ANDROID: netfilter: xt_quota2: adding the original quota2 from xtables-addons

The original xt_quota in the kernel is plain broken:
  - counts quota at a per CPU level
    (was written back when ubiquitous SMP was just a dream)
  - provides no way to count across IPV4/IPV6.

This patch is the original unaltered code from:
  http://sourceforge.net/projects/xtables-addons

  at commit e84391ce665cef046967f796dd91026851d6bbf3

Bug: 120445421
Change-Id: I19d49858840effee9ecf6cff03c23b45a97efdeb
Signed-off-by: JP Abgrall <jpa@google.com>
[astrachan: Folded 4d33aa305871 ("netfilter: xt_quota2: fixup the quota2,
            and enable.") into this patch]
Signed-off-by: Alistair Strachan <astrachan@google.com>

include/linux/netfilter/xt_quota2.h

@@ -0,0 +1,25 @@
+#ifndef _XT_QUOTA_H
+#define _XT_QUOTA_H
+
+enum xt_quota_flags {
+	XT_QUOTA_INVERT    = 1 << 0,
+	XT_QUOTA_GROW      = 1 << 1,
+	XT_QUOTA_PACKET    = 1 << 2,
+	XT_QUOTA_NO_CHANGE = 1 << 3,
+	XT_QUOTA_MASK      = 0x0F,
+};
+
+struct xt_quota_counter;
+
+struct xt_quota_mtinfo2 {
+	char name[15];
+	u_int8_t flags;
+
+	/* Comparison-invariant */
+	aligned_u64 quota;
+
+	/* Used internally by the kernel */
+	struct xt_quota_counter *master __attribute__((aligned(8)));
+};
+
+#endif /* _XT_QUOTA_H */

net/netfilter/Kconfig

@@ -1460,6 +1460,29 @@ config NETFILTER_XT_MATCH_QUOTA
 	  If you want to compile it as a module, say M here and read
 	  <file:Documentation/kbuild/modules.txt>.  If unsure, say `N'.
 
+config NETFILTER_XT_MATCH_QUOTA2
+	tristate '"quota2" match support'
+	depends on NETFILTER_ADVANCED
+	help
+	  This option adds a `quota2' match, which allows to match on a
+	  byte counter correctly and not per CPU.
+	  It allows naming the quotas.
+	  This is based on http://xtables-addons.git.sourceforge.net
+
+	  If you want to compile it as a module, say M here and read
+	  <file:Documentation/kbuild/modules.txt>.  If unsure, say `N'.
+
+config NETFILTER_XT_MATCH_QUOTA2_LOG
+	bool '"quota2" Netfilter LOG support'
+	depends on NETFILTER_XT_MATCH_QUOTA2
+	default n
+	help
+	  This option allows `quota2' to log ONCE when a quota limit
+	  is passed. It logs via NETLINK using the NETLINK_NFLOG family.
+	  It logs similarly to how ipt_ULOG would without data.
+
+	  If unsure, say `N'.
+
 config NETFILTER_XT_MATCH_RATEEST
 	tristate '"rateest" match support'
 	depends on NETFILTER_ADVANCED

net/netfilter/Makefile

@@ -191,6 +191,7 @@ obj-$(CONFIG_NETFILTER_XT_MATCH_PHYSDEV) += xt_physdev.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_PKTTYPE) += xt_pkttype.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_POLICY) += xt_policy.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_QUOTA) += xt_quota.o
+obj-$(CONFIG_NETFILTER_XT_MATCH_QUOTA2) += xt_quota2.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_RATEEST) += xt_rateest.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_REALM) += xt_realm.o
 obj-$(CONFIG_NETFILTER_XT_MATCH_RECENT) += xt_recent.o

net/netfilter/xt_quota2.c

@@ -0,0 +1,401 @@
+/*
+ * xt_quota2 - enhanced xt_quota that can count upwards and in packets
+ * as a minimal accounting match.
+ * by Jan Engelhardt <jengelh@medozas.de>, 2008
+ *
+ * Originally based on xt_quota.c:
+ * 	netfilter module to enforce network quotas
+ * 	Sam Johnston <samj@samj.net>
+ *
+ *	This program is free software; you can redistribute it and/or modify
+ *	it under the terms of the GNU General Public License; either
+ *	version 2 of the License, as published by the Free Software Foundation.
+ */
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/skbuff.h>
+#include <linux/spinlock.h>
+#include <asm/atomic.h>
+#include <net/netlink.h>
+
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter/xt_quota2.h>
+
+#ifdef CONFIG_NETFILTER_XT_MATCH_QUOTA2_LOG
+/* For compatibility, these definitions are copied from the
+ * deprecated header file <linux/netfilter_ipv4/ipt_ULOG.h> */
+#define ULOG_MAC_LEN	80
+#define ULOG_PREFIX_LEN	32
+
+/* Format of the ULOG packets passed through netlink */
+typedef struct ulog_packet_msg {
+	unsigned long mark;
+	long timestamp_sec;
+	long timestamp_usec;
+	unsigned int hook;
+	char indev_name[IFNAMSIZ];
+	char outdev_name[IFNAMSIZ];
+	size_t data_len;
+	char prefix[ULOG_PREFIX_LEN];
+	unsigned char mac_len;
+	unsigned char mac[ULOG_MAC_LEN];
+	unsigned char payload[0];
+} ulog_packet_msg_t;
+#endif
+
+/**
+ * @lock:	lock to protect quota writers from each other
+ */
+struct xt_quota_counter {
+	u_int64_t quota;
+	spinlock_t lock;
+	struct list_head list;
+	atomic_t ref;
+	char name[sizeof(((struct xt_quota_mtinfo2 *)NULL)->name)];
+	struct proc_dir_entry *procfs_entry;
+};
+
+#ifdef CONFIG_NETFILTER_XT_MATCH_QUOTA2_LOG
+/* Harald's favorite number +1 :D From ipt_ULOG.C */
+static int qlog_nl_event = 112;
+module_param_named(event_num, qlog_nl_event, uint, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(event_num,
+		 "Event number for NETLINK_NFLOG message. 0 disables log."
+		 "111 is what ipt_ULOG uses.");
+static struct sock *nflognl;
+#endif
+
+static LIST_HEAD(counter_list);
+static DEFINE_SPINLOCK(counter_list_lock);
+
+static struct proc_dir_entry *proc_xt_quota;
+static unsigned int quota_list_perms = S_IRUGO | S_IWUSR;
+static kuid_t quota_list_uid = KUIDT_INIT(0);
+static kgid_t quota_list_gid = KGIDT_INIT(0);
+module_param_named(perms, quota_list_perms, uint, S_IRUGO | S_IWUSR);
+
+#ifdef CONFIG_NETFILTER_XT_MATCH_QUOTA2_LOG
+static void quota2_log(unsigned int hooknum,
+		       const struct sk_buff *skb,
+		       const struct net_device *in,
+		       const struct net_device *out,
+		       const char *prefix)
+{
+	ulog_packet_msg_t *pm;
+	struct sk_buff *log_skb;
+	size_t size;
+	struct nlmsghdr *nlh;
+
+	if (!qlog_nl_event)
+		return;
+
+	size = NLMSG_SPACE(sizeof(*pm));
+	size = max(size, (size_t)NLMSG_GOODSIZE);
+	log_skb = alloc_skb(size, GFP_ATOMIC);
+	if (!log_skb) {
+		pr_err("xt_quota2: cannot alloc skb for logging\n");
+		return;
+	}
+
+	nlh = nlmsg_put(log_skb, /*pid*/0, /*seq*/0, qlog_nl_event,
+			sizeof(*pm), 0);
+	if (!nlh) {
+		pr_err("xt_quota2: nlmsg_put failed\n");
+		kfree_skb(log_skb);
+		return;
+	}
+	pm = nlmsg_data(nlh);
+	if (skb->tstamp == 0)
+		__net_timestamp((struct sk_buff *)skb);
+	pm->data_len = 0;
+	pm->hook = hooknum;
+	if (prefix != NULL)
+		strlcpy(pm->prefix, prefix, sizeof(pm->prefix));
+	else
+		*(pm->prefix) = '\0';
+	if (in)
+		strlcpy(pm->indev_name, in->name, sizeof(pm->indev_name));
+	else
+		pm->indev_name[0] = '\0';
+
+	if (out)
+		strlcpy(pm->outdev_name, out->name, sizeof(pm->outdev_name));
+	else
+		pm->outdev_name[0] = '\0';
+
+	NETLINK_CB(log_skb).dst_group = 1;
+	pr_debug("throwing 1 packets to netlink group 1\n");
+	netlink_broadcast(nflognl, log_skb, 0, 1, GFP_ATOMIC);
+}
+#else
+static void quota2_log(unsigned int hooknum,
+		       const struct sk_buff *skb,
+		       const struct net_device *in,
+		       const struct net_device *out,
+		       const char *prefix)
+{
+}
+#endif  /* if+else CONFIG_NETFILTER_XT_MATCH_QUOTA2_LOG */
+
+static ssize_t quota_proc_read(struct file *file, char __user *buf,
+			   size_t size, loff_t *ppos)
+{
+	struct xt_quota_counter *e = PDE_DATA(file_inode(file));
+	char tmp[24];
+	size_t tmp_size;
+
+	spin_lock_bh(&e->lock);
+	tmp_size = scnprintf(tmp, sizeof(tmp), "%llu\n", e->quota);
+	spin_unlock_bh(&e->lock);
+	return simple_read_from_buffer(buf, size, ppos, tmp, tmp_size);
+}
+
+static ssize_t quota_proc_write(struct file *file, const char __user *input,
+                            size_t size, loff_t *ppos)
+{
+	struct xt_quota_counter *e = PDE_DATA(file_inode(file));
+	char buf[sizeof("18446744073709551616")];
+
+	if (size > sizeof(buf))
+		size = sizeof(buf);
+	if (copy_from_user(buf, input, size) != 0)
+		return -EFAULT;
+	buf[sizeof(buf)-1] = '\0';
+
+	spin_lock_bh(&e->lock);
+	e->quota = simple_strtoull(buf, NULL, 0);
+	spin_unlock_bh(&e->lock);
+	return size;
+}
+
+static const struct file_operations q2_counter_fops = {
+	.read		= quota_proc_read,
+	.write		= quota_proc_write,
+	.llseek		= default_llseek,
+};
+
+static struct xt_quota_counter *
+q2_new_counter(const struct xt_quota_mtinfo2 *q, bool anon)
+{
+	struct xt_quota_counter *e;
+	unsigned int size;
+
+	/* Do not need all the procfs things for anonymous counters. */
+	size = anon ? offsetof(typeof(*e), list) : sizeof(*e);
+	e = kmalloc(size, GFP_KERNEL);
+	if (e == NULL)
+		return NULL;
+
+	e->quota = q->quota;
+	spin_lock_init(&e->lock);
+	if (!anon) {
+		INIT_LIST_HEAD(&e->list);
+		atomic_set(&e->ref, 1);
+		strlcpy(e->name, q->name, sizeof(e->name));
+	}
+	return e;
+}
+
+/**
+ * q2_get_counter - get ref to counter or create new
+ * @name:	name of counter
+ */
+static struct xt_quota_counter *
+q2_get_counter(const struct xt_quota_mtinfo2 *q)
+{
+	struct proc_dir_entry *p;
+	struct xt_quota_counter *e = NULL;
+	struct xt_quota_counter *new_e;
+
+	if (*q->name == '\0')
+		return q2_new_counter(q, true);
+
+	/* No need to hold a lock while getting a new counter */
+	new_e = q2_new_counter(q, false);
+	if (new_e == NULL)
+		goto out;
+
+	spin_lock_bh(&counter_list_lock);
+	list_for_each_entry(e, &counter_list, list)
+		if (strcmp(e->name, q->name) == 0) {
+			atomic_inc(&e->ref);
+			spin_unlock_bh(&counter_list_lock);
+			kfree(new_e);
+			pr_debug("xt_quota2: old counter name=%s", e->name);
+			return e;
+		}
+	e = new_e;
+	pr_debug("xt_quota2: new_counter name=%s", e->name);
+	list_add_tail(&e->list, &counter_list);
+	/* The entry having a refcount of 1 is not directly destructible.
+	 * This func has not yet returned the new entry, thus iptables
+	 * has not references for destroying this entry.
+	 * For another rule to try to destroy it, it would 1st need for this
+	 * func* to be re-invoked, acquire a new ref for the same named quota.
+	 * Nobody will access the e->procfs_entry either.
+	 * So release the lock. */
+	spin_unlock_bh(&counter_list_lock);
+
+	/* create_proc_entry() is not spin_lock happy */
+	p = e->procfs_entry = proc_create_data(e->name, quota_list_perms,
+	                      proc_xt_quota, &q2_counter_fops, e);
+
+	if (IS_ERR_OR_NULL(p)) {
+		spin_lock_bh(&counter_list_lock);
+		list_del(&e->list);
+		spin_unlock_bh(&counter_list_lock);
+		goto out;
+	}
+	proc_set_user(p, quota_list_uid, quota_list_gid);
+	return e;
+
+ out:
+	kfree(e);
+	return NULL;
+}
+
+static int quota_mt2_check(const struct xt_mtchk_param *par)
+{
+	struct xt_quota_mtinfo2 *q = par->matchinfo;
+
+	pr_debug("xt_quota2: check() flags=0x%04x", q->flags);
+
+	if (q->flags & ~XT_QUOTA_MASK)
+		return -EINVAL;
+
+	q->name[sizeof(q->name)-1] = '\0';
+	if (*q->name == '.' || strchr(q->name, '/') != NULL) {
+		printk(KERN_ERR "xt_quota.3: illegal name\n");
+		return -EINVAL;
+	}
+
+	q->master = q2_get_counter(q);
+	if (q->master == NULL) {
+		printk(KERN_ERR "xt_quota.3: memory alloc failure\n");
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+static void quota_mt2_destroy(const struct xt_mtdtor_param *par)
+{
+	struct xt_quota_mtinfo2 *q = par->matchinfo;
+	struct xt_quota_counter *e = q->master;
+
+	if (*q->name == '\0') {
+		kfree(e);
+		return;
+	}
+
+	spin_lock_bh(&counter_list_lock);
+	if (!atomic_dec_and_test(&e->ref)) {
+		spin_unlock_bh(&counter_list_lock);
+		return;
+	}
+
+	list_del(&e->list);
+	remove_proc_entry(e->name, proc_xt_quota);
+	spin_unlock_bh(&counter_list_lock);
+	kfree(e);
+}
+
+static bool
+quota_mt2(const struct sk_buff *skb, struct xt_action_param *par)
+{
+	struct xt_quota_mtinfo2 *q = (void *)par->matchinfo;
+	struct xt_quota_counter *e = q->master;
+	bool ret = q->flags & XT_QUOTA_INVERT;
+
+	spin_lock_bh(&e->lock);
+	if (q->flags & XT_QUOTA_GROW) {
+		/*
+		 * While no_change is pointless in "grow" mode, we will
+		 * implement it here simply to have a consistent behavior.
+		 */
+		if (!(q->flags & XT_QUOTA_NO_CHANGE)) {
+			e->quota += (q->flags & XT_QUOTA_PACKET) ? 1 : skb->len;
+		}
+		ret = true;
+	} else {
+		if (e->quota >= skb->len) {
+			if (!(q->flags & XT_QUOTA_NO_CHANGE))
+				e->quota -= (q->flags & XT_QUOTA_PACKET) ? 1 : skb->len;
+			ret = !ret;
+		} else {
+			/* We are transitioning, log that fact. */
+			if (e->quota) {
+				quota2_log(xt_hooknum(par),
+					   skb,
+					   xt_in(par),
+					   xt_out(par),
+					   q->name);
+			}
+			/* we do not allow even small packets from now on */
+			e->quota = 0;
+		}
+	}
+	spin_unlock_bh(&e->lock);
+	return ret;
+}
+
+static struct xt_match quota_mt2_reg[] __read_mostly = {
+	{
+		.name       = "quota2",
+		.revision   = 3,
+		.family     = NFPROTO_IPV4,
+		.checkentry = quota_mt2_check,
+		.match      = quota_mt2,
+		.destroy    = quota_mt2_destroy,
+		.matchsize  = sizeof(struct xt_quota_mtinfo2),
+		.me         = THIS_MODULE,
+	},
+	{
+		.name       = "quota2",
+		.revision   = 3,
+		.family     = NFPROTO_IPV6,
+		.checkentry = quota_mt2_check,
+		.match      = quota_mt2,
+		.destroy    = quota_mt2_destroy,
+		.matchsize  = sizeof(struct xt_quota_mtinfo2),
+		.me         = THIS_MODULE,
+	},
+};
+
+static int __init quota_mt2_init(void)
+{
+	int ret;
+	pr_debug("xt_quota2: init()");
+
+#ifdef CONFIG_NETFILTER_XT_MATCH_QUOTA2_LOG
+	nflognl = netlink_kernel_create(&init_net, NETLINK_NFLOG, NULL);
+	if (!nflognl)
+		return -ENOMEM;
+#endif
+
+	proc_xt_quota = proc_mkdir("xt_quota", init_net.proc_net);
+	if (proc_xt_quota == NULL)
+		return -EACCES;
+
+	ret = xt_register_matches(quota_mt2_reg, ARRAY_SIZE(quota_mt2_reg));
+	if (ret < 0)
+		remove_proc_entry("xt_quota", init_net.proc_net);
+	pr_debug("xt_quota2: init() %d", ret);
+	return ret;
+}
+
+static void __exit quota_mt2_exit(void)
+{
+	xt_unregister_matches(quota_mt2_reg, ARRAY_SIZE(quota_mt2_reg));
+	remove_proc_entry("xt_quota", init_net.proc_net);
+}
+
+module_init(quota_mt2_init);
+module_exit(quota_mt2_exit);
+MODULE_DESCRIPTION("Xtables: countdown quota match; up counter");
+MODULE_AUTHOR("Sam Johnston <samj@samj.net>");
+MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("ipt_quota2");
+MODULE_ALIAS("ip6t_quota2");