This patch has *not* been tested as I don't have the hardware. It's purpose is to show how to use the kpp API. Based on https://patchwork.kernel.org/patch/9022371/ Signed-off-by: Salvatore Benedetto <salvatore.benedetto@xxxxxxxxx> --- v2: Also convert ecc_make_key to kpp API net/bluetooth/smp.c | 184 +++++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 181 insertions(+), 3 deletions(-) diff --git a/net/bluetooth/smp.c b/net/bluetooth/smp.c index 50976a6..4d28704 100644 --- a/net/bluetooth/smp.c +++ b/net/bluetooth/smp.c @@ -25,6 +25,8 @@ #include <crypto/b128ops.h> #include <crypto/hash.h> #include <crypto/skcipher.h> +#include <crypto/kpp.h> +#include <crypto/ecdh.h> #include <net/bluetooth/bluetooth.h> #include <net/bluetooth/hci_core.h> @@ -211,6 +213,182 @@ static int aes_cmac(struct crypto_shash *tfm, const u8 k[16], const u8 *m, return 0; } +struct ecdh_completion { + struct completion completion; + int err; +}; + +static void ecdh_complete(struct crypto_async_request *req, int err) +{ + struct ecdh_completion *res = req->data; + + if (err == -EINPROGRESS) + return; + + res->err = err; + complete(&res->completion); +} + +static inline void swap_digits(u64 *in, u64 *out, unsigned int ndigits) +{ + int i; + + for (i = 0; i < ndigits; i++) + out[i] = __swab64(in[ndigits - 1 - i]); +} + +static bool compute_ecdh_shared_secret(const u8 public_key[64], + const u8 private_key[32], u8 secret[32]) +{ + struct crypto_kpp *tfm; + struct kpp_request *req; + struct ecdh_params p; + struct ecdh_completion result; + struct scatterlist src, dst; + u8 tmp[64]; + int err = -ENOMEM; + + tfm = crypto_alloc_kpp("ecdh", CRYPTO_ALG_INTERNAL, 0); + if (IS_ERR(tfm)) { + pr_err("alg: kpp: Failed to load tfm for kpp: %ld\n", + PTR_ERR(tfm)); + return false; + } + + req = kpp_request_alloc(tfm, GFP_KERNEL); + if (!req) + goto free_kpp; + + init_completion(&result.completion); + + /* Set curve_id */ + p.curve_id = ECC_CURVE_NIST_P256; + err = crypto_kpp_set_params(tfm, (void *)&p, sizeof(p)); + if (err) + goto free_req; + + /* Security Manager Protocol holds digits in litte-endian order + * while ECC API expect big-endian data + */ + swap_digits((u64 *)private_key, (u64 *)tmp, 4); + + /* Set A private Key */ + err = crypto_kpp_set_secret(tfm, (void *)tmp, 32); + if (err) + goto free_all; + + swap_digits((u64 *)public_key, (u64 *)tmp, 4); /* x */ + swap_digits((u64 *)&public_key[32], (u64 *)&tmp[32], 4); /* y */ + + sg_init_one(&src, tmp, 64); + sg_init_one(&dst, secret, 32); + kpp_request_set_input(req, &src, 64); + kpp_request_set_output(req, &dst, 32); + kpp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG, + ecdh_complete, &result); + err = crypto_kpp_compute_shared_secret(req); + if (err == -EINPROGRESS) { + wait_for_completion(&result.completion); + err = result.err; + } + if (err < 0) { + pr_err("alg: ecdh: compute shard secret test failed. err %d\n", + err); + goto free_all; + } + + swap_digits((u64 *)secret, (u64 *)tmp, 4); + memcpy(secret, tmp, 32); + +free_all: +free_req: + kpp_request_free(req); +free_kpp: + crypto_free_kpp(tfm); + return (err == 0); +} + +bool generate_ecdh_key_pair(u8 public_key[64], u8 private_key[32]) +{ + struct crypto_kpp *tfm; + struct kpp_request *req; + struct ecdh_params p; + struct ecdh_completion result; + struct scatterlist dst; + u8 tmp[64]; + int err = -ENOMEM; + const unsigned short max_tries = 16; + unsigned short tries = 0; + + tfm = crypto_alloc_kpp("ecdh", CRYPTO_ALG_INTERNAL, 0); + if (IS_ERR(tfm)) { + pr_err("alg: kpp: Failed to load tfm for kpp: %ld\n", + PTR_ERR(tfm)); + return false; + } + + req = kpp_request_alloc(tfm, GFP_KERNEL); + if (!req) + goto free_kpp; + + init_completion(&result.completion); + + /* Set curve_id */ + p.curve_id = ECC_CURVE_NIST_P256; + err = crypto_kpp_set_params(tfm, (void *)&p, sizeof(p)); + if (err) + goto free_req; + + do { + if (tries++ >= max_tries) + goto free_all; + + get_random_bytes(private_key, 32); + + /* Set private Key */ + err = crypto_kpp_set_secret(tfm, (void *)private_key, 32); + if (err) + goto free_all; + + sg_init_one(&dst, tmp, 64); + kpp_request_set_output(req, &dst, 64); + kpp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG, + ecdh_complete, &result); + + err = crypto_kpp_generate_public_key(req); + + if (err == -EINPROGRESS) { + wait_for_completion(&result.completion); + err = result.err; + } + + /* Private key is not valid. Regenerate */ + if (err == -EINVAL) + continue; + + if (err < 0) + goto free_all; + else + break; + + } while (true); + + /* Keys are handed back in little endian as expected by Security + * Manager Protocol + */ + swap_digits((u64 *)tmp, (u64 *)public_key, 4); /* x */ + swap_digits((u64 *)&tmp[32], (u64 *)&public_key[32], 4); /* y */ + swap_digits((u64 *)private_key, (u64 *)tmp, 4); + memcpy(private_key, tmp, 32); + +free_all: +free_req: + kpp_request_free(req); +free_kpp: + crypto_free_kpp(tfm); + return (err == 0); +} + static int smp_f4(struct crypto_shash *tfm_cmac, const u8 u[32], const u8 v[32], const u8 x[16], u8 z, u8 res[16]) { @@ -564,7 +742,7 @@ int smp_generate_oob(struct hci_dev *hdev, u8 hash[16], u8 rand[16]) } else { while (true) { /* Generate local key pair for Secure Connections */ - if (!ecc_make_key(smp->local_pk, smp->local_sk)) + if (!generate_ecdh_key_pair(smp->local_pk, smp->local_sk)) return -EIO; /* This is unlikely, but we need to check that @@ -1862,7 +2040,7 @@ static u8 sc_send_public_key(struct smp_chan *smp) } else { while (true) { /* Generate local key pair for Secure Connections */ - if (!ecc_make_key(smp->local_pk, smp->local_sk)) + if (!generate_ecdh_key_pair(smp->local_pk, smp->local_sk)) return SMP_UNSPECIFIED; /* This is unlikely, but we need to check that @@ -2630,7 +2808,7 @@ static int smp_cmd_public_key(struct l2cap_conn *conn, struct sk_buff *skb) SMP_DBG("Remote Public Key X: %32phN", smp->remote_pk); SMP_DBG("Remote Public Key Y: %32phN", smp->remote_pk + 32); - if (!ecdh_shared_secret(smp->remote_pk, smp->local_sk, smp->dhkey)) + if (!compute_ecdh_shared_secret(smp->remote_pk, smp->local_sk, smp->dhkey)) return SMP_UNSPECIFIED; SMP_DBG("DHKey %32phN", smp->dhkey); -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
