From 65c4c93caaf1a9fca2855942e338530967162d25 Mon Sep 17 00:00:00 2001 From: Lukas Wunner Date: Tue, 10 Sep 2024 16:30:12 +0200 Subject: crypto: sig - Introduce sig_alg backend Commit 6cb8815f41a9 ("crypto: sig - Add interface for sign/verify") began a transition of asymmetric sign/verify operations from crypto_akcipher to a new crypto_sig frontend. Internally, the crypto_sig frontend still uses akcipher_alg as backend, however: "The link between sig and akcipher is meant to be temporary. The plan is to create a new low-level API for sig and then migrate the signature code over to that from akcipher." https://lore.kernel.org/r/ZrG6w9wsb-iiLZIF@gondor.apana.org.au/ "having a separate alg for sig is definitely where we want to be since there is very little that the two types actually share." https://lore.kernel.org/r/ZrHlpz4qnre0zWJO@gondor.apana.org.au/ Take the next step of that migration and augment the crypto_sig frontend with a sig_alg backend to which all algorithms can be moved. During the migration, there will briefly be signature algorithms that are still based on crypto_akcipher, whilst others are already based on crypto_sig. Allow for that by building a fork into crypto_sig_*() API calls (i.e. crypto_sig_maxsize() and friends) such that one of the two backends is selected based on the transform's cra_type. Signed-off-by: Lukas Wunner Signed-off-by: Herbert Xu --- include/uapi/linux/cryptouser.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'include/uapi') diff --git a/include/uapi/linux/cryptouser.h b/include/uapi/linux/cryptouser.h index 20a6c0fc149e..db05e0419972 100644 --- a/include/uapi/linux/cryptouser.h +++ b/include/uapi/linux/cryptouser.h @@ -64,6 +64,7 @@ enum crypto_attr_type_t { CRYPTOCFGA_STAT_AKCIPHER, /* No longer supported, do not use. */ CRYPTOCFGA_STAT_KPP, /* No longer supported, do not use. */ CRYPTOCFGA_STAT_ACOMP, /* No longer supported, do not use. */ + CRYPTOCFGA_REPORT_SIG, /* struct crypto_report_sig */ __CRYPTOCFGA_MAX #define CRYPTOCFGA_MAX (__CRYPTOCFGA_MAX - 1) @@ -207,6 +208,10 @@ struct crypto_report_acomp { char type[CRYPTO_MAX_NAME]; }; +struct crypto_report_sig { + char type[CRYPTO_MAX_NAME]; +}; + #define CRYPTO_REPORT_MAXSIZE (sizeof(struct crypto_user_alg) + \ sizeof(struct crypto_report_blkcipher)) -- cgit v1.2.3 From 5b553e06b3215fa97d222ebddc2bc964f1824c5b Mon Sep 17 00:00:00 2001 From: Lukas Wunner Date: Tue, 10 Sep 2024 16:30:19 +0200 Subject: crypto: virtio - Drop sign/verify operations The virtio crypto driver exposes akcipher sign/verify operations in a user space ABI. This blocks removal of sign/verify from akcipher_alg. Herbert opines: "I would say that this is something that we can break. Breaking it is no different to running virtio on a host that does not support these algorithms. After all, a software implementation must always be present. I deliberately left akcipher out of crypto_user because the API is still in flux. We should not let virtio constrain ourselves." https://lore.kernel.org/all/ZtqoNAgcnXnrYhZZ@gondor.apana.org.au/ "I would remove virtio akcipher support in its entirety. This API was never meant to be exposed outside of the kernel." https://lore.kernel.org/all/Ztqql_gqgZiMW8zz@gondor.apana.org.au/ Drop sign/verify support from virtio crypto. There's no strong reason to also remove encrypt/decrypt support, so keep it. A key selling point of virtio crypto is to allow guest access to crypto accelerators on the host. So far the only akcipher algorithm supported by virtio crypto is RSA. Dropping sign/verify merely means that the PKCS#1 padding is now always generated or verified inside the guest, but the actual signature generation/verification (which is an RSA decrypt/encrypt operation) may still use an accelerator on the host. Generating or verifying the PKCS#1 padding is cheap, so a hardware accelerator won't be of much help there. Which begs the question whether virtio crypto support for sign/verify makes sense at all. It would make sense for the sign operation if the host has a security chip to store asymmetric private keys. But the kernel doesn't even have an asymmetric_key_subtype yet for hardware-based private keys. There's at least one rudimentary driver for such chips (atmel-ecc.c for ATECC508A), but it doesn't implement the sign operation. The kernel would first have to grow support for a hardware asymmetric_key_subtype and at least one driver implementing the sign operation before exposure to guests via virtio makes sense. Signed-off-by: Lukas Wunner Signed-off-by: Herbert Xu --- .../crypto/virtio/virtio_crypto_akcipher_algs.c | 65 +++++++--------------- include/uapi/linux/virtio_crypto.h | 1 + 2 files changed, 22 insertions(+), 44 deletions(-) (limited to 'include/uapi') diff --git a/drivers/crypto/virtio/virtio_crypto_akcipher_algs.c b/drivers/crypto/virtio/virtio_crypto_akcipher_algs.c index cb92b7fa99c6..48fee07b7e51 100644 --- a/drivers/crypto/virtio/virtio_crypto_akcipher_algs.c +++ b/drivers/crypto/virtio/virtio_crypto_akcipher_algs.c @@ -83,23 +83,16 @@ static void virtio_crypto_dataq_akcipher_callback(struct virtio_crypto_request * case VIRTIO_CRYPTO_BADMSG: error = -EBADMSG; break; - - case VIRTIO_CRYPTO_KEY_REJECTED: - error = -EKEYREJECTED; - break; - default: error = -EIO; break; } akcipher_req = vc_akcipher_req->akcipher_req; - if (vc_akcipher_req->opcode != VIRTIO_CRYPTO_AKCIPHER_VERIFY) { - /* actuall length maybe less than dst buffer */ - akcipher_req->dst_len = len - sizeof(vc_req->status); - sg_copy_from_buffer(akcipher_req->dst, sg_nents(akcipher_req->dst), - vc_akcipher_req->dst_buf, akcipher_req->dst_len); - } + /* actual length maybe less than dst buffer */ + akcipher_req->dst_len = len - sizeof(vc_req->status); + sg_copy_from_buffer(akcipher_req->dst, sg_nents(akcipher_req->dst), + vc_akcipher_req->dst_buf, akcipher_req->dst_len); virtio_crypto_akcipher_finalize_req(vc_akcipher_req, akcipher_req, error); } @@ -230,36 +223,27 @@ static int __virtio_crypto_akcipher_do_req(struct virtio_crypto_akcipher_request int node = dev_to_node(&vcrypto->vdev->dev); unsigned long flags; int ret; - bool verify = vc_akcipher_req->opcode == VIRTIO_CRYPTO_AKCIPHER_VERIFY; - unsigned int src_len = verify ? req->src_len + req->dst_len : req->src_len; /* out header */ sg_init_one(&outhdr_sg, req_data, sizeof(*req_data)); sgs[num_out++] = &outhdr_sg; /* src data */ - src_buf = kcalloc_node(src_len, 1, GFP_KERNEL, node); + src_buf = kcalloc_node(req->src_len, 1, GFP_KERNEL, node); if (!src_buf) return -ENOMEM; - if (verify) { - /* for verify operation, both src and dst data work as OUT direction */ - sg_copy_to_buffer(req->src, sg_nents(req->src), src_buf, src_len); - sg_init_one(&srcdata_sg, src_buf, src_len); - sgs[num_out++] = &srcdata_sg; - } else { - sg_copy_to_buffer(req->src, sg_nents(req->src), src_buf, src_len); - sg_init_one(&srcdata_sg, src_buf, src_len); - sgs[num_out++] = &srcdata_sg; + sg_copy_to_buffer(req->src, sg_nents(req->src), src_buf, req->src_len); + sg_init_one(&srcdata_sg, src_buf, req->src_len); + sgs[num_out++] = &srcdata_sg; - /* dst data */ - dst_buf = kcalloc_node(req->dst_len, 1, GFP_KERNEL, node); - if (!dst_buf) - goto free_src; + /* dst data */ + dst_buf = kcalloc_node(req->dst_len, 1, GFP_KERNEL, node); + if (!dst_buf) + goto free_src; - sg_init_one(&dstdata_sg, dst_buf, req->dst_len); - sgs[num_out + num_in++] = &dstdata_sg; - } + sg_init_one(&dstdata_sg, dst_buf, req->dst_len); + sgs[num_out + num_in++] = &dstdata_sg; vc_akcipher_req->src_buf = src_buf; vc_akcipher_req->dst_buf = dst_buf; @@ -352,16 +336,6 @@ static int virtio_crypto_rsa_decrypt(struct akcipher_request *req) return virtio_crypto_rsa_req(req, VIRTIO_CRYPTO_AKCIPHER_DECRYPT); } -static int virtio_crypto_rsa_sign(struct akcipher_request *req) -{ - return virtio_crypto_rsa_req(req, VIRTIO_CRYPTO_AKCIPHER_SIGN); -} - -static int virtio_crypto_rsa_verify(struct akcipher_request *req) -{ - return virtio_crypto_rsa_req(req, VIRTIO_CRYPTO_AKCIPHER_VERIFY); -} - static int virtio_crypto_rsa_set_key(struct crypto_akcipher *tfm, const void *key, unsigned int keylen, @@ -524,16 +498,19 @@ static struct virtio_crypto_akcipher_algo virtio_crypto_akcipher_algs[] = { .algo.base = { .encrypt = virtio_crypto_rsa_encrypt, .decrypt = virtio_crypto_rsa_decrypt, - .sign = virtio_crypto_rsa_sign, - .verify = virtio_crypto_rsa_verify, + /* + * Must specify an arbitrary hash algorithm upon + * set_{pub,priv}_key (even though it's not used + * by encrypt/decrypt) because qemu checks for it. + */ .set_pub_key = virtio_crypto_p1pad_rsa_sha1_set_pub_key, .set_priv_key = virtio_crypto_p1pad_rsa_sha1_set_priv_key, .max_size = virtio_crypto_rsa_max_size, .init = virtio_crypto_rsa_init_tfm, .exit = virtio_crypto_rsa_exit_tfm, .base = { - .cra_name = "pkcs1pad(rsa,sha1)", - .cra_driver_name = "virtio-pkcs1-rsa-with-sha1", + .cra_name = "pkcs1pad(rsa)", + .cra_driver_name = "virtio-pkcs1-rsa", .cra_priority = 150, .cra_module = THIS_MODULE, .cra_ctxsize = sizeof(struct virtio_crypto_akcipher_ctx), diff --git a/include/uapi/linux/virtio_crypto.h b/include/uapi/linux/virtio_crypto.h index 71a54a6849ca..2fccb64c9d6b 100644 --- a/include/uapi/linux/virtio_crypto.h +++ b/include/uapi/linux/virtio_crypto.h @@ -329,6 +329,7 @@ struct virtio_crypto_op_header { VIRTIO_CRYPTO_OPCODE(VIRTIO_CRYPTO_SERVICE_AKCIPHER, 0x00) #define VIRTIO_CRYPTO_AKCIPHER_DECRYPT \ VIRTIO_CRYPTO_OPCODE(VIRTIO_CRYPTO_SERVICE_AKCIPHER, 0x01) + /* akcipher sign/verify opcodes are deprecated */ #define VIRTIO_CRYPTO_AKCIPHER_SIGN \ VIRTIO_CRYPTO_OPCODE(VIRTIO_CRYPTO_SERVICE_AKCIPHER, 0x02) #define VIRTIO_CRYPTO_AKCIPHER_VERIFY \ -- cgit v1.2.3