/* SPDX-License-Identifier: GPL-2.0-or-later */
/* Kerberos5 crypto internals
 *
 * Copyright (C) 2025 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 */

#include <linux/scatterlist.h>
#include <crypto/krb5.h>
#include <crypto/hash.h>
#include <crypto/skcipher.h>

/*
 * Profile used for key derivation and encryption.
 */
struct krb5_crypto_profile {
         /* Pseudo-random function */
        int (*calc_PRF)(const struct krb5_enctype *krb5,
                        const struct krb5_buffer *protocol_key,
                        const struct krb5_buffer *octet_string,
                        struct krb5_buffer *result,
                        gfp_t gfp);

        /* Checksum key derivation */
        int (*calc_Kc)(const struct krb5_enctype *krb5,
                       const struct krb5_buffer *TK,
                       const struct krb5_buffer *usage_constant,
                       struct krb5_buffer *Kc,
                       gfp_t gfp);

        /* Encryption key derivation */
        int (*calc_Ke)(const struct krb5_enctype *krb5,
                       const struct krb5_buffer *TK,
                       const struct krb5_buffer *usage_constant,
                       struct krb5_buffer *Ke,
                       gfp_t gfp);

         /* Integrity key derivation */
        int (*calc_Ki)(const struct krb5_enctype *krb5,
                       const struct krb5_buffer *TK,
                       const struct krb5_buffer *usage_constant,
                       struct krb5_buffer *Ki,
                       gfp_t gfp);

        /* Derive the keys needed for an encryption AEAD object. */
        int (*derive_encrypt_keys)(const struct krb5_enctype *krb5,
                                   const struct krb5_buffer *TK,
                                   unsigned int usage,
                                   struct krb5_buffer *setkey,
                                   gfp_t gfp);

        /* Directly load the keys needed for an encryption AEAD object. */
        int (*load_encrypt_keys)(const struct krb5_enctype *krb5,
                                 const struct krb5_buffer *Ke,
                                 const struct krb5_buffer *Ki,
                                 struct krb5_buffer *setkey,
                                 gfp_t gfp);

        /* Derive the key needed for a checksum hash object. */
        int (*derive_checksum_key)(const struct krb5_enctype *krb5,
                                   const struct krb5_buffer *TK,
                                   unsigned int usage,
                                   struct krb5_buffer *setkey,
                                   gfp_t gfp);

        /* Directly load the keys needed for a checksum hash object. */
        int (*load_checksum_key)(const struct krb5_enctype *krb5,
                                 const struct krb5_buffer *Kc,
                                 struct krb5_buffer *setkey,
                                 gfp_t gfp);

        /* Encrypt data in-place, inserting confounder and checksum. */
        ssize_t (*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);

        /* Decrypt data in-place, removing confounder and checksum */
        int (*decrypt)(const struct krb5_enctype *krb5,
                       struct crypto_aead *aead,
                       struct scatterlist *sg, unsigned int nr_sg,
                       size_t *_offset, size_t *_len);

        /* Generate a MIC on part of a packet, inserting the checksum */
        ssize_t (*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);

        /* Verify the MIC on a piece of data, removing the checksum */
        int (*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);
};

/*
 * Crypto size/alignment rounding convenience macros.
 */
#define crypto_roundup(X) ((unsigned int)round_up((X), CRYPTO_MINALIGN))

#define krb5_aead_size(TFM) \
        crypto_roundup(sizeof(struct aead_request) + crypto_aead_reqsize(TFM))
#define krb5_aead_ivsize(TFM) \
        crypto_roundup(crypto_aead_ivsize(TFM))
#define krb5_shash_size(TFM) \
        crypto_roundup(sizeof(struct shash_desc) + crypto_shash_descsize(TFM))
#define krb5_digest_size(TFM) \
        crypto_roundup(crypto_shash_digestsize(TFM))
#define round16(x) (((x) + 15) & ~15)

/*
 * Self-testing data.
 */
struct krb5_prf_test {
        u32 etype;
        const char *name, *key, *octet, *prf;
};

struct krb5_key_test_one {
        u32 use;
        const char *key;
};

struct krb5_key_test {
        u32 etype;
        const char *name, *key;
        struct krb5_key_test_one Kc, Ke, Ki;
};

struct krb5_enc_test {
        u32 etype;
        u32 usage;
        const char *name, *plain, *conf, *K0, *Ke, *Ki, *ct;
};

struct krb5_mic_test {
        u32 etype;
        u32 usage;
        const char *name, *plain, *K0, *Kc, *mic;
};

/*
 * krb5_api.c
 */
struct crypto_aead *krb5_prepare_encryption(const struct krb5_enctype *krb5,
                                            const struct krb5_buffer *keys,
                                            gfp_t gfp);
struct crypto_shash *krb5_prepare_checksum(const struct krb5_enctype *krb5,
                                           const struct krb5_buffer *Kc,
                                           gfp_t gfp);

/*
 * krb5_kdf.c
 */
int krb5_derive_Kc(const struct krb5_enctype *krb5, const struct krb5_buffer *TK,
                   u32 usage, struct krb5_buffer *key, gfp_t gfp);
int krb5_derive_Ke(const struct krb5_enctype *krb5, const struct krb5_buffer *TK,
                   u32 usage, struct krb5_buffer *key, gfp_t gfp);
int krb5_derive_Ki(const struct krb5_enctype *krb5, const struct krb5_buffer *TK,
                   u32 usage, struct krb5_buffer *key, gfp_t gfp);

/*
 * rfc3961_simplified.c
 */
extern const struct krb5_crypto_profile rfc3961_simplified_profile;

int crypto_shash_update_sg(struct shash_desc *desc, struct scatterlist *sg,
                           size_t offset, size_t len);
int authenc_derive_encrypt_keys(const struct krb5_enctype *krb5,
                                const struct krb5_buffer *TK,
                                unsigned int usage,
                                struct krb5_buffer *setkey,
                                gfp_t gfp);
int authenc_load_encrypt_keys(const struct krb5_enctype *krb5,
                              const struct krb5_buffer *Ke,
                              const struct krb5_buffer *Ki,
                              struct krb5_buffer *setkey,
                              gfp_t gfp);
int rfc3961_derive_checksum_key(const struct krb5_enctype *krb5,
                                const struct krb5_buffer *TK,
                                unsigned int usage,
                                struct krb5_buffer *setkey,
                                gfp_t gfp);
int rfc3961_load_checksum_key(const struct krb5_enctype *krb5,
                              const struct krb5_buffer *Kc,
                              struct krb5_buffer *setkey,
                              gfp_t gfp);
ssize_t krb5_aead_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 krb5_aead_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 rfc3961_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 rfc3961_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);

/*
 * rfc3962_aes.c
 */
extern const struct krb5_enctype krb5_aes128_cts_hmac_sha1_96;
extern const struct krb5_enctype krb5_aes256_cts_hmac_sha1_96;

/*
 * rfc6803_camellia.c
 */
extern const struct krb5_enctype krb5_camellia128_cts_cmac;
extern const struct krb5_enctype krb5_camellia256_cts_cmac;

/*
 * rfc8009_aes2.c
 */
extern const struct krb5_enctype krb5_aes128_cts_hmac_sha256_128;
extern const struct krb5_enctype krb5_aes256_cts_hmac_sha384_192;

/*
 * selftest.c
 */
#ifdef CONFIG_CRYPTO_KRB5_SELFTESTS
int krb5_selftest(void);
#else
static inline int krb5_selftest(void) { return 0; }
#endif

/*
 * selftest_data.c
 */
extern const struct krb5_prf_test krb5_prf_tests[];
extern const struct krb5_key_test krb5_key_tests[];
extern const struct krb5_enc_test krb5_enc_tests[];
extern const struct krb5_mic_test krb5_mic_tests[];