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Date: Thu, 22 Feb 2024 16:22:44 +0100
From: Christian Brauner <brauner@kernel.org>
To: "Seth Forshee (DigitalOcean)" <sforshee@kernel.org>
Cc: Serge Hallyn <serge@hallyn.com>, Paul Moore <paul@paul-moore.com>, 
	Eric Paris <eparis@redhat.com>, James Morris <jmorris@namei.org>, 
	Alexander Viro <viro@zeniv.linux.org.uk>, Jan Kara <jack@suse.cz>, 
	Stephen Smalley <stephen.smalley.work@gmail.com>, Ondrej Mosnacek <omosnace@redhat.com>, 
	Casey Schaufler <casey@schaufler-ca.com>, Mimi Zohar <zohar@linux.ibm.com>, 
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	Eric Snowberg <eric.snowberg@oracle.com>, "Matthew Wilcox (Oracle)" <willy@infradead.org>, 
	Jonathan Corbet <corbet@lwn.net>, Miklos Szeredi <miklos@szeredi.hu>, 
	Amir Goldstein <amir73il@gmail.com>, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, 
	linux-security-module@vger.kernel.org, audit@vger.kernel.org, selinux@vger.kernel.org, 
	linux-integrity@vger.kernel.org, linux-doc@vger.kernel.org, linux-unionfs@vger.kernel.org
Subject: Re: [PATCH v2 07/25] capability: provide a helper for converting
 vfs_caps to xattr for userspace
Message-ID: <20240222-amortisieren-geblendet-6e977e2d572c@brauner>
References: <20240221-idmap-fscap-refactor-v2-0-3039364623bd@kernel.org>
 <20240221-idmap-fscap-refactor-v2-7-3039364623bd@kernel.org>
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In-Reply-To: <20240221-idmap-fscap-refactor-v2-7-3039364623bd@kernel.org>

On Wed, Feb 21, 2024 at 03:24:38PM -0600, Seth Forshee (DigitalOcean) wrote:
> cap_inode_getsecurity() implements a handful of policies for capability
> xattrs read by userspace:
> 
>  - It returns EINVAL if the on-disk capability is in v1 format.
> 
>  - It masks off all bits in magic_etc except for the version and
>    VFS_CAP_FLAGS_EFFECTIVE.
> 
>  - v3 capabilities are converted to v2 format if the rootid returned to
>    userspace would be 0 or if the rootid corresponds to root in an
>    ancestor user namespace.
> 
>  - It returns EOVERFLOW for a v3 capability whose rootid does not map to
>    a valid id in current_user_ns() or to root in an ancestor namespace.
> 
> These policies must be maintained when converting vfs_caps to an xattr
> for userspace. Provide a vfs_caps_to_user_xattr() helper which will
> enforce these policies.
> 
> Signed-off-by: Seth Forshee (DigitalOcean) <sforshee@kernel.org>
> ---

Looks good,
Reviewed-by: Christian Brauner <brauner@kernel.org>