linux-kernel - Re: [PATCH v2 12/25] selinux: add hooks for fscaps operations

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Date: Wed, 21 Feb 2024 18:38:33 -0500
From: Paul Moore <paul@...l-moore.com>
To: "Seth Forshee (DigitalOcean)" <sforshee@...nel.org>
Cc: Christian Brauner <brauner@...nel.org>, Serge Hallyn <serge@...lyn.com>, Eric Paris <eparis@...hat.com>, 
	James Morris <jmorris@...ei.org>, Alexander Viro <viro@...iv.linux.org.uk>, Jan Kara <jack@...e.cz>, 
	Stephen Smalley <stephen.smalley.work@...il.com>, Ondrej Mosnacek <omosnace@...hat.com>, 
	Casey Schaufler <casey@...aufler-ca.com>, Mimi Zohar <zohar@...ux.ibm.com>, 
	Roberto Sassu <roberto.sassu@...wei.com>, Dmitry Kasatkin <dmitry.kasatkin@...il.com>, 
	Eric Snowberg <eric.snowberg@...cle.com>, "Matthew Wilcox (Oracle)" <willy@...radead.org>, 
	Jonathan Corbet <corbet@....net>, Miklos Szeredi <miklos@...redi.hu>, Amir Goldstein <amir73il@...il.com>, 
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org, 
	linux-security-module@...r.kernel.org, audit@...r.kernel.org, 
	selinux@...r.kernel.org, linux-integrity@...r.kernel.org, 
	linux-doc@...r.kernel.org, linux-unionfs@...r.kernel.org
Subject: Re: [PATCH v2 12/25] selinux: add hooks for fscaps operations

On Wed, Feb 21, 2024 at 4:25 PM Seth Forshee (DigitalOcean)
<sforshee@...nel.org> wrote:
>
> Add hooks for set/get/remove fscaps operations which perform the same
> checks as the xattr hooks would have done for XATTR_NAME_CAPS.
>
> Signed-off-by: Seth Forshee (DigitalOcean) <sforshee@...nel.org>
> ---
>  security/selinux/hooks.c | 26 ++++++++++++++++++++++++++
>  1 file changed, 26 insertions(+)
>
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index a6bf90ace84c..da129a387b34 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -3367,6 +3367,29 @@ static int selinux_inode_removexattr(struct mnt_idmap *idmap,
>         return -EACCES;
>  }
>
> +static int selinux_inode_set_fscaps(struct mnt_idmap *idmap,
> +                                   struct dentry *dentry,
> +                                   const struct vfs_caps *caps, int flags)
> +{
> +       return dentry_has_perm(current_cred(), dentry, FILE__SETATTR);
> +}

The selinux_inode_setxattr() code also has a cap_inode_setxattr()
check which is missing here.  Unless you are handling this somewhere
else, I would expect the function above to look similar to
selinux_inode_remove_fscaps(), but obviously tweaked for setting the
fscaps and not removing them.

> +static int selinux_inode_get_fscaps(struct mnt_idmap *idmap,
> +                                   struct dentry *dentry)
> +{
> +       return dentry_has_perm(current_cred(), dentry, FILE__GETATTR);
> +}
> +
> +static int selinux_inode_remove_fscaps(struct mnt_idmap *idmap,
> +                                      struct dentry *dentry)
> +{
> +       int rc = cap_inode_removexattr(idmap, dentry, XATTR_NAME_CAPS);
> +       if (rc)
> +               return rc;
> +
> +       return dentry_has_perm(current_cred(), dentry, FILE__SETATTR);
> +}
> +
>  static int selinux_path_notify(const struct path *path, u64 mask,
>                                                 unsigned int obj_type)
>  {
> @@ -7165,6 +7188,9 @@ static struct security_hook_list selinux_hooks[] __ro_after_init = {
>         LSM_HOOK_INIT(inode_set_acl, selinux_inode_set_acl),
>         LSM_HOOK_INIT(inode_get_acl, selinux_inode_get_acl),
>         LSM_HOOK_INIT(inode_remove_acl, selinux_inode_remove_acl),
> +       LSM_HOOK_INIT(inode_set_fscaps, selinux_inode_set_fscaps),
> +       LSM_HOOK_INIT(inode_get_fscaps, selinux_inode_get_fscaps),
> +       LSM_HOOK_INIT(inode_remove_fscaps, selinux_inode_remove_fscaps),
>         LSM_HOOK_INIT(inode_getsecurity, selinux_inode_getsecurity),
>         LSM_HOOK_INIT(inode_setsecurity, selinux_inode_setsecurity),
>         LSM_HOOK_INIT(inode_listsecurity, selinux_inode_listsecurity),
>
> --
> 2.43.0

-- 
paul-moore.com