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 */
xdr_skb_read_bits(struct xdr_skb_reader * desc,void * to,size_t len)29 size_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 }
39 EXPORT_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 */
xdr_skb_read_and_csum_bits(struct xdr_skb_reader * desc,void * to,size_t len)49 static 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 */
xdr_partial_copy_from_skb(struct xdr_buf * xdr,unsigned int base,struct xdr_skb_reader * desc,xdr_skb_read_actor copy_actor)72 ssize_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);
136 copy_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);
140 out:
141 return copied;
142 }
143 EXPORT_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 */
csum_partial_copy_to_xdr(struct xdr_buf * xdr,struct sk_buff * skb)153 int 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;
180 no_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 }
187 EXPORT_SYMBOL_GPL(csum_partial_copy_to_xdr);
188