求助,netlink传输,内核死活收不到包

overcloud

谢谢各位的帮助，代码改了一下现在可以从userspace像kernel发送并且成功收到了，但是kernel返回的消息userspace还是收不到，recvmsg 一直返回 0

内核代码如下:

#include <linux/init.h> #include <linux/module.h> #include <linux/version.h> #include <linux/skbuff.h> #include <linux/kernel.h> #include <linux/errno.h> #include <net/sock.h> #include <linux/types.h> #include <linux/socket.h> #include <linux/netlink.h> #define MAX_PAYLOAD 1024 struct sock *nl_sk = NULL; u32 pid = 0; void nl_data_ready (struct sk_buff *skb) {&nbsp;&nbsp;&nbsp;&nbsp;struct sk_buff *skb2 = NULL; &nbsp;&nbsp;&nbsp;&nbsp;printk("input()called\n"); &nbsp;&nbsp;&nbsp;&nbsp;struct nlmsghdr *nlh = NULL; &nbsp;&nbsp;&nbsp;&nbsp;nlh = (struct nlmsghdr *)skb->data; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;printk("%s: received netlink message payload:%s\n", &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;__FUNCTION__, NLMSG_DATA(nlh)); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;pid = nlh->nlmsg_pid; &nbsp;&nbsp;&nbsp;&nbsp;printk("pid = %d\n",pid); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;if(pid !=0){ &nbsp;&nbsp;&nbsp;&nbsp;skb2 = alloc_skb(NLMSG_SPACE(MAX_PAYLOAD),GFP_KERNEL); &nbsp;&nbsp;&nbsp;&nbsp;printk("skb allocated\n"); &nbsp;&nbsp;&nbsp;&nbsp;nlh = (struct nlmsghdr *)skb2->data; &nbsp;&nbsp;&nbsp;&nbsp;nlh->nlmsg_len = NLMSG_SPACE(MAX_PAYLOAD); &nbsp;&nbsp;&nbsp;&nbsp;nlh->nlmsg_pid = 0; &nbsp;&nbsp;&nbsp;&nbsp;nlh->nlmsg_flags = 0; &nbsp;&nbsp;&nbsp;&nbsp;strcpy(NLMSG_DATA(nlh),"Greeting From Kernel!"); &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;NETLINK_CB(skb2).pid = 0; &nbsp;&nbsp;&nbsp;&nbsp;NETLINK_CB(skb2).dst_group = 0; &nbsp;&nbsp;&nbsp;&nbsp;printk("ready to unicast\n"); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;if(netlink_unicast(nl_sk, skb2, pid, MSG_DONTWAIT)<0) &nbsp;&nbsp;&nbsp;&nbsp;printk("error unicast\n"); &nbsp;&nbsp;&nbsp;&nbsp;else printk("unicasted to pid:%u \n",pid); &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;}//endif &nbsp;&nbsp; } void netlink_test(){ &nbsp; &nbsp; &nbsp;//struct net net1; &nbsp;nl_sk = netlink_kernel_create(&init_net,25,0, &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;nl_data_ready,NULL,THIS_MODULE); &nbsp;if(nl_sk<0) &nbsp;&nbsp;&nbsp;&nbsp;printk("error create sock\n"); &nbsp;else printk("successful create socket\n"); &nbsp; } static int my_module_init(void){ &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;printk(KERN_INFO "initializing Netlink Socket!\n"); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;netlink_test(); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return 0; } static void netlink_clear(void) {&nbsp;&nbsp;&nbsp;&nbsp; sock_release(nl_sk->sk_socket); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;printk(KERN_INFO"GOod Bye!\n"); } module_init(my_module_init); module_exit(netlink_clear);

userspace代码如下

#include <sys/socket.h> #include <linux/netlink.h> #include <iostream> //#include <sys/socket.h> #include <linux/types.h> //#include <linux/netlink.h> #include <stdio.h> #include <string.h> #include <unistd.h> #include <stdlib.h> #include <errno.h> using namespace std; #define MAX_PAYLOAD 1024  /* maximum payload size*/ struct sockaddr_nl src_addr, dest_addr; struct nlmsghdr *nlh = NULL; struct iovec iov; struct msghdr msg; int main(){ std::cout<<("error bind")<<std::endl; int sock_fd = socket(PF_NETLINK, SOCK_RAW,25); if (sock_fd <0) std::cout<<("error create socket!")<<std::endl; memset(&src_addr, 0, sizeof(src_addr)); src_addr.nl_family = AF_NETLINK;      src_addr.nl_pid = getpid();  /* self pid */ src_addr.nl_groups = 0;  /* not in mcast groups */ if (bind(sock_fd, (struct sockaddr*)&src_addr,sizeof(src_addr))<0)         std::cout<<("error bind")<<std::endl; else std::cout<<("binded")<<std::endl; memset(&dest_addr, 0, sizeof(dest_addr)); dest_addr.nl_family = AF_NETLINK; dest_addr.nl_pid = 0;   /* For Linux Kernel */ dest_addr.nl_groups = 0; /* unicast */ nlh=(struct nlmsghdr *)malloc(                          NLMSG_SPACE(MAX_PAYLOAD)); /* Fill the netlink message header */ nlh->nlmsg_len = NLMSG_SPACE(MAX_PAYLOAD); nlh->nlmsg_pid = getpid();  /* self pid */ nlh->nlmsg_flags = 0; /* Fill in the netlink message payload */ strcpy((char *)NLMSG_DATA(nlh), "Hello you!"); iov.iov_base = (void *)nlh; iov.iov_len = nlh->nlmsg_len; printf("%d\n",iov.iov_len); msg.msg_name = (void *)&dest_addr; msg.msg_namelen = sizeof(dest_addr); msg.msg_iov = &iov; msg.msg_iovlen = 1; if(sendmsg(sock_fd, &msg, 0) == -1){         std::cout<<("error send")<<errno<<std::endl; } else std::cout<<("sent")<<std::endl; memset(nlh, 0, NLMSG_SPACE(MAX_PAYLOAD)); printf("nlh set to be %s\n",NLMSG_DATA(nlh)); int ret = recvmsg(sock_fd, &msg, 0); if( ret < 0)         std::cout<<("error recv")<<errno<<std::endl; else std::cout<<("received")<<ret<<std::endl; printf("Received message payload:%s\n from kernel, length is %d\n",(char *)(NLMSG_DATA(nlh)),nlh->nlmsg_len);     /* Close Netlink Socket */ close(sock_fd); }

[ 本帖最后由 overcloud 于 2009-2-27 16:39 编辑 ]

overcloud

新的内核 netlink_kernel_create变成了下面的定义,谁知道struct net这里怎么用?
extern struct sock *netlink_kernel_create(struct net *net,
                                          int unit,unsigned int groups,
                                          void (*input)(struct sk_buff *skb),
                                          struct mutex *cb_mutex,
                                          struct module *module);

overcloud

原帖由 duanjigang 于 2009-2-22 22:40 发表
参考一个入门的例子修改下。
参考此文：
http://bbs3.chinaunix.net/viewthread.php?tid=1274437

就是参照这些文档写的,但是新的kernel很多api变了,实在是搞不定,谁能帮着看下?

overcloud

。。

[ 本帖最后由 overcloud 于 2009-2-27 16:40 编辑 ]

overcloud

顶一下

overcloud

原帖由 fly6 于 2009-2-25 10:12 发表
你定义的RAW SOCKET ID号为25,内核其他地方有没有占用

你好,肯定没被占用,netlink.h里面才到20好像,我之前用netlink_firewall也是一样这种情况

overcloud

谢谢各位的帮助，现在有了进展了，netlink_kernel_create搞定了，kernel显示收到内容了，但是从kernel unicast出去的msg用户态还是一直收不到，谁再帮着看看

overcloud

原帖由 Godbach 于 2009-2-27 17:27 发表


kernel unicast好像是要制定用户态的ID号的，这个地方指定了没有。

恩，
这个我在userspace用getpid()获得了然后通过第一个从userspace发到kernel的消息里传给了内核
在内核代码里
pid = nlh->nlmsg_pid;
然后再用netlink_unicast的阿

overcloud

dmesg显示是
[185112.322833] initializing Netlink Socket!
[185112.322851] successful create socket
[185118.182413] input()called
[185118.182428] nl_data_ready: received netlink message payload:Hello you!
[185118.182433] pid = 18160
[185118.182437] skb allocated
[185118.182441] Greeting From Kernel!
[185118.182444] ready to unicast
[185118.182451] unicasted
应该就是成功发出去了吧

overcloud

原帖由 Godbach 于 2009-2-27 17:50 发表
ip_queue中向用户空间发送信息的函数：

其中红色那行代码就是实际的发送函数，这个函数里面peer_pid参数为用户空间发送消息是记录下来的，你比较一下是否是在内核接受用户消息时记录下来的。

我看ip_queue.c里面并没有设置NETLINK_CB(skb),所以我把那两行去掉了,直接netlink_unicast,这次好像收到了,但是马上就机器崩溃,好像close(sock)那里出问题了,或者别的地方...依然一头雾水