/* SPDX-License-Identifier: GPL-2.0 */
/*
 * linux/include/linux/sunrpc/auth.h
 *
 * Declarations for the RPC client authentication machinery.
 *
 * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
 */

#ifndef _LINUX_SUNRPC_AUTH_H
#define _LINUX_SUNRPC_AUTH_H

#include <linux/sunrpc/sched.h>
#include <linux/sunrpc/msg_prot.h>
#include <linux/sunrpc/xdr.h>

#include <linux/atomic.h>
#include <linux/rcupdate.h>
#include <linux/uidgid.h>
#include <linux/utsname.h>

/*
 * Maximum size of AUTH_NONE authentication information, in XDR words.
 */
#define NUL_CALLSLACK   (4)
#define NUL_REPLYSLACK  (2)

/*
 * Size of the nodename buffer. RFC1831 specifies a hard limit of 255 bytes,
 * but Linux hostnames are actually limited to __NEW_UTS_LEN bytes.
 */
#define UNX_MAXNODENAME __NEW_UTS_LEN
#define UNX_CALLSLACK   (21 + XDR_QUADLEN(UNX_MAXNODENAME))
#define UNX_NGROUPS     16

struct rpcsec_gss_info;

struct auth_cred {
        const struct cred *cred;
        const char *principal;  /* If present, this is a machine credential */
};

/*
 * Client user credentials
 */
struct rpc_auth;
struct rpc_credops;
struct rpc_cred {
        struct hlist_node       cr_hash;        /* hash chain */
        struct list_head        cr_lru;         /* lru garbage collection */
        struct rcu_head         cr_rcu;
        struct rpc_auth *       cr_auth;
        const struct rpc_credops *cr_ops;
        unsigned long           cr_expire;      /* when to gc */
        unsigned long           cr_flags;       /* various flags */
        refcount_t              cr_count;       /* ref count */
        const struct cred       *cr_cred;

        /* per-flavor data */
};
#define RPCAUTH_CRED_NEW        0
#define RPCAUTH_CRED_UPTODATE   1
#define RPCAUTH_CRED_HASHED     2
#define RPCAUTH_CRED_NEGATIVE   3

const struct cred *rpc_machine_cred(void);

/*
 * Client authentication handle
 */
struct rpc_cred_cache;
struct rpc_authops;
struct rpc_auth {
        unsigned int            au_cslack;      /* call cred size estimate */
        unsigned int            au_rslack;      /* reply cred size estimate */
        unsigned int            au_verfsize;    /* size of reply verifier */
        unsigned int            au_ralign;      /* words before UL header */

        unsigned long           au_flags;
        const struct rpc_authops *au_ops;
        rpc_authflavor_t        au_flavor;      /* pseudoflavor (note may
                                                 * differ from the flavor in
                                                 * au_ops->au_flavor in gss
                                                 * case) */
        refcount_t              au_count;       /* Reference counter */

        struct rpc_cred_cache * au_credcache;
        /* per-flavor data */
};

/* rpc_auth au_flags */
#define RPCAUTH_AUTH_DATATOUCH          (1)
#define RPCAUTH_AUTH_UPDATE_SLACK       (2)

struct rpc_auth_create_args {
        rpc_authflavor_t pseudoflavor;
        const char *target_name;
};

/* Flags for rpcauth_lookupcred() */
#define RPCAUTH_LOOKUP_NEW              0x01    /* Accept an uninitialised cred */
#define RPCAUTH_LOOKUP_ASYNC            0x02    /* Don't block waiting for memory */

/*
 * Client authentication ops
 */
struct rpc_authops {
        struct module           *owner;
        rpc_authflavor_t        au_flavor;      /* flavor (RPC_AUTH_*) */
        char *                  au_name;
        struct rpc_auth *       (*create)(const struct rpc_auth_create_args *,
                                          struct rpc_clnt *);
        void                    (*destroy)(struct rpc_auth *);

        int                     (*hash_cred)(struct auth_cred *, unsigned int);
        struct rpc_cred *       (*lookup_cred)(struct rpc_auth *, struct auth_cred *, int);
        struct rpc_cred *       (*crcreate)(struct rpc_auth*, struct auth_cred *, int, gfp_t);
        rpc_authflavor_t        (*info2flavor)(struct rpcsec_gss_info *);
        int                     (*flavor2info)(rpc_authflavor_t,
                                                struct rpcsec_gss_info *);
        int                     (*key_timeout)(struct rpc_auth *,
                                                struct rpc_cred *);
        int                     (*ping)(struct rpc_clnt *clnt);
};

struct rpc_credops {
        const char *            cr_name;        /* Name of the auth flavour */
        int                     (*cr_init)(struct rpc_auth *, struct rpc_cred *);
        void                    (*crdestroy)(struct rpc_cred *);

        int                     (*crmatch)(struct auth_cred *, struct rpc_cred *, int);
        int                     (*crmarshal)(struct rpc_task *task,
                                             struct xdr_stream *xdr);
        int                     (*crrefresh)(struct rpc_task *);
        int                     (*crvalidate)(struct rpc_task *task,
                                              struct xdr_stream *xdr);
        int                     (*crwrap_req)(struct rpc_task *task,
                                              struct xdr_stream *xdr);
        int                     (*crunwrap_resp)(struct rpc_task *task,
                                                 struct xdr_stream *xdr);
        int                     (*crkey_timeout)(struct rpc_cred *);
        char *                  (*crstringify_acceptor)(struct rpc_cred *);
        bool                    (*crneed_reencode)(struct rpc_task *);
};

extern const struct rpc_authops authunix_ops;
extern const struct rpc_authops authnull_ops;
extern const struct rpc_authops authtls_ops;

int __init              rpc_init_authunix(void);
int __init              rpcauth_init_module(void);
void                    rpcauth_remove_module(void);
void                    rpc_destroy_authunix(void);

int                     rpcauth_register(const struct rpc_authops *);
int                     rpcauth_unregister(const struct rpc_authops *);
struct rpc_auth *       rpcauth_create(const struct rpc_auth_create_args *,
                                struct rpc_clnt *);
void                    rpcauth_release(struct rpc_auth *);
rpc_authflavor_t        rpcauth_get_pseudoflavor(rpc_authflavor_t,
                                struct rpcsec_gss_info *);
int                     rpcauth_get_gssinfo(rpc_authflavor_t,
                                struct rpcsec_gss_info *);
struct rpc_cred *       rpcauth_lookup_credcache(struct rpc_auth *, struct auth_cred *, int, gfp_t);
void                    rpcauth_init_cred(struct rpc_cred *, const struct auth_cred *, struct rpc_auth *, const struct rpc_credops *);
struct rpc_cred *       rpcauth_lookupcred(struct rpc_auth *, int);
void                    put_rpccred(struct rpc_cred *);
int                     rpcauth_marshcred(struct rpc_task *task,
                                          struct xdr_stream *xdr);
int                     rpcauth_checkverf(struct rpc_task *task,
                                          struct xdr_stream *xdr);
int                     rpcauth_wrap_req_encode(struct rpc_task *task,
                                                struct xdr_stream *xdr);
int                     rpcauth_wrap_req(struct rpc_task *task,
                                         struct xdr_stream *xdr);
int                     rpcauth_unwrap_resp_decode(struct rpc_task *task,
                                                   struct xdr_stream *xdr);
int                     rpcauth_unwrap_resp(struct rpc_task *task,
                                            struct xdr_stream *xdr);
bool                    rpcauth_xmit_need_reencode(struct rpc_task *task);
int                     rpcauth_refreshcred(struct rpc_task *);
void                    rpcauth_invalcred(struct rpc_task *);
int                     rpcauth_uptodatecred(struct rpc_task *);
int                     rpcauth_init_credcache(struct rpc_auth *);
void                    rpcauth_destroy_credcache(struct rpc_auth *);
void                    rpcauth_clear_credcache(struct rpc_cred_cache *);
char *                  rpcauth_stringify_acceptor(struct rpc_cred *);

static inline
struct rpc_cred *get_rpccred(struct rpc_cred *cred)
{
        if (cred != NULL && refcount_inc_not_zero(&cred->cr_count))
                return cred;
        return NULL;
}

#endif /* _LINUX_SUNRPC_AUTH_H */