LXR linux/net/sunrpc/socklib.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * linux/net/sunrpc/socklib.c
   4 *
   5 * Common socket helper routines for RPC client and server
   6 *
   7 * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
   8 */
   9
  10#include <linux/compiler.h>
  11#include <linux/netdevice.h>
  12#include <linux/gfp.h>
  13#include <linux/skbuff.h>
  14#include <linux/types.h>
  15#include <linux/pagemap.h>
  16#include <linux/udp.h>
  17#include <linux/sunrpc/xdr.h>
  18#include <linux/export.h>
  19
  20
  21/**
  22 * xdr_skb_read_bits - copy some data bits from skb to internal buffer
  23 * @desc: sk_buff copy helper
  24 * @to: copy destination
  25 * @len: number of bytes to copy
  26 *
  27 * Possibly called several times to iterate over an sk_buff and copy
  28 * data out of it.
  29 */
  30static size_t
  31xdr_skb_read_bits(struct xdr_skb_reader *desc, void *to, size_t len)
  32{
  33        if (len > desc->count)
  34                len = desc->count;
  35        if (unlikely(skb_copy_bits(desc->skb, desc->offset, to, len)))
  36                return 0;
  37        desc->count -= len;
  38        desc->offset += len;
  39        return len;
  40}
  41
  42/**
  43 * xdr_skb_read_and_csum_bits - copy and checksum from skb to buffer
  44 * @desc: sk_buff copy helper
  45 * @to: copy destination
  46 * @len: number of bytes to copy
  47 *
  48 * Same as skb_read_bits, but calculate a checksum at the same time.
  49 */
  50static size_t xdr_skb_read_and_csum_bits(struct xdr_skb_reader *desc, void *to, size_t len)
  51{
  52        unsigned int pos;
  53        __wsum csum2;
  54
  55        if (len > desc->count)
  56                len = desc->count;
  57        pos = desc->offset;
  58        csum2 = skb_copy_and_csum_bits(desc->skb, pos, to, len, 0);
  59        desc->csum = csum_block_add(desc->csum, csum2, pos);
  60        desc->count -= len;
  61        desc->offset += len;
  62        return len;
  63}
  64
  65/**
  66 * xdr_partial_copy_from_skb - copy data out of an skb
  67 * @xdr: target XDR buffer
  68 * @base: starting offset
  69 * @desc: sk_buff copy helper
  70 * @copy_actor: virtual method for copying data
  71 *
  72 */
  73static ssize_t
  74xdr_partial_copy_from_skb(struct xdr_buf *xdr, unsigned int base, struct xdr_skb_reader *desc, xdr_skb_read_actor copy_actor)
  75{
  76        struct page     **ppage = xdr->pages;
  77        unsigned int    len, pglen = xdr->page_len;
  78        ssize_t         copied = 0;
  79        size_t          ret;
  80
  81        len = xdr->head[0].iov_len;
  82        if (base < len) {
  83                len -= base;
  84                ret = copy_actor(desc, (char *)xdr->head[0].iov_base + base, len);
  85                copied += ret;
  86                if (ret != len || !desc->count)
  87                        goto out;
  88                base = 0;
  89        } else
  90                base -= len;
  91
  92        if (unlikely(pglen == 0))
  93                goto copy_tail;
  94        if (unlikely(base >= pglen)) {
  95                base -= pglen;
  96                goto copy_tail;
  97        }
  98        if (base || xdr->page_base) {
  99                pglen -= base;
 100                base += xdr->page_base;
 101                ppage += base >> PAGE_SHIFT;
 102                base &= ~PAGE_MASK;
 103        }
 104        do {
 105                char *kaddr;
 106
 107                /* ACL likes to be lazy in allocating pages - ACLs
 108                 * are small by default but can get huge. */
 109                if ((xdr->flags & XDRBUF_SPARSE_PAGES) && *ppage == NULL) {
 110                        *ppage = alloc_page(GFP_NOWAIT | __GFP_NOWARN);
 111                        if (unlikely(*ppage == NULL)) {
 112                                if (copied == 0)
 113                                        copied = -ENOMEM;
 114                                goto out;
 115                        }
 116                }
 117
 118                len = PAGE_SIZE;
 119                kaddr = kmap_atomic(*ppage);
 120                if (base) {
 121                        len -= base;
 122                        if (pglen < len)
 123                                len = pglen;
 124                        ret = copy_actor(desc, kaddr + base, len);
 125                        base = 0;
 126                } else {
 127                        if (pglen < len)
 128                                len = pglen;
 129                        ret = copy_actor(desc, kaddr, len);
 130                }
 131                flush_dcache_page(*ppage);
 132                kunmap_atomic(kaddr);
 133                copied += ret;
 134                if (ret != len || !desc->count)
 135                        goto out;
 136                ppage++;
 137        } while ((pglen -= len) != 0);
 138copy_tail:
 139        len = xdr->tail[0].iov_len;
 140        if (base < len)
 141                copied += copy_actor(desc, (char *)xdr->tail[0].iov_base + base, len - base);
 142out:
 143        return copied;
 144}
 145
 146/**
 147 * csum_partial_copy_to_xdr - checksum and copy data
 148 * @xdr: target XDR buffer
 149 * @skb: source skb
 150 *
 151 * We have set things up such that we perform the checksum of the UDP
 152 * packet in parallel with the copies into the RPC client iovec.  -DaveM
 153 */
 154int csum_partial_copy_to_xdr(struct xdr_buf *xdr, struct sk_buff *skb)
 155{
 156        struct xdr_skb_reader   desc;
 157
 158        desc.skb = skb;
 159        desc.offset = 0;
 160        desc.count = skb->len - desc.offset;
 161
 162        if (skb_csum_unnecessary(skb))
 163                goto no_checksum;
 164
 165        desc.csum = csum_partial(skb->data, desc.offset, skb->csum);
 166        if (xdr_partial_copy_from_skb(xdr, 0, &desc, xdr_skb_read_and_csum_bits) < 0)
 167                return -1;
 168        if (desc.offset != skb->len) {
 169                __wsum csum2;
 170                csum2 = skb_checksum(skb, desc.offset, skb->len - desc.offset, 0);
 171                desc.csum = csum_block_add(desc.csum, csum2, desc.offset);
 172        }
 173        if (desc.count)
 174                return -1;
 175        if (csum_fold(desc.csum))
 176                return -1;
 177        if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
 178            !skb->csum_complete_sw)
 179                netdev_rx_csum_fault(skb->dev, skb);
 180        return 0;
 181no_checksum:
 182        if (xdr_partial_copy_from_skb(xdr, 0, &desc, xdr_skb_read_bits) < 0)
 183                return -1;
 184        if (desc.count)
 185                return -1;
 186        return 0;
 187}
 188EXPORT_SYMBOL_GPL(csum_partial_copy_to_xdr);
 189