| /* |
| * 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/proc_fs.h> |
| #include <linux/skbuff.h> |
| #include <linux/spinlock.h> |
| #include <asm/atomic.h> |
| |
| #include <linux/netfilter/x_tables.h> |
| #include <linux/netfilter/xt_quota2.h> |
| |
| /** |
| * @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; |
| }; |
| |
| 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 unsigned int quota_list_uid = 0; |
| static unsigned int quota_list_gid = 0; |
| module_param_named(perms, quota_list_perms, uint, S_IRUGO | S_IWUSR); |
| module_param_named(uid, quota_list_uid, uint, S_IRUGO | S_IWUSR); |
| module_param_named(gid, quota_list_gid, uint, S_IRUGO | S_IWUSR); |
| |
| static int quota_proc_read(char *page, char **start, off_t offset, |
| int count, int *eof, void *data) |
| { |
| struct xt_quota_counter *e = data; |
| int ret; |
| |
| spin_lock_bh(&e->lock); |
| ret = snprintf(page, PAGE_SIZE, "%llu\n", e->quota); |
| spin_unlock_bh(&e->lock); |
| return ret; |
| } |
| |
| static int quota_proc_write(struct file *file, const char __user *input, |
| unsigned long size, void *data) |
| { |
| struct xt_quota_counter *e = data; |
| 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 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 = create_proc_entry(e->name, quota_list_perms, |
| proc_xt_quota); |
| |
| if (IS_ERR_OR_NULL(p)) { |
| spin_lock_bh(&counter_list_lock); |
| list_del(&e->list); |
| spin_unlock_bh(&counter_list_lock); |
| goto out; |
| } |
| p->data = e; |
| p->read_proc = quota_proc_read; |
| p->write_proc = quota_proc_write; |
| p->uid = quota_list_uid; |
| p->gid = 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 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()"); |
| |
| 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"); |