/*
 *  Mapping of UID/GIDs to name and vice versa.
 *
 *  Copyright (c) 2002, 2003 The Regents of the University of
 *  Michigan.  All rights reserved.
 *
 *  Marius Aamodt Eriksen <marius@umich.edu>
 *
 *  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/module.h>
#include <linux/seq_file.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/sunrpc/svc_xprt.h>
#include <net/net_namespace.h>
#include "idmap.h"
#include "nfsd.h"
#include "netns.h"
#include "vfs.h"

/*
 * Turn off idmapping when using AUTH_SYS.
 */
static bool nfs4_disable_idmapping = true;
module_param(nfs4_disable_idmapping, bool, 0644);
MODULE_PARM_DESC(nfs4_disable_idmapping,
                "Turn off server's NFSv4 idmapping when using 'sec=sys'");

/*
 * Cache entry
 */

/*
 * XXX we know that IDMAP_NAMESZ < PAGE_SIZE, but it's ugly to rely on
 * that.
 */

struct ent {
        struct cache_head h;
        int               type;                /* User / Group */
        u32               id;
        char              name[IDMAP_NAMESZ];
        char              authname[IDMAP_NAMESZ];
        struct rcu_head   rcu_head;
};

/* Common entry handling */

#define ENT_HASHBITS          8
#define ENT_HASHMAX           (1 << ENT_HASHBITS)

static void
ent_init(struct cache_head *cnew, struct cache_head *citm)
{
        struct ent *new = container_of(cnew, struct ent, h);
        struct ent *itm = container_of(citm, struct ent, h);

        new->id = itm->id;
        new->type = itm->type;

        strscpy(new->name, itm->name, sizeof(new->name));
        strscpy(new->authname, itm->authname, sizeof(new->authname));
}

static void
ent_put(struct kref *ref)
{
        struct ent *map = container_of(ref, struct ent, h.ref);
        kfree_rcu(map, rcu_head);
}

static struct cache_head *
ent_alloc(void)
{
        struct ent *e = kmalloc_obj(*e);
        if (e)
                return &e->h;
        else
                return NULL;
}

/*
 * ID -> Name cache
 */

static uint32_t
idtoname_hash(struct ent *ent)
{
        uint32_t hash;

        hash = hash_str(ent->authname, ENT_HASHBITS);
        hash = hash_long(hash ^ ent->id, ENT_HASHBITS);

        /* Flip LSB for user/group */
        if (ent->type == IDMAP_TYPE_GROUP)
                hash ^= 1;

        return hash;
}

static int
idtoname_upcall(struct cache_detail *cd, struct cache_head *h)
{
        return sunrpc_cache_pipe_upcall_timeout(cd, h);
}

static void
idtoname_request(struct cache_detail *cd, struct cache_head *ch, char **bpp,
    int *blen)
{
        struct ent *ent = container_of(ch, struct ent, h);
        char idstr[11];

        qword_add(bpp, blen, ent->authname);
        snprintf(idstr, sizeof(idstr), "%u", ent->id);
        qword_add(bpp, blen, ent->type == IDMAP_TYPE_GROUP ? "group" : "user");
        qword_add(bpp, blen, idstr);

        (*bpp)[-1] = '\n';
}

static int
idtoname_match(struct cache_head *ca, struct cache_head *cb)
{
        struct ent *a = container_of(ca, struct ent, h);
        struct ent *b = container_of(cb, struct ent, h);

        return (a->id == b->id && a->type == b->type &&
            strcmp(a->authname, b->authname) == 0);
}

static int
idtoname_show(struct seq_file *m, struct cache_detail *cd, struct cache_head *h)
{
        struct ent *ent;

        if (h == NULL) {
                seq_puts(m, "#domain type id [name]\n");
                return 0;
        }
        ent = container_of(h, struct ent, h);
        seq_printf(m, "%s %s %u", ent->authname,
                        ent->type == IDMAP_TYPE_GROUP ? "group" : "user",
                        ent->id);
        if (test_bit(CACHE_VALID, &h->flags))
                seq_printf(m, " %s", ent->name);
        seq_putc(m, '\n');
        return 0;
}

static void
warn_no_idmapd(struct cache_detail *detail, int has_died)
{
        printk("nfsd: nfsv4 idmapping failing: has idmapd %s?\n",
                        has_died ? "died" : "not been started");
}


static int         idtoname_parse(struct cache_detail *, char *, int);
static struct ent *idtoname_lookup(struct cache_detail *, struct ent *);
static struct ent *idtoname_update(struct cache_detail *, struct ent *,
                                   struct ent *);

static const struct cache_detail idtoname_cache_template = {
        .owner          = THIS_MODULE,
        .hash_size      = ENT_HASHMAX,
        .name           = "nfs4.idtoname",
        .cache_put      = ent_put,
        .cache_upcall   = idtoname_upcall,
        .cache_request  = idtoname_request,
        .cache_parse    = idtoname_parse,
        .cache_show     = idtoname_show,
        .warn_no_listener = warn_no_idmapd,
        .match          = idtoname_match,
        .init           = ent_init,
        .update         = ent_init,
        .alloc          = ent_alloc,
};

static int
idtoname_parse(struct cache_detail *cd, char *buf, int buflen)
{
        struct ent ent, *res;
        char *buf1, *bp;
        int len;
        int error = -EINVAL;

        if (buf[buflen - 1] != '\n')
                return (-EINVAL);
        buf[buflen - 1]= '\0';

        buf1 = kmalloc(PAGE_SIZE, GFP_KERNEL);
        if (buf1 == NULL)
                return (-ENOMEM);

        memset(&ent, 0, sizeof(ent));

        /* Authentication name */
        len = qword_get(&buf, buf1, PAGE_SIZE);
        if (len <= 0 || len >= IDMAP_NAMESZ)
                goto out;
        memcpy(ent.authname, buf1, sizeof(ent.authname));

        /* Type */
        if (qword_get(&buf, buf1, PAGE_SIZE) <= 0)
                goto out;
        ent.type = strcmp(buf1, "user") == 0 ?
                IDMAP_TYPE_USER : IDMAP_TYPE_GROUP;

        /* ID */
        if (qword_get(&buf, buf1, PAGE_SIZE) <= 0)
                goto out;
        ent.id = simple_strtoul(buf1, &bp, 10);
        if (bp == buf1)
                goto out;

        /* expiry */
        error = get_expiry(&buf, &ent.h.expiry_time);
        if (error)
                goto out;

        error = -ENOMEM;
        res = idtoname_lookup(cd, &ent);
        if (!res)
                goto out;

        /* Name */
        error = -EINVAL;
        len = qword_get(&buf, buf1, PAGE_SIZE);
        if (len < 0 || len >= IDMAP_NAMESZ)
                goto out;
        if (len == 0)
                set_bit(CACHE_NEGATIVE, &ent.h.flags);
        else
                memcpy(ent.name, buf1, sizeof(ent.name));
        error = -ENOMEM;
        res = idtoname_update(cd, &ent, res);
        if (res == NULL)
                goto out;

        cache_put(&res->h, cd);
        error = 0;
out:
        kfree(buf1);
        return error;
}

static struct ent *
idtoname_lookup(struct cache_detail *cd, struct ent *item)
{
        struct cache_head *ch = sunrpc_cache_lookup_rcu(cd, &item->h,
                                                        idtoname_hash(item));
        if (ch)
                return container_of(ch, struct ent, h);
        else
                return NULL;
}

static struct ent *
idtoname_update(struct cache_detail *cd, struct ent *new, struct ent *old)
{
        struct cache_head *ch = sunrpc_cache_update(cd, &new->h, &old->h,
                                                    idtoname_hash(new));
        if (ch)
                return container_of(ch, struct ent, h);
        else
                return NULL;
}


/*
 * Name -> ID cache
 */

static inline int
nametoid_hash(struct ent *ent)
{
        return hash_str(ent->name, ENT_HASHBITS);
}

static int
nametoid_upcall(struct cache_detail *cd, struct cache_head *h)
{
        return sunrpc_cache_pipe_upcall_timeout(cd, h);
}

static void
nametoid_request(struct cache_detail *cd, struct cache_head *ch, char **bpp,
    int *blen)
{
        struct ent *ent = container_of(ch, struct ent, h);

        qword_add(bpp, blen, ent->authname);
        qword_add(bpp, blen, ent->type == IDMAP_TYPE_GROUP ? "group" : "user");
        qword_add(bpp, blen, ent->name);

        (*bpp)[-1] = '\n';
}

static int
nametoid_match(struct cache_head *ca, struct cache_head *cb)
{
        struct ent *a = container_of(ca, struct ent, h);
        struct ent *b = container_of(cb, struct ent, h);

        return (a->type == b->type && strcmp(a->name, b->name) == 0 &&
            strcmp(a->authname, b->authname) == 0);
}

static int
nametoid_show(struct seq_file *m, struct cache_detail *cd, struct cache_head *h)
{
        struct ent *ent;

        if (h == NULL) {
                seq_puts(m, "#domain type name [id]\n");
                return 0;
        }
        ent = container_of(h, struct ent, h);
        seq_printf(m, "%s %s %s", ent->authname,
                        ent->type == IDMAP_TYPE_GROUP ? "group" : "user",
                        ent->name);
        if (test_bit(CACHE_VALID, &h->flags))
                seq_printf(m, " %u", ent->id);
        seq_putc(m, '\n');
        return 0;
}

static struct ent *nametoid_lookup(struct cache_detail *, struct ent *);
static struct ent *nametoid_update(struct cache_detail *, struct ent *,
                                   struct ent *);
static int         nametoid_parse(struct cache_detail *, char *, int);

static const struct cache_detail nametoid_cache_template = {
        .owner          = THIS_MODULE,
        .hash_size      = ENT_HASHMAX,
        .name           = "nfs4.nametoid",
        .cache_put      = ent_put,
        .cache_upcall   = nametoid_upcall,
        .cache_request  = nametoid_request,
        .cache_parse    = nametoid_parse,
        .cache_show     = nametoid_show,
        .warn_no_listener = warn_no_idmapd,
        .match          = nametoid_match,
        .init           = ent_init,
        .update         = ent_init,
        .alloc          = ent_alloc,
};

static int
nametoid_parse(struct cache_detail *cd, char *buf, int buflen)
{
        struct ent ent, *res;
        char *buf1;
        int len, error = -EINVAL;

        if (buf[buflen - 1] != '\n')
                return (-EINVAL);
        buf[buflen - 1]= '\0';

        buf1 = kmalloc(PAGE_SIZE, GFP_KERNEL);
        if (buf1 == NULL)
                return (-ENOMEM);

        memset(&ent, 0, sizeof(ent));

        /* Authentication name */
        len = qword_get(&buf, buf1, PAGE_SIZE);
        if (len <= 0 || len >= IDMAP_NAMESZ)
                goto out;
        memcpy(ent.authname, buf1, sizeof(ent.authname));

        /* Type */
        if (qword_get(&buf, buf1, PAGE_SIZE) <= 0)
                goto out;
        ent.type = strcmp(buf1, "user") == 0 ?
                IDMAP_TYPE_USER : IDMAP_TYPE_GROUP;

        /* Name */
        len = qword_get(&buf, buf1, PAGE_SIZE);
        if (len <= 0 || len >= IDMAP_NAMESZ)
                goto out;
        memcpy(ent.name, buf1, sizeof(ent.name));

        /* expiry */
        error = get_expiry(&buf, &ent.h.expiry_time);
        if (error)
                goto out;

        /* ID */
        error = get_int(&buf, &ent.id);
        if (error == -EINVAL)
                goto out;
        if (error == -ENOENT)
                set_bit(CACHE_NEGATIVE, &ent.h.flags);

        error = -ENOMEM;
        res = nametoid_lookup(cd, &ent);
        if (res == NULL)
                goto out;
        res = nametoid_update(cd, &ent, res);
        if (res == NULL)
                goto out;

        cache_put(&res->h, cd);
        error = 0;
out:
        kfree(buf1);
        return (error);
}


static struct ent *
nametoid_lookup(struct cache_detail *cd, struct ent *item)
{
        struct cache_head *ch = sunrpc_cache_lookup_rcu(cd, &item->h,
                                                        nametoid_hash(item));
        if (ch)
                return container_of(ch, struct ent, h);
        else
                return NULL;
}

static struct ent *
nametoid_update(struct cache_detail *cd, struct ent *new, struct ent *old)
{
        struct cache_head *ch = sunrpc_cache_update(cd, &new->h, &old->h,
                                                    nametoid_hash(new));
        if (ch)
                return container_of(ch, struct ent, h);
        else
                return NULL;
}

/*
 * Exported API
 */

int
nfsd_idmap_init(struct net *net)
{
        int rv;
        struct nfsd_net *nn = net_generic(net, nfsd_net_id);

        nn->idtoname_cache = cache_create_net(&idtoname_cache_template, net);
        if (IS_ERR(nn->idtoname_cache))
                return PTR_ERR(nn->idtoname_cache);
        rv = cache_register_net(nn->idtoname_cache, net);
        if (rv)
                goto destroy_idtoname_cache;
        nn->nametoid_cache = cache_create_net(&nametoid_cache_template, net);
        if (IS_ERR(nn->nametoid_cache)) {
                rv = PTR_ERR(nn->nametoid_cache);
                goto unregister_idtoname_cache;
        }
        rv = cache_register_net(nn->nametoid_cache, net);
        if (rv)
                goto destroy_nametoid_cache;
        return 0;

destroy_nametoid_cache:
        cache_destroy_net(nn->nametoid_cache, net);
unregister_idtoname_cache:
        cache_unregister_net(nn->idtoname_cache, net);
destroy_idtoname_cache:
        cache_destroy_net(nn->idtoname_cache, net);
        return rv;
}

void
nfsd_idmap_shutdown(struct net *net)
{
        struct nfsd_net *nn = net_generic(net, nfsd_net_id);

        cache_unregister_net(nn->idtoname_cache, net);
        cache_unregister_net(nn->nametoid_cache, net);
        cache_destroy_net(nn->idtoname_cache, net);
        cache_destroy_net(nn->nametoid_cache, net);
}

static int
idmap_lookup(struct svc_rqst *rqstp,
                struct ent *(*lookup_fn)(struct cache_detail *, struct ent *),
                struct ent *key, struct cache_detail *detail, struct ent **item)
{
        int ret;

        *item = lookup_fn(detail, key);
        if (!*item)
                return -ENOMEM;
 retry:
        ret = cache_check(detail, &(*item)->h, &rqstp->rq_chandle);

        if (ret == -ETIMEDOUT) {
                struct ent *prev_item = *item;
                *item = lookup_fn(detail, key);
                if (*item != prev_item)
                        goto retry;
                cache_put(&(*item)->h, detail);
        }
        return ret;
}

static char *
rqst_authname(struct svc_rqst *rqstp)
{
        struct auth_domain *clp;

        clp = rqstp->rq_gssclient ? rqstp->rq_gssclient : rqstp->rq_client;
        return clp->name;
}

static __be32
idmap_name_to_id(struct svc_rqst *rqstp, int type, const char *name, u32 namelen,
                u32 *id)
{
        struct ent *item, key = {
                .type = type,
        };
        int ret;
        struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);

        if (namelen + 1 > sizeof(key.name))
                return nfserr_badowner;
        memcpy(key.name, name, namelen);
        key.name[namelen] = '\0';
        strscpy(key.authname, rqst_authname(rqstp), sizeof(key.authname));
        ret = idmap_lookup(rqstp, nametoid_lookup, &key, nn->nametoid_cache, &item);
        if (ret == -ENOENT)
                return nfserr_badowner;
        if (ret)
                return nfserrno(ret);
        *id = item->id;
        cache_put(&item->h, nn->nametoid_cache);
        return 0;
}

static __be32 encode_ascii_id(struct xdr_stream *xdr, u32 id)
{
        char buf[11];
        int len;
        __be32 *p;

        len = sprintf(buf, "%u", id);
        p = xdr_reserve_space(xdr, len + 4);
        if (!p)
                return nfserr_resource;
        p = xdr_encode_opaque(p, buf, len);
        return 0;
}

static __be32 idmap_id_to_name(struct xdr_stream *xdr,
                               struct svc_rqst *rqstp, int type, u32 id)
{
        struct ent *item, key = {
                .id = id,
                .type = type,
        };
        __be32 status = nfs_ok;
        __be32 *p;
        int ret;
        struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);

        strscpy(key.authname, rqst_authname(rqstp), sizeof(key.authname));
        ret = idmap_lookup(rqstp, idtoname_lookup, &key, nn->idtoname_cache, &item);
        if (ret == -ENOENT)
                return encode_ascii_id(xdr, id);
        if (ret)
                return nfserrno(ret);
        ret = strlen(item->name);
        WARN_ON_ONCE(ret > IDMAP_NAMESZ);

        p = xdr_reserve_space(xdr, ret + 4);
        if (unlikely(!p)) {
                status = nfserr_resource;
                goto out_put;
        }
        xdr_encode_opaque(p, item->name, ret);
out_put:
        cache_put(&item->h, nn->idtoname_cache);
        return status;
}

static bool
numeric_name_to_id(struct svc_rqst *rqstp, int type, const char *name, u32 namelen, u32 *id)
{
        int ret;
        char buf[11];

        if (namelen + 1 > sizeof(buf))
                /* too long to represent a 32-bit id: */
                return false;
        /* Just to make sure it's null-terminated: */
        memcpy(buf, name, namelen);
        buf[namelen] = '\0';
        ret = kstrtouint(buf, 10, id);
        return ret == 0;
}

static __be32
do_name_to_id(struct svc_rqst *rqstp, int type, const char *name, u32 namelen, u32 *id)
{
        if (nfs4_disable_idmapping && rqstp->rq_cred.cr_flavor < RPC_AUTH_GSS)
                if (numeric_name_to_id(rqstp, type, name, namelen, id))
                        return 0;
                /*
                 * otherwise, fall through and try idmapping, for
                 * backwards compatibility with clients sending names:
                 */
        return idmap_name_to_id(rqstp, type, name, namelen, id);
}

static __be32 encode_name_from_id(struct xdr_stream *xdr,
                                  struct svc_rqst *rqstp, int type, u32 id)
{
        if (nfs4_disable_idmapping && rqstp->rq_cred.cr_flavor < RPC_AUTH_GSS)
                return encode_ascii_id(xdr, id);
        return idmap_id_to_name(xdr, rqstp, type, id);
}

/**
 * nfsd_map_name_to_uid - Map user@domain to local UID
 * @rqstp: RPC execution context
 * @name: user@domain name to be mapped
 * @namelen: length of name, in bytes
 * @uid: OUT: mapped local UID value
 *
 * Returns nfs_ok on success or an NFSv4 status code on failure.
 */
__be32 nfsd_map_name_to_uid(struct svc_rqst *rqstp, const char *name,
                            size_t namelen, kuid_t *uid)
{
        __be32 status;
        u32 id = -1;

        /*
         * The idmap lookup below triggers an upcall that invokes
         * cache_check(). RQ_USEDEFERRAL must be clear to prevent
         * cache_check() from setting RQ_DROPME via svc_defer().
         * NFSv4 servers are not permitted to drop requests. Also
         * RQ_DROPME will force NFSv4.1 session slot processing to
         * be skipped.
         */
        WARN_ON_ONCE(test_bit(RQ_USEDEFERRAL, &rqstp->rq_flags));

        if (name == NULL || namelen == 0)
                return nfserr_inval;

        status = do_name_to_id(rqstp, IDMAP_TYPE_USER, name, namelen, &id);
        if (status)
                return status;
        *uid = make_kuid(nfsd_user_namespace(rqstp), id);
        if (!uid_valid(*uid))
                status = nfserr_badowner;
        return status;
}

/**
 * nfsd_map_name_to_gid - Map user@domain to local GID
 * @rqstp: RPC execution context
 * @name: user@domain name to be mapped
 * @namelen: length of name, in bytes
 * @gid: OUT: mapped local GID value
 *
 * Returns nfs_ok on success or an NFSv4 status code on failure.
 */
__be32 nfsd_map_name_to_gid(struct svc_rqst *rqstp, const char *name,
                            size_t namelen, kgid_t *gid)
{
        __be32 status;
        u32 id = -1;

        /*
         * The idmap lookup below triggers an upcall that invokes
         * cache_check(). RQ_USEDEFERRAL must be clear to prevent
         * cache_check() from setting RQ_DROPME via svc_defer().
         * NFSv4 servers are not permitted to drop requests. Also
         * RQ_DROPME will force NFSv4.1 session slot processing to
         * be skipped.
         */
        WARN_ON_ONCE(test_bit(RQ_USEDEFERRAL, &rqstp->rq_flags));

        if (name == NULL || namelen == 0)
                return nfserr_inval;

        status = do_name_to_id(rqstp, IDMAP_TYPE_GROUP, name, namelen, &id);
        if (status)
                return status;
        *gid = make_kgid(nfsd_user_namespace(rqstp), id);
        if (!gid_valid(*gid))
                status = nfserr_badowner;
        return status;
}

__be32 nfsd4_encode_user(struct xdr_stream *xdr, struct svc_rqst *rqstp,
                         kuid_t uid)
{
        u32 id = from_kuid_munged(nfsd_user_namespace(rqstp), uid);
        return encode_name_from_id(xdr, rqstp, IDMAP_TYPE_USER, id);
}

__be32 nfsd4_encode_group(struct xdr_stream *xdr, struct svc_rqst *rqstp,
                          kgid_t gid)
{
        u32 id = from_kgid_munged(nfsd_user_namespace(rqstp), gid);
        return encode_name_from_id(xdr, rqstp, IDMAP_TYPE_GROUP, id);
}