xref: /openbmc/linux/net/sunrpc/socklib.c (revision 151f4e2b)
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  */
29 static size_t
30 xdr_skb_read_bits(struct xdr_skb_reader *desc, void *to, size_t len)
31 {
32 	if (len > desc->count)
33 		len = desc->count;
34 	if (unlikely(skb_copy_bits(desc->skb, desc->offset, to, len)))
35 		return 0;
36 	desc->count -= len;
37 	desc->offset += len;
38 	return len;
39 }
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  */
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  */
72 static ssize_t
73 xdr_partial_copy_from_skb(struct xdr_buf *xdr, unsigned int base, struct xdr_skb_reader *desc, xdr_skb_read_actor copy_actor)
74 {
75 	struct page	**ppage = xdr->pages;
76 	unsigned int	len, pglen = xdr->page_len;
77 	ssize_t		copied = 0;
78 	size_t		ret;
79 
80 	len = xdr->head[0].iov_len;
81 	if (base < len) {
82 		len -= base;
83 		ret = copy_actor(desc, (char *)xdr->head[0].iov_base + base, len);
84 		copied += ret;
85 		if (ret != len || !desc->count)
86 			goto out;
87 		base = 0;
88 	} else
89 		base -= len;
90 
91 	if (unlikely(pglen == 0))
92 		goto copy_tail;
93 	if (unlikely(base >= pglen)) {
94 		base -= pglen;
95 		goto copy_tail;
96 	}
97 	if (base || xdr->page_base) {
98 		pglen -= base;
99 		base += xdr->page_base;
100 		ppage += base >> PAGE_SHIFT;
101 		base &= ~PAGE_MASK;
102 	}
103 	do {
104 		char *kaddr;
105 
106 		/* ACL likes to be lazy in allocating pages - ACLs
107 		 * are small by default but can get huge. */
108 		if ((xdr->flags & XDRBUF_SPARSE_PAGES) && *ppage == NULL) {
109 			*ppage = alloc_page(GFP_NOWAIT | __GFP_NOWARN);
110 			if (unlikely(*ppage == NULL)) {
111 				if (copied == 0)
112 					copied = -ENOMEM;
113 				goto out;
114 			}
115 		}
116 
117 		len = PAGE_SIZE;
118 		kaddr = kmap_atomic(*ppage);
119 		if (base) {
120 			len -= base;
121 			if (pglen < len)
122 				len = pglen;
123 			ret = copy_actor(desc, kaddr + base, len);
124 			base = 0;
125 		} else {
126 			if (pglen < len)
127 				len = pglen;
128 			ret = copy_actor(desc, kaddr, len);
129 		}
130 		flush_dcache_page(*ppage);
131 		kunmap_atomic(kaddr);
132 		copied += ret;
133 		if (ret != len || !desc->count)
134 			goto out;
135 		ppage++;
136 	} while ((pglen -= len) != 0);
137 copy_tail:
138 	len = xdr->tail[0].iov_len;
139 	if (base < len)
140 		copied += copy_actor(desc, (char *)xdr->tail[0].iov_base + base, len - base);
141 out:
142 	return copied;
143 }
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  */
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 = 0;
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, skb);
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