From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Biggers Date: Wed, 14 Aug 2019 22:35:43 +0000 Subject: Re: [PATCH v8 10/20] fscrypt: add FS_IOC_REMOVE_ENCRYPTION_KEY ioctl Message-Id: <20190814223542.GE101319@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit List-Id: References: <20190805162521.90882-1-ebiggers@kernel.org> <20190805162521.90882-11-ebiggers@kernel.org> <20190813000644.GH28705@mit.edu> In-Reply-To: <20190813000644.GH28705@mit.edu> To: "Theodore Y. Ts'o" Cc: Satya Tangirala , linux-api@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-fscrypt@vger.kernel.org, keyrings@vger.kernel.org, linux-mtd@lists.infradead.org, linux-crypto@vger.kernel.org, linux-fsdevel@vger.kernel.org, Jaegeuk Kim , linux-ext4@vger.kernel.org, Paul Crowley On Mon, Aug 12, 2019 at 08:06:44PM -0400, Theodore Y. Ts'o wrote: > > + /* Some inodes still reference this key; try to evict them. */ > > + if (try_to_lock_encrypted_files(sb, mk) != 0) > > + status_flags |> > + FSCRYPT_KEY_REMOVAL_STATUS_FLAG_FILES_BUSY; > > + } > > try_to_lock_encrypted_files() can return other errors besides -EBUSY; > in particular sync_filesystem() can return other errors, such as -EIO > or -EFSCORUPTED. In that case, I think we're better off returning the > relevant status code back to the user. We will have already wiped the > master key, but this situation will only happen in exceptional > conditions (e.g., user has ejected the sdcard, etc.), so it's not > worth it to try to undo the master key wipe to try to restore things > to the pre-ioctl execution state. > > So I think we should capture the return code from > try_to_lock_encrypted_files, and if it is EBUSY, we can set FILES_BUSY > flag and return success. Otherwise, we should return the error. > > If you agree, please fix that up and then feel free to add: > > Reviewed-by: Theodore Ts'o > > - Ted Yes, that makes sense. I've made the following change to this patch: diff --git a/fs/crypto/keyring.c b/fs/crypto/keyring.c index 9901593051424b..c3423f0edc7014 100644 --- a/fs/crypto/keyring.c +++ b/fs/crypto/keyring.c @@ -479,6 +479,7 @@ int fscrypt_ioctl_remove_key(struct file *filp, void __user *_uarg) struct key *key; struct fscrypt_master_key *mk; u32 status_flags = 0; + int err; bool dead; if (copy_from_user(&arg, uarg, sizeof(arg))) @@ -514,11 +515,15 @@ int fscrypt_ioctl_remove_key(struct file *filp, void __user *_uarg) * key object is free to be removed from the keyring. */ key_invalidate(key); + err = 0; } else { /* Some inodes still reference this key; try to evict them. */ - if (try_to_lock_encrypted_files(sb, mk) != 0) + err = try_to_lock_encrypted_files(sb, mk); + if (err = -EBUSY) { status_flags | FSCRYPT_KEY_REMOVAL_STATUS_FLAG_FILES_BUSY; + err = 0; + } } /* * We return 0 if we successfully did something: wiped the secret, or @@ -527,7 +532,9 @@ int fscrypt_ioctl_remove_key(struct file *filp, void __user *_uarg) * including all files locked. */ key_put(key); - return put_user(status_flags, &uarg->removal_status_flags); + if (err = 0) + err = put_user(status_flags, &uarg->removal_status_flags); + return err; } EXPORT_SYMBOL_GPL(fscrypt_ioctl_remove_key);