[PATCH v8 01/10] iov_iter: add copy_struct_from_iter()
From: Omar Sandoval
This is essentially copy_struct_from_user() but for an iov_iter.
Suggested-by: Aleksa Sarai
Reviewed-by: Josef Bacik
Signed-off-by: Omar Sandoval
---
include/linux/uio.h | 2 ++
lib/iov_iter.c | 82 +
2 files changed, 84 insertions(+)
diff --git a/include/linux/uio.h b/include/linux/uio.h
index 72d88566694e..f4e6ea85a269 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -121,6 +121,8 @@ size_t copy_page_to_iter(struct page *page, size_t offset,
size_t bytes,
struct iov_iter *i);
size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
struct iov_iter *i);
+int copy_struct_from_iter(void *dst, size_t ksize, struct iov_iter *i,
+ size_t usize);
size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i);
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index a21e6a5792c5..f45826ed7528 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -948,6 +948,88 @@ size_t copy_page_from_iter(struct page *page, size_t
offset, size_t bytes,
}
EXPORT_SYMBOL(copy_page_from_iter);
+/**
+ * copy_struct_from_iter - copy a struct from an iov_iter
+ * @dst: Destination buffer.
+ * @ksize: Size of @dst struct.
+ * @i: Source iterator.
+ * @usize: (Alleged) size of struct in @i.
+ *
+ * Copies a struct from an iov_iter in a way that guarantees
+ * backwards-compatibility for struct arguments in an iovec (as long as the
+ * rules for copy_struct_from_user() are followed).
+ *
+ * The recommended usage is that @usize be taken from the current segment:
+ *
+ * int do_foo(struct iov_iter *i)
+ * {
+ * size_t usize = iov_iter_single_seg_count(i);
+ * struct foo karg;
+ * int err;
+ *
+ * if (usize > PAGE_SIZE)
+ * return -E2BIG;
+ * if (usize < FOO_SIZE_VER0)
+ * return -EINVAL;
+ * err = copy_struct_from_iter(&karg, sizeof(karg), i, usize);
+ * if (err)
+ * return err;
+ *
+ * // ...
+ * }
+ *
+ * Return: 0 on success, -errno on error (see copy_struct_from_user()).
+ *
+ * On success, the iterator is advanced @usize bytes. On error, the iterator is
+ * not advanced.
+ */
+int copy_struct_from_iter(void *dst, size_t ksize, struct iov_iter *i,
+ size_t usize)
+{
+ if (usize <= ksize) {
+ if (!copy_from_iter_full(dst, usize, i))
+ return -EFAULT;
+ memset(dst + usize, 0, ksize - usize);
+ } else {
+ size_t copied = 0, copy;
+ int ret;
+
+ if (WARN_ON(iov_iter_is_pipe(i)) || unlikely(i->count < usize))
+ return -EFAULT;
+ if (iter_is_iovec(i))
+ might_fault();
+ iterate_all_kinds(i, usize, v, ({
+ copy = min(ksize - copied, v.iov_len);
+ if (copy && copyin(dst + copied, v.iov_base, copy))
+ return -EFAULT;
+ copied += copy;
+ ret = check_zeroed_user(v.iov_base + copy,
+ v.iov_len - copy);
+ if (ret <= 0)
+ return ret ?: -E2BIG;
+ 0;}), ({
+ char *addr = kmap_atomic(v.bv_page);
+ copy = min_t(size_t, ksize - copied, v.bv_len);
+ memcpy(dst + copied, addr + v.bv_offset, copy);
+ copied += copy;
+ ret = memchr_inv(addr + v.bv_offset + copy, 0,
+v.bv_len - copy) ? -E2BIG : 0;
+ kunmap_atomic(addr);
+ if (ret)
+ return ret;
+ }), ({
+ copy = min(ksize - copied, v.iov_len);
+ memcpy(dst + copied, v.iov_base, copy);
+ if (memchr_inv(v.iov_base, 0, v.iov_len))
+ return -E2BIG;
+ })
+ )
+ iov_iter_advance(i, usize);
+ }
+ return 0;
+}
+EXPORT_SYMBOL_GPL(copy_struct_from_iter);
+
static size_t pipe_zero(size_t bytes, struct iov_iter *i)
{
struct pipe_inode_info *pipe = i->pipe;
--
2.30.2
Re: [PATCH v8 01/10] iov_iter: add copy_struct_from_iter()
On Tue, Mar 16, 2021 at 12:42:57PM -0700, Omar Sandoval wrote:
> From: Omar Sandoval
>
> This is essentially copy_struct_from_user() but for an iov_iter.
>
> Suggested-by: Aleksa Sarai
> Reviewed-by: Josef Bacik
> Signed-off-by: Omar Sandoval
> ---
> include/linux/uio.h | 2 ++
> lib/iov_iter.c | 82 +
> 2 files changed, 84 insertions(+)
>
> diff --git a/include/linux/uio.h b/include/linux/uio.h
> index 72d88566694e..f4e6ea85a269 100644
> --- a/include/linux/uio.h
> +++ b/include/linux/uio.h
> @@ -121,6 +121,8 @@ size_t copy_page_to_iter(struct page *page, size_t
> offset, size_t bytes,
>struct iov_iter *i);
> size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
>struct iov_iter *i);
> +int copy_struct_from_iter(void *dst, size_t ksize, struct iov_iter *i,
> + size_t usize);
>
> size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
> size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i);
> diff --git a/lib/iov_iter.c b/lib/iov_iter.c
> index a21e6a5792c5..f45826ed7528 100644
> --- a/lib/iov_iter.c
> +++ b/lib/iov_iter.c
> @@ -948,6 +948,88 @@ size_t copy_page_from_iter(struct page *page, size_t
> offset, size_t bytes,
> }
> EXPORT_SYMBOL(copy_page_from_iter);
>
> +/**
> + * copy_struct_from_iter - copy a struct from an iov_iter
> + * @dst: Destination buffer.
> + * @ksize: Size of @dst struct.
> + * @i: Source iterator.
> + * @usize: (Alleged) size of struct in @i.
> + *
> + * Copies a struct from an iov_iter in a way that guarantees
> + * backwards-compatibility for struct arguments in an iovec (as long as the
> + * rules for copy_struct_from_user() are followed).
> + *
> + * The recommended usage is that @usize be taken from the current segment:
> + *
> + * int do_foo(struct iov_iter *i)
> + * {
> + * size_t usize = iov_iter_single_seg_count(i);
> + * struct foo karg;
> + * int err;
> + *
> + * if (usize > PAGE_SIZE)
> + * return -E2BIG;
> + * if (usize < FOO_SIZE_VER0)
> + * return -EINVAL;
> + * err = copy_struct_from_iter(&karg, sizeof(karg), i, usize);
> + * if (err)
> + * return err;
> + *
> + * // ...
> + * }
> + *
> + * Return: 0 on success, -errno on error (see copy_struct_from_user()).
> + *
> + * On success, the iterator is advanced @usize bytes. On error, the iterator
> is
> + * not advanced.
> + */
> +int copy_struct_from_iter(void *dst, size_t ksize, struct iov_iter *i,
> + size_t usize)
> +{
> + if (usize <= ksize) {
> + if (!copy_from_iter_full(dst, usize, i))
> + return -EFAULT;
> + memset(dst + usize, 0, ksize - usize);
> + } else {
> + size_t copied = 0, copy;
> + int ret;
> +
> + if (WARN_ON(iov_iter_is_pipe(i)) || unlikely(i->count < usize))
> + return -EFAULT;
> + if (iter_is_iovec(i))
> + might_fault();
> + iterate_all_kinds(i, usize, v, ({
> + copy = min(ksize - copied, v.iov_len);
> + if (copy && copyin(dst + copied, v.iov_base, copy))
> + return -EFAULT;
> + copied += copy;
> + ret = check_zeroed_user(v.iov_base + copy,
> + v.iov_len - copy);
> + if (ret <= 0)
> + return ret ?: -E2BIG;
> + 0;}), ({
> + char *addr = kmap_atomic(v.bv_page);
> + copy = min_t(size_t, ksize - copied, v.bv_len);
> + memcpy(dst + copied, addr + v.bv_offset, copy);
> + copied += copy;
> + ret = memchr_inv(addr + v.bv_offset + copy, 0,
> + v.bv_len - copy) ? -E2BIG : 0;
> + kunmap_atomic(addr);
> + if (ret)
> + return ret;
> + }), ({
> + copy = min(ksize - copied, v.iov_len);
> + memcpy(dst + copied, v.iov_base, copy);
> + if (memchr_inv(v.iov_base, 0, v.iov_len))
> + return -E2BIG;
> + })
> + )
Following the semantics of copy_struct_from_user() is certainly a good
idea but can this in any way be rewritten to not look like this; at
least not as crammed. It's a bit painful to follow here what's going.
Re: [PATCH v8 01/10] iov_iter: add copy_struct_from_iter()
On Wed, Mar 17, 2021 at 06:56:11PM +0100, Christian Brauner wrote:
> On Tue, Mar 16, 2021 at 12:42:57PM -0700, Omar Sandoval wrote:
> > From: Omar Sandoval
> >
> > This is essentially copy_struct_from_user() but for an iov_iter.
> >
> > Suggested-by: Aleksa Sarai
> > Reviewed-by: Josef Bacik
> > Signed-off-by: Omar Sandoval
> > ---
> > include/linux/uio.h | 2 ++
> > lib/iov_iter.c | 82 +
> > 2 files changed, 84 insertions(+)
> >
> > diff --git a/include/linux/uio.h b/include/linux/uio.h
> > index 72d88566694e..f4e6ea85a269 100644
> > --- a/include/linux/uio.h
> > +++ b/include/linux/uio.h
> > @@ -121,6 +121,8 @@ size_t copy_page_to_iter(struct page *page, size_t
> > offset, size_t bytes,
> > struct iov_iter *i);
> > size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
> > struct iov_iter *i);
> > +int copy_struct_from_iter(void *dst, size_t ksize, struct iov_iter *i,
> > + size_t usize);
> >
> > size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
> > size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i);
> > diff --git a/lib/iov_iter.c b/lib/iov_iter.c
> > index a21e6a5792c5..f45826ed7528 100644
> > --- a/lib/iov_iter.c
> > +++ b/lib/iov_iter.c
> > @@ -948,6 +948,88 @@ size_t copy_page_from_iter(struct page *page, size_t
> > offset, size_t bytes,
> > }
> > EXPORT_SYMBOL(copy_page_from_iter);
> >
> > +/**
> > + * copy_struct_from_iter - copy a struct from an iov_iter
> > + * @dst: Destination buffer.
> > + * @ksize: Size of @dst struct.
> > + * @i: Source iterator.
> > + * @usize: (Alleged) size of struct in @i.
> > + *
> > + * Copies a struct from an iov_iter in a way that guarantees
> > + * backwards-compatibility for struct arguments in an iovec (as long as the
> > + * rules for copy_struct_from_user() are followed).
> > + *
> > + * The recommended usage is that @usize be taken from the current segment:
> > + *
> > + * int do_foo(struct iov_iter *i)
> > + * {
> > + * size_t usize = iov_iter_single_seg_count(i);
> > + * struct foo karg;
> > + * int err;
> > + *
> > + * if (usize > PAGE_SIZE)
> > + * return -E2BIG;
> > + * if (usize < FOO_SIZE_VER0)
> > + * return -EINVAL;
> > + * err = copy_struct_from_iter(&karg, sizeof(karg), i, usize);
> > + * if (err)
> > + * return err;
> > + *
> > + * // ...
> > + * }
> > + *
> > + * Return: 0 on success, -errno on error (see copy_struct_from_user()).
> > + *
> > + * On success, the iterator is advanced @usize bytes. On error, the
> > iterator is
> > + * not advanced.
> > + */
> > +int copy_struct_from_iter(void *dst, size_t ksize, struct iov_iter *i,
> > + size_t usize)
> > +{
> > + if (usize <= ksize) {
> > + if (!copy_from_iter_full(dst, usize, i))
> > + return -EFAULT;
> > + memset(dst + usize, 0, ksize - usize);
> > + } else {
> > + size_t copied = 0, copy;
> > + int ret;
> > +
> > + if (WARN_ON(iov_iter_is_pipe(i)) || unlikely(i->count < usize))
> > + return -EFAULT;
> > + if (iter_is_iovec(i))
> > + might_fault();
> > + iterate_all_kinds(i, usize, v, ({
> > + copy = min(ksize - copied, v.iov_len);
> > + if (copy && copyin(dst + copied, v.iov_base, copy))
> > + return -EFAULT;
> > + copied += copy;
> > + ret = check_zeroed_user(v.iov_base + copy,
> > + v.iov_len - copy);
> > + if (ret <= 0)
> > + return ret ?: -E2BIG;
> > + 0;}), ({
> > + char *addr = kmap_atomic(v.bv_page);
> > + copy = min_t(size_t, ksize - copied, v.bv_len);
> > + memcpy(dst + copied, addr + v.bv_offset, copy);
> > + copied += copy;
> > + ret = memchr_inv(addr + v.bv_offset + copy, 0,
> > +v.bv_len - copy) ? -E2BIG : 0;
> > + kunmap_atomic(addr);
> > + if (ret)
> > + return ret;
> > + }), ({
> > + copy = min(ksize - copied, v.iov_len);
> > + memcpy(dst + copied, v.iov_base, copy);
> > + if (memchr_inv(v.iov_base, 0, v.iov_len))
> > + return -E2BIG;
> > + })
> > + )
>
>
> Following the semantics of copy_struct_from_user() is certainly a good
> idea but can this in any way be rewritten to not look like this; at
> least not as crammed. It's a bit painful to follow here what's going.
I think that's just the nature of the iov_iter code :) I'm just
following the rest of this file, which uses some m
Re: [PATCH v8 01/10] iov_iter: add copy_struct_from_iter()
On Wed, Mar 17, 2021 at 11:45:02AM -0700, Omar Sandoval wrote:
> On Wed, Mar 17, 2021 at 06:56:11PM +0100, Christian Brauner wrote:
> > On Tue, Mar 16, 2021 at 12:42:57PM -0700, Omar Sandoval wrote:
> > > From: Omar Sandoval
> > >
> > > This is essentially copy_struct_from_user() but for an iov_iter.
> > >
> > > Suggested-by: Aleksa Sarai
> > > Reviewed-by: Josef Bacik
> > > Signed-off-by: Omar Sandoval
> > > ---
> > > include/linux/uio.h | 2 ++
> > > lib/iov_iter.c | 82 +
> > > 2 files changed, 84 insertions(+)
> > >
> > > diff --git a/include/linux/uio.h b/include/linux/uio.h
> > > index 72d88566694e..f4e6ea85a269 100644
> > > --- a/include/linux/uio.h
> > > +++ b/include/linux/uio.h
> > > @@ -121,6 +121,8 @@ size_t copy_page_to_iter(struct page *page, size_t
> > > offset, size_t bytes,
> > >struct iov_iter *i);
> > > size_t copy_page_from_iter(struct page *page, size_t offset, size_t
> > > bytes,
> > >struct iov_iter *i);
> > > +int copy_struct_from_iter(void *dst, size_t ksize, struct iov_iter *i,
> > > + size_t usize);
> > >
> > > size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
> > > size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i);
> > > diff --git a/lib/iov_iter.c b/lib/iov_iter.c
> > > index a21e6a5792c5..f45826ed7528 100644
> > > --- a/lib/iov_iter.c
> > > +++ b/lib/iov_iter.c
> > > @@ -948,6 +948,88 @@ size_t copy_page_from_iter(struct page *page, size_t
> > > offset, size_t bytes,
> > > }
> > > EXPORT_SYMBOL(copy_page_from_iter);
> > >
> > > +/**
> > > + * copy_struct_from_iter - copy a struct from an iov_iter
> > > + * @dst: Destination buffer.
> > > + * @ksize: Size of @dst struct.
> > > + * @i: Source iterator.
> > > + * @usize: (Alleged) size of struct in @i.
> > > + *
> > > + * Copies a struct from an iov_iter in a way that guarantees
> > > + * backwards-compatibility for struct arguments in an iovec (as long as
> > > the
> > > + * rules for copy_struct_from_user() are followed).
> > > + *
> > > + * The recommended usage is that @usize be taken from the current
> > > segment:
> > > + *
> > > + * int do_foo(struct iov_iter *i)
> > > + * {
> > > + * size_t usize = iov_iter_single_seg_count(i);
> > > + * struct foo karg;
> > > + * int err;
> > > + *
> > > + * if (usize > PAGE_SIZE)
> > > + * return -E2BIG;
> > > + * if (usize < FOO_SIZE_VER0)
> > > + * return -EINVAL;
> > > + * err = copy_struct_from_iter(&karg, sizeof(karg), i, usize);
> > > + * if (err)
> > > + * return err;
> > > + *
> > > + * // ...
> > > + * }
> > > + *
> > > + * Return: 0 on success, -errno on error (see copy_struct_from_user()).
> > > + *
> > > + * On success, the iterator is advanced @usize bytes. On error, the
> > > iterator is
> > > + * not advanced.
> > > + */
> > > +int copy_struct_from_iter(void *dst, size_t ksize, struct iov_iter *i,
> > > + size_t usize)
> > > +{
> > > + if (usize <= ksize) {
> > > + if (!copy_from_iter_full(dst, usize, i))
> > > + return -EFAULT;
> > > + memset(dst + usize, 0, ksize - usize);
> > > + } else {
> > > + size_t copied = 0, copy;
> > > + int ret;
> > > +
> > > + if (WARN_ON(iov_iter_is_pipe(i)) || unlikely(i->count < usize))
> > > + return -EFAULT;
> > > + if (iter_is_iovec(i))
> > > + might_fault();
> > > + iterate_all_kinds(i, usize, v, ({
> > > + copy = min(ksize - copied, v.iov_len);
> > > + if (copy && copyin(dst + copied, v.iov_base, copy))
> > > + return -EFAULT;
> > > + copied += copy;
> > > + ret = check_zeroed_user(v.iov_base + copy,
> > > + v.iov_len - copy);
> > > + if (ret <= 0)
> > > + return ret ?: -E2BIG;
> > > + 0;}), ({
> > > + char *addr = kmap_atomic(v.bv_page);
> > > + copy = min_t(size_t, ksize - copied, v.bv_len);
> > > + memcpy(dst + copied, addr + v.bv_offset, copy);
> > > + copied += copy;
> > > + ret = memchr_inv(addr + v.bv_offset + copy, 0,
> > > + v.bv_len - copy) ? -E2BIG : 0;
> > > + kunmap_atomic(addr);
> > > + if (ret)
> > > + return ret;
> > > + }), ({
> > > + copy = min(ksize - copied, v.iov_len);
> > > + memcpy(dst + copied, v.iov_base, copy);
> > > + if (memchr_inv(v.iov_base, 0, v.iov_len))
> > > + return -E2BIG;
> > > + })
> > > + )
> >
> >
> > Following the semantics of copy_struct_from_user() is certainly a good
> > idea but can this
