From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from list by lists.gnu.org with archive (Exim 4.90_1) id 1kOqRs-0007cc-Tl for mharc-grub-devel@gnu.org; Sat, 03 Oct 2020 18:56:19 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:54750) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kOqRo-0007aV-6C for grub-devel@gnu.org; Sat, 03 Oct 2020 18:56:13 -0400 Received: from mail-ot1-x342.google.com ([2607:f8b0:4864:20::342]:39935) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1kOqRj-0000Fh-G9 for grub-devel@gnu.org; Sat, 03 Oct 2020 18:56:11 -0400 Received: by mail-ot1-x342.google.com with SMTP id u25so5104747otq.6 for ; Sat, 03 Oct 2020 15:56:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=efficientek-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=NkN+aS6kML4F69nFjXzwuStgwjiEJftvm+nBFFX2liM=; b=ul1aXC2Rac0FJdmN1TQZiP5nmlt/xQGBcpal0E/cieYCKflDI+qCPUiDDu78djVZ3p c6kq8JhuVw3NTsvYjbH4eoLE638qLoUQlNb05n/zlFpBtYC1B5Bjj51lSqW2vxFExyI4 1erEze0uGNlk2wTuo/Iy8S9V3GAAwO/zH9nCxPO4yhySTZbkACrDZharCZq+LOXnUAeq 3qfhTQWP/CGBzFSSkRfVOVHOs5TBEeWvEO9pPWk2SbOTrUqabkANwloWfCjkptSuY3Wt UcdUlU0KBop3PLvWfSQnZ0XWzllQ7qlmgYYz1ymV5PGRTOiNN2mABsRhx+EQ2YGqYzmY usvA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=NkN+aS6kML4F69nFjXzwuStgwjiEJftvm+nBFFX2liM=; b=E96g7XdBr5KnUW8Uv8tsR5+Do0D+Hp+wVL+drqVaCPRo34GrlPcOQa5aGnBKQBe9ND o952WaqPyD6LHJMK01J0J7zJniIipNOvg6G4YtxEpmXnmS9eDtDe2XD6hXCzyzVSKmS7 T9CgfzC26HaQWpLLgZwahQiyvxQ+4QyVBdJoql7tmRDhInzg4HHvIYDSo9StCDliFGrv L6DLQqnJGPu3l0GbtmchfvRPofzFhn6iBk1iiUGwBjnANUcq3jXnGBrX9u0vrwXLhqxY ojutJrlnR2BCCdMdNez1ZzTbbUb/lrHIe4ygQ10ch9MxWxcVaaD2fd7xMxpPDf9yl2nx o+YA== X-Gm-Message-State: AOAM5324cEAC/1IOmGlXdVT2/Q5WjUmkKnlEigrDuFdmn1QBNLmwqdd8 hdTGoox/geNuxbqgSOpKwOQQx07JOHdFjA== X-Google-Smtp-Source: ABdhPJyk0EneQyPx8yxwfQ8iWL6eQgR57IaDwdUZByEQa/Kc5KhxedvcbJcAnTb+bPUK+S+izTsHRw== X-Received: by 2002:a05:6830:1e26:: with SMTP id t6mr5581096otr.318.1601765766060; Sat, 03 Oct 2020 15:56:06 -0700 (PDT) Received: from crass-HP-ZBook-15-G2.lan ([136.49.44.103]) by smtp.gmail.com with ESMTPSA id d17sm1524580oth.73.2020.10.03.15.56.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 03 Oct 2020 15:56:05 -0700 (PDT) From: Glenn Washburn To: grub-devel@gnu.org Cc: Daniel Kiper , Patrick Steinhardt , Glenn Washburn Subject: [PATCH v2 06/10] cryptodisk: Properly handle non-512 byte sized sectors. Date: Sat, 3 Oct 2020 17:55:30 -0500 Message-Id: X-Mailer: git-send-email 2.27.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2607:f8b0:4864:20::342; envelope-from=development@efficientek.com; helo=mail-ot1-x342.google.com X-detected-operating-system: by eggs.gnu.org: No matching host in p0f cache. That's all we know. X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: grub-devel@gnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: The development of GNU GRUB List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 03 Oct 2020 22:56:14 -0000 By default, dm-crypt internally uses an IV that corresponds to 512-byte sectors, even when a larger sector size is specified. What this means is that when using a larger sector size, the IV is incremented every sector. However, the amount the IV is incremented is the number of 512 byte blocks in a sector (ie 8 for 4K sectors). Confusingly the IV does not corespond to the number of, for example, 4K sectors. So each 512 byte cipher block in a sector will be encrypted with the same IV and the IV will be incremented afterwards by the number of 512 byte cipher blocks in the sector. There are some encryption utilities which do it the intuitive way and have the IV equal to the sector number regardless of sector size (ie. the fifth sector would have an IV of 4 for each cipher block). And this is supported by dm-crypt with the iv_large_sectors option and also cryptsetup as of 2.3.3 with the --iv-large-sectors, though not with LUKS headers (only with --type plain). However, support for this has not been included as grub does not support plain devices right now. One gotcha here is that the encrypted split keys are encrypted with a hard- coded 512-byte sector size. So even if your data is encrypted with 4K sector sizes, the split key encrypted area must be decrypted with a block size of 512 (ie the IV increments every 512 bytes). This made these changes less aestetically pleasing than desired. Signed-off-by: Glenn Washburn --- grub-core/disk/cryptodisk.c | 52 ++++++++++++++++++++++--------------- grub-core/disk/luks.c | 5 ++-- grub-core/disk/luks2.c | 7 ++++- include/grub/cryptodisk.h | 8 +++++- 4 files changed, 47 insertions(+), 25 deletions(-) diff --git a/grub-core/disk/cryptodisk.c b/grub-core/disk/cryptodisk.c index a3d672f68..623f0f396 100644 --- a/grub-core/disk/cryptodisk.c +++ b/grub-core/disk/cryptodisk.c @@ -224,7 +224,8 @@ lrw_xor (const struct lrw_sector *sec, static gcry_err_code_t grub_cryptodisk_endecrypt (struct grub_cryptodisk *dev, grub_uint8_t * data, grub_size_t len, - grub_disk_addr_t sector, int do_encrypt) + grub_disk_addr_t sector, grub_size_t log_sector_size, + int do_encrypt) { grub_size_t i; gcry_err_code_t err; @@ -237,7 +238,7 @@ grub_cryptodisk_endecrypt (struct grub_cryptodisk *dev, return (do_encrypt ? grub_crypto_ecb_encrypt (dev->cipher, data, data, len) : grub_crypto_ecb_decrypt (dev->cipher, data, data, len)); - for (i = 0; i < len; i += (1U << dev->log_sector_size)) + for (i = 0; i < len; i += (1U << log_sector_size)) { grub_size_t sz = ((dev->cipher->cipher->blocksize + sizeof (grub_uint32_t) - 1) @@ -270,7 +271,7 @@ grub_cryptodisk_endecrypt (struct grub_cryptodisk *dev, if (!ctx) return GPG_ERR_OUT_OF_MEMORY; - tmp = grub_cpu_to_le64 (sector << dev->log_sector_size); + tmp = grub_cpu_to_le64 (sector << log_sector_size); dev->iv_hash->init (ctx); dev->iv_hash->write (ctx, dev->iv_prefix, dev->iv_prefix_len); dev->iv_hash->write (ctx, &tmp, sizeof (tmp)); @@ -281,14 +282,23 @@ grub_cryptodisk_endecrypt (struct grub_cryptodisk *dev, } break; case GRUB_CRYPTODISK_MODE_IV_PLAIN64: - iv[1] = grub_cpu_to_le32 (sector >> 32); - /* FALLTHROUGH */ case GRUB_CRYPTODISK_MODE_IV_PLAIN: - iv[0] = grub_cpu_to_le32 (sector & 0xFFFFFFFF); + /* + * The IV is a 32 or 64 bit value of the dm-crypt native sector + * number. If using 32 bit IV mode, zero out the most significant + * 32 bits. + */ + { + grub_uint64_t *iv64 = (grub_uint64_t *)iv; + *iv64 = grub_cpu_to_le64 (sector << (log_sector_size + - GRUB_CRYPTODISK_IV_LOG_SIZE)); + if (dev->mode_iv == GRUB_CRYPTODISK_MODE_IV_PLAIN) + iv[1] = 0; + } break; case GRUB_CRYPTODISK_MODE_IV_BYTECOUNT64: - iv[1] = grub_cpu_to_le32 (sector >> (32 - dev->log_sector_size)); - iv[0] = grub_cpu_to_le32 ((sector << dev->log_sector_size) + iv[1] = grub_cpu_to_le32 (sector >> (32 - log_sector_size)); + iv[0] = grub_cpu_to_le32 ((sector << log_sector_size) & 0xFFFFFFFF); break; case GRUB_CRYPTODISK_MODE_IV_BENBI: @@ -311,10 +321,10 @@ grub_cryptodisk_endecrypt (struct grub_cryptodisk *dev, case GRUB_CRYPTODISK_MODE_CBC: if (do_encrypt) err = grub_crypto_cbc_encrypt (dev->cipher, data + i, data + i, - (1U << dev->log_sector_size), iv); + (1U << log_sector_size), iv); else err = grub_crypto_cbc_decrypt (dev->cipher, data + i, data + i, - (1U << dev->log_sector_size), iv); + (1U << log_sector_size), iv); if (err) return err; break; @@ -322,10 +332,10 @@ grub_cryptodisk_endecrypt (struct grub_cryptodisk *dev, case GRUB_CRYPTODISK_MODE_PCBC: if (do_encrypt) err = grub_crypto_pcbc_encrypt (dev->cipher, data + i, data + i, - (1U << dev->log_sector_size), iv); + (1U << log_sector_size), iv); else err = grub_crypto_pcbc_decrypt (dev->cipher, data + i, data + i, - (1U << dev->log_sector_size), iv); + (1U << log_sector_size), iv); if (err) return err; break; @@ -337,7 +347,7 @@ grub_cryptodisk_endecrypt (struct grub_cryptodisk *dev, if (err) return err; - for (j = 0; j < (1U << dev->log_sector_size); + for (j = 0; j < (1U << log_sector_size); j += dev->cipher->cipher->blocksize) { grub_crypto_xor (data + i + j, data + i + j, iv, @@ -368,11 +378,11 @@ grub_cryptodisk_endecrypt (struct grub_cryptodisk *dev, if (do_encrypt) err = grub_crypto_ecb_encrypt (dev->cipher, data + i, data + i, - (1U << dev->log_sector_size)); + (1U << log_sector_size)); else err = grub_crypto_ecb_decrypt (dev->cipher, data + i, data + i, - (1U << dev->log_sector_size)); + (1U << log_sector_size)); if (err) return err; lrw_xor (&sec, dev, data + i); @@ -381,10 +391,10 @@ grub_cryptodisk_endecrypt (struct grub_cryptodisk *dev, case GRUB_CRYPTODISK_MODE_ECB: if (do_encrypt) err = grub_crypto_ecb_encrypt (dev->cipher, data + i, data + i, - (1U << dev->log_sector_size)); + (1U << log_sector_size)); else err = grub_crypto_ecb_decrypt (dev->cipher, data + i, data + i, - (1U << dev->log_sector_size)); + (1U << log_sector_size)); if (err) return err; break; @@ -399,9 +409,9 @@ grub_cryptodisk_endecrypt (struct grub_cryptodisk *dev, gcry_err_code_t grub_cryptodisk_decrypt (struct grub_cryptodisk *dev, grub_uint8_t * data, grub_size_t len, - grub_disk_addr_t sector) + grub_disk_addr_t sector, grub_size_t log_sector_size) { - return grub_cryptodisk_endecrypt (dev, data, len, sector, 0); + return grub_cryptodisk_endecrypt (dev, data, len, sector, log_sector_size, 0); } grub_err_t @@ -766,7 +776,7 @@ grub_cryptodisk_read (grub_disk_t disk, grub_disk_addr_t sector, } gcry_err = grub_cryptodisk_endecrypt (dev, (grub_uint8_t *) buf, size << disk->log_sector_size, - sector, 0); + sector, dev->log_sector_size, 0); return grub_crypto_gcry_error (gcry_err); } @@ -807,7 +817,7 @@ grub_cryptodisk_write (grub_disk_t disk, grub_disk_addr_t sector, gcry_err = grub_cryptodisk_endecrypt (dev, (grub_uint8_t *) tmp, size << disk->log_sector_size, - sector, 1); + sector, disk->log_sector_size, 1); if (gcry_err) { grub_free (tmp); diff --git a/grub-core/disk/luks.c b/grub-core/disk/luks.c index 59702067a..20cc20b9b 100644 --- a/grub-core/disk/luks.c +++ b/grub-core/disk/luks.c @@ -124,7 +124,7 @@ configure_ciphers (grub_disk_t disk, const char *check_uuid, return NULL; newdev->offset = grub_be_to_cpu32 (header.payloadOffset); newdev->source_disk = NULL; - newdev->log_sector_size = 9; + newdev->log_sector_size = LUKS1_LOG_SECTOR_SIZE; newdev->total_length = grub_disk_get_size (disk) - newdev->offset; grub_memcpy (newdev->uuid, uuid, sizeof (uuid)); newdev->modname = "luks"; @@ -247,7 +247,8 @@ luks_recover_key (grub_disk_t source, return err; } - gcry_err = grub_cryptodisk_decrypt (dev, split_key, length, 0); + gcry_err = grub_cryptodisk_decrypt (dev, split_key, length, 0, + LUKS1_LOG_SECTOR_SIZE); if (gcry_err) { grub_free (split_key); diff --git a/grub-core/disk/luks2.c b/grub-core/disk/luks2.c index 9f7d6e12b..b7d3b425a 100644 --- a/grub-core/disk/luks2.c +++ b/grub-core/disk/luks2.c @@ -499,7 +499,12 @@ luks2_decrypt_key (grub_uint8_t *out_key, goto err; } - gcry_ret = grub_cryptodisk_decrypt (crypt, split_key, k->area.size, 0); + /* + * The key slots area is always encrypted in 512-byte sectors, + * regardless of encrypted data sector size. + */ + gcry_ret = grub_cryptodisk_decrypt (crypt, split_key, k->area.size, 0, + LUKS1_LOG_SECTOR_SIZE); if (gcry_ret) { ret = grub_crypto_gcry_error (gcry_ret); diff --git a/include/grub/cryptodisk.h b/include/grub/cryptodisk.h index e1b21e785..006f3ec49 100644 --- a/include/grub/cryptodisk.h +++ b/include/grub/cryptodisk.h @@ -48,6 +48,12 @@ typedef enum #define GRUB_CRYPTODISK_MAX_UUID_LENGTH 71 +/* LUKS1 specification defines the block size to always be 512 bytes. */ +#define LUKS1_LOG_SECTOR_SIZE 9 + +/* By default dm-crypt increments the IV every 512 bytes. */ +#define GRUB_CRYPTODISK_IV_LOG_SIZE 9 + #define GRUB_CRYPTODISK_GF_LOG_SIZE 7 #define GRUB_CRYPTODISK_GF_SIZE (1U << GRUB_CRYPTODISK_GF_LOG_SIZE) #define GRUB_CRYPTODISK_GF_LOG_BYTES (GRUB_CRYPTODISK_GF_LOG_SIZE - 3) @@ -139,7 +145,7 @@ grub_cryptodisk_setkey (grub_cryptodisk_t dev, gcry_err_code_t grub_cryptodisk_decrypt (struct grub_cryptodisk *dev, grub_uint8_t * data, grub_size_t len, - grub_disk_addr_t sector); + grub_disk_addr_t sector, grub_size_t log_sector_size); grub_err_t grub_cryptodisk_insert (grub_cryptodisk_t newdev, const char *name, grub_disk_t source); -- 2.27.0