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-rw-r--r--mm/iov_iter.c254
1 files changed, 235 insertions, 19 deletions
diff --git a/mm/iov_iter.c b/mm/iov_iter.c
index ab88dc0ea1d3..eafcf60f6b83 100644
--- a/mm/iov_iter.c
+++ b/mm/iov_iter.c
@@ -4,6 +4,96 @@
#include <linux/slab.h>
#include <linux/vmalloc.h>
+static size_t copy_to_iter_iovec(void *from, size_t bytes, struct iov_iter *i)
+{
+ size_t skip, copy, left, wanted;
+ const struct iovec *iov;
+ char __user *buf;
+
+ if (unlikely(bytes > i->count))
+ bytes = i->count;
+
+ if (unlikely(!bytes))
+ return 0;
+
+ wanted = bytes;
+ iov = i->iov;
+ skip = i->iov_offset;
+ buf = iov->iov_base + skip;
+ copy = min(bytes, iov->iov_len - skip);
+
+ left = __copy_to_user(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 = __copy_to_user(buf, from, copy);
+ copy -= left;
+ skip = copy;
+ from += copy;
+ bytes -= copy;
+ }
+
+ 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_from_iter_iovec(void *to, size_t bytes, struct iov_iter *i)
+{
+ size_t skip, copy, left, wanted;
+ const struct iovec *iov;
+ char __user *buf;
+
+ if (unlikely(bytes > i->count))
+ bytes = i->count;
+
+ if (unlikely(!bytes))
+ return 0;
+
+ wanted = bytes;
+ iov = i->iov;
+ skip = i->iov_offset;
+ buf = iov->iov_base + skip;
+ copy = min(bytes, iov->iov_len - skip);
+
+ left = __copy_from_user(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 = __copy_from_user(to, buf, copy);
+ copy -= left;
+ skip = copy;
+ to += copy;
+ bytes -= copy;
+ }
+
+ 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_to_iter_iovec(struct page *page, size_t offset, size_t bytes,
struct iov_iter *i)
{
@@ -166,6 +256,50 @@ done:
return wanted - bytes;
}
+static size_t zero_iovec(size_t bytes, struct iov_iter *i)
+{
+ size_t skip, copy, left, wanted;
+ const struct iovec *iov;
+ char __user *buf;
+
+ if (unlikely(bytes > i->count))
+ bytes = i->count;
+
+ if (unlikely(!bytes))
+ return 0;
+
+ wanted = bytes;
+ iov = i->iov;
+ skip = i->iov_offset;
+ buf = iov->iov_base + skip;
+ copy = min(bytes, iov->iov_len - skip);
+
+ left = __clear_user(buf, copy);
+ copy -= left;
+ skip += copy;
+ bytes -= copy;
+
+ while (unlikely(!left && bytes)) {
+ iov++;
+ buf = iov->iov_base;
+ copy = min(bytes, iov->iov_len);
+ left = __clear_user(buf, copy);
+ copy -= left;
+ skip = copy;
+ bytes -= copy;
+ }
+
+ 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 __iovec_copy_from_user_inatomic(char *vaddr,
const struct iovec *iov, size_t base, size_t bytes)
{
@@ -310,7 +444,7 @@ void iov_iter_init(struct iov_iter *i, int direction,
EXPORT_SYMBOL(iov_iter_init);
static ssize_t get_pages_iovec(struct iov_iter *i,
- struct page **pages, unsigned maxpages,
+ struct page **pages, size_t maxsize, unsigned maxpages,
size_t *start)
{
size_t offset = i->iov_offset;
@@ -323,6 +457,8 @@ static ssize_t get_pages_iovec(struct iov_iter *i,
len = iov->iov_len - offset;
if (len > i->count)
len = i->count;
+ if (len > maxsize)
+ len = maxsize;
addr = (unsigned long)iov->iov_base + offset;
len += *start = addr & (PAGE_SIZE - 1);
if (len > maxpages * PAGE_SIZE)
@@ -412,12 +548,17 @@ static void memcpy_to_page(struct page *page, size_t offset, char *from, size_t
kunmap_atomic(to);
}
-static size_t copy_page_to_iter_bvec(struct page *page, size_t offset, size_t bytes,
- struct iov_iter *i)
+static void memzero_page(struct page *page, size_t offset, size_t len)
+{
+ char *addr = kmap_atomic(page);
+ memset(addr + offset, 0, len);
+ kunmap_atomic(addr);
+}
+
+static size_t copy_to_iter_bvec(void *from, size_t bytes, struct iov_iter *i)
{
size_t skip, copy, wanted;
const struct bio_vec *bvec;
- void *kaddr, *from;
if (unlikely(bytes > i->count))
bytes = i->count;
@@ -430,8 +571,6 @@ static size_t copy_page_to_iter_bvec(struct page *page, size_t offset, size_t by
skip = i->iov_offset;
copy = min_t(size_t, bytes, bvec->bv_len - skip);
- kaddr = kmap_atomic(page);
- from = kaddr + offset;
memcpy_to_page(bvec->bv_page, skip + bvec->bv_offset, from, copy);
skip += copy;
from += copy;
@@ -444,7 +583,6 @@ static size_t copy_page_to_iter_bvec(struct page *page, size_t offset, size_t by
from += copy;
bytes -= copy;
}
- kunmap_atomic(kaddr);
if (skip == bvec->bv_len) {
bvec++;
skip = 0;
@@ -456,12 +594,10 @@ static size_t copy_page_to_iter_bvec(struct page *page, size_t offset, size_t by
return wanted - bytes;
}
-static size_t copy_page_from_iter_bvec(struct page *page, size_t offset, size_t bytes,
- struct iov_iter *i)
+static size_t copy_from_iter_bvec(void *to, size_t bytes, struct iov_iter *i)
{
size_t skip, copy, wanted;
const struct bio_vec *bvec;
- void *kaddr, *to;
if (unlikely(bytes > i->count))
bytes = i->count;
@@ -473,10 +609,6 @@ static size_t copy_page_from_iter_bvec(struct page *page, size_t offset, size_t
bvec = i->bvec;
skip = i->iov_offset;
- kaddr = kmap_atomic(page);
-
- to = kaddr + offset;
-
copy = min(bytes, bvec->bv_len - skip);
memcpy_from_page(to, bvec->bv_page, bvec->bv_offset + skip, copy);
@@ -493,7 +625,6 @@ static size_t copy_page_from_iter_bvec(struct page *page, size_t offset, size_t
to += copy;
bytes -= copy;
}
- kunmap_atomic(kaddr);
if (skip == bvec->bv_len) {
bvec++;
skip = 0;
@@ -505,6 +636,61 @@ static size_t copy_page_from_iter_bvec(struct page *page, size_t offset, size_t
return wanted;
}
+static size_t copy_page_to_iter_bvec(struct page *page, size_t offset,
+ size_t bytes, struct iov_iter *i)
+{
+ void *kaddr = kmap_atomic(page);
+ size_t wanted = copy_to_iter_bvec(kaddr + offset, bytes, i);
+ kunmap_atomic(kaddr);
+ return wanted;
+}
+
+static size_t copy_page_from_iter_bvec(struct page *page, size_t offset,
+ size_t bytes, struct iov_iter *i)
+{
+ void *kaddr = kmap_atomic(page);
+ size_t wanted = copy_from_iter_bvec(kaddr + offset, bytes, i);
+ kunmap_atomic(kaddr);
+ return wanted;
+}
+
+static size_t zero_bvec(size_t bytes, struct iov_iter *i)
+{
+ size_t skip, copy, wanted;
+ const struct bio_vec *bvec;
+
+ if (unlikely(bytes > i->count))
+ bytes = i->count;
+
+ if (unlikely(!bytes))
+ return 0;
+
+ wanted = bytes;
+ bvec = i->bvec;
+ skip = i->iov_offset;
+ copy = min_t(size_t, bytes, bvec->bv_len - skip);
+
+ memzero_page(bvec->bv_page, skip + bvec->bv_offset, copy);
+ skip += copy;
+ bytes -= copy;
+ while (bytes) {
+ bvec++;
+ copy = min(bytes, (size_t)bvec->bv_len);
+ memzero_page(bvec->bv_page, bvec->bv_offset, copy);
+ skip = copy;
+ bytes -= copy;
+ }
+ if (skip == bvec->bv_len) {
+ bvec++;
+ skip = 0;
+ }
+ i->count -= wanted - bytes;
+ i->nr_segs -= bvec - i->bvec;
+ i->bvec = bvec;
+ i->iov_offset = skip;
+ return wanted - bytes;
+}
+
static size_t copy_from_user_bvec(struct page *page,
struct iov_iter *i, unsigned long offset, size_t bytes)
{
@@ -588,13 +774,15 @@ static unsigned long alignment_bvec(const struct iov_iter *i)
}
static ssize_t get_pages_bvec(struct iov_iter *i,
- struct page **pages, unsigned maxpages,
+ struct page **pages, size_t maxsize, unsigned maxpages,
size_t *start)
{
const struct bio_vec *bvec = i->bvec;
size_t len = bvec->bv_len - i->iov_offset;
if (len > i->count)
len = i->count;
+ if (len > maxsize)
+ len = maxsize;
/* can't be more than PAGE_SIZE */
*start = bvec->bv_offset + i->iov_offset;
@@ -668,6 +856,34 @@ size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
}
EXPORT_SYMBOL(copy_page_from_iter);
+size_t copy_to_iter(void *addr, size_t bytes, struct iov_iter *i)
+{
+ if (i->type & ITER_BVEC)
+ return copy_to_iter_bvec(addr, bytes, i);
+ else
+ return copy_to_iter_iovec(addr, bytes, i);
+}
+EXPORT_SYMBOL(copy_to_iter);
+
+size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
+{
+ if (i->type & ITER_BVEC)
+ return copy_from_iter_bvec(addr, bytes, i);
+ else
+ return copy_from_iter_iovec(addr, bytes, i);
+}
+EXPORT_SYMBOL(copy_from_iter);
+
+size_t iov_iter_zero(size_t bytes, struct iov_iter *i)
+{
+ if (i->type & ITER_BVEC) {
+ return zero_bvec(bytes, i);
+ } else {
+ return zero_iovec(bytes, i);
+ }
+}
+EXPORT_SYMBOL(iov_iter_zero);
+
size_t iov_iter_copy_from_user_atomic(struct page *page,
struct iov_iter *i, unsigned long offset, size_t bytes)
{
@@ -711,13 +927,13 @@ unsigned long iov_iter_alignment(const struct iov_iter *i)
EXPORT_SYMBOL(iov_iter_alignment);
ssize_t iov_iter_get_pages(struct iov_iter *i,
- struct page **pages, unsigned maxpages,
+ struct page **pages, size_t maxsize, unsigned maxpages,
size_t *start)
{
if (i->type & ITER_BVEC)
- return get_pages_bvec(i, pages, maxpages, start);
+ return get_pages_bvec(i, pages, maxsize, maxpages, start);
else
- return get_pages_iovec(i, pages, maxpages, start);
+ return get_pages_iovec(i, pages, maxsize, maxpages, start);
}
EXPORT_SYMBOL(iov_iter_get_pages);
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.