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Linux/fs/coda/psdev.c

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  1 // SPDX-License-Identifier: GPL-2.0-or-later
  2 /*
  3  *              An implementation of a loadable kernel mode driver providing
  4  *              multiple kernel/user space bidirectional communications links.
  5  *
  6  *              Author:         Alan Cox <alan@lxorguk.ukuu.org.uk>
  7  * 
  8  *              Adapted to become the Linux 2.0 Coda pseudo device
  9  *              Peter  Braam  <braam@maths.ox.ac.uk> 
 10  *              Michael Callahan <mjc@emmy.smith.edu>           
 11  *
 12  *              Changes for Linux 2.1
 13  *              Copyright (c) 1997 Carnegie-Mellon University
 14  */
 15 
 16 #include <linux/module.h>
 17 #include <linux/errno.h>
 18 #include <linux/kernel.h>
 19 #include <linux/major.h>
 20 #include <linux/time.h>
 21 #include <linux/sched/signal.h>
 22 #include <linux/slab.h>
 23 #include <linux/ioport.h>
 24 #include <linux/fcntl.h>
 25 #include <linux/delay.h>
 26 #include <linux/skbuff.h>
 27 #include <linux/proc_fs.h>
 28 #include <linux/vmalloc.h>
 29 #include <linux/fs.h>
 30 #include <linux/file.h>
 31 #include <linux/poll.h>
 32 #include <linux/init.h>
 33 #include <linux/list.h>
 34 #include <linux/mutex.h>
 35 #include <linux/device.h>
 36 #include <linux/pid_namespace.h>
 37 #include <asm/io.h>
 38 #include <linux/uaccess.h>
 39 
 40 #include <linux/coda.h>
 41 #include "coda_psdev.h"
 42 #include "coda_linux.h"
 43 
 44 #include "coda_int.h"
 45 
 46 /* statistics */
 47 int           coda_hard;         /* allows signals during upcalls */
 48 unsigned long coda_timeout = 30; /* .. secs, then signals will dequeue */
 49 
 50 
 51 struct venus_comm coda_comms[MAX_CODADEVS];
 52 static struct class *coda_psdev_class;
 53 
 54 /*
 55  * Device operations
 56  */
 57 
 58 static __poll_t coda_psdev_poll(struct file *file, poll_table * wait)
 59 {
 60         struct venus_comm *vcp = (struct venus_comm *) file->private_data;
 61         __poll_t mask = EPOLLOUT | EPOLLWRNORM;
 62 
 63         poll_wait(file, &vcp->vc_waitq, wait);
 64         mutex_lock(&vcp->vc_mutex);
 65         if (!list_empty(&vcp->vc_pending))
 66                 mask |= EPOLLIN | EPOLLRDNORM;
 67         mutex_unlock(&vcp->vc_mutex);
 68 
 69         return mask;
 70 }
 71 
 72 static long coda_psdev_ioctl(struct file * filp, unsigned int cmd, unsigned long arg)
 73 {
 74         unsigned int data;
 75 
 76         switch(cmd) {
 77         case CIOC_KERNEL_VERSION:
 78                 data = CODA_KERNEL_VERSION;
 79                 return put_user(data, (int __user *) arg);
 80         default:
 81                 return -ENOTTY;
 82         }
 83 
 84         return 0;
 85 }
 86 
 87 /*
 88  *      Receive a message written by Venus to the psdev
 89  */
 90  
 91 static ssize_t coda_psdev_write(struct file *file, const char __user *buf, 
 92                                 size_t nbytes, loff_t *off)
 93 {
 94         struct venus_comm *vcp = (struct venus_comm *) file->private_data;
 95         struct upc_req *req = NULL;
 96         struct upc_req *tmp;
 97         struct list_head *lh;
 98         struct coda_in_hdr hdr;
 99         ssize_t retval = 0, count = 0;
100         int error;
101 
102         /* make sure there is enough to copy out the (opcode, unique) values */
103         if (nbytes < (2 * sizeof(u_int32_t)))
104                 return -EINVAL;
105 
106         /* Peek at the opcode, uniquefier */
107         if (copy_from_user(&hdr, buf, 2 * sizeof(u_int32_t)))
108                 return -EFAULT;
109 
110         if (DOWNCALL(hdr.opcode)) {
111                 union outputArgs *dcbuf;
112                 int size = sizeof(*dcbuf);
113 
114                 if  ( nbytes < sizeof(struct coda_out_hdr) ) {
115                         pr_warn("coda_downcall opc %d uniq %d, not enough!\n",
116                                 hdr.opcode, hdr.unique);
117                         count = nbytes;
118                         goto out;
119                 }
120                 if ( nbytes > size ) {
121                         pr_warn("downcall opc %d, uniq %d, too much!",
122                                 hdr.opcode, hdr.unique);
123                         nbytes = size;
124                 }
125                 dcbuf = kvmalloc(nbytes, GFP_KERNEL);
126                 if (!dcbuf) {
127                         retval = -ENOMEM;
128                         goto out;
129                 }
130                 if (copy_from_user(dcbuf, buf, nbytes)) {
131                         kvfree(dcbuf);
132                         retval = -EFAULT;
133                         goto out;
134                 }
135 
136                 /* what downcall errors does Venus handle ? */
137                 error = coda_downcall(vcp, hdr.opcode, dcbuf, nbytes);
138 
139                 kvfree(dcbuf);
140                 if (error) {
141                         pr_warn("%s: coda_downcall error: %d\n",
142                                 __func__, error);
143                         retval = error;
144                         goto out;
145                 }
146                 count = nbytes;
147                 goto out;
148         }
149         
150         /* Look for the message on the processing queue. */
151         mutex_lock(&vcp->vc_mutex);
152         list_for_each(lh, &vcp->vc_processing) {
153                 tmp = list_entry(lh, struct upc_req , uc_chain);
154                 if (tmp->uc_unique == hdr.unique) {
155                         req = tmp;
156                         list_del(&req->uc_chain);
157                         break;
158                 }
159         }
160         mutex_unlock(&vcp->vc_mutex);
161 
162         if (!req) {
163                 pr_warn("%s: msg (%d, %d) not found\n",
164                         __func__, hdr.opcode, hdr.unique);
165                 retval = -ESRCH;
166                 goto out;
167         }
168 
169         /* move data into response buffer. */
170         if (req->uc_outSize < nbytes) {
171                 pr_warn("%s: too much cnt: %d, cnt: %ld, opc: %d, uniq: %d.\n",
172                         __func__, req->uc_outSize, (long)nbytes,
173                         hdr.opcode, hdr.unique);
174                 nbytes = req->uc_outSize; /* don't have more space! */
175         }
176         if (copy_from_user(req->uc_data, buf, nbytes)) {
177                 req->uc_flags |= CODA_REQ_ABORT;
178                 wake_up(&req->uc_sleep);
179                 retval = -EFAULT;
180                 goto out;
181         }
182 
183         /* adjust outsize. is this useful ?? */
184         req->uc_outSize = nbytes;
185         req->uc_flags |= CODA_REQ_WRITE;
186         count = nbytes;
187 
188         /* Convert filedescriptor into a file handle */
189         if (req->uc_opcode == CODA_OPEN_BY_FD) {
190                 struct coda_open_by_fd_out *outp =
191                         (struct coda_open_by_fd_out *)req->uc_data;
192                 if (!outp->oh.result) {
193                         outp->fh = fget(outp->fd);
194                         if (!outp->fh)
195                                 return -EBADF;
196                 }
197         }
198 
199         wake_up(&req->uc_sleep);
200 out:
201         return(count ? count : retval);  
202 }
203 
204 /*
205  *      Read a message from the kernel to Venus
206  */
207 
208 static ssize_t coda_psdev_read(struct file * file, char __user * buf, 
209                                size_t nbytes, loff_t *off)
210 {
211         DECLARE_WAITQUEUE(wait, current);
212         struct venus_comm *vcp = (struct venus_comm *) file->private_data;
213         struct upc_req *req;
214         ssize_t retval = 0, count = 0;
215 
216         if (nbytes == 0)
217                 return 0;
218 
219         mutex_lock(&vcp->vc_mutex);
220 
221         add_wait_queue(&vcp->vc_waitq, &wait);
222         set_current_state(TASK_INTERRUPTIBLE);
223 
224         while (list_empty(&vcp->vc_pending)) {
225                 if (file->f_flags & O_NONBLOCK) {
226                         retval = -EAGAIN;
227                         break;
228                 }
229                 if (signal_pending(current)) {
230                         retval = -ERESTARTSYS;
231                         break;
232                 }
233                 mutex_unlock(&vcp->vc_mutex);
234                 schedule();
235                 mutex_lock(&vcp->vc_mutex);
236         }
237 
238         set_current_state(TASK_RUNNING);
239         remove_wait_queue(&vcp->vc_waitq, &wait);
240 
241         if (retval)
242                 goto out;
243 
244         req = list_entry(vcp->vc_pending.next, struct upc_req,uc_chain);
245         list_del(&req->uc_chain);
246 
247         /* Move the input args into userspace */
248         count = req->uc_inSize;
249         if (nbytes < req->uc_inSize) {
250                 pr_warn("%s: Venus read %ld bytes of %d in message\n",
251                         __func__, (long)nbytes, req->uc_inSize);
252                 count = nbytes;
253         }
254 
255         if (copy_to_user(buf, req->uc_data, count))
256                 retval = -EFAULT;
257         
258         /* If request was not a signal, enqueue and don't free */
259         if (!(req->uc_flags & CODA_REQ_ASYNC)) {
260                 req->uc_flags |= CODA_REQ_READ;
261                 list_add_tail(&(req->uc_chain), &vcp->vc_processing);
262                 goto out;
263         }
264 
265         kvfree(req->uc_data);
266         kfree(req);
267 out:
268         mutex_unlock(&vcp->vc_mutex);
269         return (count ? count : retval);
270 }
271 
272 static int coda_psdev_open(struct inode * inode, struct file * file)
273 {
274         struct venus_comm *vcp;
275         int idx, err;
276 
277         if (task_active_pid_ns(current) != &init_pid_ns)
278                 return -EINVAL;
279 
280         if (current_user_ns() != &init_user_ns)
281                 return -EINVAL;
282 
283         idx = iminor(inode);
284         if (idx < 0 || idx >= MAX_CODADEVS)
285                 return -ENODEV;
286 
287         err = -EBUSY;
288         vcp = &coda_comms[idx];
289         mutex_lock(&vcp->vc_mutex);
290 
291         if (!vcp->vc_inuse) {
292                 vcp->vc_inuse++;
293 
294                 INIT_LIST_HEAD(&vcp->vc_pending);
295                 INIT_LIST_HEAD(&vcp->vc_processing);
296                 init_waitqueue_head(&vcp->vc_waitq);
297                 vcp->vc_sb = NULL;
298                 vcp->vc_seq = 0;
299 
300                 file->private_data = vcp;
301                 err = 0;
302         }
303 
304         mutex_unlock(&vcp->vc_mutex);
305         return err;
306 }
307 
308 
309 static int coda_psdev_release(struct inode * inode, struct file * file)
310 {
311         struct venus_comm *vcp = (struct venus_comm *) file->private_data;
312         struct upc_req *req, *tmp;
313 
314         if (!vcp || !vcp->vc_inuse ) {
315                 pr_warn("%s: Not open.\n", __func__);
316                 return -1;
317         }
318 
319         mutex_lock(&vcp->vc_mutex);
320 
321         /* Wakeup clients so they can return. */
322         list_for_each_entry_safe(req, tmp, &vcp->vc_pending, uc_chain) {
323                 list_del(&req->uc_chain);
324 
325                 /* Async requests need to be freed here */
326                 if (req->uc_flags & CODA_REQ_ASYNC) {
327                         kvfree(req->uc_data);
328                         kfree(req);
329                         continue;
330                 }
331                 req->uc_flags |= CODA_REQ_ABORT;
332                 wake_up(&req->uc_sleep);
333         }
334 
335         list_for_each_entry_safe(req, tmp, &vcp->vc_processing, uc_chain) {
336                 list_del(&req->uc_chain);
337 
338                 req->uc_flags |= CODA_REQ_ABORT;
339                 wake_up(&req->uc_sleep);
340         }
341 
342         file->private_data = NULL;
343         vcp->vc_inuse--;
344         mutex_unlock(&vcp->vc_mutex);
345         return 0;
346 }
347 
348 
349 static const struct file_operations coda_psdev_fops = {
350         .owner          = THIS_MODULE,
351         .read           = coda_psdev_read,
352         .write          = coda_psdev_write,
353         .poll           = coda_psdev_poll,
354         .unlocked_ioctl = coda_psdev_ioctl,
355         .open           = coda_psdev_open,
356         .release        = coda_psdev_release,
357         .llseek         = noop_llseek,
358 };
359 
360 static int __init init_coda_psdev(void)
361 {
362         int i, err = 0;
363         if (register_chrdev(CODA_PSDEV_MAJOR, "coda", &coda_psdev_fops)) {
364                 pr_err("%s: unable to get major %d\n",
365                        __func__, CODA_PSDEV_MAJOR);
366                 return -EIO;
367         }
368         coda_psdev_class = class_create(THIS_MODULE, "coda");
369         if (IS_ERR(coda_psdev_class)) {
370                 err = PTR_ERR(coda_psdev_class);
371                 goto out_chrdev;
372         }               
373         for (i = 0; i < MAX_CODADEVS; i++) {
374                 mutex_init(&(&coda_comms[i])->vc_mutex);
375                 device_create(coda_psdev_class, NULL,
376                               MKDEV(CODA_PSDEV_MAJOR, i), NULL, "cfs%d", i);
377         }
378         coda_sysctl_init();
379         goto out;
380 
381 out_chrdev:
382         unregister_chrdev(CODA_PSDEV_MAJOR, "coda");
383 out:
384         return err;
385 }
386 
387 MODULE_AUTHOR("Jan Harkes, Peter J. Braam");
388 MODULE_DESCRIPTION("Coda Distributed File System VFS interface");
389 MODULE_ALIAS_CHARDEV_MAJOR(CODA_PSDEV_MAJOR);
390 MODULE_LICENSE("GPL");
391 MODULE_VERSION("7.0");
392 
393 static int __init init_coda(void)
394 {
395         int status;
396         int i;
397 
398         status = coda_init_inodecache();
399         if (status)
400                 goto out2;
401         status = init_coda_psdev();
402         if ( status ) {
403                 pr_warn("Problem (%d) in init_coda_psdev\n", status);
404                 goto out1;
405         }
406         
407         status = register_filesystem(&coda_fs_type);
408         if (status) {
409                 pr_warn("failed to register filesystem!\n");
410                 goto out;
411         }
412         return 0;
413 out:
414         for (i = 0; i < MAX_CODADEVS; i++)
415                 device_destroy(coda_psdev_class, MKDEV(CODA_PSDEV_MAJOR, i));
416         class_destroy(coda_psdev_class);
417         unregister_chrdev(CODA_PSDEV_MAJOR, "coda");
418         coda_sysctl_clean();
419 out1:
420         coda_destroy_inodecache();
421 out2:
422         return status;
423 }
424 
425 static void __exit exit_coda(void)
426 {
427         int err, i;
428 
429         err = unregister_filesystem(&coda_fs_type);
430         if (err != 0)
431                 pr_warn("failed to unregister filesystem\n");
432         for (i = 0; i < MAX_CODADEVS; i++)
433                 device_destroy(coda_psdev_class, MKDEV(CODA_PSDEV_MAJOR, i));
434         class_destroy(coda_psdev_class);
435         unregister_chrdev(CODA_PSDEV_MAJOR, "coda");
436         coda_sysctl_clean();
437         coda_destroy_inodecache();
438 }
439 
440 module_init(init_coda);
441 module_exit(exit_coda);
442 
443 

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