",
+		 input, atomic_long_read(&el_socket->file->f_count) - 1);
+	/* Release the sock_fd that was grabbed by sockfd_lookup(). */
+	sockfd_put(el_socket);
+	return res;
+
+err:
+	CT_DEBUG("qtaguid: ctrl_tag(%s): done.\n", input);
+	return res;
+}
+
+static int ctrl_cmd_untag(const char *input)
+{
+	char cmd;
+	int sock_fd = 0;
+	struct socket *el_socket;
+	int res, argc;
+	struct sock_tag *sock_tag_entry;
+	struct tag_ref *tag_ref_entry;
+	struct uid_tag_data *utd_entry;
+	struct proc_qtu_data *pqd_entry;
+
+	argc = sscanf(input, "%c %d", &cmd, &sock_fd);
+	CT_DEBUG("qtaguid: ctrl_untag(%s): argc=%d cmd=%c sock_fd=%d\n",
+		 input, argc, cmd, sock_fd);
+	if (argc < 2) {
+		res = -EINVAL;
+		goto err;
+	}
+	el_socket = sockfd_lookup(sock_fd, &res);  /* This locks the file */
+	if (!el_socket) {
+		pr_info("qtaguid: ctrl_untag(%s): failed to lookup"
+			" sock_fd=%d err=%d\n", input, sock_fd, res);
+		goto err;
+	}
+	CT_DEBUG("qtaguid: ctrl_untag(%s): socket->...->f_count=%ld ->sk=%p\n",
+		 input, atomic_long_read(&el_socket->file->f_count),
+		 el_socket->sk);
+	spin_lock_bh(&sock_tag_list_lock);
+	sock_tag_entry = get_sock_stat_nl(el_socket->sk);
+	if (!sock_tag_entry) {
+		spin_unlock_bh(&sock_tag_list_lock);
+		res = -EINVAL;
+		goto err_put;
+	}
+	/*
+	 * The socket already belongs to the current process
+	 * so it can do whatever it wants to it.
+	 */
+	rb_erase(&sock_tag_entry->sock_node, &sock_tag_tree);
+
+	tag_ref_entry = lookup_tag_ref(sock_tag_entry->tag, &utd_entry);
+	BUG_ON(!tag_ref_entry);
+	BUG_ON(tag_ref_entry->num_sock_tags <= 0);
+	spin_lock_bh(&uid_tag_data_tree_lock);
+	pqd_entry = proc_qtu_data_tree_search(
+		&proc_qtu_data_tree, current->tgid);
+	/*
+	 * TODO: remove if, and start failing.
+	 * At first, we want to catch user-space code that is not
+	 * opening the /dev/xt_qtaguid.
+	 */
+	if (IS_ERR_OR_NULL(pqd_entry))
+		pr_warn_once("qtaguid: %s(): "
+			     "User space forgot to open /dev/xt_qtaguid? "
+			     "pid=%u tgid=%u uid=%u\n", __func__,
+			     current->pid, current->tgid, current_fsuid());
+	else
+		list_del(&sock_tag_entry->list);
+	spin_unlock_bh(&uid_tag_data_tree_lock);
+	/*
+	 * We don't free tag_ref from the utd_entry here,
+	 * only during a cmd_delete().
+	 */
+	tag_ref_entry->num_sock_tags--;
+	spin_unlock_bh(&sock_tag_list_lock);
+	/*
+	 * Release the sock_fd that was grabbed at tag time,
+	 * and once more for the sockfd_lookup() here.
+	 */
+	sockfd_put(sock_tag_entry->socket);
+	CT_DEBUG("qtaguid: ctrl_untag(%s): done. st@%p ...->f_count=%ld\n",
+		 input, sock_tag_entry,
+		 atomic_long_read(&el_socket->file->f_count) - 1);
+	sockfd_put(el_socket);
+
+	kfree(sock_tag_entry);
+	atomic64_inc(&qtu_events.sockets_untagged);
+
+	return 0;
+
+err_put:
+	CT_DEBUG("qtaguid: ctrl_untag(%s): done. socket->...->f_count=%ld\n",
+		 input, atomic_long_read(&el_socket->file->f_count) - 1);
+	/* Release the sock_fd that was grabbed by sockfd_lookup(). */
+	sockfd_put(el_socket);
+	return res;
+
+err:
+	CT_DEBUG("qtaguid: ctrl_untag(%s): done.\n", input);
+	return res;
+}
+
+static int qtaguid_ctrl_parse(const char *input, int count)
+{
+	char cmd;
+	int res;
+
+	cmd = input[0];
+	/* Collect params for commands */
+	switch (cmd) {
+	case 'd':
+		res = ctrl_cmd_delete(input);
+		break;
+
+	case 's':
+		res = ctrl_cmd_counter_set(input);
+		break;
+
+	case 't':
+		res = ctrl_cmd_tag(input);
+		break;
+
+	case 'u':
+		res = ctrl_cmd_untag(input);
+		break;
+
+	default:
+		res = -EINVAL;
+		goto err;
+	}
+	if (!res)
+		res = count;
+err:
+	CT_DEBUG("qtaguid: ctrl(%s): res=%d\n", input, res);
+	return res;
+}
+
+#define MAX_QTAGUID_CTRL_INPUT_LEN 255
+static int qtaguid_ctrl_proc_write(struct file *file, const char __user *buffer,
+			unsigned long count, void *data)
+{
+	char input_buf[MAX_QTAGUID_CTRL_INPUT_LEN];
+
+	if (unlikely(module_passive))
+		return count;
+
+	if (count >= MAX_QTAGUID_CTRL_INPUT_LEN)
+		return -EINVAL;
+
+	if (copy_from_user(input_buf, buffer, count))
+		return -EFAULT;
+
+	input_buf[count] = '\0';
+	return qtaguid_ctrl_parse(input_buf, count);
+}
+
+struct proc_print_info {
+	char *outp;
+	char **num_items_returned;
+	struct iface_stat *iface_entry;
+	struct tag_stat *ts_entry;
+	int item_index;
+	int items_to_skip;
+	int char_count;
+};
+
+static int pp_stats_line(struct proc_print_info *ppi, int cnt_set)
+{
+	int len;
+	struct data_counters *cnts;
+
+	if (!ppi->item_index) {
+		if (ppi->item_index++ < ppi->items_to_skip)
+			return 0;
+		len = snprintf(ppi->outp, ppi->char_count,
+			       "idx iface acct_tag_hex uid_tag_int cnt_set "
+			       "rx_bytes rx_packets "
+			       "tx_bytes tx_packets "
+			       "rx_tcp_bytes rx_tcp_packets "
+			       "rx_udp_bytes rx_udp_packets "
+			       "rx_other_bytes rx_other_packets "
+			       "tx_tcp_bytes tx_tcp_packets "
+			       "tx_udp_bytes tx_udp_packets "
+			       "tx_other_bytes tx_other_packets\n");
+	} else {
+		tag_t tag = ppi->ts_entry->tn.tag;
+		uid_t stat_uid = get_uid_from_tag(tag);
+
+		if (!can_read_other_uid_stats(stat_uid)) {
+			CT_DEBUG("qtaguid: stats line: "
+				 "%s 0x%llx %u: insufficient priv "
+				 "from pid=%u tgid=%u uid=%u\n",
+				 ppi->iface_entry->ifname,
+				 get_atag_from_tag(tag), stat_uid,
+				 current->pid, current->tgid, current_fsuid());
+			return 0;
+		}
+		if (ppi->item_index++ < ppi->items_to_skip)
+			return 0;
+		cnts = &ppi->ts_entry->counters;
+		len = snprintf(
+			ppi->outp, ppi->char_count,
+			"%d %s 0x%llx %u %u "
+			"%llu %llu "
+			"%llu %llu "
+			"%llu %llu "
+			"%llu %llu "
+			"%llu %llu "
+			"%llu %llu "
+			"%llu %llu "
+			"%llu %llu\n",
+			ppi->item_index,
+			ppi->iface_entry->ifname,
+			get_atag_from_tag(tag),
+			stat_uid,
+			cnt_set,
+			dc_sum_bytes(cnts, cnt_set, IFS_RX),
+			dc_sum_packets(cnts, cnt_set, IFS_RX),
+			dc_sum_bytes(cnts, cnt_set, IFS_TX),
+			dc_sum_packets(cnts, cnt_set, IFS_TX),
+			cnts->bpc[cnt_set][IFS_RX][IFS_TCP].bytes,
+			cnts->bpc[cnt_set][IFS_RX][IFS_TCP].packets,
+			cnts->bpc[cnt_set][IFS_RX][IFS_UDP].bytes,
+			cnts->bpc[cnt_set][IFS_RX][IFS_UDP].packets,
+			cnts->bpc[cnt_set][IFS_RX][IFS_PROTO_OTHER].bytes,
+			cnts->bpc[cnt_set][IFS_RX][IFS_PROTO_OTHER].packets,
+			cnts->bpc[cnt_set][IFS_TX][IFS_TCP].bytes,
+			cnts->bpc[cnt_set][IFS_TX][IFS_TCP].packets,
+			cnts->bpc[cnt_set][IFS_TX][IFS_UDP].bytes,
+			cnts->bpc[cnt_set][IFS_TX][IFS_UDP].packets,
+			cnts->bpc[cnt_set][IFS_TX][IFS_PROTO_OTHER].bytes,
+			cnts->bpc[cnt_set][IFS_TX][IFS_PROTO_OTHER].packets);
+	}
+	return len;
+}
+
+static bool pp_sets(struct proc_print_info *ppi)
+{
+	int len;
+	int counter_set;
+	for (counter_set = 0; counter_set < IFS_MAX_COUNTER_SETS;
+	     counter_set++) {
+		len = pp_stats_line(ppi, counter_set);
+		if (len >= ppi->char_count) {
+			*ppi->outp = '\0';
+			return false;
+		}
+		if (len) {
+			ppi->outp += len;
+			ppi->char_count -= len;
+			(*ppi->num_items_returned)++;
+		}
+	}
+	return true;
+}
+
+/*
+ * Procfs reader to get all tag stats using style "1)" as described in
+ * fs/proc/generic.c
+ * Groups all protocols tx/rx bytes.
+ */
+static int qtaguid_stats_proc_read(char *page, char **num_items_returned,
+				off_t items_to_skip, int char_count, int *eof,
+				void *data)
+{
+	struct proc_print_info ppi;
+	int len;
+
+	ppi.outp = page;
+	ppi.item_index = 0;
+	ppi.char_count = char_count;
+	ppi.num_items_returned = num_items_returned;
+	ppi.items_to_skip = items_to_skip;
+
+	if (unlikely(module_passive)) {
+		len = pp_stats_line(&ppi, 0);
+		/* The header should always be shorter than the buffer. */
+		BUG_ON(len >= ppi.char_count);
+		(*num_items_returned)++;
+		*eof = 1;
+		return len;
+	}
+
+	CT_DEBUG("qtaguid:proc stats page=%p *num_items_returned=%p off=%ld "
+		"char_count=%d *eof=%d\n", page, *num_items_returned,
+		items_to_skip, char_count, *eof);
+
+	if (*eof)
+		return 0;
+
+	/* The idx is there to help debug when things go belly up. */
+	len = pp_stats_line(&ppi, 0);
+	/* Don't advance the outp unless the whole line was printed */
+	if (len >= ppi.char_count) {
+		*ppi.outp = '\0';
+		return ppi.outp - page;
+	}
+	if (len) {
+		ppi.outp += len;
+		ppi.char_count -= len;
+		(*num_items_returned)++;
+	}
+
+	spin_lock_bh(&iface_stat_list_lock);
+	list_for_each_entry(ppi.iface_entry, &iface_stat_list, list) {
+		struct rb_node *node;
+		spin_lock_bh(&ppi.iface_entry->tag_stat_list_lock);
+		for (node = rb_first(&ppi.iface_entry->tag_stat_tree);
+		     node;
+		     node = rb_next(node)) {
+			ppi.ts_entry = rb_entry(node, struct tag_stat, tn.node);
+			if (!pp_sets(&ppi)) {
+				spin_unlock_bh(
+					&ppi.iface_entry->tag_stat_list_lock);
+				spin_unlock_bh(&iface_stat_list_lock);
+				return ppi.outp - page;
+			}
+		}
+		spin_unlock_bh(&ppi.iface_entry->tag_stat_list_lock);
+	}
+	spin_unlock_bh(&iface_stat_list_lock);
+
+	*eof = 1;
+	return ppi.outp - page;
+}
+
+/*------------------------------------------*/
+static int qtudev_open(struct inode *inode, struct file *file)
+{
+	struct uid_tag_data *utd_entry;
+	struct proc_qtu_data  *pqd_entry;
+	struct proc_qtu_data  *new_pqd_entry;
+	int res;
+	bool utd_entry_found;
+
+	if (unlikely(qtu_proc_handling_passive))
+		return 0;
+
+	DR_DEBUG("qtaguid: qtudev_open(): pid=%u tgid=%u uid=%u\n",
+		 current->pid, current->tgid, current_fsuid());
+
+	spin_lock_bh(&uid_tag_data_tree_lock);
+
+	/* Look for existing uid data, or alloc one. */
+	utd_entry = get_uid_data(current_fsuid(), &utd_entry_found);
+	if (IS_ERR_OR_NULL(utd_entry)) {
+		res = PTR_ERR(utd_entry);
+		goto err;
+	}
+
+	/* Look for existing PID based proc_data */
+	pqd_entry = proc_qtu_data_tree_search(&proc_qtu_data_tree,
+					      current->tgid);
+	if (pqd_entry) {
+		pr_err("qtaguid: qtudev_open(): %u/%u %u "
+		       "%s already opened\n",
+		       current->pid, current->tgid, current_fsuid(),
+		       QTU_DEV_NAME);
+		res = -EBUSY;
+		goto err_unlock_free_utd;
+	}
+
+	new_pqd_entry = kzalloc(sizeof(*new_pqd_entry), GFP_ATOMIC);
+	if (!new_pqd_entry) {
+		pr_err("qtaguid: qtudev_open(): %u/%u %u: "
+		       "proc data alloc failed\n",
+		       current->pid, current->tgid, current_fsuid());
+		res = -ENOMEM;
+		goto err_unlock_free_utd;
+	}
+	new_pqd_entry->pid = current->tgid;
+	INIT_LIST_HEAD(&new_pqd_entry->sock_tag_list);
+	new_pqd_entry->parent_tag_data = utd_entry;
+	utd_entry->num_pqd++;
+
+	proc_qtu_data_tree_insert(new_pqd_entry,
+				  &proc_qtu_data_tree);
+
+	spin_unlock_bh(&uid_tag_data_tree_lock);
+	DR_DEBUG("qtaguid: tracking data for uid=%u in pqd=%p\n",
+		 current_fsuid(), new_pqd_entry);
+	file->private_data = new_pqd_entry;
+	return 0;
+
+err_unlock_free_utd:
+	if (!utd_entry_found) {
+		rb_erase(&utd_entry->node, &uid_tag_data_tree);
+		kfree(utd_entry);
+	}
+	spin_unlock_bh(&uid_tag_data_tree_lock);
+err:
+	return res;
+}
+
+static int qtudev_release(struct inode *inode, struct file *file)
+{
+	struct proc_qtu_data  *pqd_entry = file->private_data;
+	struct uid_tag_data  *utd_entry = pqd_entry->parent_tag_data;
+	struct sock_tag *st_entry;
+	struct rb_root st_to_free_tree = RB_ROOT;
+	struct list_head *entry, *next;
+	struct tag_ref *tr;
+
+	if (unlikely(qtu_proc_handling_passive))
+		return 0;
+
+	/*
+	 * Do not trust the current->pid, it might just be a kworker cleaning
+	 * up after a dead proc.
+	 */
+	DR_DEBUG("qtaguid: qtudev_release(): "
+		 "pid=%u tgid=%u uid=%u "
+		 "pqd_entry=%p->pid=%u utd_entry=%p->active_tags=%d\n",
+		 current->pid, current->tgid, pqd_entry->parent_tag_data->uid,
+		 pqd_entry, pqd_entry->pid, utd_entry,
+		 utd_entry->num_active_tags);
+
+	spin_lock_bh(&sock_tag_list_lock);
+	spin_lock_bh(&uid_tag_data_tree_lock);
+
+	list_for_each_safe(entry, next, &pqd_entry->sock_tag_list) {
+		st_entry = list_entry(entry, struct sock_tag, list);
+		DR_DEBUG("qtaguid: %s(): "
+			 "erase sock_tag=%p->sk=%p pid=%u tgid=%u uid=%u\n",
+			 __func__,
+			 st_entry, st_entry->sk,
+			 current->pid, current->tgid,
+			 pqd_entry->parent_tag_data->uid);
+
+		utd_entry = uid_tag_data_tree_search(
+			&uid_tag_data_tree,
+			get_uid_from_tag(st_entry->tag));
+		BUG_ON(IS_ERR_OR_NULL(utd_entry));
+		DR_DEBUG("qtaguid: %s(): "
+			 "looking for tag=0x%llx in utd_entry=%p\n", __func__,
+			 st_entry->tag, utd_entry);
+		tr = tag_ref_tree_search(&utd_entry->tag_ref_tree,
+					 st_entry->tag);
+		BUG_ON(!tr);
+		BUG_ON(tr->num_sock_tags <= 0);
+		tr->num_sock_tags--;
+		free_tag_ref_from_utd_entry(tr, utd_entry);
+
+		rb_erase(&st_entry->sock_node, &sock_tag_tree);
+		list_del(&st_entry->list);
+		/* Can't sockfd_put() within spinlock, do it later. */
+		sock_tag_tree_insert(st_entry, &st_to_free_tree);
+
+		/*
+		 * Try to free the utd_entry if no other proc_qtu_data is
+		 * using it (num_pqd is 0) and it doesn't have active tags
+		 * (num_active_tags is 0).
+		 */
+		put_utd_entry(utd_entry);
+	}
+
+	rb_erase(&pqd_entry->node, &proc_qtu_data_tree);
+	BUG_ON(pqd_entry->parent_tag_data->num_pqd < 1);
+	pqd_entry->parent_tag_data->num_pqd--;
+	put_utd_entry(pqd_entry->parent_tag_data);
+	kfree(pqd_entry);
+	file->private_data = NULL;
+
+	spin_unlock_bh(&uid_tag_data_tree_lock);
+	spin_unlock_bh(&sock_tag_list_lock);
+
+
+	sock_tag_tree_erase(&st_to_free_tree);
+
+	prdebug_full_state(0, "%s(): pid=%u tgid=%u", __func__,
+			   current->pid, current->tgid);
+	return 0;
+}
+
+/*------------------------------------------*/
+static const struct file_operations qtudev_fops = {
+	.owner = THIS_MODULE,
+	.open = qtudev_open,
+	.release = qtudev_release,
+};
+
+static struct miscdevice qtu_device = {
+	.minor = MISC_DYNAMIC_MINOR,
+	.name = QTU_DEV_NAME,
+	.fops = &qtudev_fops,
+	/* How sad it doesn't allow for defaults: .mode = S_IRUGO | S_IWUSR */
+};
+
+/*------------------------------------------*/
+static int __init qtaguid_proc_register(struct proc_dir_entry **res_procdir)
+{
+	int ret;
+	*res_procdir = proc_mkdir(module_procdirname, init_net.proc_net);
+	if (!*res_procdir) {
+		pr_err("qtaguid: failed to create proc/.../xt_qtaguid\n");
+		ret = -ENOMEM;
+		goto no_dir;
+	}
+
+	xt_qtaguid_ctrl_file = create_proc_entry("ctrl", proc_ctrl_perms,
+						*res_procdir);
+	if (!xt_qtaguid_ctrl_file) {
+		pr_err("qtaguid: failed to create xt_qtaguid/ctrl "
+			" file\n");
+		ret = -ENOMEM;
+		goto no_ctrl_entry;
+	}
+	xt_qtaguid_ctrl_file->read_proc = qtaguid_ctrl_proc_read;
+	xt_qtaguid_ctrl_file->write_proc = qtaguid_ctrl_proc_write;
+
+	xt_qtaguid_stats_file = create_proc_entry("stats", proc_stats_perms,
+						*res_procdir);
+	if (!xt_qtaguid_stats_file) {
+		pr_err("qtaguid: failed to create xt_qtaguid/stats "
+			"file\n");
+		ret = -ENOMEM;
+		goto no_stats_entry;
+	}
+	xt_qtaguid_stats_file->read_proc = qtaguid_stats_proc_read;
+	/*
+	 * TODO: add support counter hacking
+	 * xt_qtaguid_stats_file->write_proc = qtaguid_stats_proc_write;
+	 */
+	return 0;
+
+no_stats_entry:
+	remove_proc_entry("ctrl", *res_procdir);
+no_ctrl_entry:
+	remove_proc_entry("xt_qtaguid", NULL);
+no_dir:
+	return ret;
+}
+
+static struct xt_match qtaguid_mt_reg __read_mostly = {
+	/*
+	 * This module masquerades as the "owner" module so that iptables
+	 * tools can deal with it.
+	 */
+	.name       = "owner",
+	.revision   = 1,
+	.family     = NFPROTO_UNSPEC,
+	.match      = qtaguid_mt,
+	.matchsize  = sizeof(struct xt_qtaguid_match_info),
+	.me         = THIS_MODULE,
+};
+
+static int __init qtaguid_mt_init(void)
+{
+	if (qtaguid_proc_register(&xt_qtaguid_procdir)
+	    || iface_stat_init(xt_qtaguid_procdir)
+	    || xt_register_match(&qtaguid_mt_reg)
+	    || misc_register(&qtu_device))
+		return -1;
+	return 0;
+}
+
+/*
+ * TODO: allow unloading of the module.
+ * For now stats are permanent.
+ * Kconfig forces'y/n' and never an 'm'.
+ */
+
+module_init(qtaguid_mt_init);
+MODULE_AUTHOR("jpa <jpa@google.com>");
+MODULE_DESCRIPTION("Xtables: socket owner+tag matching and associated stats");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("ipt_owner");
+MODULE_ALIAS("ip6t_owner");
+MODULE_ALIAS("ipt_qtaguid");
+MODULE_ALIAS("ip6t_qtaguid");