diff options
-rw-r--r-- | security/keys/Kconfig | 2 | ||||
-rw-r--r-- | security/keys/dh.c | 272 |
2 files changed, 171 insertions, 103 deletions
diff --git a/security/keys/Kconfig b/security/keys/Kconfig index 00b7431..a7a23b5 100644 --- a/security/keys/Kconfig +++ b/security/keys/Kconfig @@ -93,9 +93,9 @@ config ENCRYPTED_KEYS config KEY_DH_OPERATIONS bool "Diffie-Hellman operations on retained keys" depends on KEYS - select MPILIB select CRYPTO select CRYPTO_HASH + select CRYPTO_DH help This option provides support for calculating Diffie-Hellman public keys and shared secrets using values stored as keys diff --git a/security/keys/dh.c b/security/keys/dh.c index 63ac87d..4755d4b 100644 --- a/security/keys/dh.c +++ b/security/keys/dh.c @@ -8,34 +8,17 @@ * 2 of the License, or (at your option) any later version. */ -#include <linux/mpi.h> #include <linux/slab.h> #include <linux/uaccess.h> +#include <linux/scatterlist.h> #include <linux/crypto.h> #include <crypto/hash.h> +#include <crypto/kpp.h> +#include <crypto/dh.h> #include <keys/user-type.h> #include "internal.h" -/* - * Public key or shared secret generation function [RFC2631 sec 2.1.1] - * - * ya = g^xa mod p; - * or - * ZZ = yb^xa mod p; - * - * where xa is the local private key, ya is the local public key, g is - * the generator, p is the prime, yb is the remote public key, and ZZ - * is the shared secret. - * - * Both are the same calculation, so g or yb are the "base" and ya or - * ZZ are the "result". - */ -static int do_dh(MPI result, MPI base, MPI xa, MPI p) -{ - return mpi_powm(result, base, xa, p); -} - -static ssize_t mpi_from_key(key_serial_t keyid, size_t maxlen, MPI *mpi) +static ssize_t dh_data_from_key(key_serial_t keyid, void **data) { struct key *key; key_ref_t key_ref; @@ -56,19 +39,17 @@ static ssize_t mpi_from_key(key_serial_t keyid, size_t maxlen, MPI *mpi) status = key_validate(key); if (status == 0) { const struct user_key_payload *payload; + uint8_t *duplicate; payload = user_key_payload_locked(key); - if (maxlen == 0) { - *mpi = NULL; + duplicate = kmemdup(payload->data, payload->datalen, + GFP_KERNEL); + if (duplicate) { + *data = duplicate; ret = payload->datalen; - } else if (payload->datalen <= maxlen) { - *mpi = mpi_read_raw_data(payload->data, - payload->datalen); - if (*mpi) - ret = payload->datalen; } else { - ret = -EINVAL; + ret = -ENOMEM; } } up_read(&key->sem); @@ -79,6 +60,29 @@ error: return ret; } +static void dh_free_data(struct dh *dh) +{ + kzfree(dh->key); + kzfree(dh->p); + kzfree(dh->g); +} + +struct dh_completion { + struct completion completion; + int err; +}; + +static void dh_crypto_done(struct crypto_async_request *req, int err) +{ + struct dh_completion *compl = req->data; + + if (err == -EINPROGRESS) + return; + + compl->err = err; + complete(&compl->completion); +} + struct kdf_sdesc { struct shash_desc shash; char ctx[]; @@ -140,7 +144,7 @@ static void kdf_dealloc(struct kdf_sdesc *sdesc) * 5.8.1.2). */ static int kdf_ctr(struct kdf_sdesc *sdesc, const u8 *src, unsigned int slen, - u8 *dst, unsigned int dlen) + u8 *dst, unsigned int dlen, unsigned int zlen) { struct shash_desc *desc = &sdesc->shash; unsigned int h = crypto_shash_digestsize(desc->tfm); @@ -157,6 +161,22 @@ static int kdf_ctr(struct kdf_sdesc *sdesc, const u8 *src, unsigned int slen, if (err) goto err; + if (zlen && h) { + u8 tmpbuffer[h]; + size_t chunk = min_t(size_t, zlen, h); + memset(tmpbuffer, 0, chunk); + + do { + err = crypto_shash_update(desc, tmpbuffer, + chunk); + if (err) + goto err; + + zlen -= chunk; + chunk = min_t(size_t, zlen, h); + } while (zlen); + } + if (src && slen) { err = crypto_shash_update(desc, src, slen); if (err) @@ -192,7 +212,7 @@ err: static int keyctl_dh_compute_kdf(struct kdf_sdesc *sdesc, char __user *buffer, size_t buflen, - uint8_t *kbuf, size_t kbuflen) + uint8_t *kbuf, size_t kbuflen, size_t lzero) { uint8_t *outbuf = NULL; int ret; @@ -203,7 +223,7 @@ static int keyctl_dh_compute_kdf(struct kdf_sdesc *sdesc, goto err; } - ret = kdf_ctr(sdesc, kbuf, kbuflen, outbuf, buflen); + ret = kdf_ctr(sdesc, kbuf, kbuflen, outbuf, buflen, lzero); if (ret) goto err; @@ -221,21 +241,26 @@ long __keyctl_dh_compute(struct keyctl_dh_params __user *params, struct keyctl_kdf_params *kdfcopy) { long ret; - MPI base, private, prime, result; - unsigned nbytes; + ssize_t dlen; + int secretlen; + int outlen; struct keyctl_dh_params pcopy; - uint8_t *kbuf; - ssize_t keylen; - size_t resultlen; + struct dh dh_inputs; + struct scatterlist outsg; + struct dh_completion compl; + struct crypto_kpp *tfm; + struct kpp_request *req; + uint8_t *secret; + uint8_t *outbuf; struct kdf_sdesc *sdesc = NULL; if (!params || (!buffer && buflen)) { ret = -EINVAL; - goto out; + goto out1; } if (copy_from_user(&pcopy, params, sizeof(pcopy)) != 0) { ret = -EFAULT; - goto out; + goto out1; } if (kdfcopy) { @@ -244,104 +269,147 @@ long __keyctl_dh_compute(struct keyctl_dh_params __user *params, if (buflen > KEYCTL_KDF_MAX_OUTPUT_LEN || kdfcopy->otherinfolen > KEYCTL_KDF_MAX_OI_LEN) { ret = -EMSGSIZE; - goto out; + goto out1; } /* get KDF name string */ hashname = strndup_user(kdfcopy->hashname, CRYPTO_MAX_ALG_NAME); if (IS_ERR(hashname)) { ret = PTR_ERR(hashname); - goto out; + goto out1; } /* allocate KDF from the kernel crypto API */ ret = kdf_alloc(&sdesc, hashname); kfree(hashname); if (ret) - goto out; + goto out1; } - /* - * If the caller requests postprocessing with a KDF, allow an - * arbitrary output buffer size since the KDF ensures proper truncation. - */ - keylen = mpi_from_key(pcopy.prime, kdfcopy ? SIZE_MAX : buflen, &prime); - if (keylen < 0 || !prime) { - /* buflen == 0 may be used to query the required buffer size, - * which is the prime key length. - */ - ret = keylen; - goto out; + memset(&dh_inputs, 0, sizeof(dh_inputs)); + + dlen = dh_data_from_key(pcopy.prime, &dh_inputs.p); + if (dlen < 0) { + ret = dlen; + goto out1; } + dh_inputs.p_size = dlen; - /* The result is never longer than the prime */ - resultlen = keylen; + dlen = dh_data_from_key(pcopy.base, &dh_inputs.g); + if (dlen < 0) { + ret = dlen; + goto out2; + } + dh_inputs.g_size = dlen; - keylen = mpi_from_key(pcopy.base, SIZE_MAX, &base); - if (keylen < 0 || !base) { - ret = keylen; - goto error1; + dlen = dh_data_from_key(pcopy.private, &dh_inputs.key); + if (dlen < 0) { + ret = dlen; + goto out2; } + dh_inputs.key_size = dlen; - keylen = mpi_from_key(pcopy.private, SIZE_MAX, &private); - if (keylen < 0 || !private) { - ret = keylen; - goto error2; + secretlen = crypto_dh_key_len(&dh_inputs); + secret = kmalloc(secretlen, GFP_KERNEL); + if (!secret) { + ret = -ENOMEM; + goto out2; + } + ret = crypto_dh_encode_key(secret, secretlen, &dh_inputs); + if (ret) + goto out3; + + tfm = crypto_alloc_kpp("dh", CRYPTO_ALG_TYPE_KPP, 0); + if (IS_ERR(tfm)) { + ret = PTR_ERR(tfm); + goto out3; + } + + ret = crypto_kpp_set_secret(tfm, secret, secretlen); + if (ret) + goto out4; + + outlen = crypto_kpp_maxsize(tfm); + + if (!kdfcopy) { + /* + * When not using a KDF, buflen 0 is used to read the + * required buffer length + */ + if (buflen == 0) { + ret = outlen; + goto out4; + } else if (outlen > buflen) { + ret = -EOVERFLOW; + goto out4; + } } - result = mpi_alloc(0); - if (!result) { + outbuf = kzalloc(kdfcopy ? (outlen + kdfcopy->otherinfolen) : outlen, + GFP_KERNEL); + if (!outbuf) { ret = -ENOMEM; - goto error3; + goto out4; } - /* allocate space for DH shared secret and SP800-56A otherinfo */ - kbuf = kmalloc(kdfcopy ? (resultlen + kdfcopy->otherinfolen) : resultlen, - GFP_KERNEL); - if (!kbuf) { + sg_init_one(&outsg, outbuf, outlen); + + req = kpp_request_alloc(tfm, GFP_KERNEL); + if (!req) { ret = -ENOMEM; - goto error4; + goto out5; } + kpp_request_set_input(req, NULL, 0); + kpp_request_set_output(req, &outsg, outlen); + init_completion(&compl.completion); + kpp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG | + CRYPTO_TFM_REQ_MAY_SLEEP, + dh_crypto_done, &compl); + /* - * Concatenate SP800-56A otherinfo past DH shared secret -- the - * input to the KDF is (DH shared secret || otherinfo) + * For DH, generate_public_key and generate_shared_secret are + * the same calculation */ - if (kdfcopy && - copy_from_user(kbuf + resultlen, kdfcopy->otherinfo, - kdfcopy->otherinfolen) != 0) { - ret = -EFAULT; - goto error5; + ret = crypto_kpp_generate_public_key(req); + if (ret == -EINPROGRESS) { + wait_for_completion(&compl.completion); + ret = compl.err; + if (ret) + goto out6; } - ret = do_dh(result, base, private, prime); - if (ret) - goto error5; - - ret = mpi_read_buffer(result, kbuf, resultlen, &nbytes, NULL); - if (ret != 0) - goto error5; - if (kdfcopy) { - ret = keyctl_dh_compute_kdf(sdesc, buffer, buflen, kbuf, - resultlen + kdfcopy->otherinfolen); - } else { - ret = nbytes; - if (copy_to_user(buffer, kbuf, nbytes) != 0) + /* + * Concatenate SP800-56A otherinfo past DH shared secret -- the + * input to the KDF is (DH shared secret || otherinfo) + */ + if (copy_from_user(outbuf + req->dst_len, kdfcopy->otherinfo, + kdfcopy->otherinfolen) != 0) { ret = -EFAULT; + goto out6; + } + + ret = keyctl_dh_compute_kdf(sdesc, buffer, buflen, outbuf, + req->dst_len + kdfcopy->otherinfolen, + outlen - req->dst_len); + } else if (copy_to_user(buffer, outbuf, req->dst_len) == 0) { + ret = req->dst_len; + } else { + ret = -EFAULT; } -error5: - kzfree(kbuf); -error4: - mpi_free(result); -error3: - mpi_free(private); -error2: - mpi_free(base); -error1: - mpi_free(prime); -out: +out6: + kpp_request_free(req); +out5: + kzfree(outbuf); +out4: + crypto_free_kpp(tfm); +out3: + kzfree(secret); +out2: + dh_free_data(&dh_inputs); +out1: kdf_dealloc(sdesc); return ret; } |