1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* net/atm/pppoatm.c - RFC2364 PPP over ATM/AAL5 */
4 /* Copyright 1999-2000 by Mitchell Blank Jr */
5 /* Based on clip.c; 1995-1999 by Werner Almesberger, EPFL LRC/ICA */
17  * section 8 of RFC2364 - we are supposed to detect a change
19  * to avoid a black-hole being created if our peer loses state
24  *   1.	LLC-encapsulation was missing when it was enabled.  In
27  *   2.	LLC-encapsulation was present when it was disabled.  Then
44 #include <linux/ppp-ioctl.h>
66 	int flags;			/* SC_COMP_PROT - compress protocol */
75  * inflight == -2 represents an empty queue, -1 one packet, and zero means
78 #define NONE_INFLIGHT -2
91 	return (struct pppoatm_vcc *) (atmvcc->user_back);  in atmvcc_to_pvcc()
96 	return (struct pppoatm_vcc *) (chan->private);  in chan_to_pvcc()
108 	ppp_output_wakeup(&pvcc->chan);  in pppoatm_wakeup_sender()
117 	 * the wakeup *can't* race with pppoatm_send(). They both hold the PPP  in pppoatm_release_cb()
118 	 * channel's ->downl lock. And the potential race with *setting* it,  in pppoatm_release_cb()
119 	 * which leads to the double-check dance in pppoatm_may_send(), doesn't  in pppoatm_release_cb()
122 	 * ->release_cb() can't be called until that's done.  in pppoatm_release_cb()
124 	if (test_and_clear_bit(BLOCKED, &pvcc->blocked))  in pppoatm_release_cb()
125 		tasklet_schedule(&pvcc->wakeup_tasklet);  in pppoatm_release_cb()
126 	if (pvcc->old_release_cb)  in pppoatm_release_cb()
127 		pvcc->old_release_cb(atmvcc);  in pppoatm_release_cb()
131  * skb.  The ->old_pop will take care up normal atm flow control,
138 	pvcc->old_pop(atmvcc, skb);  in pppoatm_pop()
139 	atomic_dec(&pvcc->inflight);  in pppoatm_pop()
142 	 * We always used to run the wakeup tasklet unconditionally here, for  in pppoatm_pop()
147 	 * while holding the channel->downl lock. And ppp_output_wakeup() as  in pppoatm_pop()
150 	 * with it. The wakeup *will* happen after the other CPU is safely out  in pppoatm_pop()
154 	 * it about to return, that's fine. We trigger a wakeup which will  in pppoatm_pop()
159 	if (test_and_clear_bit(BLOCKED, &pvcc->blocked))  in pppoatm_pop()
160 		tasklet_schedule(&pvcc->wakeup_tasklet);  in pppoatm_pop()
164  * Unbind from PPP - currently we only do this when closing the socket,
171 	atmvcc->push = pvcc->old_push;  in pppoatm_unassign_vcc()
172 	atmvcc->pop = pvcc->old_pop;  in pppoatm_unassign_vcc()
173 	atmvcc->release_cb = pvcc->old_release_cb;  in pppoatm_unassign_vcc()
174 	tasklet_kill(&pvcc->wakeup_tasklet);  in pppoatm_unassign_vcc()
175 	ppp_unregister_channel(&pvcc->chan);  in pppoatm_unassign_vcc()
176 	atmvcc->user_back = NULL;  in pppoatm_unassign_vcc()
189 		module = pvcc->old_owner;  in pppoatm_push()
191 		atmvcc->push(atmvcc, NULL);	/* Pass along bad news */  in pppoatm_push()
195 	atm_return(atmvcc, skb->truesize);  in pppoatm_push()
196 	switch (pvcc->encaps) {  in pppoatm_push()
198 		if (skb->len < LLC_LEN ||  in pppoatm_push()
199 		    memcmp(skb->data, pppllc, LLC_LEN))  in pppoatm_push()
204 		if (pvcc->chan.ppp == NULL) {	/* Not bound yet! */  in pppoatm_push()
208 		if (skb->len >= sizeof(pppllc) &&  in pppoatm_push()
209 		    !memcmp(skb->data, pppllc, sizeof(pppllc))) {  in pppoatm_push()
210 			pvcc->encaps = e_llc;  in pppoatm_push()
214 		if (skb->len >= (sizeof(pppllc) - LLC_LEN) &&  in pppoatm_push()
215 		    !memcmp(skb->data, &pppllc[LLC_LEN],  in pppoatm_push()
216 		    sizeof(pppllc) - LLC_LEN)) {  in pppoatm_push()
217 			pvcc->encaps = e_vc;  in pppoatm_push()
218 			pvcc->chan.mtu += LLC_LEN;  in pppoatm_push()
221 		pr_debug("Couldn't autodetect yet (skb: %6ph)\n", skb->data);  in pppoatm_push()
226 	ppp_input(&pvcc->chan, skb);  in pppoatm_push()
231 	ppp_input_error(&pvcc->chan, 0);  in pppoatm_push()
238 	 * to check we don't exceed sk->sk_sndbuf. If userspace sets a  in pppoatm_may_send()
243 	if (atm_may_send(pvcc->atmvcc, size) &&  in pppoatm_may_send()
244 	    atomic_inc_not_zero(&pvcc->inflight))  in pppoatm_may_send()
250 	 * *must* be set before we do the atomic_inc() on pvcc->inflight.  in pppoatm_may_send()
254 	test_and_set_bit(BLOCKED, &pvcc->blocked);  in pppoatm_may_send()
264 	 * run the wakeup tasklet. Another wakeup will never hurt.  in pppoatm_may_send()
268 	 * an "immediate" wakeup... where "immediate" actually involves  in pppoatm_may_send()
269 	 * taking the PPP channel's ->downl lock, which is held by the  in pppoatm_may_send()
273 	if (atm_may_send(pvcc->atmvcc, size) &&  in pppoatm_may_send()
274 	    atomic_inc_not_zero(&pvcc->inflight))  in pppoatm_may_send()
280  * Called by the ppp_generic.c to send a packet - returns true if packet
295 	ATM_SKB(skb)->vcc = pvcc->atmvcc;  in pppoatm_send()
296 	pr_debug("(skb=0x%p, vcc=0x%p)\n", skb, pvcc->atmvcc);  in pppoatm_send()
297 	if (skb->data[0] == '\0' && (pvcc->flags & SC_COMP_PROT))  in pppoatm_send()
300 	vcc = ATM_SKB(skb)->vcc;  in pppoatm_send()
305 		 * the socket. It needs to be seen by the time our ->release_cb gets  in pppoatm_send()
308 		test_and_set_bit(BLOCKED, &pvcc->blocked);  in pppoatm_send()
311 	if (test_bit(ATM_VF_RELEASED, &vcc->flags) ||  in pppoatm_send()
312 	    test_bit(ATM_VF_CLOSE, &vcc->flags) ||  in pppoatm_send()
313 	    !test_bit(ATM_VF_READY, &vcc->flags)) {  in pppoatm_send()
319 	switch (pvcc->encaps) {		/* LLC encapsulation needed */  in pppoatm_send()
325 			    !pppoatm_may_send(pvcc, n->truesize)) {  in pppoatm_send()
335 		} else if (!pppoatm_may_send(pvcc, skb->truesize))  in pppoatm_send()
340 		if (!pppoatm_may_send(pvcc, skb->truesize))  in pppoatm_send()
351 	pr_debug("atm_skb(%p)->vcc(%p)->dev(%p)\n",  in pppoatm_send()
352 		 skb, ATM_SKB(skb)->vcc, ATM_SKB(skb)->vcc->dev);  in pppoatm_send()
353 	ret = ATM_SKB(skb)->vcc->send(ATM_SKB(skb)->vcc, skb)  in pppoatm_send()
363 	if ((pvcc->flags & SC_COMP_PROT) && skb_headroom(skb) > 0 &&  in pppoatm_send()
364 	    skb->data[-1] == '\0')  in pppoatm_send()
375 		return put_user(chan_to_pvcc(chan)->flags, (int __user *) arg)  in pppoatm_devppp_ioctl()
376 		    ? -EFAULT : 0;  in pppoatm_devppp_ioctl()
378 		return get_user(chan_to_pvcc(chan)->flags, (int __user *) arg)  in pppoatm_devppp_ioctl()
379 		    ? -EFAULT : 0;  in pppoatm_devppp_ioctl()
381 	return -ENOTTY;  in pppoatm_devppp_ioctl()
396 		return -EFAULT;  in pppoatm_assign_vcc()
399 		return -EINVAL;  in pppoatm_assign_vcc()
402 		return -ENOMEM;  in pppoatm_assign_vcc()
403 	pvcc->atmvcc = atmvcc;  in pppoatm_assign_vcc()
406 	atomic_set(&pvcc->inflight, NONE_INFLIGHT);  in pppoatm_assign_vcc()
407 	pvcc->old_push = atmvcc->push;  in pppoatm_assign_vcc()
408 	pvcc->old_pop = atmvcc->pop;  in pppoatm_assign_vcc()
409 	pvcc->old_owner = atmvcc->owner;  in pppoatm_assign_vcc()
410 	pvcc->old_release_cb = atmvcc->release_cb;  in pppoatm_assign_vcc()
411 	pvcc->encaps = (enum pppoatm_encaps) be.encaps;  in pppoatm_assign_vcc()
412 	pvcc->chan.private = pvcc;  in pppoatm_assign_vcc()
413 	pvcc->chan.ops = &pppoatm_ops;  in pppoatm_assign_vcc()
414 	pvcc->chan.mtu = atmvcc->qos.txtp.max_sdu - PPP_HDRLEN -  in pppoatm_assign_vcc()
416 	tasklet_setup(&pvcc->wakeup_tasklet, pppoatm_wakeup_sender);  in pppoatm_assign_vcc()
417 	err = ppp_register_channel(&pvcc->chan);  in pppoatm_assign_vcc()
422 	atmvcc->user_back = pvcc;  in pppoatm_assign_vcc()
423 	atmvcc->push = pppoatm_push;  in pppoatm_assign_vcc()
424 	atmvcc->pop = pppoatm_pop;  in pppoatm_assign_vcc()
425 	atmvcc->release_cb = pppoatm_release_cb;  in pppoatm_assign_vcc()
427 	atmvcc->owner = THIS_MODULE;  in pppoatm_assign_vcc()
429 	/* re-process everything received between connection setup and  in pppoatm_assign_vcc()
436  * This handles ioctls actually performed on our vcc - we must return
437  * -ENOIOCTLCMD for any unrecognized ioctl
445 	if (cmd != ATM_SETBACKEND && atmvcc->push != pppoatm_push)  in pppoatm_ioctl()
446 		return -ENOIOCTLCMD;  in pppoatm_ioctl()
451 			return -EFAULT;  in pppoatm_ioctl()
453 			return -ENOIOCTLCMD;  in pppoatm_ioctl()
454 		if (!capable(CAP_NET_ADMIN))  in pppoatm_ioctl()
455 			return -EPERM;  in pppoatm_ioctl()
456 		if (sock->state != SS_CONNECTED)  in pppoatm_ioctl()
457 			return -EINVAL;  in pppoatm_ioctl()
461 		return put_user(ppp_channel_index(&atmvcc_to_pvcc(atmvcc)->  in pppoatm_ioctl()
462 		    chan), (int __user *) argp) ? -EFAULT : 0;  in pppoatm_ioctl()
464 		return put_user(ppp_unit_number(&atmvcc_to_pvcc(atmvcc)->  in pppoatm_ioctl()
465 		    chan), (int __user *) argp) ? -EFAULT : 0;  in pppoatm_ioctl()
467 	return -ENOIOCTLCMD;  in pppoatm_ioctl()