From 09fc68dc66f7597bdc8898c991609a48f061bed5 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Thu, 29 Jun 2017 22:25:14 -0400 Subject: [PATCH] iov_iter: saner checks on copyin/copyout * 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 --- lib/iov_iter.c | 55 +++++++++++++++++++++++++++++++++++--------------- 1 file changed, 39 insertions(+), 16 deletions(-) diff --git a/lib/iov_iter.c b/lib/iov_iter.c index b50a478f9d34..b3b2ee8a20b5 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -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) -- 2.34.1