[Buildroot] [PATCH] implement granular choice for stack protector
Yann E. MORIN
yann.morin.1998 at free.fr
Sat Dec 26 23:46:35 UTC 2015
Steven, All,
On 2015-03-18 14:46 -0700, Steven Noonan spake thusly:
> This allows us to choose between the varying degrees of stack-smashing
> protection. The differences are documented in the GCC online documentation[1].
> The -fstack-protector-full option tends to be far too aggressive and have too
> much of an impact on performance to be worth doing.
>
> [1] https://gcc.gnu.org/onlinedocs/gcc-4.9.2/gcc/Optimize-Options.html
> Signed-off-by: Steven Noonan <steven at uplinklabs.net>
I've sent an updated version of this patch:
https://patchwork.ozlabs.org/patch/561125/
Thanks! :-)
Regards,
Yann E. MORIN.
> ---
> Config.in | 42 ++++++++++++++++++++++++++++++++++++++----
> package/Makefile.in | 10 +++++++++-
> package/gcc/Config.in.host | 4 ++++
> 3 files changed, 51 insertions(+), 5 deletions(-)
>
> diff --git a/Config.in b/Config.in
> index 2b39d6a..0006e37 100644
> --- a/Config.in
> +++ b/Config.in
> @@ -506,12 +506,13 @@ config BR2_GOOGLE_BREAKPAD_INCLUDE_FILES
>
> endif
>
> -config BR2_ENABLE_SSP
> +choice
> bool "build code with Stack Smashing Protection"
> - depends on BR2_TOOLCHAIN_HAS_SSP
> + default BR2_SSP_STRONG if BR2_TOOLCHAIN_HAS_SSP_STRONG
> + default BR2_SSP_REGULAR
> help
> - Enable stack smashing protection support using GCCs
> - -fstack-protector-all option.
> + Enable stack smashing protection support using GCC's
> + -fstack-protector option family.
>
> See http://www.linuxfromscratch.org/hints/downloads/files/ssp.txt
> for details.
> @@ -520,6 +521,39 @@ config BR2_ENABLE_SSP
> support. This is always the case for glibc and eglibc
> toolchain, but is optional in uClibc toolchains.
>
> +config BR2_SSP_NONE
> + bool "None"
> + help
> + Disable stack-smashing protection.
> +
> +config BR2_SSP_REGULAR
> + bool "-fstack-protector"
> + depends on BR2_TOOLCHAIN_HAS_SSP
> + help
> + Emit extra code to check for buffer overflows, such as stack smashing
> + attacks. This is done by adding a guard variable to functions with
> + vulnerable objects. This includes functions that call alloca, and
> + functions with buffers larger than 8 bytes. The guards are initialized
> + when a function is entered and then checked when the function exits. If
> + a guard check fails, an error message is printed and the program exits.
> +
> +config BR2_SSP_STRONG
> + bool "-fstack-protector-strong"
> + depends on BR2_TOOLCHAIN_HAS_SSP
> + depends on BR2_TOOLCHAIN_HAS_SSP_STRONG
> + help
> + Like -fstack-protector but includes additional functions to be protected
> + — those that have local array definitions, or have references to local
> + frame addresses.
> +
> +config BR2_SSP_ALL
> + bool "-fstack-protector-all"
> + depends on BR2_TOOLCHAIN_HAS_SSP
> + help
> + Like -fstack-protector except that all functions are protected.
> +
> +endchoice
> +
> comment "enabling Stack Smashing Protection requires support in the toolchain"
> depends on !BR2_TOOLCHAIN_HAS_SSP
>
> diff --git a/package/Makefile.in b/package/Makefile.in
> index 803b162..68dc329 100644
> --- a/package/Makefile.in
> +++ b/package/Makefile.in
> @@ -163,7 +163,15 @@ TARGET_CFLAGS += -msep-data
> TARGET_CXXFLAGS += -msep-data
> endif
>
> -ifeq ($(BR2_ENABLE_SSP),y)
> +ifeq ($(BR2_SSP_REGULAR),y)
> +TARGET_CFLAGS += -fstack-protector
> +TARGET_CXXFLAGS += -fstack-protector
> +endif
> +ifeq ($(BR2_SSP_STRONG),y)
> +TARGET_CFLAGS += -fstack-protector-strong
> +TARGET_CXXFLAGS += -fstack-protector-strong
> +endif
> +ifeq ($(BR2_SSP_ALL),y)
> TARGET_CFLAGS += -fstack-protector-all
> TARGET_CXXFLAGS += -fstack-protector-all
> endif
> diff --git a/package/gcc/Config.in.host b/package/gcc/Config.in.host
> index 1a5281c..410bf35 100644
> --- a/package/gcc/Config.in.host
> +++ b/package/gcc/Config.in.host
> @@ -6,6 +6,9 @@ config BR2_GCC_NEEDS_MPC
> config BR2_GCC_SUPPORTS_GRAPHITE
> bool
>
> +config BR2_TOOLCHAIN_HAS_SSP_STRONG
> + bool
> +
> choice
> prompt "GCC compiler Version"
> default BR2_GCC_VERSION_4_8_ARC if BR2_arc
> @@ -77,6 +80,7 @@ choice
> # PR60102 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60102
> select BR2_GCC_NEEDS_MPC
> select BR2_GCC_SUPPORTS_GRAPHITE
> + select BR2_TOOLCHAIN_HAS_SSP_STRONG
>
> endchoice
>
> --
> 2.3.3
>
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