xref: /openbmc/linux/net/sunrpc/socklib.c (revision 25985edc)
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  */
28 size_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 }
38 EXPORT_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  */
48 static 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  */
71 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)
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);
135 copy_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);
139 out:
140 	return copied;
141 }
142 EXPORT_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  */
152 int 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;
178 no_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 }
185 EXPORT_SYMBOL_GPL(csum_partial_copy_to_xdr);
186