From patchwork Thu May 4 04:03:27 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 13230758 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id ED359C7EE23 for ; Thu, 4 May 2023 04:03:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229494AbjEDEDj (ORCPT ); Thu, 4 May 2023 00:03:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59814 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229462AbjEDEDi (ORCPT ); Thu, 4 May 2023 00:03:38 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D4D0F19B3; Wed, 3 May 2023 21:03:36 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 68FEA6316A; Thu, 4 May 2023 04:03:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9A1ECC4339B; Thu, 4 May 2023 04:03:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1683173015; bh=qXDuxQYZvqfrT22PqduCTlKO2Ix9HYdK/B5FDP1BLrs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YP3uSrzIBXYdO/jSqOjcRVrFM69Rs9x3MvCklVhSpUEuCUt62aM9JsTXknDg31Cct 57AoKFhWozUg7WysnWiXZKSv6UCwEDaNCThmGpaLiEJw6AM7DXyZg9Fkdz9y0LEOIa wfIyPcB4WI5AJ9iCayhwpUGU6m8yyCn3VLSp7mQ56gIn/65qy2p88SsQkNsjqBZeL+ O2NqVVubrx/dp9/ezSClOV/EBP3rpjuTCkF8UFW6BvGmEm8zZC7A7WfnV1vrj6srJy 5d6L2PwcjnR+VzkgMGXee57tHQ9zaOYD9zKtQ8KrXDGwM0Aan3cxyLivFlkOBq0fWP tlCyd8x1kBcNg== From: Eric Biggers To: stable@vger.kernel.org Cc: linux-block@vger.kernel.org, Nathan Huckleberry , Christoph Hellwig , Jens Axboe Subject: [PATCH 5.15 1/3] blk-mq: release crypto keyslot before reporting I/O complete Date: Wed, 3 May 2023 21:03:27 -0700 Message-Id: <20230504040329.106127-2-ebiggers@kernel.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230504040329.106127-1-ebiggers@kernel.org> References: <20230504040329.106127-1-ebiggers@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org From: Eric Biggers commit 9cd1e566676bbcb8a126acd921e4e194e6339603 upstream. Once all I/O using a blk_crypto_key has completed, filesystems can call blk_crypto_evict_key(). However, the block layer currently doesn't call blk_crypto_put_keyslot() until the request is being freed, which happens after upper layers have been told (via bio_endio()) the I/O has completed. This causes a race condition where blk_crypto_evict_key() can see 'slot_refs != 0' without there being an actual bug. This makes __blk_crypto_evict_key() hit the 'WARN_ON_ONCE(atomic_read(&slot->slot_refs) != 0)' and return without doing anything, eventually causing a use-after-free in blk_crypto_reprogram_all_keys(). (This is a very rare bug and has only been seen when per-file keys are being used with fscrypt.) There are two options to fix this: either release the keyslot before bio_endio() is called on the request's last bio, or make __blk_crypto_evict_key() ignore slot_refs. Let's go with the first solution, since it preserves the ability to report bugs (via WARN_ON_ONCE) where a key is evicted while still in-use. Fixes: a892c8d52c02 ("block: Inline encryption support for blk-mq") Cc: stable@vger.kernel.org Reviewed-by: Nathan Huckleberry Reviewed-by: Christoph Hellwig Signed-off-by: Eric Biggers Link: https://lore.kernel.org/r/20230315183907.53675-2-ebiggers@kernel.org Signed-off-by: Jens Axboe --- block/blk-core.c | 7 +++++++ block/blk-crypto-internal.h | 25 +++++++++++++++++++++---- block/blk-crypto.c | 24 ++++++++++++------------ block/blk-merge.c | 2 ++ block/blk-mq.c | 2 +- 5 files changed, 43 insertions(+), 17 deletions(-) diff --git a/block/blk-core.c b/block/blk-core.c index ed6271dcc1b16..0c4a4e42ad870 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1421,6 +1421,13 @@ bool blk_update_request(struct request *req, blk_status_t error, req->q->integrity.profile->complete_fn(req, nr_bytes); #endif + /* + * Upper layers may call blk_crypto_evict_key() anytime after the last + * bio_endio(). Therefore, the keyslot must be released before that. + */ + if (blk_crypto_rq_has_keyslot(req) && nr_bytes >= blk_rq_bytes(req)) + __blk_crypto_rq_put_keyslot(req); + if (unlikely(error && !blk_rq_is_passthrough(req) && !(req->rq_flags & RQF_QUIET))) print_req_error(req, error, __func__); diff --git a/block/blk-crypto-internal.h b/block/blk-crypto-internal.h index 0d36aae538d7b..8e08345576203 100644 --- a/block/blk-crypto-internal.h +++ b/block/blk-crypto-internal.h @@ -60,6 +60,11 @@ static inline bool blk_crypto_rq_is_encrypted(struct request *rq) return rq->crypt_ctx; } +static inline bool blk_crypto_rq_has_keyslot(struct request *rq) +{ + return rq->crypt_keyslot; +} + #else /* CONFIG_BLK_INLINE_ENCRYPTION */ static inline bool bio_crypt_rq_ctx_compatible(struct request *rq, @@ -93,6 +98,11 @@ static inline bool blk_crypto_rq_is_encrypted(struct request *rq) return false; } +static inline bool blk_crypto_rq_has_keyslot(struct request *rq) +{ + return false; +} + #endif /* CONFIG_BLK_INLINE_ENCRYPTION */ void __bio_crypt_advance(struct bio *bio, unsigned int bytes); @@ -127,14 +137,21 @@ static inline bool blk_crypto_bio_prep(struct bio **bio_ptr) return true; } -blk_status_t __blk_crypto_init_request(struct request *rq); -static inline blk_status_t blk_crypto_init_request(struct request *rq) +blk_status_t __blk_crypto_rq_get_keyslot(struct request *rq); +static inline blk_status_t blk_crypto_rq_get_keyslot(struct request *rq) { if (blk_crypto_rq_is_encrypted(rq)) - return __blk_crypto_init_request(rq); + return __blk_crypto_rq_get_keyslot(rq); return BLK_STS_OK; } +void __blk_crypto_rq_put_keyslot(struct request *rq); +static inline void blk_crypto_rq_put_keyslot(struct request *rq) +{ + if (blk_crypto_rq_has_keyslot(rq)) + __blk_crypto_rq_put_keyslot(rq); +} + void __blk_crypto_free_request(struct request *rq); static inline void blk_crypto_free_request(struct request *rq) { @@ -173,7 +190,7 @@ static inline blk_status_t blk_crypto_insert_cloned_request(struct request *rq) { if (blk_crypto_rq_is_encrypted(rq)) - return blk_crypto_init_request(rq); + return blk_crypto_rq_get_keyslot(rq); return BLK_STS_OK; } diff --git a/block/blk-crypto.c b/block/blk-crypto.c index 103c2e2d50d67..183d7439cf416 100644 --- a/block/blk-crypto.c +++ b/block/blk-crypto.c @@ -216,26 +216,26 @@ static bool bio_crypt_check_alignment(struct bio *bio) return true; } -blk_status_t __blk_crypto_init_request(struct request *rq) +blk_status_t __blk_crypto_rq_get_keyslot(struct request *rq) { return blk_ksm_get_slot_for_key(rq->q->ksm, rq->crypt_ctx->bc_key, &rq->crypt_keyslot); } -/** - * __blk_crypto_free_request - Uninitialize the crypto fields of a request. - * - * @rq: The request whose crypto fields to uninitialize. - * - * Completely uninitializes the crypto fields of a request. If a keyslot has - * been programmed into some inline encryption hardware, that keyslot is - * released. The rq->crypt_ctx is also freed. - */ -void __blk_crypto_free_request(struct request *rq) +void __blk_crypto_rq_put_keyslot(struct request *rq) { blk_ksm_put_slot(rq->crypt_keyslot); + rq->crypt_keyslot = NULL; +} + +void __blk_crypto_free_request(struct request *rq) +{ + /* The keyslot, if one was needed, should have been released earlier. */ + if (WARN_ON_ONCE(rq->crypt_keyslot)) + __blk_crypto_rq_put_keyslot(rq); + mempool_free(rq->crypt_ctx, bio_crypt_ctx_pool); - blk_crypto_rq_set_defaults(rq); + rq->crypt_ctx = NULL; } /** diff --git a/block/blk-merge.c b/block/blk-merge.c index d1435b6572977..1affc5fd35f0c 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -818,6 +818,8 @@ static struct request *attempt_merge(struct request_queue *q, if (!blk_discard_mergable(req)) elv_merge_requests(q, req, next); + blk_crypto_rq_put_keyslot(next); + /* * 'next' is going away, so update stats accordingly */ diff --git a/block/blk-mq.c b/block/blk-mq.c index 01e281801453d..bbbbcd2c19418 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2228,7 +2228,7 @@ blk_qc_t blk_mq_submit_bio(struct bio *bio) blk_mq_bio_to_request(rq, bio, nr_segs); - ret = blk_crypto_init_request(rq); + ret = blk_crypto_rq_get_keyslot(rq); if (ret != BLK_STS_OK) { bio->bi_status = ret; bio_endio(bio);