Makefile0100664000175300003300000000032010255632030011473 0ustar jillljeditifneq ($(KERNELRELEASE),) obj-m := ftp.o else KDIR := /lib/modules/2.6.9/build PWD := $(shell pwd) default: $(MAKE) -C $(KDIR) SUBDIRS=$(PWD) modules endif clean: rm -f *.o *.ko *.mod.c README0100664000175300003300000000244610255631755010743 0ustar jillljeditDirectory contents / |----> ftp.c -- Main kernel module |----> ftp.h -- Common header file declaring the params structure |----> do_ftp.c -- User space program `----> Makefile -- Makefile for compiling with 2.6 kernels. You need to have a compiled kernel source to build the module Usage As a normal user make gcc do_ftp.c As root insmod ftp.ko ./a.out rmmod ftp.ko Sample transcript for downloading the README file from ibiblio.org ------------------------------------------------------------------------------ $ make make -C /lib/modules/2.6.9/build SUBDIRS=/home/ppadala/ftp modules make[1]: Entering directory `/home/ppadala/linux-2.6.9' CC [M] /home/ppadala/ftp/ftp.o Building modules, stage 2. MODPOST CC /home/ppadala/ftp/ftp.mod.o LD [M] /home/ppadala/ftp/ftp.ko make[1]: Leaving directory `/home/ppadala/linux-2.6.9' $ gcc do_ftp.c $ su Password: # insmod ftp.ko # ./a.out 152.2.210.80 /README /tmp/README anonymous anon@cs.edu Connection from 152.2.210.80 return = 215 (length of file copied) # rmmod ftp.ko ------------------------------------------------------------------------------ do_ftp.c0100664000175300003300000000202010255611423011454 0ustar jillljedit#include #include #include #include #define __NR_my_sys_call 223 #include "ftp.h" _syscall1(long long int, my_sys_call, struct params *, p); unsigned char *getip(char *); int main(int argc, char **argv) { int i; long long r = -1; struct params pm; if (argc != 7) { fprintf(stderr, "usage: %s src filename> \n", argv[0]); exit(-1); } strncpy(pm.srcip,getip(argv[1]),4); strncpy(pm.destip,getip(argv[2]),4); strcpy(pm.src, argv[3]); strcpy(pm.dst, argv[4]); strcpy(pm.user, argv[5]); strcpy(pm.pass, argv[6]); r = my_sys_call(&pm); printf("return = %d (length of file copied)\n", r); return 0; } unsigned char *getip(char *s) { unsigned char *str; unsigned char *ip; int i = 0; ip = (unsigned char *) calloc(4,sizeof(unsigned char)); str = strtok(s,"."); ip[i] = atoi(str); ++i; while(str = strtok(NULL,".")) { ip[i] = atoi(str); ++i; } return ip; } ftp.c0100664000175300003300000001721010255632133011002 0ustar jillljedit#include /* For module_init and module_clea */ #include /* Needed by all modules */ #include /* Needed for KERN_ALERT */ /* For socket etc */ #include #include #include #include #include #include #include #include #include /* for kmalloc */ #define FTP_STRING "FTP_CLIENT: " #define PORT 21 /* FTP port */ #define EPH_PORT 2000 /* Ephemeral port for client */ #define SNDBUF 4096 #define RCVBUF 4096 #include "ftp.h" /* A simple function to convert the address from familiar * 4 part form to a 32-bit number */ u32 create_address(u8 *ip) { u32 addr = 0; int i; for(i = 0;i < 4;++i) { addr += ip[i]; if(i == 3) break; addr <<= 8; } return addr; } int send_sync_buf (struct socket *sock, const char *buf, const size_t length, unsigned long flags) { struct msghdr msg; struct iovec iov; int len, written = 0, left = length; mm_segment_t oldmm; msg.msg_name = 0; msg.msg_namelen = 0; msg.msg_iov = &iov; msg.msg_iovlen = 1; msg.msg_control = NULL; msg.msg_controllen = 0; msg.msg_flags = flags; oldmm = get_fs(); set_fs(KERNEL_DS); repeat_send: msg.msg_iov->iov_len = left; msg.msg_iov->iov_base = (char *) buf + written; len = sock_sendmsg(sock, &msg, left); if ((len == -ERESTARTSYS) || (!(flags & MSG_DONTWAIT) && (len == -EAGAIN))) goto repeat_send; if (len > 0) { written += len; left -= len; if (left) goto repeat_send; } set_fs(oldmm); return written ? written : len; } void send_reply(struct socket *sock, char *str) { send_sync_buf(sock, str, strlen(str), MSG_DONTWAIT); } int read_response(struct socket *sock, char *str) { mm_segment_t oldmm; struct msghdr msg; struct iovec iov; int len; int max_size = SNDBUF; msg.msg_name = 0; msg.msg_namelen = 0; msg.msg_iov = &iov; msg.msg_iovlen = 1; msg.msg_control = NULL; msg.msg_controllen = 0; msg.msg_flags = 0; msg.msg_iov->iov_base = str; msg.msg_iov->iov_len = max_size; oldmm = get_fs(); set_fs(KERNEL_DS); read_again: len = sock_recvmsg(sock, &msg, max_size, 0); /*MSG_DONTWAIT); */ if (len == -EAGAIN || len == -ERESTARTSYS) { goto read_again; } set_fs(oldmm); return len; } int write_to_file(char *fname, struct socket *sock, char *response) { struct file *f = NULL; int flags, total_written; mm_segment_t oldmm; int len; flags = O_CREAT | O_WRONLY | O_TRUNC; if(!fname) return -1; f = filp_open(fname, flags, 0600); if (!f || !f->f_op || !f->f_op->write) { printk(KERN_ERR "WARNING: File (write) object is a null pointer!!!\n"); return -1; } f->f_pos = 0; oldmm = get_fs(); set_fs(KERNEL_DS); total_written = 0; while((len = read_response(sock, response)) > 0) { if(signal_pending(current)) { printk(KERN_INFO FTP_STRING "Got a signal\n"); total_written = -ERESTARTSYS; break; } len = f->f_op->write(f, response, len, &f->f_pos); total_written += len; } set_fs(oldmm); if (f->f_op && f->f_op->flush) { lock_kernel(); f->f_op->flush(f); unlock_kernel(); } fput(f); printk(KERN_INFO FTP_STRING "Wrote %d bytes\n", total_written); return total_written; } extern void *sys_call_table[]; asmlinkage long sys_ni_syscall(void) { return -ENOSYS; } asmlinkage int my_sys_call(struct params __user *pm) { struct sockaddr_in saddr, daddr; struct socket *control= NULL; struct socket *data = NULL; struct socket *new_sock = NULL; int r = -1; char *response = kmalloc(SNDBUF, GFP_KERNEL); char *reply = kmalloc(RCVBUF, GFP_KERNEL); char *a, *p; char address[128]; int len = 0, total_written = 0; char temp[64]; struct params pmk; if(unlikely(!access_ok(VERIFY_READ, pm, sizeof(pm)))) return -EFAULT; if(copy_from_user(&pmk, pm, sizeof(struct params))) return -EFAULT; if(current->uid != 0) return r; r = sock_create(PF_INET, SOCK_STREAM, IPPROTO_TCP, &control); if (r < 0) { printk(KERN_ERR FTP_STRING "error %d creating socket.\n", r); goto err; } memset(&saddr,0, sizeof(saddr)); saddr.sin_family = AF_INET; saddr.sin_port = htons(PORT); saddr.sin_addr.s_addr = htonl(create_address(pmk.destip)); r = control->ops->connect(control, (struct sockaddr *) &saddr, sizeof(saddr), O_RDWR); if (r && (r != -EINPROGRESS)) { printk(KERN_ERR FTP_STRING "connect error: %d\n", r); goto err; } read_response(control, response); sprintf(temp, "USER %s\r\n", pmk.user); send_reply(control, temp); read_response(control, response); sprintf(temp, "PASS %s\r\n", pmk.pass); send_reply(control, temp); read_response(control, response); r = sock_create(PF_INET, SOCK_STREAM, IPPROTO_TCP, &data); if (r < 0) { printk(KERN_ERR FTP_STRING "error %d creating data socket.\n", r); goto err1; } memset(&daddr,0, sizeof(daddr)); daddr.sin_family = AF_INET; daddr.sin_port = htons(EPH_PORT); daddr.sin_addr.s_addr= htonl(create_address(pmk.srcip)); r = data->ops->bind(data, (struct sockaddr *)&daddr, sizeof (daddr)); if(r < 0) { printk(KERN_ERR FTP_STRING "error %d binding data socket.\n", r); goto err2; } r = data->ops->listen(data, 1); if(r < 0) { printk(KERN_ERR FTP_STRING "error %d listening in data socket.\n", r); goto err2; } a = (char *)&daddr.sin_addr; p = (char *)&daddr.sin_port; #define UC(b) (((int)b)&0xff) sprintf(reply, "PORT %d,%d,%d,%d,%d,%d\r\n", UC(a[0]), UC(a[1]), UC(a[2]), UC(a[3]), UC(p[0]), UC(p[1])); printk(KERN_INFO FTP_STRING "Sending PORT command: %s\n", reply); send_reply(control, reply); read_response(control, response); strcpy(reply, "RETR "); strcat(reply, pmk.src); strcat(reply, "\r\n"); send_reply(control, reply); read_response(control, response); new_sock = sock_alloc(); if (!new_sock) goto err2; new_sock->type = data->type; new_sock->ops = data->ops; r = data->ops->accept(data, new_sock, 0); if (r < 0) { printk("Error accepting connection on data socket\n"); goto err3; } new_sock->ops->getname(new_sock, (struct sockaddr *)address, &len, 2); a = (char *)&(((struct sockaddr_in *)address)->sin_addr.s_addr); printk("Connection from %d.%d.%d.%d\n", UC(a[0]), UC(a[1]), UC(a[2]), UC(a[3])); if((total_written = write_to_file(pmk.dst, new_sock, response)) < 0) goto err3; sock_release(new_sock); sock_release(data); sock_release(control); return total_written; err3: sock_release(new_sock); err2: sock_release(data); err1: sock_release(control); err: return -1; } static int ftp_init(void) { printk(KERN_INFO FTP_STRING "Starting ftp client module\n"); sys_call_table[223] = my_sys_call; return 0; } static void ftp_exit(void) { printk(KERN_INFO FTP_STRING "Cleaning up ftp client module, bye !\n"); sys_call_table[223] = sys_ni_syscall; } module_init(ftp_init); module_exit(ftp_exit); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Pradeep Padala"); ftp.h0100664000175300003300000000030110255607746011014 0ustar jillljedit#ifndef __FTP_H #define __FTP_H struct params { unsigned char destip[4]; unsigned char srcip[4]; char src[64]; char dst[64]; char user[16]; char pass[64]; }; #endif