linux/lib/iov_iter.c

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#include <linux/export.h>
#include <linux/bvec.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) { \
if (likely(n)) { \
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 int copyout(void __user *to, const void *from, size_t n)
{
if (access_ok(VERIFY_WRITE, to, n)) {
kasan_check_read(from, n);
n = raw_copy_to_user(to, from, n);
}
return n;
}
static int copyin(void *to, const void __user *from, size_t n)
{
if (access_ok(VERIFY_READ, from, n)) {
kasan_check_write(to, n);
n = raw_copy_from_user(to, from, 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_pages_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_pages_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)
{
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 (uaccess_kernel()) {
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);
if (iter_is_iovec(i))
might_fault();
iterate_and_advance(i, bytes, v,
copyout(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;
}
if (iter_is_iovec(i))
might_fault();
iterate_and_advance(i, bytes, v,
copyin((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);
bool _copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i)
{
char *to = addr;
if (unlikely(i->type & ITER_PIPE)) {
WARN_ON(1);
return false;
}
if (unlikely(i->count < bytes))
return false;
if (iter_is_iovec(i))
might_fault();
iterate_all_kinds(i, bytes, v, ({
if (copyin((to += v.iov_len) - v.iov_len,
v.iov_base, v.iov_len))
return false;
0;}),
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)
)
iov_iter_advance(i, bytes);
return true;
}
EXPORT_SYMBOL(_copy_from_iter_full);
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_inatomic_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);
x86, uaccess: introduce copy_from_iter_flushcache for pmem / cache-bypass operations The pmem driver has a need to transfer data with a persistent memory destination and be able to rely on the fact that the destination writes are not cached. It is sufficient for the writes to be flushed to a cpu-store-buffer (non-temporal / "movnt" in x86 terms), as we expect userspace to call fsync() to ensure data-writes have reached a power-fail-safe zone in the platform. The fsync() triggers a REQ_FUA or REQ_FLUSH to the pmem driver which will turn around and fence previous writes with an "sfence". Implement a __copy_from_user_inatomic_flushcache, memcpy_page_flushcache, and memcpy_flushcache, that guarantee that the destination buffer is not dirty in the cpu cache on completion. The new copy_from_iter_flushcache and sub-routines will be used to replace the "pmem api" (include/linux/pmem.h + arch/x86/include/asm/pmem.h). The availability of copy_from_iter_flushcache() and memcpy_flushcache() are gated by the CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE config symbol, and fallback to copy_from_iter_nocache() and plain memcpy() otherwise. This is meant to satisfy the concern from Linus that if a driver wants to do something beyond the normal nocache semantics it should be something private to that driver [1], and Al's concern that anything uaccess related belongs with the rest of the uaccess code [2]. The first consumer of this interface is a new 'copy_from_iter' dax operation so that pmem can inject cache maintenance operations without imposing this overhead on other dax-capable drivers. [1]: https://lists.01.org/pipermail/linux-nvdimm/2017-January/008364.html [2]: https://lists.01.org/pipermail/linux-nvdimm/2017-April/009942.html Cc: <x86@kernel.org> Cc: Jan Kara <jack@suse.cz> Cc: Jeff Moyer <jmoyer@redhat.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Toshi Kani <toshi.kani@hpe.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Matthew Wilcox <mawilcox@microsoft.com> Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-05-29 21:22:50 +02:00
#ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
Merge branch 'uaccess-work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull iov_iter hardening from Al Viro: "This is the iov_iter/uaccess/hardening pile. For one thing, it trims the inline part of copy_to_user/copy_from_user to the minimum that *does* need to be inlined - object size checks, basically. For another, it sanitizes the checks for iov_iter primitives. There are 4 groups of checks: access_ok(), might_fault(), object size and KASAN. - access_ok() had been verified by whoever had set the iov_iter up. However, that has happened in a function far away, so proving that there's no path to actual copying bypassing those checks is hard and proving that iov_iter has not been buggered in the meanwhile is also not pleasant. So we want those redone in actual copyin/copyout. - might_fault() is better off consolidated - we know whether it needs to be checked as soon as we enter iov_iter primitive and observe the iov_iter flavour. No need to wait until the copyin/copyout. The call chains are short enough to make sure we won't miss anything - in fact, it's more robust that way, since there are cases where we do e.g. forced fault-in before getting to copyin/copyout. It's not quite what we need to check (in particular, combination of iovec-backed and set_fs(KERNEL_DS) is almost certainly a bug, not a cause to skip checks), but that's for later series. For now let's keep might_fault(). - KASAN checks belong in copyin/copyout - at the same level where other iov_iter flavours would've hit them in memcpy(). - object size checks should apply to *all* iov_iter flavours, not just iovec-backed ones. There are two groups of primitives - one gets the kernel object described as pointer + size (copy_to_iter(), etc.) while another gets it as page + offset + size (copy_page_to_iter(), etc.) For the first group the checks are best done where we actually have a chance to find the object size. In other words, those belong in inline wrappers in uio.h, before calling into iov_iter.c. Same kind as we have for inlined part of copy_to_user(). For the second group there is no object to look at - offset in page is just a number, it bears no type information. So we do them in the common helper called by iov_iter.c primitives of that kind. All it currently does is checking that we are not trying to access outside of the compound page; eventually we might want to add some sanity checks on the page involved. So the things we need in copyin/copyout part of iov_iter.c do not quite match anything in uaccess.h (we want no zeroing, we *do* want access_ok() and KASAN and we want no might_fault() or object size checks done on that level). OTOH, these needs are simple enough to provide a couple of helpers (static in iov_iter.c) doing just what we need..." * 'uaccess-work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: iov_iter: saner checks on copyin/copyout iov_iter: sanity checks for copy to/from page primitives iov_iter/hardening: move object size checks to inlined part copy_{to,from}_user(): consolidate object size checks copy_{from,to}_user(): move kasan checks and might_fault() out-of-line
2017-07-08 05:39:20 +02:00
size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i)
x86, uaccess: introduce copy_from_iter_flushcache for pmem / cache-bypass operations The pmem driver has a need to transfer data with a persistent memory destination and be able to rely on the fact that the destination writes are not cached. It is sufficient for the writes to be flushed to a cpu-store-buffer (non-temporal / "movnt" in x86 terms), as we expect userspace to call fsync() to ensure data-writes have reached a power-fail-safe zone in the platform. The fsync() triggers a REQ_FUA or REQ_FLUSH to the pmem driver which will turn around and fence previous writes with an "sfence". Implement a __copy_from_user_inatomic_flushcache, memcpy_page_flushcache, and memcpy_flushcache, that guarantee that the destination buffer is not dirty in the cpu cache on completion. The new copy_from_iter_flushcache and sub-routines will be used to replace the "pmem api" (include/linux/pmem.h + arch/x86/include/asm/pmem.h). The availability of copy_from_iter_flushcache() and memcpy_flushcache() are gated by the CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE config symbol, and fallback to copy_from_iter_nocache() and plain memcpy() otherwise. This is meant to satisfy the concern from Linus that if a driver wants to do something beyond the normal nocache semantics it should be something private to that driver [1], and Al's concern that anything uaccess related belongs with the rest of the uaccess code [2]. The first consumer of this interface is a new 'copy_from_iter' dax operation so that pmem can inject cache maintenance operations without imposing this overhead on other dax-capable drivers. [1]: https://lists.01.org/pipermail/linux-nvdimm/2017-January/008364.html [2]: https://lists.01.org/pipermail/linux-nvdimm/2017-April/009942.html Cc: <x86@kernel.org> Cc: Jan Kara <jack@suse.cz> Cc: Jeff Moyer <jmoyer@redhat.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Toshi Kani <toshi.kani@hpe.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Matthew Wilcox <mawilcox@microsoft.com> Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-05-29 21:22:50 +02:00
{
char *to = addr;
if (unlikely(i->type & ITER_PIPE)) {
WARN_ON(1);
return 0;
}
iterate_and_advance(i, bytes, v,
__copy_from_user_flushcache((to += v.iov_len) - v.iov_len,
v.iov_base, v.iov_len),
memcpy_page_flushcache((to += v.bv_len) - v.bv_len, v.bv_page,
v.bv_offset, v.bv_len),
memcpy_flushcache((to += v.iov_len) - v.iov_len, v.iov_base,
v.iov_len)
)
return bytes;
}
Merge branch 'uaccess-work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull iov_iter hardening from Al Viro: "This is the iov_iter/uaccess/hardening pile. For one thing, it trims the inline part of copy_to_user/copy_from_user to the minimum that *does* need to be inlined - object size checks, basically. For another, it sanitizes the checks for iov_iter primitives. There are 4 groups of checks: access_ok(), might_fault(), object size and KASAN. - access_ok() had been verified by whoever had set the iov_iter up. However, that has happened in a function far away, so proving that there's no path to actual copying bypassing those checks is hard and proving that iov_iter has not been buggered in the meanwhile is also not pleasant. So we want those redone in actual copyin/copyout. - might_fault() is better off consolidated - we know whether it needs to be checked as soon as we enter iov_iter primitive and observe the iov_iter flavour. No need to wait until the copyin/copyout. The call chains are short enough to make sure we won't miss anything - in fact, it's more robust that way, since there are cases where we do e.g. forced fault-in before getting to copyin/copyout. It's not quite what we need to check (in particular, combination of iovec-backed and set_fs(KERNEL_DS) is almost certainly a bug, not a cause to skip checks), but that's for later series. For now let's keep might_fault(). - KASAN checks belong in copyin/copyout - at the same level where other iov_iter flavours would've hit them in memcpy(). - object size checks should apply to *all* iov_iter flavours, not just iovec-backed ones. There are two groups of primitives - one gets the kernel object described as pointer + size (copy_to_iter(), etc.) while another gets it as page + offset + size (copy_page_to_iter(), etc.) For the first group the checks are best done where we actually have a chance to find the object size. In other words, those belong in inline wrappers in uio.h, before calling into iov_iter.c. Same kind as we have for inlined part of copy_to_user(). For the second group there is no object to look at - offset in page is just a number, it bears no type information. So we do them in the common helper called by iov_iter.c primitives of that kind. All it currently does is checking that we are not trying to access outside of the compound page; eventually we might want to add some sanity checks on the page involved. So the things we need in copyin/copyout part of iov_iter.c do not quite match anything in uaccess.h (we want no zeroing, we *do* want access_ok() and KASAN and we want no might_fault() or object size checks done on that level). OTOH, these needs are simple enough to provide a couple of helpers (static in iov_iter.c) doing just what we need..." * 'uaccess-work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: iov_iter: saner checks on copyin/copyout iov_iter: sanity checks for copy to/from page primitives iov_iter/hardening: move object size checks to inlined part copy_{to,from}_user(): consolidate object size checks copy_{from,to}_user(): move kasan checks and might_fault() out-of-line
2017-07-08 05:39:20 +02:00
EXPORT_SYMBOL_GPL(_copy_from_iter_flushcache);
x86, uaccess: introduce copy_from_iter_flushcache for pmem / cache-bypass operations The pmem driver has a need to transfer data with a persistent memory destination and be able to rely on the fact that the destination writes are not cached. It is sufficient for the writes to be flushed to a cpu-store-buffer (non-temporal / "movnt" in x86 terms), as we expect userspace to call fsync() to ensure data-writes have reached a power-fail-safe zone in the platform. The fsync() triggers a REQ_FUA or REQ_FLUSH to the pmem driver which will turn around and fence previous writes with an "sfence". Implement a __copy_from_user_inatomic_flushcache, memcpy_page_flushcache, and memcpy_flushcache, that guarantee that the destination buffer is not dirty in the cpu cache on completion. The new copy_from_iter_flushcache and sub-routines will be used to replace the "pmem api" (include/linux/pmem.h + arch/x86/include/asm/pmem.h). The availability of copy_from_iter_flushcache() and memcpy_flushcache() are gated by the CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE config symbol, and fallback to copy_from_iter_nocache() and plain memcpy() otherwise. This is meant to satisfy the concern from Linus that if a driver wants to do something beyond the normal nocache semantics it should be something private to that driver [1], and Al's concern that anything uaccess related belongs with the rest of the uaccess code [2]. The first consumer of this interface is a new 'copy_from_iter' dax operation so that pmem can inject cache maintenance operations without imposing this overhead on other dax-capable drivers. [1]: https://lists.01.org/pipermail/linux-nvdimm/2017-January/008364.html [2]: https://lists.01.org/pipermail/linux-nvdimm/2017-April/009942.html Cc: <x86@kernel.org> Cc: Jan Kara <jack@suse.cz> Cc: Jeff Moyer <jmoyer@redhat.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Toshi Kani <toshi.kani@hpe.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Matthew Wilcox <mawilcox@microsoft.com> Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-05-29 21:22:50 +02:00
#endif
bool _copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i)
{
char *to = addr;
if (unlikely(i->type & ITER_PIPE)) {
WARN_ON(1);
return false;
}
if (unlikely(i->count < bytes))
return false;
iterate_all_kinds(i, bytes, v, ({
if (__copy_from_user_inatomic_nocache((to += v.iov_len) - v.iov_len,
v.iov_base, v.iov_len))
return false;
0;}),
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)
)
iov_iter_advance(i, bytes);
return true;
}
EXPORT_SYMBOL(_copy_from_iter_full_nocache);
static inline bool page_copy_sane(struct page *page, size_t offset, size_t n)
{
struct page *head = compound_head(page);
size_t v = n + offset + page_address(page) - page_address(head);
if (likely(n <= v && v <= (PAGE_SIZE << compound_order(head))))
return true;
WARN_ON(1);
return false;
}
size_t copy_page_to_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 (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(!page_copy_sane(page, offset, bytes)))
return 0;
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(!page_copy_sane(page, offset, bytes))) {
kunmap_atomic(kaddr);
return 0;
}
if (unlikely(i->type & ITER_PIPE)) {
kunmap_atomic(kaddr);
WARN_ON(1);
return 0;
}
iterate_all_kinds(i, bytes, v,
copyin((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 inline void pipe_truncate(struct iov_iter *i)
{
struct pipe_inode_info *pipe = i->pipe;
if (pipe->nrbufs) {
size_t off = i->iov_offset;
int idx = i->idx;
int nrbufs = (idx - pipe->curbuf) & (pipe->buffers - 1);
if (off) {
pipe->bufs[idx].len = off - pipe->bufs[idx].offset;
idx = next_idx(idx, pipe);
nrbufs++;
}
while (pipe->nrbufs > nrbufs) {
pipe_buf_release(pipe, &pipe->bufs[idx]);
idx = next_idx(idx, pipe);
pipe->nrbufs--;
}
}
}
static void pipe_advance(struct iov_iter *i, size_t size)
{
struct pipe_inode_info *pipe = i->pipe;
if (unlikely(i->count < size))
size = i->count;
if (size) {
struct pipe_buffer *buf;
size_t off = i->iov_offset, left = size;
int idx = i->idx;
if (off) /* make it relative to the beginning of buffer */
left += off - pipe->bufs[idx].offset;
while (1) {
buf = &pipe->bufs[idx];
if (left <= buf->len)
break;
left -= buf->len;
idx = next_idx(idx, pipe);
}
i->idx = idx;
i->iov_offset = buf->offset + left;
}
i->count -= size;
/* ... and discard everything past that point */
pipe_truncate(i);
}
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);
void iov_iter_revert(struct iov_iter *i, size_t unroll)
{
if (!unroll)
return;
if (WARN_ON(unroll > MAX_RW_COUNT))
return;
i->count += unroll;
if (unlikely(i->type & ITER_PIPE)) {
struct pipe_inode_info *pipe = i->pipe;
int idx = i->idx;
size_t off = i->iov_offset;
while (1) {
size_t n = off - pipe->bufs[idx].offset;
if (unroll < n) {
off -= unroll;
break;
}
unroll -= n;
if (!unroll && idx == i->start_idx) {
off = 0;
break;
}
if (!idx--)
idx = pipe->buffers - 1;
off = pipe->bufs[idx].offset + pipe->bufs[idx].len;
}
i->iov_offset = off;
i->idx = idx;
pipe_truncate(i);
return;
}
if (unroll <= i->iov_offset) {
i->iov_offset -= unroll;
return;
}
unroll -= i->iov_offset;
if (i->type & ITER_BVEC) {
const struct bio_vec *bvec = i->bvec;
while (1) {
size_t n = (--bvec)->bv_len;
i->nr_segs++;
if (unroll <= n) {
i->bvec = bvec;
i->iov_offset = n - unroll;
return;
}
unroll -= n;
}
} else { /* same logics for iovec and kvec */
const struct iovec *iov = i->iov;
while (1) {
size_t n = (--iov)->iov_len;
i->nr_segs++;
if (unroll <= n) {
i->iov = iov;
i->iov_offset = n - unroll;
return;
}
unroll -= n;
}
}
}
EXPORT_SYMBOL(iov_iter_revert);
/*
* 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);
WARN_ON(pipe->nrbufs == pipe->buffers);
i->type = direction;
i->pipe = pipe;
i->idx = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1);
i->iov_offset = 0;
i->count = count;
i->start_idx = i->idx;
}
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 (unlikely(i->type & ITER_PIPE)) {
if (size && 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 (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 ssize_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 (!maxsize)
return 0;
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 (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)
{
treewide: use kv[mz]alloc* rather than opencoded variants There are many code paths opencoding kvmalloc. Let's use the helper instead. The main difference to kvmalloc is that those users are usually not considering all the aspects of the memory allocator. E.g. allocation requests <= 32kB (with 4kB pages) are basically never failing and invoke OOM killer to satisfy the allocation. This sounds too disruptive for something that has a reasonable fallback - the vmalloc. On the other hand those requests might fallback to vmalloc even when the memory allocator would succeed after several more reclaim/compaction attempts previously. There is no guarantee something like that happens though. This patch converts many of those places to kv[mz]alloc* helpers because they are more conservative. Link: http://lkml.kernel.org/r/20170306103327.2766-2-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> # Xen bits Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Andreas Dilger <andreas.dilger@intel.com> # Lustre Acked-by: Christian Borntraeger <borntraeger@de.ibm.com> # KVM/s390 Acked-by: Dan Williams <dan.j.williams@intel.com> # nvdim Acked-by: David Sterba <dsterba@suse.com> # btrfs Acked-by: Ilya Dryomov <idryomov@gmail.com> # Ceph Acked-by: Tariq Toukan <tariqt@mellanox.com> # mlx4 Acked-by: Leon Romanovsky <leonro@mellanox.com> # mlx5 Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Anton Vorontsov <anton@enomsg.org> Cc: Colin Cross <ccross@android.com> Cc: Tony Luck <tony.luck@intel.com> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: Ben Skeggs <bskeggs@redhat.com> Cc: Kent Overstreet <kent.overstreet@gmail.com> Cc: Santosh Raspatur <santosh@chelsio.com> Cc: Hariprasad S <hariprasad@chelsio.com> Cc: Yishai Hadas <yishaih@mellanox.com> Cc: Oleg Drokin <oleg.drokin@intel.com> Cc: "Yan, Zheng" <zyan@redhat.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: David Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-05-09 00:57:27 +02:00
return kvmalloc_array(n, sizeof(struct page *), GFP_KERNEL);
}
static ssize_t pipe_get_pages_alloc(struct iov_iter *i,
struct page ***pages, size_t maxsize,
size_t *start)
{
struct page **p;
ssize_t n;
int idx;
int npages;
if (!maxsize)
return 0;
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 (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);
bool csum_and_copy_from_iter_full(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 false;
}
if (unlikely(i->count < bytes))
return false;
iterate_all_kinds(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)
return false;
sum = csum_block_add(sum, next, off);
off += 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;
iov_iter_advance(i, bytes);
return true;
}
EXPORT_SYMBOL(csum_and_copy_from_iter_full);
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);
saner iov_iter initialization primitives iovec-backed iov_iter instances are assumed to satisfy several properties: * no more than UIO_MAXIOV elements in iovec array * total size of all ranges is no more than MAX_RW_COUNT * all ranges pass access_ok(). The problem is, invariants of data structures should be established in the primitives creating those data structures, not in the code using those primitives. And iov_iter_init() violates that principle. For a while we managed to get away with that, but once the use of iov_iter started to spread, it didn't take long for shit to hit the fan - missed check in sys_sendto() had introduced a roothole. We _do_ have primitives for importing and validating iovecs (both native and compat ones) and those primitives are almost always followed by shoving the resulting iovec into iov_iter. Life would be considerably simpler (and safer) if we combined those primitives with initializing iov_iter. That gives us two new primitives - import_iovec() and compat_import_iovec(). Calling conventions: iovec = iov_array; err = import_iovec(direction, uvec, nr_segs, ARRAY_SIZE(iov_array), &iovec, &iter); imports user vector into kernel space (into iov_array if it fits, allocated if it doesn't fit or if iovec was NULL), validates it and sets iter up to refer to it. On success 0 is returned and allocated kernel copy (or NULL if the array had fit into caller-supplied one) is returned via iovec. On failure all allocations are undone and -E... is returned. If the total size of ranges exceeds MAX_RW_COUNT, the excess is silently truncated. compat_import_iovec() expects uvec to be a pointer to user array of compat_iovec; otherwise it's identical to import_iovec(). Finally, import_single_range() sets iov_iter backed by single-element iovec covering a user-supplied range - err = import_single_range(direction, address, size, iovec, &iter); does validation and sets iter up. Again, size in excess of MAX_RW_COUNT gets silently truncated. Next commits will be switching the things up to use of those and reducing the amount of iov_iter_init() instances. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-03-21 22:45:43 +01:00
/**
* 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.
*/
saner iov_iter initialization primitives iovec-backed iov_iter instances are assumed to satisfy several properties: * no more than UIO_MAXIOV elements in iovec array * total size of all ranges is no more than MAX_RW_COUNT * all ranges pass access_ok(). The problem is, invariants of data structures should be established in the primitives creating those data structures, not in the code using those primitives. And iov_iter_init() violates that principle. For a while we managed to get away with that, but once the use of iov_iter started to spread, it didn't take long for shit to hit the fan - missed check in sys_sendto() had introduced a roothole. We _do_ have primitives for importing and validating iovecs (both native and compat ones) and those primitives are almost always followed by shoving the resulting iovec into iov_iter. Life would be considerably simpler (and safer) if we combined those primitives with initializing iov_iter. That gives us two new primitives - import_iovec() and compat_import_iovec(). Calling conventions: iovec = iov_array; err = import_iovec(direction, uvec, nr_segs, ARRAY_SIZE(iov_array), &iovec, &iter); imports user vector into kernel space (into iov_array if it fits, allocated if it doesn't fit or if iovec was NULL), validates it and sets iter up to refer to it. On success 0 is returned and allocated kernel copy (or NULL if the array had fit into caller-supplied one) is returned via iovec. On failure all allocations are undone and -E... is returned. If the total size of ranges exceeds MAX_RW_COUNT, the excess is silently truncated. compat_import_iovec() expects uvec to be a pointer to user array of compat_iovec; otherwise it's identical to import_iovec(). Finally, import_single_range() sets iov_iter backed by single-element iovec covering a user-supplied range - err = import_single_range(direction, address, size, iovec, &iter); does validation and sets iter up. Again, size in excess of MAX_RW_COUNT gets silently truncated. Next commits will be switching the things up to use of those and reducing the amount of iov_iter_init() instances. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-03-21 22:45:43 +01:00
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);
int iov_iter_for_each_range(struct iov_iter *i, size_t bytes,
int (*f)(struct kvec *vec, void *context),
void *context)
{
struct kvec w;
int err = -EINVAL;
if (!bytes)
return 0;
iterate_all_kinds(i, bytes, v, -EINVAL, ({
w.iov_base = kmap(v.bv_page) + v.bv_offset;
w.iov_len = v.bv_len;
err = f(&w, context);
kunmap(v.bv_page);
err;}), ({
w = v;
err = f(&w, context);})
)
return err;
}
EXPORT_SYMBOL(iov_iter_for_each_range);