Commit 39bc5820 authored by David Howells's avatar David Howells Committed by Steve French
Browse files

cifs: Add a function to Hash the contents of an iterator 



Add a function to push the contents of a BVEC-, KVEC- or XARRAY-type
iterator into a synchronous hash algorithm.

UBUF- and IOBUF-type iterators are not supported on the assumption that
either we're doing buffered I/O, in which case we won't see them, or we're
doing direct I/O, in which case the iterator will have been extracted into
a BVEC-type iterator higher up.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
cc: Steve French <sfrench@samba.org>
cc: Shyam Prasad N <nspmangalore@gmail.com>
cc: Rohith Surabattula <rohiths.msft@gmail.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: linux-cifs@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
cc: linux-crypto@vger.kernel.org

Link: https://lore.kernel.org/r/166697257423.61150.12070648579830206483.stgit@warthog.procyon.org.uk/ # rfc
Link: https://lore.kernel.org/r/166732029577.3186319.17162612653237909961.stgit@warthog.procyon.org.uk/

 # rfc
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent e5fbdde4

fs/cifs/cifsencrypt.c

+144 −0
Original line number Diff line number Diff line
@@ -24,6 +24,150 @@ 
#include "../smbfs_common/arc4.h"

#include <crypto/aead.h>



/*

 * Hash data from a BVEC-type iterator.

 */

static int cifs_shash_bvec(const struct iov_iter *iter, ssize_t maxsize,

			   struct shash_desc *shash)

{

	const struct bio_vec *bv = iter->bvec;

	unsigned long start = iter->iov_offset;

	unsigned int i;

	void *p;

	int ret;



	for (i = 0; i < iter->nr_segs; i++) {

		size_t off, len;



		len = bv[i].bv_len;

		if (start >= len) {

			start -= len;

			continue;

		}



		len = min_t(size_t, maxsize, len - start);

		off = bv[i].bv_offset + start;



		p = kmap_local_page(bv[i].bv_page);

		ret = crypto_shash_update(shash, p + off, len);

		kunmap_local(p);

		if (ret < 0)

			return ret;



		maxsize -= len;

		if (maxsize <= 0)

			break;

		start = 0;

	}



	return 0;

}



/*

 * Hash data from a KVEC-type iterator.

 */

static int cifs_shash_kvec(const struct iov_iter *iter, ssize_t maxsize,

			   struct shash_desc *shash)

{

	const struct kvec *kv = iter->kvec;

	unsigned long start = iter->iov_offset;

	unsigned int i;

	int ret;



	for (i = 0; i < iter->nr_segs; i++) {

		size_t len;



		len = kv[i].iov_len;

		if (start >= len) {

			start -= len;

			continue;

		}



		len = min_t(size_t, maxsize, len - start);

		ret = crypto_shash_update(shash, kv[i].iov_base + start, len);

		if (ret < 0)

			return ret;

		maxsize -= len;



		if (maxsize <= 0)

			break;

		start = 0;

	}



	return 0;

}



/*

 * Hash data from an XARRAY-type iterator.

 */

static ssize_t cifs_shash_xarray(const struct iov_iter *iter, ssize_t maxsize,

				 struct shash_desc *shash)

{

	struct folio *folios[16], *folio;

	unsigned int nr, i, j, npages;

	loff_t start = iter->xarray_start + iter->iov_offset;

	pgoff_t last, index = start / PAGE_SIZE;

	ssize_t ret = 0;

	size_t len, offset, foffset;

	void *p;



	if (maxsize == 0)

		return 0;



	last = (start + maxsize - 1) / PAGE_SIZE;

	do {

		nr = xa_extract(iter->xarray, (void **)folios, index, last,

				ARRAY_SIZE(folios), XA_PRESENT);

		if (nr == 0)

			return -EIO;



		for (i = 0; i < nr; i++) {

			folio = folios[i];

			npages = folio_nr_pages(folio);

			foffset = start - folio_pos(folio);

			offset = foffset % PAGE_SIZE;

			for (j = foffset / PAGE_SIZE; j < npages; j++) {

				len = min_t(size_t, maxsize, PAGE_SIZE - offset);

				p = kmap_local_page(folio_page(folio, j));

				ret = crypto_shash_update(shash, p, len);

				kunmap_local(p);

				if (ret < 0)

					return ret;

				maxsize -= len;

				if (maxsize <= 0)

					return 0;

				start += len;

				offset = 0;

				index++;

			}

		}

	} while (nr == ARRAY_SIZE(folios));

	return 0;

}



/*

 * Pass the data from an iterator into a hash.

 */

static int cifs_shash_iter(const struct iov_iter *iter, size_t maxsize,

			   struct shash_desc *shash)

{

	if (maxsize == 0)

		return 0;



	switch (iov_iter_type(iter)) {

	case ITER_BVEC:

		return cifs_shash_bvec(iter, maxsize, shash);

	case ITER_KVEC:

		return cifs_shash_kvec(iter, maxsize, shash);

	case ITER_XARRAY:

		return cifs_shash_xarray(iter, maxsize, shash);

	default:

		pr_err("cifs_shash_iter(%u) unsupported\n", iov_iter_type(iter));

		WARN_ON_ONCE(1);

		return -EIO;

	}

}



int __cifs_calc_signature(struct smb_rqst *rqst,

			struct TCP_Server_Info *server, char *signature,

			struct shash_desc *shash)