net/sunrpc/socklib.c

   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, KM_SKB_SUNRPC_DATA);
 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, KM_SKB_SUNRPC_DATA);
 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                 netdev_rx_csum_fault(skb->dev);
 178         return 0;
 179 no_checksum:
 180         if (xdr_partial_copy_from_skb(xdr, 0, &desc, xdr_skb_read_bits) < 0)
 181                 return -1;
 182         if (desc.count)
 183                 return -1;
 184         return 0;
 185 }
 186 EXPORT_SYMBOL_GPL(csum_partial_copy_to_xdr);