On Thu Mar 7, 2024 at 5:38 PM EET, David Gstir wrote: > DCP (Data Co-Processor) is able to derive private keys for a fused > random seed, which can be referenced by handle but not accessed by > the CPU. Similarly, DCP is able to store arbitrary keys in four > dedicated key slots located in its secure memory area (internal SRAM). > These keys can be used to perform AES encryption. > > Expose these derived keys and key slots through the crypto API via their > handle. The main purpose is to add 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 <richard@xxxxxx> > Signed-off-by: Richard Weinberger <richard@xxxxxx> > Co-developed-by: David Oberhollenzer <david.oberhollenzer@xxxxxxxxxxxxx> > Signed-off-by: David Oberhollenzer <david.oberhollenzer@xxxxxxxxxxxxx> > Signed-off-by: David Gstir <david@xxxxxxxxxxxxx> > Acked-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> > --- > drivers/crypto/mxs-dcp.c | 104 ++++++++++++++++++++++++++++++++++----- > include/soc/fsl/dcp.h | 20 ++++++++ > 2 files changed, 113 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 2b3ebe0db3a6..057d73c370b7 100644 > --- a/drivers/crypto/mxs-dcp.c > +++ b/drivers/crypto/mxs-dcp.c > @@ -15,6 +15,7 @@ > #include <linux/platform_device.h> > #include <linux/stmp_device.h> > #include <linux/clk.h> > +#include <soc/fsl/dcp.h> > > #include <crypto/aes.h> > #include <crypto/sha1.h> > @@ -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..3ec335d8ca8b > --- /dev/null > +++ b/include/soc/fsl/dcp.h > @@ -0,0 +1,20 @@ > +/* SPDX-License-Identifier: GPL-2.0-only */ > +/* > + * Copyright (C) 2021 sigma star gmbh > + * > + * Specifies paes key slot handles for NXP's DCP (Data Co-Processor) to be used > + * with the crypto_skcipher_setkey(). > + */ > + > +#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 */ Looks to good enough to me: Reviewed-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx> BR, Jarkko