[PATCH] Revert "zram: convert remaining CLASS_ATTR() to CLASS_ATTR_RO()"

[PATCH] Revert "zram: convert remaining CLASS_ATTR() to CLASS_ATTR_RO()"

[Greg Kroah-Hartman]

From: Wade Mealing <wmealing@redhat.com>

Turns out that the permissions for 0400 really are what we want here,
otherwise any user can write to this file.

[fixed formatting and made static - gregkh]

Reported-by: Wade Mealing <wmealing@redhat.com>
Cc: stable <stable@vger.kernel.org>
Fixes: f40609d1591f ("zram: convert remaining CLASS_ATTR() to CLASS_ATTR_RO()")
Link: https://bugzilla.redhat.com/show_bug.cgi?id=1847832
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/block/zram/zram_drv.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 6e2ad90b17a3..270dd810be54 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -2021,7 +2021,8 @@ static ssize_t hot_add_show(struct class *class,
 		return ret;
 	return scnprintf(buf, PAGE_SIZE, "%d\n", ret);
 }
-static CLASS_ATTR_RO(hot_add);
+static struct class_attribute class_attr_hot_add =
+	__ATTR(hot_add, 0400, hot_add_show, NULL);
 
 static ssize_t hot_remove_store(struct class *class,
 			struct class_attribute *attr,
-- 
2.27.0

Re: [PATCH] Revert "zram: convert remaining CLASS_ATTR() to CLASS_ATTR_RO()"

[Steffen Maier]

On 6/17/20 12:34 PM, Greg Kroah-Hartman wrote:
> From: Wade Mealing <wmealing@redhat.com>
> 
> Turns out that the permissions for 0400 really are what we want here,
> otherwise any user can write to this file.

Minor confusion on my side:
Did you mean "read from" instead of "write to"?
I.e. only owner may read but not group nor others.
Whereas using CLASS_ATTR_RO would resolve into 0444.

> 
> [fixed formatting and made static - gregkh]
> 
> Reported-by: Wade Mealing <wmealing@redhat.com>
> Cc: stable <stable@vger.kernel.org>
> Fixes: f40609d1591f ("zram: convert remaining CLASS_ATTR() to CLASS_ATTR_RO()")
> Link: https://bugzilla.redhat.com/show_bug.cgi?id=1847832
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
>   drivers/block/zram/zram_drv.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> index 6e2ad90b17a3..270dd810be54 100644
> --- a/drivers/block/zram/zram_drv.c
> +++ b/drivers/block/zram/zram_drv.c
> @@ -2021,7 +2021,8 @@ static ssize_t hot_add_show(struct class *class,
>   		return ret;
>   	return scnprintf(buf, PAGE_SIZE, "%d\n", ret);
>   }
> -static CLASS_ATTR_RO(hot_add);
> +static struct class_attribute class_attr_hot_add =
> +	__ATTR(hot_add, 0400, hot_add_show, NULL);
> 
>   static ssize_t hot_remove_store(struct class *class,
>   			struct class_attribute *attr,
> 


-- 
Mit freundlichen Gruessen / Kind regards
Steffen Maier

Linux on IBM Z Development

https://www.ibm.com/privacy/us/en/
IBM Deutschland Research & Development GmbH
Vorsitzender des Aufsichtsrats: Matthias Hartmann
Geschaeftsfuehrung: Dirk Wittkopp
Sitz der Gesellschaft: Boeblingen
Registergericht: Amtsgericht Stuttgart, HRB 243294

Re: [PATCH] Revert "zram: convert remaining CLASS_ATTR() to CLASS_ATTR_RO()"

[Greg Kroah-Hartman]

On Wed, Jun 17, 2020 at 01:05:54PM +0200, Steffen Maier wrote:
> On 6/17/20 12:34 PM, Greg Kroah-Hartman wrote:
> > From: Wade Mealing <wmealing@redhat.com>
> > 
> > Turns out that the permissions for 0400 really are what we want here,
> > otherwise any user can write to this file.
> 
> Minor confusion on my side:
> Did you mean "read from" instead of "write to"?
> I.e. only owner may read but not group nor others.
> Whereas using CLASS_ATTR_RO would resolve into 0444.

Sorry, you are correct, I'll fix the changelog text and send this out
again.

It's a "fun" file, reading from it causes something to happen, not the
normal way things work :(

greg k-h

[PATCH v2] Revert "zram: convert remaining CLASS_ATTR() to CLASS_ATTR_RO()"

[Greg Kroah-Hartman]

From: Wade Mealing <wmealing@redhat.com>

Turns out that the permissions for 0400 really are what we want here,
otherwise any user can read from this file.

[fixed formatting, added changelog, and made attribute static - gregkh]

Reported-by: Wade Mealing <wmealing@redhat.com>
Cc: stable <stable@vger.kernel.org>
Fixes: f40609d1591f ("zram: convert remaining CLASS_ATTR() to CLASS_ATTR_RO()")
Link: https://bugzilla.redhat.com/show_bug.cgi?id=1847832
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
v2: fix read/write confusion in the changelog, thanks to Steffen for the
    review.
    was more specific as to the changes I made to the original patch.

 drivers/block/zram/zram_drv.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 6e2ad90b17a3..270dd810be54 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -2021,7 +2021,8 @@ static ssize_t hot_add_show(struct class *class,
 		return ret;
 	return scnprintf(buf, PAGE_SIZE, "%d\n", ret);
 }
-static CLASS_ATTR_RO(hot_add);
+static struct class_attribute class_attr_hot_add =
+	__ATTR(hot_add, 0400, hot_add_show, NULL);
 
 static ssize_t hot_remove_store(struct class *class,
 			struct class_attribute *attr,
-- 
2.27.0

Re: [PATCH] Revert "zram: convert remaining CLASS_ATTR() to CLASS_ATTR_RO()"

[Willy Tarreau]

Hi Greg,

On Wed, Jun 17, 2020 at 12:34:12PM +0200, Greg Kroah-Hartman wrote:
> From: Wade Mealing <wmealing@redhat.com>
> 
> Turns out that the permissions for 0400 really are what we want here,
> otherwise any user can write to this file.
                         ^^^^^^^^
s/write to/read from/

As Wade reported, it's sufficient to read from it to create a zram entry.

Regards,
Willy

Re: [PATCH] Revert "zram: convert remaining CLASS_ATTR() to CLASS_ATTR_RO()"

[Willy Tarreau]

On Wed, Jun 17, 2020 at 02:31:00PM +0200, Willy Tarreau wrote:
> Hi Greg,
> 
> On Wed, Jun 17, 2020 at 12:34:12PM +0200, Greg Kroah-Hartman wrote:
> > From: Wade Mealing <wmealing@redhat.com>
> > 
> > Turns out that the permissions for 0400 really are what we want here,
> > otherwise any user can write to this file.
>                          ^^^^^^^^
> s/write to/read from/
> 
> As Wade reported, it's sufficient to read from it to create a zram entry.

Bah I just saw your v2 now, sorry for the noise.

Willy

Re: [PATCH v2] Revert "zram: convert remaining CLASS_ATTR() to CLASS_ATTR_RO()"

[Steffen Maier]

On 6/17/20 1:49 PM, Greg Kroah-Hartman wrote:
> From: Wade Mealing <wmealing@redhat.com>
> 
> Turns out that the permissions for 0400 really are what we want here,
> otherwise any user can read from this file.
> 
> [fixed formatting, added changelog, and made attribute static - gregkh]
> 
> Reported-by: Wade Mealing <wmealing@redhat.com>
> Cc: stable <stable@vger.kernel.org>
> Fixes: f40609d1591f ("zram: convert remaining CLASS_ATTR() to CLASS_ATTR_RO()")
> Link: https://bugzilla.redhat.com/show_bug.cgi?id=1847832
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Reviewed-by: Steffen Maier <maier@linux.ibm.com>

> ---
> v2: fix read/write confusion in the changelog, thanks to Steffen for the
>      review.
>      was more specific as to the changes I made to the original patch.
> 
>   drivers/block/zram/zram_drv.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> index 6e2ad90b17a3..270dd810be54 100644
> --- a/drivers/block/zram/zram_drv.c
> +++ b/drivers/block/zram/zram_drv.c
> @@ -2021,7 +2021,8 @@ static ssize_t hot_add_show(struct class *class,
>   		return ret;
>   	return scnprintf(buf, PAGE_SIZE, "%d\n", ret);
>   }
> -static CLASS_ATTR_RO(hot_add);
> +static struct class_attribute class_attr_hot_add =
> +	__ATTR(hot_add, 0400, hot_add_show, NULL);
>   
>   static ssize_t hot_remove_store(struct class *class,
>   			struct class_attribute *attr,
> 


-- 
Mit freundlichen Gruessen / Kind regards
Steffen Maier

Linux on IBM Z Development

https://www.ibm.com/privacy/us/en/
IBM Deutschland Research & Development GmbH
Vorsitzender des Aufsichtsrats: Matthias Hartmann
Geschaeftsfuehrung: Dirk Wittkopp
Sitz der Gesellschaft: Boeblingen
Registergericht: Amtsgericht Stuttgart, HRB 243294

Re: [PATCH v2] Revert "zram: convert remaining CLASS_ATTR() to CLASS_ATTR_RO()"

[Minchan Kim]

On Wed, Jun 17, 2020 at 01:49:46PM +0200, Greg Kroah-Hartman wrote:
> From: Wade Mealing <wmealing@redhat.com>
> 
> Turns out that the permissions for 0400 really are what we want here,
> otherwise any user can read from this file.
> 
> [fixed formatting, added changelog, and made attribute static - gregkh]
> 
> Reported-by: Wade Mealing <wmealing@redhat.com>
> Cc: stable <stable@vger.kernel.org>
> Fixes: f40609d1591f ("zram: convert remaining CLASS_ATTR() to CLASS_ATTR_RO()")
> Link: https://bugzilla.redhat.com/show_bug.cgi?id=1847832
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Acked-by: Minchan Kim <minchan@kernel.org>