From 3a2c4d55e32ad65efebdb6de44eef3bfa08bb49d Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Wed, 2 Sep 2026 15:31:14 -0700 Subject: treewide: refresh kmalloc_obj() conversions This is another run of the Coccinelle script for converting kmalloc() family of allocations to kmalloc_obj() via the existing rules in scripts/coccinelle/api/kmalloc_objs.cocci This catches both the set of kmalloc() uses added since the first kmalloc_obj() conversions in v7.0 and adds a large group missed in the first pass due to Coccinelle not interacting well with the cleanup.h scoped_...() family of macros[1]. I worked around this with spatch's "--macro-file" argument to a file with all the scoped_...() macros mapped to Coccinelle's YACFE_ITERATOR[2] as that was the closest viable control flow indicator I could find. Build tested allmodconfig on x86, arm64, arm, loongarch, mips, powerpc, riscv, and s390 with no new warnings. Link: https://lore.kernel.org/lkml/202609021314.8A9C0B8@keescook/ [1] Link: https://github.com/coccinelle/coccinelle/blob/master/standard.h [2] Signed-off-by: Kees Cook --- fs/netfs/iterator.c | 308 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 308 insertions(+) create mode 100644 fs/netfs/iterator.c (limited to 'fs/netfs/iterator.c') diff --git a/fs/netfs/iterator.c b/fs/netfs/iterator.c new file mode 100644 index 000000000..b375567e0 --- /dev/null +++ b/fs/netfs/iterator.c @@ -0,0 +1,308 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* Iterator helpers. + * + * Copyright (C) 2022 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#include +#include +#include +#include +#include +#include +#include "internal.h" + +/** + * netfs_extract_user_iter - Extract the pages from a user iterator into a bvec + * @orig: The original iterator + * @orig_len: The amount of iterator to copy + * @new: The iterator to be set up + * @extraction_flags: Flags to qualify the request + * + * Extract the page fragments from the given amount of the source iterator and + * build up a second iterator that refers to all of those bits. This allows + * the original iterator to be disposed of. + * + * @extraction_flags can have ITER_ALLOW_P2PDMA set to request peer-to-peer DMA be + * allowed on the pages extracted. + * + * On success, the number of elements in the bvec is returned, the original + * iterator will have been advanced by the amount extracted. + * + * The iov_iter_extract_mode() function should be used to query how cleanup + * should be performed. + */ +ssize_t netfs_extract_user_iter(struct iov_iter *orig, size_t orig_len, + struct iov_iter *new, + iov_iter_extraction_t extraction_flags) +{ + struct bio_vec *bv = NULL; + struct page **pages; + unsigned int cur_npages; + unsigned int max_pages; + unsigned int npages = 0; + unsigned int i; + ssize_t ret = 0; + size_t count = orig_len, offset, len; + size_t bv_size, pg_size; + + if (WARN_ON_ONCE(!iter_is_ubuf(orig) && !iter_is_iovec(orig))) + return -EIO; + + max_pages = iov_iter_npages(orig, INT_MAX); + bv_size = array_size(max_pages, sizeof(*bv)); + bv = kvmalloc(bv_size, GFP_KERNEL); + if (!bv) + return -ENOMEM; + + /* Put the page list at the end of the bvec list storage. bvec + * elements are larger than page pointers, so as long as we work + * 0->last, we should be fine. + */ + pg_size = array_size(max_pages, sizeof(*pages)); + pages = (void *)bv + bv_size - pg_size; + + while (count && npages < max_pages) { + ret = iov_iter_extract_pages(orig, &pages, count, + max_pages - npages, extraction_flags, + &offset); + if (unlikely(ret <= 0)) { + ret = ret ?: -EIO; + break; + } + + if (WARN(ret > count, + "%s: extract_pages overrun %zd > %zu bytes\n", + __func__, ret, count)) { + ret = -EIO; + break; + } + + cur_npages = DIV_ROUND_UP(offset + ret, PAGE_SIZE); + if (WARN(cur_npages > max_pages - npages, + "%s: extract_pages overrun %u > %u pages\n", + __func__, npages + cur_npages, max_pages)) { + ret = -EIO; + break; + } + + count -= ret; + ret += offset; + + for (i = 0; i < cur_npages; i++) { + len = ret > PAGE_SIZE ? PAGE_SIZE : ret; + bvec_set_page(bv + npages + i, *pages++, len - offset, offset); + ret -= len; + offset = 0; + } + + npages += cur_npages; + } + + /* Note: Don't try to clean up after EIO. Either we got no pages, so + * nothing to clean up, or we got a buffer overrun, memory corruption + * and can't trust the stuff in the buffer (a WARN was emitted). + */ + + if (ret < 0 && (ret == -ENOMEM || npages == 0)) { + for (i = 0; i < npages; i++) + unpin_user_page(bv[i].bv_page); + kvfree(bv); + return ret; + } + + iov_iter_bvec(new, orig->data_source, bv, npages, orig_len - count); + return npages; +} +EXPORT_SYMBOL_GPL(netfs_extract_user_iter); + +/* + * Select the span of a bvec iterator we're going to use. Limit it by both maximum + * size and maximum number of segments. Returns the size of the span in bytes. + */ +static size_t netfs_limit_bvec(const struct iov_iter *iter, size_t start_offset, + size_t max_size, size_t max_segs) +{ + const struct bio_vec *bvecs = iter->bvec; + unsigned int nbv = iter->nr_segs, ix = 0, nsegs = 0; + size_t len, span = 0, n = iter->count; + size_t skip = iter->iov_offset + start_offset; + + if (WARN_ON(!iov_iter_is_bvec(iter)) || + WARN_ON(start_offset > n) || + n == 0) + return 0; + + while (n && ix < nbv && skip) { + len = bvecs[ix].bv_len; + if (skip < len) + break; + skip -= len; + n -= len; + ix++; + } + + while (n && ix < nbv) { + len = min3(n, bvecs[ix].bv_len - skip, max_size); + span += len; + nsegs++; + ix++; + if (span >= max_size || nsegs >= max_segs) + break; + skip = 0; + n -= len; + } + + return min(span, max_size); +} + +/* + * Select the span of a kvec iterator we're going to use. Limit it by both + * maximum size and maximum number of segments. Returns the size of the span + * in bytes. + */ +static size_t netfs_limit_kvec(const struct iov_iter *iter, size_t start_offset, + size_t max_size, size_t max_segs) +{ + const struct kvec *kvecs = iter->kvec; + unsigned int nkv = iter->nr_segs, ix = 0, nsegs = 0; + size_t len, span = 0, n = iter->count; + size_t skip = iter->iov_offset + start_offset; + + if (WARN_ON(!iov_iter_is_kvec(iter)) || + WARN_ON(start_offset > n) || + n == 0) + return 0; + + while (n && ix < nkv && skip) { + len = kvecs[ix].iov_len; + if (skip < len) + break; + skip -= len; + n -= len; + ix++; + } + + while (n && ix < nkv) { + len = min3(n, kvecs[ix].iov_len - skip, max_size); + span += len; + nsegs++; + ix++; + if (span >= max_size || nsegs >= max_segs) + break; + skip = 0; + n -= len; + } + + return min(span, max_size); +} + +/* + * Select the span of an xarray iterator we're going to use. Limit it by both + * maximum size and maximum number of segments. It is assumed that segments + * can be larger than a page in size, provided they're physically contiguous. + * Returns the size of the span in bytes. + */ +static size_t netfs_limit_xarray(const struct iov_iter *iter, size_t start_offset, + size_t max_size, size_t max_segs) +{ + struct folio *folio; + unsigned int nsegs = 0; + loff_t pos = iter->xarray_start + iter->iov_offset; + pgoff_t index = pos / PAGE_SIZE; + size_t span = 0, n = iter->count; + + XA_STATE(xas, iter->xarray, index); + + if (WARN_ON(!iov_iter_is_xarray(iter)) || + WARN_ON(start_offset > n) || + n == 0) + return 0; + max_size = min(max_size, n - start_offset); + + rcu_read_lock(); + xas_for_each(&xas, folio, ULONG_MAX) { + size_t offset, flen, len; + if (xas_retry(&xas, folio)) + continue; + if (WARN_ON(xa_is_value(folio))) + break; + if (WARN_ON(folio_test_hugetlb(folio))) + break; + + flen = folio_size(folio); + offset = offset_in_folio(folio, pos); + len = min(max_size, flen - offset); + span += len; + nsegs++; + if (span >= max_size || nsegs >= max_segs) + break; + } + + rcu_read_unlock(); + return min(span, max_size); +} + +/* + * Select the span of a folio queue iterator we're going to use. Limit it by + * both maximum size and maximum number of segments. Returns the size of the + * span in bytes. + */ +static size_t netfs_limit_folioq(const struct iov_iter *iter, size_t start_offset, + size_t max_size, size_t max_segs) +{ + const struct folio_queue *folioq = iter->folioq; + unsigned int nsegs = 0; + unsigned int slot = iter->folioq_slot; + size_t span = 0, n = iter->count; + + if (WARN_ON(!iov_iter_is_folioq(iter)) || + WARN_ON(start_offset > n) || + n == 0) + return 0; + max_size = umin(max_size, n - start_offset); + + if (slot >= folioq_nr_slots(folioq)) { + folioq = folioq->next; + slot = 0; + } + + start_offset += iter->iov_offset; + do { + size_t flen = folioq_folio_size(folioq, slot); + + if (start_offset < flen) { + span += flen - start_offset; + nsegs++; + start_offset = 0; + } else { + start_offset -= flen; + } + if (span >= max_size || nsegs >= max_segs) + break; + + slot++; + if (slot >= folioq_nr_slots(folioq)) { + folioq = folioq->next; + slot = 0; + } + } while (folioq); + + return umin(span, max_size); +} + +size_t netfs_limit_iter(const struct iov_iter *iter, size_t start_offset, + size_t max_size, size_t max_segs) +{ + if (iov_iter_is_folioq(iter)) + return netfs_limit_folioq(iter, start_offset, max_size, max_segs); + if (iov_iter_is_bvec(iter)) + return netfs_limit_bvec(iter, start_offset, max_size, max_segs); + if (iov_iter_is_xarray(iter)) + return netfs_limit_xarray(iter, start_offset, max_size, max_segs); + if (iov_iter_is_kvec(iter)) + return netfs_limit_kvec(iter, start_offset, max_size, max_segs); + BUG(); +} +EXPORT_SYMBOL(netfs_limit_iter); -- cgit v1.3.1