1/*
2 * linux/net/sunrpc/socklib.c
3 *
4 * Common socket helper routines for RPC client and server
5 *
6 * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
7 */
8
9#include <linux/compiler.h>
10#include <linux/netdevice.h>
11#include <linux/gfp.h>
12#include <linux/skbuff.h>
13#include <linux/types.h>
14#include <linux/pagemap.h>
15#include <linux/udp.h>
16#include <linux/sunrpc/xdr.h>
17#include <linux/export.h>
18
19
20/**
21 * xdr_skb_read_bits - copy some data bits from skb to internal buffer
22 * @desc: sk_buff copy helper
23 * @to: copy destination
24 * @len: number of bytes to copy
25 *
26 * Possibly called several times to iterate over an sk_buff and copy
27 * data out of it.
28 */
29size_t xdr_skb_read_bits(struct xdr_skb_reader *desc, void *to, size_t len)
30{
31	if (len > desc->count)
32		len = desc->count;
33	if (unlikely(skb_copy_bits(desc->skb, desc->offset, to, len)))
34		return 0;
35	desc->count -= len;
36	desc->offset += len;
37	return len;
38}
39EXPORT_SYMBOL_GPL(xdr_skb_read_bits);
40
41/**
42 * xdr_skb_read_and_csum_bits - copy and checksum from skb to buffer
43 * @desc: sk_buff copy helper
44 * @to: copy destination
45 * @len: number of bytes to copy
46 *
47 * Same as skb_read_bits, but calculate a checksum at the same time.
48 */
49static size_t xdr_skb_read_and_csum_bits(struct xdr_skb_reader *desc, void *to, size_t len)
50{
51	unsigned int pos;
52	__wsum csum2;
53
54	if (len > desc->count)
55		len = desc->count;
56	pos = desc->offset;
57	csum2 = skb_copy_and_csum_bits(desc->skb, pos, to, len, 0);
58	desc->csum = csum_block_add(desc->csum, csum2, pos);
59	desc->count -= len;
60	desc->offset += len;
61	return len;
62}
63
64/**
65 * xdr_partial_copy_from_skb - copy data out of an skb
66 * @xdr: target XDR buffer
67 * @base: starting offset
68 * @desc: sk_buff copy helper
69 * @copy_actor: virtual method for copying data
70 *
71 */
72ssize_t xdr_partial_copy_from_skb(struct xdr_buf *xdr, unsigned int base, struct xdr_skb_reader *desc, xdr_skb_read_actor copy_actor)
73{
74	struct page	**ppage = xdr->pages;
75	unsigned int	len, pglen = xdr->page_len;
76	ssize_t		copied = 0;
77	size_t		ret;
78
79	len = xdr->head[0].iov_len;
80	if (base < len) {
81		len -= base;
82		ret = copy_actor(desc, (char *)xdr->head[0].iov_base + base, len);
83		copied += ret;
84		if (ret != len || !desc->count)
85			goto out;
86		base = 0;
87	} else
88		base -= len;
89
90	if (unlikely(pglen == 0))
91		goto copy_tail;
92	if (unlikely(base >= pglen)) {
93		base -= pglen;
94		goto copy_tail;
95	}
96	if (base || xdr->page_base) {
97		pglen -= base;
98		base += xdr->page_base;
99		ppage += base >> PAGE_CACHE_SHIFT;
100		base &= ~PAGE_CACHE_MASK;
101	}
102	do {
103		char *kaddr;
104
105		/* ACL likes to be lazy in allocating pages - ACLs
106		 * are small by default but can get huge. */
107		if (unlikely(*ppage == NULL)) {
108			*ppage = alloc_page(GFP_ATOMIC);
109			if (unlikely(*ppage == NULL)) {
110				if (copied == 0)
111					copied = -ENOMEM;
112				goto out;
113			}
114		}
115
116		len = PAGE_CACHE_SIZE;
117		kaddr = kmap_atomic(*ppage);
118		if (base) {
119			len -= base;
120			if (pglen < len)
121				len = pglen;
122			ret = copy_actor(desc, kaddr + base, len);
123			base = 0;
124		} else {
125			if (pglen < len)
126				len = pglen;
127			ret = copy_actor(desc, kaddr, len);
128		}
129		flush_dcache_page(*ppage);
130		kunmap_atomic(kaddr);
131		copied += ret;
132		if (ret != len || !desc->count)
133			goto out;
134		ppage++;
135	} while ((pglen -= len) != 0);
136copy_tail:
137	len = xdr->tail[0].iov_len;
138	if (base < len)
139		copied += copy_actor(desc, (char *)xdr->tail[0].iov_base + base, len - base);
140out:
141	return copied;
142}
143EXPORT_SYMBOL_GPL(xdr_partial_copy_from_skb);
144
145/**
146 * csum_partial_copy_to_xdr - checksum and copy data
147 * @xdr: target XDR buffer
148 * @skb: source skb
149 *
150 * We have set things up such that we perform the checksum of the UDP
151 * packet in parallel with the copies into the RPC client iovec.  -DaveM
152 */
153int csum_partial_copy_to_xdr(struct xdr_buf *xdr, struct sk_buff *skb)
154{
155	struct xdr_skb_reader	desc;
156
157	desc.skb = skb;
158	desc.offset = sizeof(struct udphdr);
159	desc.count = skb->len - desc.offset;
160
161	if (skb_csum_unnecessary(skb))
162		goto no_checksum;
163
164	desc.csum = csum_partial(skb->data, desc.offset, skb->csum);
165	if (xdr_partial_copy_from_skb(xdr, 0, &desc, xdr_skb_read_and_csum_bits) < 0)
166		return -1;
167	if (desc.offset != skb->len) {
168		__wsum csum2;
169		csum2 = skb_checksum(skb, desc.offset, skb->len - desc.offset, 0);
170		desc.csum = csum_block_add(desc.csum, csum2, desc.offset);
171	}
172	if (desc.count)
173		return -1;
174	if (csum_fold(desc.csum))
175		return -1;
176	if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
177	    !skb->csum_complete_sw)
178		netdev_rx_csum_fault(skb->dev);
179	return 0;
180no_checksum:
181	if (xdr_partial_copy_from_skb(xdr, 0, &desc, xdr_skb_read_bits) < 0)
182		return -1;
183	if (desc.count)
184		return -1;
185	return 0;
186}
187EXPORT_SYMBOL_GPL(csum_partial_copy_to_xdr);
188