From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Biggers Subject: [RFC PATCH v2 04/20] fs: add ->s_master_keys to struct super_block Date: Mon, 11 Feb 2019 09:27:22 -0800 Message-ID: <20190211172738.4633-5-ebiggers@kernel.org> References: <20190211172738.4633-1-ebiggers@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from [172.30.20.202] (helo=mx.sourceforge.net) by sfs-ml-2.v29.lw.sourceforge.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from ) id 1gtFOx-0003xI-66 for linux-f2fs-devel@lists.sourceforge.net; Mon, 11 Feb 2019 17:29:51 +0000 Received: from mail.kernel.org ([198.145.29.99]) by sfi-mx-1.v28.lw.sourceforge.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) id 1gtFOq-008MnZ-4D for linux-f2fs-devel@lists.sourceforge.net; Mon, 11 Feb 2019 17:29:50 +0000 In-Reply-To: <20190211172738.4633-1-ebiggers@kernel.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net To: linux-fscrypt@vger.kernel.org Cc: Satya Tangirala , linux-api@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, keyrings@vger.kernel.org, linux-mtd@lists.infradead.org, linux-crypto@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, Paul Crowley From: Eric Biggers Add an ->s_master_keys keyring to 'struct super_block'. New fscrypt ioctls will allow adding and removing encryption keys from this keyring. This will enable solving multiple interrelated problems with how fscrypt keys are provided and managed currently, including: - Making the key status (which is currently per-process) match the filesystem-level status of which encrypted files are "unlocked". - Supporting a proper API to remove encryption keys, "locking" the corresponding encrypted files. - Caching an HMAC transform for each master key, allowing the use of HKDF while still retaining good performance. - Preventing denial of service via keyctl_invalidate(). Similar to the existing ->s_cop, the keyring is added to the VFS-level superblock struct rather than separately to the ext4, f2fs, and ubifs superblock structs so that it can be used by the shared code in fs/crypto/. To minimize overhead, the keyring will only be allocated if userspace actually adds a key; otherwise will stay NULL. Signed-off-by: Eric Biggers --- fs/super.c | 3 +++ include/linux/fs.h | 1 + 2 files changed, 4 insertions(+) diff --git a/fs/super.c b/fs/super.c index 48e25eba8465..7ca05dda905c 100644 --- a/fs/super.c +++ b/fs/super.c @@ -291,6 +291,9 @@ static void __put_super(struct super_block *s) security_sb_free(s); put_user_ns(s->s_user_ns); kfree(s->s_subtype); +#ifdef CONFIG_FS_ENCRYPTION + key_put(s->s_master_keys); +#endif call_rcu(&s->rcu, destroy_super_rcu); } } diff --git a/include/linux/fs.h b/include/linux/fs.h index ba7889bb9ef6..70d929ac89f9 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1405,6 +1405,7 @@ struct super_block { const struct xattr_handler **s_xattr; #ifdef CONFIG_FS_ENCRYPTION const struct fscrypt_operations *s_cop; + struct key *s_master_keys; /* master crypto keys in use */ #endif struct hlist_bl_head s_roots; /* alternate root dentries for NFS */ struct list_head s_mounts; /* list of mounts; _not_ for fs use */ -- 2.20.1