// SPDX-License-Identifier: GPL-2.0
/*
 * In-kernel MOUNT protocol client
 *
 * Copyright (C) 1997, Olaf Kirch <okir@monad.swb.de>
 */

#include <linux/types.h>
#include <linux/socket.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/uio.h>
#include <linux/net.h>
#include <linux/in.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/sched.h>
#include <linux/nfs_fs.h>
#include "internal.h"

#define NFSDBG_FACILITY NFSDBG_MOUNT

/*
 * Defined by RFC 1094, section A.3; and RFC 1813, section 5.1.4
 */
#define MNTPATHLEN              (1024)

/*
 * XDR data type sizes
 */
#define encode_dirpath_sz       (1 + XDR_QUADLEN(MNTPATHLEN))
#define MNT_status_sz           (1)
#define MNT_fhandle_sz          XDR_QUADLEN(NFS2_FHSIZE)
#define MNT_fhandlev3_sz        XDR_QUADLEN(NFS3_FHSIZE)
#define MNT_authflav3_sz        (1 + NFS_MAX_SECFLAVORS)

/*
 * XDR argument and result sizes
 */
#define MNT_enc_dirpath_sz      encode_dirpath_sz
#define MNT_dec_mountres_sz     (MNT_status_sz + MNT_fhandle_sz)
#define MNT_dec_mountres3_sz    (MNT_status_sz + MNT_fhandlev3_sz + \
                                 MNT_authflav3_sz)

/*
 * Defined by RFC 1094, section A.5
 */
enum {
        MOUNTPROC_NULL          = 0,
        MOUNTPROC_MNT           = 1,
        MOUNTPROC_DUMP          = 2,
        MOUNTPROC_UMNT          = 3,
        MOUNTPROC_UMNTALL       = 4,
        MOUNTPROC_EXPORT        = 5,
};

/*
 * Defined by RFC 1813, section 5.2
 */
enum {
        MOUNTPROC3_NULL         = 0,
        MOUNTPROC3_MNT          = 1,
        MOUNTPROC3_DUMP         = 2,
        MOUNTPROC3_UMNT         = 3,
        MOUNTPROC3_UMNTALL      = 4,
        MOUNTPROC3_EXPORT       = 5,
};

static const struct rpc_program mnt_program;

/*
 * Defined by OpenGroup XNFS Version 3W, chapter 8
 */
enum mountstat {
        MNT_OK                  = 0,
        MNT_EPERM               = 1,
        MNT_ENOENT              = 2,
        MNT_EACCES              = 13,
        MNT_EINVAL              = 22,
};

static struct {
        u32 status;
        int errno;
} mnt_errtbl[] = {
        { .status = MNT_OK,                     .errno = 0,             },
        { .status = MNT_EPERM,                  .errno = -EPERM,        },
        { .status = MNT_ENOENT,                 .errno = -ENOENT,       },
        { .status = MNT_EACCES,                 .errno = -EACCES,       },
        { .status = MNT_EINVAL,                 .errno = -EINVAL,       },
};

/*
 * Defined by RFC 1813, section 5.1.5
 */
enum mountstat3 {
        MNT3_OK                 = 0,            /* no error */
        MNT3ERR_PERM            = 1,            /* Not owner */
        MNT3ERR_NOENT           = 2,            /* No such file or directory */
        MNT3ERR_IO              = 5,            /* I/O error */
        MNT3ERR_ACCES           = 13,           /* Permission denied */
        MNT3ERR_NOTDIR          = 20,           /* Not a directory */
        MNT3ERR_INVAL           = 22,           /* Invalid argument */
        MNT3ERR_NAMETOOLONG     = 63,           /* Filename too long */
        MNT3ERR_NOTSUPP         = 10004,        /* Operation not supported */
        MNT3ERR_SERVERFAULT     = 10006,        /* A failure on the server */
};

static struct {
        u32 status;
        int errno;
} mnt3_errtbl[] = {
        { .status = MNT3_OK,                    .errno = 0,             },
        { .status = MNT3ERR_PERM,               .errno = -EPERM,        },
        { .status = MNT3ERR_NOENT,              .errno = -ENOENT,       },
        { .status = MNT3ERR_IO,                 .errno = -EIO,          },
        { .status = MNT3ERR_ACCES,              .errno = -EACCES,       },
        { .status = MNT3ERR_NOTDIR,             .errno = -ENOTDIR,      },
        { .status = MNT3ERR_INVAL,              .errno = -EINVAL,       },
        { .status = MNT3ERR_NAMETOOLONG,        .errno = -ENAMETOOLONG, },
        { .status = MNT3ERR_NOTSUPP,            .errno = -ENOTSUPP,     },
        { .status = MNT3ERR_SERVERFAULT,        .errno = -EREMOTEIO,    },
};

struct mountres {
        int errno;
        struct nfs_fh *fh;
        unsigned int *auth_count;
        rpc_authflavor_t *auth_flavors;
};

/**
 * nfs_mount - Obtain an NFS file handle for the given host and path
 * @info: pointer to mount request arguments
 * @timeo: deciseconds the mount waits for a response before it retries
 * @retrans: number of times the mount retries a request
 *
 * Uses timeout parameters specified by caller. On successful return, the
 * auth_flavs list and auth_flav_len will be populated with the list from the
 * server or a faked-up list if the server didn't provide one.
 */
int nfs_mount(struct nfs_mount_request *info, int timeo, int retrans)
{
        struct rpc_timeout mnt_timeout;
        struct mountres result = {
                .fh             = info->fh,
                .auth_count     = info->auth_flav_len,
                .auth_flavors   = info->auth_flavs,
        };
        struct rpc_message msg  = {
                .rpc_argp       = info->dirpath,
                .rpc_resp       = &result,
        };
        struct rpc_create_args args = {
                .net            = info->net,
                .protocol       = info->protocol,
                .address        = (struct sockaddr *)info->sap,
                .addrsize       = info->salen,
                .timeout        = &mnt_timeout,
                .servername     = info->hostname,
                .program        = &mnt_program,
                .version        = info->version,
                .authflavor     = RPC_AUTH_UNIX,
                .cred           = current_cred(),
        };
        struct rpc_clnt         *mnt_clnt;
        int                     status;

        dprintk("NFS: sending MNT request for %s:%s\n",
                (info->hostname ? info->hostname : "server"),
                        info->dirpath);

        if (strlen(info->dirpath) > MNTPATHLEN)
                return -ENAMETOOLONG;

        if (info->noresvport)
                args.flags |= RPC_CLNT_CREATE_NONPRIVPORT;

        nfs_init_timeout_values(&mnt_timeout, info->protocol, timeo, retrans);
        mnt_clnt = rpc_create(&args);
        if (IS_ERR(mnt_clnt))
                goto out_clnt_err;

        if (info->version == NFS_MNT3_VERSION)
                msg.rpc_proc = &mnt_clnt->cl_procinfo[MOUNTPROC3_MNT];
        else
                msg.rpc_proc = &mnt_clnt->cl_procinfo[MOUNTPROC_MNT];

        status = rpc_call_sync(mnt_clnt, &msg, RPC_TASK_SOFT|RPC_TASK_TIMEOUT);
        rpc_shutdown_client(mnt_clnt);

        if (status < 0)
                goto out_call_err;
        if (result.errno != 0)
                goto out_mnt_err;

        dprintk("NFS: MNT request succeeded\n");
        status = 0;

        /*
         * If the server didn't provide a flavor list, allow the
         * client to try any flavor.
         */
        if (info->version != NFS_MNT3_VERSION || *info->auth_flav_len == 0) {
                dprintk("NFS: Faking up auth_flavs list\n");
                info->auth_flavs[0] = RPC_AUTH_NULL;
                *info->auth_flav_len = 1;
        }
out:
        return status;

out_clnt_err:
        status = PTR_ERR(mnt_clnt);
        dprintk("NFS: failed to create MNT RPC client, status=%d\n", status);
        goto out;

out_call_err:
        dprintk("NFS: MNT request failed, status=%d\n", status);
        goto out;

out_mnt_err:
        dprintk("NFS: MNT server returned result %d\n", result.errno);
        status = result.errno;
        goto out;
}

/*
 * XDR encode/decode functions for MOUNT
 */

static void encode_mntdirpath(struct xdr_stream *xdr, const char *pathname)
{
        const u32 pathname_len = strlen(pathname);
        __be32 *p;

        p = xdr_reserve_space(xdr, 4 + pathname_len);
        xdr_encode_opaque(p, pathname, pathname_len);
}

static void mnt_xdr_enc_dirpath(struct rpc_rqst *req, struct xdr_stream *xdr,
                                const void *dirpath)
{
        encode_mntdirpath(xdr, dirpath);
}

/*
 * RFC 1094: "A non-zero status indicates some sort of error.  In this
 * case, the status is a UNIX error number."  This can be problematic
 * if the server and client use different errno values for the same
 * error.
 *
 * However, the OpenGroup XNFS spec provides a simple mapping that is
 * independent of local errno values on the server and the client.
 */
static int decode_status(struct xdr_stream *xdr, struct mountres *res)
{
        unsigned int i;
        u32 status;
        __be32 *p;

        p = xdr_inline_decode(xdr, 4);
        if (unlikely(p == NULL))
                return -EIO;
        status = be32_to_cpup(p);

        for (i = 0; i < ARRAY_SIZE(mnt_errtbl); i++) {
                if (mnt_errtbl[i].status == status) {
                        res->errno = mnt_errtbl[i].errno;
                        return 0;
                }
        }

        dprintk("NFS: unrecognized MNT status code: %u\n", status);
        res->errno = -EACCES;
        return 0;
}

static int decode_fhandle(struct xdr_stream *xdr, struct mountres *res)
{
        struct nfs_fh *fh = res->fh;
        __be32 *p;

        p = xdr_inline_decode(xdr, NFS2_FHSIZE);
        if (unlikely(p == NULL))
                return -EIO;

        fh->size = NFS2_FHSIZE;
        memcpy(fh->data, p, NFS2_FHSIZE);
        return 0;
}

static int mnt_xdr_dec_mountres(struct rpc_rqst *req,
                                struct xdr_stream *xdr,
                                void *data)
{
        struct mountres *res = data;
        int status;

        status = decode_status(xdr, res);
        if (unlikely(status != 0 || res->errno != 0))
                return status;
        return decode_fhandle(xdr, res);
}

static int decode_fhs_status(struct xdr_stream *xdr, struct mountres *res)
{
        unsigned int i;
        u32 status;
        __be32 *p;

        p = xdr_inline_decode(xdr, 4);
        if (unlikely(p == NULL))
                return -EIO;
        status = be32_to_cpup(p);

        for (i = 0; i < ARRAY_SIZE(mnt3_errtbl); i++) {
                if (mnt3_errtbl[i].status == status) {
                        res->errno = mnt3_errtbl[i].errno;
                        return 0;
                }
        }

        dprintk("NFS: unrecognized MNT3 status code: %u\n", status);
        res->errno = -EACCES;
        return 0;
}

static int decode_fhandle3(struct xdr_stream *xdr, struct mountres *res)
{
        struct nfs_fh *fh = res->fh;
        u32 size;
        __be32 *p;

        p = xdr_inline_decode(xdr, 4);
        if (unlikely(p == NULL))
                return -EIO;

        size = be32_to_cpup(p);
        if (size > NFS3_FHSIZE || size == 0)
                return -EIO;

        p = xdr_inline_decode(xdr, size);
        if (unlikely(p == NULL))
                return -EIO;

        fh->size = size;
        memcpy(fh->data, p, size);
        return 0;
}

static int decode_auth_flavors(struct xdr_stream *xdr, struct mountres *res)
{
        rpc_authflavor_t *flavors = res->auth_flavors;
        unsigned int *count = res->auth_count;
        u32 entries, i;
        __be32 *p;

        if (*count == 0)
                return 0;

        p = xdr_inline_decode(xdr, 4);
        if (unlikely(p == NULL))
                return -EIO;
        entries = be32_to_cpup(p);
        dprintk("NFS: received %u auth flavors\n", entries);
        if (entries > NFS_MAX_SECFLAVORS)
                entries = NFS_MAX_SECFLAVORS;

        p = xdr_inline_decode(xdr, 4 * entries);
        if (unlikely(p == NULL))
                return -EIO;

        if (entries > *count)
                entries = *count;

        for (i = 0; i < entries; i++) {
                flavors[i] = be32_to_cpup(p++);
                dprintk("NFS:   auth flavor[%u]: %d\n", i, flavors[i]);
        }
        *count = i;

        return 0;
}

static int mnt_xdr_dec_mountres3(struct rpc_rqst *req,
                                 struct xdr_stream *xdr,
                                 void *data)
{
        struct mountres *res = data;
        int status;

        status = decode_fhs_status(xdr, res);
        if (unlikely(status != 0 || res->errno != 0))
                return status;
        status = decode_fhandle3(xdr, res);
        if (unlikely(status != 0)) {
                res->errno = -EBADHANDLE;
                return 0;
        }
        return decode_auth_flavors(xdr, res);
}

static const struct rpc_procinfo mnt_procedures[] = {
        [MOUNTPROC_MNT] = {
                .p_proc         = MOUNTPROC_MNT,
                .p_encode       = mnt_xdr_enc_dirpath,
                .p_decode       = mnt_xdr_dec_mountres,
                .p_arglen       = MNT_enc_dirpath_sz,
                .p_replen       = MNT_dec_mountres_sz,
                .p_statidx      = MOUNTPROC_MNT,
                .p_name         = "MOUNT",
        },
        [MOUNTPROC_UMNT] = {
                .p_proc         = MOUNTPROC_UMNT,
                .p_encode       = mnt_xdr_enc_dirpath,
                .p_arglen       = MNT_enc_dirpath_sz,
                .p_statidx      = MOUNTPROC_UMNT,
                .p_name         = "UMOUNT",
        },
};

static const struct rpc_procinfo mnt3_procedures[] = {
        [MOUNTPROC3_MNT] = {
                .p_proc         = MOUNTPROC3_MNT,
                .p_encode       = mnt_xdr_enc_dirpath,
                .p_decode       = mnt_xdr_dec_mountres3,
                .p_arglen       = MNT_enc_dirpath_sz,
                .p_replen       = MNT_dec_mountres3_sz,
                .p_statidx      = MOUNTPROC3_MNT,
                .p_name         = "MOUNT",
        },
        [MOUNTPROC3_UMNT] = {
                .p_proc         = MOUNTPROC3_UMNT,
                .p_encode       = mnt_xdr_enc_dirpath,
                .p_arglen       = MNT_enc_dirpath_sz,
                .p_statidx      = MOUNTPROC3_UMNT,
                .p_name         = "UMOUNT",
        },
};

static unsigned int mnt_counts[ARRAY_SIZE(mnt_procedures)];
static const struct rpc_version mnt_version1 = {
        .number         = 1,
        .nrprocs        = ARRAY_SIZE(mnt_procedures),
        .procs          = mnt_procedures,
        .counts         = mnt_counts,
};

static unsigned int mnt3_counts[ARRAY_SIZE(mnt3_procedures)];
static const struct rpc_version mnt_version3 = {
        .number         = 3,
        .nrprocs        = ARRAY_SIZE(mnt3_procedures),
        .procs          = mnt3_procedures,
        .counts         = mnt3_counts,
};

static const struct rpc_version *mnt_version[] = {
        NULL,
        &mnt_version1,
        NULL,
        &mnt_version3,
};

static struct rpc_stat mnt_stats;

static const struct rpc_program mnt_program = {
        .name           = "mount",
        .number         = NFS_MNT_PROGRAM,
        .nrvers         = ARRAY_SIZE(mnt_version),
        .version        = mnt_version,
        .stats          = &mnt_stats,
};