From: Sungbae Yoo <sungbae.yoo@samsung.com>
Date: Wed, 14 Mar 2018 08:48:01 +0000 (+0900)
Subject: Add parsing netlink message header in netlink
X-Git-Tag: submit/tizen/20190219.012108~11
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=977e7d2764fb71e65fcdc0305594296d85278cc9;p=platform%2Fcore%2Fsecurity%2Fklay.git

Add parsing netlink message header in netlink

This was moved from audit-trail by single resposibility principle.

Signed-off-by: Sungbae Yoo <sungbae.yoo@samsung.com>
Change-Id: I444326a5c42e1a254645a4042048b2a64bd96ea5
---

diff --git a/include/klay/netlink/netlink.h b/include/klay/netlink/netlink.h
index 9fdc648..a69c4d6 100644
--- a/include/klay/netlink/netlink.h
+++ b/include/klay/netlink/netlink.h
@@ -18,6 +18,7 @@
 #define __RUNTIME_NETLINK_NETLINK_H__
 
 #include <linux/netlink.h>
+#include <vector>
 
 #include <klay/klay.h>
 
@@ -29,6 +30,8 @@ namespace netlink {
 
 class KLAY_EXPORT Netlink final {
 public:
+	typedef std::pair<int, std::vector<char>> Message;
+
 	Netlink(int);
 	Netlink(Netlink&&);
 	Netlink(const Netlink&) = delete;
@@ -36,8 +39,8 @@ public:
 
 	Netlink& operator=(const Netlink&) = delete;
 
-	void send(const void *data, unsigned int size);
-	void recv(void *data, unsigned int size, int options = 0);
+	void send(int type, const std::vector<char>& data);
+	Message recv(int options = 0);
 
 	int getFd() const {
 		return fd;
@@ -45,6 +48,7 @@ public:
 
 private:
 	int fd;
+	unsigned int sequence;
 };
 
 } // namespace runtime
diff --git a/src/netlink/netlink.cpp b/src/netlink/netlink.cpp
index 9f4fdd7..e058c35 100644
--- a/src/netlink/netlink.cpp
+++ b/src/netlink/netlink.cpp
@@ -26,7 +26,8 @@
 
 namespace netlink {
 
-Netlink::Netlink(int protocol)
+Netlink::Netlink(int protocol) :
+	sequence(1)
 {
 	fd = ::socket(PF_NETLINK, SOCK_RAW, protocol);
 	if (fd < 0) {
@@ -40,7 +41,7 @@ Netlink::Netlink(int protocol)
 }
 
 Netlink::Netlink(Netlink&& netlink) :
-	fd(netlink.fd)
+	fd(netlink.fd), sequence(netlink.sequence)
 {
 	netlink.fd = -1;
 }
@@ -52,7 +53,7 @@ Netlink::~Netlink()
 	}
 }
 
-void Netlink::send(const void *buf, unsigned int size)
+void Netlink::send(int type, const std::vector<char>& data)
 {
 	struct sockaddr_nl addr;
 	int ret;
@@ -62,38 +63,83 @@ void Netlink::send(const void *buf, unsigned int size)
 	addr.nl_pid = 0;
 	addr.nl_groups = 0;
 
+	char buf[NLMSG_SPACE(data.size())];
+	auto *nlh = (struct nlmsghdr *)buf;
+
+	::memset(nlh, 0, sizeof(*nlh));
+
+	nlh->nlmsg_len = sizeof(buf);
+	nlh->nlmsg_type = type;
+	nlh->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
+	nlh->nlmsg_seq = sequence++;
+
+	// overflow - The sequence of message from kernel is 0,
+	// so this is not to use 0 as a sequence number.
+	if (sequence == 0)
+		sequence++;
+
+	::memcpy(NLMSG_DATA(buf), data.data(), data.size());
+
+
 	do {
-		ret = ::sendto(fd, buf, size, 0,
+		ret = ::sendto(fd, buf, sizeof(buf), 0,
 						(struct sockaddr*)&addr, sizeof(addr));
 	} while (ret < 0 && errno == EINTR);
 
 	if (ret < 0) {
-		throw runtime::Exception("Failed to send audit packet");
+		throw runtime::Exception("Failed to send a netlink message");
+	}
+
+	if (recv(MSG_PEEK).first == NLMSG_ERROR) {
+		auto reply = recv().second;
+		auto err = (struct nlmsgerr*)reply.data();
+		if (err->error)
+			throw runtime::Exception("Netlink error: " +
+										std::to_string(err->error));
+	} else {
+			throw runtime::Exception("Missing ack of netlink message");
 	}
 }
 
-void Netlink::recv(void *buf, unsigned int size, int options)
+Netlink::Message Netlink::recv(int options)
 {
-	struct sockaddr_nl nladdr;
-	socklen_t nladdrlen = sizeof(nladdr);
 	int ret;
 
+	//To get message size
+	struct nlmsghdr nlh;
 	do {
-		ret = ::recvfrom(fd, buf, size, options,
+		ret = ::recv(fd, &nlh, sizeof(nlh), options | MSG_PEEK);
+	} while (ret < 0 && errno == EINTR);
+
+	if (ret < 0) {
+		throw runtime::Exception("Failed to get the size of netlink message");
+	}
+
+	struct sockaddr_nl nladdr;
+	socklen_t nladdrlen = sizeof(nladdr);
+	char buf[nlh.nlmsg_len + NLMSG_HDRLEN];
+	do {
+		ret = ::recvfrom(fd, buf, sizeof(buf), options,
 							(struct sockaddr*)&nladdr, &nladdrlen);
 	} while (ret < 0 && errno == EINTR);
 
+	Message msg = {nlh.nlmsg_type, std::vector<char>(nlh.nlmsg_len)};
+
+	::memcpy(msg.second.data(), NLMSG_DATA(buf), msg.second.size());
+
 	if (ret < 0) {
 		throw runtime::Exception("Failed to receive audit packet");
 	}
 
 	if (nladdrlen != sizeof(nladdr)) {
-		throw runtime::Exception("Bad address size reading audit netlink socket");
+		throw runtime::Exception("Bad address size in netlink socket");
 	}
 
 	if (nladdr.nl_pid) {
-		throw runtime::Exception("Spoofed packet received on audit netlink socket");
+		throw runtime::Exception("Spoofed packet received on netlink socket");
 	}
+
+	return msg;
 }
 
 } // namespace runtime