[PATCH net 08/24] crypto/krb5: Add an API to perform requests

David Howells
2025-02-03T14:24:48Z

Add an API by which users of the krb5 crypto library can perform crypto
requests, such as encrypt, decrypt, get_mic and verify_mic. These
functions take the previously prepared crypto objects to work on.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Herbert Xu <herbert@gondor.apana.org.au>
cc: "David S. Miller" <davem@davemloft.net>
cc: Chuck Lever <chuck.lever@oracle.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: Eric Dumazet <edumazet@google.com>
cc: Jakub Kicinski <kuba@kernel.org>
cc: Paolo Abeni <pabeni@redhat.com>
cc: Simon Horman <horms@kernel.org>
cc: linux-afs@lists.infradead.org
cc: linux-nfs@vger.kernel.org
cc: linux-crypto@vger.kernel.org
cc: netdev@vger.kernel.org
---
crypto/krb5/krb5_api.c | 141 +++++++++++++++++++++++++++++++++++++++++
include/crypto/krb5.h | 21 ++++++
2 files changed, 162 insertions(+)

diff --git a/crypto/krb5/krb5_api.c b/crypto/krb5/krb5_api.c
index f7f2528b3895..8fc3a1b9d4ad 100644
--- a/crypto/krb5/krb5_api.c
+++ b/crypto/krb5/krb5_api.c
@@ -292,3 +292,144 @@ struct crypto_shash *crypto_krb5_prepare_checksum(const struct krb5_enctype *krb
return ERR_PTR(ret);
}
EXPORT_SYMBOL(crypto_krb5_prepare_checksum);
+
+/**
+ * crypto_krb5_encrypt - Apply Kerberos encryption and integrity.
+ * @krb5: The encoding to use.
+ * @aead: The keyed crypto object to use.
+ * @sg: Scatterlist defining the crypto buffer.
+ * @nr_sg: The number of elements in @sg.
+ * @sg_len: The size of the buffer.
+ * @data_offset: The offset of the data in the @sg buffer.
+ * @data_len: The length of the data.
+ * @preconfounded: True if the confounder is already inserted.
+ *
+ * Using the specified Kerberos encoding, insert a confounder and padding as
+ * needed, encrypt this and the data in place and insert an integrity checksum
+ * into the buffer.
+ *
+ * The buffer must include space for the confounder, the checksum and any
+ * padding required. The caller can preinsert the confounder into the buffer
+ * (for testing, for example).
+ *
+ * The resulting secured blob may be less than the size of the buffer.
+ *
+ * Returns the size of the secure blob if successful, -ENOMEM on an allocation
+ * failure, -EFAULT if there is insufficient space, -EMSGSIZE if the confounder
+ * is too short or the data is misaligned. Other errors may also be returned
+ * from the crypto layer.
+ */
+ssize_t crypto_krb5_encrypt(const struct krb5_enctype *krb5,
+ struct crypto_aead *aead,
+ struct scatterlist *sg, unsigned int nr_sg,
+ size_t sg_len,
+ size_t data_offset, size_t data_len,
+ bool preconfounded)
+{
+ if (WARN_ON(data_offset > sg_len ||
+ data_len > sg_len ||
+ data_offset > sg_len - data_len))
+ return -EMSGSIZE;
+ return krb5->profile->encrypt(krb5, aead, sg, nr_sg, sg_len,
+ data_offset, data_len, preconfounded);
+}
+EXPORT_SYMBOL(crypto_krb5_encrypt);
+
+/**
+ * crypto_krb5_decrypt - Validate and remove Kerberos encryption and integrity.
+ * @krb5: The encoding to use.
+ * @aead: The keyed crypto object to use.
+ * @sg: Scatterlist defining the crypto buffer.
+ * @nr_sg: The number of elements in @sg.
+ * @_offset: Offset of the secure blob in the buffer; updated to data offset.
+ * @_len: The length of the secure blob; updated to data length.
+ *
+ * Using the specified Kerberos encoding, check and remove the integrity
+ * checksum and decrypt the secure region, stripping off the confounder.
+ *
+ * If successful, @_offset and @_len are updated to outline the region in which
+ * the data plus the trailing padding are stored. The caller is responsible
+ * for working out how much padding there is and removing it.
+ *
+ * Returns the 0 if successful, -ENOMEM on an allocation failure; sets
+ * *_error_code and returns -EPROTO if the data cannot be parsed, or -EBADMSG
+ * if the integrity checksum doesn't match). Other errors may also be returned
+ * from the crypto layer.
+ */
+int crypto_krb5_decrypt(const struct krb5_enctype *krb5,
+ struct crypto_aead *aead,
+ struct scatterlist *sg, unsigned int nr_sg,
+ size_t *_offset, size_t *_len)
+{
+ return krb5->profile->decrypt(krb5, aead, sg, nr_sg, _offset, _len);
+}
+EXPORT_SYMBOL(crypto_krb5_decrypt);
+
+/**
+ * crypto_krb5_get_mic - Apply Kerberos integrity checksum.
+ * @krb5: The encoding to use.
+ * @shash: The keyed hash to use.
+ * @metadata: Metadata to add into the hash before adding the data.
+ * @sg: Scatterlist defining the crypto buffer.
+ * @nr_sg: The number of elements in @sg.
+ * @sg_len: The size of the buffer.
+ * @data_offset: The offset of the data in the @sg buffer.
+ * @data_len: The length of the data.
+ *
+ * Using the specified Kerberos encoding, calculate and insert an integrity
+ * checksum into the buffer.
+ *
+ * The buffer must include space for the checksum at the front.
+ *
+ * Returns the size of the secure blob if successful, -ENOMEM on an allocation
+ * failure, -EFAULT if there is insufficient space, -EMSGSIZE if the gap for
+ * the checksum is too short. Other errors may also be returned from the
+ * crypto layer.
+ */
+ssize_t crypto_krb5_get_mic(const struct krb5_enctype *krb5,
+ struct crypto_shash *shash,
+ const struct krb5_buffer *metadata,
+ struct scatterlist *sg, unsigned int nr_sg,
+ size_t sg_len,
+ size_t data_offset, size_t data_len)
+{
+ if (WARN_ON(data_offset > sg_len ||
+ data_len > sg_len ||
+ data_offset > sg_len - data_len))
+ return -EMSGSIZE;
+ return krb5->profile->get_mic(krb5, shash, metadata, sg, nr_sg, sg_len,
+ data_offset, data_len);
+}
+EXPORT_SYMBOL(crypto_krb5_get_mic);
+
+/**
+ * crypto_krb5_verify_mic - Validate and remove Kerberos integrity checksum.
+ * @krb5: The encoding to use.
+ * @shash: The keyed hash to use.
+ * @metadata: Metadata to add into the hash before adding the data.
+ * @sg: Scatterlist defining the crypto buffer.
+ * @nr_sg: The number of elements in @sg.
+ * @_offset: Offset of the secure blob in the buffer; updated to data offset.
+ * @_len: The length of the secure blob; updated to data length.
+ *
+ * Using the specified Kerberos encoding, check and remove the integrity
+ * checksum.
+ *
+ * If successful, @_offset and @_len are updated to outline the region in which
+ * the data is stored.
+ *
+ * Returns the 0 if successful, -ENOMEM on an allocation failure; sets
+ * *_error_code and returns -EPROTO if the data cannot be parsed, or -EBADMSG
+ * if the checksum doesn't match). Other errors may also be returned from the
+ * crypto layer.
+ */
+int crypto_krb5_verify_mic(const struct krb5_enctype *krb5,
+ struct crypto_shash *shash,
+ const struct krb5_buffer *metadata,
+ struct scatterlist *sg, unsigned int nr_sg,
+ size_t *_offset, size_t *_len)
+{
+ return krb5->profile->verify_mic(krb5, shash, metadata, sg, nr_sg,
+ _offset, _len);
+}
+EXPORT_SYMBOL(crypto_krb5_verify_mic);
diff --git a/include/crypto/krb5.h b/include/crypto/krb5.h
index 94af2c558fa1..81739e9828d3 100644
--- a/include/crypto/krb5.h
+++ b/include/crypto/krb5.h
@@ -117,5 +117,26 @@ struct crypto_aead *crypto_krb5_prepare_encryption(const struct krb5_enctype *kr
struct crypto_shash *crypto_krb5_prepare_checksum(const struct krb5_enctype *krb5,
const struct krb5_buffer *TK,
u32 usage, gfp_t gfp);
+ssize_t crypto_krb5_encrypt(const struct krb5_enctype *krb5,
+ struct crypto_aead *aead,
+ struct scatterlist *sg, unsigned int nr_sg,
+ size_t sg_len,
+ size_t data_offset, size_t data_len,
+ bool preconfounded);
+int crypto_krb5_decrypt(const struct krb5_enctype *krb5,
+ struct crypto_aead *aead,
+ struct scatterlist *sg, unsigned int nr_sg,
+ size_t *_offset, size_t *_len);
+ssize_t crypto_krb5_get_mic(const struct krb5_enctype *krb5,
+ struct crypto_shash *shash,
+ const struct krb5_buffer *metadata,
+ struct scatterlist *sg, unsigned int nr_sg,
+ size_t sg_len,
+ size_t data_offset, size_t data_len);
+int crypto_krb5_verify_mic(const struct krb5_enctype *krb5,
+ struct crypto_shash *shash,
+ const struct krb5_buffer *metadata,
+ struct scatterlist *sg, unsigned int nr_sg,
+ size_t *_offset, size_t *_len);

#endif /* _CRYPTO_KRB5_H */