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 9fdc648d43dc2db80dca2ff4269c937863a38577..a69c4d6aab4d689908aee4dc8b7fe0411210320e 100644 (file)
--- 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 9f4fdd789a5df7c39f0596459db2d8c668c25c65..e058c352030de82e813aaef814bba9492092000d 100644 (file)
--- 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