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iov_iter: saner checks on copyin/copyout

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* might_fault() is better checked in caller (and e.g. fault-in + kmap_atomic
codepath also needs might_fault() coverage)
* we have already done object size checks
* we have *NOT* done access_ok() recently enough; we rely upon the
iovec array having passed sanity checks back when it had been created
and not nothing having buggered it since.  However, that's very much
non-local, so we'd better recheck that.

So the thing we want does not match anything in uaccess - we need
access_ok + kasan checks + raw copy without any zeroing.  Just define
such helpers and use them here.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2017-06-29 22:25:14 -04:00
parent 72e809ed81
commit 09fc68dc66
1 changed files with 39 additions and 16 deletions
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55
lib/iov_iter.c
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@ -130,6 +130,24 @@
} \
}
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)
{
@ -144,6 +162,7 @@ static size_t copy_page_to_iter_iovec(struct page *page, size_t offset, size_t b
if (unlikely(!bytes))
return 0;
might_fault();
wanted = bytes;
iov = i->iov;
skip = i->iov_offset;
@ -155,7 +174,7 @@ static size_t copy_page_to_iter_iovec(struct page *page, size_t offset, size_t b
from = kaddr + offset;
/* first chunk, usually the only one */
left = __copy_to_user_inatomic(buf, from, copy);
left = copyout(buf, from, copy);
copy -= left;
skip += copy;
from += copy;
@ -165,7 +184,7 @@ static size_t copy_page_to_iter_iovec(struct page *page, size_t offset, size_t b
iov++;
buf = iov->iov_base;
copy = min(bytes, iov->iov_len);
left = __copy_to_user_inatomic(buf, from, copy);
left = copyout(buf, from, copy);
copy -= left;
skip = copy;
from += copy;
@ -184,7 +203,7 @@ static size_t copy_page_to_iter_iovec(struct page *page, size_t offset, size_t b
kaddr = kmap(page);
from = kaddr + offset;
left = __copy_to_user(buf, from, copy);
left = copyout(buf, from, copy);
copy -= left;
skip += copy;
from += copy;
@ -193,7 +212,7 @@ static size_t copy_page_to_iter_iovec(struct page *page, size_t offset, size_t b
iov++;
buf = iov->iov_base;
copy = min(bytes, iov->iov_len);
left = __copy_to_user(buf, from, copy);
left = copyout(buf, from, copy);
copy -= left;
skip = copy;
from += copy;
@ -227,6 +246,7 @@ static size_t copy_page_from_iter_iovec(struct page *page, size_t offset, size_t
if (unlikely(!bytes))
return 0;
might_fault();
wanted = bytes;
iov = i->iov;
skip = i->iov_offset;
@ -238,7 +258,7 @@ static size_t copy_page_from_iter_iovec(struct page *page, size_t offset, size_t
to = kaddr + offset;
/* first chunk, usually the only one */
left = __copy_from_user_inatomic(to, buf, copy);
left = copyin(to, buf, copy);
copy -= left;
skip += copy;
to += copy;
@ -248,7 +268,7 @@ static size_t copy_page_from_iter_iovec(struct page *page, size_t offset, size_t
iov++;
buf = iov->iov_base;
copy = min(bytes, iov->iov_len);
left = __copy_from_user_inatomic(to, buf, copy);
left = copyin(to, buf, copy);
copy -= left;
skip = copy;
to += copy;
@ -267,7 +287,7 @@ static size_t copy_page_from_iter_iovec(struct page *page, size_t offset, size_t
kaddr = kmap(page);
to = kaddr + offset;
left = __copy_from_user(to, buf, copy);
left = copyin(to, buf, copy);
copy -= left;
skip += copy;
to += copy;
@ -276,7 +296,7 @@ static size_t copy_page_from_iter_iovec(struct page *page, size_t offset, size_t
iov++;
buf = iov->iov_base;
copy = min(bytes, iov->iov_len);
left = __copy_from_user(to, buf, copy);
left = copyin(to, buf, copy);
copy -= left;
skip = copy;
to += copy;
@ -540,9 +560,10 @@ 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,
__copy_to_user(v.iov_base, (from += v.iov_len) - v.iov_len,
v.iov_len),
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)
@ -559,9 +580,10 @@ size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
WARN_ON(1);
return 0;
}
if (iter_is_iovec(i))
might_fault();
iterate_and_advance(i, bytes, v,
__copy_from_user((to += v.iov_len) - v.iov_len, v.iov_base,
v.iov_len),
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)
@ -581,8 +603,10 @@ bool _copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i)
if (unlikely(i->count < bytes))
return false;
if (iter_is_iovec(i))
might_fault();
iterate_all_kinds(i, bytes, v, ({
if (__copy_from_user((to += v.iov_len) - v.iov_len,
if (copyin((to += v.iov_len) - v.iov_len,
v.iov_base, v.iov_len))
return false;
0;}),
@ -713,7 +737,7 @@ 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),
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)
)
@ -736,8 +760,7 @@ size_t iov_iter_copy_from_user_atomic(struct page *page,
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),
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)