idmap.c

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/*
 * fs/nfs/idmap.c
 *
 *  UID and GID to name mapping for clients.
 *
 *  Copyright (c) 2002 The Regents of the University of Michigan.
 *  All rights reserved.
 *
 *  Marius Aamodt Eriksen <[email protected]>
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *  3. Neither the name of the University nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
 *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 *  DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 *  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 *  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 *  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 *  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 *  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
#include <linux/types.h>
#include <linux/parser.h>
#include <linux/fs.h>
#include <linux/nfs_idmap.h>
#include <net/net_namespace.h>
#include <linux/sunrpc/rpc_pipe_fs.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_fs_sb.h>
#include <linux/key.h>
#include <linux/keyctl.h>
#include <linux/key-type.h>
#include <keys/user-type.h>
#include <linux/module.h>

#include "internal.h"
#include "netns.h"

#define NFS_UINT_MAXLEN 11

static const struct cred *id_resolver_cache;
static struct key_type key_type_id_resolver_legacy;

struct idmap_legacy_upcalldata {
    struct rpc_pipe_msg pipe_msg;
    struct idmap_msg idmap_msg;
    struct key_construction *key_cons;
    struct idmap *idmap;
};

struct idmap {
    struct rpc_pipe     *idmap_pipe;
    struct idmap_legacy_upcalldata *idmap_upcall_data;
    struct mutex        idmap_mutex;
};

void nfs_fattr_init_names(struct nfs_fattr *fattr,
        struct nfs4_string *owner_name,
        struct nfs4_string *group_name)
{
    fattr->owner_name = owner_name;
    fattr->group_name = group_name;
}

static void nfs_fattr_free_owner_name(struct nfs_fattr *fattr)
{
    fattr->valid &= ~NFS_ATTR_FATTR_OWNER_NAME;
    kfree(fattr->owner_name->data);
}

static void nfs_fattr_free_group_name(struct nfs_fattr *fattr)
{
    fattr->valid &= ~NFS_ATTR_FATTR_GROUP_NAME;
    kfree(fattr->group_name->data);
}

static bool nfs_fattr_map_owner_name(struct nfs_server *server, struct nfs_fattr *fattr)
{
    struct nfs4_string *owner = fattr->owner_name;
    __u32 uid;

    if (!(fattr->valid & NFS_ATTR_FATTR_OWNER_NAME))
        return false;
    if (nfs_map_name_to_uid(server, owner->data, owner->len, &uid) == 0) {
        fattr->uid = uid;
        fattr->valid |= NFS_ATTR_FATTR_OWNER;
    }
    return true;
}

static bool nfs_fattr_map_group_name(struct nfs_server *server, struct nfs_fattr *fattr)
{
    struct nfs4_string *group = fattr->group_name;
    __u32 gid;

    if (!(fattr->valid & NFS_ATTR_FATTR_GROUP_NAME))
        return false;
    if (nfs_map_group_to_gid(server, group->data, group->len, &gid) == 0) {
        fattr->gid = gid;
        fattr->valid |= NFS_ATTR_FATTR_GROUP;
    }
    return true;
}

void nfs_fattr_free_names(struct nfs_fattr *fattr)
{
    if (fattr->valid & NFS_ATTR_FATTR_OWNER_NAME)
        nfs_fattr_free_owner_name(fattr);
    if (fattr->valid & NFS_ATTR_FATTR_GROUP_NAME)
        nfs_fattr_free_group_name(fattr);
}

void nfs_fattr_map_and_free_names(struct nfs_server *server, struct nfs_fattr *fattr)
{
    if (nfs_fattr_map_owner_name(server, fattr))
        nfs_fattr_free_owner_name(fattr);
    if (nfs_fattr_map_group_name(server, fattr))
        nfs_fattr_free_group_name(fattr);
}

static int nfs_map_string_to_numeric(const char *name, size_t namelen, __u32 *res)
{
    unsigned long val;
    char buf[16];

    if (memchr(name, '@', namelen) != NULL || namelen >= sizeof(buf))
        return 0;
    memcpy(buf, name, namelen);
    buf[namelen] = '\0';
    if (kstrtoul(buf, 0, &val) != 0)
        return 0;
    *res = val;
    return 1;
}

static int nfs_map_numeric_to_string(__u32 id, char *buf, size_t buflen)
{
    return snprintf(buf, buflen, "%u", id);
}

static struct key_type key_type_id_resolver = {
    .name       = "id_resolver",
    .instantiate    = user_instantiate,
    .match      = user_match,
    .revoke     = user_revoke,
    .destroy    = user_destroy,
    .describe   = user_describe,
    .read       = user_read,
};

static int nfs_idmap_init_keyring(void)
{
    struct cred *cred;
    struct key *keyring;
    int ret = 0;

    printk(KERN_NOTICE "NFS: Registering the %s key type\n",
        key_type_id_resolver.name);

    cred = prepare_kernel_cred(NULL);
    if (!cred)
        return -ENOMEM;

    keyring = key_alloc(&key_type_keyring, ".id_resolver", 0, 0, cred,
                 (KEY_POS_ALL & ~KEY_POS_SETATTR) |
                 KEY_USR_VIEW | KEY_USR_READ,
                 KEY_ALLOC_NOT_IN_QUOTA);
    if (IS_ERR(keyring)) {
        ret = PTR_ERR(keyring);
        goto failed_put_cred;
    }

    ret = key_instantiate_and_link(keyring, NULL, 0, NULL, NULL);
    if (ret < 0)
        goto failed_put_key;

    ret = register_key_type(&key_type_id_resolver);
    if (ret < 0)
        goto failed_put_key;

    ret = register_key_type(&key_type_id_resolver_legacy);
    if (ret < 0)
        goto failed_reg_legacy;

    set_bit(KEY_FLAG_ROOT_CAN_CLEAR, &keyring->flags);
    cred->thread_keyring = keyring;
    cred->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING;
    id_resolver_cache = cred;
    return 0;

failed_reg_legacy:
    unregister_key_type(&key_type_id_resolver);
failed_put_key:
    key_put(keyring);
failed_put_cred:
    put_cred(cred);
    return ret;
}

static void nfs_idmap_quit_keyring(void)
{
    key_revoke(id_resolver_cache->thread_keyring);
    unregister_key_type(&key_type_id_resolver);
    unregister_key_type(&key_type_id_resolver_legacy);
    put_cred(id_resolver_cache);
}

/*
 * Assemble the description to pass to request_key()
 * This function will allocate a new string and update dest to point
 * at it.  The caller is responsible for freeing dest.
 *
 * On error 0 is returned.  Otherwise, the length of dest is returned.
 */
static ssize_t nfs_idmap_get_desc(const char *name, size_t namelen,
                const char *type, size_t typelen, char **desc)
{
    char *cp;
    size_t desclen = typelen + namelen + 2;

    *desc = kmalloc(desclen, GFP_KERNEL);
    if (!*desc)
        return -ENOMEM;

    cp = *desc;
    memcpy(cp, type, typelen);
    cp += typelen;
    *cp++ = ':';

    memcpy(cp, name, namelen);
    cp += namelen;
    *cp = '\0';
    return desclen;
}

static ssize_t nfs_idmap_request_key(struct key_type *key_type,
                     const char *name, size_t namelen,
                     const char *type, void *data,
                     size_t data_size, struct idmap *idmap)
{
    const struct cred *saved_cred;
    struct key *rkey;
    char *desc;
    struct user_key_payload *payload;
    ssize_t ret;

    ret = nfs_idmap_get_desc(name, namelen, type, strlen(type), &desc);
    if (ret <= 0)
        goto out;

    saved_cred = override_creds(id_resolver_cache);
    if (idmap)
        rkey = request_key_with_auxdata(key_type, desc, "", 0, idmap);
    else
        rkey = request_key(&key_type_id_resolver, desc, "");
    revert_creds(saved_cred);

    kfree(desc);
    if (IS_ERR(rkey)) {
        ret = PTR_ERR(rkey);
        goto out;
    }

    rcu_read_lock();
    rkey->perm |= KEY_USR_VIEW;

    ret = key_validate(rkey);
    if (ret < 0)
        goto out_up;

    payload = rcu_dereference(rkey->payload.data);
    if (IS_ERR_OR_NULL(payload)) {
        ret = PTR_ERR(payload);
        goto out_up;
    }

    ret = payload->datalen;
    if (ret > 0 && ret <= data_size)
        memcpy(data, payload->data, ret);
    else
        ret = -EINVAL;

out_up:
    rcu_read_unlock();
    key_put(rkey);
out:
    return ret;
}

static ssize_t nfs_idmap_get_key(const char *name, size_t namelen,
                 const char *type, void *data,
                 size_t data_size, struct idmap *idmap)
{
    ssize_t ret = nfs_idmap_request_key(&key_type_id_resolver,
                        name, namelen, type, data,
                        data_size, NULL);
    if (ret < 0) {
        mutex_lock(&idmap->idmap_mutex);
        ret = nfs_idmap_request_key(&key_type_id_resolver_legacy,
                        name, namelen, type, data,
                        data_size, idmap);
        mutex_unlock(&idmap->idmap_mutex);
    }
    return ret;
}

/* ID -> Name */
static ssize_t nfs_idmap_lookup_name(__u32 id, const char *type, char *buf,
                     size_t buflen, struct idmap *idmap)
{
    char id_str[NFS_UINT_MAXLEN];
    int id_len;
    ssize_t ret;

    id_len = snprintf(id_str, sizeof(id_str), "%u", id);
    ret = nfs_idmap_get_key(id_str, id_len, type, buf, buflen, idmap);
    if (ret < 0)
        return -EINVAL;
    return ret;
}

/* Name -> ID */
static int nfs_idmap_lookup_id(const char *name, size_t namelen, const char *type,
                   __u32 *id, struct idmap *idmap)
{
    char id_str[NFS_UINT_MAXLEN];
    long id_long;
    ssize_t data_size;
    int ret = 0;

    data_size = nfs_idmap_get_key(name, namelen, type, id_str, NFS_UINT_MAXLEN, idmap);
    if (data_size <= 0) {
        ret = -EINVAL;
    } else {
        ret = kstrtol(id_str, 10, &id_long);
        *id = (__u32)id_long;
    }
    return ret;
}

/* idmap classic begins here */

enum {
    Opt_find_uid, Opt_find_gid, Opt_find_user, Opt_find_group, Opt_find_err
};

static const match_table_t nfs_idmap_tokens = {
    { Opt_find_uid, "uid:%s" },
    { Opt_find_gid, "gid:%s" },
    { Opt_find_user, "user:%s" },
    { Opt_find_group, "group:%s" },
    { Opt_find_err, NULL }
};

static int nfs_idmap_legacy_upcall(struct key_construction *, const char *, void *);
static ssize_t idmap_pipe_downcall(struct file *, const char __user *,
                   size_t);
static void idmap_release_pipe(struct inode *);
static void idmap_pipe_destroy_msg(struct rpc_pipe_msg *);

static const struct rpc_pipe_ops idmap_upcall_ops = {
    .upcall     = rpc_pipe_generic_upcall,
    .downcall   = idmap_pipe_downcall,
    .release_pipe   = idmap_release_pipe,
    .destroy_msg    = idmap_pipe_destroy_msg,
};

static struct key_type key_type_id_resolver_legacy = {
    .name       = "id_legacy",
    .instantiate    = user_instantiate,
    .match      = user_match,
    .revoke     = user_revoke,
    .destroy    = user_destroy,
    .describe   = user_describe,
    .read       = user_read,
    .request_key    = nfs_idmap_legacy_upcall,
};

static void __nfs_idmap_unregister(struct rpc_pipe *pipe)
{
    if (pipe->dentry)
        rpc_unlink(pipe->dentry);
}

static int __nfs_idmap_register(struct dentry *dir,
                     struct idmap *idmap,
                     struct rpc_pipe *pipe)
{
    struct dentry *dentry;

    dentry = rpc_mkpipe_dentry(dir, "idmap", idmap, pipe);
    if (IS_ERR(dentry))
        return PTR_ERR(dentry);
    pipe->dentry = dentry;
    return 0;
}

static void nfs_idmap_unregister(struct nfs_client *clp,
                      struct rpc_pipe *pipe)
{
    struct net *net = clp->cl_net;
    struct super_block *pipefs_sb;

    pipefs_sb = rpc_get_sb_net(net);
    if (pipefs_sb) {
        __nfs_idmap_unregister(pipe);
        rpc_put_sb_net(net);
    }
}

static int nfs_idmap_register(struct nfs_client *clp,
                   struct idmap *idmap,
                   struct rpc_pipe *pipe)
{
    struct net *net = clp->cl_net;
    struct super_block *pipefs_sb;
    int err = 0;

    pipefs_sb = rpc_get_sb_net(net);
    if (pipefs_sb) {
        if (clp->cl_rpcclient->cl_dentry)
            err = __nfs_idmap_register(clp->cl_rpcclient->cl_dentry,
                           idmap, pipe);
        rpc_put_sb_net(net);
    }
    return err;
}

int
nfs_idmap_new(struct nfs_client *clp)
{
    struct idmap *idmap;
    struct rpc_pipe *pipe;
    int error;

    idmap = kzalloc(sizeof(*idmap), GFP_KERNEL);
    if (idmap == NULL)
        return -ENOMEM;

    pipe = rpc_mkpipe_data(&idmap_upcall_ops, 0);
    if (IS_ERR(pipe)) {
        error = PTR_ERR(pipe);
        kfree(idmap);
        return error;
    }
    error = nfs_idmap_register(clp, idmap, pipe);
    if (error) {
        rpc_destroy_pipe_data(pipe);
        kfree(idmap);
        return error;
    }
    idmap->idmap_pipe = pipe;
    mutex_init(&idmap->idmap_mutex);

    clp->cl_idmap = idmap;
    return 0;
}

void
nfs_idmap_delete(struct nfs_client *clp)
{
    struct idmap *idmap = clp->cl_idmap;

    if (!idmap)
        return;
    nfs_idmap_unregister(clp, idmap->idmap_pipe);
    rpc_destroy_pipe_data(idmap->idmap_pipe);
    clp->cl_idmap = NULL;
    kfree(idmap);
}

static int __rpc_pipefs_event(struct nfs_client *clp, unsigned long event,
                  struct super_block *sb)
{
    int err = 0;

    switch (event) {
    case RPC_PIPEFS_MOUNT:
        err = __nfs_idmap_register(clp->cl_rpcclient->cl_dentry,
                        clp->cl_idmap,
                        clp->cl_idmap->idmap_pipe);
        break;
    case RPC_PIPEFS_UMOUNT:
        if (clp->cl_idmap->idmap_pipe) {
            struct dentry *parent;

            parent = clp->cl_idmap->idmap_pipe->dentry->d_parent;
            __nfs_idmap_unregister(clp->cl_idmap->idmap_pipe);
            /*
             * Note: This is a dirty hack. SUNRPC hook has been
             * called already but simple_rmdir() call for the
             * directory returned with error because of idmap pipe
             * inside. Thus now we have to remove this directory
             * here.
             */
            if (rpc_rmdir(parent))
                printk(KERN_ERR "NFS: %s: failed to remove "
                    "clnt dir!\n", __func__);
        }
        break;
    default:
        printk(KERN_ERR "NFS: %s: unknown event: %ld\n", __func__,
            event);
        return -ENOTSUPP;
    }
    return err;
}

static struct nfs_client *nfs_get_client_for_event(struct net *net, int event)
{
    struct nfs_net *nn = net_generic(net, nfs_net_id);
    struct dentry *cl_dentry;
    struct nfs_client *clp;
    int err;

restart:
    spin_lock(&nn->nfs_client_lock);
    list_for_each_entry(clp, &nn->nfs_client_list, cl_share_link) {
        /* Wait for initialisation to finish */
        if (clp->cl_cons_state == NFS_CS_INITING) {
            atomic_inc(&clp->cl_count);
            spin_unlock(&nn->nfs_client_lock);
            err = nfs_wait_client_init_complete(clp);
            nfs_put_client(clp);
            if (err)
                return NULL;
            goto restart;
        }
        /* Skip nfs_clients that failed to initialise */
        if (clp->cl_cons_state < 0)
            continue;
        smp_rmb();
        if (clp->rpc_ops != &nfs_v4_clientops)
            continue;
        cl_dentry = clp->cl_idmap->idmap_pipe->dentry;
        if (((event == RPC_PIPEFS_MOUNT) && cl_dentry) ||
            ((event == RPC_PIPEFS_UMOUNT) && !cl_dentry))
            continue;
        atomic_inc(&clp->cl_count);
        spin_unlock(&nn->nfs_client_lock);
        return clp;
    }
    spin_unlock(&nn->nfs_client_lock);
    return NULL;
}

static int rpc_pipefs_event(struct notifier_block *nb, unsigned long event,
                void *ptr)
{
    struct super_block *sb = ptr;
    struct nfs_client *clp;
    int error = 0;

    if (!try_module_get(THIS_MODULE))
        return 0;

    while ((clp = nfs_get_client_for_event(sb->s_fs_info, event))) {
        error = __rpc_pipefs_event(clp, event, sb);
        nfs_put_client(clp);
        if (error)
            break;
    }
    module_put(THIS_MODULE);
    return error;
}

#define PIPEFS_NFS_PRIO     1

static struct notifier_block nfs_idmap_block = {
    .notifier_call  = rpc_pipefs_event,
    .priority   = SUNRPC_PIPEFS_NFS_PRIO,
};

int nfs_idmap_init(void)
{
    int ret;
    ret = nfs_idmap_init_keyring();
    if (ret != 0)
        goto out;
    ret = rpc_pipefs_notifier_register(&nfs_idmap_block);
    if (ret != 0)
        nfs_idmap_quit_keyring();
out:
    return ret;
}

void nfs_idmap_quit(void)
{
    rpc_pipefs_notifier_unregister(&nfs_idmap_block);
    nfs_idmap_quit_keyring();
}

static int nfs_idmap_prepare_message(char *desc, struct idmap *idmap,
                     struct idmap_msg *im,
                     struct rpc_pipe_msg *msg)
{
    substring_t substr;
    int token, ret;

    im->im_type = IDMAP_TYPE_GROUP;
    token = match_token(desc, nfs_idmap_tokens, &substr);

    switch (token) {
    case Opt_find_uid:
        im->im_type = IDMAP_TYPE_USER;
    case Opt_find_gid:
        im->im_conv = IDMAP_CONV_NAMETOID;
        ret = match_strlcpy(im->im_name, &substr, IDMAP_NAMESZ);
        break;

    case Opt_find_user:
        im->im_type = IDMAP_TYPE_USER;
    case Opt_find_group:
        im->im_conv = IDMAP_CONV_IDTONAME;
        ret = match_int(&substr, &im->im_id);
        break;

    default:
        ret = -EINVAL;
        goto out;
    }

    msg->data = im;
    msg->len  = sizeof(struct idmap_msg);

out:
    return ret;
}

static bool
nfs_idmap_prepare_pipe_upcall(struct idmap *idmap,
        struct idmap_legacy_upcalldata *data)
{
    if (idmap->idmap_upcall_data != NULL) {
        WARN_ON_ONCE(1);
        return false;
    }
    idmap->idmap_upcall_data = data;
    return true;
}

static void
nfs_idmap_complete_pipe_upcall_locked(struct idmap *idmap, int ret)
{
    struct key_construction *cons = idmap->idmap_upcall_data->key_cons;

    kfree(idmap->idmap_upcall_data);
    idmap->idmap_upcall_data = NULL;
    complete_request_key(cons, ret);
}

static void
nfs_idmap_abort_pipe_upcall(struct idmap *idmap, int ret)
{
    if (idmap->idmap_upcall_data != NULL)
        nfs_idmap_complete_pipe_upcall_locked(idmap, ret);
}

static int nfs_idmap_legacy_upcall(struct key_construction *cons,
                   const char *op,
                   void *aux)
{
    struct idmap_legacy_upcalldata *data;
    struct rpc_pipe_msg *msg;
    struct idmap_msg *im;
    struct idmap *idmap = (struct idmap *)aux;
    struct key *key = cons->key;
    int ret = -ENOMEM;

    /* msg and im are freed in idmap_pipe_destroy_msg */
    data = kzalloc(sizeof(*data), GFP_KERNEL);
    if (!data)
        goto out1;

    msg = &data->pipe_msg;
    im = &data->idmap_msg;
    data->idmap = idmap;
    data->key_cons = cons;

    ret = nfs_idmap_prepare_message(key->description, idmap, im, msg);
    if (ret < 0)
        goto out2;

    ret = -EAGAIN;
    if (!nfs_idmap_prepare_pipe_upcall(idmap, data))
        goto out2;

    ret = rpc_queue_upcall(idmap->idmap_pipe, msg);
    if (ret < 0)
        nfs_idmap_abort_pipe_upcall(idmap, ret);

    return ret;
out2:
    kfree(data);
out1:
    complete_request_key(cons, ret);
    return ret;
}

static int nfs_idmap_instantiate(struct key *key, struct key *authkey, char *data)
{
    return key_instantiate_and_link(key, data, strlen(data) + 1,
                    id_resolver_cache->thread_keyring,
                    authkey);
}

static int nfs_idmap_read_and_verify_message(struct idmap_msg *im,
        struct idmap_msg *upcall,
        struct key *key, struct key *authkey)
{
    char id_str[NFS_UINT_MAXLEN];
    int ret = -ENOKEY;

    /* ret = -ENOKEY */
    if (upcall->im_type != im->im_type || upcall->im_conv != im->im_conv)
        goto out;
    switch (im->im_conv) {
    case IDMAP_CONV_NAMETOID:
        if (strcmp(upcall->im_name, im->im_name) != 0)
            break;
        sprintf(id_str, "%d", im->im_id);
        ret = nfs_idmap_instantiate(key, authkey, id_str);
        break;
    case IDMAP_CONV_IDTONAME:
        if (upcall->im_id != im->im_id)
            break;
        ret = nfs_idmap_instantiate(key, authkey, im->im_name);
        break;
    default:
        ret = -EINVAL;
    }
out:
    return ret;
}

static ssize_t
idmap_pipe_downcall(struct file *filp, const char __user *src, size_t mlen)
{
    struct rpc_inode *rpci = RPC_I(filp->f_path.dentry->d_inode);
    struct idmap *idmap = (struct idmap *)rpci->private;
    struct key_construction *cons;
    struct idmap_msg im;
    size_t namelen_in;
    int ret = -ENOKEY;

    /* If instantiation is successful, anyone waiting for key construction
     * will have been woken up and someone else may now have used
     * idmap_key_cons - so after this point we may no longer touch it.
     */
    if (idmap->idmap_upcall_data == NULL)
        goto out_noupcall;

    cons = idmap->idmap_upcall_data->key_cons;

    if (mlen != sizeof(im)) {
        ret = -ENOSPC;
        goto out;
    }

    if (copy_from_user(&im, src, mlen) != 0) {
        ret = -EFAULT;
        goto out;
    }

    if (!(im.im_status & IDMAP_STATUS_SUCCESS)) {
        ret = -ENOKEY;
        goto out;
    }

    namelen_in = strnlen(im.im_name, IDMAP_NAMESZ);
    if (namelen_in == 0 || namelen_in == IDMAP_NAMESZ) {
        ret = -EINVAL;
        goto out;
}

    ret = nfs_idmap_read_and_verify_message(&im,
            &idmap->idmap_upcall_data->idmap_msg,
            cons->key, cons->authkey);
    if (ret >= 0) {
        key_set_timeout(cons->key, nfs_idmap_cache_timeout);
        ret = mlen;
    }

out:
    nfs_idmap_complete_pipe_upcall_locked(idmap, ret);
out_noupcall:
    return ret;
}

static void
idmap_pipe_destroy_msg(struct rpc_pipe_msg *msg)
{
    struct idmap_legacy_upcalldata *data = container_of(msg,
            struct idmap_legacy_upcalldata,
            pipe_msg);
    struct idmap *idmap = data->idmap;

    if (msg->errno)
        nfs_idmap_abort_pipe_upcall(idmap, msg->errno);
}

static void
idmap_release_pipe(struct inode *inode)
{
    struct rpc_inode *rpci = RPC_I(inode);
    struct idmap *idmap = (struct idmap *)rpci->private;

    nfs_idmap_abort_pipe_upcall(idmap, -EPIPE);
}

int nfs_map_name_to_uid(const struct nfs_server *server, const char *name, size_t namelen, __u32 *uid)
{
    struct idmap *idmap = server->nfs_client->cl_idmap;

    if (nfs_map_string_to_numeric(name, namelen, uid))
        return 0;
    return nfs_idmap_lookup_id(name, namelen, "uid", uid, idmap);
}

int nfs_map_group_to_gid(const struct nfs_server *server, const char *name, size_t namelen, __u32 *gid)
{
    struct idmap *idmap = server->nfs_client->cl_idmap;

    if (nfs_map_string_to_numeric(name, namelen, gid))
        return 0;
    return nfs_idmap_lookup_id(name, namelen, "gid", gid, idmap);
}

int nfs_map_uid_to_name(const struct nfs_server *server, __u32 uid, char *buf, size_t buflen)
{
    struct idmap *idmap = server->nfs_client->cl_idmap;
    int ret = -EINVAL;

    if (!(server->caps & NFS_CAP_UIDGID_NOMAP))
        ret = nfs_idmap_lookup_name(uid, "user", buf, buflen, idmap);
    if (ret < 0)
        ret = nfs_map_numeric_to_string(uid, buf, buflen);
    return ret;
}
int nfs_map_gid_to_group(const struct nfs_server *server, __u32 gid, char *buf, size_t buflen)
{
    struct idmap *idmap = server->nfs_client->cl_idmap;
    int ret = -EINVAL;

    if (!(server->caps & NFS_CAP_UIDGID_NOMAP))
        ret = nfs_idmap_lookup_name(gid, "group", buf, buflen, idmap);
    if (ret < 0)
        ret = nfs_map_numeric_to_string(gid, buf, buflen);
    return ret;
}