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Message-Id: <20211214162050.660953-5-glider@google.com>
Date: Tue, 14 Dec 2021 17:20:11 +0100
From: Alexander Potapenko <glider@...gle.com>
To: glider@...gle.com
Cc: Alexander Viro <viro@...iv.linux.org.uk>,
Andrew Morton <akpm@...ux-foundation.org>,
Andrey Konovalov <andreyknvl@...gle.com>,
Andy Lutomirski <luto@...nel.org>,
Ard Biesheuvel <ard.biesheuvel@...aro.org>,
Arnd Bergmann <arnd@...db.de>, Borislav Petkov <bp@...en8.de>,
Christoph Hellwig <hch@....de>,
Christoph Lameter <cl@...ux.com>,
David Rientjes <rientjes@...gle.com>,
Dmitry Vyukov <dvyukov@...gle.com>,
Eric Dumazet <edumazet@...gle.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Herbert Xu <herbert@...dor.apana.org.au>,
Ilya Leoshkevich <iii@...ux.ibm.com>,
Ingo Molnar <mingo@...hat.com>, Jens Axboe <axboe@...nel.dk>,
Joonsoo Kim <iamjoonsoo.kim@....com>,
Kees Cook <keescook@...omium.org>,
Marco Elver <elver@...gle.com>,
Matthew Wilcox <willy@...radead.org>,
"Michael S. Tsirkin" <mst@...hat.com>,
Pekka Enberg <penberg@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Petr Mladek <pmladek@...e.com>,
Steven Rostedt <rostedt@...dmis.org>,
Thomas Gleixner <tglx@...utronix.de>,
Vasily Gorbik <gor@...ux.ibm.com>,
Vegard Nossum <vegard.nossum@...cle.com>,
Vlastimil Babka <vbabka@...e.cz>, linux-mm@...ck.org,
linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 04/43] instrumented.h: allow instrumenting both sides of copy_from_user()
Introduce instrument_copy_from_user_before() and
instrument_copy_from_user_after() hooks to be invoked before and after
the call to copy_from_user().
KASAN and KCSAN will be only using instrument_copy_from_user_before(),
but for KMSAN we'll need to insert code after copy_from_user().
Signed-off-by: Alexander Potapenko <glider@...gle.com>
---
Link: https://linux-review.googlesource.com/id/I855034578f0b0f126734cbd734fb4ae1d3a6af99
---
include/linux/instrumented.h | 21 +++++++++++++++++++--
include/linux/uaccess.h | 19 ++++++++++++++-----
lib/iov_iter.c | 9 ++++++---
lib/usercopy.c | 3 ++-
4 files changed, 41 insertions(+), 11 deletions(-)
diff --git a/include/linux/instrumented.h b/include/linux/instrumented.h
index 42faebbaa202a..ee8f7d17d34f5 100644
--- a/include/linux/instrumented.h
+++ b/include/linux/instrumented.h
@@ -120,7 +120,7 @@ instrument_copy_to_user(void __user *to, const void *from, unsigned long n)
}
/**
- * instrument_copy_from_user - instrument writes of copy_from_user
+ * instrument_copy_from_user_before - add instrumentation before copy_from_user
*
* Instrument writes to kernel memory, that are due to copy_from_user (and
* variants). The instrumentation should be inserted before the accesses.
@@ -130,10 +130,27 @@ instrument_copy_to_user(void __user *to, const void *from, unsigned long n)
* @n number of bytes to copy
*/
static __always_inline void
-instrument_copy_from_user(const void *to, const void __user *from, unsigned long n)
+instrument_copy_from_user_before(const void *to, const void __user *from, unsigned long n)
{
kasan_check_write(to, n);
kcsan_check_write(to, n);
}
+/**
+ * instrument_copy_from_user_after - add instrumentation after copy_from_user
+ *
+ * Instrument writes to kernel memory, that are due to copy_from_user (and
+ * variants). The instrumentation should be inserted after the accesses.
+ *
+ * @to destination address
+ * @from source address
+ * @n number of bytes to copy
+ * @left number of bytes not copied (as returned by copy_from_user)
+ */
+static __always_inline void
+instrument_copy_from_user_after(const void *to, const void __user *from,
+ unsigned long n, unsigned long left)
+{
+}
+
#endif /* _LINUX_INSTRUMENTED_H */
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index ac0394087f7d4..8dadd8642afbb 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -98,20 +98,28 @@ static inline void force_uaccess_end(mm_segment_t oldfs)
static __always_inline __must_check unsigned long
__copy_from_user_inatomic(void *to, const void __user *from, unsigned long n)
{
- instrument_copy_from_user(to, from, n);
+ unsigned long res;
+
+ instrument_copy_from_user_before(to, from, n);
check_object_size(to, n, false);
- return raw_copy_from_user(to, from, n);
+ res = raw_copy_from_user(to, from, n);
+ instrument_copy_from_user_after(to, from, n, res);
+ return res;
}
static __always_inline __must_check unsigned long
__copy_from_user(void *to, const void __user *from, unsigned long n)
{
+ unsigned long res;
+
might_fault();
+ instrument_copy_from_user_before(to, from, n);
if (should_fail_usercopy())
return n;
- instrument_copy_from_user(to, from, n);
check_object_size(to, n, false);
- return raw_copy_from_user(to, from, n);
+ res = raw_copy_from_user(to, from, n);
+ instrument_copy_from_user_after(to, from, n, res);
+ return res;
}
/**
@@ -155,8 +163,9 @@ _copy_from_user(void *to, const void __user *from, unsigned long n)
unsigned long res = n;
might_fault();
if (!should_fail_usercopy() && likely(access_ok(from, n))) {
- instrument_copy_from_user(to, from, n);
+ instrument_copy_from_user_before(to, from, n);
res = raw_copy_from_user(to, from, n);
+ instrument_copy_from_user_after(to, from, n, res);
}
if (unlikely(res))
memset(to + (n - res), 0, res);
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 66a740e6e153c..28c033cb9e803 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -161,13 +161,16 @@ static int copyout(void __user *to, const void *from, size_t n)
static int copyin(void *to, const void __user *from, size_t n)
{
+ size_t res = n;
+
if (should_fail_usercopy())
return n;
if (access_ok(from, n)) {
- instrument_copy_from_user(to, from, n);
- n = raw_copy_from_user(to, from, n);
+ instrument_copy_from_user_before(to, from, n);
+ res = raw_copy_from_user(to, from, n);
+ instrument_copy_from_user_after(to, from, n, res);
}
- return n;
+ return res;
}
static size_t copy_page_to_iter_iovec(struct page *page, size_t offset, size_t bytes,
diff --git a/lib/usercopy.c b/lib/usercopy.c
index 7413dd300516e..1505a52f23a01 100644
--- a/lib/usercopy.c
+++ b/lib/usercopy.c
@@ -12,8 +12,9 @@ unsigned long _copy_from_user(void *to, const void __user *from, unsigned long n
unsigned long res = n;
might_fault();
if (!should_fail_usercopy() && likely(access_ok(from, n))) {
- instrument_copy_from_user(to, from, n);
+ instrument_copy_from_user_before(to, from, n);
res = raw_copy_from_user(to, from, n);
+ instrument_copy_from_user_after(to, from, n, res);
}
if (unlikely(res))
memset(to + (n - res), 0, res);
--
2.34.1.173.g76aa8bc2d0-goog
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