From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Wed, 9 Mar 2011 19:52:46 -0300 From: Vinicius Costa Gomes To: linux-bluetooth@vger.kernel.org Subject: Re: [bluetooth-next 04/15] Bluetooth: Add support for using the crypto subsystem Message-ID: <20110309225246.GA3009@piper> References: <02fa778ab4292dffba1330e829b0d4029517a21e.1298307667.git.vinicius.gomes@openbossa.org> <20110227202041.GG2166@joana> <20110228172801.GB2165@joana> <20110303174501.GA10733@piper> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 In-Reply-To: <20110303174501.GA10733@piper> Sender: linux-bluetooth-owner@vger.kernel.org List-ID: On 14:45 Thu 03 Mar, Vinicius Costa Gomes wrote: > Hi Marcel, > > On 14:28 Mon 28 Feb, Gustavo F. Padovan wrote: > > Hi Vinicius, > > > > * Vinicius Gomes [2011-02-27 21:49:39 -0300]: > > > > > Hi Gustavo, > > > > > > On Sun, Feb 27, 2011 at 5:20 PM, Gustavo F. Padovan > > > wrote: > > > > Hi Vinicius, > > > > > > > > * Vinicius Costa Gomes [2011-02-21 14:23:51 -0300]: > > > > > > > >> This will allow using the crypto subsystem for encrypting data. As SMP > > > >> (Security Manager Protocol) is implemented almost entirely on the host > > > >> side and the crypto module already implements the needed methods > > > >> (AES-128), it makes sense to use it. > > > >> > > > >> This patch also adds a new Kconfig option to toggle the SMP support. > > > >> > > > >> Signed-off-by: Vinicius Costa Gomes > > > >> Signed-off-by: Anderson Briglia > > > >> --- > > > >>  include/net/bluetooth/hci_core.h |    2 ++ > > > >>  net/bluetooth/Kconfig            |    6 ++++++ > > > >>  net/bluetooth/hci_core.c         |   22 ++++++++++++++++++++++ > > > >>  net/bluetooth/smp.c              |   17 +++++++++++++++-- > > > >>  4 files changed, 45 insertions(+), 2 deletions(-) > > > >> > > > >> diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h > > > >> index d5d8454..e8dbde8 100644 > > > >> --- a/include/net/bluetooth/hci_core.h > > > >> +++ b/include/net/bluetooth/hci_core.h > > > >> @@ -161,6 +161,8 @@ struct hci_dev { > > > >> > > > >>       __u16                   init_last_cmd; > > > >> > > > >> +     struct crypto_blkcipher *tfm; > > > >> + > > > >>       struct inquiry_cache    inq_cache; > > > >>       struct hci_conn_hash    conn_hash; > > > >>       struct list_head        blacklist; > > > >> diff --git a/net/bluetooth/Kconfig b/net/bluetooth/Kconfig > > > >> index c6f9c2f..e9f40af 100644 > > > >> --- a/net/bluetooth/Kconfig > > > >> +++ b/net/bluetooth/Kconfig > > > >> @@ -22,6 +22,7 @@ menuconfig BT > > > >>            BNEP Module (Bluetooth Network Encapsulation Protocol) > > > >>            CMTP Module (CAPI Message Transport Protocol) > > > >>            HIDP Module (Human Interface Device Protocol) > > > >> +          SMP Module (Security Manager Protocol) > > > >> > > > >>         Say Y here to compile Bluetooth support into the kernel or say M to > > > >>         compile it as module (bluetooth). > > > >> @@ -35,11 +36,16 @@ config BT_L2CAP > > > >>       bool "L2CAP protocol support" > > > >>       depends on BT > > > >>       select CRC16 > > > >> +     select CRYPTO_BLKCIPHER > > > >> +     select CRYPTO_AES > > > >>       help > > > >>         L2CAP (Logical Link Control and Adaptation Protocol) provides > > > >>         connection oriented and connection-less data transport.  L2CAP > > > >>         support is required for most Bluetooth applications. > > > >> > > > >> +       Also included is support for SMP (Security Manager Protocol) which > > > >> +       is the security layer on top of LE (Low Energy) links. > > > >> + > > > >>  config BT_SCO > > > >>       bool "SCO links support" > > > >>       depends on BT > > > >> diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c > > > >> index b372fb8..ff67843 100644 > > > >> --- a/net/bluetooth/hci_core.c > > > >> +++ b/net/bluetooth/hci_core.c > > > >> @@ -42,6 +42,7 @@ > > > >>  #include > > > >>  #include > > > >>  #include > > > >> +#include > > > >>  #include > > > >> > > > >>  #include > > > >> @@ -60,6 +61,8 @@ static void hci_notify(struct hci_dev *hdev, int event); > > > >> > > > >>  static DEFINE_RWLOCK(hci_task_lock); > > > >> > > > >> +static int enable_smp; > > > >> + > > > >>  /* HCI device list */ > > > >>  LIST_HEAD(hci_dev_list); > > > >>  DEFINE_RWLOCK(hci_dev_list_lock); > > > >> @@ -1077,6 +1080,14 @@ static void hci_cmd_timer(unsigned long arg) > > > >>       tasklet_schedule(&hdev->cmd_task); > > > >>  } > > > >> > > > >> +static struct crypto_blkcipher *alloc_cypher(void) > > > >> +{ > > > >> +     if (enable_smp) > > > >> +             return crypto_alloc_blkcipher("ecb(aes)", 0, CRYPTO_ALG_ASYNC); > > > >> + > > > >> +     return ERR_PTR(-ENOTSUPP); > > > >> +} > > > >> + > > > >>  /* Register HCI device */ > > > >>  int hci_register_dev(struct hci_dev *hdev) > > > >>  { > > > >> @@ -1155,6 +1166,11 @@ int hci_register_dev(struct hci_dev *hdev) > > > >>       if (!hdev->workqueue) > > > >>               goto nomem; > > > >> > > > >> +     hdev->tfm = alloc_cypher(); > > > >> +     if (IS_ERR(hdev->tfm)) > > > >> +             BT_INFO("Failed to load transform for ecb(aes): %ld", > > > >> +                                                     PTR_ERR(hdev->tfm)); > > > >> + > > > >>       hci_register_sysfs(hdev); > > > >> > > > >>       hdev->rfkill = rfkill_alloc(hdev->name, &hdev->dev, > > > >> @@ -1203,6 +1219,9 @@ int hci_unregister_dev(struct hci_dev *hdev) > > > >>                                       !test_bit(HCI_SETUP, &hdev->flags)) > > > >>               mgmt_index_removed(hdev->id); > > > >> > > > >> +     if (!IS_ERR(hdev->tfm)) > > > >> +             crypto_free_blkcipher(hdev->tfm); > > > >> + > > > >>       hci_notify(hdev, HCI_DEV_UNREG); > > > >> > > > >>       if (hdev->rfkill) { > > > >> @@ -2037,3 +2056,6 @@ static void hci_cmd_task(unsigned long arg) > > > >>               } > > > >>       } > > > >>  } > > > >> + > > > >> +module_param(enable_smp, bool, 0644); > > > >> +MODULE_PARM_DESC(enable_smp, "Enable SMP support (LE only)"); > > > > > > > > This all should be obviously inside smp.c > > > > > > I have a couple of points against it: > > > > > > 1. it's only used for one purpose, it says whether to try or not to > > > allocate the block cypher, which is done during the adapter > > > registration; > > > > > > 2. If the current way is ok, it would mean that I would need to export > > > another method from smp.c, that was something that I tried to > > > minimize; > > > > > > 3. and my weakest argument, seems that there are other similar uses, > > > for example enable_mgmt. > > > > A similar example here is enable_ertm inside l2cap_core.c. It's a L2CAP > > related option and should reside inside L2CAP code. > > > > > > > > But if you think the code will be clearer moving that to smp.c, will > > > be glad to change. > > > > I don't see the point on have it on hci code. SMP and Block cypher has > > not much to do with HCI. I prefer it on smp.c > > Gustavo and I were talking on IRC and couldn't come to a solution, so > we ask you for some input. > > So, just to give a little more context, the problem is that the crypto > functions used in SMP depend on the allocation of a block cypher "transform", > this allocation must happen during user context. > > The current solution is that the allocation is done in hci_core.c during the > adapter registration, but only when the enable_smp module parameter is enabled. > When the parameter is disabled the allocation method just returns an invalid > pointer and everything happens the same as if the allocation has failed. > > Gustavo has a preference for an ondemand aproach, for example, using a > workqueue for doing the allocation, and trying the allocation just when SMP is > going to be used, e.g. when we receive the first SMP message or when some > security level is activated for that socket. > > Any ideas? Still no ideas? > > > > > -- > > Gustavo F. Padovan > > http://profusion.mobi > > > Cheers, > -- > Vinicius -- Vinicius