netlink: introduce NETLINK_NETFILTER parser

* netlink_netfilter.c: New file.
* Makefile.am (strace_SOURCES): Add it.
* defs.h (decode_netlink_netfilter): New prototype.
* netlink.c (netlink_decoders): Add NETLINK_NETFILTER.
* xlat/netfilter_versions.in: New file.

Makefile.am

@@ -202,6 +202,7 @@ strace_SOURCES =	\
 	netlink_crypto.c \
 	netlink_sock_diag.h \
 	netlink_inet_diag.c \
+	netlink_netfilter.c \
 	netlink_netlink_diag.c \
 	netlink_packet_diag.c \
 	netlink_route.c	\

defs.h

@@ -717,6 +717,7 @@ decode_netlink_ ## name(struct tcb *, const struct nlmsghdr *,		\
 /* End of DECL_NETLINK definition. */
 
 DECL_NETLINK(crypto);
+DECL_NETLINK(netfilter);
 DECL_NETLINK(route);
 DECL_NETLINK(selinux);
 DECL_NETLINK(sock_diag);

netlink.c

@@ -548,6 +548,9 @@ decode_nlmsgerr(struct tcb *const tcp,
 static const netlink_decoder_t netlink_decoders[] = {
 #ifdef HAVE_LINUX_CRYPTOUSER_H
 	[NETLINK_CRYPTO] = decode_netlink_crypto,
+#endif
+#ifdef HAVE_LINUX_NETFILTER_NFNETLINK_H
+	[NETLINK_NETFILTER] = decode_netlink_netfilter,
 #endif
 	[NETLINK_ROUTE] = decode_netlink_route,
 	[NETLINK_SELINUX] = decode_netlink_selinux,

netlink_netfilter.c

@@ -0,0 +1,90 @@
+/*
+ * Copyright (c) 2018 Chen Jingpiao <chenjingpiao@gmail.com>
+ * Copyright (c) 2018 The strace developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "defs.h"
+
+#ifdef HAVE_LINUX_NETFILTER_NFNETLINK_H
+
+# include "print_fields.h"
+
+# include <netinet/in.h>
+# include <arpa/inet.h>
+# include "netlink.h"
+# include <linux/netfilter/nfnetlink.h>
+
+# include "xlat/netfilter_versions.h"
+# include "xlat/nl_netfilter_subsys_ids.h"
+
+bool
+decode_netlink_netfilter(struct tcb *const tcp,
+			 const struct nlmsghdr *const nlmsghdr,
+			 const kernel_ulong_t addr,
+			 const unsigned int len)
+{
+	if (nlmsghdr->nlmsg_type == NLMSG_DONE)
+		return false;
+
+	struct nfgenmsg nfmsg;
+
+	if (len < sizeof(nfmsg))
+		printstr_ex(tcp, addr, len, QUOTE_FORCE_HEX);
+	else if (!umove_or_printaddr(tcp, addr, &nfmsg)) {
+		const uint8_t subsys_id = (uint8_t) (nlmsghdr->nlmsg_type >> 8);
+		uint16_t res_id = ntohs(nfmsg.res_id);
+
+		PRINT_FIELD_XVAL("{", nfmsg, nfgen_family, addrfams, "AF_???");
+		PRINT_FIELD_XVAL(", ", nfmsg, version, netfilter_versions,
+				 "NFNETLINK_???");
+
+		/*
+		 * Work around wrong endianness in res_id field,
+		 * see linux commit v4.3-rc1~28^2~47^2~1
+		 */
+		tprints(", res_id=");
+		if (subsys_id == NFNL_SUBSYS_NFTABLES
+		    && res_id == NFNL_SUBSYS_NFTABLES) {
+			tprints("htons(NFNL_SUBSYS_NFTABLES)");
+		} else if (subsys_id == NFNL_SUBSYS_NFTABLES
+			   && nfmsg.res_id == NFNL_SUBSYS_NFTABLES) {
+			tprints("NFNL_SUBSYS_NFTABLES");
+		} else {
+			tprintf("htons(%d)", res_id);
+		}
+
+		const size_t offset = NLMSG_ALIGN(sizeof(nfmsg));
+		if (len > offset) {
+			tprints(", ");
+			printstr_ex(tcp, addr + offset,
+				    len - offset, QUOTE_FORCE_HEX);
+		}
+	}
+
+	return true;
+}
+
+#endif /* HAVE_LINUX_NETFILTER_NFNETLINK_H */

xlat/netfilter_versions.in

@@ -0,0 +1,2 @@
+NFNETLINK_V0	0
+NFNETLINK_V1	1