1 #include <linux/slab.h> 2 #include <linux/types.h> 3 #include <linux/mm.h> 4 #include <linux/fs.h> 5 #include <linux/miscdevice.h> 6 #include <linux/module.h> 7 #include <linux/capability.h> 8 9 #include <xen/xen.h> 10 #include <xen/page.h> 11 #include <xen/xenbus_dev.h> 12 13 #include "xenbus_comms.h" 14 15 MODULE_LICENSE("GPL"); 16 17 static int xenbus_backend_open(struct inode *inode, struct file *filp) 18 { 19 if (!capable(CAP_SYS_ADMIN)) 20 return -EPERM; 21 22 return nonseekable_open(inode, filp); 23 } 24 25 static long xenbus_backend_ioctl(struct file *file, unsigned int cmd, unsigned long data) 26 { 27 if (!capable(CAP_SYS_ADMIN)) 28 return -EPERM; 29 30 switch (cmd) { 31 case IOCTL_XENBUS_BACKEND_EVTCHN: 32 if (xen_store_evtchn > 0) 33 return xen_store_evtchn; 34 return -ENODEV; 35 36 default: 37 return -ENOTTY; 38 } 39 } 40 41 static int xenbus_backend_mmap(struct file *file, struct vm_area_struct *vma) 42 { 43 size_t size = vma->vm_end - vma->vm_start; 44 45 if (!capable(CAP_SYS_ADMIN)) 46 return -EPERM; 47 48 if ((size > PAGE_SIZE) || (vma->vm_pgoff != 0)) 49 return -EINVAL; 50 51 if (remap_pfn_range(vma, vma->vm_start, 52 virt_to_pfn(xen_store_interface), 53 size, vma->vm_page_prot)) 54 return -EAGAIN; 55 56 return 0; 57 } 58 59 const struct file_operations xenbus_backend_fops = { 60 .open = xenbus_backend_open, 61 .mmap = xenbus_backend_mmap, 62 .unlocked_ioctl = xenbus_backend_ioctl, 63 }; 64 65 static struct miscdevice xenbus_backend_dev = { 66 .minor = MISC_DYNAMIC_MINOR, 67 .name = "xen/xenbus_backend", 68 .fops = &xenbus_backend_fops, 69 }; 70 71 static int __init xenbus_backend_init(void) 72 { 73 int err; 74 75 if (!xen_initial_domain()) 76 return -ENODEV; 77 78 err = misc_register(&xenbus_backend_dev); 79 if (err) 80 printk(KERN_ERR "Could not register xenbus backend device\n"); 81 return err; 82 } 83 84 static void __exit xenbus_backend_exit(void) 85 { 86 misc_deregister(&xenbus_backend_dev); 87 } 88 89 module_init(xenbus_backend_init); 90 module_exit(xenbus_backend_exit); 91