From 33b75c1d884e81ec97525e0a6fdcb187adf273f4 Mon Sep 17 00:00:00 2001 From: Alexander Potapenko Date: Thu, 15 Sep 2022 17:03:37 +0200 Subject: [PATCH] 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(). Link: https://lkml.kernel.org/r/20220915150417.722975-4-glider@google.com Signed-off-by: Alexander Potapenko Reviewed-by: Marco Elver Cc: Alexander Viro Cc: Alexei Starovoitov Cc: Andrey Konovalov Cc: Andrey Konovalov Cc: Andy Lutomirski Cc: Arnd Bergmann Cc: Borislav Petkov Cc: Christoph Hellwig Cc: Christoph Lameter Cc: David Rientjes Cc: Dmitry Vyukov Cc: Eric Biggers Cc: Eric Biggers Cc: Eric Dumazet Cc: Greg Kroah-Hartman Cc: Herbert Xu Cc: Ilya Leoshkevich Cc: Ingo Molnar Cc: Jens Axboe Cc: Joonsoo Kim Cc: Kees Cook Cc: Mark Rutland Cc: Matthew Wilcox Cc: Michael S. Tsirkin Cc: Pekka Enberg Cc: Peter Zijlstra Cc: Petr Mladek Cc: Stephen Rothwell Cc: Steven Rostedt Cc: Thomas Gleixner Cc: Vasily Gorbik Cc: Vegard Nossum Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- arch/s390/lib/uaccess.c | 3 ++- include/linux/instrumented.h | 21 +++++++++++++++++++-- include/linux/uaccess.h | 19 ++++++++++++++----- lib/iov_iter.c | 9 ++++++--- lib/usercopy.c | 3 ++- 5 files changed, 43 insertions(+), 12 deletions(-) diff --git a/arch/s390/lib/uaccess.c b/arch/s390/lib/uaccess.c index d7b3b193d108..58033dfcb6d4 100644 --- a/arch/s390/lib/uaccess.c +++ b/arch/s390/lib/uaccess.c @@ -81,8 +81,9 @@ unsigned long _copy_from_user_key(void *to, const void __user *from, might_fault(); if (!should_fail_usercopy()) { - instrument_copy_from_user(to, from, n); + instrument_copy_from_user_before(to, from, n); res = raw_copy_from_user_key(to, from, n, key); + instrument_copy_from_user_after(to, from, n, res); } if (unlikely(res)) memset(to + (n - res), 0, res); diff --git a/include/linux/instrumented.h b/include/linux/instrumented.h index 42faebbaa202..ee8f7d17d34f 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 47e5d374c7eb..afb18f198843 100644 --- a/include/linux/uaccess.h +++ b/include/linux/uaccess.h @@ -58,20 +58,28 @@ 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; } /** @@ -115,8 +123,9 @@ _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 4b7fce72e3e5..c3ca28ca68a6 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -174,13 +174,16 @@ 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 inline struct pipe_buffer *pipe_buf(const struct pipe_inode_info *pipe, diff --git a/lib/usercopy.c b/lib/usercopy.c index 7413dd300516..1505a52f23a0 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); -- 2.20.1