netfilter: nf_log_ipv4: rename to nf_log_syslog

Netfilter has multiple log modules:
 nf_log_arp
 nf_log_bridge
 nf_log_ipv4
 nf_log_ipv6
 nf_log_netdev
 nfnetlink_log
 nf_log_common

With the exception of nfnetlink_log (packet is sent to userspace for
dissection/logging), all of them log to the kernel ringbuffer.

This is the first part of a series to merge all modules except
nfnetlink_log into a single module: nf_log_syslog.

This allows to reduce code.  After the series, only two log modules remain:
nfnetlink_log and nf_log_syslog. The latter provides the same
functionality as the old per-af log modules.

This renames nf_log_ipv4 to nf_log_syslog.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

3 files changed, 405 insertions, 1 deletions

diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index 1a92063c73a4..d5c047190eb9 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -78,6 +78,18 @@ config NF_LOG_NETDEV
 	tristate "Netdev packet logging"
 	select NF_LOG_COMMON
 
+config NF_LOG_SYSLOG
+	tristate "Syslog packet logging"
+	default m if NETFILTER_ADVANCED=n
+	select NF_LOG_COMMON
+	help
+	  This option enable support for packet logging via syslog.
+	  It supports IPv4 and common transport protocols such as TCP and UDP.
+	  This is a simpler but less flexible logging method compared to
+	  CONFIG_NETFILTER_NETLINK_LOG.
+	  If both are enabled the backend to use can be configured at run-time
+	  by means of per-address-family sysctl tunables.
+
 if NF_CONNTRACK
 config NETFILTER_CONNCOUNT
 	tristate
@@ -923,7 +935,7 @@ config NETFILTER_XT_TARGET_LED
 config NETFILTER_XT_TARGET_LOG
 	tristate "LOG target support"
 	select NF_LOG_COMMON
-	select NF_LOG_IPV4
+	select NF_LOG_SYSLOG
 	select NF_LOG_IPV6 if IP6_NF_IPTABLES
 	default m if NETFILTER_ADVANCED=n
 	help
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index 33da7bf1b68e..59642d9ab7a5 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -50,6 +50,7 @@ nf_nat-y	:= nf_nat_core.o nf_nat_proto.o nf_nat_helper.o
 
 # generic transport layer logging
 obj-$(CONFIG_NF_LOG_COMMON) += nf_log_common.o
+obj-$(CONFIG_NF_LOG_SYSLOG) += nf_log_syslog.o
 
 # packet logging for netdev family
 obj-$(CONFIG_NF_LOG_NETDEV) += nf_log_netdev.o
diff --git a/net/netfilter/nf_log_syslog.c b/net/netfilter/nf_log_syslog.c
new file mode 100644
index 000000000000..e6fe156e77c7
--- /dev/null
+++ b/net/netfilter/nf_log_syslog.c
@@ -0,0 +1,391 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* (C) 1999-2001 Paul `Rusty' Russell
+ * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/spinlock.h>
+#include <linux/skbuff.h>
+#include <linux/if_arp.h>
+#include <linux/ip.h>
+#include <net/ipv6.h>
+#include <net/icmp.h>
+#include <net/udp.h>
+#include <net/tcp.h>
+#include <net/route.h>
+
+#include <linux/netfilter.h>
+#include <linux/netfilter/xt_LOG.h>
+#include <net/netfilter/nf_log.h>
+
+static const struct nf_loginfo default_loginfo = {
+	.type	= NF_LOG_TYPE_LOG,
+	.u = {
+		.log = {
+			.level	  = LOGLEVEL_NOTICE,
+			.logflags = NF_LOG_DEFAULT_MASK,
+		},
+	},
+};
+
+/* One level of recursion won't kill us */
+static noinline_for_stack void
+dump_ipv4_packet(struct net *net, struct nf_log_buf *m,
+		 const struct nf_loginfo *info,
+		 const struct sk_buff *skb, unsigned int iphoff)
+{
+	const struct iphdr *ih;
+	unsigned int logflags;
+	struct iphdr _iph;
+
+	if (info->type == NF_LOG_TYPE_LOG)
+		logflags = info->u.log.logflags;
+	else
+		logflags = NF_LOG_DEFAULT_MASK;
+
+	ih = skb_header_pointer(skb, iphoff, sizeof(_iph), &_iph);
+	if (!ih) {
+		nf_log_buf_add(m, "TRUNCATED");
+		return;
+	}
+
+	/* Important fields:
+	 * TOS, len, DF/MF, fragment offset, TTL, src, dst, options.
+	 * Max length: 40 "SRC=255.255.255.255 DST=255.255.255.255 "
+	 */
+	nf_log_buf_add(m, "SRC=%pI4 DST=%pI4 ", &ih->saddr, &ih->daddr);
+
+	/* Max length: 46 "LEN=65535 TOS=0xFF PREC=0xFF TTL=255 ID=65535 " */
+	nf_log_buf_add(m, "LEN=%u TOS=0x%02X PREC=0x%02X TTL=%u ID=%u ",
+		       ntohs(ih->tot_len), ih->tos & IPTOS_TOS_MASK,
+		       ih->tos & IPTOS_PREC_MASK, ih->ttl, ntohs(ih->id));
+
+	/* Max length: 6 "CE DF MF " */
+	if (ntohs(ih->frag_off) & IP_CE)
+		nf_log_buf_add(m, "CE ");
+	if (ntohs(ih->frag_off) & IP_DF)
+		nf_log_buf_add(m, "DF ");
+	if (ntohs(ih->frag_off) & IP_MF)
+		nf_log_buf_add(m, "MF ");
+
+	/* Max length: 11 "FRAG:65535 " */
+	if (ntohs(ih->frag_off) & IP_OFFSET)
+		nf_log_buf_add(m, "FRAG:%u ", ntohs(ih->frag_off) & IP_OFFSET);
+
+	if ((logflags & NF_LOG_IPOPT) &&
+	    ih->ihl * 4 > sizeof(struct iphdr)) {
+		unsigned char _opt[4 * 15 - sizeof(struct iphdr)];
+		const unsigned char *op;
+		unsigned int i, optsize;
+
+		optsize = ih->ihl * 4 - sizeof(struct iphdr);
+		op = skb_header_pointer(skb, iphoff + sizeof(_iph),
+					optsize, _opt);
+		if (!op) {
+			nf_log_buf_add(m, "TRUNCATED");
+			return;
+		}
+
+		/* Max length: 127 "OPT (" 15*4*2chars ") " */
+		nf_log_buf_add(m, "OPT (");
+		for (i = 0; i < optsize; i++)
+			nf_log_buf_add(m, "%02X", op[i]);
+		nf_log_buf_add(m, ") ");
+	}
+
+	switch (ih->protocol) {
+	case IPPROTO_TCP:
+		if (nf_log_dump_tcp_header(m, skb, ih->protocol,
+					   ntohs(ih->frag_off) & IP_OFFSET,
+					   iphoff + ih->ihl * 4, logflags))
+			return;
+		break;
+	case IPPROTO_UDP:
+	case IPPROTO_UDPLITE:
+		if (nf_log_dump_udp_header(m, skb, ih->protocol,
+					   ntohs(ih->frag_off) & IP_OFFSET,
+					   iphoff + ih->ihl * 4))
+			return;
+		break;
+	case IPPROTO_ICMP: {
+		static const size_t required_len[NR_ICMP_TYPES + 1] = {
+			[ICMP_ECHOREPLY] = 4,
+			[ICMP_DEST_UNREACH] = 8 + sizeof(struct iphdr),
+			[ICMP_SOURCE_QUENCH] = 8 + sizeof(struct iphdr),
+			[ICMP_REDIRECT] = 8 + sizeof(struct iphdr),
+			[ICMP_ECHO] = 4,
+			[ICMP_TIME_EXCEEDED] = 8 + sizeof(struct iphdr),
+			[ICMP_PARAMETERPROB] = 8 + sizeof(struct iphdr),
+			[ICMP_TIMESTAMP] = 20,
+			[ICMP_TIMESTAMPREPLY] = 20,
+			[ICMP_ADDRESS] = 12,
+			[ICMP_ADDRESSREPLY] = 12 };
+		const struct icmphdr *ich;
+		struct icmphdr _icmph;
+
+		/* Max length: 11 "PROTO=ICMP " */
+		nf_log_buf_add(m, "PROTO=ICMP ");
+
+		if (ntohs(ih->frag_off) & IP_OFFSET)
+			break;
+
+		/* Max length: 25 "INCOMPLETE [65535 bytes] " */
+		ich = skb_header_pointer(skb, iphoff + ih->ihl * 4,
+					 sizeof(_icmph), &_icmph);
+		if (!ich) {
+			nf_log_buf_add(m, "INCOMPLETE [%u bytes] ",
+				       skb->len - iphoff - ih->ihl * 4);
+			break;
+		}
+
+		/* Max length: 18 "TYPE=255 CODE=255 " */
+		nf_log_buf_add(m, "TYPE=%u CODE=%u ", ich->type, ich->code);
+
+		/* Max length: 25 "INCOMPLETE [65535 bytes] " */
+		if (ich->type <= NR_ICMP_TYPES &&
+		    required_len[ich->type] &&
+		    skb->len - iphoff - ih->ihl * 4 < required_len[ich->type]) {
+			nf_log_buf_add(m, "INCOMPLETE [%u bytes] ",
+				       skb->len - iphoff - ih->ihl * 4);
+			break;
+		}
+
+		switch (ich->type) {
+		case ICMP_ECHOREPLY:
+		case ICMP_ECHO:
+			/* Max length: 19 "ID=65535 SEQ=65535 " */
+			nf_log_buf_add(m, "ID=%u SEQ=%u ",
+				       ntohs(ich->un.echo.id),
+				       ntohs(ich->un.echo.sequence));
+			break;
+
+		case ICMP_PARAMETERPROB:
+			/* Max length: 14 "PARAMETER=255 " */
+			nf_log_buf_add(m, "PARAMETER=%u ",
+				       ntohl(ich->un.gateway) >> 24);
+			break;
+		case ICMP_REDIRECT:
+			/* Max length: 24 "GATEWAY=255.255.255.255 " */
+			nf_log_buf_add(m, "GATEWAY=%pI4 ", &ich->un.gateway);
+			fallthrough;
+		case ICMP_DEST_UNREACH:
+		case ICMP_SOURCE_QUENCH:
+		case ICMP_TIME_EXCEEDED:
+			/* Max length: 3+maxlen */
+			if (!iphoff) { /* Only recurse once. */
+				nf_log_buf_add(m, "[");
+				dump_ipv4_packet(net, m, info, skb,
+						 iphoff + ih->ihl * 4 + sizeof(_icmph));
+				nf_log_buf_add(m, "] ");
+			}
+
+			/* Max length: 10 "MTU=65535 " */
+			if (ich->type == ICMP_DEST_UNREACH &&
+			    ich->code == ICMP_FRAG_NEEDED) {
+				nf_log_buf_add(m, "MTU=%u ",
+					       ntohs(ich->un.frag.mtu));
+			}
+		}
+		break;
+	}
+	/* Max Length */
+	case IPPROTO_AH: {
+		const struct ip_auth_hdr *ah;
+		struct ip_auth_hdr _ahdr;
+
+		if (ntohs(ih->frag_off) & IP_OFFSET)
+			break;
+
+		/* Max length: 9 "PROTO=AH " */
+		nf_log_buf_add(m, "PROTO=AH ");
+
+		/* Max length: 25 "INCOMPLETE [65535 bytes] " */
+		ah = skb_header_pointer(skb, iphoff + ih->ihl * 4,
+					sizeof(_ahdr), &_ahdr);
+		if (!ah) {
+			nf_log_buf_add(m, "INCOMPLETE [%u bytes] ",
+				       skb->len - iphoff - ih->ihl * 4);
+			break;
+		}
+
+		/* Length: 15 "SPI=0xF1234567 " */
+		nf_log_buf_add(m, "SPI=0x%x ", ntohl(ah->spi));
+		break;
+	}
+	case IPPROTO_ESP: {
+		const struct ip_esp_hdr *eh;
+		struct ip_esp_hdr _esph;
+
+		/* Max length: 10 "PROTO=ESP " */
+		nf_log_buf_add(m, "PROTO=ESP ");
+
+		if (ntohs(ih->frag_off) & IP_OFFSET)
+			break;
+
+		/* Max length: 25 "INCOMPLETE [65535 bytes] " */
+		eh = skb_header_pointer(skb, iphoff + ih->ihl * 4,
+					sizeof(_esph), &_esph);
+		if (!eh) {
+			nf_log_buf_add(m, "INCOMPLETE [%u bytes] ",
+				       skb->len - iphoff - ih->ihl * 4);
+			break;
+		}
+
+		/* Length: 15 "SPI=0xF1234567 " */
+		nf_log_buf_add(m, "SPI=0x%x ", ntohl(eh->spi));
+		break;
+	}
+	/* Max length: 10 "PROTO 255 " */
+	default:
+		nf_log_buf_add(m, "PROTO=%u ", ih->protocol);
+	}
+
+	/* Max length: 15 "UID=4294967295 " */
+	if ((logflags & NF_LOG_UID) && !iphoff)
+		nf_log_dump_sk_uid_gid(net, m, skb->sk);
+
+	/* Max length: 16 "MARK=0xFFFFFFFF " */
+	if (!iphoff && skb->mark)
+		nf_log_buf_add(m, "MARK=0x%x ", skb->mark);
+
+	/* Proto    Max log string length */
+	/* IP:	    40+46+6+11+127 = 230 */
+	/* TCP:     10+max(25,20+30+13+9+32+11+127) = 252 */
+	/* UDP:     10+max(25,20) = 35 */
+	/* UDPLITE: 14+max(25,20) = 39 */
+	/* ICMP:    11+max(25, 18+25+max(19,14,24+3+n+10,3+n+10)) = 91+n */
+	/* ESP:     10+max(25)+15 = 50 */
+	/* AH:	    9+max(25)+15 = 49 */
+	/* unknown: 10 */
+
+	/* (ICMP allows recursion one level deep) */
+	/* maxlen =  IP + ICMP +  IP + max(TCP,UDP,ICMP,unknown) */
+	/* maxlen = 230+   91  + 230 + 252 = 803 */
+}
+
+static void dump_ipv4_mac_header(struct nf_log_buf *m,
+				 const struct nf_loginfo *info,
+				 const struct sk_buff *skb)
+{
+	struct net_device *dev = skb->dev;
+	unsigned int logflags = 0;
+
+	if (info->type == NF_LOG_TYPE_LOG)
+		logflags = info->u.log.logflags;
+
+	if (!(logflags & NF_LOG_MACDECODE))
+		goto fallback;
+
+	switch (dev->type) {
+	case ARPHRD_ETHER:
+		nf_log_buf_add(m, "MACSRC=%pM MACDST=%pM ",
+			       eth_hdr(skb)->h_source, eth_hdr(skb)->h_dest);
+		nf_log_dump_vlan(m, skb);
+		nf_log_buf_add(m, "MACPROTO=%04x ",
+			       ntohs(eth_hdr(skb)->h_proto));
+		return;
+	default:
+		break;
+	}
+
+fallback:
+	nf_log_buf_add(m, "MAC=");
+	if (dev->hard_header_len &&
+	    skb->mac_header != skb->network_header) {
+		const unsigned char *p = skb_mac_header(skb);
+		unsigned int i;
+
+		nf_log_buf_add(m, "%02x", *p++);
+		for (i = 1; i < dev->hard_header_len; i++, p++)
+			nf_log_buf_add(m, ":%02x", *p);
+	}
+	nf_log_buf_add(m, " ");
+}
+
+static void nf_log_ip_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 *prefix)
+{
+	struct nf_log_buf *m;
+
+	/* FIXME: Disabled from containers until syslog ns is supported */
+	if (!net_eq(net, &init_net) && !sysctl_nf_log_all_netns)
+		return;
+
+	m = nf_log_buf_open();
+
+	if (!loginfo)
+		loginfo = &default_loginfo;
+
+	nf_log_dump_packet_common(m, pf, hooknum, skb, in,
+				  out, loginfo, prefix);
+
+	if (in)
+		dump_ipv4_mac_header(m, loginfo, skb);
+
+	dump_ipv4_packet(net, m, loginfo, skb, 0);
+
+	nf_log_buf_close(m);
+}
+
+static struct nf_logger nf_ip_logger __read_mostly = {
+	.name		= "nf_log_ipv4",
+	.type		= NF_LOG_TYPE_LOG,
+	.logfn		= nf_log_ip_packet,
+	.me		= THIS_MODULE,
+};
+
+static int __net_init nf_log_syslog_net_init(struct net *net)
+{
+	return nf_log_set(net, NFPROTO_IPV4, &nf_ip_logger);
+}
+
+static void __net_exit nf_log_syslog_net_exit(struct net *net)
+{
+	nf_log_unset(net, &nf_ip_logger);
+}
+
+static struct pernet_operations nf_log_syslog_net_ops = {
+	.init = nf_log_syslog_net_init,
+	.exit = nf_log_syslog_net_exit,
+};
+
+static int __init nf_log_syslog_init(void)
+{
+	int ret;
+
+	ret = register_pernet_subsys(&nf_log_syslog_net_ops);
+	if (ret < 0)
+		return ret;
+
+	ret = nf_log_register(NFPROTO_IPV4, &nf_ip_logger);
+	if (ret < 0)
+		goto err1;
+
+	return 0;
+
+err1:
+	unregister_pernet_subsys(&nf_log_syslog_net_ops);
+	return ret;
+}
+
+static void __exit nf_log_syslog_exit(void)
+{
+	unregister_pernet_subsys(&nf_log_syslog_net_ops);
+	nf_log_unregister(&nf_ip_logger);
+}
+
+module_init(nf_log_syslog_init);
+module_exit(nf_log_syslog_exit);
+
+MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
+MODULE_DESCRIPTION("Netfilter syslog packet logging");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("nf_log_ipv4");
+MODULE_ALIAS_NF_LOGGER(AF_INET, 0);