[PATCH v3 1/4] netlink: introduce NETLINK_NETFILTER parser

[Chen Jingpiao]

* 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                |  1 +
 defs.h                     |  1 +
 netlink.c                  |  3 ++
 netlink_netfilter.c        | 97 ++++++++++++++++++++++++++++++++++++++
 xlat/netfilter_versions.in |  2 +
 5 files changed, 104 insertions(+)
 create mode 100644 netlink_netfilter.c
 create mode 100644 xlat/netfilter_versions.in

diff --git a/Makefile.am b/Makefile.am
index 3bc546d19..181a0f8e6 100644
--- a/Makefile.am
+++ b/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	\
diff --git a/defs.h b/defs.h
index b4170af48..e48502c1f 100644
--- a/defs.h
+++ b/defs.h
@@ -704,6 +704,7 @@ 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);
diff --git a/netlink.c b/netlink.c
index beb6ea4a9..f5fa1f13a 100644
--- a/netlink.c
+++ b/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,
diff --git a/netlink_netfilter.c b/netlink_netfilter.c
new file mode 100644
index 000000000..49c8e99b9
--- /dev/null
+++ b/netlink_netfilter.c
@@ -0,0 +1,97 @@
+/*
+ * Copyright (c) 2018 Chen Jingpiao <chenjingpiao at 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
+		    && nfmsg.res_id == NFNL_SUBSYS_NFTABLES) {
+# ifdef WORDS_BIGENDIAN
+			tprints("htons(NFNL_SUBSYS_NFTABLES)");
+# else
+			tprints("NFNL_SUBSYS_NFTABLES");
+# endif
+		} else {
+			tprints("htons(");
+			if (subsys_id == NFNL_SUBSYS_NFTABLES
+			    && res_id == NFNL_SUBSYS_NFTABLES)
+				tprints("NFNL_SUBSYS_NFTABLES");
+			else
+				tprintf("%d", res_id);
+			tprints(")");
+		}
+
+		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 */
diff --git a/xlat/netfilter_versions.in b/xlat/netfilter_versions.in
new file mode 100644
index 000000000..da6cd0537
--- /dev/null
+++ b/xlat/netfilter_versions.in
@@ -0,0 +1,2 @@
+NFNETLINK_V0
+NFNETLINK_V1
-- 
2.16.2.347.gba1b3b449.dirty