| /* Crypto operations using stored keys |
| * |
| * Copyright (c) 2016, Intel Corporation |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU General Public License |
| * as published by the Free Software Foundation; either version |
| * 2 of the License, or (at your option) any later version. |
| */ |
| |
| #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" |
| |
| static ssize_t dh_data_from_key(key_serial_t keyid, void **data) |
| { |
| struct key *key; |
| key_ref_t key_ref; |
| long status; |
| ssize_t ret; |
| |
| key_ref = lookup_user_key(keyid, 0, KEY_NEED_READ); |
| if (IS_ERR(key_ref)) { |
| ret = -ENOKEY; |
| goto error; |
| } |
| |
| key = key_ref_to_ptr(key_ref); |
| |
| ret = -EOPNOTSUPP; |
| if (key->type == &key_type_user) { |
| down_read(&key->sem); |
| status = key_validate(key); |
| if (status == 0) { |
| const struct user_key_payload *payload; |
| uint8_t *duplicate; |
| |
| payload = user_key_payload_locked(key); |
| |
| duplicate = kmemdup(payload->data, payload->datalen, |
| GFP_KERNEL); |
| if (duplicate) { |
| *data = duplicate; |
| ret = payload->datalen; |
| } else { |
| ret = -ENOMEM; |
| } |
| } |
| up_read(&key->sem); |
| } |
| |
| key_put(key); |
| 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[]; |
| }; |
| |
| static int kdf_alloc(struct kdf_sdesc **sdesc_ret, char *hashname) |
| { |
| struct crypto_shash *tfm; |
| struct kdf_sdesc *sdesc; |
| int size; |
| int err; |
| |
| /* allocate synchronous hash */ |
| tfm = crypto_alloc_shash(hashname, 0, 0); |
| if (IS_ERR(tfm)) { |
| pr_info("could not allocate digest TFM handle %s\n", hashname); |
| return PTR_ERR(tfm); |
| } |
| |
| err = -EINVAL; |
| if (crypto_shash_digestsize(tfm) == 0) |
| goto out_free_tfm; |
| |
| err = -ENOMEM; |
| size = sizeof(struct shash_desc) + crypto_shash_descsize(tfm); |
| sdesc = kmalloc(size, GFP_KERNEL); |
| if (!sdesc) |
| goto out_free_tfm; |
| sdesc->shash.tfm = tfm; |
| |
| *sdesc_ret = sdesc; |
| |
| return 0; |
| |
| out_free_tfm: |
| crypto_free_shash(tfm); |
| return err; |
| } |
| |
| static void kdf_dealloc(struct kdf_sdesc *sdesc) |
| { |
| if (!sdesc) |
| return; |
| |
| if (sdesc->shash.tfm) |
| crypto_free_shash(sdesc->shash.tfm); |
| |
| kzfree(sdesc); |
| } |
| |
| /* |
| * Implementation of the KDF in counter mode according to SP800-108 section 5.1 |
| * as well as SP800-56A section 5.8.1 (Single-step KDF). |
| * |
| * SP800-56A: |
| * The src pointer is defined as Z || other info where Z is the shared secret |
| * from DH and other info is an arbitrary string (see SP800-56A section |
| * 5.8.1.2). |
| * |
| * 'dlen' must be a multiple of the digest size. |
| */ |
| static int kdf_ctr(struct kdf_sdesc *sdesc, const u8 *src, unsigned int slen, |
| u8 *dst, unsigned int dlen, unsigned int zlen) |
| { |
| struct shash_desc *desc = &sdesc->shash; |
| unsigned int h = crypto_shash_digestsize(desc->tfm); |
| int err = 0; |
| u8 *dst_orig = dst; |
| __be32 counter = cpu_to_be32(1); |
| |
| while (dlen) { |
| err = crypto_shash_init(desc); |
| if (err) |
| goto err; |
| |
| err = crypto_shash_update(desc, (u8 *)&counter, sizeof(__be32)); |
| if (err) |
| goto err; |
| |
| if (zlen && h) { |
| u8 tmpbuffer[32]; |
| size_t chunk = min_t(size_t, zlen, sizeof(tmpbuffer)); |
| memset(tmpbuffer, 0, chunk); |
| |
| do { |
| err = crypto_shash_update(desc, tmpbuffer, |
| chunk); |
| if (err) |
| goto err; |
| |
| zlen -= chunk; |
| chunk = min_t(size_t, zlen, sizeof(tmpbuffer)); |
| } while (zlen); |
| } |
| |
| if (src && slen) { |
| err = crypto_shash_update(desc, src, slen); |
| if (err) |
| goto err; |
| } |
| |
| err = crypto_shash_final(desc, dst); |
| if (err) |
| goto err; |
| |
| dlen -= h; |
| dst += h; |
| counter = cpu_to_be32(be32_to_cpu(counter) + 1); |
| } |
| |
| return 0; |
| |
| err: |
| memzero_explicit(dst_orig, dlen); |
| return err; |
| } |
| |
| static int keyctl_dh_compute_kdf(struct kdf_sdesc *sdesc, |
| char __user *buffer, size_t buflen, |
| uint8_t *kbuf, size_t kbuflen, size_t lzero) |
| { |
| uint8_t *outbuf = NULL; |
| int ret; |
| size_t outbuf_len = roundup(buflen, |
| crypto_shash_digestsize(sdesc->shash.tfm)); |
| |
| outbuf = kmalloc(outbuf_len, GFP_KERNEL); |
| if (!outbuf) { |
| ret = -ENOMEM; |
| goto err; |
| } |
| |
| ret = kdf_ctr(sdesc, kbuf, kbuflen, outbuf, outbuf_len, lzero); |
| if (ret) |
| goto err; |
| |
| ret = buflen; |
| if (copy_to_user(buffer, outbuf, buflen) != 0) |
| ret = -EFAULT; |
| |
| err: |
| kzfree(outbuf); |
| return ret; |
| } |
| |
| long __keyctl_dh_compute(struct keyctl_dh_params __user *params, |
| char __user *buffer, size_t buflen, |
| struct keyctl_kdf_params *kdfcopy) |
| { |
| long ret; |
| ssize_t dlen; |
| int secretlen; |
| int outlen; |
| struct keyctl_dh_params pcopy; |
| 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 out1; |
| } |
| if (copy_from_user(&pcopy, params, sizeof(pcopy)) != 0) { |
| ret = -EFAULT; |
| goto out1; |
| } |
| |
| if (kdfcopy) { |
| char *hashname; |
| |
| if (memchr_inv(kdfcopy->__spare, 0, sizeof(kdfcopy->__spare))) { |
| ret = -EINVAL; |
| goto out1; |
| } |
| |
| if (buflen > KEYCTL_KDF_MAX_OUTPUT_LEN || |
| kdfcopy->otherinfolen > KEYCTL_KDF_MAX_OI_LEN) { |
| ret = -EMSGSIZE; |
| goto out1; |
| } |
| |
| /* get KDF name string */ |
| hashname = strndup_user(kdfcopy->hashname, CRYPTO_MAX_ALG_NAME); |
| if (IS_ERR(hashname)) { |
| ret = PTR_ERR(hashname); |
| goto out1; |
| } |
| |
| /* allocate KDF from the kernel crypto API */ |
| ret = kdf_alloc(&sdesc, hashname); |
| kfree(hashname); |
| if (ret) |
| goto out1; |
| } |
| |
| 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; |
| |
| dlen = dh_data_from_key(pcopy.base, &dh_inputs.g); |
| if (dlen < 0) { |
| ret = dlen; |
| goto out2; |
| } |
| dh_inputs.g_size = dlen; |
| |
| dlen = dh_data_from_key(pcopy.private, &dh_inputs.key); |
| if (dlen < 0) { |
| ret = dlen; |
| goto out2; |
| } |
| dh_inputs.key_size = dlen; |
| |
| 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", 0, 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; |
| } |
| } |
| |
| outbuf = kzalloc(kdfcopy ? (outlen + kdfcopy->otherinfolen) : outlen, |
| GFP_KERNEL); |
| if (!outbuf) { |
| ret = -ENOMEM; |
| goto out4; |
| } |
| |
| sg_init_one(&outsg, outbuf, outlen); |
| |
| req = kpp_request_alloc(tfm, GFP_KERNEL); |
| if (!req) { |
| ret = -ENOMEM; |
| 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); |
| |
| /* |
| * For DH, generate_public_key and generate_shared_secret are |
| * the same calculation |
| */ |
| ret = crypto_kpp_generate_public_key(req); |
| if (ret == -EINPROGRESS) { |
| wait_for_completion(&compl.completion); |
| ret = compl.err; |
| if (ret) |
| goto out6; |
| } |
| |
| if (kdfcopy) { |
| /* |
| * 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; |
| } |
| |
| 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; |
| } |
| |
| long keyctl_dh_compute(struct keyctl_dh_params __user *params, |
| char __user *buffer, size_t buflen, |
| struct keyctl_kdf_params __user *kdf) |
| { |
| struct keyctl_kdf_params kdfcopy; |
| |
| if (!kdf) |
| return __keyctl_dh_compute(params, buffer, buflen, NULL); |
| |
| if (copy_from_user(&kdfcopy, kdf, sizeof(kdfcopy)) != 0) |
| return -EFAULT; |
| |
| return __keyctl_dh_compute(params, buffer, buflen, &kdfcopy); |
| } |