1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/net/sunrpc/socklib.c
4 *
5 * Common socket helper routines for RPC client and server
6 *
7 * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
8 */
9
10#include <linux/compiler.h>
11#include <linux/netdevice.h>
12#include <linux/gfp.h>
13#include <linux/skbuff.h>
14#include <linux/types.h>
15#include <linux/pagemap.h>
16#include <linux/udp.h>
17#include <linux/sunrpc/msg_prot.h>
18#include <linux/sunrpc/sched.h>
19#include <linux/sunrpc/xdr.h>
20#include <linux/export.h>
21
22#include "socklib.h"
23
24/*
25 * Helper structure for copying from an sk_buff.
26 */
27struct xdr_skb_reader {
28	struct sk_buff	*skb;
29	unsigned int	offset;
30	size_t		count;
31	__wsum		csum;
32};
33
34typedef size_t (*xdr_skb_read_actor)(struct xdr_skb_reader *desc, void *to,
35				     size_t len);
36
37/**
38 * xdr_skb_read_bits - copy some data bits from skb to internal buffer
39 * @desc: sk_buff copy helper
40 * @to: copy destination
41 * @len: number of bytes to copy
42 *
43 * Possibly called several times to iterate over an sk_buff and copy
44 * data out of it.
45 */
46static size_t
47xdr_skb_read_bits(struct xdr_skb_reader *desc, void *to, size_t len)
48{
49	if (len > desc->count)
50		len = desc->count;
51	if (unlikely(skb_copy_bits(desc->skb, desc->offset, to, len)))
52		return 0;
53	desc->count -= len;
54	desc->offset += len;
55	return len;
56}
57
58/**
59 * xdr_skb_read_and_csum_bits - copy and checksum from skb to buffer
60 * @desc: sk_buff copy helper
61 * @to: copy destination
62 * @len: number of bytes to copy
63 *
64 * Same as skb_read_bits, but calculate a checksum at the same time.
65 */
66static size_t xdr_skb_read_and_csum_bits(struct xdr_skb_reader *desc, void *to, size_t len)
67{
68	unsigned int pos;
69	__wsum csum2;
70
71	if (len > desc->count)
72		len = desc->count;
73	pos = desc->offset;
74	csum2 = skb_copy_and_csum_bits(desc->skb, pos, to, len);
75	desc->csum = csum_block_add(desc->csum, csum2, pos);
76	desc->count -= len;
77	desc->offset += len;
78	return len;
79}
80
81/**
82 * xdr_partial_copy_from_skb - copy data out of an skb
83 * @xdr: target XDR buffer
84 * @base: starting offset
85 * @desc: sk_buff copy helper
86 * @copy_actor: virtual method for copying data
87 *
88 */
89static ssize_t
90xdr_partial_copy_from_skb(struct xdr_buf *xdr, unsigned int base, struct xdr_skb_reader *desc, xdr_skb_read_actor copy_actor)
91{
92	struct page	**ppage = xdr->pages;
93	unsigned int	len, pglen = xdr->page_len;
94	ssize_t		copied = 0;
95	size_t		ret;
96
97	len = xdr->head[0].iov_len;
98	if (base < len) {
99		len -= base;
100		ret = copy_actor(desc, (char *)xdr->head[0].iov_base + base, len);
101		copied += ret;
102		if (ret != len || !desc->count)
103			goto out;
104		base = 0;
105	} else
106		base -= len;
107
108	if (unlikely(pglen == 0))
109		goto copy_tail;
110	if (unlikely(base >= pglen)) {
111		base -= pglen;
112		goto copy_tail;
113	}
114	if (base || xdr->page_base) {
115		pglen -= base;
116		base += xdr->page_base;
117		ppage += base >> PAGE_SHIFT;
118		base &= ~PAGE_MASK;
119	}
120	do {
121		char *kaddr;
122
123		/* ACL likes to be lazy in allocating pages - ACLs
124		 * are small by default but can get huge. */
125		if ((xdr->flags & XDRBUF_SPARSE_PAGES) && *ppage == NULL) {
126			*ppage = alloc_page(GFP_NOWAIT | __GFP_NOWARN);
127			if (unlikely(*ppage == NULL)) {
128				if (copied == 0)
129					copied = -ENOMEM;
130				goto out;
131			}
132		}
133
134		len = PAGE_SIZE;
135		kaddr = kmap_atomic(*ppage);
136		if (base) {
137			len -= base;
138			if (pglen < len)
139				len = pglen;
140			ret = copy_actor(desc, kaddr + base, len);
141			base = 0;
142		} else {
143			if (pglen < len)
144				len = pglen;
145			ret = copy_actor(desc, kaddr, len);
146		}
147		flush_dcache_page(*ppage);
148		kunmap_atomic(kaddr);
149		copied += ret;
150		if (ret != len || !desc->count)
151			goto out;
152		ppage++;
153	} while ((pglen -= len) != 0);
154copy_tail:
155	len = xdr->tail[0].iov_len;
156	if (base < len)
157		copied += copy_actor(desc, (char *)xdr->tail[0].iov_base + base, len - base);
158out:
159	return copied;
160}
161
162/**
163 * csum_partial_copy_to_xdr - checksum and copy data
164 * @xdr: target XDR buffer
165 * @skb: source skb
166 *
167 * We have set things up such that we perform the checksum of the UDP
168 * packet in parallel with the copies into the RPC client iovec.  -DaveM
169 */
170int csum_partial_copy_to_xdr(struct xdr_buf *xdr, struct sk_buff *skb)
171{
172	struct xdr_skb_reader	desc;
173
174	desc.skb = skb;
175	desc.offset = 0;
176	desc.count = skb->len - desc.offset;
177
178	if (skb_csum_unnecessary(skb))
179		goto no_checksum;
180
181	desc.csum = csum_partial(skb->data, desc.offset, skb->csum);
182	if (xdr_partial_copy_from_skb(xdr, 0, &desc, xdr_skb_read_and_csum_bits) < 0)
183		return -1;
184	if (desc.offset != skb->len) {
185		__wsum csum2;
186		csum2 = skb_checksum(skb, desc.offset, skb->len - desc.offset, 0);
187		desc.csum = csum_block_add(desc.csum, csum2, desc.offset);
188	}
189	if (desc.count)
190		return -1;
191	if (csum_fold(desc.csum))
192		return -1;
193	if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
194	    !skb->csum_complete_sw)
195		netdev_rx_csum_fault(skb->dev, skb);
196	return 0;
197no_checksum:
198	if (xdr_partial_copy_from_skb(xdr, 0, &desc, xdr_skb_read_bits) < 0)
199		return -1;
200	if (desc.count)
201		return -1;
202	return 0;
203}
204EXPORT_SYMBOL_GPL(csum_partial_copy_to_xdr);
205
206static inline int xprt_sendmsg(struct socket *sock, struct msghdr *msg,
207			       size_t seek)
208{
209	if (seek)
210		iov_iter_advance(&msg->msg_iter, seek);
211	return sock_sendmsg(sock, msg);
212}
213
214static int xprt_send_kvec(struct socket *sock, struct msghdr *msg,
215			  struct kvec *vec, size_t seek)
216{
217	iov_iter_kvec(&msg->msg_iter, ITER_SOURCE, vec, 1, vec->iov_len);
218	return xprt_sendmsg(sock, msg, seek);
219}
220
221static int xprt_send_pagedata(struct socket *sock, struct msghdr *msg,
222			      struct xdr_buf *xdr, size_t base)
223{
224	iov_iter_bvec(&msg->msg_iter, ITER_SOURCE, xdr->bvec, xdr_buf_pagecount(xdr),
225		      xdr->page_len + xdr->page_base);
226	return xprt_sendmsg(sock, msg, base + xdr->page_base);
227}
228
229/* Common case:
230 *  - stream transport
231 *  - sending from byte 0 of the message
232 *  - the message is wholly contained in @xdr's head iovec
233 */
234static int xprt_send_rm_and_kvec(struct socket *sock, struct msghdr *msg,
235				 rpc_fraghdr marker, struct kvec *vec,
236				 size_t base)
237{
238	struct kvec iov[2] = {
239		[0] = {
240			.iov_base	= &marker,
241			.iov_len	= sizeof(marker)
242		},
243		[1] = *vec,
244	};
245	size_t len = iov[0].iov_len + iov[1].iov_len;
246
247	iov_iter_kvec(&msg->msg_iter, ITER_SOURCE, iov, 2, len);
248	return xprt_sendmsg(sock, msg, base);
249}
250
251/**
252 * xprt_sock_sendmsg - write an xdr_buf directly to a socket
253 * @sock: open socket to send on
254 * @msg: socket message metadata
255 * @xdr: xdr_buf containing this request
256 * @base: starting position in the buffer
257 * @marker: stream record marker field
258 * @sent_p: return the total number of bytes successfully queued for sending
259 *
260 * Return values:
261 *   On success, returns zero and fills in @sent_p.
262 *   %-ENOTSOCK if  @sock is not a struct socket.
263 */
264int xprt_sock_sendmsg(struct socket *sock, struct msghdr *msg,
265		      struct xdr_buf *xdr, unsigned int base,
266		      rpc_fraghdr marker, unsigned int *sent_p)
267{
268	unsigned int rmsize = marker ? sizeof(marker) : 0;
269	unsigned int remainder = rmsize + xdr->len - base;
270	unsigned int want;
271	int err = 0;
272
273	*sent_p = 0;
274
275	if (unlikely(!sock))
276		return -ENOTSOCK;
277
278	msg->msg_flags |= MSG_MORE;
279	want = xdr->head[0].iov_len + rmsize;
280	if (base < want) {
281		unsigned int len = want - base;
282
283		remainder -= len;
284		if (remainder == 0)
285			msg->msg_flags &= ~MSG_MORE;
286		if (rmsize)
287			err = xprt_send_rm_and_kvec(sock, msg, marker,
288						    &xdr->head[0], base);
289		else
290			err = xprt_send_kvec(sock, msg, &xdr->head[0], base);
291		if (remainder == 0 || err != len)
292			goto out;
293		*sent_p += err;
294		base = 0;
295	} else {
296		base -= want;
297	}
298
299	if (base < xdr->page_len) {
300		unsigned int len = xdr->page_len - base;
301
302		remainder -= len;
303		if (remainder == 0)
304			msg->msg_flags &= ~MSG_MORE;
305		err = xprt_send_pagedata(sock, msg, xdr, base);
306		if (remainder == 0 || err != len)
307			goto out;
308		*sent_p += err;
309		base = 0;
310	} else {
311		base -= xdr->page_len;
312	}
313
314	if (base >= xdr->tail[0].iov_len)
315		return 0;
316	msg->msg_flags &= ~MSG_MORE;
317	err = xprt_send_kvec(sock, msg, &xdr->tail[0], base);
318out:
319	if (err > 0) {
320		*sent_p += err;
321		err = 0;
322	}
323	return err;
324}
325