[PATCH v4 01/10] netlink: introduce a dummy netlink attributes parser

JingPiao Chen chenjingpiao at gmail.com
Tue Jun 20 09:23:46 UTC 2017


* linux/unix_diag.h (UNIX_DIAG_*): New enum.
* nlattr.c: New file.
* nlattr.h: Likewise.
* Makefile.am (strace_SOURCES): Add them.
* netlink_sock_diag.c: Include "nlattr.h" and "xlat/unix_diag_attrs.h".
(decode_unix_diag_msg): Use decode_nlattr.
* xlat/unix_diag_attrs.in: New file.

co-authored-by: Fabien Siron <fabien.siron at epita.fr>
---
 Makefile.am             |   2 +
 linux/unix_diag.h       |  11 +++-
 netlink_sock_diag.c     |  13 ++++-
 nlattr.c                | 131 ++++++++++++++++++++++++++++++++++++++++++++++++
 nlattr.h                |  32 ++++++++++++
 xlat/unix_diag_attrs.in |   8 +++
 6 files changed, 194 insertions(+), 3 deletions(-)
 create mode 100644 nlattr.c
 create mode 100644 nlattr.h
 create mode 100644 xlat/unix_diag_attrs.in

diff --git a/Makefile.am b/Makefile.am
index f9e78ed..50bf832 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -174,6 +174,8 @@ strace_SOURCES =	\
 	net.c		\
 	netlink.c       \
 	netlink_sock_diag.c \
+	nlattr.c	\
+	nlattr.h	\
 	nsfs.c          \
 	nsfs.h          \
 	nsig.h		\
diff --git a/linux/unix_diag.h b/linux/unix_diag.h
index a6b62ba..3c9d99f 100644
--- a/linux/unix_diag.h
+++ b/linux/unix_diag.h
@@ -27,7 +27,14 @@ struct unix_diag_msg {
 	uint32_t udiag_cookie[2];
 };
 
-#define UNIX_DIAG_NAME 0
-#define UNIX_DIAG_PEER 2
+enum {
+	UNIX_DIAG_NAME,
+	UNIX_DIAG_VFS,
+	UNIX_DIAG_PEER,
+	UNIX_DIAG_ICONS,
+	UNIX_DIAG_RQLEN,
+	UNIX_DIAG_MEMINFO,
+	UNIX_DIAG_SHUTDOWN,
+};
 
 #endif /* !STRACE_LINUX_UNIX_DIAG_H */
diff --git a/netlink_sock_diag.c b/netlink_sock_diag.c
index 8dbfd07..f92253e 100644
--- a/netlink_sock_diag.c
+++ b/netlink_sock_diag.c
@@ -28,6 +28,7 @@
  */
 
 #include "defs.h"
+#include "nlattr.h"
 
 #include <sys/socket.h>
 #include <arpa/inet.h>
@@ -55,6 +56,7 @@
 # include "xlat/smc_states.h"
 #endif
 
+#include "xlat/unix_diag_attrs.h"
 #include "xlat/unix_diag_show.h"
 
 static void
@@ -113,7 +115,8 @@ decode_unix_diag_msg(struct tcb *const tcp,
 		     const kernel_ulong_t len)
 {
 	struct unix_diag_msg msg = { .udiag_family = family };
-	const size_t offset = sizeof(msg.udiag_family);
+	size_t offset = sizeof(msg.udiag_family);
+	bool decode_nla = false;
 
 	tprints("{udiag_family=");
 	printxval(addrfams, msg.udiag_family, "AF_???");
@@ -131,10 +134,18 @@ decode_unix_diag_msg(struct tcb *const tcp,
 				", udiag_cookie=[%" PRIu32 ", %" PRIu32 "]",
 				msg.udiag_ino,
 				msg.udiag_cookie[0], msg.udiag_cookie[1]);
+			decode_nla = true;
 		}
 	} else
 		tprints("...");
 	tprints("}");
+
+	offset = NLMSG_ALIGN(sizeof(msg));
+	if (decode_nla && len > offset) {
+		tprints(", ");
+		decode_nlattr(tcp, addr + offset, len - offset,
+			      unix_diag_attrs, "UNIX_DIAG_???");
+	}
 }
 
 static void
diff --git a/nlattr.c b/nlattr.c
new file mode 100644
index 0000000..eaf7e39
--- /dev/null
+++ b/nlattr.c
@@ -0,0 +1,131 @@
+/*
+ * Copyright (c) 2016 Fabien Siron <fabien.siron at epita.fr>
+ * Copyright (c) 2017 JingPiao Chen <chenjingpiao at 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 <linux/netlink.h>
+
+static bool
+fetch_nlattr(struct tcb *const tcp, struct nlattr *const nlattr,
+	     const kernel_ulong_t addr, const kernel_ulong_t len)
+{
+	if (len < sizeof(struct nlattr)) {
+		printstrn(tcp, addr, len);
+		return false;
+	}
+
+	if (umove_or_printaddr(tcp, addr, nlattr))
+		return false;
+
+	return true;
+}
+
+static void
+print_nlattr(const struct nlattr *const nla,
+	     const struct xlat *const table,
+	     const char *const dflt)
+{
+	tprintf("{nla_len=%u, nla_type=", nla->nla_len);
+	if (nla->nla_type & NLA_F_NESTED)
+		tprints("NLA_F_NESTED|");
+	if (nla->nla_type & NLA_F_NET_BYTEORDER)
+		tprints("NLA_F_NET_BYTEORDER|");
+	printxval(table, nla->nla_type & NLA_TYPE_MASK, dflt);
+	tprints("}");
+}
+
+static void
+decode_nlattr_with_data(struct tcb *tcp,
+			const struct nlattr *const nla,
+			kernel_ulong_t addr,
+			kernel_ulong_t len,
+			const struct xlat *const table,
+			const char *const dflt)
+{
+	unsigned int nla_len = nla->nla_len > len ? len : nla->nla_len;
+
+	if (nla_len > NLA_HDRLEN)
+		tprints("{");
+
+	print_nlattr(nla, table, dflt);
+
+	if (nla_len > NLA_HDRLEN) {
+		tprints(", ");
+		printstrn(tcp, addr + NLA_HDRLEN, nla_len - NLA_HDRLEN);
+		tprints("}");
+	}
+}
+
+void
+decode_nlattr(struct tcb *const tcp,
+	      kernel_ulong_t addr,
+	      kernel_ulong_t len,
+	      const struct xlat *const table,
+	      const char *const dflt)
+{
+	struct nlattr nla;
+	bool print_array = false;
+	unsigned int elt;
+
+	for (elt = 0; fetch_nlattr(tcp, &nla, addr, len); elt++) {
+		if (abbrev(tcp) && elt == max_strlen) {
+			tprints("...");
+			break;
+		}
+
+		unsigned long nla_len = NLA_ALIGN(nla.nla_len);
+		kernel_ulong_t next_addr = 0;
+		kernel_ulong_t next_len = 0;
+
+		if (nla.nla_len >= NLA_HDRLEN) {
+			next_len = (len >= nla_len) ? len - nla_len : 0;
+
+			if (next_len && addr + nla_len > addr)
+				next_addr = addr + nla_len;
+		}
+
+		if (!print_array && next_addr) {
+			tprints("[");
+			print_array = true;
+		}
+
+		decode_nlattr_with_data(tcp, &nla, addr, len, table, dflt);
+
+		if (!next_addr)
+			break;
+
+		tprints(", ");
+		addr = next_addr;
+		len = next_len;
+	}
+
+	if (print_array) {
+		tprints("]");
+	}
+}
diff --git a/nlattr.h b/nlattr.h
new file mode 100644
index 0000000..6b94fc1
--- /dev/null
+++ b/nlattr.h
@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2016 Fabien Siron <fabien.siron at epita.fr>
+ * Copyright (c) 2017 JingPiao Chen <chenjingpiao at 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.
+ */
+
+extern void
+decode_nlattr(struct tcb *, kernel_ulong_t addr, kernel_ulong_t len,
+	      const struct xlat *, const char *);
diff --git a/xlat/unix_diag_attrs.in b/xlat/unix_diag_attrs.in
new file mode 100644
index 0000000..4c3d9b2
--- /dev/null
+++ b/xlat/unix_diag_attrs.in
@@ -0,0 +1,8 @@
+#unconditional
+UNIX_DIAG_NAME
+UNIX_DIAG_VFS
+UNIX_DIAG_PEER
+UNIX_DIAG_ICONS
+UNIX_DIAG_RQLEN
+UNIX_DIAG_MEMINFO
+UNIX_DIAG_SHUTDOWN
-- 
2.7.4





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