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