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Registered in England and Wales under Company Registration No. 3798903 Subject: [RFC PATCH 4/9] cifs: Add a function to Hash the contents of an iterator From: David Howells To: Steve French , Al Viro Cc: dhowells@redhat.com, Shyam Prasad N , Rohith Surabattula , Tom Talpey , Christoph Hellwig , Matthew Wilcox , Jeff Layton , linux-cifs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Date: Fri, 28 Oct 2022 16:56:14 +0100 Message-ID: <166697257423.61150.12070648579830206483.stgit@warthog.procyon.org.uk> In-Reply-To: <166697254399.61150.1256557652599252121.stgit@warthog.procyon.org.uk> References: <166697254399.61150.1256557652599252121.stgit@warthog.procyon.org.uk> User-Agent: StGit/1.5 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.7 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add a function to push the contents of a BVEC-, KVEC- or XARRAY-type iterator into a symmetric 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: David Howells --- fs/cifs/cifsencrypt.c | 139 +++++++++++++++++++++++++++++++++++++++++++++= ++++ 1 file changed, 139 insertions(+) diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c index 5db73c0f792a..f7d1843b4671 100644 --- a/fs/cifs/cifsencrypt.c +++ b/fs/cifs/cifsencrypt.c @@ -24,6 +24,145 @@ #include "../smbfs_common/arc4.h" #include =20 +/* + * 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 =3D iter->bvec; + unsigned long start =3D iter->iov_offset; + unsigned int i; + void *p; + int ret; + + for (i =3D 0; i < iter->nr_segs; i++) { + size_t off, len; + + len =3D bv[i].bv_len; + if (start >=3D len) { + start -=3D len; + continue; + } + + len =3D min_t(size_t, maxsize, len - start); + off =3D bv[i].bv_offset + start; + + p =3D kmap_local_page(bv[i].bv_page); + ret =3D crypto_shash_update(shash, p + off, len); + kunmap_local(p); + if (ret < 0) + return ret; + + maxsize -=3D len; + if (maxsize <=3D 0) + break; + start =3D 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 =3D iter->kvec; + unsigned long start =3D iter->iov_offset; + unsigned int i; + int ret; + + for (i =3D 0; i < iter->nr_segs; i++) { + size_t len; + + len =3D kv[i].iov_len; + if (start >=3D len) { + start -=3D len; + continue; + } + + len =3D min_t(size_t, maxsize, len - start); + ret =3D crypto_shash_update(shash, kv[i].iov_base + start, len); + if (ret < 0) + return ret; + maxsize -=3D len; + + if (maxsize <=3D 0) + break; + start =3D 0; + } + + return 0; +} + +/* + * Hash data from an XARRAY-type iterator. + */ +static ssize_t cifs_shash_xarray(const struct iov_iter *iter, ssize_t maxs= ize, + struct shash_desc *shash) +{ + struct xarray *xa =3D iter->xarray; + struct folio *folio; + loff_t start =3D iter->xarray_start + iter->iov_offset; + pgoff_t index =3D start / PAGE_SIZE; + ssize_t ret =3D 0; + size_t offset, len; + void *p; + XA_STATE(xas, xa, index); + + rcu_read_lock(); + + xas_for_each(&xas, folio, ULONG_MAX) { + if (xas_retry(&xas, folio)) + continue; + if (WARN_ON(xa_is_value(folio))) + break; + if (WARN_ON(folio_test_hugetlb(folio))) + break; + + offset =3D offset_in_folio(folio, start); + len =3D min_t(size_t, maxsize, folio_size(folio) - offset); + + p =3D kmap_local_folio(folio, offset); + ret =3D crypto_shash_update(shash, p, len); + kunmap_local(p); + if (ret < 0) + break; + + maxsize -=3D len; + if (maxsize <=3D 0) + break; + } + + rcu_read_unlock(); + return ret; +} + +/* + * 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 =3D=3D 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)