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 <dhowells@xxxxxxxxxx> cc: Steve French <sfrench@xxxxxxxxx> cc: Shyam Prasad N <nspmangalore@xxxxxxxxx> cc: Rohith Surabattula <rohiths.msft@xxxxxxxxx> cc: Jeff Layton <jlayton@xxxxxxxxxx> cc: linux-cifs@xxxxxxxxxxxxxxx cc: linux-fsdevel@xxxxxxxxxxxxxxx cc: linux-crypto@xxxxxxxxxxxxxxx Link: https://lore.kernel.org/r/166697257423.61150.12070648579830206483.stgit@xxxxxxxxxxxxxxxxxxxxxx/ # rfc Link: https://lore.kernel.org/r/166732029577.3186319.17162612653237909961.stgit@xxxxxxxxxxxxxxxxxxxxxx/ # rfc --- fs/cifs/cifsencrypt.c | 144 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 144 insertions(+) diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c index 5db73c0f792a..e13f26371540 100644 --- a/fs/cifs/cifsencrypt.c +++ b/fs/cifs/cifsencrypt.c @@ -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)
