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net/netfilter/xt_quota2.c
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/* * 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 "); 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 "); 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 "); 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 ", 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; } |
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static const struct proc_ops q2_counter_fops = { .proc_read = quota_proc_read, .proc_write = quota_proc_write, .proc_lseek = default_llseek, |
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}; 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 "); return -EINVAL; } q->master = q2_get_counter(q); if (q->master == NULL) { printk(KERN_ERR "xt_quota.3: memory alloc failure "); 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); |
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spin_unlock_bh(&counter_list_lock); |
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remove_proc_entry(e->name, proc_xt_quota); |
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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; |
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int charge = (q->flags & XT_QUOTA_PACKET) ? 1 : skb->len; bool no_change = q->flags & XT_QUOTA_NO_CHANGE; |
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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. */ |
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if (!no_change) e->quota += charge; ret = true; /* note: does not respect inversion (bug??) */ |
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} else { |
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if (e->quota > charge) { if (!no_change) e->quota -= charge; |
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ret = !ret; |
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} else if (e->quota) { |
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/* We are transitioning, log that fact. */ |
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quota2_log(xt_hooknum(par), skb, xt_in(par), xt_out(par), q->name); |
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/* 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"); |