Introduce a helper to copy datagram into an iovec iterator
but also update a predefined hash. This is useful for
consumers of skb_copy_datagram_iter to also support inflight
data digest without having to finish to copy and only then
traverse the iovec and calculate the digest hash.
Signed-off-by: Sagi Grimberg <sagi@xxxxxxxxxxxxxxxxx>
---
include/linux/skbuff.h | 3 ++
net/core/datagram.c | 90 ++++++++++++++++++++++++++++++++++++++++++
2 files changed, 93 insertions(+)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 0ba687454267..4d89bb14c2fc 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -3311,6 +3311,9 @@ int skb_copy_and_csum_datagram_msg(struct sk_buff *skb, int hlen,
struct msghdr *msg);
int skb_copy_datagram_from_iter(struct sk_buff *skb, int offset,
struct iov_iter *from, int len);
+int skb_copy_and_hash_datagram_iter(const struct sk_buff *skb, int offset,
+ struct iov_iter *to, int len,
+ struct ahash_request *hash);
int zerocopy_sg_from_iter(struct sk_buff *skb, struct iov_iter *frm);
void skb_free_datagram(struct sock *sk, struct sk_buff *skb);
void __skb_free_datagram_locked(struct sock *sk, struct sk_buff *skb, int len);
diff --git a/net/core/datagram.c b/net/core/datagram.c
index 57f3a6fcfc1e..9c81741c1bae 100644
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -497,6 +497,96 @@ int skb_copy_datagram_iter(const struct sk_buff *skb, int offset,
}
EXPORT_SYMBOL(skb_copy_datagram_iter);
+/**
+ * skb_copy_and_hash_datagram_iter - Copy datagram to an iovec iterator
+ * and update a hash.
+ * @skb: buffer to copy
+ * @offset: offset in the buffer to start copying from
+ * @to: iovec iterator to copy to
+ * @len: amount of data to copy from buffer to iovec
+ * @hash: hash request to update
+ */
+int skb_copy_and_hash_datagram_iter(const struct sk_buff *skb, int offset,
+ struct iov_iter *to, int len,
+ struct ahash_request *hash)
+{
+ int start = skb_headlen(skb);
+ int i, copy = start - offset, start_off = offset, n;
+ struct sk_buff *frag_iter;
+
+ /* Copy header. */
+ if (copy > 0) {
+ if (copy > len)
+ copy = len;
+ n = hash_and_copy_to_iter(skb->data + offset, copy, to, hash);
+ offset += n;
+ if (n != copy)
+ goto short_copy;
+ if ((len -= copy) == 0)
+ return 0;
+ }
+
+ /* Copy paged appendix. Hmm... why does this look so complicated? */
+ for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+ int end;
+ const skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
+
+ WARN_ON(start > offset + len);
+
+ end = start + skb_frag_size(frag);
+ if ((copy = end - offset) > 0) {
+ if (copy > len)
+ copy = len;
+ n = hash_and_copy_page_to_iter(skb_frag_page(frag),
+ frag->page_offset + offset -
+ start, copy, to, hash);
+ offset += n;
+ if (n != copy)
+ goto short_copy;
+ if (!(len -= copy))
+ return 0;
+ }
+ start = end;
+ }
+
+ skb_walk_frags(skb, frag_iter) {
+ int end;
+
+ WARN_ON(start > offset + len);
+
+ end = start + frag_iter->len;
+ if ((copy = end - offset) > 0) {
+ if (copy > len)
+ copy = len;
+ if (skb_copy_and_hash_datagram_iter(frag_iter,
+ offset - start, to, copy, hash))
+ goto fault;
+ if ((len -= copy) == 0)
+ return 0;
+ offset += copy;
+ }
+ start = end;
+ }
+ if (!len)
+ return 0;
+
+ /* This is not really a user copy fault, but rather someone
+ * gave us a bogus length on the skb. We should probably
+ * print a warning here as it may indicate a kernel bug.
+ */
+
+fault:
+ iov_iter_revert(to, offset - start_off);
+ return -EFAULT;
+
+short_copy:
+ if (iov_iter_count(to))
+ goto fault;
+
+ return 0;
+}
+EXPORT_SYMBOL(skb_copy_and_hash_datagram_iter);
+
/**
* skb_copy_datagram_from_iter - Copy a datagram from an iov_iter.
* @skb: buffer to copy
--
2.17.1
