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Message-ID: <160518594688.2277919.5319312384536950170.stgit@warthog.procyon.org.uk>
Date: Thu, 12 Nov 2020 12:59:06 +0000
From: David Howells <dhowells@...hat.com>
To: herbert@...dor.apana.org.au, bfields@...ldses.org
Cc: dhowells@...hat.com, trond.myklebust@...merspace.com,
linux-crypto@...r.kernel.org, linux-afs@...ts.infradead.org,
linux-cifs@...r.kernel.org, linux-nfs@...r.kernel.org,
linux-fsdevel@...r.kernel.org, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH 10/18] crypto/krb5: Implement the AES encrypt/decrypt from
rfc8009
Implement encryption and decryption functions for AES + HMAC-SHA2 as
described in rfc8009 sec 5.
Signed-off-by: David Howells <dhowells@...hat.com>
---
crypto/krb5/rfc8009_aes2.c | 205 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 203 insertions(+), 2 deletions(-)
diff --git a/crypto/krb5/rfc8009_aes2.c b/crypto/krb5/rfc8009_aes2.c
index 9f0f0f410d91..df517435be73 100644
--- a/crypto/krb5/rfc8009_aes2.c
+++ b/crypto/krb5/rfc8009_aes2.c
@@ -10,6 +10,7 @@
#include <crypto/skcipher.h>
#include <crypto/hash.h>
#include <linux/slab.h>
+#include <linux/random.h>
#include "internal.h"
static const struct krb5_buffer rfc8009_no_context = { .len = 0, .data = "" };
@@ -183,13 +184,213 @@ static int rfc8009_random_to_key(const struct krb5_enctype *krb5,
return 0;
}
+/*
+ * Apply encryption and checksumming functions to part of an skbuff.
+ */
+static ssize_t rfc8009_encrypt(const struct krb5_enctype *krb5,
+ struct krb5_enc_keys *keys,
+ struct scatterlist *sg, unsigned nr_sg, size_t sg_len,
+ size_t data_offset, size_t data_len,
+ bool preconfounded)
+{
+ struct skcipher_request *req;
+ struct shash_desc *desc;
+ ssize_t ret, done;
+ size_t bsize, base_len, secure_offset, secure_len, pad_len, cksum_offset;
+ void *buffer;
+ u8 *cksum, *iv;
+
+ if (WARN_ON(data_offset != krb5->conf_len))
+ return -EINVAL; /* Can't set offset on skcipher */
+
+ base_len = krb5->conf_len + data_len;
+ secure_len = base_len;
+ pad_len = secure_len - base_len;
+ secure_offset = 0;
+ cksum_offset = secure_offset + secure_len;
+
+ bsize = krb5_shash_size(keys->Ki) +
+ krb5_digest_size(keys->Ki) +
+ krb5_sync_skcipher_size(keys->Ke) +
+ krb5_sync_skcipher_ivsize(keys->Ke);
+ bsize = max_t(size_t, bsize, krb5->conf_len);
+ bsize = max_t(size_t, bsize, krb5->block_len);
+ buffer = kzalloc(bsize, GFP_NOFS);
+ if (!buffer)
+ return -ENOMEM;
+
+ /* Insert the confounder into the skb */
+ ret = -EFAULT;
+ if (!preconfounded) {
+ get_random_bytes(buffer, krb5->conf_len);
+ done = sg_pcopy_to_buffer(sg, nr_sg, buffer, krb5->conf_len,
+ secure_offset);
+ if (done != krb5->conf_len)
+ goto error;
+ }
+
+ /* We need to pad out to the crypto blocksize. */
+ if (pad_len) {
+ done = sg_zero_buffer(sg, nr_sg, pad_len, data_offset + data_len);
+ if (done != pad_len)
+ goto error;
+ }
+
+ /* Encrypt the secure region with key Ke. */
+ req = buffer +
+ krb5_shash_size(keys->Ki) +
+ krb5_digest_size(keys->Ki);
+ iv = buffer +
+ krb5_shash_size(keys->Ki) +
+ krb5_digest_size(keys->Ki) +
+ krb5_sync_skcipher_size(keys->Ke);
+
+ skcipher_request_set_sync_tfm(req, keys->Ke);
+ skcipher_request_set_callback(req, 0, NULL, NULL);
+ skcipher_request_set_crypt(req, sg, sg, secure_len, iv);
+ ret = crypto_skcipher_encrypt(req);
+ if (ret < 0)
+ goto error;
+
+ /* Calculate the checksum using key Ki */
+ cksum = buffer + krb5_shash_size(keys->Ki);
+
+ desc = buffer;
+ desc->tfm = keys->Ki;
+ ret = crypto_shash_init(desc);
+ if (ret < 0)
+ goto error;
+
+ memset(iv, 0, crypto_sync_skcipher_ivsize(keys->Ke));
+ ret = crypto_shash_update(desc, iv, crypto_sync_skcipher_ivsize(keys->Ke));
+ if (ret < 0)
+ goto error;
+
+ ret = crypto_shash_update_sg(desc, sg, secure_offset, secure_len);
+ if (ret < 0)
+ goto error;
+
+ ret = crypto_shash_final(desc, cksum);
+ if (ret < 0)
+ goto error;
+
+ /* Append the checksum into the buffer. */
+ ret = -EFAULT;
+ sg_zero_buffer(sg, nr_sg, 3, cksum_offset);
+ done = sg_pcopy_from_buffer(sg, nr_sg, cksum, krb5->cksum_len, cksum_offset);
+ if (done != krb5->cksum_len)
+ goto error;
+
+ ret = secure_len + krb5->cksum_len;
+
+error:
+ kfree_sensitive(buffer);
+ return ret;
+}
+
+/*
+ * Apply decryption and checksumming functions to part of an skbuff. The
+ * offset and length are updated to reflect the actual content of the encrypted
+ * region.
+ */
+static int rfc8009_decrypt(const struct krb5_enctype *krb5,
+ struct krb5_enc_keys *keys,
+ struct scatterlist *sg, unsigned nr_sg,
+ size_t *_offset, size_t *_len,
+ int *_error_code)
+{
+ struct skcipher_request *req;
+ struct shash_desc *desc;
+ ssize_t done;
+ size_t bsize, secure_len, offset = *_offset, len = *_len;
+ void *buffer = NULL;
+ int ret;
+ u8 *cksum, *cksum2, *iv;
+
+ if (WARN_ON(*_offset != 0))
+ return -EINVAL; /* Can't set offset on skcipher */
+
+ if (len < krb5->conf_len + krb5->cksum_len) {
+ *_error_code = 1; //RXGK_SEALED_INCON;
+ return -EPROTO;
+ }
+ secure_len = len - krb5->cksum_len;
+
+ bsize = krb5_shash_size(keys->Ki) +
+ krb5_digest_size(keys->Ki) * 2 +
+ krb5_sync_skcipher_size(keys->Ke) +
+ krb5_sync_skcipher_ivsize(keys->Ke);
+ buffer = kzalloc(bsize, GFP_NOFS);
+ if (!buffer)
+ return -ENOMEM;
+
+ cksum = buffer +
+ krb5_shash_size(keys->Ki);
+ cksum2 = buffer +
+ krb5_shash_size(keys->Ki) +
+ krb5_digest_size(keys->Ki);
+ req = buffer +
+ krb5_shash_size(keys->Ki) +
+ krb5_digest_size(keys->Ki) * 2;
+ iv = buffer +
+ krb5_shash_size(keys->Ki) +
+ krb5_digest_size(keys->Ki) * 2 +
+ krb5_sync_skcipher_size(keys->Ke);
+
+ /* Calculate the checksum using key Ki */
+ desc = buffer;
+ desc->tfm = keys->Ki;
+ ret = crypto_shash_init(desc);
+ if (ret < 0)
+ goto error;
+
+ ret = crypto_shash_update(desc, iv, crypto_sync_skcipher_ivsize(keys->Ke));
+ if (ret < 0)
+ goto error;
+
+ ret = crypto_shash_update_sg(desc, sg, 0, secure_len);
+ if (ret < 0)
+ goto error;
+
+ ret = crypto_shash_final(desc, cksum);
+ if (ret < 0)
+ goto error;
+
+ /* Get the checksum from the buffer. */
+ ret = -EFAULT;
+ done = sg_pcopy_to_buffer(sg, nr_sg, cksum2, krb5->cksum_len,
+ offset + len - krb5->cksum_len);
+ if (done != krb5->cksum_len)
+ goto error;
+
+ if (memcmp(cksum, cksum2, krb5->cksum_len) != 0) {
+ *_error_code = 1; //RXGK_SEALED_INCON;
+ ret = -EPROTO;
+ goto error;
+ }
+
+ /* Decrypt the secure region with key Ke. */
+ skcipher_request_set_sync_tfm(req, keys->Ke);
+ skcipher_request_set_callback(req, 0, NULL, NULL);
+ skcipher_request_set_crypt(req, sg, sg, secure_len, iv);
+ ret = crypto_skcipher_decrypt(req);
+
+ *_offset += krb5->conf_len;
+ *_len -= krb5->conf_len + krb5->cksum_len;
+ ret = 0;
+
+error:
+ kfree_sensitive(buffer);
+ return ret;
+}
+
static const struct krb5_crypto_profile rfc8009_crypto_profile = {
.calc_PRF = rfc8009_calc_PRF,
.calc_Kc = rfc8009_calc_Ki,
.calc_Ke = rfc8009_calc_Ke,
.calc_Ki = rfc8009_calc_Ki,
- .encrypt = NULL, //rfc8009_encrypt,
- .decrypt = NULL, //rfc8009_decrypt,
+ .encrypt = rfc8009_encrypt,
+ .decrypt = rfc8009_decrypt,
.get_mic = rfc3961_get_mic,
.verify_mic = rfc3961_verify_mic,
};
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