netlink: add a basic rtnetlink parser of link messages

* netlink_route.h: New file.
* rtnl_link.c: Likewise.
* Makefile.am (strace_SOURCES): Add them.
* defs.h (arp_hardware_types, iffflags): New xlat prototypes.
* netlink_route.c: Include "netlink_route.h"
and <linux/rtnetlink.h>.
(netlink_route_decoder_t): New typedef.
(route_decoders): New array.
(decode_netlink_route): Use it.

Co-authored-by: Fabien Siron <fabien.siron@epita.fr>

Makefile.am

@@ -194,6 +194,7 @@ strace_SOURCES =	\
 	netlink_netlink_diag.c \
 	netlink_packet_diag.c \
 	netlink_route.c	\
+	netlink_route.h	\
 	netlink_selinux.c \
 	netlink_smc_diag.c \
 	netlink_sock_diag.c \
@@ -246,6 +247,7 @@ strace_SOURCES =	\
 	rt_sigframe.c	\
 	rt_sigreturn.c	\
 	rtc.c		\
+	rtnl_link.c	\
 	sched.c		\
 	sched_attr.h	\
 	scsi.c		\

defs.h

@@ -284,11 +284,13 @@ struct tcb {
 #include "xlat.h"
 
 extern const struct xlat addrfams[];
+extern const struct xlat arp_hardware_types[];
 extern const struct xlat at_flags[];
 extern const struct xlat clocknames[];
 extern const struct xlat dirent_types[];
 extern const struct xlat ethernet_protocols[];
 extern const struct xlat evdev_abs[];
+extern const struct xlat iffflags[];
 extern const struct xlat inet_protocols[];
 extern const struct xlat msg_flags[];
 extern const struct xlat netlink_protocols[];

netlink_route.c

@@ -29,6 +29,9 @@
 
 #include "defs.h"
 #include "netlink.h"
+#include "netlink_route.h"
+
+#include <linux/rtnetlink.h>
 
 #include "xlat/nl_route_types.h"
 
@@ -46,6 +49,15 @@ decode_family(struct tcb *const tcp, const uint8_t family,
 	tprints("}");
 }
 
+typedef DECL_NETLINK_ROUTE_DECODER((*netlink_route_decoder_t));
+
+static const netlink_route_decoder_t route_decoders[] = {
+	[RTM_DELLINK - RTM_BASE] = decode_ifinfomsg,
+	[RTM_GETLINK - RTM_BASE] = decode_ifinfomsg,
+	[RTM_NEWLINK - RTM_BASE] = decode_ifinfomsg,
+	[RTM_SETLINK - RTM_BASE] = decode_ifinfomsg
+};
+
 bool
 decode_netlink_route(struct tcb *const tcp,
 		     const struct nlmsghdr *const nlmsghdr,
@@ -57,8 +69,16 @@ decode_netlink_route(struct tcb *const tcp,
 	if (nlmsghdr->nlmsg_type == NLMSG_DONE)
 		return false;
 
-	if (!umove_or_printaddr(tcp, addr, &family))
+	if (!umove_or_printaddr(tcp, addr, &family)) {
-		decode_family(tcp, family, addr, len);
+		const unsigned int index = nlmsghdr->nlmsg_type - RTM_BASE;
+
+		if (index < ARRAY_SIZE(route_decoders)
+		    && route_decoders[index]) {
+			route_decoders[index](tcp, nlmsghdr, family, addr, len);
+		} else {
+			decode_family(tcp, family, addr, len);
+		}
+	}
 
 	return true;
 }

netlink_route.h

@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) 2016 Fabien Siron <fabien.siron@epita.fr>
+ * Copyright (c) 2017 JingPiao Chen <chenjingpiao@gmail.com>
+ * Copyright (c) 2016-2017 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.
+ */
+
+#ifndef STRACE_NETLINK_ROUTE_H
+#define STRACE_NETLINK_ROUTE_H
+
+#define DECL_NETLINK_ROUTE_DECODER(route_decode_name)	\
+void							\
+route_decode_name(struct tcb *tcp,			\
+		  const struct nlmsghdr *nlmsghdr,	\
+		  uint8_t family,			\
+		  kernel_ulong_t addr,			\
+		  unsigned int len)			\
+/* End of DECL_NETLINK_ROUTE_DECODER definition. */
+
+extern DECL_NETLINK_ROUTE_DECODER(decode_ifinfomsg);
+
+#endif /* !STRACE_NETLINK_ROUTE_H */

rtnl_link.c

@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2016 Fabien Siron <fabien.siron@epita.fr>
+ * Copyright (c) 2017 JingPiao Chen <chenjingpiao@gmail.com>
+ * Copyright (c) 2016-2017 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"
+#include "netlink_route.h"
+#include "print_fields.h"
+
+#include <linux/rtnetlink.h>
+
+DECL_NETLINK_ROUTE_DECODER(decode_ifinfomsg)
+{
+	struct ifinfomsg ifinfo = { .ifi_family = family };
+	const size_t offset = sizeof(ifinfo.ifi_family);
+
+	PRINT_FIELD_XVAL("{", ifinfo, ifi_family, addrfams, "AF_???");
+
+	tprints(", ");
+	if (len >= sizeof(ifinfo)) {
+		if (!umoven_or_printaddr(tcp, addr + offset,
+					 sizeof(ifinfo) - offset,
+					 (void *) &ifinfo + offset)) {
+			PRINT_FIELD_XVAL("", ifinfo, ifi_type,
+					 arp_hardware_types, "ARPHRD_???");
+			PRINT_FIELD_IFINDEX(", ", ifinfo, ifi_index);
+			PRINT_FIELD_FLAGS(", ", ifinfo, ifi_flags,
+					  iffflags, "IFF_???");
+			PRINT_FIELD_X(", ", ifinfo, ifi_change);
+		}
+	} else
+		tprints("...");
+	tprints("}");
+}