// SPDX-License-Identifier: GPL-2.0
/*
 * Neil Brown <neilb@cse.unsw.edu.au>
 * J. Bruce Fields <bfields@umich.edu>
 * Andy Adamson <andros@umich.edu>
 * Dug Song <dugsong@monkey.org>
 *
 * RPCSEC_GSS server authentication.
 * This implements RPCSEC_GSS as defined in rfc2203 (rpcsec_gss) and rfc2078
 * (gssapi)
 *
 * The RPCSEC_GSS involves three stages:
 *  1/ context creation
 *  2/ data exchange
 *  3/ context destruction
 *
 * Context creation is handled largely by upcalls to user-space.
 *  In particular, GSS_Accept_sec_context is handled by an upcall
 * Data exchange is handled entirely within the kernel
 *  In particular, GSS_GetMIC, GSS_VerifyMIC, GSS_Seal, GSS_Unseal are in-kernel.
 * Context destruction is handled in-kernel
 *  GSS_Delete_sec_context is in-kernel
 *
 * Context creation is initiated by a RPCSEC_GSS_INIT request arriving.
 * The context handle and gss_token are used as a key into the rpcsec_init cache.
 * The content of this cache includes some of the outputs of GSS_Accept_sec_context,
 * being major_status, minor_status, context_handle, reply_token.
 * These are sent back to the client.
 * Sequence window management is handled by the kernel.  The window size if currently
 * a compile time constant.
 *
 * When user-space is happy that a context is established, it places an entry
 * in the rpcsec_context cache. The key for this cache is the context_handle.
 * The content includes:
 *   uid/gidlist - for determining access rights
 *   mechanism type
 *   mechanism specific information, such as a key
 *
 */

#include <linux/slab.h>
#include <linux/types.h>
#include <linux/module.h>
#include <linux/pagemap.h>
#include <linux/user_namespace.h>

#include <linux/sunrpc/auth_gss.h>
#include <linux/sunrpc/gss_err.h>
#include <linux/sunrpc/svcauth.h>
#include <linux/sunrpc/svcauth_gss.h>
#include <linux/sunrpc/cache.h>
#include <linux/sunrpc/gss_krb5.h>

#include <trace/events/rpcgss.h>

#include "gss_rpc_upcall.h"

/*
 * Unfortunately there isn't a maximum checksum size exported via the
 * GSS API. Manufacture one based on GSS mechanisms supported by this
 * implementation.
 */
#define GSS_MAX_CKSUMSIZE (GSS_KRB5_TOK_HDR_LEN + GSS_KRB5_MAX_CKSUM_LEN)

/*
 * This value may be increased in the future to accommodate other
 * usage of the scratch buffer.
 */
#define GSS_SCRATCH_SIZE GSS_MAX_CKSUMSIZE

struct gss_svc_data {
        /* decoded gss client cred: */
        struct rpc_gss_wire_cred        clcred;
        u32                             gsd_databody_offset;
        struct rsc                      *rsci;

        /* for temporary results */
        __be32                          gsd_seq_num;
        u8                              gsd_scratch[GSS_SCRATCH_SIZE];
};

/* The rpcsec_init cache is used for mapping RPCSEC_GSS_{,CONT_}INIT requests
 * into replies.
 *
 * Key is context handle (\x if empty) and gss_token.
 * Content is major_status minor_status (integers) context_handle, reply_token.
 *
 */

static int netobj_equal(struct xdr_netobj *a, struct xdr_netobj *b)
{
        return a->len == b->len && 0 == memcmp(a->data, b->data, a->len);
}

#define RSI_HASHBITS    6
#define RSI_HASHMAX     (1<<RSI_HASHBITS)

struct rsi {
        struct cache_head       h;
        struct xdr_netobj       in_handle, in_token;
        struct xdr_netobj       out_handle, out_token;
        int                     major_status, minor_status;
        struct rcu_head         rcu_head;
};

static struct rsi *rsi_update(struct cache_detail *cd, struct rsi *new, struct rsi *old);
static struct rsi *rsi_lookup(struct cache_detail *cd, struct rsi *item);

static void rsi_free(struct rsi *rsii)
{
        kfree(rsii->in_handle.data);
        kfree(rsii->in_token.data);
        kfree(rsii->out_handle.data);
        kfree(rsii->out_token.data);
}

static void rsi_free_rcu(struct rcu_head *head)
{
        struct rsi *rsii = container_of(head, struct rsi, rcu_head);

        rsi_free(rsii);
        kfree(rsii);
}

static void rsi_put(struct kref *ref)
{
        struct rsi *rsii = container_of(ref, struct rsi, h.ref);

        call_rcu(&rsii->rcu_head, rsi_free_rcu);
}

static inline int rsi_hash(struct rsi *item)
{
        return hash_mem(item->in_handle.data, item->in_handle.len, RSI_HASHBITS)
             ^ hash_mem(item->in_token.data, item->in_token.len, RSI_HASHBITS);
}

static int rsi_match(struct cache_head *a, struct cache_head *b)
{
        struct rsi *item = container_of(a, struct rsi, h);
        struct rsi *tmp = container_of(b, struct rsi, h);
        return netobj_equal(&item->in_handle, &tmp->in_handle) &&
               netobj_equal(&item->in_token, &tmp->in_token);
}

static int dup_to_netobj(struct xdr_netobj *dst, char *src, int len)
{
        dst->len = len;
        dst->data = (len ? kmemdup(src, len, GFP_KERNEL) : NULL);
        if (len && !dst->data)
                return -ENOMEM;
        return 0;
}

static inline int dup_netobj(struct xdr_netobj *dst, struct xdr_netobj *src)
{
        return dup_to_netobj(dst, src->data, src->len);
}

static void rsi_init(struct cache_head *cnew, struct cache_head *citem)
{
        struct rsi *new = container_of(cnew, struct rsi, h);
        struct rsi *item = container_of(citem, struct rsi, h);

        new->out_handle.data = NULL;
        new->out_handle.len = 0;
        new->out_token.data = NULL;
        new->out_token.len = 0;
        new->in_handle.len = item->in_handle.len;
        item->in_handle.len = 0;
        new->in_token.len = item->in_token.len;
        item->in_token.len = 0;
        new->in_handle.data = item->in_handle.data;
        item->in_handle.data = NULL;
        new->in_token.data = item->in_token.data;
        item->in_token.data = NULL;
}

static void update_rsi(struct cache_head *cnew, struct cache_head *citem)
{
        struct rsi *new = container_of(cnew, struct rsi, h);
        struct rsi *item = container_of(citem, struct rsi, h);

        BUG_ON(new->out_handle.data || new->out_token.data);
        new->out_handle.len = item->out_handle.len;
        item->out_handle.len = 0;
        new->out_token.len = item->out_token.len;
        item->out_token.len = 0;
        new->out_handle.data = item->out_handle.data;
        item->out_handle.data = NULL;
        new->out_token.data = item->out_token.data;
        item->out_token.data = NULL;

        new->major_status = item->major_status;
        new->minor_status = item->minor_status;
}

static struct cache_head *rsi_alloc(void)
{
        struct rsi *rsii = kmalloc_obj(*rsii);
        if (rsii)
                return &rsii->h;
        else
                return NULL;
}

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

static void rsi_request(struct cache_detail *cd,
                       struct cache_head *h,
                       char **bpp, int *blen)
{
        struct rsi *rsii = container_of(h, struct rsi, h);

        qword_addhex(bpp, blen, rsii->in_handle.data, rsii->in_handle.len);
        qword_addhex(bpp, blen, rsii->in_token.data, rsii->in_token.len);
        (*bpp)[-1] = '\n';
        WARN_ONCE(*blen < 0,
                  "RPCSEC/GSS credential too large - please use gssproxy\n");
}

static int rsi_parse(struct cache_detail *cd,
                    char *mesg, int mlen)
{
        /* context token expiry major minor context token */
        char *buf = mesg;
        char *ep;
        int len;
        struct rsi rsii, *rsip = NULL;
        time64_t expiry;
        int status = -EINVAL;

        memset(&rsii, 0, sizeof(rsii));
        /* handle */
        len = qword_get(&mesg, buf, mlen);
        if (len < 0)
                goto out;
        status = -ENOMEM;
        if (dup_to_netobj(&rsii.in_handle, buf, len))
                goto out;

        /* token */
        len = qword_get(&mesg, buf, mlen);
        status = -EINVAL;
        if (len < 0)
                goto out;
        status = -ENOMEM;
        if (dup_to_netobj(&rsii.in_token, buf, len))
                goto out;

        rsip = rsi_lookup(cd, &rsii);
        if (!rsip)
                goto out;

        rsii.h.flags = 0;
        /* expiry */
        status = get_expiry(&mesg, &expiry);
        if (status)
                goto out;

        status = -EINVAL;
        /* major/minor */
        len = qword_get(&mesg, buf, mlen);
        if (len <= 0)
                goto out;
        rsii.major_status = simple_strtoul(buf, &ep, 10);
        if (*ep)
                goto out;
        len = qword_get(&mesg, buf, mlen);
        if (len <= 0)
                goto out;
        rsii.minor_status = simple_strtoul(buf, &ep, 10);
        if (*ep)
                goto out;

        /* out_handle */
        len = qword_get(&mesg, buf, mlen);
        if (len < 0)
                goto out;
        status = -ENOMEM;
        if (dup_to_netobj(&rsii.out_handle, buf, len))
                goto out;

        /* out_token */
        len = qword_get(&mesg, buf, mlen);
        status = -EINVAL;
        if (len < 0)
                goto out;
        status = -ENOMEM;
        if (dup_to_netobj(&rsii.out_token, buf, len))
                goto out;
        rsii.h.expiry_time = expiry;
        rsip = rsi_update(cd, &rsii, rsip);
        status = 0;
out:
        rsi_free(&rsii);
        if (rsip)
                cache_put(&rsip->h, cd);
        else
                status = -ENOMEM;
        return status;
}

static const struct cache_detail rsi_cache_template = {
        .owner          = THIS_MODULE,
        .hash_size      = RSI_HASHMAX,
        .name           = "auth.rpcsec.init",
        .cache_put      = rsi_put,
        .cache_upcall   = rsi_upcall,
        .cache_request  = rsi_request,
        .cache_parse    = rsi_parse,
        .match          = rsi_match,
        .init           = rsi_init,
        .update         = update_rsi,
        .alloc          = rsi_alloc,
};

static struct rsi *rsi_lookup(struct cache_detail *cd, struct rsi *item)
{
        struct cache_head *ch;
        int hash = rsi_hash(item);

        ch = sunrpc_cache_lookup_rcu(cd, &item->h, hash);
        if (ch)
                return container_of(ch, struct rsi, h);
        else
                return NULL;
}

static struct rsi *rsi_update(struct cache_detail *cd, struct rsi *new, struct rsi *old)
{
        struct cache_head *ch;
        int hash = rsi_hash(new);

        ch = sunrpc_cache_update(cd, &new->h,
                                 &old->h, hash);
        if (ch)
                return container_of(ch, struct rsi, h);
        else
                return NULL;
}


/*
 * The rpcsec_context cache is used to store a context that is
 * used in data exchange.
 * The key is a context handle. The content is:
 *  uid, gidlist, mechanism, service-set, mech-specific-data
 */

#define RSC_HASHBITS    10
#define RSC_HASHMAX     (1<<RSC_HASHBITS)

#define GSS_SEQ_WIN     128

struct gss_svc_seq_data {
        /* highest seq number seen so far: */
        u32                     sd_max;
        /* for i such that sd_max-GSS_SEQ_WIN < i <= sd_max, the i-th bit of
         * sd_win is nonzero iff sequence number i has been seen already: */
        unsigned long           sd_win[GSS_SEQ_WIN/BITS_PER_LONG];
        spinlock_t              sd_lock;
};

struct rsc {
        struct cache_head       h;
        struct xdr_netobj       handle;
        struct svc_cred         cred;
        struct gss_svc_seq_data seqdata;
        struct gss_ctx          *mechctx;
        struct rcu_head         rcu_head;
};

static struct rsc *rsc_update(struct cache_detail *cd, struct rsc *new, struct rsc *old);
static struct rsc *rsc_lookup(struct cache_detail *cd, struct rsc *item);

static void rsc_free(struct rsc *rsci)
{
        kfree(rsci->handle.data);
        if (rsci->mechctx)
                gss_delete_sec_context(&rsci->mechctx);
        free_svc_cred(&rsci->cred);
}

static void rsc_free_rcu(struct rcu_head *head)
{
        struct rsc *rsci = container_of(head, struct rsc, rcu_head);

        kfree(rsci->handle.data);
        kfree(rsci);
}

static void rsc_put(struct kref *ref)
{
        struct rsc *rsci = container_of(ref, struct rsc, h.ref);

        if (rsci->mechctx)
                gss_delete_sec_context(&rsci->mechctx);
        free_svc_cred(&rsci->cred);
        call_rcu(&rsci->rcu_head, rsc_free_rcu);
}

static inline int
rsc_hash(struct rsc *rsci)
{
        return hash_mem(rsci->handle.data, rsci->handle.len, RSC_HASHBITS);
}

static int
rsc_match(struct cache_head *a, struct cache_head *b)
{
        struct rsc *new = container_of(a, struct rsc, h);
        struct rsc *tmp = container_of(b, struct rsc, h);

        return netobj_equal(&new->handle, &tmp->handle);
}

static void
rsc_init(struct cache_head *cnew, struct cache_head *ctmp)
{
        struct rsc *new = container_of(cnew, struct rsc, h);
        struct rsc *tmp = container_of(ctmp, struct rsc, h);

        new->handle.len = tmp->handle.len;
        tmp->handle.len = 0;
        new->handle.data = tmp->handle.data;
        tmp->handle.data = NULL;
        new->mechctx = NULL;
        init_svc_cred(&new->cred);
}

static void
update_rsc(struct cache_head *cnew, struct cache_head *ctmp)
{
        struct rsc *new = container_of(cnew, struct rsc, h);
        struct rsc *tmp = container_of(ctmp, struct rsc, h);

        new->mechctx = tmp->mechctx;
        tmp->mechctx = NULL;
        memset(&new->seqdata, 0, sizeof(new->seqdata));
        spin_lock_init(&new->seqdata.sd_lock);
        new->cred = tmp->cred;
        init_svc_cred(&tmp->cred);
}

static struct cache_head *
rsc_alloc(void)
{
        struct rsc *rsci = kmalloc_obj(*rsci);
        if (rsci)
                return &rsci->h;
        else
                return NULL;
}

static int rsc_upcall(struct cache_detail *cd, struct cache_head *h)
{
        return -EINVAL;
}

static int rsc_parse(struct cache_detail *cd,
                     char *mesg, int mlen)
{
        /* contexthandle expiry [ uid gid N <n gids> mechname ...mechdata... ] */
        char *buf = mesg;
        int id;
        int len, rv;
        struct rsc rsci, *rscp = NULL;
        time64_t expiry;
        int status = -EINVAL;
        struct gss_api_mech *gm = NULL;

        memset(&rsci, 0, sizeof(rsci));
        /* context handle */
        len = qword_get(&mesg, buf, mlen);
        if (len < 0) goto out;
        status = -ENOMEM;
        if (dup_to_netobj(&rsci.handle, buf, len))
                goto out;

        rsci.h.flags = 0;
        /* expiry */
        status = get_expiry(&mesg, &expiry);
        if (status)
                goto out;

        status = -EINVAL;
        rscp = rsc_lookup(cd, &rsci);
        if (!rscp)
                goto out;

        /* uid, or NEGATIVE */
        rv = get_int(&mesg, &id);
        if (rv == -EINVAL)
                goto out;
        if (rv == -ENOENT)
                set_bit(CACHE_NEGATIVE, &rsci.h.flags);
        else {
                int N, i;

                /*
                 * NOTE: we skip uid_valid()/gid_valid() checks here:
                 * instead, * -1 id's are later mapped to the
                 * (export-specific) anonymous id by nfsd_setuser.
                 *
                 * (But supplementary gid's get no such special
                 * treatment so are checked for validity here.)
                 */
                /* uid */
                rsci.cred.cr_uid = make_kuid(current_user_ns(), id);

                /* gid */
                if (get_int(&mesg, &id))
                        goto out;
                rsci.cred.cr_gid = make_kgid(current_user_ns(), id);

                /* number of additional gid's */
                if (get_int(&mesg, &N))
                        goto out;
                if (N < 0 || N > NGROUPS_MAX)
                        goto out;
                status = -ENOMEM;
                rsci.cred.cr_group_info = groups_alloc(N);
                if (rsci.cred.cr_group_info == NULL)
                        goto out;

                /* gid's */
                status = -EINVAL;
                for (i=0; i<N; i++) {
                        kgid_t kgid;
                        if (get_int(&mesg, &id))
                                goto out;
                        kgid = make_kgid(current_user_ns(), id);
                        if (!gid_valid(kgid))
                                goto out;
                        rsci.cred.cr_group_info->gid[i] = kgid;
                }
                groups_sort(rsci.cred.cr_group_info);

                /* mech name */
                len = qword_get(&mesg, buf, mlen);
                if (len < 0)
                        goto out;
                gm = rsci.cred.cr_gss_mech = gss_mech_get_by_name(buf);
                status = -EOPNOTSUPP;
                if (!gm)
                        goto out;

                status = -EINVAL;
                /* mech-specific data: */
                len = qword_get(&mesg, buf, mlen);
                if (len < 0)
                        goto out;
                status = gss_import_sec_context(buf, len, gm, &rsci.mechctx,
                                                NULL, GFP_KERNEL);
                if (status)
                        goto out;

                /* get client name */
                len = qword_get(&mesg, buf, mlen);
                if (len > 0) {
                        rsci.cred.cr_principal = kstrdup(buf, GFP_KERNEL);
                        if (!rsci.cred.cr_principal) {
                                status = -ENOMEM;
                                goto out;
                        }
                }

        }
        rsci.h.expiry_time = expiry;
        rscp = rsc_update(cd, &rsci, rscp);
        status = 0;
out:
        rsc_free(&rsci);
        if (rscp)
                cache_put(&rscp->h, cd);
        else
                status = -ENOMEM;
        return status;
}

static const struct cache_detail rsc_cache_template = {
        .owner          = THIS_MODULE,
        .hash_size      = RSC_HASHMAX,
        .name           = "auth.rpcsec.context",
        .cache_put      = rsc_put,
        .cache_upcall   = rsc_upcall,
        .cache_parse    = rsc_parse,
        .match          = rsc_match,
        .init           = rsc_init,
        .update         = update_rsc,
        .alloc          = rsc_alloc,
};

static struct rsc *rsc_lookup(struct cache_detail *cd, struct rsc *item)
{
        struct cache_head *ch;
        int hash = rsc_hash(item);

        ch = sunrpc_cache_lookup_rcu(cd, &item->h, hash);
        if (ch)
                return container_of(ch, struct rsc, h);
        else
                return NULL;
}

static struct rsc *rsc_update(struct cache_detail *cd, struct rsc *new, struct rsc *old)
{
        struct cache_head *ch;
        int hash = rsc_hash(new);

        ch = sunrpc_cache_update(cd, &new->h,
                                 &old->h, hash);
        if (ch)
                return container_of(ch, struct rsc, h);
        else
                return NULL;
}


static struct rsc *
gss_svc_searchbyctx(struct cache_detail *cd, struct xdr_netobj *handle)
{
        struct rsc rsci;
        struct rsc *found;

        memset(&rsci, 0, sizeof(rsci));
        if (dup_to_netobj(&rsci.handle, handle->data, handle->len))
                return NULL;
        found = rsc_lookup(cd, &rsci);
        rsc_free(&rsci);
        if (!found)
                return NULL;
        if (cache_check(cd, &found->h, NULL))
                return NULL;
        return found;
}

/**
 * gss_check_seq_num - GSS sequence number window check
 * @rqstp: RPC Call to use when reporting errors
 * @rsci: cached GSS context state (updated on return)
 * @seq_num: sequence number to check
 *
 * Implements sequence number algorithm as specified in
 * RFC 2203, Section 5.3.3.1. "Context Management".
 *
 * Return values:
 *   %true: @rqstp's GSS sequence number is inside the window
 *   %false: @rqstp's GSS sequence number is outside the window
 */
static bool gss_check_seq_num(const struct svc_rqst *rqstp, struct rsc *rsci,
                              u32 seq_num)
{
        struct gss_svc_seq_data *sd = &rsci->seqdata;
        bool result = false;

        spin_lock(&sd->sd_lock);
        if (seq_num > sd->sd_max) {
                if (seq_num >= sd->sd_max + GSS_SEQ_WIN) {
                        memset(sd->sd_win, 0, sizeof(sd->sd_win));
                        sd->sd_max = seq_num;
                } else while (sd->sd_max < seq_num) {
                        sd->sd_max++;
                        __clear_bit(sd->sd_max % GSS_SEQ_WIN, sd->sd_win);
                }
                __set_bit(seq_num % GSS_SEQ_WIN, sd->sd_win);
                goto ok;
        } else if (seq_num + GSS_SEQ_WIN <= sd->sd_max) {
                goto toolow;
        }
        if (__test_and_set_bit(seq_num % GSS_SEQ_WIN, sd->sd_win))
                goto alreadyseen;

ok:
        result = true;
out:
        spin_unlock(&sd->sd_lock);
        return result;

toolow:
        trace_rpcgss_svc_seqno_low(rqstp, seq_num,
                                   sd->sd_max - GSS_SEQ_WIN,
                                   sd->sd_max);
        goto out;
alreadyseen:
        trace_rpcgss_svc_seqno_seen(rqstp, seq_num);
        goto out;
}

/*
 * Decode and verify a Call's verifier field. For RPC_AUTH_GSS Calls,
 * the body of this field contains a variable length checksum.
 *
 * GSS-specific auth_stat values are mandated by RFC 2203 Section
 * 5.3.3.3.
 */
static int
svcauth_gss_verify_header(struct svc_rqst *rqstp, struct rsc *rsci,
                          __be32 *rpcstart, struct rpc_gss_wire_cred *gc)
{
        struct xdr_stream       *xdr = &rqstp->rq_arg_stream;
        struct gss_ctx          *ctx_id = rsci->mechctx;
        u32                     flavor, maj_stat;
        struct xdr_buf          rpchdr;
        struct xdr_netobj       checksum;
        struct kvec             iov;

        /*
         * Compute the checksum of the incoming Call from the
         * XID field to credential field:
         */
        iov.iov_base = rpcstart;
        iov.iov_len = (u8 *)xdr->p - (u8 *)rpcstart;
        xdr_buf_from_iov(&iov, &rpchdr);

        /* Call's verf field: */
        if (xdr_stream_decode_opaque_auth(xdr, &flavor,
                                          (void **)&checksum.data,
                                          &checksum.len) < 0) {
                rqstp->rq_auth_stat = rpc_autherr_badverf;
                return SVC_DENIED;
        }
        if (flavor != RPC_AUTH_GSS || checksum.len < XDR_UNIT) {
                rqstp->rq_auth_stat = rpc_autherr_badverf;
                return SVC_DENIED;
        }

        if (rqstp->rq_deferred)
                return SVC_OK;
        maj_stat = gss_verify_mic(ctx_id, &rpchdr, &checksum);
        if (maj_stat != GSS_S_COMPLETE) {
                trace_rpcgss_svc_mic(rqstp, maj_stat);
                rqstp->rq_auth_stat = rpcsec_gsserr_credproblem;
                return SVC_DENIED;
        }

        if (gc->gc_seq > MAXSEQ) {
                trace_rpcgss_svc_seqno_large(rqstp, gc->gc_seq);
                rqstp->rq_auth_stat = rpcsec_gsserr_ctxproblem;
                return SVC_DENIED;
        }
        if (!gss_check_seq_num(rqstp, rsci, gc->gc_seq))
                return SVC_DROP;
        return SVC_OK;
}

/*
 * Construct and encode a Reply's verifier field. The verifier's body
 * field contains a variable-length checksum of the GSS sequence
 * number.
 */
static bool
svcauth_gss_encode_verf(struct svc_rqst *rqstp, struct gss_ctx *ctx_id, u32 seq)
{
        struct gss_svc_data     *gsd = rqstp->rq_auth_data;
        u32                     maj_stat;
        struct xdr_buf          verf_data;
        struct xdr_netobj       checksum;
        struct kvec             iov;

        gsd->gsd_seq_num = cpu_to_be32(seq);
        iov.iov_base = &gsd->gsd_seq_num;
        iov.iov_len = XDR_UNIT;
        xdr_buf_from_iov(&iov, &verf_data);

        checksum.data = gsd->gsd_scratch;
        maj_stat = gss_get_mic(ctx_id, &verf_data, &checksum);
        if (maj_stat != GSS_S_COMPLETE)
                goto bad_mic;

        return xdr_stream_encode_opaque_auth(&rqstp->rq_res_stream, RPC_AUTH_GSS,
                                             checksum.data, checksum.len) > 0;

bad_mic:
        trace_rpcgss_svc_get_mic(rqstp, maj_stat);
        return false;
}

struct gss_domain {
        struct auth_domain      h;
        u32                     pseudoflavor;
};

static struct auth_domain *
find_gss_auth_domain(struct gss_ctx *ctx, u32 svc)
{
        char *name;

        name = gss_service_to_auth_domain_name(ctx->mech_type, svc);
        if (!name)
                return NULL;
        return auth_domain_find(name);
}

static struct auth_ops svcauthops_gss;

u32 svcauth_gss_flavor(struct auth_domain *dom)
{
        struct gss_domain *gd = container_of(dom, struct gss_domain, h);

        return gd->pseudoflavor;
}

EXPORT_SYMBOL_GPL(svcauth_gss_flavor);

struct auth_domain *
svcauth_gss_register_pseudoflavor(u32 pseudoflavor, char * name)
{
        struct gss_domain       *new;
        struct auth_domain      *test;
        int                     stat = -ENOMEM;

        new = kmalloc_obj(*new);
        if (!new)
                goto out;
        kref_init(&new->h.ref);
        new->h.name = kstrdup(name, GFP_KERNEL);
        if (!new->h.name)
                goto out_free_dom;
        new->h.flavour = &svcauthops_gss;
        new->pseudoflavor = pseudoflavor;

        test = auth_domain_lookup(name, &new->h);
        if (test != &new->h) {
                pr_warn("svc: duplicate registration of gss pseudo flavour %s.\n",
                        name);
                stat = -EADDRINUSE;
                auth_domain_put(test);
                goto out_free_name;
        }
        return test;

out_free_name:
        kfree(new->h.name);
out_free_dom:
        kfree(new);
out:
        return ERR_PTR(stat);
}
EXPORT_SYMBOL_GPL(svcauth_gss_register_pseudoflavor);

/*
 * RFC 2203, Section 5.3.2.2
 *
 *      struct rpc_gss_integ_data {
 *              opaque databody_integ<>;
 *              opaque checksum<>;
 *      };
 *
 *      struct rpc_gss_data_t {
 *              unsigned int seq_num;
 *              proc_req_arg_t arg;
 *      };
 */
static noinline_for_stack int
svcauth_gss_unwrap_integ(struct svc_rqst *rqstp, u32 seq, struct gss_ctx *ctx)
{
        struct gss_svc_data *gsd = rqstp->rq_auth_data;
        struct xdr_stream *xdr = &rqstp->rq_arg_stream;
        u32 len, offset, seq_num, maj_stat;
        struct xdr_buf *buf = xdr->buf;
        struct xdr_buf databody_integ;
        struct xdr_netobj checksum;

        /* Did we already verify the signature on the original pass through? */
        if (rqstp->rq_deferred)
                return 0;

        if (xdr_stream_decode_u32(xdr, &len) < 0)
                goto unwrap_failed;
        if (len & 3)
                goto unwrap_failed;
        offset = xdr_stream_pos(xdr);
        if (xdr_buf_subsegment(buf, &databody_integ, offset, len))
                goto unwrap_failed;

        /*
         * The xdr_stream now points to the @seq_num field. The next
         * XDR data item is the @arg field, which contains the clear
         * text RPC program payload. The checksum, which follows the
         * @arg field, is located and decoded without updating the
         * xdr_stream.
         */

        offset += len;
        if (xdr_decode_word(buf, offset, &checksum.len))
                goto unwrap_failed;
        if (checksum.len > sizeof(gsd->gsd_scratch))
                goto unwrap_failed;
        checksum.data = gsd->gsd_scratch;
        if (read_bytes_from_xdr_buf(buf, offset + XDR_UNIT, checksum.data,
                                    checksum.len))
                goto unwrap_failed;

        maj_stat = gss_verify_mic(ctx, &databody_integ, &checksum);
        if (maj_stat != GSS_S_COMPLETE)
                goto bad_mic;

        /* The received seqno is protected by the checksum. */
        if (xdr_stream_decode_u32(xdr, &seq_num) < 0)
                goto unwrap_failed;
        if (seq_num != seq)
                goto bad_seqno;

        xdr_truncate_decode(xdr, XDR_UNIT + checksum.len);
        return 0;

unwrap_failed:
        trace_rpcgss_svc_unwrap_failed(rqstp);
        return -EINVAL;
bad_seqno:
        trace_rpcgss_svc_seqno_bad(rqstp, seq, seq_num);
        return -EINVAL;
bad_mic:
        trace_rpcgss_svc_mic(rqstp, maj_stat);
        return -EINVAL;
}

/*
 * RFC 2203, Section 5.3.2.3
 *
 *      struct rpc_gss_priv_data {
 *              opaque databody_priv<>
 *      };
 *
 *      struct rpc_gss_data_t {
 *              unsigned int seq_num;
 *              proc_req_arg_t arg;
 *      };
 */
static noinline_for_stack int
svcauth_gss_unwrap_priv(struct svc_rqst *rqstp, u32 seq, struct gss_ctx *ctx)
{
        struct xdr_stream *xdr = &rqstp->rq_arg_stream;
        u32 len, maj_stat, seq_num, offset;
        struct xdr_buf *buf = xdr->buf;
        unsigned int saved_len;

        if (xdr_stream_decode_u32(xdr, &len) < 0)
                goto unwrap_failed;
        if (rqstp->rq_deferred) {
                /* Already decrypted last time through! The sequence number
                 * check at out_seq is unnecessary but harmless: */
                goto out_seq;
        }
        if (len > xdr_stream_remaining(xdr))
                goto unwrap_failed;
        offset = xdr_stream_pos(xdr);

        saved_len = buf->len;
        maj_stat = gss_unwrap(ctx, offset, offset + len, buf);
        if (maj_stat != GSS_S_COMPLETE)
                goto bad_unwrap;
        xdr->nwords -= XDR_QUADLEN(saved_len - buf->len);

out_seq:
        /* gss_unwrap() decrypted the sequence number. */
        if (xdr_stream_decode_u32(xdr, &seq_num) < 0)
                goto unwrap_failed;
        if (seq_num != seq)
                goto bad_seqno;
        return 0;

unwrap_failed:
        trace_rpcgss_svc_unwrap_failed(rqstp);
        return -EINVAL;
bad_seqno:
        trace_rpcgss_svc_seqno_bad(rqstp, seq, seq_num);
        return -EINVAL;
bad_unwrap:
        trace_rpcgss_svc_unwrap(rqstp, maj_stat);
        return -EINVAL;
}

static enum svc_auth_status
svcauth_gss_set_client(struct svc_rqst *rqstp)
{
        struct gss_svc_data *svcdata = rqstp->rq_auth_data;
        struct rsc *rsci = svcdata->rsci;
        struct rpc_gss_wire_cred *gc = &svcdata->clcred;
        int stat;

        rqstp->rq_auth_stat = rpc_autherr_badcred;

        /*
         * A gss export can be specified either by:
         *      export  *(sec=krb5,rw)
         * or by
         *      export gss/krb5(rw)
         * The latter is deprecated; but for backwards compatibility reasons
         * the nfsd code will still fall back on trying it if the former
         * doesn't work; so we try to make both available to nfsd, below.
         */
        rqstp->rq_gssclient = find_gss_auth_domain(rsci->mechctx, gc->gc_svc);
        if (rqstp->rq_gssclient == NULL)
                return SVC_DENIED;
        stat = svcauth_unix_set_client(rqstp);
        if (stat == SVC_DROP || stat == SVC_CLOSE)
                return stat;

        rqstp->rq_auth_stat = rpc_auth_ok;
        return SVC_OK;
}

static bool
svcauth_gss_proc_init_verf(struct cache_detail *cd, struct svc_rqst *rqstp,
                           struct xdr_netobj *out_handle, int *major_status,
                           u32 seq_num)
{
        struct xdr_stream *xdr = &rqstp->rq_res_stream;
        struct rsc *rsci;
        bool rc;

        if (*major_status != GSS_S_COMPLETE)
                goto null_verifier;
        rsci = gss_svc_searchbyctx(cd, out_handle);
        if (rsci == NULL) {
                *major_status = GSS_S_NO_CONTEXT;
                goto null_verifier;
        }

        rc = svcauth_gss_encode_verf(rqstp, rsci->mechctx, seq_num);
        cache_put(&rsci->h, cd);
        return rc;

null_verifier:
        return xdr_stream_encode_opaque_auth(xdr, RPC_AUTH_NULL, NULL, 0) > 0;
}

static void gss_free_in_token_pages(struct gssp_in_token *in_token)
{
        int i;

        i = 0;
        while (in_token->pages[i])
                put_page(in_token->pages[i++]);
        kfree(in_token->pages);
        in_token->pages = NULL;
}

static int gss_read_proxy_verf(struct svc_rqst *rqstp,
                               struct rpc_gss_wire_cred *gc,
                               struct xdr_netobj *in_handle,
                               struct gssp_in_token *in_token)
{
        struct xdr_stream *xdr = &rqstp->rq_arg_stream;
        unsigned int length, pgto_offs, pgfrom_offs;
        int pages, i, pgto, pgfrom;
        size_t to_offs, from_offs;
        u32 inlen;

        if (dup_netobj(in_handle, &gc->gc_ctx))
                return SVC_CLOSE;

        /*
         *  RFC 2203 Section 5.2.2
         *
         *      struct rpc_gss_init_arg {
         *              opaque gss_token<>;
         *      };
         */
        if (xdr_stream_decode_u32(xdr, &inlen) < 0)
                goto out_denied_free;
        if (inlen > xdr_stream_remaining(xdr))
                goto out_denied_free;

        pages = DIV_ROUND_UP(inlen, PAGE_SIZE);
        in_token->pages = kzalloc_objs(struct page *, pages + 1);
        if (!in_token->pages)
                goto out_denied_free;
        in_token->page_base = 0;
        in_token->page_len = inlen;
        for (i = 0; i < pages; i++) {
                in_token->pages[i] = alloc_page(GFP_KERNEL);
                if (!in_token->pages[i]) {
                        gss_free_in_token_pages(in_token);
                        goto out_denied_free;
                }
        }

        length = min_t(unsigned int, inlen, (char *)xdr->end - (char *)xdr->p);
        if (length)
                memcpy(page_address(in_token->pages[0]), xdr->p, length);
        inlen -= length;

        to_offs = length;
        from_offs = rqstp->rq_arg.page_base;
        while (inlen) {
                pgto = to_offs >> PAGE_SHIFT;
                pgfrom = from_offs >> PAGE_SHIFT;
                pgto_offs = to_offs & ~PAGE_MASK;
                pgfrom_offs = from_offs & ~PAGE_MASK;

                length = min_t(unsigned int, inlen,
                         min_t(unsigned int, PAGE_SIZE - pgto_offs,
                               PAGE_SIZE - pgfrom_offs));
                memcpy(page_address(in_token->pages[pgto]) + pgto_offs,
                       page_address(rqstp->rq_arg.pages[pgfrom]) + pgfrom_offs,
                       length);

                to_offs += length;
                from_offs += length;
                inlen -= length;
        }
        return 0;

out_denied_free:
        kfree(in_handle->data);
        return SVC_DENIED;
}

/*
 * RFC 2203, Section 5.2.3.1.
 *
 *      struct rpc_gss_init_res {
 *              opaque handle<>;
 *              unsigned int gss_major;
 *              unsigned int gss_minor;
 *              unsigned int seq_window;
 *              opaque gss_token<>;
 *      };
 */
static bool
svcxdr_encode_gss_init_res(struct xdr_stream *xdr,
                           struct xdr_netobj *handle,
                           struct xdr_netobj *gss_token,
                           unsigned int major_status,
                           unsigned int minor_status, u32 seq_num)
{
        if (xdr_stream_encode_opaque(xdr, handle->data, handle->len) < 0)
                return false;
        if (xdr_stream_encode_u32(xdr, major_status) < 0)
                return false;
        if (xdr_stream_encode_u32(xdr, minor_status) < 0)
                return false;
        if (xdr_stream_encode_u32(xdr, seq_num) < 0)
                return false;
        if (xdr_stream_encode_opaque(xdr, gss_token->data, gss_token->len) < 0)
                return false;
        return true;
}

/*
 * Having read the cred already and found we're in the context
 * initiation case, read the verifier and initiate (or check the results
 * of) upcalls to userspace for help with context initiation.  If
 * the upcall results are available, write the verifier and result.
 * Otherwise, drop the request pending an answer to the upcall.
 */
static int
svcauth_gss_legacy_init(struct svc_rqst *rqstp,
                        struct rpc_gss_wire_cred *gc)
{
        struct xdr_stream *xdr = &rqstp->rq_arg_stream;
        struct rsi *rsip, rsikey;
        __be32 *p;
        u32 len;
        int ret;
        struct sunrpc_net *sn = net_generic(SVC_NET(rqstp), sunrpc_net_id);

        memset(&rsikey, 0, sizeof(rsikey));
        if (dup_netobj(&rsikey.in_handle, &gc->gc_ctx))
                return SVC_CLOSE;

        /*
         *  RFC 2203 Section 5.2.2
         *
         *      struct rpc_gss_init_arg {
         *              opaque gss_token<>;
         *      };
         */
        if (xdr_stream_decode_u32(xdr, &len) < 0) {
                kfree(rsikey.in_handle.data);
                return SVC_DENIED;
        }
        p = xdr_inline_decode(xdr, len);
        if (!p) {
                kfree(rsikey.in_handle.data);
                return SVC_DENIED;
        }
        rsikey.in_token.data = kmalloc(len, GFP_KERNEL);
        if (ZERO_OR_NULL_PTR(rsikey.in_token.data)) {
                kfree(rsikey.in_handle.data);
                return SVC_CLOSE;
        }
        memcpy(rsikey.in_token.data, p, len);
        rsikey.in_token.len = len;

        /* Perform upcall, or find upcall result: */
        rsip = rsi_lookup(sn->rsi_cache, &rsikey);
        rsi_free(&rsikey);
        if (!rsip)
                return SVC_CLOSE;
        if (cache_check(sn->rsi_cache, &rsip->h, &rqstp->rq_chandle) < 0)
                /* No upcall result: */
                return SVC_CLOSE;

        ret = SVC_CLOSE;
        if (!svcauth_gss_proc_init_verf(sn->rsc_cache, rqstp, &rsip->out_handle,
                                        &rsip->major_status, GSS_SEQ_WIN))
                goto out;
        if (!svcxdr_set_accept_stat(rqstp))
                goto out;
        if (!svcxdr_encode_gss_init_res(&rqstp->rq_res_stream, &rsip->out_handle,
                                        &rsip->out_token, rsip->major_status,
                                        rsip->minor_status, GSS_SEQ_WIN))
                goto out;

        ret = SVC_COMPLETE;
out:
        cache_put(&rsip->h, sn->rsi_cache);
        return ret;
}

static int gss_proxy_save_rsc(struct cache_detail *cd,
                                struct gssp_upcall_data *ud,
                                uint64_t *handle)
{
        struct rsc rsci, *rscp = NULL;
        static atomic64_t ctxhctr;
        long long ctxh;
        struct gss_api_mech *gm = NULL;
        time64_t expiry;
        int status;

        memset(&rsci, 0, sizeof(rsci));
        /* context handle */
        status = -ENOMEM;
        /* the handle needs to be just a unique id,
         * use a static counter */
        ctxh = atomic64_inc_return(&ctxhctr);

        /* make a copy for the caller */
        *handle = ctxh;

        /* make a copy for the rsc cache */
        if (dup_to_netobj(&rsci.handle, (char *)handle, sizeof(uint64_t)))
                goto out;
        rscp = rsc_lookup(cd, &rsci);
        if (!rscp)
                goto out;

        /* creds */
        if (!ud->found_creds) {
                /* userspace seem buggy, we should always get at least a
                 * mapping to nobody */
                goto out;
        } else {
                struct timespec64 boot;

                /* steal creds */
                rsci.cred = ud->creds;
                memset(&ud->creds, 0, sizeof(struct svc_cred));

                status = -EOPNOTSUPP;
                /* get mech handle from OID */
                gm = gss_mech_get_by_OID(&ud->mech_oid);
                if (!gm)
                        goto out;
                rsci.cred.cr_gss_mech = gm;

                status = -EINVAL;
                /* mech-specific data: */
                status = gss_import_sec_context(ud->out_handle.data,
                                                ud->out_handle.len,
                                                gm, &rsci.mechctx,
                                                &expiry, GFP_KERNEL);
                if (status)
                        goto out;

                getboottime64(&boot);
                expiry -= boot.tv_sec;
        }

        rsci.h.expiry_time = expiry;
        rscp = rsc_update(cd, &rsci, rscp);
        status = 0;
out:
        rsc_free(&rsci);
        if (rscp)
                cache_put(&rscp->h, cd);
        else
                status = -ENOMEM;
        return status;
}

static int svcauth_gss_proxy_init(struct svc_rqst *rqstp,
                                  struct rpc_gss_wire_cred *gc)
{
        struct xdr_netobj cli_handle;
        struct gssp_upcall_data ud;
        uint64_t handle;
        int status;
        int ret;
        struct net *net = SVC_NET(rqstp);
        struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);

        memset(&ud, 0, sizeof(ud));
        ret = gss_read_proxy_verf(rqstp, gc, &ud.in_handle, &ud.in_token);
        if (ret)
                return ret;

        ret = SVC_CLOSE;

        /* Perform synchronous upcall to gss-proxy */
        status = gssp_accept_sec_context_upcall(net, &ud);
        if (status)
                goto out;

        trace_rpcgss_svc_accept_upcall(rqstp, ud.major_status, ud.minor_status);

        switch (ud.major_status) {
        case GSS_S_CONTINUE_NEEDED:
                cli_handle = ud.out_handle;
                break;
        case GSS_S_COMPLETE:
                status = gss_proxy_save_rsc(sn->rsc_cache, &ud, &handle);
                if (status)
                        goto out;
                cli_handle.data = (u8 *)&handle;
                cli_handle.len = sizeof(handle);
                break;
        default:
                goto out;
        }

        if (!svcauth_gss_proc_init_verf(sn->rsc_cache, rqstp, &cli_handle,
                                        &ud.major_status, GSS_SEQ_WIN))
                goto out;
        if (!svcxdr_set_accept_stat(rqstp))
                goto out;
        if (!svcxdr_encode_gss_init_res(&rqstp->rq_res_stream, &cli_handle,
                                        &ud.out_token, ud.major_status,
                                        ud.minor_status, GSS_SEQ_WIN))
                goto out;

        ret = SVC_COMPLETE;
out:
        gss_free_in_token_pages(&ud.in_token);
        gssp_free_upcall_data(&ud);
        return ret;
}

/*
 * Try to set the sn->use_gss_proxy variable to a new value. We only allow
 * it to be changed if it's currently undefined (-1). If it's any other value
 * then return -EBUSY unless the type wouldn't have changed anyway.
 */
static int set_gss_proxy(struct net *net, int type)
{
        struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
        int ret;

        WARN_ON_ONCE(type != 0 && type != 1);
        ret = cmpxchg(&sn->use_gss_proxy, -1, type);
        if (ret != -1 && ret != type)
                return -EBUSY;
        return 0;
}

static bool use_gss_proxy(struct net *net)
{
        struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);

        /* If use_gss_proxy is still undefined, then try to disable it */
        if (sn->use_gss_proxy == -1)
                set_gss_proxy(net, 0);
        return sn->use_gss_proxy;
}

static noinline_for_stack int
svcauth_gss_proc_init(struct svc_rqst *rqstp, struct rpc_gss_wire_cred *gc)
{
        struct xdr_stream *xdr = &rqstp->rq_arg_stream;
        u32 flavor, len;
        void *body;

        /* Call's verf field: */
        if (xdr_stream_decode_opaque_auth(xdr, &flavor, &body, &len) < 0)
                return SVC_GARBAGE;
        if (flavor != RPC_AUTH_NULL || len != 0) {
                rqstp->rq_auth_stat = rpc_autherr_badverf;
                return SVC_DENIED;
        }

        if (gc->gc_proc == RPC_GSS_PROC_INIT && gc->gc_ctx.len != 0) {
                rqstp->rq_auth_stat = rpc_autherr_badcred;
                return SVC_DENIED;
        }

        if (!use_gss_proxy(SVC_NET(rqstp)))
                return svcauth_gss_legacy_init(rqstp, gc);
        return svcauth_gss_proxy_init(rqstp, gc);
}

#ifdef CONFIG_PROC_FS

static ssize_t write_gssp(struct file *file, const char __user *buf,
                         size_t count, loff_t *ppos)
{
        struct net *net = pde_data(file_inode(file));
        char tbuf[20];
        unsigned long i;
        int res;

        if (*ppos || count > sizeof(tbuf)-1)
                return -EINVAL;
        if (copy_from_user(tbuf, buf, count))
                return -EFAULT;

        tbuf[count] = 0;
        res = kstrtoul(tbuf, 0, &i);
        if (res)
                return res;
        if (i != 1)
                return -EINVAL;
        res = set_gssp_clnt(net);
        if (res)
                return res;
        res = set_gss_proxy(net, 1);
        if (res)
                return res;
        return count;
}

static ssize_t read_gssp(struct file *file, char __user *buf,
                         size_t count, loff_t *ppos)
{
        struct net *net = pde_data(file_inode(file));
        struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
        unsigned long p = *ppos;
        char tbuf[10];
        size_t len;

        snprintf(tbuf, sizeof(tbuf), "%d\n", sn->use_gss_proxy);
        len = strlen(tbuf);
        if (p >= len)
                return 0;
        len -= p;
        if (len > count)
                len = count;
        if (copy_to_user(buf, (void *)(tbuf+p), len))
                return -EFAULT;
        *ppos += len;
        return len;
}

static const struct proc_ops use_gss_proxy_proc_ops = {
        .proc_open      = nonseekable_open,
        .proc_write     = write_gssp,
        .proc_read      = read_gssp,
};

static int create_use_gss_proxy_proc_entry(struct net *net)
{
        struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
        struct proc_dir_entry **p = &sn->use_gssp_proc;

        sn->use_gss_proxy = -1;
        *p = proc_create_data("use-gss-proxy", S_IFREG | 0600,
                              sn->proc_net_rpc,
                              &use_gss_proxy_proc_ops, net);
        if (!*p)
                return -ENOMEM;
        init_gssp_clnt(sn);
        return 0;
}

static void destroy_use_gss_proxy_proc_entry(struct net *net)
{
        struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);

        if (sn->use_gssp_proc) {
                remove_proc_entry("use-gss-proxy", sn->proc_net_rpc);
                clear_gssp_clnt(sn);
        }
}

static ssize_t read_gss_krb5_enctypes(struct file *file, char __user *buf,
                                      size_t count, loff_t *ppos)
{
        struct rpcsec_gss_oid oid = {
                .len    = 9,
                .data   = "\x2a\x86\x48\x86\xf7\x12\x01\x02\x02",
        };
        struct gss_api_mech *mech;
        ssize_t ret;

        mech = gss_mech_get_by_OID(&oid);
        if (!mech)
                return 0;
        if (!mech->gm_upcall_enctypes) {
                gss_mech_put(mech);
                return 0;
        }

        ret = simple_read_from_buffer(buf, count, ppos,
                                      mech->gm_upcall_enctypes,
                                      strlen(mech->gm_upcall_enctypes));
        gss_mech_put(mech);
        return ret;
}

static const struct proc_ops gss_krb5_enctypes_proc_ops = {
        .proc_open      = nonseekable_open,
        .proc_read      = read_gss_krb5_enctypes,
};

static int create_krb5_enctypes_proc_entry(struct net *net)
{
        struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);

        sn->gss_krb5_enctypes =
                proc_create_data("gss_krb5_enctypes", S_IFREG | 0444,
                                 sn->proc_net_rpc, &gss_krb5_enctypes_proc_ops,
                                 net);
        return sn->gss_krb5_enctypes ? 0 : -ENOMEM;
}

static void destroy_krb5_enctypes_proc_entry(struct net *net)
{
        struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);

        if (sn->gss_krb5_enctypes)
                remove_proc_entry("gss_krb5_enctypes", sn->proc_net_rpc);
}

#else /* CONFIG_PROC_FS */

static int create_use_gss_proxy_proc_entry(struct net *net)
{
        return 0;
}

static void destroy_use_gss_proxy_proc_entry(struct net *net) {}

static int create_krb5_enctypes_proc_entry(struct net *net)
{
        return 0;
}

static void destroy_krb5_enctypes_proc_entry(struct net *net) {}

#endif /* CONFIG_PROC_FS */

/*
 * The Call's credential body should contain a struct rpc_gss_cred_t.
 *
 * RFC 2203 Section 5
 *
 *      struct rpc_gss_cred_t {
 *              union switch (unsigned int version) {
 *              case RPCSEC_GSS_VERS_1:
 *                      struct {
 *                              rpc_gss_proc_t gss_proc;
 *                              unsigned int seq_num;
 *                              rpc_gss_service_t service;
 *                              opaque handle<>;
 *                      } rpc_gss_cred_vers_1_t;
 *              }
 *      };
 */
static bool
svcauth_gss_decode_credbody(struct xdr_stream *xdr,
                            struct rpc_gss_wire_cred *gc,
                            __be32 **rpcstart)
{
        ssize_t handle_len;
        u32 body_len;
        __be32 *p;

        p = xdr_inline_decode(xdr, XDR_UNIT);
        if (!p)
                return false;
        /*
         * start of rpc packet is 7 u32's back from here:
         * xid direction rpcversion prog vers proc flavour
         */
        *rpcstart = p - 7;
        body_len = be32_to_cpup(p);
        if (body_len > RPC_MAX_AUTH_SIZE)
                return false;

        /* struct rpc_gss_cred_t */
        if (xdr_stream_decode_u32(xdr, &gc->gc_v) < 0)
                return false;
        if (xdr_stream_decode_u32(xdr, &gc->gc_proc) < 0)
                return false;
        if (xdr_stream_decode_u32(xdr, &gc->gc_seq) < 0)
                return false;
        if (xdr_stream_decode_u32(xdr, &gc->gc_svc) < 0)
                return false;
        handle_len = xdr_stream_decode_opaque_inline(xdr,
                                                     (void **)&gc->gc_ctx.data,
                                                     body_len);
        if (handle_len < 0)
                return false;
        if (body_len != XDR_UNIT * 5 + xdr_align_size(handle_len))
                return false;

        gc->gc_ctx.len = handle_len;
        return true;
}

/**
 * svcauth_gss_accept - Decode and validate incoming RPC_AUTH_GSS credential
 * @rqstp: RPC transaction
 *
 * Return values:
 *   %SVC_OK: Success
 *   %SVC_COMPLETE: GSS context lifetime event
 *   %SVC_DENIED: Credential or verifier is not valid
 *   %SVC_GARBAGE: Failed to decode credential or verifier
 *   %SVC_CLOSE: Temporary failure
 *
 * The rqstp->rq_auth_stat field is also set (see RFCs 2203 and 5531).
 */
static enum svc_auth_status
svcauth_gss_accept(struct svc_rqst *rqstp)
{
        struct gss_svc_data *svcdata = rqstp->rq_auth_data;
        __be32          *rpcstart;
        struct rpc_gss_wire_cred *gc;
        struct rsc      *rsci = NULL;
        int             ret;
        struct sunrpc_net *sn = net_generic(SVC_NET(rqstp), sunrpc_net_id);

        rqstp->rq_auth_stat = rpc_autherr_failed;
        if (!svcdata)
                svcdata = kmalloc_obj(*svcdata);
        if (!svcdata)
                goto auth_err;
        rqstp->rq_auth_data = svcdata;
        svcdata->gsd_databody_offset = 0;
        svcdata->rsci = NULL;
        gc = &svcdata->clcred;

        rqstp->rq_auth_stat = rpc_autherr_badcred;
        if (!svcauth_gss_decode_credbody(&rqstp->rq_arg_stream, gc, &rpcstart))
                goto auth_err;
        if (gc->gc_v != RPC_GSS_VERSION)
                goto auth_err;

        switch (gc->gc_proc) {
        case RPC_GSS_PROC_INIT:
        case RPC_GSS_PROC_CONTINUE_INIT:
                if (rqstp->rq_proc != 0)
                        goto auth_err;
                return svcauth_gss_proc_init(rqstp, gc);
        case RPC_GSS_PROC_DESTROY:
                if (rqstp->rq_proc != 0)
                        goto auth_err;
                fallthrough;
        case RPC_GSS_PROC_DATA:
                rqstp->rq_auth_stat = rpcsec_gsserr_credproblem;
                rsci = gss_svc_searchbyctx(sn->rsc_cache, &gc->gc_ctx);
                if (!rsci)
                        goto auth_err;
                switch (svcauth_gss_verify_header(rqstp, rsci, rpcstart, gc)) {
                case SVC_OK:
                        break;
                case SVC_DENIED:
                        goto auth_err;
                case SVC_DROP:
                        goto drop;
                }
                break;
        default:
                if (rqstp->rq_proc != 0)
                        goto auth_err;
                rqstp->rq_auth_stat = rpc_autherr_rejectedcred;
                goto auth_err;
        }

        /* now act upon the command: */
        switch (gc->gc_proc) {
        case RPC_GSS_PROC_DESTROY:
                if (!svcauth_gss_encode_verf(rqstp, rsci->mechctx, gc->gc_seq))
                        goto auth_err;
                if (!svcxdr_set_accept_stat(rqstp))
                        goto auth_err;
                /* Delete the entry from the cache_list and call cache_put */
                sunrpc_cache_unhash(sn->rsc_cache, &rsci->h);
                goto complete;
        case RPC_GSS_PROC_DATA:
                rqstp->rq_auth_stat = rpcsec_gsserr_ctxproblem;
                if (!svcauth_gss_encode_verf(rqstp, rsci->mechctx, gc->gc_seq))
                        goto auth_err;
                if (!svcxdr_set_accept_stat(rqstp))
                        goto auth_err;
                svcdata->gsd_databody_offset = xdr_stream_pos(&rqstp->rq_res_stream);
                rqstp->rq_cred = rsci->cred;
                get_group_info(rsci->cred.cr_group_info);
                rqstp->rq_auth_stat = rpc_autherr_badcred;
                switch (gc->gc_svc) {
                case RPC_GSS_SVC_NONE:
                        break;
                case RPC_GSS_SVC_INTEGRITY:
                        /* placeholders for body length and seq. number: */
                        xdr_reserve_space(&rqstp->rq_res_stream, XDR_UNIT * 2);
                        if (svcauth_gss_unwrap_integ(rqstp, gc->gc_seq,
                                                     rsci->mechctx))
                                goto garbage_args;
                        svcxdr_set_auth_slack(rqstp, RPC_MAX_AUTH_SIZE);
                        break;
                case RPC_GSS_SVC_PRIVACY:
                        /* placeholders for body length and seq. number: */
                        xdr_reserve_space(&rqstp->rq_res_stream, XDR_UNIT * 2);
                        if (svcauth_gss_unwrap_priv(rqstp, gc->gc_seq,
                                                    rsci->mechctx))
                                goto garbage_args;
                        svcxdr_set_auth_slack(rqstp, RPC_MAX_AUTH_SIZE * 2);
                        break;
                default:
                        goto auth_err;
                }
                svcdata->rsci = rsci;
                cache_get(&rsci->h);
                rqstp->rq_cred.cr_flavor = gss_svc_to_pseudoflavor(
                                        rsci->mechctx->mech_type,
                                        GSS_C_QOP_DEFAULT,
                                        gc->gc_svc);
                ret = SVC_OK;
                trace_rpcgss_svc_authenticate(rqstp, gc);
                goto out;
        }
garbage_args:
        ret = SVC_GARBAGE;
        goto out;
auth_err:
        xdr_truncate_encode(&rqstp->rq_res_stream, XDR_UNIT * 2);
        ret = SVC_DENIED;
        goto out;
complete:
        ret = SVC_COMPLETE;
        goto out;
drop:
        ret = SVC_CLOSE;
out:
        if (rsci)
                cache_put(&rsci->h, sn->rsc_cache);
        return ret;
}

static u32
svcauth_gss_prepare_to_wrap(struct svc_rqst *rqstp, struct gss_svc_data *gsd)
{
        u32 offset;

        /* Release can be called twice, but we only wrap once. */
        offset = gsd->gsd_databody_offset;
        gsd->gsd_databody_offset = 0;

        /* AUTH_ERROR replies are not wrapped. */
        if (rqstp->rq_auth_stat != rpc_auth_ok)
                return 0;

        /* Also don't wrap if the accept_stat is nonzero: */
        if (*rqstp->rq_accept_statp != rpc_success)
                return 0;

        return offset;
}

/*
 * RFC 2203, Section 5.3.2.2
 *
 *      struct rpc_gss_integ_data {
 *              opaque databody_integ<>;
 *              opaque checksum<>;
 *      };
 *
 *      struct rpc_gss_data_t {
 *              unsigned int seq_num;
 *              proc_req_arg_t arg;
 *      };
 *
 * The RPC Reply message has already been XDR-encoded. rq_res_stream
 * is now positioned so that the checksum can be written just past
 * the RPC Reply message.
 */
static int svcauth_gss_wrap_integ(struct svc_rqst *rqstp)
{
        struct gss_svc_data *gsd = rqstp->rq_auth_data;
        struct xdr_stream *xdr = &rqstp->rq_res_stream;
        struct rpc_gss_wire_cred *gc = &gsd->clcred;
        struct xdr_buf *buf = xdr->buf;
        struct xdr_buf databody_integ;
        struct xdr_netobj checksum;
        u32 offset, maj_stat;

        offset = svcauth_gss_prepare_to_wrap(rqstp, gsd);
        if (!offset)
                goto out;

        if (xdr_buf_subsegment(buf, &databody_integ, offset + XDR_UNIT,
                               buf->len - offset - XDR_UNIT))
                goto wrap_failed;
        /* Buffer space for these has already been reserved in
         * svcauth_gss_accept(). */
        if (xdr_encode_word(buf, offset, databody_integ.len))
                goto wrap_failed;
        if (xdr_encode_word(buf, offset + XDR_UNIT, gc->gc_seq))
                goto wrap_failed;

        checksum.data = gsd->gsd_scratch;
        maj_stat = gss_get_mic(gsd->rsci->mechctx, &databody_integ, &checksum);
        if (maj_stat != GSS_S_COMPLETE)
                goto bad_mic;

        if (xdr_stream_encode_opaque(xdr, checksum.data, checksum.len) < 0)
                goto wrap_failed;
        xdr_commit_encode(xdr);

out:
        return 0;

bad_mic:
        trace_rpcgss_svc_get_mic(rqstp, maj_stat);
        return -EINVAL;
wrap_failed:
        trace_rpcgss_svc_wrap_failed(rqstp);
        return -EINVAL;
}

/*
 * RFC 2203, Section 5.3.2.3
 *
 *      struct rpc_gss_priv_data {
 *              opaque databody_priv<>
 *      };
 *
 *      struct rpc_gss_data_t {
 *              unsigned int seq_num;
 *              proc_req_arg_t arg;
 *      };
 *
 * gss_wrap() expands the size of the RPC message payload in the
 * response buffer. The main purpose of svcauth_gss_wrap_priv()
 * is to ensure there is adequate space in the response buffer to
 * avoid overflow during the wrap.
 */
static int svcauth_gss_wrap_priv(struct svc_rqst *rqstp)
{
        struct gss_svc_data *gsd = rqstp->rq_auth_data;
        struct rpc_gss_wire_cred *gc = &gsd->clcred;
        struct xdr_buf *buf = &rqstp->rq_res;
        struct kvec *head = buf->head;
        struct kvec *tail = buf->tail;
        u32 offset, pad, maj_stat;
        __be32 *p;

        offset = svcauth_gss_prepare_to_wrap(rqstp, gsd);
        if (!offset)
                return 0;

        /*
         * Buffer space for this field has already been reserved
         * in svcauth_gss_accept(). Note that the GSS sequence
         * number is encrypted along with the RPC reply payload.
         */
        if (xdr_encode_word(buf, offset + XDR_UNIT, gc->gc_seq))
                goto wrap_failed;

        /*
         * If there is currently tail data, make sure there is
         * room for the head, tail, and 2 * RPC_MAX_AUTH_SIZE in
         * the page, and move the current tail data such that
         * there is RPC_MAX_AUTH_SIZE slack space available in
         * both the head and tail.
         */
        if (tail->iov_base) {
                if (tail->iov_base >= head->iov_base + PAGE_SIZE)
                        goto wrap_failed;
                if (tail->iov_base < head->iov_base)
                        goto wrap_failed;
                if (tail->iov_len + head->iov_len
                                + 2 * RPC_MAX_AUTH_SIZE > PAGE_SIZE)
                        goto wrap_failed;
                memmove(tail->iov_base + RPC_MAX_AUTH_SIZE, tail->iov_base,
                        tail->iov_len);
                tail->iov_base += RPC_MAX_AUTH_SIZE;
        }
        /*
         * If there is no current tail data, make sure there is
         * room for the head data, and 2 * RPC_MAX_AUTH_SIZE in the
         * allotted page, and set up tail information such that there
         * is RPC_MAX_AUTH_SIZE slack space available in both the
         * head and tail.
         */
        if (!tail->iov_base) {
                if (head->iov_len + 2 * RPC_MAX_AUTH_SIZE > PAGE_SIZE)
                        goto wrap_failed;
                tail->iov_base = head->iov_base
                        + head->iov_len + RPC_MAX_AUTH_SIZE;
                tail->iov_len = 0;
        }

        maj_stat = gss_wrap(gsd->rsci->mechctx, offset + XDR_UNIT, buf,
                            buf->pages);
        if (maj_stat != GSS_S_COMPLETE)
                goto bad_wrap;

        /* Wrapping can change the size of databody_priv. */
        if (xdr_encode_word(buf, offset, buf->len - offset - XDR_UNIT))
                goto wrap_failed;
        pad = xdr_pad_size(buf->len - offset - XDR_UNIT);
        p = (__be32 *)(tail->iov_base + tail->iov_len);
        memset(p, 0, pad);
        tail->iov_len += pad;
        buf->len += pad;

        return 0;
wrap_failed:
        trace_rpcgss_svc_wrap_failed(rqstp);
        return -EINVAL;
bad_wrap:
        trace_rpcgss_svc_wrap(rqstp, maj_stat);
        return -ENOMEM;
}

/**
 * svcauth_gss_release - Wrap payload and release resources
 * @rqstp: RPC transaction context
 *
 * Return values:
 *    %0: the Reply is ready to be sent
 *    %-ENOMEM: failed to allocate memory
 *    %-EINVAL: encoding error
 */
static int
svcauth_gss_release(struct svc_rqst *rqstp)
{
        struct sunrpc_net *sn = net_generic(SVC_NET(rqstp), sunrpc_net_id);
        struct gss_svc_data *gsd = rqstp->rq_auth_data;
        struct rpc_gss_wire_cred *gc;
        int stat;

        if (!gsd)
                goto out;
        gc = &gsd->clcred;
        if (gc->gc_proc != RPC_GSS_PROC_DATA)
                goto out;

        switch (gc->gc_svc) {
        case RPC_GSS_SVC_NONE:
                break;
        case RPC_GSS_SVC_INTEGRITY:
                stat = svcauth_gss_wrap_integ(rqstp);
                if (stat)
                        goto out_err;
                break;
        case RPC_GSS_SVC_PRIVACY:
                stat = svcauth_gss_wrap_priv(rqstp);
                if (stat)
                        goto out_err;
                break;
        /*
         * For any other gc_svc value, svcauth_gss_accept() already set
         * the auth_error appropriately; just fall through:
         */
        }

out:
        stat = 0;
out_err:
        if (rqstp->rq_client)
                auth_domain_put(rqstp->rq_client);
        rqstp->rq_client = NULL;
        if (rqstp->rq_gssclient)
                auth_domain_put(rqstp->rq_gssclient);
        rqstp->rq_gssclient = NULL;
        if (rqstp->rq_cred.cr_group_info)
                put_group_info(rqstp->rq_cred.cr_group_info);
        rqstp->rq_cred.cr_group_info = NULL;
        if (gsd && gsd->rsci) {
                cache_put(&gsd->rsci->h, sn->rsc_cache);
                gsd->rsci = NULL;
        }
        return stat;
}

static void
svcauth_gss_domain_release_rcu(struct rcu_head *head)
{
        struct auth_domain *dom = container_of(head, struct auth_domain, rcu_head);
        struct gss_domain *gd = container_of(dom, struct gss_domain, h);

        kfree(dom->name);
        kfree(gd);
}

static void
svcauth_gss_domain_release(struct auth_domain *dom)
{
        call_rcu(&dom->rcu_head, svcauth_gss_domain_release_rcu);
}

static rpc_authflavor_t svcauth_gss_pseudoflavor(struct svc_rqst *rqstp)
{
        return svcauth_gss_flavor(rqstp->rq_gssclient);
}

static struct auth_ops svcauthops_gss = {
        .name           = "rpcsec_gss",
        .owner          = THIS_MODULE,
        .flavour        = RPC_AUTH_GSS,
        .accept         = svcauth_gss_accept,
        .release        = svcauth_gss_release,
        .domain_release = svcauth_gss_domain_release,
        .set_client     = svcauth_gss_set_client,
        .pseudoflavor   = svcauth_gss_pseudoflavor,
};

static int rsi_cache_create_net(struct net *net)
{
        struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
        struct cache_detail *cd;
        int err;

        cd = cache_create_net(&rsi_cache_template, net);
        if (IS_ERR(cd))
                return PTR_ERR(cd);
        err = cache_register_net(cd, net);
        if (err) {
                cache_destroy_net(cd, net);
                return err;
        }
        sn->rsi_cache = cd;
        return 0;
}

static void rsi_cache_destroy_net(struct net *net)
{
        struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
        struct cache_detail *cd = sn->rsi_cache;

        sn->rsi_cache = NULL;
        cache_purge(cd);
        cache_unregister_net(cd, net);
        cache_destroy_net(cd, net);
}

static int rsc_cache_create_net(struct net *net)
{
        struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
        struct cache_detail *cd;
        int err;

        cd = cache_create_net(&rsc_cache_template, net);
        if (IS_ERR(cd))
                return PTR_ERR(cd);
        err = cache_register_net(cd, net);
        if (err) {
                cache_destroy_net(cd, net);
                return err;
        }
        sn->rsc_cache = cd;
        return 0;
}

static void rsc_cache_destroy_net(struct net *net)
{
        struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
        struct cache_detail *cd = sn->rsc_cache;

        sn->rsc_cache = NULL;
        cache_purge(cd);
        cache_unregister_net(cd, net);
        cache_destroy_net(cd, net);
}

int
gss_svc_init_net(struct net *net)
{
        int rv;

        rv = rsc_cache_create_net(net);
        if (rv)
                return rv;
        rv = rsi_cache_create_net(net);
        if (rv)
                goto out1;
        rv = create_use_gss_proxy_proc_entry(net);
        if (rv)
                goto out2;

        rv = create_krb5_enctypes_proc_entry(net);
        if (rv)
                goto out3;

        return 0;

out3:
        destroy_use_gss_proxy_proc_entry(net);
out2:
        rsi_cache_destroy_net(net);
out1:
        rsc_cache_destroy_net(net);
        return rv;
}

void
gss_svc_shutdown_net(struct net *net)
{
        destroy_krb5_enctypes_proc_entry(net);
        destroy_use_gss_proxy_proc_entry(net);
        rsi_cache_destroy_net(net);
        rsc_cache_destroy_net(net);
}

int
gss_svc_init(void)
{
        return svc_auth_register(RPC_AUTH_GSS, &svcauthops_gss);
}

void
gss_svc_shutdown(void)
{
        svc_auth_unregister(RPC_AUTH_GSS);
}