Commit 52cbd23a authored by Willem de Bruijn's avatar Willem de Bruijn Committed by Jakub Kicinski
Browse files

udp: fix skb_copy_and_csum_datagram with odd segment sizes 

When iteratively computing a checksum with csum_block_add, track the
offset "pos" to correctly rotate in csum_block_add when offset is odd.

The open coded implementation of skb_copy_and_csum_datagram did this.
With the switch to __skb_datagram_iter calling csum_and_copy_to_iter,
pos was reinitialized to 0 on each call.

Bring back the pos by passing it along with the csum to the callback.

Changes v1->v2
  - pass csum value, instead of csump pointer (Alexander Duyck)

Link: https://lore.kernel.org/netdev/20210128152353.GB27281@optiplex/


Fixes: 950fcaec ("datagram: consolidate datagram copy to iter helpers")
Reported-by: default avatarOliver Graute <oliver.graute@gmail.com>
Signed-off-by: default avatarWillem de Bruijn <willemb@google.com>
Reviewed-by: default avatarAlexander Duyck <alexanderduyck@fb.com>
Reviewed-by: default avatarEric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20210203192952.1849843-1-willemdebruijn.kernel@gmail.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 1d23a56b

include/linux/uio.h

+7 −1
Original line number Diff line number Diff line
@@ -260,7 +260,13 @@ static inline void iov_iter_reexpand(struct iov_iter *i, size_t count) 
{

	i->count = count;

}

size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *csump, struct iov_iter *i);



struct csum_state {

	__wsum csum;

	size_t off;

};



size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *csstate, struct iov_iter *i);

size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);

bool csum_and_copy_from_iter_full(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);

size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp,

lib/iov_iter.c

+14 −10
Original line number Diff line number Diff line
@@ -592,14 +592,15 @@ static __wsum csum_and_memcpy(void *to, const void *from, size_t len, 
}



static size_t csum_and_copy_to_pipe_iter(const void *addr, size_t bytes,

				__wsum *csum, struct iov_iter *i)

					 struct csum_state *csstate,

					 struct iov_iter *i)

{

	struct pipe_inode_info *pipe = i->pipe;

	unsigned int p_mask = pipe->ring_size - 1;

	__wsum sum = csstate->csum;

	size_t off = csstate->off;

	unsigned int i_head;

	size_t n, r;

	size_t off = 0;

	__wsum sum = *csum;



	if (!sanity(i))

		return 0;
@@ -621,7 +622,8 @@ static size_t csum_and_copy_to_pipe_iter(const void *addr, size_t bytes, 
		i_head++;

	} while (n);

	i->count -= bytes;

	*csum = sum;

	csstate->csum = sum;

	csstate->off = off;

	return bytes;

}
@@ -1522,18 +1524,19 @@ bool csum_and_copy_from_iter_full(void *addr, size_t bytes, __wsum *csum, 
}

EXPORT_SYMBOL(csum_and_copy_from_iter_full);



size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *csump,

size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *_csstate,

			     struct iov_iter *i)

{

	struct csum_state *csstate = _csstate;

	const char *from = addr;

	__wsum *csum = csump;

	__wsum sum, next;

	size_t off = 0;

	size_t off;



	if (unlikely(iov_iter_is_pipe(i)))

		return csum_and_copy_to_pipe_iter(addr, bytes, csum, i);

		return csum_and_copy_to_pipe_iter(addr, bytes, _csstate, i);



	sum = *csum;

	sum = csstate->csum;

	off = csstate->off;

	if (unlikely(iov_iter_is_discard(i))) {

		WARN_ON(1);	/* for now */

		return 0;
@@ -1561,7 +1564,8 @@ size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *csump, 
		off += v.iov_len;

	})

	)

	*csum = sum;

	csstate->csum = sum;

	csstate->off = off;

	return bytes;

}

EXPORT_SYMBOL(csum_and_copy_to_iter);

net/core/datagram.c

+10 −2
Original line number Diff line number Diff line
@@ -721,8 +721,16 @@ static int skb_copy_and_csum_datagram(const struct sk_buff *skb, int offset, 
				      struct iov_iter *to, int len,

				      __wsum *csump)

{

	return __skb_datagram_iter(skb, offset, to, len, true,

			csum_and_copy_to_iter, csump);

	struct csum_state csdata = { .csum = *csump };

	int ret;



	ret = __skb_datagram_iter(skb, offset, to, len, true,

				  csum_and_copy_to_iter, &csdata);

	if (ret)

		return ret;



	*csump = csdata.csum;

	return 0;

}



/**