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alistair23-linux/lib/iov_iter.c
Vegard Nossum ffecee4f24 iov_iter: kernel-doc import_iovec() and rw_copy_check_uvector() 
Both import_iovec() and rw_copy_check_uvector() take an array
(typically small and on-stack) which is used to hold an iovec array copy
from userspace. This is to avoid an expensive memory allocation in the
fast path (i.e. few iovec elements).

The caller may have to check whether these functions actually used
the provided buffer or allocated a new one -- but this differs between
the too. Let's just add a kernel doc to clarify what the semantics are
for each function.

Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-10-14 20:00:34 -04:00

1221 lines
28 KiB
C
Raw Blame History

#include <linux/export.h>
#include <linux/uio.h>
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/splice.h>
#include <net/checksum.h>
#define PIPE_PARANOIA /* for now */
#define iterate_iovec(i, n, __v, __p, skip, STEP) { \
size_t left; \
size_t wanted = n; \
__p = i->iov; \
__v.iov_len = min(n, __p->iov_len - skip); \
if (likely(__v.iov_len)) { \
__v.iov_base = __p->iov_base + skip; \
left = (STEP); \
__v.iov_len -= left; \
skip += __v.iov_len; \
n -= __v.iov_len; \
} else { \
left = 0; \
} \
while (unlikely(!left && n)) { \
__p++; \
__v.iov_len = min(n, __p->iov_len); \
if (unlikely(!__v.iov_len)) \
continue; \
__v.iov_base = __p->iov_base; \
left = (STEP); \
__v.iov_len -= left; \
skip = __v.iov_len; \
n -= __v.iov_len; \
} \
n = wanted - n; \
}
#define iterate_kvec(i, n, __v, __p, skip, STEP) { \
size_t wanted = n; \
__p = i->kvec; \
__v.iov_len = min(n, __p->iov_len - skip); \
if (likely(__v.iov_len)) { \
__v.iov_base = __p->iov_base + skip; \
(void)(STEP); \
skip += __v.iov_len; \
n -= __v.iov_len; \
} \
while (unlikely(n)) { \
__p++; \
__v.iov_len = min(n, __p->iov_len); \
if (unlikely(!__v.iov_len)) \
continue; \
__v.iov_base = __p->iov_base; \
(void)(STEP); \
skip = __v.iov_len; \
n -= __v.iov_len; \
} \
n = wanted; \
}
#define iterate_bvec(i, n, __v, __bi, skip, STEP) { \
struct bvec_iter __start; \
__start.bi_size = n; \
__start.bi_bvec_done = skip; \
__start.bi_idx = 0; \
for_each_bvec(__v, i->bvec, __bi, __start) { \
if (!__v.bv_len) \
continue; \
(void)(STEP); \
} \
}
#define iterate_all_kinds(i, n, v, I, B, K) { \
size_t skip = i->iov_offset; \
if (unlikely(i->type & ITER_BVEC)) { \
struct bio_vec v; \
struct bvec_iter __bi; \
iterate_bvec(i, n, v, __bi, skip, (B)) \
} else if (unlikely(i->type & ITER_KVEC)) { \
const struct kvec *kvec; \
struct kvec v; \
iterate_kvec(i, n, v, kvec, skip, (K)) \
} else { \
const struct iovec *iov; \
struct iovec v; \
iterate_iovec(i, n, v, iov, skip, (I)) \
} \
}
#define iterate_and_advance(i, n, v, I, B, K) { \
if (unlikely(i->count < n)) \
n = i->count; \
if (i->count) { \
size_t skip = i->iov_offset; \
if (unlikely(i->type & ITER_BVEC)) { \
const struct bio_vec *bvec = i->bvec; \
struct bio_vec v; \
struct bvec_iter __bi; \
iterate_bvec(i, n, v, __bi, skip, (B)) \
i->bvec = __bvec_iter_bvec(i->bvec, __bi); \
i->nr_segs -= i->bvec - bvec; \
skip = __bi.bi_bvec_done; \
} else if (unlikely(i->type & ITER_KVEC)) { \
const struct kvec *kvec; \
struct kvec v; \
iterate_kvec(i, n, v, kvec, skip, (K)) \
if (skip == kvec->iov_len) { \
kvec++; \
skip = 0; \
} \
i->nr_segs -= kvec - i->kvec; \
i->kvec = kvec; \
} else { \
const struct iovec *iov; \
struct iovec v; \
iterate_iovec(i, n, v, iov, skip, (I)) \
if (skip == iov->iov_len) { \
iov++; \
skip = 0; \
} \
i->nr_segs -= iov - i->iov; \
i->iov = iov; \
} \
i->count -= n; \
i->iov_offset = skip; \
} \
}
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;
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_pages_writeable(buf, copy)) {
kaddr = kmap_atomic(page);
from = kaddr + offset;
/* first chunk, usually the only one */
left = __copy_to_user_inatomic(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_inatomic(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 = __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;
}
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;
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_pages_readable(buf, copy)) {
kaddr = kmap_atomic(page);
to = kaddr + offset;
/* first chunk, usually the only one */
left = __copy_from_user_inatomic(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_inatomic(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 = __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;
}
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)
{
struct pipe_inode_info *pipe = i->pipe;
int idx = i->idx;
int next = pipe->curbuf + pipe->nrbufs;
if (i->iov_offset) {
struct pipe_buffer *p;
if (unlikely(!pipe->nrbufs))
goto Bad; // pipe must be non-empty
if (unlikely(idx != ((next - 1) & (pipe->buffers - 1))))
goto Bad; // must be at the last buffer...
p = &pipe->bufs[idx];
if (unlikely(p->offset + p->len != i->iov_offset))
goto Bad; // ... at the end of segment
} else {
if (idx != (next & (pipe->buffers - 1)))
goto Bad; // must be right after the last buffer
}
return true;
Bad:
printk(KERN_ERR "idx = %d, offset = %zd\n", i->idx, i->iov_offset);
printk(KERN_ERR "curbuf = %d, nrbufs = %d, buffers = %d\n",
pipe->curbuf, pipe->nrbufs, pipe->buffers);
for (idx = 0; idx < pipe->buffers; idx++)
printk(KERN_ERR "[%p %p %d %d]\n",
pipe->bufs[idx].ops,
pipe->bufs[idx].page,
pipe->bufs[idx].offset,
pipe->bufs[idx].len);
WARN_ON(1);
return false;
}
#else
#define sanity(i) true
#endif
static inline int next_idx(int idx, struct pipe_inode_info *pipe)
{
return (idx + 1) & (pipe->buffers - 1);
}
static size_t copy_page_to_iter_pipe(struct page *page, size_t offset, size_t bytes,
struct iov_iter *i)
{
struct pipe_inode_info *pipe = i->pipe;
struct pipe_buffer *buf;
size_t off;
int idx;
if (unlikely(bytes > i->count))
bytes = i->count;
if (unlikely(!bytes))
return 0;
if (!sanity(i))
return 0;
off = i->iov_offset;
idx = i->idx;
buf = &pipe->bufs[idx];
if (off) {
if (offset == off && buf->page == page) {
/* merge with the last one */
buf->len += bytes;
i->iov_offset += bytes;
goto out;
}
idx = next_idx(idx, pipe);
buf = &pipe->bufs[idx];
}
if (idx == pipe->curbuf && pipe->nrbufs)
return 0;
pipe->nrbufs++;
buf->ops = &page_cache_pipe_buf_ops;
get_page(buf->page = page);
buf->offset = offset;
buf->len = bytes;
i->iov_offset = offset + bytes;
i->idx = idx;
out:
i->count -= bytes;
return bytes;
}
/*
* Fault in one or more iovecs of the given iov_iter, to a maximum length of
* bytes. For each iovec, fault in each page that constitutes the iovec.
*
* Return 0 on success, or non-zero if the memory could not be accessed (i.e.
* because it is an invalid address).
*/
int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
{
size_t skip = i->iov_offset;
const struct iovec *iov;
int err;
struct iovec v;
if (!(i->type & (ITER_BVEC|ITER_KVEC))) {
iterate_iovec(i, bytes, v, iov, skip, ({
err = fault_in_pages_readable(v.iov_base, v.iov_len);
if (unlikely(err))
return err;
0;}))
}
return 0;
}
EXPORT_SYMBOL(iov_iter_fault_in_readable);
void iov_iter_init(struct iov_iter *i, int direction,
const struct iovec *iov, unsigned long nr_segs,
size_t count)
{
/* It will get better. Eventually... */
if (segment_eq(get_fs(), KERNEL_DS)) {
direction |= ITER_KVEC;
i->type = direction;
i->kvec = (struct kvec *)iov;
} else {
i->type = direction;
i->iov = iov;
}
i->nr_segs = nr_segs;
i->iov_offset = 0;
i->count = count;
}
EXPORT_SYMBOL(iov_iter_init);
static void memcpy_from_page(char *to, struct page *page, size_t offset, size_t len)
{
char *from = kmap_atomic(page);
memcpy(to, from + offset, len);
kunmap_atomic(from);
}
static void memcpy_to_page(struct page *page, size_t offset, const char *from, size_t len)
{
char *to = kmap_atomic(page);
memcpy(to + offset, from, len);
kunmap_atomic(to);
}
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 inline bool allocated(struct pipe_buffer *buf)
{
return buf->ops == &default_pipe_buf_ops;
}
static inline void data_start(const struct iov_iter *i, int *idxp, size_t *offp)
{
size_t off = i->iov_offset;
int idx = i->idx;
if (off && (!allocated(&i->pipe->bufs[idx]) || off == PAGE_SIZE)) {
idx = next_idx(idx, i->pipe);
off = 0;
}
*idxp = idx;
*offp = off;
}
static size_t push_pipe(struct iov_iter *i, size_t size,
int *idxp, size_t *offp)
{
struct pipe_inode_info *pipe = i->pipe;
size_t off;
int idx;
ssize_t left;
if (unlikely(size > i->count))
size = i->count;
if (unlikely(!size))
return 0;
left = size;
data_start(i, &idx, &off);
*idxp = idx;
*offp = off;
if (off) {
left -= PAGE_SIZE - off;
if (left <= 0) {
pipe->bufs[idx].len += size;
return size;
}
pipe->bufs[idx].len = PAGE_SIZE;
idx = next_idx(idx, pipe);
}
while (idx != pipe->curbuf || !pipe->nrbufs) {
struct page *page = alloc_page(GFP_USER);
if (!page)
break;
pipe->nrbufs++;
pipe->bufs[idx].ops = &default_pipe_buf_ops;
pipe->bufs[idx].page = page;
pipe->bufs[idx].offset = 0;
if (left <= PAGE_SIZE) {
pipe->bufs[idx].len = left;
return size;
}
pipe->bufs[idx].len = PAGE_SIZE;
left -= PAGE_SIZE;
idx = next_idx(idx, pipe);
}
return size - left;
}
static size_t copy_pipe_to_iter(const void *addr, size_t bytes,
struct iov_iter *i)
{
struct pipe_inode_info *pipe = i->pipe;
size_t n, off;
int idx;
if (!sanity(i))
return 0;
bytes = n = push_pipe(i, bytes, &idx, &off);
if (unlikely(!n))
return 0;
for ( ; n; idx = next_idx(idx, pipe), off = 0) {
size_t chunk = min_t(size_t, n, PAGE_SIZE - off);
memcpy_to_page(pipe->bufs[idx].page, off, addr, chunk);
i->idx = idx;
i->iov_offset = off + chunk;
n -= chunk;
addr += chunk;
}
i->count -= bytes;
return bytes;
}
size_t copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
{
const char *from = addr;
if (unlikely(i->type & ITER_PIPE))
return copy_pipe_to_iter(addr, bytes, i);
iterate_and_advance(i, bytes, v,
__copy_to_user(v.iov_base, (from += v.iov_len) - v.iov_len,
v.iov_len),
memcpy_to_page(v.bv_page, v.bv_offset,
(from += v.bv_len) - v.bv_len, v.bv_len),
memcpy(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len)
)
return bytes;
}
EXPORT_SYMBOL(copy_to_iter);
size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
{
char *to = addr;
if (unlikely(i->type & ITER_PIPE)) {
WARN_ON(1);
return 0;
}
iterate_and_advance(i, bytes, v,
__copy_from_user((to += v.iov_len) - v.iov_len, v.iov_base,
v.iov_len),
memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
v.bv_offset, v.bv_len),
memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
)
return bytes;
}
EXPORT_SYMBOL(copy_from_iter);
size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
{
char *to = addr;
if (unlikely(i->type & ITER_PIPE)) {
WARN_ON(1);
return 0;
}
iterate_and_advance(i, bytes, v,
__copy_from_user_nocache((to += v.iov_len) - v.iov_len,
v.iov_base, v.iov_len),
memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
v.bv_offset, v.bv_len),
memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
)
return bytes;
}
EXPORT_SYMBOL(copy_from_iter_nocache);
size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
struct iov_iter *i)
{
if (i->type & (ITER_BVEC|ITER_KVEC)) {
void *kaddr = kmap_atomic(page);
size_t wanted = copy_to_iter(kaddr + offset, bytes, i);
kunmap_atomic(kaddr);
return wanted;
} else if (likely(!(i->type & ITER_PIPE)))
return copy_page_to_iter_iovec(page, offset, bytes, i);
else
return copy_page_to_iter_pipe(page, offset, bytes, i);
}
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(i->type & ITER_PIPE)) {
WARN_ON(1);
return 0;
}
if (i->type & (ITER_BVEC|ITER_KVEC)) {
void *kaddr = kmap_atomic(page);
size_t wanted = copy_from_iter(kaddr + offset, bytes, i);
kunmap_atomic(kaddr);
return wanted;
} else
return copy_page_from_iter_iovec(page, offset, bytes, i);
}
EXPORT_SYMBOL(copy_page_from_iter);
static size_t pipe_zero(size_t bytes, struct iov_iter *i)
{
struct pipe_inode_info *pipe = i->pipe;
size_t n, off;
int idx;
if (!sanity(i))
return 0;
bytes = n = push_pipe(i, bytes, &idx, &off);
if (unlikely(!n))
return 0;
for ( ; n; idx = next_idx(idx, pipe), off = 0) {
size_t chunk = min_t(size_t, n, PAGE_SIZE - off);
memzero_page(pipe->bufs[idx].page, off, chunk);
i->idx = idx;
i->iov_offset = off + chunk;
n -= chunk;
}
i->count -= bytes;
return bytes;
}
size_t iov_iter_zero(size_t bytes, struct iov_iter *i)
{
if (unlikely(i->type & ITER_PIPE))
return pipe_zero(bytes, i);
iterate_and_advance(i, bytes, v,
__clear_user(v.iov_base, v.iov_len),
memzero_page(v.bv_page, v.bv_offset, v.bv_len),
memset(v.iov_base, 0, v.iov_len)
)
return bytes;
}
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)
{
char *kaddr = kmap_atomic(page), *p = kaddr + offset;
if (unlikely(i->type & ITER_PIPE)) {
kunmap_atomic(kaddr);
WARN_ON(1);
return 0;
}
iterate_all_kinds(i, bytes, v,
__copy_from_user_inatomic((p += v.iov_len) - v.iov_len,
v.iov_base, v.iov_len),
memcpy_from_page((p += v.bv_len) - v.bv_len, v.bv_page,
v.bv_offset, v.bv_len),
memcpy((p += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
)
kunmap_atomic(kaddr);
return bytes;
}
EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
static void pipe_advance(struct iov_iter *i, size_t size)
{
struct pipe_inode_info *pipe = i->pipe;
struct pipe_buffer *buf;
int idx = i->idx;
size_t off = i->iov_offset;
if (unlikely(i->count < size))
size = i->count;
if (size) {
if (off) /* make it relative to the beginning of buffer */
size += off - pipe->bufs[idx].offset;
while (1) {
buf = &pipe->bufs[idx];
if (size <= buf->len)
break;
size -= buf->len;
idx = next_idx(idx, pipe);
}
buf->len = size;
i->idx = idx;
off = i->iov_offset = buf->offset + size;
}
if (off)
idx = next_idx(idx, pipe);
if (pipe->nrbufs) {
int unused = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1);
/* [curbuf,unused) is in use. Free [idx,unused) */
while (idx != unused) {
pipe_buf_release(pipe, &pipe->bufs[idx]);
idx = next_idx(idx, pipe);
pipe->nrbufs--;
}
}
}
void iov_iter_advance(struct iov_iter *i, size_t size)
{
if (unlikely(i->type & ITER_PIPE)) {
pipe_advance(i, size);
return;
}
iterate_and_advance(i, size, v, 0, 0, 0)
}
EXPORT_SYMBOL(iov_iter_advance);
/*
* Return the count of just the current iov_iter segment.
*/
size_t iov_iter_single_seg_count(const struct iov_iter *i)
{
if (unlikely(i->type & ITER_PIPE))
return i->count; // it is a silly place, anyway
if (i->nr_segs == 1)
return i->count;
else if (i->type & ITER_BVEC)
return min(i->count, i->bvec->bv_len - i->iov_offset);
else
return min(i->count, i->iov->iov_len - i->iov_offset);
}
EXPORT_SYMBOL(iov_iter_single_seg_count);
void iov_iter_kvec(struct iov_iter *i, int direction,
const struct kvec *kvec, unsigned long nr_segs,
size_t count)
{
BUG_ON(!(direction & ITER_KVEC));
i->type = direction;
i->kvec = kvec;
i->nr_segs = nr_segs;
i->iov_offset = 0;
i->count = count;
}
EXPORT_SYMBOL(iov_iter_kvec);
void iov_iter_bvec(struct iov_iter *i, int direction,
const struct bio_vec *bvec, unsigned long nr_segs,
size_t count)
{
BUG_ON(!(direction & ITER_BVEC));
i->type = direction;
i->bvec = bvec;
i->nr_segs = nr_segs;
i->iov_offset = 0;
i->count = count;
}
EXPORT_SYMBOL(iov_iter_bvec);
void iov_iter_pipe(struct iov_iter *i, int direction,
struct pipe_inode_info *pipe,
size_t count)
{
BUG_ON(direction != ITER_PIPE);
i->type = direction;
i->pipe = pipe;
i->idx = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1);
i->iov_offset = 0;
i->count = count;
}
EXPORT_SYMBOL(iov_iter_pipe);
unsigned long iov_iter_alignment(const struct iov_iter *i)
{
unsigned long res = 0;
size_t size = i->count;
if (!size)
return 0;
if (unlikely(i->type & ITER_PIPE)) {
if (i->iov_offset && allocated(&i->pipe->bufs[i->idx]))
return size | i->iov_offset;
return size;
}
iterate_all_kinds(i, size, v,
(res |= (unsigned long)v.iov_base | v.iov_len, 0),
res |= v.bv_offset | v.bv_len,
res |= (unsigned long)v.iov_base | v.iov_len
)
return res;
}
EXPORT_SYMBOL(iov_iter_alignment);
unsigned long iov_iter_gap_alignment(const struct iov_iter *i)
{
unsigned long res = 0;
size_t size = i->count;
if (!size)
return 0;
if (unlikely(i->type & ITER_PIPE)) {
WARN_ON(1);
return ~0U;
}
iterate_all_kinds(i, size, v,
(res |= (!res ? 0 : (unsigned long)v.iov_base) |
(size != v.iov_len ? size : 0), 0),
(res |= (!res ? 0 : (unsigned long)v.bv_offset) |
(size != v.bv_len ? size : 0)),
(res |= (!res ? 0 : (unsigned long)v.iov_base) |
(size != v.iov_len ? size : 0))
);
return res;
}
EXPORT_SYMBOL(iov_iter_gap_alignment);
static inline size_t __pipe_get_pages(struct iov_iter *i,
size_t maxsize,
struct page **pages,
int idx,
size_t *start)
{
struct pipe_inode_info *pipe = i->pipe;
ssize_t n = push_pipe(i, maxsize, &idx, start);
if (!n)
return -EFAULT;
maxsize = n;
n += *start;
while (n > 0) {
get_page(*pages++ = pipe->bufs[idx].page);
idx = next_idx(idx, pipe);
n -= PAGE_SIZE;
}
return maxsize;
}
static ssize_t pipe_get_pages(struct iov_iter *i,
struct page **pages, size_t maxsize, unsigned maxpages,
size_t *start)
{
unsigned npages;
size_t capacity;
int idx;
if (!sanity(i))
return -EFAULT;
data_start(i, &idx, start);
/* some of this one + all after this one */
npages = ((i->pipe->curbuf - idx - 1) & (i->pipe->buffers - 1)) + 1;
capacity = min(npages,maxpages) * PAGE_SIZE - *start;
return __pipe_get_pages(i, min(maxsize, capacity), pages, idx, start);
}
ssize_t iov_iter_get_pages(struct iov_iter *i,
struct page **pages, size_t maxsize, unsigned maxpages,
size_t *start)
{
if (maxsize > i->count)
maxsize = i->count;
if (!maxsize)
return 0;
if (unlikely(i->type & ITER_PIPE))
return pipe_get_pages(i, pages, maxsize, maxpages, start);
iterate_all_kinds(i, maxsize, v, ({
unsigned long addr = (unsigned long)v.iov_base;
size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1));
int n;
int res;
if (len > maxpages * PAGE_SIZE)
len = maxpages * PAGE_SIZE;
addr &= ~(PAGE_SIZE - 1);
n = DIV_ROUND_UP(len, PAGE_SIZE);
res = get_user_pages_fast(addr, n, (i->type & WRITE) != WRITE, pages);
if (unlikely(res < 0))
return res;
return (res == n ? len : res * PAGE_SIZE) - *start;
0;}),({
/* can't be more than PAGE_SIZE */
*start = v.bv_offset;
get_page(*pages = v.bv_page);
return v.bv_len;
}),({
return -EFAULT;
})
)
return 0;
}
EXPORT_SYMBOL(iov_iter_get_pages);
static struct page **get_pages_array(size_t n)
{
struct page **p = kmalloc(n * sizeof(struct page *), GFP_KERNEL);
if (!p)
p = vmalloc(n * sizeof(struct page *));
return p;
}
static ssize_t pipe_get_pages_alloc(struct iov_iter *i,
struct page ***pages, size_t maxsize,
size_t *start)
{
struct page **p;
size_t n;
int idx;
int npages;
if (!sanity(i))
return -EFAULT;
data_start(i, &idx, start);
/* some of this one + all after this one */
npages = ((i->pipe->curbuf - idx - 1) & (i->pipe->buffers - 1)) + 1;
n = npages * PAGE_SIZE - *start;
if (maxsize > n)
maxsize = n;
else
npages = DIV_ROUND_UP(maxsize + *start, PAGE_SIZE);
p = get_pages_array(npages);
if (!p)
return -ENOMEM;
n = __pipe_get_pages(i, maxsize, p, idx, start);
if (n > 0)
*pages = p;
else
kvfree(p);
return n;
}
ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
struct page ***pages, size_t maxsize,
size_t *start)
{
struct page **p;
if (maxsize > i->count)
maxsize = i->count;
if (!maxsize)
return 0;
if (unlikely(i->type & ITER_PIPE))
return pipe_get_pages_alloc(i, pages, maxsize, start);
iterate_all_kinds(i, maxsize, v, ({
unsigned long addr = (unsigned long)v.iov_base;
size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1));
int n;
int res;
addr &= ~(PAGE_SIZE - 1);
n = DIV_ROUND_UP(len, PAGE_SIZE);
p = get_pages_array(n);
if (!p)
return -ENOMEM;
res = get_user_pages_fast(addr, n, (i->type & WRITE) != WRITE, p);
if (unlikely(res < 0)) {
kvfree(p);
return res;
}
*pages = p;
return (res == n ? len : res * PAGE_SIZE) - *start;
0;}),({
/* can't be more than PAGE_SIZE */
*start = v.bv_offset;
*pages = p = get_pages_array(1);
if (!p)
return -ENOMEM;
get_page(*p = v.bv_page);
return v.bv_len;
}),({
return -EFAULT;
})
)
return 0;
}
EXPORT_SYMBOL(iov_iter_get_pages_alloc);
size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum,
struct iov_iter *i)
{
char *to = addr;
__wsum sum, next;
size_t off = 0;
sum = *csum;
if (unlikely(i->type & ITER_PIPE)) {
WARN_ON(1);
return 0;
}
iterate_and_advance(i, bytes, v, ({
int err = 0;
next = csum_and_copy_from_user(v.iov_base,
(to += v.iov_len) - v.iov_len,
v.iov_len, 0, &err);
if (!err) {
sum = csum_block_add(sum, next, off);
off += v.iov_len;
}
err ? v.iov_len : 0;
}), ({
char *p = kmap_atomic(v.bv_page);
next = csum_partial_copy_nocheck(p + v.bv_offset,
(to += v.bv_len) - v.bv_len,
v.bv_len, 0);
kunmap_atomic(p);
sum = csum_block_add(sum, next, off);
off += v.bv_len;
}),({
next = csum_partial_copy_nocheck(v.iov_base,
(to += v.iov_len) - v.iov_len,
v.iov_len, 0);
sum = csum_block_add(sum, next, off);
off += v.iov_len;
})
)
*csum = sum;
return bytes;
}
EXPORT_SYMBOL(csum_and_copy_from_iter);
size_t csum_and_copy_to_iter(const void *addr, size_t bytes, __wsum *csum,
struct iov_iter *i)
{
const char *from = addr;
__wsum sum, next;
size_t off = 0;
sum = *csum;
if (unlikely(i->type & ITER_PIPE)) {
WARN_ON(1); /* for now */
return 0;
}
iterate_and_advance(i, bytes, v, ({
int err = 0;
next = csum_and_copy_to_user((from += v.iov_len) - v.iov_len,
v.iov_base,
v.iov_len, 0, &err);
if (!err) {
sum = csum_block_add(sum, next, off);
off += v.iov_len;
}
err ? v.iov_len : 0;
}), ({
char *p = kmap_atomic(v.bv_page);
next = csum_partial_copy_nocheck((from += v.bv_len) - v.bv_len,
p + v.bv_offset,
v.bv_len, 0);
kunmap_atomic(p);
sum = csum_block_add(sum, next, off);
off += v.bv_len;
}),({
next = csum_partial_copy_nocheck((from += v.iov_len) - v.iov_len,
v.iov_base,
v.iov_len, 0);
sum = csum_block_add(sum, next, off);
off += v.iov_len;
})
)
*csum = sum;
return bytes;
}
EXPORT_SYMBOL(csum_and_copy_to_iter);
int iov_iter_npages(const struct iov_iter *i, int maxpages)
{
size_t size = i->count;
int npages = 0;
if (!size)
return 0;
if (unlikely(i->type & ITER_PIPE)) {
struct pipe_inode_info *pipe = i->pipe;
size_t off;
int idx;
if (!sanity(i))
return 0;
data_start(i, &idx, &off);
/* some of this one + all after this one */
npages = ((pipe->curbuf - idx - 1) & (pipe->buffers - 1)) + 1;
if (npages >= maxpages)
return maxpages;
} else iterate_all_kinds(i, size, v, ({
unsigned long p = (unsigned long)v.iov_base;
npages += DIV_ROUND_UP(p + v.iov_len, PAGE_SIZE)
- p / PAGE_SIZE;
if (npages >= maxpages)
return maxpages;
0;}),({
npages++;
if (npages >= maxpages)
return maxpages;
}),({
unsigned long p = (unsigned long)v.iov_base;
npages += DIV_ROUND_UP(p + v.iov_len, PAGE_SIZE)
- p / PAGE_SIZE;
if (npages >= maxpages)
return maxpages;
})
)
return npages;
}
EXPORT_SYMBOL(iov_iter_npages);
const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags)
{
*new = *old;
if (unlikely(new->type & ITER_PIPE)) {
WARN_ON(1);
return NULL;
}
if (new->type & ITER_BVEC)
return new->bvec = kmemdup(new->bvec,
new->nr_segs * sizeof(struct bio_vec),
flags);
else
/* iovec and kvec have identical layout */
return new->iov = kmemdup(new->iov,
new->nr_segs * sizeof(struct iovec),
flags);
}
EXPORT_SYMBOL(dup_iter);
/**
* import_iovec() - Copy an array of &struct iovec from userspace
* into the kernel, check that it is valid, and initialize a new
* &struct iov_iter iterator to access it.
*
* @type: One of %READ or %WRITE.
* @uvector: Pointer to the userspace array.
* @nr_segs: Number of elements in userspace array.
* @fast_segs: Number of elements in @iov.
* @iov: (input and output parameter) Pointer to pointer to (usually small
* on-stack) kernel array.
* @i: Pointer to iterator that will be initialized on success.
*
* If the array pointed to by *@iov is large enough to hold all @nr_segs,
* then this function places %NULL in *@iov on return. Otherwise, a new
* array will be allocated and the result placed in *@iov. This means that
* the caller may call kfree() on *@iov regardless of whether the small
* on-stack array was used or not (and regardless of whether this function
* returns an error or not).
*
* Return: 0 on success or negative error code on error.
*/
int import_iovec(int type, const struct iovec __user * uvector,
unsigned nr_segs, unsigned fast_segs,
struct iovec **iov, struct iov_iter *i)
{
ssize_t n;
struct iovec *p;
n = rw_copy_check_uvector(type, uvector, nr_segs, fast_segs,
*iov, &p);
if (n < 0) {
if (p != *iov)
kfree(p);
*iov = NULL;
return n;
}
iov_iter_init(i, type, p, nr_segs, n);
*iov = p == *iov ? NULL : p;
return 0;
}
EXPORT_SYMBOL(import_iovec);
#ifdef CONFIG_COMPAT
#include <linux/compat.h>
int compat_import_iovec(int type, const struct compat_iovec __user * uvector,
unsigned nr_segs, unsigned fast_segs,
struct iovec **iov, struct iov_iter *i)
{
ssize_t n;
struct iovec *p;
n = compat_rw_copy_check_uvector(type, uvector, nr_segs, fast_segs,
*iov, &p);
if (n < 0) {
if (p != *iov)
kfree(p);
*iov = NULL;
return n;
}
iov_iter_init(i, type, p, nr_segs, n);
*iov = p == *iov ? NULL : p;
return 0;
}
#endif
int import_single_range(int rw, void __user *buf, size_t len,
struct iovec *iov, struct iov_iter *i)
{
if (len > MAX_RW_COUNT)
len = MAX_RW_COUNT;
if (unlikely(!access_ok(!rw, buf, len)))
return -EFAULT;
iov->iov_base = buf;
iov->iov_len = len;
iov_iter_init(i, rw, iov, 1, len);
return 0;
}
EXPORT_SYMBOL(import_single_range);
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