text: // SPDX-License-Identifier: GPL-2.0-only
  #include <linux/kernel.h>
  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/proc_fs.h>
  #include <linux/skbuff.h>
  #include <linux/netfilter.h>
  #include <linux/seq_file.h>
  #include <net/protocol.h>
  #include <net/netfilter/nf_log.h>
  
  #include "nf_internals.h"
  
  /* Internal logging interface, which relies on the real
     LOG target modules */
  
  #define NFLOGGER_NAME_LEN		64
  
  int sysctl_nf_log_all_netns __read_mostly;
  EXPORT_SYMBOL(sysctl_nf_log_all_netns);
  
  static struct nf_logger __rcu *loggers[NFPROTO_NUMPROTO][NF_LOG_TYPE_MAX] __read_mostly;
  static DEFINE_MUTEX(nf_log_mutex);
  
  #define nft_log_dereference(logger) \
  	rcu_dereference_protected(logger, lockdep_is_held(&nf_log_mutex))
  
  static struct nf_logger *__find_logger(int pf, const char *str_logger)
  {
  	struct nf_logger *log;
  	int i;
  
  	for (i = 0; i < NF_LOG_TYPE_MAX; i++) {
  		if (loggers[pf][i] == NULL)
  			continue;
  
  		log = nft_log_dereference(loggers[pf][i]);
  		if (!strncasecmp(str_logger, log->name, strlen(log->name)))
  			return log;
  	}
  
  	return NULL;
  }
  
  int nf_log_set(struct net *net, u_int8_t pf, const struct nf_logger *logger)
  {
  	const struct nf_logger *log;
  
  	if (pf == NFPROTO_UNSPEC || pf >= ARRAY_SIZE(net->nf.nf_loggers))
  		return -EOPNOTSUPP;
  
  	mutex_lock(&nf_log_mutex);
  	log = nft_log_dereference(net->nf.nf_loggers[pf]);
  	if (log == NULL)
  		rcu_assign_pointer(net->nf.nf_loggers[pf], logger);
  
  	mutex_unlock(&nf_log_mutex);
  
  	return 0;
  }
  EXPORT_SYMBOL(nf_log_set);
  
  void nf_log_unset(struct net *net, const struct nf_logger *logger)
  {
  	int i;
  	const struct nf_logger *log;
  
  	mutex_lock(&nf_log_mutex);
  	for (i = 0; i < NFPROTO_NUMPROTO; i++) {
  		log = nft_log_dereference(net->nf.nf_loggers[i]);
  		if (log == logger)
  			RCU_INIT_POINTER(net->nf.nf_loggers[i], NULL);
  	}
  	mutex_unlock(&nf_log_mutex);
  }
  EXPORT_SYMBOL(nf_log_unset);
  
  /* return EEXIST if the same logger is registered, 0 on success. */
  int nf_log_register(u_int8_t pf, struct nf_logger *logger)
  {
  	int i;
  	int ret = 0;
  
  	if (pf >= ARRAY_SIZE(init_net.nf.nf_loggers))
  		return -EINVAL;
  
  	mutex_lock(&nf_log_mutex);
  
  	if (pf == NFPROTO_UNSPEC) {
  		for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++) {
  			if (rcu_access_pointer(loggers[i][logger->type])) {
  				ret = -EEXIST;
  				goto unlock;
  			}
  		}
  		for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++)
  			rcu_assign_pointer(loggers[i][logger->type], logger);
  	} else {
  		if (rcu_access_pointer(loggers[pf][logger->type])) {
  			ret = -EEXIST;
  			goto unlock;
  		}
  		rcu_assign_pointer(loggers[pf][logger->type], logger);
  	}
  
  unlock:
  	mutex_unlock(&nf_log_mutex);
  	return ret;
  }
  EXPORT_SYMBOL(nf_log_register);
  
  void nf_log_unregister(struct nf_logger *logger)
  {
  	const struct nf_logger *log;
  	int i;
  
  	mutex_lock(&nf_log_mutex);
  	for (i = 0; i < NFPROTO_NUMPROTO; i++) {
  		log = nft_log_dereference(loggers[i][logger->type]);
  		if (log == logger)
  			RCU_INIT_POINTER(loggers[i][logger->type], NULL);
  	}
  	mutex_unlock(&nf_log_mutex);
  	synchronize_rcu();
  }
  EXPORT_SYMBOL(nf_log_unregister);
  
  int nf_log_bind_pf(struct net *net, u_int8_t pf,
  		   const struct nf_logger *logger)
  {
  	if (pf >= ARRAY_SIZE(net->nf.nf_loggers))
  		return -EINVAL;
  	mutex_lock(&nf_log_mutex);
  	if (__find_logger(pf, logger->name) == NULL) {
  		mutex_unlock(&nf_log_mutex);
  		return -ENOENT;
  	}
  	rcu_assign_pointer(net->nf.nf_loggers[pf], logger);
  	mutex_unlock(&nf_log_mutex);
  	return 0;
  }
  EXPORT_SYMBOL(nf_log_bind_pf);
  
  void nf_log_unbind_pf(struct net *net, u_int8_t pf)
  {
  	if (pf >= ARRAY_SIZE(net->nf.nf_loggers))
  		return;
  	mutex_lock(&nf_log_mutex);
  	RCU_INIT_POINTER(net->nf.nf_loggers[pf], NULL);
  	mutex_unlock(&nf_log_mutex);
  }
  EXPORT_SYMBOL(nf_log_unbind_pf);
  
  void nf_logger_request_module(int pf, enum nf_log_type type)
  {
  	if (loggers[pf][type] == NULL)
  		request_module("nf-logger-%u-%u", pf, type);
  }
  EXPORT_SYMBOL_GPL(nf_logger_request_module);
  
  int nf_logger_find_get(int pf, enum nf_log_type type)
  {
  	struct nf_logger *logger;
  	int ret = -ENOENT;
  
  	if (pf == NFPROTO_INET) {
  		ret = nf_logger_find_get(NFPROTO_IPV4, type);
  		if (ret < 0)
  			return ret;
  
  		ret = nf_logger_find_get(NFPROTO_IPV6, type);
  		if (ret < 0) {
  			nf_logger_put(NFPROTO_IPV4, type);
  			return ret;
  		}
  
  		return 0;
  	}
  
  	if (rcu_access_pointer(loggers[pf][type]) == NULL)
  		request_module("nf-logger-%u-%u", pf, type);
  
  	rcu_read_lock();
  	logger = rcu_dereference(loggers[pf][type]);
  	if (logger == NULL)
  		goto out;
  
  	if (try_module_get(logger->me))
  		ret = 0;
  out:
  	rcu_read_unlock();
  	return ret;
  }
  EXPORT_SYMBOL_GPL(nf_logger_find_get);
  
  void nf_logger_put(int pf, enum nf_log_type type)
  {
  	struct nf_logger *logger;
  
  	if (pf == NFPROTO_INET) {
  		nf_logger_put(NFPROTO_IPV4, type);
  		nf_logger_put(NFPROTO_IPV6, type);
  		return;
  	}
  
  	BUG_ON(loggers[pf][type] == NULL);
  
  	rcu_read_lock();
  	logger = rcu_dereference(loggers[pf][type]);
  	module_put(logger->me);
  	rcu_read_unlock();
  }
  EXPORT_SYMBOL_GPL(nf_logger_put);
  
  void nf_log_packet(struct net *net,
  		   u_int8_t pf,
  		   unsigned int hooknum,
  		   const struct sk_buff *skb,
  		   const struct net_device *in,
  		   const struct net_device *out,
  		   const struct nf_loginfo *loginfo,
  		   const char *fmt, ...)
  {
  	va_list args;
  	char prefix[NF_LOG_PREFIXLEN];
  	const struct nf_logger *logger;
  
  	rcu_read_lock();
  	if (loginfo != NULL)
  		logger = rcu_dereference(loggers[pf][loginfo->type]);
  	else
  		logger = rcu_dereference(net->nf.nf_loggers[pf]);
  
  	if (logger) {
  		va_start(args, fmt);
  		vsnprintf(prefix, sizeof(prefix), fmt, args);
  		va_end(args);
  		logger->logfn(net, pf, hooknum, skb, in, out, loginfo, prefix);
  	}
  	rcu_read_unlock();
  }
  EXPORT_SYMBOL(nf_log_packet);
  
  void nf_log_trace(struct net *net,
  		  u_int8_t pf,
  		  unsigned int hooknum,
  		  const struct sk_buff *skb,
  		  const struct net_device *in,
  		  const struct net_device *out,
  		  const struct nf_loginfo *loginfo, const char *fmt, ...)
  {
  	va_list args;
  	char prefix[NF_LOG_PREFIXLEN];
  	const struct nf_logger *logger;
  
  	rcu_read_lock();
  	logger = rcu_dereference(net->nf.nf_loggers[pf]);
  	if (logger) {
  		va_start(args, fmt);
  		vsnprintf(prefix, sizeof(prefix), fmt, args);
  		va_end(args);
  		logger->logfn(net, pf, hooknum, skb, in, out, loginfo, prefix);
  	}
  	rcu_read_unlock();
  }
  EXPORT_SYMBOL(nf_log_trace);
  
  #define S_SIZE (1024 - (sizeof(unsigned int) + 1))
  
  struct nf_log_buf {
  	unsigned int	count;
  	char		buf[S_SIZE + 1];
  };
  static struct nf_log_buf emergency, *emergency_ptr = &emergency;
  
  __printf(2, 3) int nf_log_buf_add(struct nf_log_buf *m, const char *f, ...)
  {
  	va_list args;
  	int len;
  
  	if (likely(m->count < S_SIZE)) {
  		va_start(args, f);
  		len = vsnprintf(m->buf + m->count, S_SIZE - m->count, f, args);
  		va_end(args);
  		if (likely(m->count + len < S_SIZE)) {
  			m->count += len;
  			return 0;
  		}
  	}
  	m->count = S_SIZE;
  	printk_once(KERN_ERR KBUILD_MODNAME " please increase S_SIZE\n");
  	return -1;
  }
  EXPORT_SYMBOL_GPL(nf_log_buf_add);
  
  struct nf_log_buf *nf_log_buf_open(void)
  {
  	struct nf_log_buf *m = kmalloc(sizeof(*m), GFP_ATOMIC);
  
  	if (unlikely(!m)) {
  		local_bh_disable();
  		do {
  			m = xchg(&emergency_ptr, NULL);
  		} while (!m);
  	}
  	m->count = 0;
  	return m;
  }
  EXPORT_SYMBOL_GPL(nf_log_buf_open);
  
  void nf_log_buf_close(struct nf_log_buf *m)
  {
  	m->buf[m->count] = 0;
  	printk("%s\n", m->buf);
  
  	if (likely(m != &emergency))
  		kfree(m);
  	else {
  		emergency_ptr = m;
  		local_bh_enable();
  	}
  }
  EXPORT_SYMBOL_GPL(nf_log_buf_close);
  
  #ifdef CONFIG_PROC_FS
  static void *seq_start(struct seq_file *seq, loff_t *pos)
  {
  	struct net *net = seq_file_net(seq);
  
  	mutex_lock(&nf_log_mutex);
  
  	if (*pos >= ARRAY_SIZE(net->nf.nf_loggers))
  		return NULL;
  
  	return pos;
  }
  
  static void *seq_next(struct seq_file *s, void *v, loff_t *pos)
  {
  	struct net *net = seq_file_net(s);
  
  	(*pos)++;
  
  	if (*pos >= ARRAY_SIZE(net->nf.nf_loggers))
  		return NULL;
  
  	return pos;
  }
  
  static void seq_stop(struct seq_file *s, void *v)
  {
  	mutex_unlock(&nf_log_mutex);
  }
  
  static int seq_show(struct seq_file *s, void *v)
  {
  	loff_t *pos = v;
  	const struct nf_logger *logger;
  	int i;
  	struct net *net = seq_file_net(s);
  
  	logger = nft_log_dereference(net->nf.nf_loggers[*pos]);
  
  	if (!logger)
  		seq_printf(s, "%2lld NONE (", *pos);
  	else
  		seq_printf(s, "%2lld %s (", *pos, logger->name);
  
  	if (seq_has_overflowed(s))
  		return -ENOSPC;
  
  	for (i = 0; i < NF_LOG_TYPE_MAX; i++) {
  		if (loggers[*pos][i] == NULL)
  			continue;
  
  		logger = nft_log_dereference(loggers[*pos][i]);
  		seq_printf(s, "%s", logger->name);
  		if (i == 0 && loggers[*pos][i + 1] != NULL)
  			seq_puts(s, ",");
  
  		if (seq_has_overflowed(s))
  			return -ENOSPC;
  	}
  
  	seq_puts(s, ")\n");
  
  	if (seq_has_overflowed(s))
  		return -ENOSPC;
  	return 0;
  }
  
  static const struct seq_operations nflog_seq_ops = {
  	.start	= seq_start,
  	.next	= seq_next,
  	.stop	= seq_stop,
  	.show	= seq_show,
  };
  #endif /* PROC_FS */
  
  #ifdef CONFIG_SYSCTL
  static char nf_log_sysctl_fnames[NFPROTO_NUMPROTO-NFPROTO_UNSPEC][3];
  static struct ctl_table nf_log_sysctl_table[NFPROTO_NUMPROTO+1];
  static struct ctl_table_header *nf_log_sysctl_fhdr;
  
  static struct ctl_table nf_log_sysctl_ftable[] = {
  	{
  		.procname	= "nf_log_all_netns",
  		.data		= &sysctl_nf_log_all_netns,
  		.maxlen		= sizeof(sysctl_nf_log_all_netns),
  		.mode		= 0644,
  		.proc_handler	= proc_dointvec,
  	},
  	{ }
  };
  
  static int nf_log_proc_dostring(struct ctl_table *table, int write,
  			 void __user *buffer, size_t *lenp, loff_t *ppos)
  {
  	const struct nf_logger *logger;
  	char buf[NFLOGGER_NAME_LEN];
  	int r = 0;
  	int tindex = (unsigned long)table->extra1;
  	struct net *net = table->extra2;
  
  	if (write) {
  		struct ctl_table tmp = *table;
  
  		/* proc_dostring() can append to existing strings, so we need to
  		 * initialize it as an empty string.
  		 */
  		buf[0] = '\0';
  		tmp.data = buf;
  		r = proc_dostring(&tmp, write, buffer, lenp, ppos);
  		if (r)
  			return r;
  
  		if (!strcmp(buf, "NONE")) {
  			nf_log_unbind_pf(net, tindex);
  			return 0;
  		}
  		mutex_lock(&nf_log_mutex);
  		logger = __find_logger(tindex, buf);
  		if (logger == NULL) {
  			mutex_unlock(&nf_log_mutex);
  			return -ENOENT;
  		}
  		rcu_assign_pointer(net->nf.nf_loggers[tindex], logger);
  		mutex_unlock(&nf_log_mutex);
  	} else {
  		struct ctl_table tmp = *table;
  
  		tmp.data = buf;
  		mutex_lock(&nf_log_mutex);
  		logger = nft_log_dereference(net->nf.nf_loggers[tindex]);
  		if (!logger)
  			strlcpy(buf, "NONE", sizeof(buf));
  		else
  			strlcpy(buf, logger->name, sizeof(buf));
  		mutex_unlock(&nf_log_mutex);
  		r = proc_dostring(&tmp, write, buffer, lenp, ppos);
  	}
  
  	return r;
  }
  
  static int netfilter_log_sysctl_init(struct net *net)
  {
  	int i;
  	struct ctl_table *table;
  
  	table = nf_log_sysctl_table;
  	if (!net_eq(net, &init_net)) {
  		table = kmemdup(nf_log_sysctl_table,
  				 sizeof(nf_log_sysctl_table),
  				 GFP_KERNEL);
  		if (!table)
  			goto err_alloc;
  	} else {
  		for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++) {
  			snprintf(nf_log_sysctl_fnames[i],
  				 3, "%d", i);
  			nf_log_sysctl_table[i].procname	=
  				nf_log_sysctl_fnames[i];
  			nf_log_sysctl_table[i].maxlen = NFLOGGER_NAME_LEN;
  			nf_log_sysctl_table[i].mode = 0644;
  			nf_log_sysctl_table[i].proc_handler =
  				nf_log_proc_dostring;
  			nf_log_sysctl_table[i].extra1 =
  				(void *)(unsigned long) i;
  		}
  		nf_log_sysctl_fhdr = register_net_sysctl(net, "net/netfilter",
  							 nf_log_sysctl_ftable);
  		if (!nf_log_sysctl_fhdr)
  			goto err_freg;
  	}
  
  	for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++)
  		table[i].extra2 = net;
  
  	net->nf.nf_log_dir_header = register_net_sysctl(net,
  						"net/netfilter/nf_log",
  						table);
  	if (!net->nf.nf_log_dir_header)
  		goto err_reg;
  
  	return 0;
  
  err_reg:
  	if (!net_eq(net, &init_net))
  		kfree(table);
  	else
  		unregister_net_sysctl_table(nf_log_sysctl_fhdr);
  err_freg:
  err_alloc:
  	return -ENOMEM;
  }
  
  static void netfilter_log_sysctl_exit(struct net *net)
  {
  	struct ctl_table *table;
  
  	table = net->nf.nf_log_dir_header->ctl_table_arg;
  	unregister_net_sysctl_table(net->nf.nf_log_dir_header);
  	if (!net_eq(net, &init_net))
  		kfree(table);
  	else
  		unregister_net_sysctl_table(nf_log_sysctl_fhdr);
  }
  #else
  static int netfilter_log_sysctl_init(struct net *net)
  {
  	return 0;
  }
  
  static void netfilter_log_sysctl_exit(struct net *net)
  {
  }
  #endif /* CONFIG_SYSCTL */
  
  static int __net_init nf_log_net_init(struct net *net)
  {
  	int ret = -ENOMEM;
  
  #ifdef CONFIG_PROC_FS
  	if (!proc_create_net("nf_log", 0444, net->nf.proc_netfilter,
  			&nflog_seq_ops, sizeof(struct seq_net_private)))
  		return ret;
  #endif
  	ret = netfilter_log_sysctl_init(net);
  	if (ret < 0)
  		goto out_sysctl;
  
  	return 0;
  
  out_sysctl:
  #ifdef CONFIG_PROC_FS
  	remove_proc_entry("nf_log", net->nf.proc_netfilter);
  #endif
  	return ret;
  }
  
  static void __net_exit nf_log_net_exit(struct net *net)
  {
  	netfilter_log_sysctl_exit(net);
  #ifdef CONFIG_PROC_FS
  	remove_proc_entry("nf_log", net->nf.proc_netfilter);
  #endif
  }
  
  static struct pernet_operations nf_log_net_ops = {
  	.init = nf_log_net_init,
  	.exit = nf_log_net_exit,
  };
  
  int __init netfilter_log_init(void)
  {
  	return register_pernet_subsys(&nf_log_net_ops);
  }
  