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[83.175.106.198]) by smtp.gmail.com with UTF8SMTPSA id e10-20020adffd0a000000b003334675634bsm18528215wrr.29.2023.12.15.03.07.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 15 Dec 2023 03:07:10 -0800 (PST) From: David Gstir To: Mimi Zohar , James Bottomley , Jarkko Sakkinen , Herbert Xu , "David S. Miller" Cc: David Gstir , Shawn Guo , Jonathan Corbet , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , NXP Linux Team , Ahmad Fatoum , sigma star Kernel Team , David Howells , Li Yang , Paul Moore , James Morris , "Serge E. Hallyn" , "Paul E. McKenney" , Randy Dunlap , Catalin Marinas , "Rafael J. Wysocki" , Tejun Heo , "Steven Rostedt (Google)" , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org, keyrings@vger.kernel.org, linux-crypto@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, linux-security-module@vger.kernel.org, Richard Weinberger , David Oberhollenzer Subject: [PATCH v5 1/6] crypto: mxs-dcp: Add support for hardware-bound keys Date: Fri, 15 Dec 2023 12:06:28 +0100 Message-ID: <20231215110639.45522-2-david@sigma-star.at> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20231215110639.45522-1-david@sigma-star.at> References: <20231215110639.45522-1-david@sigma-star.at> Precedence: bulk X-Mailing-List: linux-integrity@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 DCP is capable of performing AES with two hardware-bound keys: - The one-time programmable (OTP) key which is burnt via on-chip fuses - The unique key (UK) which is derived from the OTP key In addition to the two hardware-bound keys, DCP also supports storing keys in 4 dedicated key slots within its secure memory area (internal SRAM). These keys are not stored in main memory and are therefore not directly accessible by the operating system. To use them for AES operations, a one-byte key reference has to supplied with the DCP operation descriptor in the control register. This adds support for using any of these 6 keys through the crypto API via their key reference after they have been set up. The main purpose is to add support for DCP-backed trusted keys. Other use cases are possible too (see similar existing paes implementations), but these should carefully be evaluated as e.g. enabling AF_ALG will give userspace full access to use keys. In scenarios with untrustworthy userspace, this will enable en-/decryption oracles. Co-developed-by: Richard Weinberger Signed-off-by: Richard Weinberger Co-developed-by: David Oberhollenzer Signed-off-by: David Oberhollenzer Signed-off-by: David Gstir Acked-by: Herbert Xu --- drivers/crypto/mxs-dcp.c | 104 ++++++++++++++++++++++++++++++++++----- include/soc/fsl/dcp.h | 17 +++++++ 2 files changed, 110 insertions(+), 11 deletions(-) create mode 100644 include/soc/fsl/dcp.h diff --git a/drivers/crypto/mxs-dcp.c b/drivers/crypto/mxs-dcp.c index f6b7bce0e656..2dc664fb2faf 100644 --- a/drivers/crypto/mxs-dcp.c +++ b/drivers/crypto/mxs-dcp.c @@ -15,6 +15,7 @@ #include #include #include +#include #include #include @@ -101,6 +102,7 @@ struct dcp_async_ctx { struct crypto_skcipher *fallback; unsigned int key_len; uint8_t key[AES_KEYSIZE_128]; + bool key_referenced; }; struct dcp_aes_req_ctx { @@ -155,6 +157,7 @@ static struct dcp *global_sdcp; #define MXS_DCP_CONTROL0_HASH_TERM (1 << 13) #define MXS_DCP_CONTROL0_HASH_INIT (1 << 12) #define MXS_DCP_CONTROL0_PAYLOAD_KEY (1 << 11) +#define MXS_DCP_CONTROL0_OTP_KEY (1 << 10) #define MXS_DCP_CONTROL0_CIPHER_ENCRYPT (1 << 8) #define MXS_DCP_CONTROL0_CIPHER_INIT (1 << 9) #define MXS_DCP_CONTROL0_ENABLE_HASH (1 << 6) @@ -168,6 +171,8 @@ static struct dcp *global_sdcp; #define MXS_DCP_CONTROL1_CIPHER_MODE_ECB (0 << 4) #define MXS_DCP_CONTROL1_CIPHER_SELECT_AES128 (0 << 0) +#define MXS_DCP_CONTROL1_KEY_SELECT_SHIFT 8 + static int mxs_dcp_start_dma(struct dcp_async_ctx *actx) { int dma_err; @@ -224,13 +229,16 @@ static int mxs_dcp_run_aes(struct dcp_async_ctx *actx, struct dcp *sdcp = global_sdcp; struct dcp_dma_desc *desc = &sdcp->coh->desc[actx->chan]; struct dcp_aes_req_ctx *rctx = skcipher_request_ctx(req); + bool key_referenced = actx->key_referenced; int ret; - key_phys = dma_map_single(sdcp->dev, sdcp->coh->aes_key, - 2 * AES_KEYSIZE_128, DMA_TO_DEVICE); - ret = dma_mapping_error(sdcp->dev, key_phys); - if (ret) - return ret; + if (!key_referenced) { + key_phys = dma_map_single(sdcp->dev, sdcp->coh->aes_key, + 2 * AES_KEYSIZE_128, DMA_TO_DEVICE); + ret = dma_mapping_error(sdcp->dev, key_phys); + if (ret) + return ret; + } src_phys = dma_map_single(sdcp->dev, sdcp->coh->aes_in_buf, DCP_BUF_SZ, DMA_TO_DEVICE); @@ -255,8 +263,12 @@ static int mxs_dcp_run_aes(struct dcp_async_ctx *actx, MXS_DCP_CONTROL0_INTERRUPT | MXS_DCP_CONTROL0_ENABLE_CIPHER; - /* Payload contains the key. */ - desc->control0 |= MXS_DCP_CONTROL0_PAYLOAD_KEY; + if (key_referenced) + /* Set OTP key bit to select the key via KEY_SELECT. */ + desc->control0 |= MXS_DCP_CONTROL0_OTP_KEY; + else + /* Payload contains the key. */ + desc->control0 |= MXS_DCP_CONTROL0_PAYLOAD_KEY; if (rctx->enc) desc->control0 |= MXS_DCP_CONTROL0_CIPHER_ENCRYPT; @@ -270,6 +282,9 @@ static int mxs_dcp_run_aes(struct dcp_async_ctx *actx, else desc->control1 |= MXS_DCP_CONTROL1_CIPHER_MODE_CBC; + if (key_referenced) + desc->control1 |= sdcp->coh->aes_key[0] << MXS_DCP_CONTROL1_KEY_SELECT_SHIFT; + desc->next_cmd_addr = 0; desc->source = src_phys; desc->destination = dst_phys; @@ -284,9 +299,9 @@ static int mxs_dcp_run_aes(struct dcp_async_ctx *actx, err_dst: dma_unmap_single(sdcp->dev, src_phys, DCP_BUF_SZ, DMA_TO_DEVICE); err_src: - dma_unmap_single(sdcp->dev, key_phys, 2 * AES_KEYSIZE_128, - DMA_TO_DEVICE); - + if (!key_referenced) + dma_unmap_single(sdcp->dev, key_phys, 2 * AES_KEYSIZE_128, + DMA_TO_DEVICE); return ret; } @@ -453,7 +468,7 @@ static int mxs_dcp_aes_enqueue(struct skcipher_request *req, int enc, int ecb) struct dcp_aes_req_ctx *rctx = skcipher_request_ctx(req); int ret; - if (unlikely(actx->key_len != AES_KEYSIZE_128)) + if (unlikely(actx->key_len != AES_KEYSIZE_128 && !actx->key_referenced)) return mxs_dcp_block_fallback(req, enc); rctx->enc = enc; @@ -500,6 +515,7 @@ static int mxs_dcp_aes_setkey(struct crypto_skcipher *tfm, const u8 *key, * there can still be an operation in progress. */ actx->key_len = len; + actx->key_referenced = false; if (len == AES_KEYSIZE_128) { memcpy(actx->key, key, len); return 0; @@ -516,6 +532,32 @@ static int mxs_dcp_aes_setkey(struct crypto_skcipher *tfm, const u8 *key, return crypto_skcipher_setkey(actx->fallback, key, len); } +static int mxs_dcp_aes_setrefkey(struct crypto_skcipher *tfm, const u8 *key, + unsigned int len) +{ + struct dcp_async_ctx *actx = crypto_skcipher_ctx(tfm); + + if (len != DCP_PAES_KEYSIZE) + return -EINVAL; + + switch (key[0]) { + case DCP_PAES_KEY_SLOT0: + case DCP_PAES_KEY_SLOT1: + case DCP_PAES_KEY_SLOT2: + case DCP_PAES_KEY_SLOT3: + case DCP_PAES_KEY_UNIQUE: + case DCP_PAES_KEY_OTP: + memcpy(actx->key, key, len); + actx->key_len = len; + actx->key_referenced = true; + break; + default: + return -EINVAL; + } + + return 0; +} + static int mxs_dcp_aes_fallback_init_tfm(struct crypto_skcipher *tfm) { const char *name = crypto_tfm_alg_name(crypto_skcipher_tfm(tfm)); @@ -539,6 +581,13 @@ static void mxs_dcp_aes_fallback_exit_tfm(struct crypto_skcipher *tfm) crypto_free_skcipher(actx->fallback); } +static int mxs_dcp_paes_init_tfm(struct crypto_skcipher *tfm) +{ + crypto_skcipher_set_reqsize(tfm, sizeof(struct dcp_aes_req_ctx)); + + return 0; +} + /* * Hashing (SHA1/SHA256) */ @@ -889,6 +938,39 @@ static struct skcipher_alg dcp_aes_algs[] = { .ivsize = AES_BLOCK_SIZE, .init = mxs_dcp_aes_fallback_init_tfm, .exit = mxs_dcp_aes_fallback_exit_tfm, + }, { + .base.cra_name = "ecb(paes)", + .base.cra_driver_name = "ecb-paes-dcp", + .base.cra_priority = 401, + .base.cra_alignmask = 15, + .base.cra_flags = CRYPTO_ALG_ASYNC | CRYPTO_ALG_INTERNAL, + .base.cra_blocksize = AES_BLOCK_SIZE, + .base.cra_ctxsize = sizeof(struct dcp_async_ctx), + .base.cra_module = THIS_MODULE, + + .min_keysize = DCP_PAES_KEYSIZE, + .max_keysize = DCP_PAES_KEYSIZE, + .setkey = mxs_dcp_aes_setrefkey, + .encrypt = mxs_dcp_aes_ecb_encrypt, + .decrypt = mxs_dcp_aes_ecb_decrypt, + .init = mxs_dcp_paes_init_tfm, + }, { + .base.cra_name = "cbc(paes)", + .base.cra_driver_name = "cbc-paes-dcp", + .base.cra_priority = 401, + .base.cra_alignmask = 15, + .base.cra_flags = CRYPTO_ALG_ASYNC | CRYPTO_ALG_INTERNAL, + .base.cra_blocksize = AES_BLOCK_SIZE, + .base.cra_ctxsize = sizeof(struct dcp_async_ctx), + .base.cra_module = THIS_MODULE, + + .min_keysize = DCP_PAES_KEYSIZE, + .max_keysize = DCP_PAES_KEYSIZE, + .setkey = mxs_dcp_aes_setrefkey, + .encrypt = mxs_dcp_aes_cbc_encrypt, + .decrypt = mxs_dcp_aes_cbc_decrypt, + .ivsize = AES_BLOCK_SIZE, + .init = mxs_dcp_paes_init_tfm, }, }; diff --git a/include/soc/fsl/dcp.h b/include/soc/fsl/dcp.h new file mode 100644 index 000000000000..cda89e260c46 --- /dev/null +++ b/include/soc/fsl/dcp.h @@ -0,0 +1,17 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2021 sigma star gmbh + */ + +#ifndef MXS_DCP_H +#define MXS_DCP_H + +#define DCP_PAES_KEYSIZE 1 +#define DCP_PAES_KEY_SLOT0 0x00 +#define DCP_PAES_KEY_SLOT1 0x01 +#define DCP_PAES_KEY_SLOT2 0x02 +#define DCP_PAES_KEY_SLOT3 0x03 +#define DCP_PAES_KEY_UNIQUE 0xfe +#define DCP_PAES_KEY_OTP 0xff + +#endif /* MXS_DCP_H */