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-rw-r--r--security/keys/dh.c423
1 files changed, 423 insertions, 0 deletions
diff --git a/security/keys/dh.c b/security/keys/dh.c
new file mode 100644
index 000000000..1abfa70ed
--- /dev/null
+++ b/security/keys/dh.c
@@ -0,0 +1,423 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Crypto operations using stored keys
+ *
+ * Copyright (c) 2016, Intel Corporation
+ */
+
+#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)
+{
+ kfree_sensitive(dh->key);
+ kfree_sensitive(dh->p);
+ kfree_sensitive(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);
+
+ kfree_sensitive(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:
+ kfree_sensitive(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:
+ kfree_sensitive(outbuf);
+out4:
+ crypto_free_kpp(tfm);
+out3:
+ kfree_sensitive(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);
+}
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