From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from list by lists.gnu.org with archive (Exim 4.90_1) id 1klEas-00073P-TU for mharc-grub-devel@gnu.org; Fri, 04 Dec 2020 12:10:13 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:34946) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1klEab-0006zI-O1 for grub-devel@gnu.org; Fri, 04 Dec 2020 12:09:54 -0500 Received: from mail-qt1-x844.google.com ([2607:f8b0:4864:20::844]:40983) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1klEZz-00067p-Pp for grub-devel@gnu.org; Fri, 04 Dec 2020 12:09:30 -0500 Received: by mail-qt1-x844.google.com with SMTP id l7so4402059qtp.8 for ; Fri, 04 Dec 2020 09:07:20 -0800 (PST) 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=EJ7uPsQW4YgRIdPshn0sOFRs3OyFl2iu4ZfXzWW2x3U=; b=qdpSiN7hY25w8+VREdONUfpKrznohf/RPuswv+WVl0T3IFGYbykgH927sKhoqP16hZ V19YcZGEIkMJumq1x6kXwS/FxQe/p7ThE2mbpEjZwIWPZ//SZORfejmaIHIWN+NpGW1y JhzTfB7+Har8IBrsbiDUHg7pJuD1rzVeiF6Qz+rghqp5HBgOiwbgpzHR3uRtRJ2qDkqC DRH/gMpnU1plGPoFAe5LgTwI2rKcD+EhAs6OZdPVznM7VXF/N0XcdPy083lbxkiE+jFo QGwf+aDFUOQB+8l9GwhP6dO+T+4fmbvttMCm3Aa6OlM2RlCfuRHPhgwaVjaQr/SdaX+e v9NQ== 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=EJ7uPsQW4YgRIdPshn0sOFRs3OyFl2iu4ZfXzWW2x3U=; b=kskL/ojY8vElyXlDSEIOwtStc1ND/qGWJHN00EXTumb3UZN8QPLgHOBAc4A6sHunto 2KC+9DFtFcWUzPIvwoM+rm/6l3cPH7xJOWPza1nJFXFGnATWEMUVtD6woZpAquVxbec+ R48lrBhcJ2kMR7037yNfaHD9PUPSMkOaerBxHxbU/SWKh4J+tBZxVyNEYLeEYYhrEA79 wUXDH0wWEQkbDKHSCURNfCvElS2j98lYjYkcTXVeMEfJ2kfpptZkUEMHMnJHhrPwmNUP M+Yb8r4jpbVzFu6baxA7+kduntMPIZS9fxOlG2AGubRZoidvj/OkiStySWZmdkPkwKcU ygaA== X-Gm-Message-State: AOAM532RquKPhDaCoYbhNiupx+etkZy7nr5Z7TYH2Ihsd1Arg91puq5S AdCFQwghkqHrn1/zu6KpjYUJM0wbyb6RfQ== X-Google-Smtp-Source: ABdhPJz7Fp+08ESPWiSj38T4d++0ivG3vCKvJVvdDqTUoGnUsAJyNIqYqueP7qi1fPDDlvoNP2uPHw== X-Received: by 2002:a02:ce8a:: with SMTP id y10mr7275670jaq.102.1607100265629; Fri, 04 Dec 2020 08:44:25 -0800 (PST) Received: from localhost.localdomain ([136.49.211.192]) by smtp.gmail.com with ESMTPSA id w3sm1754909iol.9.2020.12.04.08.44.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 04 Dec 2020 08:44:25 -0800 (PST) From: Glenn Washburn To: grub-devel@gnu.org Cc: Patrick Steinhardt , Daniel Kiper , Glenn Washburn , Daniel Kiper Subject: [PATCH v7 11/17] cryptodisk: Properly handle non-512 byte sized sectors Date: Fri, 4 Dec 2020 10:43:40 -0600 Message-Id: <1fe9c38ed3a31716c81581eac6d6d7ce12a2c7d7.1607098915.git.development@efficientek.com> 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::844; envelope-from=development@efficientek.com; helo=mail-qt1-x844.google.com 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=unavailable 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: Fri, 04 Dec 2020 17:09:57 -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. Reviewed-by: Daniel Kiper Signed-off-by: Glenn Washburn --- grub-core/disk/cryptodisk.c | 55 +++++++++++++++++++++++-------------- grub-core/disk/luks.c | 5 ++-- grub-core/disk/luks2.c | 7 ++++- include/grub/cryptodisk.h | 8 +++++- 4 files changed, 50 insertions(+), 25 deletions(-) diff --git a/grub-core/disk/cryptodisk.c b/grub-core/disk/cryptodisk.c index 5aa0c4720..b62835acc 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)); @@ -281,15 +282,27 @@ grub_cryptodisk_endecrypt (struct grub_cryptodisk *dev, } break; case GRUB_CRYPTODISK_MODE_IV_PLAIN64: - iv[1] = grub_cpu_to_le32 (sector >> GRUB_TYPE_BITS (iv[0])); - /* FALLTHROUGH */ case GRUB_CRYPTODISK_MODE_IV_PLAIN: - iv[0] = grub_cpu_to_le32 (sector & GRUB_TYPE_U_MAX (iv[0])); + /* + * 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; + + iv64 = grub_cpu_to_le64 (sector << (log_sector_size + - GRUB_CRYPTODISK_IV_LOG_SIZE)); + grub_set_unaligned64 (iv, iv64); + if (dev->mode_iv == GRUB_CRYPTODISK_MODE_IV_PLAIN) + iv[1] = 0; + } break; case GRUB_CRYPTODISK_MODE_IV_BYTECOUNT64: + /* The IV is the 64 bit byte offset of the sector. */ iv[1] = grub_cpu_to_le32 (sector >> (GRUB_TYPE_BITS (iv[1]) - - dev->log_sector_size)); - iv[0] = grub_cpu_to_le32 ((sector << dev->log_sector_size) + - log_sector_size)); + iv[0] = grub_cpu_to_le32 ((sector << log_sector_size) & GRUB_TYPE_U_MAX (iv[0])); break; case GRUB_CRYPTODISK_MODE_IV_BENBI: @@ -312,10 +325,10 @@ 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; @@ -323,10 +336,10 @@ 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; @@ -338,7 +351,7 @@ 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, @@ -369,11 +382,11 @@ 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); @@ -382,10 +395,10 @@ 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; @@ -400,9 +413,9 @@ 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 @@ -767,7 +780,7 @@ 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); } @@ -808,7 +821,7 @@ 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 5fc79d880..13103ea6a 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_sectors = grub_be_to_cpu32 (header.payloadOffset); newdev->source_disk = NULL; - newdev->log_sector_size = 9; + newdev->log_sector_size = GRUB_LUKS1_LOG_SECTOR_SIZE; newdev->total_sectors = grub_disk_native_sectors (disk) - newdev->offset_sectors; 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, + GRUB_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 bdf40768b..de2e70796 100644 --- a/grub-core/disk/luks2.c +++ b/grub-core/disk/luks2.c @@ -504,7 +504,12 @@ 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, + GRUB_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 c9bf7597a..938912cf3 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 GRUB_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) @@ -144,7 +150,7 @@ 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