[RFC PATCH 11/36] cifs: Add new AEAD alloc and setup routines that draw from an iterator

Add new AEAD alloc and setup routines that solely use an iterator to supply
the buffers rather than disassembling an smb_rqst struct.

Signed-off-by: David Howells <[email protected]>
cc: Steve French <[email protected]>
cc: Paulo Alcantara <[email protected]>
cc: Shyam Prasad N <[email protected]>
cc: Tom Talpey <[email protected]>
cc: [email protected]
cc: [email protected]
cc: [email protected]
---
 fs/smb/client/smb2transport.c | 69 +++++++++++++++++++++++++++++++++++
 1 file changed, 69 insertions(+)

diff --git a/fs/smb/client/smb2transport.c b/fs/smb/client/smb2transport.c
index f5b676802ce7..9df3a0b530e2 100644
--- a/fs/smb/client/smb2transport.c
+++ b/fs/smb/client/smb2transport.c
@@ -812,3 +812,72 @@ smb3_crypto_aead_allocate(struct TCP_Server_Info *server)
 
 	return 0;
 }
+
+/*
+ * Allocate the context info needed for the encryption operation, along with a
+ * scatterlist to point to the buffer.
+ */
+static void *smb2_aead_req_alloc_new(struct crypto_aead *tfm, const struct iov_iter *iter,
+				 u8 **iv,
+				 struct aead_request **req, struct sg_table *sgt,
+				 unsigned int *num_sgs, size_t *sensitive_size)
+{
+	unsigned int req_size = sizeof(**req) + crypto_aead_reqsize(tfm);
+	unsigned int iv_size = crypto_aead_ivsize(tfm);
+	unsigned int len;
+	u8 *p;
+
+	*num_sgs = iov_iter_npages(iter, INT_MAX);
+
+	len = iv_size;
+	len += crypto_aead_alignmask(tfm) & ~(crypto_tfm_ctx_alignment() - 1);
+	len = ALIGN(len, crypto_tfm_ctx_alignment());
+	len += req_size;
+	len = ALIGN(len, __alignof__(struct scatterlist));
+	len += array_size(*num_sgs + 2, sizeof(struct scatterlist));
+	*sensitive_size = len;
+
+	p = kvzalloc(len, GFP_NOFS);
+	if (!p)
+		return ERR_PTR(-ENOMEM);
+
+	*iv = (u8 *)PTR_ALIGN(p, crypto_aead_alignmask(tfm) + 1);
+	*req = (struct aead_request *)PTR_ALIGN(*iv + iv_size,
+						crypto_tfm_ctx_alignment());
+	sgt->sgl = (struct scatterlist *)PTR_ALIGN((u8 *)*req + req_size,
+						   __alignof__(struct scatterlist));
+	return p;
+}
+
+/*
+ * Set up for doing a crypto operation, building a scatterlist from the
+ * supplied iterator.
+ */
+static void *smb2_get_aead_req_new(struct crypto_aead *tfm, const struct iov_iter *iter,
+				   const u8 *sig, u8 **iv,
+				   struct aead_request **req, struct scatterlist **sgl,
+				   size_t *sensitive_size)
+{
+	struct sg_table sgtable = {};
+	struct iov_iter tmp = *iter;
+	unsigned int num_sgs;
+	ssize_t rc;
+	void *p;
+
+	p = smb2_aead_req_alloc_new(tfm, iter, iv, req, &sgtable,
+				    &num_sgs, sensitive_size);
+	if (IS_ERR(p))
+		return ERR_CAST(p);
+
+	sg_init_marker(sgtable.sgl, num_sgs + 2);
+
+	rc = extract_iter_to_sg(&tmp, iov_iter_count(iter), &sgtable, num_sgs, 0);
+	sgtable.orig_nents = sgtable.nents + 1;
+	if (rc < 0)
+		return ERR_PTR(rc);
+
+	cifs_sg_set_buf(&sgtable, sig, SMB2_SIGNATURE_SIZE);
+	sg_mark_end(&sgtable.sgl[sgtable.nents - 1]);
+	*sgl = sgtable.sgl;
+	return p;
+}