| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <20220827083607.2345453-4-jhubbard@nvidia.com>
Date: Sat, 27 Aug 2022 01:36:04 -0700
From: John Hubbard <jhubbard@...dia.com>
To: Andrew Morton <akpm@...ux-foundation.org>
CC: Jens Axboe <axboe@...nel.dk>,
Alexander Viro <viro@...iv.linux.org.uk>,
Miklos Szeredi <miklos@...redi.hu>,
Christoph Hellwig <hch@...radead.org>,
"Darrick J . Wong" <djwong@...nel.org>,
Trond Myklebust <trond.myklebust@...merspace.com>,
Anna Schumaker <anna@...nel.org>, Jan Kara <jack@...e.cz>,
Logan Gunthorpe <logang@...tatee.com>,
<linux-block@...r.kernel.org>, <linux-fsdevel@...r.kernel.org>,
<linux-xfs@...r.kernel.org>, <linux-nfs@...r.kernel.org>,
<linux-mm@...ck.org>, LKML <linux-kernel@...r.kernel.org>,
John Hubbard <jhubbard@...dia.com>
Subject: [PATCH 3/6] iov_iter: new iov_iter_pin_pages*() routines
Provide two new wrapper routines that are intended for user space pages
only:
iov_iter_pin_pages()
iov_iter_pin_pages_alloc()
Internally, these routines call pin_user_pages_fast(), instead of
get_user_pages_fast().
As always, callers must use unpin_user_pages() or a suitable FOLL_PIN
variant, to release the pages, if they actually were acquired via
pin_user_pages_fast().
This is a prerequisite to converting bio/block layers over to use
pin_user_pages_fast().
Signed-off-by: John Hubbard <jhubbard@...dia.com>
---
include/linux/uio.h | 4 +++
lib/iov_iter.c | 74 ++++++++++++++++++++++++++++++++++++++++++---
2 files changed, 74 insertions(+), 4 deletions(-)
diff --git a/include/linux/uio.h b/include/linux/uio.h
index 5896af36199c..e26908e443d1 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -251,6 +251,10 @@ ssize_t iov_iter_get_pages2(struct iov_iter *i, struct page **pages,
size_t maxsize, unsigned maxpages, size_t *start);
ssize_t iov_iter_get_pages_alloc2(struct iov_iter *i, struct page ***pages,
size_t maxsize, size_t *start);
+ssize_t iov_iter_pin_pages(struct iov_iter *i, struct page **pages,
+ size_t maxsize, unsigned int maxpages, size_t *start);
+ssize_t iov_iter_pin_pages_alloc(struct iov_iter *i, struct page ***pages,
+ size_t maxsize, size_t *start);
int iov_iter_npages(const struct iov_iter *i, int maxpages);
void iov_iter_restore(struct iov_iter *i, struct iov_iter_state *state);
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 4b7fce72e3e5..1c08014c8498 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1425,9 +1425,23 @@ static struct page *first_bvec_segment(const struct iov_iter *i,
return page;
}
+enum pages_alloc_internal_flags {
+ USE_FOLL_GET,
+ USE_FOLL_PIN
+};
+
+/*
+ * TODO: get rid of the how_to_pin arg, and just call pin_user_pages_fast()
+ * unconditionally for the user_back_iter(i) case in this function. That can be
+ * done once all callers are ready to deal with FOLL_PIN pages for their
+ * user-space pages. (FOLL_PIN pages must be released via unpin_user_page(),
+ * rather than put_page().)
+ */
static ssize_t __iov_iter_get_pages_alloc(struct iov_iter *i,
struct page ***pages, size_t maxsize,
- unsigned int maxpages, size_t *start)
+ unsigned int maxpages, size_t *start,
+ enum pages_alloc_internal_flags how_to_pin)
+
{
unsigned int n;
@@ -1454,7 +1468,12 @@ static ssize_t __iov_iter_get_pages_alloc(struct iov_iter *i,
n = want_pages_array(pages, maxsize, *start, maxpages);
if (!n)
return -ENOMEM;
- res = get_user_pages_fast(addr, n, gup_flags, *pages);
+
+ if (how_to_pin == USE_FOLL_PIN)
+ res = pin_user_pages_fast(addr, n, gup_flags, *pages);
+ else
+ res = get_user_pages_fast(addr, n, gup_flags, *pages);
+
if (unlikely(res <= 0))
return res;
maxsize = min_t(size_t, maxsize, res * PAGE_SIZE - *start);
@@ -1497,10 +1516,31 @@ ssize_t iov_iter_get_pages2(struct iov_iter *i,
return 0;
BUG_ON(!pages);
- return __iov_iter_get_pages_alloc(i, &pages, maxsize, maxpages, start);
+ return __iov_iter_get_pages_alloc(i, &pages, maxsize, maxpages, start,
+ USE_FOLL_GET);
}
EXPORT_SYMBOL(iov_iter_get_pages2);
+/*
+ * A FOLL_PIN variant that calls pin_user_pages_fast() instead of
+ * get_user_pages_fast().
+ */
+ssize_t iov_iter_pin_pages(struct iov_iter *i,
+ struct page **pages, size_t maxsize, unsigned int maxpages,
+ size_t *start)
+{
+ if (!maxpages)
+ return 0;
+ if (WARN_ON_ONCE(!pages))
+ return -EINVAL;
+ if (WARN_ON_ONCE(!user_backed_iter(i)))
+ return -EINVAL;
+
+ return __iov_iter_get_pages_alloc(i, &pages, maxsize, maxpages, start,
+ USE_FOLL_PIN);
+}
+EXPORT_SYMBOL(iov_iter_pin_pages);
+
ssize_t iov_iter_get_pages_alloc2(struct iov_iter *i,
struct page ***pages, size_t maxsize,
size_t *start)
@@ -1509,7 +1549,8 @@ ssize_t iov_iter_get_pages_alloc2(struct iov_iter *i,
*pages = NULL;
- len = __iov_iter_get_pages_alloc(i, pages, maxsize, ~0U, start);
+ len = __iov_iter_get_pages_alloc(i, pages, maxsize, ~0U, start,
+ USE_FOLL_GET);
if (len <= 0) {
kvfree(*pages);
*pages = NULL;
@@ -1518,6 +1559,31 @@ ssize_t iov_iter_get_pages_alloc2(struct iov_iter *i,
}
EXPORT_SYMBOL(iov_iter_get_pages_alloc2);
+/*
+ * A FOLL_PIN variant that calls pin_user_pages_fast() instead of
+ * get_user_pages_fast().
+ */
+ssize_t iov_iter_pin_pages_alloc(struct iov_iter *i,
+ struct page ***pages, size_t maxsize,
+ size_t *start)
+{
+ ssize_t len;
+
+ *pages = NULL;
+
+ if (WARN_ON_ONCE(!user_backed_iter(i)))
+ return -EINVAL;
+
+ len = __iov_iter_get_pages_alloc(i, pages, maxsize, ~0U, start,
+ USE_FOLL_PIN);
+ if (len <= 0) {
+ kvfree(*pages);
+ *pages = NULL;
+ }
+ return len;
+}
+EXPORT_SYMBOL(iov_iter_pin_pages_alloc);
+
size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum,
struct iov_iter *i)
{
--
2.37.2
Powered by blists - more mailing lists