* [PATCH] modules: always page-align module section allocations
@ 2019-07-24 15:01 Jessica Yu
2019-07-25 7:08 ` Bartosz Golaszewski
2019-07-30 8:42 ` Jessica Yu
0 siblings, 2 replies; 3+ messages in thread
From: Jessica Yu @ 2019-07-24 15:01 UTC (permalink / raw)
To: linux-kernel
Cc: Bartosz Golaszewski, Yang Yingliang, Jian Cheng, Nadav Amit,
Sekhar Nori, Kevin Hilman, David Lechner, Adam Ford,
Martin Kaiser, Jessica Yu
Some arches (e.g., arm64, x86) have moved towards non-executable
module_alloc() allocations for security hardening reasons. That means
that the module loader will need to set the text section of a module to
executable, regardless of whether or not CONFIG_STRICT_MODULE_RWX is set.
When CONFIG_STRICT_MODULE_RWX=y, module section allocations are always
page-aligned to handle memory rwx permissions. On some arches with
CONFIG_STRICT_MODULE_RWX=n however, when setting the module text to
executable, the BUG_ON() in frob_text() gets triggered since module
section allocations are not page-aligned when CONFIG_STRICT_MODULE_RWX=n.
Since the set_memory_* API works with pages, and since we need to call
set_memory_x() regardless of whether CONFIG_STRICT_MODULE_RWX is set, we
might as well page-align all module section allocations for ease of
managing rwx permissions of module sections (text, rodata, etc).
Fixes: 2eef1399a866 ("modules: fix BUG when load module with rodata=n")
Reported-by: Martin Kaiser <lists@kaiser.cx>
Reported-by: Bartosz Golaszewski <brgl@bgdev.pl>
Tested-by: David Lechner <david@lechnology.com>
Tested-by: Martin Kaiser <martin@kaiser.cx>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
---
kernel/module.c | 7 +------
1 file changed, 1 insertion(+), 6 deletions(-)
diff --git a/kernel/module.c b/kernel/module.c
index 5933395af9a0..cd8df516666d 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -64,14 +64,9 @@
/*
* Modules' sections will be aligned on page boundaries
- * to ensure complete separation of code and data, but
- * only when CONFIG_STRICT_MODULE_RWX=y
+ * to ensure complete separation of code and data
*/
-#ifdef CONFIG_STRICT_MODULE_RWX
# define debug_align(X) ALIGN(X, PAGE_SIZE)
-#else
-# define debug_align(X) (X)
-#endif
/* If this is set, the section belongs in the init part of the module */
#define INIT_OFFSET_MASK (1UL << (BITS_PER_LONG-1))
--
2.16.4
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] modules: always page-align module section allocations
2019-07-24 15:01 [PATCH] modules: always page-align module section allocations Jessica Yu
@ 2019-07-25 7:08 ` Bartosz Golaszewski
2019-07-30 8:42 ` Jessica Yu
1 sibling, 0 replies; 3+ messages in thread
From: Bartosz Golaszewski @ 2019-07-25 7:08 UTC (permalink / raw)
To: Jessica Yu
Cc: Linux Kernel Mailing List, Yang Yingliang, Jian Cheng,
Nadav Amit, Sekhar Nori, Kevin Hilman, David Lechner, Adam Ford,
Martin Kaiser
śr., 24 lip 2019 o 17:02 Jessica Yu <jeyu@kernel.org> napisał(a):
>
> Some arches (e.g., arm64, x86) have moved towards non-executable
> module_alloc() allocations for security hardening reasons. That means
> that the module loader will need to set the text section of a module to
> executable, regardless of whether or not CONFIG_STRICT_MODULE_RWX is set.
>
> When CONFIG_STRICT_MODULE_RWX=y, module section allocations are always
> page-aligned to handle memory rwx permissions. On some arches with
> CONFIG_STRICT_MODULE_RWX=n however, when setting the module text to
> executable, the BUG_ON() in frob_text() gets triggered since module
> section allocations are not page-aligned when CONFIG_STRICT_MODULE_RWX=n.
> Since the set_memory_* API works with pages, and since we need to call
> set_memory_x() regardless of whether CONFIG_STRICT_MODULE_RWX is set, we
> might as well page-align all module section allocations for ease of
> managing rwx permissions of module sections (text, rodata, etc).
>
> Fixes: 2eef1399a866 ("modules: fix BUG when load module with rodata=n")
> Reported-by: Martin Kaiser <lists@kaiser.cx>
> Reported-by: Bartosz Golaszewski <brgl@bgdev.pl>
> Tested-by: David Lechner <david@lechnology.com>
> Tested-by: Martin Kaiser <martin@kaiser.cx>
> Signed-off-by: Jessica Yu <jeyu@kernel.org>
> ---
> kernel/module.c | 7 +------
> 1 file changed, 1 insertion(+), 6 deletions(-)
>
> diff --git a/kernel/module.c b/kernel/module.c
> index 5933395af9a0..cd8df516666d 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -64,14 +64,9 @@
>
> /*
> * Modules' sections will be aligned on page boundaries
> - * to ensure complete separation of code and data, but
> - * only when CONFIG_STRICT_MODULE_RWX=y
> + * to ensure complete separation of code and data
> */
> -#ifdef CONFIG_STRICT_MODULE_RWX
> # define debug_align(X) ALIGN(X, PAGE_SIZE)
> -#else
> -# define debug_align(X) (X)
> -#endif
>
> /* If this is set, the section belongs in the init part of the module */
> #define INIT_OFFSET_MASK (1UL << (BITS_PER_LONG-1))
> --
> 2.16.4
>
Tested-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] modules: always page-align module section allocations
2019-07-24 15:01 [PATCH] modules: always page-align module section allocations Jessica Yu
2019-07-25 7:08 ` Bartosz Golaszewski
@ 2019-07-30 8:42 ` Jessica Yu
1 sibling, 0 replies; 3+ messages in thread
From: Jessica Yu @ 2019-07-30 8:42 UTC (permalink / raw)
To: linux-kernel
Cc: Bartosz Golaszewski, Yang Yingliang, Jian Cheng, Nadav Amit,
Sekhar Nori, Kevin Hilman, David Lechner, Adam Ford,
Martin Kaiser
+++ Jessica Yu [24/07/19 17:01 +0200]:
>Some arches (e.g., arm64, x86) have moved towards non-executable
>module_alloc() allocations for security hardening reasons. That means
>that the module loader will need to set the text section of a module to
>executable, regardless of whether or not CONFIG_STRICT_MODULE_RWX is set.
>
>When CONFIG_STRICT_MODULE_RWX=y, module section allocations are always
>page-aligned to handle memory rwx permissions. On some arches with
>CONFIG_STRICT_MODULE_RWX=n however, when setting the module text to
>executable, the BUG_ON() in frob_text() gets triggered since module
>section allocations are not page-aligned when CONFIG_STRICT_MODULE_RWX=n.
>Since the set_memory_* API works with pages, and since we need to call
>set_memory_x() regardless of whether CONFIG_STRICT_MODULE_RWX is set, we
>might as well page-align all module section allocations for ease of
>managing rwx permissions of module sections (text, rodata, etc).
>
>Fixes: 2eef1399a866 ("modules: fix BUG when load module with rodata=n")
>Reported-by: Martin Kaiser <lists@kaiser.cx>
>Reported-by: Bartosz Golaszewski <brgl@bgdev.pl>
>Tested-by: David Lechner <david@lechnology.com>
>Tested-by: Martin Kaiser <martin@kaiser.cx>
>Signed-off-by: Jessica Yu <jeyu@kernel.org>
Applied, thanks everyone for testing.
> kernel/module.c | 7 +------
> 1 file changed, 1 insertion(+), 6 deletions(-)
>
>diff --git a/kernel/module.c b/kernel/module.c
>index 5933395af9a0..cd8df516666d 100644
>--- a/kernel/module.c
>+++ b/kernel/module.c
>@@ -64,14 +64,9 @@
>
> /*
> * Modules' sections will be aligned on page boundaries
>- * to ensure complete separation of code and data, but
>- * only when CONFIG_STRICT_MODULE_RWX=y
>+ * to ensure complete separation of code and data
> */
>-#ifdef CONFIG_STRICT_MODULE_RWX
> # define debug_align(X) ALIGN(X, PAGE_SIZE)
>-#else
>-# define debug_align(X) (X)
>-#endif
>
> /* If this is set, the section belongs in the init part of the module */
> #define INIT_OFFSET_MASK (1UL << (BITS_PER_LONG-1))
>--
>2.16.4
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2019-07-24 15:01 [PATCH] modules: always page-align module section allocations Jessica Yu
2019-07-25 7:08 ` Bartosz Golaszewski
2019-07-30 8:42 ` Jessica Yu
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