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TOMOYO Linux Cross Reference
Linux/net/sunrpc/socklib.c

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  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 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  */
 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 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  */
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 

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