linux-kernel - Re: [PATCH 06/11] ubifs: reorder capability check last

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Message-ID: <1045101183.70157813.1732534258584.JavaMail.zimbra@nod.at>
Date: Mon, 25 Nov 2024 12:30:58 +0100 (CET)
From: Richard Weinberger <richard@....at>
To: cgzones@...glemail.com
Cc: LSM <linux-security-module@...r.kernel.org>, 
	Boris Brezillon <boris.brezillon@...labora.com>, 
	Steven Price <steven.price@....com>, 
	Liviu Dudau <liviu.dudau@....com>, 
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
	Maxime Ripard <mripard@...nel.org>, 
	Thomas Zimmermann <tzimmermann@...e.de>, 
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
	chengzhihao1 <chengzhihao1@...wei.com>, 
	"Serge E. Hallyn" <serge@...lyn.com>, 
	Julia Lawall <Julia.Lawall@...ia.fr>, 
	Nicolas Palix <nicolas.palix@...g.fr>, 
	linux-kernel <linux-kernel@...r.kernel.org>, 
	DRI mailing list <dri-devel@...ts.freedesktop.org>, 
	linux-mtd <linux-mtd@...ts.infradead.org>, cocci <cocci@...ia.fr>
Subject: Re: [PATCH 06/11] ubifs: reorder capability check last

----- Ursprüngliche Mail -----
> Von: "Christian Göttsche" <cgoettsche@...tendoof.de>
> capable() calls refer to enabled LSMs whether to permit or deny the
> request.  This is relevant in connection with SELinux, where a
> capability check results in a policy decision and by default a denial
> message on insufficient permission is issued.
> It can lead to three undesired cases:
>  1. A denial message is generated, even in case the operation was an
>     unprivileged one and thus the syscall succeeded, creating noise.
>  2. To avoid the noise from 1. the policy writer adds a rule to ignore
>     those denial messages, hiding future syscalls, where the task
>     performs an actual privileged operation, leading to hidden limited
>     functionality of that task.
>  3. To avoid the noise from 1. the policy writer adds a rule to permit
>     the task the requested capability, while it does not need it,
>     violating the principle of least privilege.
> 
> Signed-off-by: Christian Göttsche <cgzones@...glemail.com>
> ---
> drivers/gpu/drm/panthor/panthor_drv.c | 2 +-

This change is unrelated, please remove it.

> fs/ubifs/budget.c                     | 5 +++--
> 2 files changed, 4 insertions(+), 3 deletions(-)

[...]

> diff --git a/fs/ubifs/budget.c b/fs/ubifs/budget.c
> index d76eb7b39f56..6137aeadec3f 100644
> --- a/fs/ubifs/budget.c
> +++ b/fs/ubifs/budget.c
> @@ -256,8 +256,9 @@ long long ubifs_calc_available(const struct ubifs_info *c,
> int min_idx_lebs)
>  */
> static int can_use_rp(struct ubifs_info *c)
> {
> -	if (uid_eq(current_fsuid(), c->rp_uid) || capable(CAP_SYS_RESOURCE) ||
> -	    (!gid_eq(c->rp_gid, GLOBAL_ROOT_GID) && in_group_p(c->rp_gid)))
> +	if (uid_eq(current_fsuid(), c->rp_uid) ||
> +	    (!gid_eq(c->rp_gid, GLOBAL_ROOT_GID) && in_group_p(c->rp_gid)) ||
> +	    capable(CAP_SYS_RESOURCE))
> 		return 1;
> 	return 0;
> }

The UBIFS part looks ok:

Acked-by: Richard Weinberger <richard@....at>

Since I was not CC'ed to the whole series, I miss a lot of context.
Will this series merged as a whole? By whom?

Thanks,
//richard