/* SPDX-License-Identifier: GPL-2.0 or BSD-3-Clause */
/*
 * SunRPC GSS Kerberos 5 mechanism internal definitions
 *
 * Copyright (c) 2022 Oracle and/or its affiliates.
 */

#ifndef _NET_SUNRPC_AUTH_GSS_KRB5_INTERNAL_H
#define _NET_SUNRPC_AUTH_GSS_KRB5_INTERNAL_H

/*
 * The RFCs often specify payload lengths in bits. This helper
 * converts a specified bit-length to the number of octets/bytes.
 */
#define BITS2OCTETS(x)  ((x) / 8)

struct krb5_ctx;

struct gss_krb5_enctype {
        const u32               etype;          /* encryption (key) type */
        const u32               ctype;          /* checksum type */
        const char              *name;          /* "friendly" name */
        const char              *encrypt_name;  /* crypto encrypt name */
        const char              *aux_cipher;    /* aux encrypt cipher name */
        const char              *cksum_name;    /* crypto checksum name */
        const u16               signalg;        /* signing algorithm */
        const u16               sealalg;        /* sealing algorithm */
        const u32               cksumlength;    /* checksum length */
        const u32               keyed_cksum;    /* is it a keyed cksum? */
        const u32               keybytes;       /* raw key len, in bytes */
        const u32               keylength;      /* protocol key length, in octets */
        const u32               Kc_length;      /* checksum subkey length, in octets */
        const u32               Ke_length;      /* encryption subkey length, in octets */
        const u32               Ki_length;      /* integrity subkey length, in octets */

        int (*derive_key)(const struct gss_krb5_enctype *gk5e,
                          const struct xdr_netobj *in,
                          struct xdr_netobj *out,
                          const struct xdr_netobj *label,
                          gfp_t gfp_mask);
        u32 (*encrypt)(struct krb5_ctx *kctx, u32 offset,
                       struct xdr_buf *buf, struct page **pages);
        u32 (*decrypt)(struct krb5_ctx *kctx, u32 offset, u32 len,
                       struct xdr_buf *buf, u32 *headskip, u32 *tailskip);
        u32 (*get_mic)(struct krb5_ctx *kctx, struct xdr_buf *text,
                       struct xdr_netobj *token);
        u32 (*verify_mic)(struct krb5_ctx *kctx, struct xdr_buf *message_buffer,
                          struct xdr_netobj *read_token);
        u32 (*wrap)(struct krb5_ctx *kctx, int offset,
                    struct xdr_buf *buf, struct page **pages);
        u32 (*unwrap)(struct krb5_ctx *kctx, int offset, int len,
                      struct xdr_buf *buf, unsigned int *slack,
                      unsigned int *align);
};

/* krb5_ctx flags definitions */
#define KRB5_CTX_FLAG_INITIATOR         0x00000001
#define KRB5_CTX_FLAG_ACCEPTOR_SUBKEY   0x00000004

struct krb5_ctx {
        int                     initiate; /* 1 = initiating, 0 = accepting */
        u32                     enctype;
        u32                     flags;
        const struct gss_krb5_enctype *gk5e; /* enctype-specific info */
        struct crypto_sync_skcipher *enc;
        struct crypto_sync_skcipher *seq;
        struct crypto_sync_skcipher *acceptor_enc;
        struct crypto_sync_skcipher *initiator_enc;
        struct crypto_sync_skcipher *acceptor_enc_aux;
        struct crypto_sync_skcipher *initiator_enc_aux;
        struct crypto_ahash     *acceptor_sign;
        struct crypto_ahash     *initiator_sign;
        struct crypto_ahash     *initiator_integ;
        struct crypto_ahash     *acceptor_integ;
        u8                      Ksess[GSS_KRB5_MAX_KEYLEN]; /* session key */
        u8                      cksum[GSS_KRB5_MAX_KEYLEN];
        atomic_t                seq_send;
        atomic64_t              seq_send64;
        time64_t                endtime;
        struct xdr_netobj       mech_used;
};

/*
 * GSS Kerberos 5 mechanism Per-Message calls.
 */

u32 gss_krb5_get_mic_v2(struct krb5_ctx *ctx, struct xdr_buf *text,
                        struct xdr_netobj *token);

u32 gss_krb5_verify_mic_v2(struct krb5_ctx *ctx, struct xdr_buf *message_buffer,
                           struct xdr_netobj *read_token);

u32 gss_krb5_wrap_v2(struct krb5_ctx *kctx, int offset,
                     struct xdr_buf *buf, struct page **pages);

u32 gss_krb5_unwrap_v2(struct krb5_ctx *kctx, int offset, int len,
                       struct xdr_buf *buf, unsigned int *slack,
                       unsigned int *align);

/*
 * Implementation internal functions
 */

/* Key Derivation Functions */

int krb5_derive_key_v2(const struct gss_krb5_enctype *gk5e,
                       const struct xdr_netobj *inkey,
                       struct xdr_netobj *outkey,
                       const struct xdr_netobj *label,
                       gfp_t gfp_mask);

int krb5_kdf_hmac_sha2(const struct gss_krb5_enctype *gk5e,
                       const struct xdr_netobj *inkey,
                       struct xdr_netobj *outkey,
                       const struct xdr_netobj *in_constant,
                       gfp_t gfp_mask);

int krb5_kdf_feedback_cmac(const struct gss_krb5_enctype *gk5e,
                           const struct xdr_netobj *inkey,
                           struct xdr_netobj *outkey,
                           const struct xdr_netobj *in_constant,
                           gfp_t gfp_mask);

/**
 * krb5_derive_key - Derive a subkey from a protocol key
 * @kctx: Kerberos 5 context
 * @inkey: base protocol key
 * @outkey: OUT: derived key
 * @usage: key usage value
 * @seed: key usage seed (one octet)
 * @gfp_mask: memory allocation control flags
 *
 * Caller sets @outkey->len to the desired length of the derived key.
 *
 * On success, returns 0 and fills in @outkey. A negative errno value
 * is returned on failure.
 */
static inline int krb5_derive_key(struct krb5_ctx *kctx,
                                  const struct xdr_netobj *inkey,
                                  struct xdr_netobj *outkey,
                                  u32 usage, u8 seed, gfp_t gfp_mask)
{
        const struct gss_krb5_enctype *gk5e = kctx->gk5e;
        u8 label_data[GSS_KRB5_K5CLENGTH];
        struct xdr_netobj label = {
                .len    = sizeof(label_data),
                .data   = label_data,
        };
        __be32 *p = (__be32 *)label_data;

        *p = cpu_to_be32(usage);
        label_data[4] = seed;
        return gk5e->derive_key(gk5e, inkey, outkey, &label, gfp_mask);
}

void krb5_make_confounder(u8 *p, int conflen);

u32 gss_krb5_checksum(struct crypto_ahash *tfm, char *header, int hdrlen,
                      const struct xdr_buf *body, int body_offset,
                      struct xdr_netobj *cksumout);

u32 krb5_encrypt(struct crypto_sync_skcipher *key, void *iv, void *in,
                 void *out, int length);

int xdr_extend_head(struct xdr_buf *buf, unsigned int base,
                    unsigned int shiftlen);

u32 gss_krb5_aes_encrypt(struct krb5_ctx *kctx, u32 offset,
                         struct xdr_buf *buf, struct page **pages);

u32 gss_krb5_aes_decrypt(struct krb5_ctx *kctx, u32 offset, u32 len,
                         struct xdr_buf *buf, u32 *plainoffset, u32 *plainlen);

u32 krb5_etm_encrypt(struct krb5_ctx *kctx, u32 offset, struct xdr_buf *buf,
                     struct page **pages);

u32 krb5_etm_decrypt(struct krb5_ctx *kctx, u32 offset, u32 len,
                     struct xdr_buf *buf, u32 *headskip, u32 *tailskip);

#if IS_ENABLED(CONFIG_KUNIT)
void krb5_nfold(u32 inbits, const u8 *in, u32 outbits, u8 *out);
const struct gss_krb5_enctype *gss_krb5_lookup_enctype(u32 etype);
int krb5_cbc_cts_encrypt(struct crypto_sync_skcipher *cts_tfm,
                         struct crypto_sync_skcipher *cbc_tfm, u32 offset,
                         struct xdr_buf *buf, struct page **pages,
                         u8 *iv, unsigned int ivsize);
int krb5_cbc_cts_decrypt(struct crypto_sync_skcipher *cts_tfm,
                         struct crypto_sync_skcipher *cbc_tfm,
                         u32 offset, struct xdr_buf *buf);
u32 krb5_etm_checksum(struct crypto_sync_skcipher *cipher,
                      struct crypto_ahash *tfm, const struct xdr_buf *body,
                      int body_offset, struct xdr_netobj *cksumout);
#endif

#endif /* _NET_SUNRPC_AUTH_GSS_KRB5_INTERNAL_H */