From: Albert van der Linde <alinde@xxxxxxxxxx> Subject: lib, uaccess: add failure injection to usercopy functions To test fault-tolerance of user memory access functions, introduce fault injection to usercopy functions. If a failure is expected return either -EFAULT or the total amount of bytes that were not copied. Link: http://lkml.kernel.org/r/20200831171733.955393-3-alinde@xxxxxxxxxx Signed-off-by: Albert van der Linde <alinde@xxxxxxxxxx> Reviewed-by: Akinobu Mita <akinobu.mita@xxxxxxxxx> Reviewed-by: Alexander Potapenko <glider@xxxxxxxxxx> Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Cc: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Cc: Arnd Bergmann <arnd@xxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Jonathan Corbet <corbet@xxxxxxx> Cc: Marco Elver <elver@xxxxxxxxxx> Cc: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Christoph Hellwig <hch@xxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/uaccess.h | 11 ++++++++++- lib/iov_iter.c | 5 +++++ lib/strncpy_from_user.c | 3 +++ lib/usercopy.c | 5 ++++- 4 files changed, 22 insertions(+), 2 deletions(-) --- a/include/linux/uaccess.h~lib-uaccess-add-failure-injection-to-usercopy-functions +++ a/include/linux/uaccess.h @@ -2,6 +2,7 @@ #ifndef __LINUX_UACCESS_H__ #define __LINUX_UACCESS_H__ +#include <linux/fault-inject-usercopy.h> #include <linux/instrumented.h> #include <linux/minmax.h> #include <linux/sched.h> @@ -84,6 +85,8 @@ static __always_inline __must_check unsi __copy_from_user(void *to, const void __user *from, unsigned long n) { might_fault(); + 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); @@ -105,6 +108,8 @@ __copy_from_user(void *to, const void __ static __always_inline __must_check unsigned long __copy_to_user_inatomic(void __user *to, const void *from, unsigned long n) { + if (should_fail_usercopy()) + return n; instrument_copy_to_user(to, from, n); check_object_size(from, n, true); return raw_copy_to_user(to, from, n); @@ -114,6 +119,8 @@ static __always_inline __must_check unsi __copy_to_user(void __user *to, const void *from, unsigned long n) { might_fault(); + if (should_fail_usercopy()) + return n; instrument_copy_to_user(to, from, n); check_object_size(from, n, true); return raw_copy_to_user(to, from, n); @@ -125,7 +132,7 @@ _copy_from_user(void *to, const void __u { unsigned long res = n; might_fault(); - if (likely(access_ok(from, n))) { + if (!should_fail_usercopy() && likely(access_ok(from, n))) { instrument_copy_from_user(to, from, n); res = raw_copy_from_user(to, from, n); } @@ -143,6 +150,8 @@ static inline __must_check unsigned long _copy_to_user(void __user *to, const void *from, unsigned long n) { might_fault(); + if (should_fail_usercopy()) + return n; if (access_ok(to, n)) { instrument_copy_to_user(to, from, n); n = raw_copy_to_user(to, from, n); --- a/lib/iov_iter.c~lib-uaccess-add-failure-injection-to-usercopy-functions +++ a/lib/iov_iter.c @@ -2,6 +2,7 @@ #include <crypto/hash.h> #include <linux/export.h> #include <linux/bvec.h> +#include <linux/fault-inject-usercopy.h> #include <linux/uio.h> #include <linux/pagemap.h> #include <linux/slab.h> @@ -140,6 +141,8 @@ static int copyout(void __user *to, const void *from, size_t n) { + if (should_fail_usercopy()) + return n; if (access_ok(to, n)) { instrument_copy_to_user(to, from, n); n = raw_copy_to_user(to, from, n); @@ -149,6 +152,8 @@ static int copyout(void __user *to, cons static int copyin(void *to, const void __user *from, size_t 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); --- a/lib/strncpy_from_user.c~lib-uaccess-add-failure-injection-to-usercopy-functions +++ a/lib/strncpy_from_user.c @@ -1,6 +1,7 @@ // SPDX-License-Identifier: GPL-2.0 #include <linux/compiler.h> #include <linux/export.h> +#include <linux/fault-inject-usercopy.h> #include <linux/kasan-checks.h> #include <linux/thread_info.h> #include <linux/uaccess.h> @@ -99,6 +100,8 @@ long strncpy_from_user(char *dst, const unsigned long max_addr, src_addr; might_fault(); + if (should_fail_usercopy()) + return -EFAULT; if (unlikely(count <= 0)) return 0; --- a/lib/usercopy.c~lib-uaccess-add-failure-injection-to-usercopy-functions +++ a/lib/usercopy.c @@ -1,5 +1,6 @@ // SPDX-License-Identifier: GPL-2.0 #include <linux/bitops.h> +#include <linux/fault-inject-usercopy.h> #include <linux/instrumented.h> #include <linux/uaccess.h> @@ -10,7 +11,7 @@ unsigned long _copy_from_user(void *to, { unsigned long res = n; might_fault(); - if (likely(access_ok(from, n))) { + if (!should_fail_usercopy() && likely(access_ok(from, n))) { instrument_copy_from_user(to, from, n); res = raw_copy_from_user(to, from, n); } @@ -25,6 +26,8 @@ EXPORT_SYMBOL(_copy_from_user); unsigned long _copy_to_user(void __user *to, const void *from, unsigned long n) { might_fault(); + if (should_fail_usercopy()) + return n; if (likely(access_ok(to, n))) { instrument_copy_to_user(to, from, n); n = raw_copy_to_user(to, from, n); _
