we can do copyin/copyout under kmap_local_page(); it shouldn't overflow
the kmap stack - the maximal footprint increase only by one here.
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
---
lib/iov_iter.c | 191 ++-----------------------------------------------
1 file changed, 4 insertions(+), 187 deletions(-)
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 6dd5330f7a99..4c658a25e29c 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -168,174 +168,6 @@ static int copyin(void *to, const void __user *from, size_t n)
return n;
}
-static size_t copy_page_to_iter_iovec(struct page *page, size_t offset, size_t bytes,
- struct iov_iter *i)
-{
- size_t skip, copy, left, wanted;
- const struct iovec *iov;
- char __user *buf;
- void *kaddr, *from;
-
- if (unlikely(bytes > i->count))
- bytes = i->count;
-
- if (unlikely(!bytes))
- return 0;
-
- might_fault();
- wanted = bytes;
- iov = i->iov;
- skip = i->iov_offset;
- buf = iov->iov_base + skip;
- copy = min(bytes, iov->iov_len - skip);
-
- if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_writeable(buf, copy)) {
- kaddr = kmap_atomic(page);
- from = kaddr + offset;
-
- /* first chunk, usually the only one */
- left = copyout(buf, from, copy);
- copy -= left;
- skip += copy;
- from += copy;
- bytes -= copy;
-
- while (unlikely(!left && bytes)) {
- iov++;
- buf = iov->iov_base;
- copy = min(bytes, iov->iov_len);
- left = copyout(buf, from, copy);
- copy -= left;
- skip = copy;
- from += copy;
- bytes -= copy;
- }
- if (likely(!bytes)) {
- kunmap_atomic(kaddr);
- goto done;
- }
- offset = from - kaddr;
- buf += copy;
- kunmap_atomic(kaddr);
- copy = min(bytes, iov->iov_len - skip);
- }
- /* Too bad - revert to non-atomic kmap */
-
- kaddr = kmap(page);
- from = kaddr + offset;
- left = copyout(buf, from, copy);
- copy -= left;
- skip += copy;
- from += copy;
- bytes -= copy;
- while (unlikely(!left && bytes)) {
- iov++;
- buf = iov->iov_base;
- copy = min(bytes, iov->iov_len);
- left = copyout(buf, from, copy);
- copy -= left;
- skip = copy;
- from += copy;
- bytes -= copy;
- }
- kunmap(page);
-
-done:
- if (skip == iov->iov_len) {
- iov++;
- skip = 0;
- }
- i->count -= wanted - bytes;
- i->nr_segs -= iov - i->iov;
- i->iov = iov;
- i->iov_offset = skip;
- return wanted - bytes;
-}
-
-static size_t copy_page_from_iter_iovec(struct page *page, size_t offset, size_t bytes,
- struct iov_iter *i)
-{
- size_t skip, copy, left, wanted;
- const struct iovec *iov;
- char __user *buf;
- void *kaddr, *to;
-
- if (unlikely(bytes > i->count))
- bytes = i->count;
-
- if (unlikely(!bytes))
- return 0;
-
- might_fault();
- wanted = bytes;
- iov = i->iov;
- skip = i->iov_offset;
- buf = iov->iov_base + skip;
- copy = min(bytes, iov->iov_len - skip);
-
- if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_readable(buf, copy)) {
- kaddr = kmap_atomic(page);
- to = kaddr + offset;
-
- /* first chunk, usually the only one */
- left = copyin(to, buf, copy);
- copy -= left;
- skip += copy;
- to += copy;
- bytes -= copy;
-
- while (unlikely(!left && bytes)) {
- iov++;
- buf = iov->iov_base;
- copy = min(bytes, iov->iov_len);
- left = copyin(to, buf, copy);
- copy -= left;
- skip = copy;
- to += copy;
- bytes -= copy;
- }
- if (likely(!bytes)) {
- kunmap_atomic(kaddr);
- goto done;
- }
- offset = to - kaddr;
- buf += copy;
- kunmap_atomic(kaddr);
- copy = min(bytes, iov->iov_len - skip);
- }
- /* Too bad - revert to non-atomic kmap */
-
- kaddr = kmap(page);
- to = kaddr + offset;
- left = copyin(to, buf, copy);
- copy -= left;
- skip += copy;
- to += copy;
- bytes -= copy;
- while (unlikely(!left && bytes)) {
- iov++;
- buf = iov->iov_base;
- copy = min(bytes, iov->iov_len);
- left = copyin(to, buf, copy);
- copy -= left;
- skip = copy;
- to += copy;
- bytes -= copy;
- }
- kunmap(page);
-
-done:
- if (skip == iov->iov_len) {
- iov++;
- skip = 0;
- }
- i->count -= wanted - bytes;
- i->nr_segs -= iov - i->iov;
- i->iov = iov;
- i->iov_offset = skip;
- return wanted - bytes;
-}
-
#ifdef PIPE_PARANOIA
static bool sanity(const struct iov_iter *i)
{
@@ -848,24 +680,14 @@ static inline bool page_copy_sane(struct page *page, size_t offset, size_t n)
static size_t __copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
struct iov_iter *i)
{
- if (likely(iter_is_iovec(i)))
- return copy_page_to_iter_iovec(page, offset, bytes, i);
- if (iov_iter_is_bvec(i) || iov_iter_is_kvec(i) || iov_iter_is_xarray(i)) {
+ if (unlikely(iov_iter_is_pipe(i))) {
+ return copy_page_to_iter_pipe(page, offset, bytes, i);
+ } else {
void *kaddr = kmap_local_page(page);
size_t wanted = _copy_to_iter(kaddr + offset, bytes, i);
kunmap_local(kaddr);
return wanted;
}
- if (iov_iter_is_pipe(i))
- return copy_page_to_iter_pipe(page, offset, bytes, i);
- if (unlikely(iov_iter_is_discard(i))) {
- if (unlikely(i->count < bytes))
- bytes = i->count;
- i->count -= bytes;
- return bytes;
- }
- WARN_ON(1);
- return 0;
}
size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
@@ -896,17 +718,12 @@ EXPORT_SYMBOL(copy_page_to_iter);
size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
struct iov_iter *i)
{
- if (unlikely(!page_copy_sane(page, offset, bytes)))
- return 0;
- if (likely(iter_is_iovec(i)))
- return copy_page_from_iter_iovec(page, offset, bytes, i);
- if (iov_iter_is_bvec(i) || iov_iter_is_kvec(i) || iov_iter_is_xarray(i)) {
+ if (page_copy_sane(page, offset, bytes)) {
void *kaddr = kmap_local_page(page);
size_t wanted = _copy_from_iter(kaddr + offset, bytes, i);
kunmap_local(kaddr);
return wanted;
}
- WARN_ON(1);
return 0;
}
EXPORT_SYMBOL(copy_page_from_iter);
--
2.30.2
