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← Revision 5 as of 2017-12-30 01:30:34 ⇥
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First of all, if you are playing with Linux 2.4, see at http://br.kernelnewbies.org/docs/modulos_guia.html#threads, where can be found a clear example on how to use kernel threads and sockets in kernel 2.4 | First of all, if you are hacking Linux 2.4, see at http://br.kernelnewbies.org/docs/modulos_guia.html#threads, where can be found a good example on how to use kernel threads and sockets in 2.4 series |
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The code for the client is not provided, please, if you have one post it! ;) (please inform to topi@phreaker.net if you found a bug on it) |
'''Aknowledgments''' *Rodrigo Rubira Branco <rodrigo@kernelhacking.com> for fixes, ''ksocket_send'' function (so the kernel module can act as a server and client) (report bugs to topi@phreaker.net) |
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#if CONFIG_MODVERSIONS==1 #define MODVERSIONS #include <config/modversions.h> #endif |
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#define CONNECT_PORT 23 | |
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//#define INADDR_SEND ((unsigned long int)0x7f000001) /* 127.0.0.1 */ #define INADDR_SEND INADDR_LOOPBACK /* 2006/06/27 - Added ksocket_send, so, after receive a packet, the kernel send another back to the CONNECT_PORT - Rodrigo Rubira Branco <rodrigo@kernelhacking.com> 2006/05/14 - Initial version - Toni Garcia-Navarro <topi@phreaker.net> */ |
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struct task_struct *thread; struct socket *sock; struct sockaddr_in addr; int running; |
struct task_struct *thread; struct socket *sock; struct sockaddr_in addr; struct socket *sock_send; struct sockaddr_in addr_send; int running; |
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struct kthread_t *kthread = NULL; |
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struct socket *sock; struct kthread_t *kthread = NULL; |
int ksocket_send(struct socket *sock, struct sockaddr_in *addr, unsigned char *buf, int len); |
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int size, err; int bufsize = 1024; unsigned char buf[bufsize]; /* kernel thread initialization */ lock_kernel(); kthread->running = 1; current->flags |= PF_NOFREEZE; /* daemonize (take care with signals, after daemonize() they are disabled) */ daemonize(MODULE_NAME); allow_signal(SIGKILL); unlock_kernel(); /* create a socket */ if ((err = sock_create(AF_INET, SOCK_DGRAM, IPPROTO_UDP, &kthread->sock)) < 0) { printk(KERN_INFO MODULE_NAME": Could not create a datagram socket, error = %d\n", -ENXIO); goto out; } memset(&kthread->addr, 0, sizeof(struct sockaddr)); kthread->addr.sin_family = AF_INET; kthread->addr.sin_addr.s_addr = htonl(INADDR_ANY); kthread->addr.sin_port = htons(DEFAULT_PORT); if ((err = kthread->sock->ops->bind(kthread->sock, (struct sockaddr *)&kthread->addr, sizeof(struct sockaddr))) < 0) { printk(KERN_INFO MODULE_NAME": Could not bind to socket, error = %d\n", -err); goto close_and_out; } //kthread->sock->sk->sk_family = AF_INET; printk(KERN_INFO MODULE_NAME": listening on port %d\n", DEFAULT_PORT); /* main loop */ for (;;) { memset(&buf, 0, bufsize); size = ksocket_receive(kthread->sock, &kthread->addr, buf, bufsize); if (signal_pending(current)) break; if (size < 0) printk(KERN_INFO MODULE_NAME": error getting datagram, sock_recvmsg error = %d\n", size); else { printk(KERN_INFO MODULE_NAME": received %d bytes\n", size); /* data processing */ } } |
int size, err; int bufsize = 10; unsigned char buf[bufsize+1]; /* kernel thread initialization */ lock_kernel(); kthread->running = 1; current->flags |= PF_NOFREEZE; /* daemonize (take care with signals, after daemonize() they are disabled) */ daemonize(MODULE_NAME); allow_signal(SIGKILL); unlock_kernel(); /* create a socket */ if ( ( (err = sock_create(AF_INET, SOCK_DGRAM, IPPROTO_UDP, &kthread->sock)) < 0) || ( (err = sock_create(AF_INET, SOCK_DGRAM, IPPROTO_UDP, &kthread->sock_send)) < 0 )) { printk(KERN_INFO MODULE_NAME": Could not create a datagram socket, error = %d\n", -ENXIO); goto out; } memset(&kthread->addr, 0, sizeof(struct sockaddr)); memset(&kthread->addr_send, 0, sizeof(struct sockaddr)); kthread->addr.sin_family = AF_INET; kthread->addr_send.sin_family = AF_INET; kthread->addr.sin_addr.s_addr = htonl(INADDR_ANY); kthread->addr_send.sin_addr.s_addr = htonl(INADDR_SEND); kthread->addr.sin_port = htons(DEFAULT_PORT); kthread->addr_send.sin_port = htons(CONNECT_PORT); if ( ( (err = kthread->sock->ops->bind(kthread->sock, (struct sockaddr *)&kthread->addr, sizeof(struct sockaddr) ) ) < 0) || (err = kthread->sock_send->ops->connect(kthread->sock_send, (struct sockaddr *)&kthread->addr_send, sizeof(struct sockaddr), 0) < 0 )) { printk(KERN_INFO MODULE_NAME": Could not bind or connect to socket, error = %d\n", -err); goto close_and_out; } printk(KERN_INFO MODULE_NAME": listening on port %d\n", DEFAULT_PORT); /* main loop */ for (;;) { memset(&buf, 0, bufsize+1); size = ksocket_receive(kthread->sock, &kthread->addr, buf, bufsize); if (signal_pending(current)) break; if (size < 0) printk(KERN_INFO MODULE_NAME": error getting datagram, sock_recvmsg error = %d\n", size); else { printk(KERN_INFO MODULE_NAME": received %d bytes\n", size); /* data processing */ printk("\n data: %s\n", buf); /* sending */ memset(&buf, 0, bufsize+1); strcat(buf, "testing..."); ksocket_send(kthread->sock_send, &kthread->addr_send, buf, strlen(buf)); } } |
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sock_release(kthread->sock); kthread->sock = NULL; |
sock_release(kthread->sock); sock_release(kthread->sock_send); kthread->sock = NULL; kthread->sock_send = NULL; |
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kthread->thread = NULL; kthread->running = 0; |
kthread->thread = NULL; kthread->running = 0; } int ksocket_send(struct socket *sock, struct sockaddr_in *addr, unsigned char *buf, int len) { struct msghdr msg; struct iovec iov; mm_segment_t oldfs; int size = 0; if (sock->sk==NULL) return 0; iov.iov_base = buf; iov.iov_len = len; msg.msg_flags = 0; msg.msg_name = addr; msg.msg_namelen = sizeof(struct sockaddr_in); msg.msg_control = NULL; msg.msg_controllen = 0; msg.msg_iov = &iov; msg.msg_iovlen = 1; msg.msg_control = NULL; oldfs = get_fs(); set_fs(KERNEL_DS); size = sock_sendmsg(sock,&msg,len); set_fs(oldfs); return size; |
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struct msghdr msg; struct iovec iov; mm_segment_t oldfs; int size = 0; if (sock->sk==NULL) return 0; iov.iov_base = buf; iov.iov_len = len; msg.msg_flags = 0; msg.msg_name = addr; msg.msg_namelen = sizeof(struct sockaddr_in); msg.msg_control = NULL; msg.msg_controllen = 0; msg.msg_iov = &iov; msg.msg_iovlen = 1; msg.msg_control = NULL; oldfs = get_fs(); set_fs(KERNEL_DS); size = sock_recvmsg(sock,&msg,len,msg.msg_flags); set_fs(oldfs); return size; |
struct msghdr msg; struct iovec iov; mm_segment_t oldfs; int size = 0; if (sock->sk==NULL) return 0; iov.iov_base = buf; iov.iov_len = len; msg.msg_flags = 0; msg.msg_name = addr; msg.msg_namelen = sizeof(struct sockaddr_in); msg.msg_control = NULL; msg.msg_controllen = 0; msg.msg_iov = &iov; msg.msg_iovlen = 1; msg.msg_control = NULL; oldfs = get_fs(); set_fs(KERNEL_DS); size = sock_recvmsg(sock,&msg,len,msg.msg_flags); set_fs(oldfs); return size; |
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kthread = kmalloc(sizeof(struct kthread_t), GFP_KERNEL); memset(kthread, 0, sizeof(struct kthread_t)); /* start kernel thread */ kthread->thread = kthread_run((void *)ksocket_start, NULL, MODULE_NAME); if (IS_ERR(kthread->thread)) { printk(KERN_INFO MODULE_NAME": unable to start kernel thread\n"); kfree(kthread); kthread = NULL; return -ENOMEM; } return 0; |
kthread = kmalloc(sizeof(struct kthread_t), GFP_KERNEL); memset(kthread, 0, sizeof(struct kthread_t)); /* start kernel thread */ kthread->thread = kthread_run((void *)ksocket_start, NULL, MODULE_NAME); if (IS_ERR(kthread->thread)) { printk(KERN_INFO MODULE_NAME": unable to start kernel thread\n"); kfree(kthread); kthread = NULL; return -ENOMEM; } return 0; |
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int err; if (kthread->thread==NULL) printk(KERN_INFO MODULE_NAME": no kernel thread to kill\n"); else { lock_kernel(); err = kill_proc(kthread->thread->pid, SIGKILL, 1); unlock_kernel(); /* wait for kernel thread to die */ if (err < 0) printk(KERN_INFO MODULE_NAME": unknown error %d while trying to terminate kernel thread\n",-err); else { while (kthread->running == 1) msleep(10); printk(KERN_INFO MODULE_NAME": succesfully killed kernel thread!\n"); } } /* free allocated resources before exit */ if (kthread->sock != NULL) { sock_release(kthread->sock); kthread->sock = NULL; } kfree(kthread); kthread = NULL; printk(KERN_INFO MODULE_NAME": module unloaded\n"); |
int err; if (kthread->thread==NULL) printk(KERN_INFO MODULE_NAME": no kernel thread to kill\n"); else { lock_kernel(); err = kill_proc(kthread->thread->pid, SIGKILL, 1); unlock_kernel(); /* wait for kernel thread to die */ if (err < 0) printk(KERN_INFO MODULE_NAME": unknown error %d while trying to terminate kernel thread\n",-err); else { while (kthread->running == 1) msleep(10); printk(KERN_INFO MODULE_NAME": succesfully killed kernel thread!\n"); } } /* free allocated resources before exit */ if (kthread->sock != NULL) { sock_release(kthread->sock); kthread->sock = NULL; } kfree(kthread); kthread = NULL; printk(KERN_INFO MODULE_NAME": module unloaded\n"); |
I've been playing for a while with sockets in kernel-space, that's the way i've found to have a kernel thread listening on a UDP port
Howto create a UDP Server in kernel-space (for Linux 2.6)
First of all, if you are hacking Linux 2.4, see at http://br.kernelnewbies.org/docs/modulos_guia.html#threads, where can be found a good example on how to use kernel threads and sockets in 2.4 series
In a second place, take into account that kernel-space servers are not the most desiderable thing you can do, user-space servers are prefered in almost every case.
Aknowledgments
Rodrigo Rubira Branco <rodrigo@kernelhacking.com> for fixes, ksocket_send function (so the kernel module can act as a server and client)
(report bugs to topi@phreaker.net)
#include <linux/kernel.h> #include <linux/module.h> #include <linux/init.h> #include <linux/kthread.h> #include <linux/errno.h> #include <linux/types.h> #include <linux/netdevice.h> #include <linux/ip.h> #include <linux/in.h> #include <linux/delay.h> #define DEFAULT_PORT 2325 #define CONNECT_PORT 23 #define MODULE_NAME "ksocket" //#define INADDR_SEND ((unsigned long int)0x7f000001) /* 127.0.0.1 */ #define INADDR_SEND INADDR_LOOPBACK /* 2006/06/27 - Added ksocket_send, so, after receive a packet, the kernel send another back to the CONNECT_PORT - Rodrigo Rubira Branco <rodrigo@kernelhacking.com> 2006/05/14 - Initial version - Toni Garcia-Navarro <topi@phreaker.net> */ struct kthread_t { struct task_struct *thread; struct socket *sock; struct sockaddr_in addr; struct socket *sock_send; struct sockaddr_in addr_send; int running; }; struct kthread_t *kthread = NULL; /* function prototypes */ int ksocket_receive(struct socket *sock, struct sockaddr_in *addr, unsigned char *buf, int len); int ksocket_send(struct socket *sock, struct sockaddr_in *addr, unsigned char *buf, int len); static void ksocket_start(void) { int size, err; int bufsize = 10; unsigned char buf[bufsize+1]; /* kernel thread initialization */ lock_kernel(); kthread->running = 1; current->flags |= PF_NOFREEZE; /* daemonize (take care with signals, after daemonize() they are disabled) */ daemonize(MODULE_NAME); allow_signal(SIGKILL); unlock_kernel(); /* create a socket */ if ( ( (err = sock_create(AF_INET, SOCK_DGRAM, IPPROTO_UDP, &kthread->sock)) < 0) || ( (err = sock_create(AF_INET, SOCK_DGRAM, IPPROTO_UDP, &kthread->sock_send)) < 0 )) { printk(KERN_INFO MODULE_NAME": Could not create a datagram socket, error = %d\n", -ENXIO); goto out; } memset(&kthread->addr, 0, sizeof(struct sockaddr)); memset(&kthread->addr_send, 0, sizeof(struct sockaddr)); kthread->addr.sin_family = AF_INET; kthread->addr_send.sin_family = AF_INET; kthread->addr.sin_addr.s_addr = htonl(INADDR_ANY); kthread->addr_send.sin_addr.s_addr = htonl(INADDR_SEND); kthread->addr.sin_port = htons(DEFAULT_PORT); kthread->addr_send.sin_port = htons(CONNECT_PORT); if ( ( (err = kthread->sock->ops->bind(kthread->sock, (struct sockaddr *)&kthread->addr, sizeof(struct sockaddr) ) ) < 0) || (err = kthread->sock_send->ops->connect(kthread->sock_send, (struct sockaddr *)&kthread->addr_send, sizeof(struct sockaddr), 0) < 0 )) { printk(KERN_INFO MODULE_NAME": Could not bind or connect to socket, error = %d\n", -err); goto close_and_out; } printk(KERN_INFO MODULE_NAME": listening on port %d\n", DEFAULT_PORT); /* main loop */ for (;;) { memset(&buf, 0, bufsize+1); size = ksocket_receive(kthread->sock, &kthread->addr, buf, bufsize); if (signal_pending(current)) break; if (size < 0) printk(KERN_INFO MODULE_NAME": error getting datagram, sock_recvmsg error = %d\n", size); else { printk(KERN_INFO MODULE_NAME": received %d bytes\n", size); /* data processing */ printk("\n data: %s\n", buf); /* sending */ memset(&buf, 0, bufsize+1); strcat(buf, "testing..."); ksocket_send(kthread->sock_send, &kthread->addr_send, buf, strlen(buf)); } } close_and_out: sock_release(kthread->sock); sock_release(kthread->sock_send); kthread->sock = NULL; kthread->sock_send = NULL; out: kthread->thread = NULL; kthread->running = 0; } int ksocket_send(struct socket *sock, struct sockaddr_in *addr, unsigned char *buf, int len) { struct msghdr msg; struct iovec iov; mm_segment_t oldfs; int size = 0; if (sock->sk==NULL) return 0; iov.iov_base = buf; iov.iov_len = len; msg.msg_flags = 0; msg.msg_name = addr; msg.msg_namelen = sizeof(struct sockaddr_in); msg.msg_control = NULL; msg.msg_controllen = 0; msg.msg_iov = &iov; msg.msg_iovlen = 1; msg.msg_control = NULL; oldfs = get_fs(); set_fs(KERNEL_DS); size = sock_sendmsg(sock,&msg,len); set_fs(oldfs); return size; } int ksocket_receive(struct socket* sock, struct sockaddr_in* addr, unsigned char* buf, int len) { struct msghdr msg; struct iovec iov; mm_segment_t oldfs; int size = 0; if (sock->sk==NULL) return 0; iov.iov_base = buf; iov.iov_len = len; msg.msg_flags = 0; msg.msg_name = addr; msg.msg_namelen = sizeof(struct sockaddr_in); msg.msg_control = NULL; msg.msg_controllen = 0; msg.msg_iov = &iov; msg.msg_iovlen = 1; msg.msg_control = NULL; oldfs = get_fs(); set_fs(KERNEL_DS); size = sock_recvmsg(sock,&msg,len,msg.msg_flags); set_fs(oldfs); return size; } int __init ksocket_init(void) { kthread = kmalloc(sizeof(struct kthread_t), GFP_KERNEL); memset(kthread, 0, sizeof(struct kthread_t)); /* start kernel thread */ kthread->thread = kthread_run((void *)ksocket_start, NULL, MODULE_NAME); if (IS_ERR(kthread->thread)) { printk(KERN_INFO MODULE_NAME": unable to start kernel thread\n"); kfree(kthread); kthread = NULL; return -ENOMEM; } return 0; } void __exit ksocket_exit(void) { int err; if (kthread->thread==NULL) printk(KERN_INFO MODULE_NAME": no kernel thread to kill\n"); else { lock_kernel(); err = kill_proc(kthread->thread->pid, SIGKILL, 1); unlock_kernel(); /* wait for kernel thread to die */ if (err < 0) printk(KERN_INFO MODULE_NAME": unknown error %d while trying to terminate kernel thread\n",-err); else { while (kthread->running == 1) msleep(10); printk(KERN_INFO MODULE_NAME": succesfully killed kernel thread!\n"); } } /* free allocated resources before exit */ if (kthread->sock != NULL) { sock_release(kthread->sock); kthread->sock = NULL; } kfree(kthread); kthread = NULL; printk(KERN_INFO MODULE_NAME": module unloaded\n"); } /* init and cleanup functions */ module_init(ksocket_init); module_exit(ksocket_exit); /* module information */ MODULE_DESCRIPTION("kernel thread listening on a UDP socket (code example)"); MODULE_AUTHOR("Toni Garcia-Navarro <topi@phreaker.net>"); MODULE_LICENSE("GPL");