[PATCH v2] mm/zpool: use prefixed module loading

[PATCH v2] mm/zpool: use prefixed module loading

[Kees Cook]

To avoid potential format string expansion via module parameters,
do not use the zpool type directly in request_module() without a
format string. Additionally, to avoid arbitrary modules being loaded
via zpool API (e.g. via the zswap_zpool_type module parameter) add a
"zpool-" prefix to the requested module, as well as module aliases for
the existing zpool types (zbud and zsmalloc).

Signed-off-by: Kees Cook <keescook@chromium.org>
---
v2:
- moved module aliases into ifdefs (ddstreet)
---
 mm/zbud.c     | 1 +
 mm/zpool.c    | 2 +-
 mm/zsmalloc.c | 1 +
 3 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/mm/zbud.c b/mm/zbud.c
index a05790b1915e..f26e7fcc7fa2 100644
--- a/mm/zbud.c
+++ b/mm/zbud.c
@@ -195,6 +195,7 @@ static struct zpool_driver zbud_zpool_driver = {
 	.total_size =	zbud_zpool_total_size,
 };
 
+MODULE_ALIAS("zpool-zbud");
 #endif /* CONFIG_ZPOOL */
 
 /*****************
diff --git a/mm/zpool.c b/mm/zpool.c
index e40612a1df00..739cdf0d183a 100644
--- a/mm/zpool.c
+++ b/mm/zpool.c
@@ -150,7 +150,7 @@ struct zpool *zpool_create_pool(char *type, gfp_t gfp, struct zpool_ops *ops)
 	driver = zpool_get_driver(type);
 
 	if (!driver) {
-		request_module(type);
+		request_module("zpool-%s", type);
 		driver = zpool_get_driver(type);
 	}
 
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 4e2fc83cb394..94f38fac5e81 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -315,6 +315,7 @@ static struct zpool_driver zs_zpool_driver = {
 	.total_size =	zs_zpool_total_size,
 };
 
+MODULE_ALIAS("zpool-zsmalloc");
 #endif /* CONFIG_ZPOOL */
 
 /* per-cpu VM mapping areas for zspage accesses that cross page boundaries */
-- 
1.9.1


-- 
Kees Cook
Chrome OS Security

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Re: [PATCH v2] mm/zpool: use prefixed module loading

[Dan Streetman]

On Tue, Aug 12, 2014 at 3:06 PM, Kees Cook <keescook@chromium.org> wrote:
> To avoid potential format string expansion via module parameters,
> do not use the zpool type directly in request_module() without a
> format string. Additionally, to avoid arbitrary modules being loaded
> via zpool API (e.g. via the zswap_zpool_type module parameter) add a
> "zpool-" prefix to the requested module, as well as module aliases for
> the existing zpool types (zbud and zsmalloc).

Looks good and tested ok.  Thanks!

Acked-by: Dan Streetman <ddstreet@ieee.org>

>
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
> v2:
> - moved module aliases into ifdefs (ddstreet)
> ---
>  mm/zbud.c     | 1 +
>  mm/zpool.c    | 2 +-
>  mm/zsmalloc.c | 1 +
>  3 files changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/mm/zbud.c b/mm/zbud.c
> index a05790b1915e..f26e7fcc7fa2 100644
> --- a/mm/zbud.c
> +++ b/mm/zbud.c
> @@ -195,6 +195,7 @@ static struct zpool_driver zbud_zpool_driver = {
>         .total_size =   zbud_zpool_total_size,
>  };
>
> +MODULE_ALIAS("zpool-zbud");
>  #endif /* CONFIG_ZPOOL */
>
>  /*****************
> diff --git a/mm/zpool.c b/mm/zpool.c
> index e40612a1df00..739cdf0d183a 100644
> --- a/mm/zpool.c
> +++ b/mm/zpool.c
> @@ -150,7 +150,7 @@ struct zpool *zpool_create_pool(char *type, gfp_t gfp, struct zpool_ops *ops)
>         driver = zpool_get_driver(type);
>
>         if (!driver) {
> -               request_module(type);
> +               request_module("zpool-%s", type);
>                 driver = zpool_get_driver(type);
>         }
>
> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
> index 4e2fc83cb394..94f38fac5e81 100644
> --- a/mm/zsmalloc.c
> +++ b/mm/zsmalloc.c
> @@ -315,6 +315,7 @@ static struct zpool_driver zs_zpool_driver = {
>         .total_size =   zs_zpool_total_size,
>  };
>
> +MODULE_ALIAS("zpool-zsmalloc");
>  #endif /* CONFIG_ZPOOL */
>
>  /* per-cpu VM mapping areas for zspage accesses that cross page boundaries */
> --
> 1.9.1
>
>
> --
> Kees Cook
> Chrome OS Security
>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@kvack.org.  For more info on Linux MM,
> see: http://www.linux-mm.org/ .
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