From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 75454145343; Tue, 27 Feb 2024 14:57:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709045872; cv=none; b=QrcgrKWhHO/FCgxbhaFyJXx2XewJv/JaA0FIEJNawqYimE5M6YwwpUCSLDI5tEo0wUM3u8iZMsxeepepVDKM5cL8iAIE2g59IK2FaRObYnPSv2F3hIJ9P6TCVq8XbScvDg8B2tou3UaKGsWmBqtM+Ix7ejxusJBg9IBX4SCwbfs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709045872; c=relaxed/simple; bh=wmEclif75z08Y7k+kYIcq9r8njHDzniHYzsVWuX5qXc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=nvcEbAN/CYonehRsQzbHPhoEnmFJbVdD71rxtQpTCDz1+LJmal3gxNKQUcW772uVU+78sxbhiBDrvW4ovnhLIqIMUnLFZGCk4nJJzSYjMT4FSeuSoLRY8RTDC/vP7liQk2qd9l1+9nNXNvwzEMLmC4CHOTFaYeGwwn4ci4ruHxM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=tsXgDuZq; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="tsXgDuZq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2BB6BC433F1; Tue, 27 Feb 2024 14:57:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1709045872; bh=wmEclif75z08Y7k+kYIcq9r8njHDzniHYzsVWuX5qXc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=tsXgDuZqZaxkgTGkVT4vgZZkifzs/XhauPG/Z8VblgKg3JYBuzgPCH2sN/AOfYAsz Cizp02wJoy2Js13JQt0E+Zl0HHvCGA3oZPWP9ioF8VBtoICsQTFvdJzNjP0YHkL+jx ZIEk0/YHOPTJNdkd9MEZU1P/jrlu9PFKFSfTKXyWBhplucxucznwgrqof5c5iGRM/2 tUKDL8CJyGhfVnM/DYhRi1QnqmdGaigiZHrlvcPEAFN5h7QksWvunvY47bRRJDFmc2 IfgbTjgpxKGsD+8Gs+Bdb72wnC6/I2S3F3cVc+DfaWBszVKJLxEdYDxu+6MSCu1WCQ xKCvkJWQbWn0Q== Date: Tue, 27 Feb 2024 08:57:51 -0600 From: "Seth Forshee (DigitalOcean)" To: Amir Goldstein Cc: Christian Brauner , Serge Hallyn , Paul Moore , Eric Paris , James Morris , Alexander Viro , Jan Kara , Stephen Smalley , Ondrej Mosnacek , Casey Schaufler , Mimi Zohar , Roberto Sassu , Dmitry Kasatkin , Eric Snowberg , "Matthew Wilcox (Oracle)" , Jonathan Corbet , Miklos Szeredi , 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 20/25] ovl: add fscaps handlers Message-ID: References: <20240221-idmap-fscap-refactor-v2-0-3039364623bd@kernel.org> <20240221-idmap-fscap-refactor-v2-20-3039364623bd@kernel.org> Precedence: bulk X-Mailing-List: linux-integrity@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Tue, Feb 27, 2024 at 03:28:18PM +0200, Amir Goldstein wrote: > > +int ovl_set_fscaps(struct mnt_idmap *idmap, struct dentry *dentry, > > + const struct vfs_caps *caps, int setxattr_flags) > > +{ > > + int err; > > + struct ovl_fs *ofs = OVL_FS(dentry->d_sb); > > + struct dentry *upperdentry = ovl_dentry_upper(dentry); > > + struct dentry *realdentry = upperdentry ?: ovl_dentry_lower(dentry); > > + const struct cred *old_cred; > > + > > + /* > > + * If the fscaps are to be remove from a lower file, check that they > > + * exist before copying up. > > + */ > > Don't you need to convert -ENODATA to 0 return value in this case? Do you mean that trying to remove an xattr that does not exist should return 0? Standard behavior is to return -ENODATA in this situation. > > > + if (!caps && !upperdentry) { > > + struct path realpath; > > + struct vfs_caps lower_caps; > > + > > + ovl_path_lower(dentry, &realpath); > > + old_cred = ovl_override_creds(dentry->d_sb); > > + err = vfs_get_fscaps(mnt_idmap(realpath.mnt), realdentry, > > + &lower_caps); > > + revert_creds(old_cred); > > + if (err) > > + goto out; > > + } > > + > > + err = ovl_want_write(dentry); > > + if (err) > > + goto out; > > + > > ovl_want_write() should after ovl_copy_up(), see: > 162d06444070 ("ovl: reorder ovl_want_write() after ovl_inode_lock()") Fixed. > > @@ -758,6 +826,8 @@ static const struct inode_operations ovl_symlink_inode_operations = { > > .get_link = ovl_get_link, > > .getattr = ovl_getattr, > > .listxattr = ovl_listxattr, > > + .get_fscaps = ovl_get_fscaps, > > + .set_fscaps = ovl_set_fscaps, > > .update_time = ovl_update_time, > > }; > > > > @@ -769,6 +839,8 @@ static const struct inode_operations ovl_special_inode_operations = { > > .get_inode_acl = ovl_get_inode_acl, > > .get_acl = ovl_get_acl, > > .set_acl = ovl_set_acl, > > + .get_fscaps = ovl_get_fscaps, > > + .set_fscaps = ovl_set_fscaps, > > .update_time = ovl_update_time, > > }; > > > > > Sorry, I did not understand the explanation why fscaps ops are needed > for non regular files. It does not look right to me. The kernel does not forbid XATTR_NAME_CAPS for non-regular files and will internally even try to read them from non-regular files during killpriv checks. If we do not add handlers then we will end up using the normal ovl xattr handlers, which call vfs_*xattr(). These will return an error for fscaps xattrs after this series, which would be a change in behavior for overlayfs and make it behave differently from other filesystems.