From patchwork Mon Oct 28 07:20:26 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Satya Tangirala X-Patchwork-Id: 11214731 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 30EF01864 for ; Mon, 28 Oct 2019 07:20:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 03A94214AF for ; Mon, 28 Oct 2019 07:20:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="vme0M9e2" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732728AbfJ1HUs (ORCPT ); Mon, 28 Oct 2019 03:20:48 -0400 Received: from mail-vk1-f201.google.com ([209.85.221.201]:48502 "EHLO mail-vk1-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732717AbfJ1HUr (ORCPT ); Mon, 28 Oct 2019 03:20:47 -0400 Received: by mail-vk1-f201.google.com with SMTP id x65so65883vkd.15 for ; Mon, 28 Oct 2019 00:20:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=DgGE3grzIR+GN9HpNoFt3dVePJK0s47e9C+4g0N4hMM=; b=vme0M9e2HPjPQfjoNRvttQYlxaJCaP9HGOtC/nL4M8V4a29QdIJZdI+LJb0Pw2p/Jr LdGcC8Pg85XyuegAA0MAN6H8gcMguNT3nmmlY8OYxM2EaylGl1E/8392CDSl46SucpUQ MFHInTTv7ehTtKoXdn7epuWth4QzBB9bh3N/TA0MsYQLBVyH6FtpnMq2POapzz59C5v3 1UU/B2U2jFBhMKrXXwKalTpfw3QxoeQPHxBYzWv14b852NB8VtWtBtvaA39BQjvJLtla pdCR5OZ3SA7amSjbb1JZmSS15u8pAPRK2LF1UWyXcspI4pkE9NHX5K90hOmoiZOf1NzO YvZg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=DgGE3grzIR+GN9HpNoFt3dVePJK0s47e9C+4g0N4hMM=; b=Fv+nmaLHDhVbqkGjWuy4viierMwcZUMdQtjOj8aXPAuo6BKhcM+BYrKvtwPOvjlwCg YZmZM9I3pG15dzJK3YW1wrJXsQshb02zYa5+7j4MocGosKkDZl4frqgJBX/W6zRBMVKW MI2wmV5cCsJdD0N/dcna/Nn80A02mPDPIwNMXVa1Du5yDHhXUF+B8MddHrRTcE3rR6LI jhE9Ntd6W4xuxCvrhsFd2vgiFq1Xy3EMfu26mjXEd4ZYHkRJaOW2MkvxomsANage77PV yaS2uhAjgvtV3wiNlhQV+IygiGXOEP06rOpCfpD+EJreFUnX/ka3NkD2DZwbK8uw/hA1 iW3A== X-Gm-Message-State: APjAAAX7smF93utvaDGIaZKvANyan2bhOV+pkf54pMqu+tjvcPkiMahs iAImyx5HxPoulB1kQR7XwwI5VOW7gqs= X-Google-Smtp-Source: APXvYqykhnZtdzORXAyupuWqn2BHYQR0B89sobdNSzCHzKD3cGNpudvmnJ9oAl+4yIGw4UNa5Frr46oMdig= X-Received: by 2002:ab0:5a95:: with SMTP id w21mr4781080uae.72.1572247245620; Mon, 28 Oct 2019 00:20:45 -0700 (PDT) Date: Mon, 28 Oct 2019 00:20:26 -0700 In-Reply-To: <20191028072032.6911-1-satyat@google.com> Message-Id: <20191028072032.6911-4-satyat@google.com> Mime-Version: 1.0 References: <20191028072032.6911-1-satyat@google.com> X-Mailer: git-send-email 2.24.0.rc0.303.g954a862665-goog Subject: [PATCH v5 3/9] block: blk-crypto for Inline Encryption From: Satya Tangirala To: linux-block@vger.kernel.org, linux-scsi@vger.kernel.org, linux-fscrypt@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net Cc: Barani Muthukumaran , Kuohong Wang , Kim Boojin , Satya Tangirala Sender: linux-fscrypt-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fscrypt@vger.kernel.org We introduce blk-crypto, which manages programming keyslots for struct bios. With blk-crypto, filesystems only need to call bio_crypt_set_ctx with the encryption key, algorithm and data_unit_num; they don't have to worry about getting a keyslot for each encryption context, as blk-crypto handles that. Blk-crypto also makes it possible for layered devices like device mapper to make use of inline encryption hardware. Blk-crypto delegates crypto operations to inline encryption hardware when available, and also contains a software fallback to the kernel crypto API. For more details, refer to Documentation/block/inline-encryption.rst. Signed-off-by: Satya Tangirala --- Documentation/block/index.rst | 1 + Documentation/block/inline-encryption.rst | 183 +++++ block/Kconfig | 2 + block/Makefile | 3 +- block/bio-crypt-ctx.c | 7 +- block/bio.c | 5 + block/blk-core.c | 11 +- block/blk-crypto.c | 798 ++++++++++++++++++++++ include/linux/bio-crypt-ctx.h | 7 + include/linux/blk-crypto.h | 62 ++ 10 files changed, 1076 insertions(+), 3 deletions(-) create mode 100644 Documentation/block/inline-encryption.rst create mode 100644 block/blk-crypto.c create mode 100644 include/linux/blk-crypto.h diff --git a/Documentation/block/index.rst b/Documentation/block/index.rst index 3fa7a52fafa4..026addfc69bc 100644 --- a/Documentation/block/index.rst +++ b/Documentation/block/index.rst @@ -14,6 +14,7 @@ Block cmdline-partition data-integrity deadline-iosched + inline-encryption ioprio kyber-iosched null_blk diff --git a/Documentation/block/inline-encryption.rst b/Documentation/block/inline-encryption.rst new file mode 100644 index 000000000000..202826cee95e --- /dev/null +++ b/Documentation/block/inline-encryption.rst @@ -0,0 +1,183 @@ +.. SPDX-License-Identifier: GPL-2.0 + +================= +Inline Encryption +================= + +Objective +========= + +We want to support inline encryption (IE) in the kernel. +To allow for testing, we also want a crypto API fallback when actual +IE hardware is absent. We also want IE to work with layered devices +like dm and loopback (i.e. we want to be able to use the IE hardware +of the underlying devices if present, or else fall back to crypto API +en/decryption). + + +Constraints and notes +===================== + +- IE hardware have a limited number of "keyslots" that can be programmed + with an encryption context (key, algorithm, data unit size, etc.) at any time. + One can specify a keyslot in a data request made to the device, and the + device will en/decrypt the data using the encryption context programmed into + that specified keyslot. When possible, we want to make multiple requests with + the same encryption context share the same keyslot. + +- We need a way for filesystems to specify an encryption context to use for + en/decrypting a struct bio, and a device driver (like UFS) needs to be able + to use that encryption context when it processes the bio. + +- We need a way for device drivers to expose their capabilities in a unified + way to the upper layers. + + +Design +====== + +We add a struct bio_crypt_ctx to struct bio that can represent an +encryption context, because we need to be able to pass this encryption +context from the FS layer to the device driver to act upon. + +While IE hardware works on the notion of keyslots, the FS layer has no +knowledge of keyslots - it simply wants to specify an encryption context to +use while en/decrypting a bio. + +We introduce a keyslot manager (KSM) that handles the translation from +encryption contexts specified by the FS to keyslots on the IE hardware. +This KSM also serves as the way IE hardware can expose their capabilities to +upper layers. The generic mode of operation is: each device driver that wants +to support IE will construct a KSM and set it up in its struct request_queue. +Upper layers that want to use IE on this device can then use this KSM in +the device's struct request_queue to translate an encryption context into +a keyslot. The presence of the KSM in the request queue shall be used to mean +that the device supports IE. + +On the device driver end of the interface, the device driver needs to tell the +KSM how to actually manipulate the IE hardware in the device to do things like +programming the crypto key into the IE hardware into a particular keyslot. All +this is achieved through the :c:type:`struct keyslot_mgmt_ll_ops` that the +device driver passes to the KSM when creating it. + +It uses refcounts to track which keyslots are idle (either they have no +encryption context programmed, or there are no in-flight struct bios +referencing that keyslot). When a new encryption context needs a keyslot, it +tries to find a keyslot that has already been programmed with the same +encryption context, and if there is no such keyslot, it evicts the least +recently used idle keyslot and programs the new encryption context into that +one. If no idle keyslots are available, then the caller will sleep until there +is at least one. + + +Blk-crypto +========== + +The above is sufficient for simple cases, but does not work if there is a +need for a crypto API fallback, or if we are want to use IE with layered +devices. To these ends, we introduce blk-crypto. Blk-crypto allows us to +present a unified view of encryption to the FS (so FS only needs to specify +an encryption context and not worry about keyslots at all), and blk-crypto +can decide whether to delegate the en/decryption to IE hardware or to the +crypto API. Blk-crypto maintains an internal KSM that serves as the crypto +API fallback. + +Blk-crypto needs to ensure that the encryption context is programmed into the +"correct" keyslot manager for IE. If a bio is submitted to a layered device +that eventually passes the bio down to a device that really does support IE, we +want the encryption context to be programmed into a keyslot for the KSM of the +device with IE support. However, blk-crypto does not know a priori whether a +particular device is the final device in the layering structure for a bio or +not. So in the case that a particular device does not support IE, since it is +possibly the final destination device for the bio, if the bio requires +encryption (i.e. the bio is doing a write operation), blk-crypto must fallback +to the crypto API *before* sending the bio to the device. + +Blk-crypto ensures that: + +- The bio's encryption context is programmed into a keyslot in the KSM of the + request queue that the bio is being submitted to (or the crypto API fallback + KSM if the request queue doesn't have a KSM), and that the ``processing_ksm`` + in the ``bi_crypt_context`` is set to this KSM + +- That the bio has its own individual reference to the keyslot in this KSM. + Once the bio passes through blk-crypto, its encryption context is programmed + in some KSM. The "its own individual reference to the keyslot" ensures that + keyslots can be released by each bio independently of other bios while + ensuring that the bio has a valid reference to the keyslot when, for e.g., the + crypto API fallback KSM in blk-crypto performs crypto on the device's behalf. + The individual references are ensured by increasing the refcount for the + keyslot in the ``processing_ksm`` when a bio with a programmed encryption + context is cloned. + + +What blk-crypto does on bio submission +-------------------------------------- + +**Case 1:** blk-crypto is given a bio with only an encryption context that hasn't +been programmed into any keyslot in any KSM (for e.g. a bio from the FS). + In this case, blk-crypto will program the encryption context into the KSM of the + request queue the bio is being submitted to (and if this KSM does not exist, + then it will program it into blk-crypto's internal KSM for crypto API + fallback). The KSM that this encryption context was programmed into is stored + as the ``processing_ksm`` in the bio's ``bi_crypt_context``. + +**Case 2:** blk-crypto is given a bio whose encryption context has already been +programmed into a keyslot in the *crypto API fallback* KSM. + In this case, blk-crypto does nothing; it treats the bio as not having + specified an encryption context. Note that we cannot do here what we will do + in Case 3 because we would have already encrypted the bio via the crypto API + by this point. + +**Case 3:** blk-crypto is given a bio whose encryption context has already been +programmed into a keyslot in some KSM (that is *not* the crypto API fallback +KSM). + In this case, blk-crypto first releases that keyslot from that KSM and then + treats the bio as in Case 1. + +This way, when a device driver is processing a bio, it can be sure that +the bio's encryption context has been programmed into some KSM (either the +device driver's request queue's KSM, or blk-crypto's crypto API fallback KSM). +It then simply needs to check if the bio's processing_ksm is the device's +request queue's KSM. If so, then it should proceed with IE. If not, it should +simply do nothing with respect to crypto, because some other KSM (perhaps the +blk-crypto crypto API fallback KSM) is handling the en/decryption. + +Blk-crypto will release the keyslot that is being held by the bio (and also +decrypt it if the bio is using the crypto API fallback KSM) once +``bio_remaining_done`` returns true for the bio. + + +Layered Devices +=============== + +Layered devices that wish to support IE need to create their own keyslot +manager for their request queue, and expose whatever functionality they choose. +When a layered device wants to pass a bio to another layer (either by +resubmitting the same bio, or by submitting a clone), it doesn't need to do +anything special because the bio (or the clone) will once again pass through +blk-crypto, which will work as described in Case 3. If a layered device wants +for some reason to do the IO by itself instead of passing it on to a child +device, but it also chose to expose IE capabilities by setting up a KSM in its +request queue, it is then responsible for en/decrypting the data itself. In +such cases, the device can choose to call the blk-crypto function +``blk_crypto_fallback_to_kernel_crypto_api`` (TODO: Not yet implemented), which will +cause the en/decryption to be done via the crypto API fallback. + + +Future Optimizations for layered devices +======================================== + +Creating a keyslot manager for the layered device uses up memory for each +keyslot, and in general, a layered device (like dm-linear) merely passes the +request on to a "child" device, so the keyslots in the layered device itself +might be completely unused. We can instead define a new type of KSM; the +"passthrough KSM", that layered devices can use to let blk-crypto know that +this layered device *will* pass the bio to some child device (and hence +through blk-crypto again, at which point blk-crypto can program the encryption +context, instead of programming it into the layered device's KSM). Again, if +the device "lies" and decides to do the IO itself instead of passing it on to +a child device, it is responsible for doing the en/decryption (and can choose +to call ``blk_crypto_fallback_to_kernel_crypto_api``). Another use case for the +"passthrough KSM" is for IE devices that want to manage their own keyslots/do +not have a limited number of keyslots. diff --git a/block/Kconfig b/block/Kconfig index ae52d42b783b..606a67e47e68 100644 --- a/block/Kconfig +++ b/block/Kconfig @@ -179,6 +179,8 @@ config BLK_SED_OPAL config BLK_INLINE_ENCRYPTION bool "Enable inline encryption support in block layer" + select CRYPTO + select CRYPTO_BLKCIPHER help Build the blk-crypto subsystem. Enabling this lets the block layer handle encryption, diff --git a/block/Makefile b/block/Makefile index f39611ed151f..8932c7e4fd07 100644 --- a/block/Makefile +++ b/block/Makefile @@ -36,4 +36,5 @@ obj-$(CONFIG_BLK_DEBUG_FS) += blk-mq-debugfs.o obj-$(CONFIG_BLK_DEBUG_FS_ZONED)+= blk-mq-debugfs-zoned.o obj-$(CONFIG_BLK_SED_OPAL) += sed-opal.o obj-$(CONFIG_BLK_PM) += blk-pm.o -obj-$(CONFIG_BLK_INLINE_ENCRYPTION) += keyslot-manager.o bio-crypt-ctx.o +obj-$(CONFIG_BLK_INLINE_ENCRYPTION) += keyslot-manager.o bio-crypt-ctx.o \ + blk-crypto.o diff --git a/block/bio-crypt-ctx.c b/block/bio-crypt-ctx.c index aa3571f72ee7..6a2b061865c6 100644 --- a/block/bio-crypt-ctx.c +++ b/block/bio-crypt-ctx.c @@ -43,7 +43,12 @@ EXPORT_SYMBOL(bio_crypt_free_ctx); int bio_crypt_clone(struct bio *dst, struct bio *src, gfp_t gfp_mask) { - if (!bio_has_crypt_ctx(src)) + /* + * If a bio is swhandled, then it will be decrypted when bio_endio + * is called. As we only want the data to be decrypted once, copies + * of the bio must not have have a crypt context. + */ + if (!bio_has_crypt_ctx(src) || bio_crypt_swhandled(src)) return 0; dst->bi_crypt_context = bio_crypt_alloc_ctx(gfp_mask); diff --git a/block/bio.c b/block/bio.c index ce8003aadf07..36a1712328d0 100644 --- a/block/bio.c +++ b/block/bio.c @@ -17,6 +17,7 @@ #include #include #include +#include #include #include "blk.h" @@ -1788,6 +1789,10 @@ void bio_endio(struct bio *bio) again: if (!bio_remaining_done(bio)) return; + + if (!blk_crypto_endio(bio)) + return; + if (!bio_integrity_endio(bio)) return; diff --git a/block/blk-core.c b/block/blk-core.c index 3b5959d386fb..0f7e81dbe2ee 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -38,6 +38,7 @@ #include #include #include +#include #define CREATE_TRACE_POINTS #include @@ -1061,7 +1062,9 @@ blk_qc_t generic_make_request(struct bio *bio) /* Create a fresh bio_list for all subordinate requests */ bio_list_on_stack[1] = bio_list_on_stack[0]; bio_list_init(&bio_list_on_stack[0]); - ret = q->make_request_fn(q, bio); + + if (!blk_crypto_submit_bio(&bio)) + ret = q->make_request_fn(q, bio); blk_queue_exit(q); @@ -1114,6 +1117,9 @@ blk_qc_t direct_make_request(struct bio *bio) if (!generic_make_request_checks(bio)) return BLK_QC_T_NONE; + if (blk_crypto_submit_bio(&bio)) + return BLK_QC_T_NONE; + if (unlikely(blk_queue_enter(q, nowait ? BLK_MQ_REQ_NOWAIT : 0))) { if (nowait && !blk_queue_dying(q)) bio->bi_status = BLK_STS_AGAIN; @@ -1810,5 +1816,8 @@ int __init blk_dev_init(void) if (bio_crypt_ctx_init() < 0) panic("Failed to allocate mem for bio crypt ctxs\n"); + if (blk_crypto_init() < 0) + panic("Failed to init blk-crypto\n"); + return 0; } diff --git a/block/blk-crypto.c b/block/blk-crypto.c new file mode 100644 index 000000000000..89649655bf4b --- /dev/null +++ b/block/blk-crypto.c @@ -0,0 +1,798 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright 2019 Google LLC + */ + +/* + * Refer to Documentation/block/inline-encryption.rst for detailed explanation. + */ + +#define pr_fmt(fmt) "blk-crypto: " fmt + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/* Represents a crypto mode supported by blk-crypto */ +struct blk_crypto_mode { + const char *cipher_str; /* crypto API name (for fallback case) */ + size_t keysize; /* key size in bytes */ +}; + +static const struct blk_crypto_mode blk_crypto_modes[] = { + [BLK_ENCRYPTION_MODE_AES_256_XTS] = { + .cipher_str = "xts(aes)", + .keysize = 64, + }, +}; + +static unsigned int num_prealloc_bounce_pg = 32; +module_param(num_prealloc_bounce_pg, uint, 0); +MODULE_PARM_DESC(num_prealloc_bounce_pg, + "Number of preallocated bounce pages for blk-crypto to use during crypto API fallback encryption"); + +#define BLK_CRYPTO_MAX_KEY_SIZE 64 +static int blk_crypto_num_keyslots = 100; +module_param_named(num_keyslots, blk_crypto_num_keyslots, int, 0); +MODULE_PARM_DESC(num_keyslots, + "Number of keyslots for crypto API fallback in blk-crypto."); + +static struct blk_crypto_keyslot { + struct crypto_skcipher *tfm; + enum blk_crypto_mode_num crypto_mode; + u8 key[BLK_CRYPTO_MAX_KEY_SIZE]; + struct crypto_skcipher *tfms[ARRAY_SIZE(blk_crypto_modes)]; +} *blk_crypto_keyslots; + +/* + * Allocating a crypto tfm during I/O can deadlock, so we have to preallocate + * all of a mode's tfms when that mode starts being used. Since each mode may + * need all the keyslots at some point, each mode needs its own tfm for each + * keyslot; thus, a keyslot may contain tfms for multiple modes. However, to + * match the behavior of real inline encryption hardware (which only supports a + * single encryption context per keyslot), we only allow one tfm per keyslot to + * be used at a time - the rest of the unused tfms have their keys cleared. + */ +static struct mutex tfms_lock[ARRAY_SIZE(blk_crypto_modes)]; +static bool tfms_inited[ARRAY_SIZE(blk_crypto_modes)]; + +struct work_mem { + struct work_struct crypto_work; + struct bio *bio; +}; + +/* The following few vars are only used during the crypto API fallback */ +static struct keyslot_manager *blk_crypto_ksm; +static struct workqueue_struct *blk_crypto_wq; +static mempool_t *blk_crypto_page_pool; +static struct kmem_cache *blk_crypto_work_mem_cache; + +bool bio_crypt_swhandled(struct bio *bio) +{ + return bio_has_crypt_ctx(bio) && + bio->bi_crypt_context->processing_ksm == blk_crypto_ksm; +} + +static u8 blank_key[BLK_CRYPTO_MAX_KEY_SIZE]; +static void evict_keyslot(unsigned int slot) +{ + struct blk_crypto_keyslot *slotp = &blk_crypto_keyslots[slot]; + enum blk_crypto_mode_num crypto_mode = slotp->crypto_mode; + int err; + + WARN_ON(slotp->crypto_mode == BLK_ENCRYPTION_MODE_INVALID); + + /* Clear the key in the skcipher */ + err = crypto_skcipher_setkey(slotp->tfms[crypto_mode], blank_key, + blk_crypto_modes[crypto_mode].keysize); + WARN_ON(err); + memzero_explicit(slotp->key, BLK_CRYPTO_MAX_KEY_SIZE); + slotp->crypto_mode = BLK_ENCRYPTION_MODE_INVALID; +} + +static int blk_crypto_keyslot_program(void *priv, const u8 *key, + enum blk_crypto_mode_num crypto_mode, + unsigned int data_unit_size, + unsigned int slot) +{ + struct blk_crypto_keyslot *slotp = &blk_crypto_keyslots[slot]; + const struct blk_crypto_mode *mode = &blk_crypto_modes[crypto_mode]; + size_t keysize = mode->keysize; + int err; + + if (crypto_mode != slotp->crypto_mode && + slotp->crypto_mode != BLK_ENCRYPTION_MODE_INVALID) { + evict_keyslot(slot); + } + + if (!slotp->tfms[crypto_mode]) + return -ENOMEM; + slotp->crypto_mode = crypto_mode; + err = crypto_skcipher_setkey(slotp->tfms[crypto_mode], key, keysize); + + if (err) { + evict_keyslot(slot); + return err; + } + + memcpy(slotp->key, key, keysize); + + return 0; +} + +static int blk_crypto_keyslot_evict(void *priv, const u8 *key, + enum blk_crypto_mode_num crypto_mode, + unsigned int data_unit_size, + unsigned int slot) +{ + evict_keyslot(slot); + return 0; +} + +static int blk_crypto_keyslot_find(void *priv, + const u8 *key, + enum blk_crypto_mode_num crypto_mode, + unsigned int data_unit_size_bytes) +{ + int slot; + const size_t keysize = blk_crypto_modes[crypto_mode].keysize; + + for (slot = 0; slot < blk_crypto_num_keyslots; slot++) { + if (blk_crypto_keyslots[slot].crypto_mode == crypto_mode && + !crypto_memneq(blk_crypto_keyslots[slot].key, key, keysize)) + return slot; + } + + return -ENOKEY; +} + +static bool blk_crypto_mode_supported(void *priv, + enum blk_crypto_mode_num crypt_mode, + unsigned int data_unit_size) +{ + /* All blk_crypto_modes are required to have a crypto API fallback. */ + return true; +} + +/* + * The crypto API fallback KSM ops - only used for a bio when it specifies a + * blk_crypto_mode for which we failed to get a keyslot in the device's inline + * encryption hardware (which probably means the device doesn't have inline + * encryption hardware that supports that crypto mode). + */ +static const struct keyslot_mgmt_ll_ops blk_crypto_ksm_ll_ops = { + .keyslot_program = blk_crypto_keyslot_program, + .keyslot_evict = blk_crypto_keyslot_evict, + .keyslot_find = blk_crypto_keyslot_find, + .crypto_mode_supported = blk_crypto_mode_supported, +}; + +static void blk_crypto_encrypt_endio(struct bio *enc_bio) +{ + struct bio *src_bio = enc_bio->bi_private; + int i; + + for (i = 0; i < enc_bio->bi_vcnt; i++) + mempool_free(enc_bio->bi_io_vec[i].bv_page, + blk_crypto_page_pool); + + src_bio->bi_status = enc_bio->bi_status; + + bio_put(enc_bio); + bio_endio(src_bio); +} + +static struct bio *blk_crypto_clone_bio(struct bio *bio_src) +{ + struct bvec_iter iter; + struct bio_vec bv; + struct bio *bio; + + bio = bio_alloc_bioset(GFP_NOIO, bio_segments(bio_src), NULL); + if (!bio) + return NULL; + bio->bi_disk = bio_src->bi_disk; + bio->bi_opf = bio_src->bi_opf; + bio->bi_ioprio = bio_src->bi_ioprio; + bio->bi_write_hint = bio_src->bi_write_hint; + bio->bi_iter.bi_sector = bio_src->bi_iter.bi_sector; + bio->bi_iter.bi_size = bio_src->bi_iter.bi_size; + + bio_for_each_segment(bv, bio_src, iter) + bio->bi_io_vec[bio->bi_vcnt++] = bv; + + if (bio_integrity(bio_src) && + bio_integrity_clone(bio, bio_src, GFP_NOIO) < 0) { + bio_put(bio); + return NULL; + } + + bio_clone_blkg_association(bio, bio_src); + blkcg_bio_issue_init(bio); + + return bio; +} + +/* Check that all I/O segments are data unit aligned */ +static int bio_crypt_check_alignment(struct bio *bio) +{ + int data_unit_size = 1 << bio->bi_crypt_context->data_unit_size_bits; + struct bvec_iter iter; + struct bio_vec bv; + + bio_for_each_segment(bv, bio, iter) { + if (!IS_ALIGNED(bv.bv_len | bv.bv_offset, data_unit_size)) + return -EIO; + } + return 0; +} + +static int blk_crypto_alloc_cipher_req(struct bio *src_bio, + struct skcipher_request **ciph_req_ptr, + struct crypto_wait *wait) +{ + int slot; + struct skcipher_request *ciph_req; + struct blk_crypto_keyslot *slotp; + + slot = bio_crypt_get_keyslot(src_bio); + slotp = &blk_crypto_keyslots[slot]; + ciph_req = skcipher_request_alloc(slotp->tfms[slotp->crypto_mode], + GFP_NOIO); + if (!ciph_req) { + src_bio->bi_status = BLK_STS_RESOURCE; + return -ENOMEM; + } + + skcipher_request_set_callback(ciph_req, + CRYPTO_TFM_REQ_MAY_BACKLOG | + CRYPTO_TFM_REQ_MAY_SLEEP, + crypto_req_done, wait); + *ciph_req_ptr = ciph_req; + return 0; +} + +static int blk_crypto_split_bio_if_needed(struct bio **bio_ptr) +{ + struct bio *bio = *bio_ptr; + unsigned int i = 0; + unsigned int num_sectors = 0; + struct bio_vec bv; + struct bvec_iter iter; + + bio_for_each_segment(bv, bio, iter) { + num_sectors += bv.bv_len >> SECTOR_SHIFT; + if (++i == BIO_MAX_PAGES) + break; + } + if (num_sectors < bio_sectors(bio)) { + struct bio *split_bio; + + split_bio = bio_split(bio, num_sectors, GFP_NOIO, NULL); + if (!split_bio) { + bio->bi_status = BLK_STS_RESOURCE; + return -ENOMEM; + } + bio_chain(split_bio, bio); + generic_make_request(bio); + *bio_ptr = split_bio; + } + return 0; +} + +/* + * The crypto API fallback's encryption routine. + * Allocate a bounce bio for encryption, encrypt the input bio using + * crypto API, and replace *bio_ptr with the bounce bio. May split input + * bio if it's too large. + */ +static int blk_crypto_encrypt_bio(struct bio **bio_ptr) +{ + struct bio *src_bio; + struct skcipher_request *ciph_req = NULL; + DECLARE_CRYPTO_WAIT(wait); + int err = 0; + u64 curr_dun; + union { + __le64 dun; + u8 bytes[16]; + } iv; + struct scatterlist src, dst; + struct bio *enc_bio; + struct bio_vec *enc_bvec; + int i, j; + int data_unit_size; + + /* Split the bio if it's too big for single page bvec */ + err = blk_crypto_split_bio_if_needed(bio_ptr); + if (err) + return err; + + src_bio = *bio_ptr; + data_unit_size = 1 << src_bio->bi_crypt_context->data_unit_size_bits; + + /* Allocate bounce bio for encryption */ + enc_bio = blk_crypto_clone_bio(src_bio); + if (!enc_bio) { + src_bio->bi_status = BLK_STS_RESOURCE; + return -ENOMEM; + } + + /* + * Use the crypto API fallback keyslot manager to get a crypto_skcipher + * for the algorithm and key specified for this bio. + */ + err = bio_crypt_ctx_acquire_keyslot(src_bio, blk_crypto_ksm); + if (err) { + src_bio->bi_status = BLK_STS_IOERR; + goto out_put_enc_bio; + } + + /* and then allocate an skcipher_request for it */ + err = blk_crypto_alloc_cipher_req(src_bio, &ciph_req, &wait); + if (err) + goto out_release_keyslot; + + curr_dun = bio_crypt_data_unit_num(src_bio); + sg_init_table(&src, 1); + sg_init_table(&dst, 1); + + skcipher_request_set_crypt(ciph_req, &src, &dst, + data_unit_size, iv.bytes); + + /* Encrypt each page in the bounce bio */ + for (i = 0, enc_bvec = enc_bio->bi_io_vec; i < enc_bio->bi_vcnt; + enc_bvec++, i++) { + struct page *plaintext_page = enc_bvec->bv_page; + struct page *ciphertext_page = + mempool_alloc(blk_crypto_page_pool, GFP_NOIO); + + enc_bvec->bv_page = ciphertext_page; + + if (!ciphertext_page) { + src_bio->bi_status = BLK_STS_RESOURCE; + err = -ENOMEM; + goto out_free_bounce_pages; + } + + sg_set_page(&src, plaintext_page, data_unit_size, + enc_bvec->bv_offset); + sg_set_page(&dst, ciphertext_page, data_unit_size, + enc_bvec->bv_offset); + + /* Encrypt each data unit in this page */ + for (j = 0; j < enc_bvec->bv_len; j += data_unit_size) { + memset(&iv, 0, sizeof(iv)); + iv.dun = cpu_to_le64(curr_dun); + + err = crypto_wait_req(crypto_skcipher_encrypt(ciph_req), + &wait); + if (err) { + i++; + src_bio->bi_status = BLK_STS_RESOURCE; + goto out_free_bounce_pages; + } + curr_dun++; + src.offset += data_unit_size; + dst.offset += data_unit_size; + } + } + + enc_bio->bi_private = src_bio; + enc_bio->bi_end_io = blk_crypto_encrypt_endio; + *bio_ptr = enc_bio; + + enc_bio = NULL; + err = 0; + goto out_free_ciph_req; + +out_free_bounce_pages: + while (i > 0) + mempool_free(enc_bio->bi_io_vec[--i].bv_page, + blk_crypto_page_pool); +out_free_ciph_req: + skcipher_request_free(ciph_req); +out_release_keyslot: + bio_crypt_ctx_release_keyslot(src_bio); +out_put_enc_bio: + if (enc_bio) + bio_put(enc_bio); + + return err; +} + +/* + * The crypto API fallback's main decryption routine. + * Decrypts input bio in place. + */ +static void blk_crypto_decrypt_bio(struct work_struct *w) +{ + struct work_mem *work_mem = + container_of(w, struct work_mem, crypto_work); + struct bio *bio = work_mem->bio; + struct skcipher_request *ciph_req = NULL; + DECLARE_CRYPTO_WAIT(wait); + struct bio_vec bv; + struct bvec_iter iter; + u64 curr_dun; + union { + __le64 dun; + u8 bytes[16]; + } iv; + struct scatterlist sg; + int data_unit_size = 1 << bio->bi_crypt_context->data_unit_size_bits; + int i; + int err; + + /* + * Use the crypto API fallback keyslot manager to get a crypto_skcipher + * for the algorithm and key specified for this bio. + */ + if (bio_crypt_ctx_acquire_keyslot(bio, blk_crypto_ksm)) { + bio->bi_status = BLK_STS_RESOURCE; + goto out_no_keyslot; + } + + /* and then allocate an skcipher_request for it */ + err = blk_crypto_alloc_cipher_req(bio, &ciph_req, &wait); + if (err) + goto out; + + curr_dun = bio_crypt_sw_data_unit_num(bio); + sg_init_table(&sg, 1); + skcipher_request_set_crypt(ciph_req, &sg, &sg, data_unit_size, + iv.bytes); + + /* Decrypt each segment in the bio */ + __bio_for_each_segment(bv, bio, iter, + bio->bi_crypt_context->crypt_iter) { + struct page *page = bv.bv_page; + + sg_set_page(&sg, page, data_unit_size, bv.bv_offset); + + /* Decrypt each data unit in the segment */ + for (i = 0; i < bv.bv_len; i += data_unit_size) { + memset(&iv, 0, sizeof(iv)); + iv.dun = cpu_to_le64(curr_dun); + if (crypto_wait_req(crypto_skcipher_decrypt(ciph_req), + &wait)) { + bio->bi_status = BLK_STS_IOERR; + goto out; + } + curr_dun++; + sg.offset += data_unit_size; + } + } + +out: + skcipher_request_free(ciph_req); + bio_crypt_ctx_release_keyslot(bio); +out_no_keyslot: + kmem_cache_free(blk_crypto_work_mem_cache, work_mem); + bio_endio(bio); +} + +/* Queue bio for decryption */ +static void blk_crypto_queue_decrypt_bio(struct bio *bio) +{ + struct work_mem *work_mem = + kmem_cache_zalloc(blk_crypto_work_mem_cache, GFP_ATOMIC); + + if (!work_mem) { + bio->bi_status = BLK_STS_RESOURCE; + bio_endio(bio); + return; + } + + INIT_WORK(&work_mem->crypto_work, blk_crypto_decrypt_bio); + work_mem->bio = bio; + queue_work(blk_crypto_wq, &work_mem->crypto_work); +} + +/** + * blk_crypto_submit_bio - handle submitting bio for inline encryption + * + * @bio_ptr: pointer to original bio pointer + * + * If the bio doesn't have inline encryption enabled or the submitter already + * specified a keyslot for the target device, do nothing. Else, a raw key must + * have been provided, so acquire a device keyslot for it if supported. Else, + * use the crypto API fallback. + * + * When the crypto API fallback is used for encryption, blk-crypto may choose to + * split the bio into 2 - the first one that will continue to be processed and + * the second one that will be resubmitted via generic_make_request. + * A bounce bio will be allocated to encrypt the contents of the aforementioned + * "first one", and *bio_ptr will be updated to this bounce bio. + * + * Return: 0 if bio submission should continue; nonzero if bio_endio() was + * already called so bio submission should abort. + */ +int blk_crypto_submit_bio(struct bio **bio_ptr) +{ + struct bio *bio = *bio_ptr; + struct request_queue *q; + int err; + struct bio_crypt_ctx *crypt_ctx; + + if (!bio_has_crypt_ctx(bio) || !bio_has_data(bio)) + return 0; + + /* + * When a read bio is marked for sw decryption, its bi_iter is saved + * so that when we decrypt the bio later, we know what part of it was + * marked for sw decryption (when the bio is passed down after + * blk_crypto_submit bio, it may be split or advanced so we cannot rely + * on the bi_iter while decrypting in blk_crypto_endio) + */ + if (bio_crypt_swhandled(bio)) + return 0; + + err = bio_crypt_check_alignment(bio); + if (err) { + bio->bi_status = BLK_STS_IOERR; + goto out; + } + + crypt_ctx = bio->bi_crypt_context; + q = bio->bi_disk->queue; + + if (bio_crypt_has_keyslot(bio)) { + /* Key already programmed into device? */ + if (q->ksm == crypt_ctx->processing_ksm) + return 0; + + /* Nope, release the existing keyslot. */ + bio_crypt_ctx_release_keyslot(bio); + } + + /* Get device keyslot if supported */ + if (q->ksm) { + err = bio_crypt_ctx_acquire_keyslot(bio, q->ksm); + if (!err) + return 0; + + pr_warn_once("Failed to acquire keyslot for %s (err=%d). Falling back to crypto API.\n", + bio->bi_disk->disk_name, err); + } + + /* Fallback to crypto API */ + if (!READ_ONCE(tfms_inited[bio->bi_crypt_context->crypto_mode])) { + err = -EIO; + bio->bi_status = BLK_STS_IOERR; + goto out; + } + + if (bio_data_dir(bio) == WRITE) { + /* Encrypt the data now */ + err = blk_crypto_encrypt_bio(bio_ptr); + if (err) + goto out; + } else { + /* Mark bio as swhandled */ + bio->bi_crypt_context->processing_ksm = blk_crypto_ksm; + bio->bi_crypt_context->crypt_iter = bio->bi_iter; + bio->bi_crypt_context->sw_data_unit_num = + bio->bi_crypt_context->data_unit_num; + } + return 0; +out: + bio_endio(*bio_ptr); + return err; +} + +/** + * blk_crypto_endio - clean up bio w.r.t inline encryption during bio_endio + * + * @bio - the bio to clean up + * + * If blk_crypto_submit_bio decided to fallback to crypto API for this + * bio, we queue the bio for decryption into a workqueue and return false, + * and call bio_endio(bio) at a later time (after the bio has been decrypted). + * + * If the bio is not to be decrypted by the crypto API, this function releases + * the reference to the keyslot that blk_crypto_submit_bio got. + * + * Return: true if bio_endio should continue; false otherwise (bio_endio will + * be called again when bio has been decrypted). + */ +bool blk_crypto_endio(struct bio *bio) +{ + if (!bio_has_crypt_ctx(bio)) + return true; + + if (bio_crypt_swhandled(bio)) { + /* + * The only bios that are swhandled when they reach here + * are those with bio_data_dir(bio) == READ, since WRITE + * bios that are encrypted by the crypto API fallback are + * handled by blk_crypto_encrypt_endio. + */ + + /* If there was an IO error, don't decrypt. */ + if (bio->bi_status) + return true; + + blk_crypto_queue_decrypt_bio(bio); + return false; + } + + if (bio_crypt_has_keyslot(bio)) + bio_crypt_ctx_release_keyslot(bio); + + return true; +} + +/** + * blk_crypto_start_using_mode() - Allocate skciphers for a + * mode_num for all keyslots + * @mode_num - the blk_crypto_mode we want to allocate ciphers for. + * + * Upper layers (filesystems) should call this function to ensure that a + * the crypto API fallback has transforms for this algorithm, if they become + * necessary. + * + * Return: 0 on success and -err on error. + */ +int blk_crypto_start_using_mode(enum blk_crypto_mode_num mode_num, + unsigned int data_unit_size, + struct request_queue *q) +{ + struct blk_crypto_keyslot *slotp; + int err = 0; + int i; + + /* + * Fast path + * Ensure that updates to blk_crypto_keyslots[i].tfms[mode_num] + * for each i are visible before we try to access them. + */ + if (likely(smp_load_acquire(&tfms_inited[mode_num]))) + return 0; + + /* + * If the keyslot manager of the request queue supports this + * crypto mode, then we don't need to allocate this mode. + */ + if (keyslot_manager_crypto_mode_supported(q->ksm, mode_num, + data_unit_size)) { + return 0; + } + + mutex_lock(&tfms_lock[mode_num]); + if (likely(tfms_inited[mode_num])) + goto out; + + for (i = 0; i < blk_crypto_num_keyslots; i++) { + slotp = &blk_crypto_keyslots[i]; + slotp->tfms[mode_num] = crypto_alloc_skcipher( + blk_crypto_modes[mode_num].cipher_str, + 0, 0); + if (IS_ERR(slotp->tfms[mode_num])) { + err = PTR_ERR(slotp->tfms[mode_num]); + slotp->tfms[mode_num] = NULL; + goto out_free_tfms; + } + + crypto_skcipher_set_flags(slotp->tfms[mode_num], + CRYPTO_TFM_REQ_FORBID_WEAK_KEYS); + } + + /* + * Ensure that updates to blk_crypto_keyslots[i].tfms[mode_num] + * for each i are visible before we set tfms_inited[mode_num]. + */ + smp_store_release(&tfms_inited[mode_num], true); + goto out; + +out_free_tfms: + for (i = 0; i < blk_crypto_num_keyslots; i++) { + slotp = &blk_crypto_keyslots[i]; + crypto_free_skcipher(slotp->tfms[mode_num]); + slotp->tfms[mode_num] = NULL; + } +out: + mutex_unlock(&tfms_lock[mode_num]); + return err; +} +EXPORT_SYMBOL(blk_crypto_start_using_mode); + +/** + * blk_crypto_evict_key() - Evict a key from any inline encryption hardware + * it may have been programmed into + * @q - The request queue who's keyslot manager this key might have been + * programmed into + * @key - The key to evict + * @mode - The blk_crypto_mode_num used with this key + * @data_unit_size - The data unit size used with this key + * + * Upper layers (filesystems) should call this function to ensure that a key + * is evicted from hardware that it might have been programmed into. This + * will call keyslot_manager_evict_key on the queue's keyslot manager, if one + * exists, and supports the crypto algorithm with the specified data unit size. + * Otherwise, it will evict the key from the blk_crypto_ksm. + * + * Return: 0 on success, -err on error. + */ +int blk_crypto_evict_key(struct request_queue *q, const u8 *key, + enum blk_crypto_mode_num mode, + unsigned int data_unit_size) +{ + struct keyslot_manager *ksm = blk_crypto_ksm; + + if (q && q->ksm && keyslot_manager_crypto_mode_supported(q->ksm, mode, + data_unit_size)) { + ksm = q->ksm; + } + + return keyslot_manager_evict_key(ksm, key, mode, data_unit_size); +} +EXPORT_SYMBOL(blk_crypto_evict_key); + +int __init blk_crypto_init(void) +{ + int i; + int err = -ENOMEM; + + prandom_bytes(blank_key, BLK_CRYPTO_MAX_KEY_SIZE); + + blk_crypto_ksm = keyslot_manager_create(blk_crypto_num_keyslots, + &blk_crypto_ksm_ll_ops, + NULL); + if (!blk_crypto_ksm) + goto out; + + blk_crypto_wq = alloc_workqueue("blk_crypto_wq", + WQ_UNBOUND | WQ_HIGHPRI | + WQ_MEM_RECLAIM, + num_online_cpus()); + if (!blk_crypto_wq) + goto out_free_ksm; + + blk_crypto_keyslots = kcalloc(blk_crypto_num_keyslots, + sizeof(*blk_crypto_keyslots), + GFP_KERNEL); + if (!blk_crypto_keyslots) + goto out_free_workqueue; + + for (i = 0; i < blk_crypto_num_keyslots; i++) { + blk_crypto_keyslots[i].crypto_mode = + BLK_ENCRYPTION_MODE_INVALID; + } + + for (i = 0; i < ARRAY_SIZE(blk_crypto_modes); i++) + mutex_init(&tfms_lock[i]); + + blk_crypto_page_pool = + mempool_create_page_pool(num_prealloc_bounce_pg, 0); + if (!blk_crypto_page_pool) + goto out_free_keyslots; + + blk_crypto_work_mem_cache = KMEM_CACHE(work_mem, SLAB_RECLAIM_ACCOUNT); + if (!blk_crypto_work_mem_cache) + goto out_free_page_pool; + + return 0; + +out_free_page_pool: + mempool_destroy(blk_crypto_page_pool); + blk_crypto_page_pool = NULL; +out_free_keyslots: + kzfree(blk_crypto_keyslots); + blk_crypto_keyslots = NULL; +out_free_workqueue: + destroy_workqueue(blk_crypto_wq); + blk_crypto_wq = NULL; +out_free_ksm: + keyslot_manager_destroy(blk_crypto_ksm); + blk_crypto_ksm = NULL; +out: + pr_warn("No memory for blk-crypto crypto API fallback."); + return err; +} diff --git a/include/linux/bio-crypt-ctx.h b/include/linux/bio-crypt-ctx.h index 5cd569f77c31..7c389f310bab 100644 --- a/include/linux/bio-crypt-ctx.h +++ b/include/linux/bio-crypt-ctx.h @@ -53,6 +53,8 @@ static inline void bio_crypt_advance(struct bio *bio, unsigned int bytes) } } +extern bool bio_crypt_swhandled(struct bio *bio); + static inline bool bio_crypt_has_keyslot(struct bio *bio) { return bio->bi_crypt_context->keyslot >= 0; @@ -170,6 +172,11 @@ static inline void bio_crypt_set_ctx(struct bio *bio, unsigned int dun_bits, gfp_t gfp_mask) { } +static inline bool bio_crypt_swhandled(struct bio *bio) +{ + return false; +} + static inline void bio_set_data_unit_num(struct bio *bio, u64 dun) { } static inline bool bio_crypt_has_keyslot(struct bio *bio) diff --git a/include/linux/blk-crypto.h b/include/linux/blk-crypto.h new file mode 100644 index 000000000000..2a07401244a6 --- /dev/null +++ b/include/linux/blk-crypto.h @@ -0,0 +1,62 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright 2019 Google LLC + */ + +#ifndef __LINUX_BLK_CRYPTO_H +#define __LINUX_BLK_CRYPTO_H + +#include +#include + +#ifdef CONFIG_BLK_INLINE_ENCRYPTION + +int blk_crypto_init(void); + +int blk_crypto_submit_bio(struct bio **bio_ptr); + +bool blk_crypto_endio(struct bio *bio); + +int blk_crypto_start_using_mode(enum blk_crypto_mode_num mode_num, + unsigned int data_unit_size, + struct request_queue *q); + +int blk_crypto_evict_key(struct request_queue *q, const u8 *key, + enum blk_crypto_mode_num mode, + unsigned int data_unit_size); + +#else /* CONFIG_BLK_INLINE_ENCRYPTION */ + +static inline int blk_crypto_init(void) +{ + return 0; +} + +static inline int blk_crypto_submit_bio(struct bio **bio_ptr) +{ + return 0; +} + +static inline bool blk_crypto_endio(struct bio *bio) +{ + return true; +} + +static inline int +blk_crypto_start_using_mode(enum blk_crypto_mode_num mode_num, + unsigned int data_unit_size, + struct request_queue *q) +{ + return -EOPNOTSUPP; +} + +static inline int blk_crypto_evict_key(struct request_queue *q, const u8 *key, + enum blk_crypto_mode_num mode, + unsigned int data_unit_size) +{ + return 0; +} + +#endif /* CONFIG_BLK_INLINE_ENCRYPTION */ + +#endif /* __LINUX_BLK_CRYPTO_H */