1// SPDX-License-Identifier: GPL-2.0-only
  2/* Copyright (c) 2016 Tom Herbert <tom@herbertland.com> */
  3
  4#include <linux/skbuff.h>
  5#include <linux/workqueue.h>
  6#include <net/strparser.h>
  7#include <net/tcp.h>
  8#include <net/sock.h>
  9#include <net/tls.h>
 10
 11#include "tls.h"
 12
 13static struct workqueue_struct *tls_strp_wq;
 14
 15static void tls_strp_abort_strp(struct tls_strparser *strp, int err)
 16{
 17	if (strp->stopped)
 18		return;
 19
 20	strp->stopped = 1;
 21
 22	/* Report an error on the lower socket */
 23	strp->sk->sk_err = -err;
 24	sk_error_report(strp->sk);
 25}
 26
 27static void tls_strp_anchor_free(struct tls_strparser *strp)
 28{
 29	struct skb_shared_info *shinfo = skb_shinfo(strp->anchor);
 30
 31	DEBUG_NET_WARN_ON_ONCE(atomic_read(&shinfo->dataref) != 1);
 32	shinfo->frag_list = NULL;
 33	consume_skb(strp->anchor);
 34	strp->anchor = NULL;
 35}
 36
 37/* Create a new skb with the contents of input copied to its page frags */
 38static struct sk_buff *tls_strp_msg_make_copy(struct tls_strparser *strp)
 39{
 40	struct strp_msg *rxm;
 41	struct sk_buff *skb;
 42	int i, err, offset;
 43
 44	skb = alloc_skb_with_frags(0, strp->stm.full_len, TLS_PAGE_ORDER,
 45				   &err, strp->sk->sk_allocation);
 46	if (!skb)
 47		return NULL;
 48
 49	offset = strp->stm.offset;
 50	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
 51		skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
 52
 53		WARN_ON_ONCE(skb_copy_bits(strp->anchor, offset,
 54					   skb_frag_address(frag),
 55					   skb_frag_size(frag)));
 56		offset += skb_frag_size(frag);
 57	}
 58
 59	skb_copy_header(skb, strp->anchor);
 60	rxm = strp_msg(skb);
 61	rxm->offset = 0;
 62	return skb;
 63}
 64
 65/* Steal the input skb, input msg is invalid after calling this function */
 66struct sk_buff *tls_strp_msg_detach(struct tls_sw_context_rx *ctx)
 67{
 68	struct tls_strparser *strp = &ctx->strp;
 69
 70#ifdef CONFIG_TLS_DEVICE
 71	DEBUG_NET_WARN_ON_ONCE(!strp->anchor->decrypted);
 72#else
 73	/* This function turns an input into an output,
 74	 * that can only happen if we have offload.
 75	 */
 76	WARN_ON(1);
 77#endif
 78
 79	if (strp->copy_mode) {
 80		struct sk_buff *skb;
 81
 82		/* Replace anchor with an empty skb, this is a little
 83		 * dangerous but __tls_cur_msg() warns on empty skbs
 84		 * so hopefully we'll catch abuses.
 85		 */
 86		skb = alloc_skb(0, strp->sk->sk_allocation);
 87		if (!skb)
 88			return NULL;
 89
 90		swap(strp->anchor, skb);
 91		return skb;
 92	}
 93
 94	return tls_strp_msg_make_copy(strp);
 95}
 96
 97/* Force the input skb to be in copy mode. The data ownership remains
 98 * with the input skb itself (meaning unpause will wipe it) but it can
 99 * be modified.
100 */
101int tls_strp_msg_cow(struct tls_sw_context_rx *ctx)
102{
103	struct tls_strparser *strp = &ctx->strp;
104	struct sk_buff *skb;
105
106	if (strp->copy_mode)
107		return 0;
108
109	skb = tls_strp_msg_make_copy(strp);
110	if (!skb)
111		return -ENOMEM;
112
113	tls_strp_anchor_free(strp);
114	strp->anchor = skb;
115
116	tcp_read_done(strp->sk, strp->stm.full_len);
117	strp->copy_mode = 1;
118
119	return 0;
120}
121
122/* Make a clone (in the skb sense) of the input msg to keep a reference
123 * to the underlying data. The reference-holding skbs get placed on
124 * @dst.
125 */
126int tls_strp_msg_hold(struct tls_strparser *strp, struct sk_buff_head *dst)
127{
128	struct skb_shared_info *shinfo = skb_shinfo(strp->anchor);
129
130	if (strp->copy_mode) {
131		struct sk_buff *skb;
132
133		WARN_ON_ONCE(!shinfo->nr_frags);
134
135		/* We can't skb_clone() the anchor, it gets wiped by unpause */
136		skb = alloc_skb(0, strp->sk->sk_allocation);
137		if (!skb)
138			return -ENOMEM;
139
140		__skb_queue_tail(dst, strp->anchor);
141		strp->anchor = skb;
142	} else {
143		struct sk_buff *iter, *clone;
144		int chunk, len, offset;
145
146		offset = strp->stm.offset;
147		len = strp->stm.full_len;
148		iter = shinfo->frag_list;
149
150		while (len > 0) {
151			if (iter->len <= offset) {
152				offset -= iter->len;
153				goto next;
154			}
155
156			chunk = iter->len - offset;
157			offset = 0;
158
159			clone = skb_clone(iter, strp->sk->sk_allocation);
160			if (!clone)
161				return -ENOMEM;
162			__skb_queue_tail(dst, clone);
163
164			len -= chunk;
165next:
166			iter = iter->next;
167		}
168	}
169
170	return 0;
171}
172
173static void tls_strp_flush_anchor_copy(struct tls_strparser *strp)
174{
175	struct skb_shared_info *shinfo = skb_shinfo(strp->anchor);
176	int i;
177
178	DEBUG_NET_WARN_ON_ONCE(atomic_read(&shinfo->dataref) != 1);
179
180	for (i = 0; i < shinfo->nr_frags; i++)
181		__skb_frag_unref(&shinfo->frags[i], false);
182	shinfo->nr_frags = 0;
183	strp->copy_mode = 0;
184}
185
186static int tls_strp_copyin(read_descriptor_t *desc, struct sk_buff *in_skb,
187			   unsigned int offset, size_t in_len)
188{
189	struct tls_strparser *strp = (struct tls_strparser *)desc->arg.data;
190	struct sk_buff *skb;
191	skb_frag_t *frag;
192	size_t len, chunk;
193	int sz;
194
195	if (strp->msg_ready)
196		return 0;
197
198	skb = strp->anchor;
199	frag = &skb_shinfo(skb)->frags[skb->len / PAGE_SIZE];
200
201	len = in_len;
202	/* First make sure we got the header */
203	if (!strp->stm.full_len) {
204		/* Assume one page is more than enough for headers */
205		chunk =	min_t(size_t, len, PAGE_SIZE - skb_frag_size(frag));
206		WARN_ON_ONCE(skb_copy_bits(in_skb, offset,
207					   skb_frag_address(frag) +
208					   skb_frag_size(frag),
209					   chunk));
210
211		sz = tls_rx_msg_size(strp, strp->anchor);
212		if (sz < 0) {
213			desc->error = sz;
214			return 0;
215		}
216
217		/* We may have over-read, sz == 0 is guaranteed under-read */
218		if (sz > 0)
219			chunk =	min_t(size_t, chunk, sz - skb->len);
220
221		skb->len += chunk;
222		skb->data_len += chunk;
223		skb_frag_size_add(frag, chunk);
224		frag++;
225		len -= chunk;
226		offset += chunk;
227
228		strp->stm.full_len = sz;
229		if (!strp->stm.full_len)
230			goto read_done;
231	}
232
233	/* Load up more data */
234	while (len && strp->stm.full_len > skb->len) {
235		chunk =	min_t(size_t, len, strp->stm.full_len - skb->len);
236		chunk = min_t(size_t, chunk, PAGE_SIZE - skb_frag_size(frag));
237		WARN_ON_ONCE(skb_copy_bits(in_skb, offset,
238					   skb_frag_address(frag) +
239					   skb_frag_size(frag),
240					   chunk));
241
242		skb->len += chunk;
243		skb->data_len += chunk;
244		skb_frag_size_add(frag, chunk);
245		frag++;
246		len -= chunk;
247		offset += chunk;
248	}
249
250	if (strp->stm.full_len == skb->len) {
251		desc->count = 0;
252
253		strp->msg_ready = 1;
254		tls_rx_msg_ready(strp);
255	}
256
257read_done:
258	return in_len - len;
259}
260
261static int tls_strp_read_copyin(struct tls_strparser *strp)
262{
263	struct socket *sock = strp->sk->sk_socket;
264	read_descriptor_t desc;
265
266	desc.arg.data = strp;
267	desc.error = 0;
268	desc.count = 1; /* give more than one skb per call */
269
270	/* sk should be locked here, so okay to do read_sock */
271	sock->ops->read_sock(strp->sk, &desc, tls_strp_copyin);
272
273	return desc.error;
274}
275
276static int tls_strp_read_copy(struct tls_strparser *strp, bool qshort)
277{
278	struct skb_shared_info *shinfo;
279	struct page *page;
280	int need_spc, len;
281
282	/* If the rbuf is small or rcv window has collapsed to 0 we need
283	 * to read the data out. Otherwise the connection will stall.
284	 * Without pressure threshold of INT_MAX will never be ready.
285	 */
286	if (likely(qshort && !tcp_epollin_ready(strp->sk, INT_MAX)))
287		return 0;
288
289	shinfo = skb_shinfo(strp->anchor);
290	shinfo->frag_list = NULL;
291
292	/* If we don't know the length go max plus page for cipher overhead */
293	need_spc = strp->stm.full_len ?: TLS_MAX_PAYLOAD_SIZE + PAGE_SIZE;
294
295	for (len = need_spc; len > 0; len -= PAGE_SIZE) {
296		page = alloc_page(strp->sk->sk_allocation);
297		if (!page) {
298			tls_strp_flush_anchor_copy(strp);
299			return -ENOMEM;
300		}
301
302		skb_fill_page_desc(strp->anchor, shinfo->nr_frags++,
303				   page, 0, 0);
304	}
305
306	strp->copy_mode = 1;
307	strp->stm.offset = 0;
308
309	strp->anchor->len = 0;
310	strp->anchor->data_len = 0;
311	strp->anchor->truesize = round_up(need_spc, PAGE_SIZE);
312
313	tls_strp_read_copyin(strp);
314
315	return 0;
316}
317
318static bool tls_strp_check_no_dup(struct tls_strparser *strp)
319{
320	unsigned int len = strp->stm.offset + strp->stm.full_len;
321	struct sk_buff *skb;
322	u32 seq;
323
324	skb = skb_shinfo(strp->anchor)->frag_list;
325	seq = TCP_SKB_CB(skb)->seq;
326
327	while (skb->len < len) {
328		seq += skb->len;
329		len -= skb->len;
330		skb = skb->next;
331
332		if (TCP_SKB_CB(skb)->seq != seq)
333			return false;
334	}
335
336	return true;
337}
338
339static void tls_strp_load_anchor_with_queue(struct tls_strparser *strp, int len)
340{
341	struct tcp_sock *tp = tcp_sk(strp->sk);
342	struct sk_buff *first;
343	u32 offset;
344
345	first = tcp_recv_skb(strp->sk, tp->copied_seq, &offset);
346	if (WARN_ON_ONCE(!first))
347		return;
348
349	/* Bestow the state onto the anchor */
350	strp->anchor->len = offset + len;
351	strp->anchor->data_len = offset + len;
352	strp->anchor->truesize = offset + len;
353
354	skb_shinfo(strp->anchor)->frag_list = first;
355
356	skb_copy_header(strp->anchor, first);
357	strp->anchor->destructor = NULL;
358
359	strp->stm.offset = offset;
360}
361
362void tls_strp_msg_load(struct tls_strparser *strp, bool force_refresh)
363{
364	struct strp_msg *rxm;
365	struct tls_msg *tlm;
366
367	DEBUG_NET_WARN_ON_ONCE(!strp->msg_ready);
368	DEBUG_NET_WARN_ON_ONCE(!strp->stm.full_len);
369
370	if (!strp->copy_mode && force_refresh) {
371		if (WARN_ON(tcp_inq(strp->sk) < strp->stm.full_len))
372			return;
373
374		tls_strp_load_anchor_with_queue(strp, strp->stm.full_len);
375	}
376
377	rxm = strp_msg(strp->anchor);
378	rxm->full_len	= strp->stm.full_len;
379	rxm->offset	= strp->stm.offset;
380	tlm = tls_msg(strp->anchor);
381	tlm->control	= strp->mark;
382}
383
384/* Called with lock held on lower socket */
385static int tls_strp_read_sock(struct tls_strparser *strp)
386{
387	int sz, inq;
388
389	inq = tcp_inq(strp->sk);
390	if (inq < 1)
391		return 0;
392
393	if (unlikely(strp->copy_mode))
394		return tls_strp_read_copyin(strp);
395
396	if (inq < strp->stm.full_len)
397		return tls_strp_read_copy(strp, true);
398
399	if (!strp->stm.full_len) {
400		tls_strp_load_anchor_with_queue(strp, inq);
401
402		sz = tls_rx_msg_size(strp, strp->anchor);
403		if (sz < 0) {
404			tls_strp_abort_strp(strp, sz);
405			return sz;
406		}
407
408		strp->stm.full_len = sz;
409
410		if (!strp->stm.full_len || inq < strp->stm.full_len)
411			return tls_strp_read_copy(strp, true);
412	}
413
414	if (!tls_strp_check_no_dup(strp))
415		return tls_strp_read_copy(strp, false);
416
417	strp->msg_ready = 1;
418	tls_rx_msg_ready(strp);
419
420	return 0;
421}
422
423void tls_strp_check_rcv(struct tls_strparser *strp)
424{
425	if (unlikely(strp->stopped) || strp->msg_ready)
426		return;
427
428	if (tls_strp_read_sock(strp) == -ENOMEM)
429		queue_work(tls_strp_wq, &strp->work);
430}
431
432/* Lower sock lock held */
433void tls_strp_data_ready(struct tls_strparser *strp)
434{
435	/* This check is needed to synchronize with do_tls_strp_work.
436	 * do_tls_strp_work acquires a process lock (lock_sock) whereas
437	 * the lock held here is bh_lock_sock. The two locks can be
438	 * held by different threads at the same time, but bh_lock_sock
439	 * allows a thread in BH context to safely check if the process
440	 * lock is held. In this case, if the lock is held, queue work.
441	 */
442	if (sock_owned_by_user_nocheck(strp->sk)) {
443		queue_work(tls_strp_wq, &strp->work);
444		return;
445	}
446
447	tls_strp_check_rcv(strp);
448}
449
450static void tls_strp_work(struct work_struct *w)
451{
452	struct tls_strparser *strp =
453		container_of(w, struct tls_strparser, work);
454
455	lock_sock(strp->sk);
456	tls_strp_check_rcv(strp);
457	release_sock(strp->sk);
458}
459
460void tls_strp_msg_done(struct tls_strparser *strp)
461{
462	WARN_ON(!strp->stm.full_len);
463
464	if (likely(!strp->copy_mode))
465		tcp_read_done(strp->sk, strp->stm.full_len);
466	else
467		tls_strp_flush_anchor_copy(strp);
468
469	strp->msg_ready = 0;
470	memset(&strp->stm, 0, sizeof(strp->stm));
471
472	tls_strp_check_rcv(strp);
473}
474
475void tls_strp_stop(struct tls_strparser *strp)
476{
477	strp->stopped = 1;
478}
479
480int tls_strp_init(struct tls_strparser *strp, struct sock *sk)
481{
482	memset(strp, 0, sizeof(*strp));
483
484	strp->sk = sk;
485
486	strp->anchor = alloc_skb(0, GFP_KERNEL);
487	if (!strp->anchor)
488		return -ENOMEM;
489
490	INIT_WORK(&strp->work, tls_strp_work);
491
492	return 0;
493}
494
495/* strp must already be stopped so that tls_strp_recv will no longer be called.
496 * Note that tls_strp_done is not called with the lower socket held.
497 */
498void tls_strp_done(struct tls_strparser *strp)
499{
500	WARN_ON(!strp->stopped);
501
502	cancel_work_sync(&strp->work);
503	tls_strp_anchor_free(strp);
504}
505
506int __init tls_strp_dev_init(void)
507{
508	tls_strp_wq = create_workqueue("tls-strp");
509	if (unlikely(!tls_strp_wq))
510		return -ENOMEM;
511
512	return 0;
513}
514
515void tls_strp_dev_exit(void)
516{
517	destroy_workqueue(tls_strp_wq);
518}