/* SPDX-License-Identifier: GPL-2.0 */
/*
 * linux/include/linux/sunrpc/svc.h
 *
 * RPC server declarations.
 *
 * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
 */


#ifndef SUNRPC_SVC_H
#define SUNRPC_SVC_H

#include <linux/in.h>
#include <linux/in6.h>
#include <linux/sunrpc/types.h>
#include <linux/sunrpc/xdr.h>
#include <linux/sunrpc/auth.h>
#include <linux/sunrpc/svcauth.h>
#include <linux/wait.h>
#include <linux/mm.h>

/* statistics for svc_pool structures */
struct svc_pool_stats {
        atomic_long_t   packets;
        unsigned long   sockets_queued;
        atomic_long_t   threads_woken;
        atomic_long_t   threads_timedout;
};

/*
 *
 * RPC service thread pool.
 *
 * Pool of threads and temporary sockets.  Generally there is only
 * a single one of these per RPC service, but on NUMA machines those
 * services that can benefit from it (i.e. nfs but not lockd) will
 * have one pool per NUMA node.  This optimisation reduces cross-
 * node traffic on multi-node NUMA NFS servers.
 */
struct svc_pool {
        unsigned int            sp_id;          /* pool id; also node id on NUMA */
        spinlock_t              sp_lock;        /* protects all fields */
        struct list_head        sp_sockets;     /* pending sockets */
        unsigned int            sp_nrthreads;   /* # of threads in pool */
        struct list_head        sp_all_threads; /* all server threads */
        struct svc_pool_stats   sp_stats;       /* statistics on pool operation */
#define SP_TASK_PENDING         (0)             /* still work to do even if no
                                                 * xprt is queued. */
#define SP_CONGESTED            (1)
        unsigned long           sp_flags;
} ____cacheline_aligned_in_smp;

struct svc_serv;

struct svc_serv_ops {
        /* Callback to use when last thread exits. */
        void            (*svo_shutdown)(struct svc_serv *, struct net *);

        /* function for service threads to run */
        int             (*svo_function)(void *);

        /* queue up a transport for servicing */
        void            (*svo_enqueue_xprt)(struct svc_xprt *);

        /* set up thread (or whatever) execution context */
        int             (*svo_setup)(struct svc_serv *, struct svc_pool *, int);

        /* optional module to count when adding threads (pooled svcs only) */
        struct module   *svo_module;
};

/*
 * RPC service.
 *
 * An RPC service is a ``daemon,'' possibly multithreaded, which
 * receives and processes incoming RPC messages.
 * It has one or more transport sockets associated with it, and maintains
 * a list of idle threads waiting for input.
 *
 * We currently do not support more than one RPC program per daemon.
 */
struct svc_serv {
        struct svc_program *    sv_program;     /* RPC program */
        struct svc_stat *       sv_stats;       /* RPC statistics */
        spinlock_t              sv_lock;
        unsigned int            sv_nrthreads;   /* # of server threads */
        unsigned int            sv_maxconn;     /* max connections allowed or
                                                 * '0' causing max to be based
                                                 * on number of threads. */

        unsigned int            sv_max_payload; /* datagram payload size */
        unsigned int            sv_max_mesg;    /* max_payload + 1 page for overheads */
        unsigned int            sv_xdrsize;     /* XDR buffer size */
        struct list_head        sv_permsocks;   /* all permanent sockets */
        struct list_head        sv_tempsocks;   /* all temporary sockets */
        int                     sv_tmpcnt;      /* count of temporary sockets */
        struct timer_list       sv_temptimer;   /* timer for aging temporary sockets */

        char *                  sv_name;        /* service name */

        unsigned int            sv_nrpools;     /* number of thread pools */
        struct svc_pool *       sv_pools;       /* array of thread pools */
        const struct svc_serv_ops *sv_ops;      /* server operations */
#if defined(CONFIG_SUNRPC_BACKCHANNEL)
        struct list_head        sv_cb_list;     /* queue for callback requests
                                                 * that arrive over the same
                                                 * connection */
        spinlock_t              sv_cb_lock;     /* protects the svc_cb_list */
        wait_queue_head_t       sv_cb_waitq;    /* sleep here if there are no
                                                 * entries in the svc_cb_list */
        bool                    sv_bc_enabled;  /* service uses backchannel */
#endif /* CONFIG_SUNRPC_BACKCHANNEL */
};

/*
 * We use sv_nrthreads as a reference count.  svc_destroy() drops
 * this refcount, so we need to bump it up around operations that
 * change the number of threads.  Horrible, but there it is.
 * Should be called with the "service mutex" held.
 */
static inline void svc_get(struct svc_serv *serv)
{
        serv->sv_nrthreads++;
}

/*
 * Maximum payload size supported by a kernel RPC server.
 * This is use to determine the max number of pages nfsd is
 * willing to return in a single READ operation.
 *
 * These happen to all be powers of 2, which is not strictly
 * necessary but helps enforce the real limitation, which is
 * that they should be multiples of PAGE_SIZE.
 *
 * For UDP transports, a block plus NFS,RPC, and UDP headers
 * has to fit into the IP datagram limit of 64K.  The largest
 * feasible number for all known page sizes is probably 48K,
 * but we choose 32K here.  This is the same as the historical
 * Linux limit; someone who cares more about NFS/UDP performance
 * can test a larger number.
 *
 * For TCP transports we have more freedom.  A size of 1MB is
 * chosen to match the client limit.  Other OSes are known to
 * have larger limits, but those numbers are probably beyond
 * the point of diminishing returns.
 */
#define RPCSVC_MAXPAYLOAD       (1*1024*1024u)
#define RPCSVC_MAXPAYLOAD_TCP   RPCSVC_MAXPAYLOAD
#define RPCSVC_MAXPAYLOAD_UDP   (32*1024u)

extern u32 svc_max_payload(const struct svc_rqst *rqstp);

/*
 * RPC Requsts and replies are stored in one or more pages.
 * We maintain an array of pages for each server thread.
 * Requests are copied into these pages as they arrive.  Remaining
 * pages are available to write the reply into.
 *
 * Pages are sent using ->sendpage so each server thread needs to
 * allocate more to replace those used in sending.  To help keep track
 * of these pages we have a receive list where all pages initialy live,
 * and a send list where pages are moved to when there are to be part
 * of a reply.
 *
 * We use xdr_buf for holding responses as it fits well with NFS
 * read responses (that have a header, and some data pages, and possibly
 * a tail) and means we can share some client side routines.
 *
 * The xdr_buf.head kvec always points to the first page in the rq_*pages
 * list.  The xdr_buf.pages pointer points to the second page on that
 * list.  xdr_buf.tail points to the end of the first page.
 * This assumes that the non-page part of an rpc reply will fit
 * in a page - NFSd ensures this.  lockd also has no trouble.
 *
 * Each request/reply pair can have at most one "payload", plus two pages,
 * one for the request, and one for the reply.
 * We using ->sendfile to return read data, we might need one extra page
 * if the request is not page-aligned.  So add another '1'.
 */
#define RPCSVC_MAXPAGES         ((RPCSVC_MAXPAYLOAD+PAGE_SIZE-1)/PAGE_SIZE \
                                + 2 + 1)

static inline u32 svc_getnl(struct kvec *iov)
{
        __be32 val, *vp;
        vp = iov->iov_base;
        val = *vp++;
        iov->iov_base = (void*)vp;
        iov->iov_len -= sizeof(__be32);
        return ntohl(val);
}

static inline void svc_putnl(struct kvec *iov, u32 val)
{
        __be32 *vp = iov->iov_base + iov->iov_len;
        *vp = htonl(val);
        iov->iov_len += sizeof(__be32);
}

static inline __be32 svc_getu32(struct kvec *iov)
{
        __be32 val, *vp;
        vp = iov->iov_base;
        val = *vp++;
        iov->iov_base = (void*)vp;
        iov->iov_len -= sizeof(__be32);
        return val;
}

static inline void svc_ungetu32(struct kvec *iov)
{
        __be32 *vp = (__be32 *)iov->iov_base;
        iov->iov_base = (void *)(vp - 1);
        iov->iov_len += sizeof(*vp);
}

static inline void svc_putu32(struct kvec *iov, __be32 val)
{
        __be32 *vp = iov->iov_base + iov->iov_len;
        *vp = val;
        iov->iov_len += sizeof(__be32);
}

/*
 * The context of a single thread, including the request currently being
 * processed.
 */
struct svc_rqst {
        struct list_head        rq_all;         /* all threads list */
        struct rcu_head         rq_rcu_head;    /* for RCU deferred kfree */
        struct svc_xprt *       rq_xprt;        /* transport ptr */

        struct sockaddr_storage rq_addr;        /* peer address */
        size_t                  rq_addrlen;
        struct sockaddr_storage rq_daddr;       /* dest addr of request
                                                 *  - reply from here */
        size_t                  rq_daddrlen;

        struct svc_serv *       rq_server;      /* RPC service definition */
        struct svc_pool *       rq_pool;        /* thread pool */
        const struct svc_procedure *rq_procinfo;/* procedure info */
        struct auth_ops *       rq_authop;      /* authentication flavour */
        struct svc_cred         rq_cred;        /* auth info */
        void *                  rq_xprt_ctxt;   /* transport specific context ptr */
        struct svc_deferred_req*rq_deferred;    /* deferred request we are replaying */

        size_t                  rq_xprt_hlen;   /* xprt header len */
        struct xdr_buf          rq_arg;
        struct xdr_buf          rq_res;
        struct page             *rq_pages[RPCSVC_MAXPAGES + 1];
        struct page *           *rq_respages;   /* points into rq_pages */
        struct page *           *rq_next_page; /* next reply page to use */
        struct page *           *rq_page_end;  /* one past the last page */

        struct kvec             rq_vec[RPCSVC_MAXPAGES]; /* generally useful.. */

        __be32                  rq_xid;         /* transmission id */
        u32                     rq_prog;        /* program number */
        u32                     rq_vers;        /* program version */
        u32                     rq_proc;        /* procedure number */
        u32                     rq_prot;        /* IP protocol */
        int                     rq_cachetype;   /* catering to nfsd */
#define RQ_SECURE       (0)                     /* secure port */
#define RQ_LOCAL        (1)                     /* local request */
#define RQ_USEDEFERRAL  (2)                     /* use deferral */
#define RQ_DROPME       (3)                     /* drop current reply */
#define RQ_SPLICE_OK    (4)                     /* turned off in gss privacy
                                                 * to prevent encrypting page
                                                 * cache pages */
#define RQ_VICTIM       (5)                     /* about to be shut down */
#define RQ_BUSY         (6)                     /* request is busy */
#define RQ_DATA         (7)                     /* request has data */
        unsigned long           rq_flags;       /* flags field */
        ktime_t                 rq_qtime;       /* enqueue time */

        void *                  rq_argp;        /* decoded arguments */
        void *                  rq_resp;        /* xdr'd results */
        void *                  rq_auth_data;   /* flavor-specific data */
        int                     rq_auth_slack;  /* extra space xdr code
                                                 * should leave in head
                                                 * for krb5i, krb5p.
                                                 */
        int                     rq_reserved;    /* space on socket outq
                                                 * reserved for this request
                                                 */
        ktime_t                 rq_stime;       /* start time */

        struct cache_req        rq_chandle;     /* handle passed to caches for 
                                                 * request delaying 
                                                 */
        /* Catering to nfsd */
        struct auth_domain *    rq_client;      /* RPC peer info */
        struct auth_domain *    rq_gssclient;   /* "gss/"-style peer info */
        struct svc_cacherep *   rq_cacherep;    /* cache info */
        struct task_struct      *rq_task;       /* service thread */
        spinlock_t              rq_lock;        /* per-request lock */
        struct net              *rq_bc_net;     /* pointer to backchannel's
                                                 * net namespace
                                                 */
};

#define SVC_NET(rqst) (rqst->rq_xprt ? rqst->rq_xprt->xpt_net : rqst->rq_bc_net)

/*
 * Rigorous type checking on sockaddr type conversions
 */
static inline struct sockaddr_in *svc_addr_in(const struct svc_rqst *rqst)
{
        return (struct sockaddr_in *) &rqst->rq_addr;
}

static inline struct sockaddr_in6 *svc_addr_in6(const struct svc_rqst *rqst)
{
        return (struct sockaddr_in6 *) &rqst->rq_addr;
}

static inline struct sockaddr *svc_addr(const struct svc_rqst *rqst)
{
        return (struct sockaddr *) &rqst->rq_addr;
}

static inline struct sockaddr_in *svc_daddr_in(const struct svc_rqst *rqst)
{
        return (struct sockaddr_in *) &rqst->rq_daddr;
}

static inline struct sockaddr_in6 *svc_daddr_in6(const struct svc_rqst *rqst)
{
        return (struct sockaddr_in6 *) &rqst->rq_daddr;
}

static inline struct sockaddr *svc_daddr(const struct svc_rqst *rqst)
{
        return (struct sockaddr *) &rqst->rq_daddr;
}

/*
 * Check buffer bounds after decoding arguments
 */
static inline int
xdr_argsize_check(struct svc_rqst *rqstp, __be32 *p)
{
        char *cp = (char *)p;
        struct kvec *vec = &rqstp->rq_arg.head[0];
        return cp >= (char*)vec->iov_base
                && cp <= (char*)vec->iov_base + vec->iov_len;
}

static inline int
xdr_ressize_check(struct svc_rqst *rqstp, __be32 *p)
{
        struct kvec *vec = &rqstp->rq_res.head[0];
        char *cp = (char*)p;

        vec->iov_len = cp - (char*)vec->iov_base;

        return vec->iov_len <= PAGE_SIZE;
}

static inline void svc_free_res_pages(struct svc_rqst *rqstp)
{
        while (rqstp->rq_next_page != rqstp->rq_respages) {
                struct page **pp = --rqstp->rq_next_page;
                if (*pp) {
                        put_page(*pp);
                        *pp = NULL;
                }
        }
}

struct svc_deferred_req {
        u32                     prot;   /* protocol (UDP or TCP) */
        struct svc_xprt         *xprt;
        struct sockaddr_storage addr;   /* where reply must go */
        size_t                  addrlen;
        struct sockaddr_storage daddr;  /* where reply must come from */
        size_t                  daddrlen;
        struct cache_deferred_req handle;
        size_t                  xprt_hlen;
        int                     argslen;
        __be32                  args[0];
};

/*
 * List of RPC programs on the same transport endpoint
 */
struct svc_program {
        struct svc_program *    pg_next;        /* other programs (same xprt) */
        u32                     pg_prog;        /* program number */
        unsigned int            pg_lovers;      /* lowest version */
        unsigned int            pg_hivers;      /* highest version */
        unsigned int            pg_nvers;       /* number of versions */
        const struct svc_version **pg_vers;     /* version array */
        char *                  pg_name;        /* service name */
        char *                  pg_class;       /* class name: services sharing authentication */
        struct svc_stat *       pg_stats;       /* rpc statistics */
        int                     (*pg_authenticate)(struct svc_rqst *);
};

/*
 * RPC program version
 */
struct svc_version {
        u32                     vs_vers;        /* version number */
        u32                     vs_nproc;       /* number of procedures */
        const struct svc_procedure *vs_proc;    /* per-procedure info */
        unsigned int            *vs_count;      /* call counts */
        u32                     vs_xdrsize;     /* xdrsize needed for this version */

        /* Don't register with rpcbind */
        bool                    vs_hidden;

        /* Don't care if the rpcbind registration fails */
        bool                    vs_rpcb_optnl;

        /* Need xprt with congestion control */
        bool                    vs_need_cong_ctrl;

        /* Override dispatch function (e.g. when caching replies).
         * A return value of 0 means drop the request. 
         * vs_dispatch == NULL means use default dispatcher.
         */
        int                     (*vs_dispatch)(struct svc_rqst *, __be32 *);
};

/*
 * RPC procedure info
 */
struct svc_procedure {
        /* process the request: */
        __be32                  (*pc_func)(struct svc_rqst *);
        /* XDR decode args: */
        int                     (*pc_decode)(struct svc_rqst *, __be32 *data);
        /* XDR encode result: */
        int                     (*pc_encode)(struct svc_rqst *, __be32 *data);
        /* XDR free result: */
        void                    (*pc_release)(struct svc_rqst *);
        unsigned int            pc_argsize;     /* argument struct size */
        unsigned int            pc_ressize;     /* result struct size */
        unsigned int            pc_cachetype;   /* cache info (NFS) */
        unsigned int            pc_xdrressize;  /* maximum size of XDR reply */
};

/*
 * Mode for mapping cpus to pools.
 */
enum {
        SVC_POOL_AUTO = -1,     /* choose one of the others */
        SVC_POOL_GLOBAL,        /* no mapping, just a single global pool
                                 * (legacy & UP mode) */
        SVC_POOL_PERCPU,        /* one pool per cpu */
        SVC_POOL_PERNODE        /* one pool per numa node */
};

struct svc_pool_map {
        int count;                      /* How many svc_servs use us */
        int mode;                       /* Note: int not enum to avoid
                                         * warnings about "enumeration value
                                         * not handled in switch" */
        unsigned int npools;
        unsigned int *pool_to;          /* maps pool id to cpu or node */
        unsigned int *to_pool;          /* maps cpu or node to pool id */
};

extern struct svc_pool_map svc_pool_map;

/*
 * Function prototypes.
 */
int svc_rpcb_setup(struct svc_serv *serv, struct net *net);
void svc_rpcb_cleanup(struct svc_serv *serv, struct net *net);
int svc_bind(struct svc_serv *serv, struct net *net);
struct svc_serv *svc_create(struct svc_program *, unsigned int,
                            const struct svc_serv_ops *);
struct svc_rqst *svc_rqst_alloc(struct svc_serv *serv,
                                        struct svc_pool *pool, int node);
struct svc_rqst *svc_prepare_thread(struct svc_serv *serv,
                                        struct svc_pool *pool, int node);
void               svc_rqst_free(struct svc_rqst *);
void               svc_exit_thread(struct svc_rqst *);
unsigned int       svc_pool_map_get(void);
void               svc_pool_map_put(void);
struct svc_serv *  svc_create_pooled(struct svc_program *, unsigned int,
                        const struct svc_serv_ops *);
int                svc_set_num_threads(struct svc_serv *, struct svc_pool *, int);
int                svc_set_num_threads_sync(struct svc_serv *, struct svc_pool *, int);
int                svc_pool_stats_open(struct svc_serv *serv, struct file *file);
void               svc_destroy(struct svc_serv *);
void               svc_shutdown_net(struct svc_serv *, struct net *);
int                svc_process(struct svc_rqst *);
int                bc_svc_process(struct svc_serv *, struct rpc_rqst *,
                        struct svc_rqst *);
int                svc_register(const struct svc_serv *, struct net *, const int,
                                const unsigned short, const unsigned short);

void               svc_wake_up(struct svc_serv *);
void               svc_reserve(struct svc_rqst *rqstp, int space);
struct svc_pool *  svc_pool_for_cpu(struct svc_serv *serv, int cpu);
char *             svc_print_addr(struct svc_rqst *, char *, size_t);
unsigned int       svc_fill_write_vector(struct svc_rqst *rqstp,
                                         struct page **pages,
                                         struct kvec *first, size_t total);
char              *svc_fill_symlink_pathname(struct svc_rqst *rqstp,
                                             struct kvec *first, void *p,
                                             size_t total);

#define RPC_MAX_ADDRBUFLEN      (63U)

/*
 * When we want to reduce the size of the reserved space in the response
 * buffer, we need to take into account the size of any checksum data that
 * may be at the end of the packet. This is difficult to determine exactly
 * for all cases without actually generating the checksum, so we just use a
 * static value.
 */
static inline void svc_reserve_auth(struct svc_rqst *rqstp, int space)
{
        svc_reserve(rqstp, space + rqstp->rq_auth_slack);
}

#endif /* SUNRPC_SVC_H */