From patchwork Fri Mar 3 07:19:57 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 13158380 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 68EF2C7EE32 for ; Fri, 3 Mar 2023 07:23:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229800AbjCCHXf (ORCPT ); Fri, 3 Mar 2023 02:23:35 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55038 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229706AbjCCHXb (ORCPT ); Fri, 3 Mar 2023 02:23:31 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 02D82136E1; Thu, 2 Mar 2023 23:23:29 -0800 (PST) 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 5C81D61770; Fri, 3 Mar 2023 07:23:29 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8F146C433EF; Fri, 3 Mar 2023 07:23:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1677828208; bh=I5Ss6r4/6WUcYMnuwUPr1yRvzmvUpgxCvKLlxau+iVk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=g0sPFUSDKdhlFAE/o+ztKDpP9yNJ8HiV17MFNkniX5LzZUVXDecXNXhDmuyLzNt4n 251QZtHrXpE1Tb02/plnxh0oMJZsrkGBQ0btPP8Px83PrlLoucn/2yZETySBsV1Vbg N+j7i9u3Xnc5chELVeUyPNsgi6fhSMTLyvg+YTqXjLyM8ZVQgosb+zGES10Hb94lk0 xK/iGs4HmBnexZ8l7MPvBMcYloQau+mi6/6hVO6IYZfEDoqJ0HrRykrjfLpk/dJsAO PGsu19sHODANG0GpbBHlTrlaR21tLEYzfxe6727AmsyoYHgkVt4stbzGiMUxiXfaLG d6izMsxDt6F9w== From: Eric Biggers To: linux-block@vger.kernel.org, Jens Axboe Cc: linux-fscrypt@vger.kernel.org, Nathan Huckleberry , stable@vger.kernel.org Subject: [PATCH 1/3] blk-mq: release crypto keyslot before reporting I/O complete Date: Thu, 2 Mar 2023 23:19:57 -0800 Message-Id: <20230303071959.144604-2-ebiggers@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230303071959.144604-1-ebiggers@kernel.org> References: <20230303071959.144604-1-ebiggers@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org From: Eric Biggers 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 Signed-off-by: Eric Biggers Reviewed-by: Nathan Huckleberry --- block/blk-crypto-internal.h | 15 +++++++++++---- block/blk-crypto.c | 24 ++++++++++++------------ block/blk-mq.c | 15 ++++++++++++++- 3 files changed, 37 insertions(+), 17 deletions(-) diff --git a/block/blk-crypto-internal.h b/block/blk-crypto-internal.h index a8cdaf26851e1..73609902349b6 100644 --- a/block/blk-crypto-internal.h +++ b/block/blk-crypto-internal.h @@ -153,14 +153,21 @@ 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_is_encrypted(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) { @@ -199,7 +206,7 @@ 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 45378586151f7..8e5612364c48c 100644 --- a/block/blk-crypto.c +++ b/block/blk-crypto.c @@ -224,27 +224,27 @@ 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_crypto_get_keyslot(rq->q->crypto_profile, 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_crypto_put_keyslot(rq->crypt_keyslot); + rq->crypt_keyslot = NULL; +} + +void __blk_crypto_free_request(struct request *rq) +{ mempool_free(rq->crypt_ctx, bio_crypt_ctx_pool); - blk_crypto_rq_set_defaults(rq); + rq->crypt_ctx = NULL; + + /* The keyslot, if one was needed, should have been released earlier. */ + if (WARN_ON_ONCE(rq->crypt_keyslot)) + __blk_crypto_rq_put_keyslot(rq); } /** diff --git a/block/blk-mq.c b/block/blk-mq.c index d3494a796ba80..738e81f518227 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -840,6 +840,12 @@ static void blk_complete_request(struct request *req) req->q->integrity.profile->complete_fn(req, total_bytes); #endif + /* + * Upper layers may call blk_crypto_evict_key() anytime after the last + * bio_endio(). Therefore, the keyslot must be released before that. + */ + blk_crypto_rq_put_keyslot(req); + blk_account_io_completion(req, total_bytes); do { @@ -905,6 +911,13 @@ 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_is_encrypted(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)) && !test_bit(GD_DEAD, &req->q->disk->state)) { @@ -2967,7 +2980,7 @@ void 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);