linux/include/asm-generic/checksum.h
Alexander Duyck 01cfbad79a ipv4: Update parameters for csum_tcpudp_magic to their original types
This patch updates all instances of csum_tcpudp_magic and
csum_tcpudp_nofold to reflect the types that are usually used as the source
inputs.  For example the protocol field is populated based on nexthdr which
is actually an unsigned 8 bit value.  The length is usually populated based
on skb->len which is an unsigned integer.

This addresses an issue in which the IPv6 function csum_ipv6_magic was
generating a checksum using the full 32b of skb->len while
csum_tcpudp_magic was only using the lower 16 bits.  As a result we could
run into issues when attempting to adjust the checksum as there was no
protocol agnostic way to update it.

With this change the value is still truncated as many architectures use
"(len + proto) << 8", however this truncation only occurs for values
greater than 16776960 in length and as such is unlikely to occur as we stop
the inner headers at ~64K in size.

I did have to make a few minor changes in the arm, mn10300, nios2, and
score versions of the function in order to support these changes as they
were either using things such as an OR to combine the protocol and length,
or were using ntohs to convert the length which would have truncated the
value.

I also updated a few spots in terms of whitespace and type differences for
the addresses.  Most of this was just to make sure all of the definitions
were in sync going forward.

Signed-off-by: Alexander Duyck <aduyck@mirantis.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-03-13 23:55:13 -04:00

87 lines
2.2 KiB
C

#ifndef __ASM_GENERIC_CHECKSUM_H
#define __ASM_GENERIC_CHECKSUM_H
/*
* computes the checksum of a memory block at buff, length len,
* and adds in "sum" (32-bit)
*
* returns a 32-bit number suitable for feeding into itself
* or csum_tcpudp_magic
*
* this function must be called with even lengths, except
* for the last fragment, which may be odd
*
* it's best to have buff aligned on a 32-bit boundary
*/
extern __wsum csum_partial(const void *buff, int len, __wsum sum);
/*
* the same as csum_partial, but copies from src while it
* checksums
*
* here even more important to align src and dst on a 32-bit (or even
* better 64-bit) boundary
*/
extern __wsum csum_partial_copy(const void *src, void *dst, int len, __wsum sum);
/*
* the same as csum_partial_copy, but copies from user space.
*
* here even more important to align src and dst on a 32-bit (or even
* better 64-bit) boundary
*/
extern __wsum csum_partial_copy_from_user(const void __user *src, void *dst,
int len, __wsum sum, int *csum_err);
#ifndef csum_partial_copy_nocheck
#define csum_partial_copy_nocheck(src, dst, len, sum) \
csum_partial_copy((src), (dst), (len), (sum))
#endif
#ifndef ip_fast_csum
/*
* This is a version of ip_compute_csum() optimized for IP headers,
* which always checksum on 4 octet boundaries.
*/
extern __sum16 ip_fast_csum(const void *iph, unsigned int ihl);
#endif
#ifndef csum_fold
/*
* Fold a partial checksum
*/
static inline __sum16 csum_fold(__wsum csum)
{
u32 sum = (__force u32)csum;
sum = (sum & 0xffff) + (sum >> 16);
sum = (sum & 0xffff) + (sum >> 16);
return (__force __sum16)~sum;
}
#endif
#ifndef csum_tcpudp_nofold
/*
* computes the checksum of the TCP/UDP pseudo-header
* returns a 16-bit checksum, already complemented
*/
extern __wsum
csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len,
__u8 proto, __wsum sum);
#endif
#ifndef csum_tcpudp_magic
static inline __sum16
csum_tcpudp_magic(__be32 saddr, __be32 daddr, __u32 len,
__u8 proto, __wsum sum)
{
return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum));
}
#endif
/*
* this routine is used for miscellaneous IP-like checksums, mainly
* in icmp.c
*/
extern __sum16 ip_compute_csum(const void *buff, int len);
#endif /* __ASM_GENERIC_CHECKSUM_H */