From: Kees Cook <keescook@chromium.org> To: linux-kernel@vger.kernel.org Cc: Kees Cook <keescook@chromium.org>, Emese Revfy <re.emese@gmail.com>, Arnd Bergmann <arnd@arndb.de>, Josh Triplett <josh@joshtriplett.org>, pageexec@freemail.hu, yamada.masahiro@socionext.com, minipli@ld-linux.so, linux@armlinux.org.uk, catalin.marinas@arm.com, linux@rasmusvillemoes.dk, david.brown@linaro.org, benh@kernel.crashing.org, tglx@linutronix.de, akpm@linux-foundation.org, jlayton@poochiereds.net, sam@ravnborg.org, kernel-hardening@lists.openwall.com Subject: [PATCH v5 4/4] initify: Mark functions with the __unverified_nocapture attribute Date: Tue, 31 Jan 2017 12:24:22 -0800 [thread overview] Message-ID: <1485894263-91051-5-git-send-email-keescook@chromium.org> (raw) In-Reply-To: <1485894263-91051-1-git-send-email-keescook@chromium.org> From: Emese Revfy <re.emese@gmail.com> The initify plugin attempts to analyze function arguments that have been marked correctly with the __nocapture attribute. However, due to code complexity, this is not always possible to verify. As a result, some __nocapture attributes need to be marked as excluded from the automatic verification. To do this, the __unverified_nocapture attribute is added. It is intedned to only be used on function parameters that are difficult for the plugin to analyze. Signed-off-by: Emese Revfy <re.emese@gmail.com> Signed-off-by: Kees Cook <keescook@chromium.org> --- include/linux/compiler-gcc.h | 8 ++++++++ include/linux/compiler.h | 4 ++++ lib/vsprintf.c | 4 ++-- 3 files changed, 14 insertions(+), 2 deletions(-) diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h index cd4e9ffb00a7..fc0495e849ff 100644 --- a/include/linux/compiler-gcc.h +++ b/include/linux/compiler-gcc.h @@ -204,9 +204,17 @@ * been unmapped from memory. In order to identify functions that are confirmed * to not capture their arguments, the __nocapture() attribute is used so that * initify can better identify candidate variables. + * + * Arguments marked in this way are verified by the plugin, but sometimes + * code complexity and other limitiations will cause initify to not be able + * to check it correctly. For these cases, the __unverified_nocapture + * attribute can be added to disable this checking, overriding the plugin + * logic for cases that have been manually verified. This should not need + * to be used very often. */ #ifdef INITIFY_PLUGIN #define __nocapture(...) __attribute__((nocapture(__VA_ARGS__))) +#define __unverified_nocapture(...) __attribute__((unverified_nocapture(__VA_ARGS__))) #endif /* diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 8b3dcc790bb6..1bde420f07bb 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -437,6 +437,10 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s # define __nocapture(...) #endif +#ifndef __unverified_nocapture +# define __unverified_nocapture(...) +#endif + /* * Tell gcc if a function is cold. The compiler will assume any path * directly leading to the call is unlikely. diff --git a/lib/vsprintf.c b/lib/vsprintf.c index a192761d338a..cb964b51f9f8 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -118,7 +118,7 @@ long long simple_strtoll(const char *cp, char **endp, unsigned int base) } EXPORT_SYMBOL(simple_strtoll); -static noinline_for_stack __nocapture(1) +static noinline_for_stack __nocapture(1) __unverified_nocapture(1) int skip_atoi(const char **s) { int i = 0; @@ -1570,7 +1570,7 @@ int kptr_restrict __read_mostly; * function pointers are really function descriptors, which contain a * pointer to the real address. */ -static noinline_for_stack __nocapture(1) +static noinline_for_stack __nocapture(1) __unverified_nocapture(1) char *pointer(const char *fmt, char *buf, char *end, void *ptr, struct printf_spec spec) { -- 2.7.4
WARNING: multiple messages have this Message-ID (diff)
From: Kees Cook <keescook@chromium.org> To: linux-kernel@vger.kernel.org Cc: Kees Cook <keescook@chromium.org>, Emese Revfy <re.emese@gmail.com>, Arnd Bergmann <arnd@arndb.de>, Josh Triplett <josh@joshtriplett.org>, pageexec@freemail.hu, yamada.masahiro@socionext.com, minipli@ld-linux.so, linux@armlinux.org.uk, catalin.marinas@arm.com, linux@rasmusvillemoes.dk, david.brown@linaro.org, benh@kernel.crashing.org, tglx@linutronix.de, akpm@linux-foundation.org, jlayton@poochiereds.net, sam@ravnborg.org, kernel-hardening@lists.openwall.com Subject: [kernel-hardening] [PATCH v5 4/4] initify: Mark functions with the __unverified_nocapture attribute Date: Tue, 31 Jan 2017 12:24:22 -0800 [thread overview] Message-ID: <1485894263-91051-5-git-send-email-keescook@chromium.org> (raw) In-Reply-To: <1485894263-91051-1-git-send-email-keescook@chromium.org> From: Emese Revfy <re.emese@gmail.com> The initify plugin attempts to analyze function arguments that have been marked correctly with the __nocapture attribute. However, due to code complexity, this is not always possible to verify. As a result, some __nocapture attributes need to be marked as excluded from the automatic verification. To do this, the __unverified_nocapture attribute is added. It is intedned to only be used on function parameters that are difficult for the plugin to analyze. Signed-off-by: Emese Revfy <re.emese@gmail.com> Signed-off-by: Kees Cook <keescook@chromium.org> --- include/linux/compiler-gcc.h | 8 ++++++++ include/linux/compiler.h | 4 ++++ lib/vsprintf.c | 4 ++-- 3 files changed, 14 insertions(+), 2 deletions(-) diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h index cd4e9ffb00a7..fc0495e849ff 100644 --- a/include/linux/compiler-gcc.h +++ b/include/linux/compiler-gcc.h @@ -204,9 +204,17 @@ * been unmapped from memory. In order to identify functions that are confirmed * to not capture their arguments, the __nocapture() attribute is used so that * initify can better identify candidate variables. + * + * Arguments marked in this way are verified by the plugin, but sometimes + * code complexity and other limitiations will cause initify to not be able + * to check it correctly. For these cases, the __unverified_nocapture + * attribute can be added to disable this checking, overriding the plugin + * logic for cases that have been manually verified. This should not need + * to be used very often. */ #ifdef INITIFY_PLUGIN #define __nocapture(...) __attribute__((nocapture(__VA_ARGS__))) +#define __unverified_nocapture(...) __attribute__((unverified_nocapture(__VA_ARGS__))) #endif /* diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 8b3dcc790bb6..1bde420f07bb 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -437,6 +437,10 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s # define __nocapture(...) #endif +#ifndef __unverified_nocapture +# define __unverified_nocapture(...) +#endif + /* * Tell gcc if a function is cold. The compiler will assume any path * directly leading to the call is unlikely. diff --git a/lib/vsprintf.c b/lib/vsprintf.c index a192761d338a..cb964b51f9f8 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -118,7 +118,7 @@ long long simple_strtoll(const char *cp, char **endp, unsigned int base) } EXPORT_SYMBOL(simple_strtoll); -static noinline_for_stack __nocapture(1) +static noinline_for_stack __nocapture(1) __unverified_nocapture(1) int skip_atoi(const char **s) { int i = 0; @@ -1570,7 +1570,7 @@ int kptr_restrict __read_mostly; * function pointers are really function descriptors, which contain a * pointer to the real address. */ -static noinline_for_stack __nocapture(1) +static noinline_for_stack __nocapture(1) __unverified_nocapture(1) char *pointer(const char *fmt, char *buf, char *end, void *ptr, struct printf_spec spec) { -- 2.7.4
next prev parent reply other threads:[~2017-01-31 20:32 UTC|newest] Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-01-31 20:24 [PATCH v5 0/4] Introduce the initify gcc plugin Kees Cook 2017-01-31 20:24 ` [kernel-hardening] " Kees Cook 2017-01-31 20:24 ` [PATCH v5 1/4] gcc-plugins: Add " Kees Cook 2017-01-31 20:24 ` [kernel-hardening] " Kees Cook 2017-03-27 7:38 ` Andrew Donnellan 2017-03-27 16:14 ` Kees Cook 2017-03-27 16:14 ` Kees Cook 2017-03-27 19:31 ` Rasmus Villemoes 2017-03-27 19:31 ` [kernel-hardening] " Rasmus Villemoes 2017-03-27 19:33 ` Kees Cook 2017-03-27 19:33 ` [kernel-hardening] " Kees Cook 2017-03-28 7:49 ` [kernel-hardening] " Arnd Bergmann 2017-03-28 7:49 ` Arnd Bergmann 2017-03-28 19:03 ` Kees Cook 2017-03-28 19:03 ` Kees Cook 2017-03-28 20:31 ` Arnd Bergmann 2017-03-28 20:31 ` Arnd Bergmann 2017-03-28 3:03 ` Andrew Donnellan 2017-03-28 19:00 ` Kees Cook 2017-03-28 19:00 ` Kees Cook 2017-03-29 8:32 ` Arnd Bergmann 2017-03-29 8:32 ` [kernel-hardening] " Arnd Bergmann 2017-03-29 8:56 ` Arnd Bergmann 2017-03-29 8:56 ` [kernel-hardening] " Arnd Bergmann 2017-03-30 11:04 ` Arnd Bergmann 2017-03-30 11:04 ` [kernel-hardening] " Arnd Bergmann 2017-01-31 20:24 ` [PATCH v5 2/4] util: Move type casts into is_kernel_rodata Kees Cook 2017-01-31 20:24 ` [kernel-hardening] " Kees Cook 2017-01-31 20:24 ` [PATCH v5 3/4] initify: Mark functions with the __nocapture attribute Kees Cook 2017-01-31 20:24 ` [kernel-hardening] " Kees Cook 2017-01-31 20:24 ` Kees Cook [this message] 2017-01-31 20:24 ` [kernel-hardening] [PATCH v5 4/4] initify: Mark functions with the __unverified_nocapture attribute Kees Cook
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