Re: [PATCH v2 2/3] sysfs: Only accept read/write permissions for file attributes
From: Greg Kroah-Hartman
Date: Thu Mar 12 2015 - 09:49:35 EST
On Thu, Mar 12, 2015 at 03:39:04AM -0700, Guenter Roeck wrote:
> On 03/12/2015 03:01 AM, Greg Kroah-Hartman wrote:
> >On Wed, Mar 11, 2015 at 02:22:10PM -0400, Vivien Didelot wrote:
> >>For sysfs file attributes, only read and write permissions make sense.
> >>Mask provided attribute permissions accordingly and send a warning
> >>to the console if invalid permission bits are set.
> >>This patch is originally from Guenter  and includes the fixup
> >>explained in the thread, that is printing permissions in octal format
> >>and limiting the scope of attributes to SYSFS_PREALLOC | 0664.
> >> https://lkml.org/lkml/2015/1/19/599
> >>Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
> >>Signed-off-by: Vivien Didelot <vivien.didelot@xxxxxxxxxxxxxxxxxxxx>
> >> fs/sysfs/group.c | 6 ++++++
> >> 1 file changed, 6 insertions(+)
> >>diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
> >>index 3fdccd9..b400c04 100644
> >>--- a/fs/sysfs/group.c
> >>+++ b/fs/sysfs/group.c
> >>@@ -55,6 +55,12 @@ static int create_files(struct kernfs_node *parent, struct kobject *kobj,
> >> if (!mode)
> >> continue;
> >> }
> >>+ WARN(mode & ~(SYSFS_PREALLOC | 0664),
> >>+ "Attribute %s: Invalid permissions 0%o\n",
> >>+ (*attr)->name, mode);
> >>+ mode &= SYSFS_PREALLOC | 0664;
> >How does a "normal" boot look with this warning in place? There still
> >seem to be a number of files in sysfs that might trigger this.
> I was under the impression that they all were addressed, but I may have
> missed some pattern(s). Can you point me to an example, by any chance ?
Ah, nevermind, they seem to have all been fixed up.
> >Also, we have a build-time warning if a sysfs file is this type of
> >attribute, shouldn't we just rely on that instead of this run-time
> The mode value can be returned from an is_visible function, and even if not
> there is no guarantee that the build-time warning triggers (attribute lists
> can be generated manually, for example).
You are correct, sorry, I missed that, nevermind again. Once Vivien
fixes up the signed-off-by stuff here, I'll be glad to queue them up.
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