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svcauth_gss.c

/*
 * 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/types.h>
#include <linux/module.h>
#include <linux/pagemap.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>

#ifdef RPC_DEBUG
# define RPCDBG_FACILITY      RPCDBG_AUTH
#endif

/* 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)
#define     RSI_HASHMASK      (RSI_HASHMAX-1)

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;
};

static struct cache_head *rsi_table[RSI_HASHMAX];
static struct cache_detail rsi_cache;
static struct rsi *rsi_update(struct rsi *new, struct rsi *old);
static struct rsi *rsi_lookup(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_put(struct kref *ref)
{
      struct rsi *rsii = container_of(ref, struct rsi, h.ref);
      rsi_free(rsii);
      kfree(rsii);
}

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(sizeof(*rsii), GFP_KERNEL);
      if (rsii)
            return &rsii->h;
      else
            return NULL;
}

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';
}


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;
      time_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(&rsii);
      if (!rsip)
            goto out;

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

      /* major/minor */
      len = qword_get(&mesg, buf, mlen);
      if (len < 0)
            goto out;
      if (len == 0) {
            goto out;
      } else {
            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(&rsii, rsip);
      status = 0;
out:
      rsi_free(&rsii);
      if (rsip)
            cache_put(&rsip->h, &rsi_cache);
      else
            status = -ENOMEM;
      return status;
}

static struct cache_detail rsi_cache = {
      .owner            = THIS_MODULE,
      .hash_size  = RSI_HASHMAX,
      .hash_table     = rsi_table,
      .name           = "auth.rpcsec.init",
      .cache_put      = rsi_put,
      .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 rsi *item)
{
      struct cache_head *ch;
      int hash = rsi_hash(item);

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

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

      ch = sunrpc_cache_update(&rsi_cache, &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     RSC_HASHMASK      (RSC_HASHMAX-1)

#define GSS_SEQ_WIN     128

struct gss_svc_seq_data {
      /* highest seq number seen so far: */
      int               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;
};

static struct cache_head *rsc_table[RSC_HASHMAX];
static struct cache_detail rsc_cache;
static struct rsc *rsc_update(struct rsc *new, struct rsc *old);
static struct rsc *rsc_lookup(struct rsc *item);

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

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

      rsc_free(rsci);
      kfree(rsci);
}

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;
      new->cred.cr_group_info = NULL;
}

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;
      tmp->cred.cr_group_info = NULL;
}

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

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 len, rv;
      struct rsc rsci, *rscp = NULL;
      time_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 */
      expiry = get_expiry(&mesg);
      status = -EINVAL;
      if (expiry == 0)
            goto out;

      rscp = rsc_lookup(&rsci);
      if (!rscp)
            goto out;

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

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

            /* number of additional gid's */
            if (get_int(&mesg, &N))
                  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++) {
                  gid_t gid;
                  if (get_int(&mesg, &gid))
                        goto out;
                  GROUP_AT(rsci.cred.cr_group_info, i) = gid;
            }

            /* mech name */
            len = qword_get(&mesg, buf, mlen);
            if (len < 0)
                  goto out;
            gm = 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);
            if (status)
                  goto out;
      }
      rsci.h.expiry_time = expiry;
      rscp = rsc_update(&rsci, rscp);
      status = 0;
out:
      gss_mech_put(gm);
      rsc_free(&rsci);
      if (rscp)
            cache_put(&rscp->h, &rsc_cache);
      else
            status = -ENOMEM;
      return status;
}

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

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

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

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

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


static struct rsc *
gss_svc_searchbyctx(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(&rsci);
      rsc_free(&rsci);
      if (!found)
            return NULL;
      if (cache_check(&rsc_cache, &found->h, NULL))
            return NULL;
      return found;
}

/* Implements sequence number algorithm as specified in RFC 2203. */
static int
gss_check_seq_num(struct rsc *rsci, int seq_num)
{
      struct gss_svc_seq_data *sd = &rsci->seqdata;

      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 <= sd->sd_max - GSS_SEQ_WIN) {
            goto drop;
      }
      /* sd_max - GSS_SEQ_WIN < seq_num <= sd_max */
      if (__test_and_set_bit(seq_num % GSS_SEQ_WIN, sd->sd_win))
            goto drop;
ok:
      spin_unlock(&sd->sd_lock);
      return 1;
drop:
      spin_unlock(&sd->sd_lock);
      return 0;
}

static inline u32 round_up_to_quad(u32 i)
{
      return (i + 3 ) & ~3;
}

static inline int
svc_safe_getnetobj(struct kvec *argv, struct xdr_netobj *o)
{
      int l;

      if (argv->iov_len < 4)
            return -1;
      o->len = svc_getnl(argv);
      l = round_up_to_quad(o->len);
      if (argv->iov_len < l)
            return -1;
      o->data = argv->iov_base;
      argv->iov_base += l;
      argv->iov_len -= l;
      return 0;
}

static inline int
svc_safe_putnetobj(struct kvec *resv, struct xdr_netobj *o)
{
      u8 *p;

      if (resv->iov_len + 4 > PAGE_SIZE)
            return -1;
      svc_putnl(resv, o->len);
      p = resv->iov_base + resv->iov_len;
      resv->iov_len += round_up_to_quad(o->len);
      if (resv->iov_len > PAGE_SIZE)
            return -1;
      memcpy(p, o->data, o->len);
      memset(p + o->len, 0, round_up_to_quad(o->len) - o->len);
      return 0;
}

/*
 * Verify the checksum on the header and return SVC_OK on success.
 * Otherwise, return SVC_DROP (in the case of a bad sequence number)
 * or return SVC_DENIED and indicate error in authp.
 */
static int
gss_verify_header(struct svc_rqst *rqstp, struct rsc *rsci,
              __be32 *rpcstart, struct rpc_gss_wire_cred *gc, __be32 *authp)
{
      struct gss_ctx          *ctx_id = rsci->mechctx;
      struct xdr_buf          rpchdr;
      struct xdr_netobj checksum;
      u32               flavor = 0;
      struct kvec       *argv = &rqstp->rq_arg.head[0];
      struct kvec       iov;

      /* data to compute the checksum over: */
      iov.iov_base = rpcstart;
      iov.iov_len = (u8 *)argv->iov_base - (u8 *)rpcstart;
      xdr_buf_from_iov(&iov, &rpchdr);

      *authp = rpc_autherr_badverf;
      if (argv->iov_len < 4)
            return SVC_DENIED;
      flavor = svc_getnl(argv);
      if (flavor != RPC_AUTH_GSS)
            return SVC_DENIED;
      if (svc_safe_getnetobj(argv, &checksum))
            return SVC_DENIED;

      if (rqstp->rq_deferred) /* skip verification of revisited request */
            return SVC_OK;
      if (gss_verify_mic(ctx_id, &rpchdr, &checksum) != GSS_S_COMPLETE) {
            *authp = rpcsec_gsserr_credproblem;
            return SVC_DENIED;
      }

      if (gc->gc_seq > MAXSEQ) {
            dprintk("RPC:       svcauth_gss: discarding request with "
                        "large sequence number %d\n", gc->gc_seq);
            *authp = rpcsec_gsserr_ctxproblem;
            return SVC_DENIED;
      }
      if (!gss_check_seq_num(rsci, gc->gc_seq)) {
            dprintk("RPC:       svcauth_gss: discarding request with "
                        "old sequence number %d\n", gc->gc_seq);
            return SVC_DROP;
      }
      return SVC_OK;
}

static int
gss_write_null_verf(struct svc_rqst *rqstp)
{
      __be32     *p;

      svc_putnl(rqstp->rq_res.head, RPC_AUTH_NULL);
      p = rqstp->rq_res.head->iov_base + rqstp->rq_res.head->iov_len;
      /* don't really need to check if head->iov_len > PAGE_SIZE ... */
      *p++ = 0;
      if (!xdr_ressize_check(rqstp, p))
            return -1;
      return 0;
}

static int
gss_write_verf(struct svc_rqst *rqstp, struct gss_ctx *ctx_id, u32 seq)
{
      __be32                  xdr_seq;
      u32               maj_stat;
      struct xdr_buf          verf_data;
      struct xdr_netobj mic;
      __be32                  *p;
      struct kvec       iov;

      svc_putnl(rqstp->rq_res.head, RPC_AUTH_GSS);
      xdr_seq = htonl(seq);

      iov.iov_base = &xdr_seq;
      iov.iov_len = sizeof(xdr_seq);
      xdr_buf_from_iov(&iov, &verf_data);
      p = rqstp->rq_res.head->iov_base + rqstp->rq_res.head->iov_len;
      mic.data = (u8 *)(p + 1);
      maj_stat = gss_get_mic(ctx_id, &verf_data, &mic);
      if (maj_stat != GSS_S_COMPLETE)
            return -1;
      *p++ = htonl(mic.len);
      memset((u8 *)p + mic.len, 0, round_up_to_quad(mic.len) - mic.len);
      p += XDR_QUADLEN(mic.len);
      if (!xdr_ressize_check(rqstp, p))
            return -1;
      return 0;
}

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(svcauth_gss_flavor);

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

      new = kmalloc(sizeof(*new), GFP_KERNEL);
      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;

      stat = 0;
      test = auth_domain_lookup(name, &new->h);
      if (test != &new->h) { /* Duplicate registration */
            auth_domain_put(test);
            kfree(new->h.name);
            goto out_free_dom;
      }
      return 0;

out_free_dom:
      kfree(new);
out:
      return stat;
}

EXPORT_SYMBOL(svcauth_gss_register_pseudoflavor);

static inline int
read_u32_from_xdr_buf(struct xdr_buf *buf, int base, u32 *obj)
{
      __be32  raw;
      int     status;

      status = read_bytes_from_xdr_buf(buf, base, &raw, sizeof(*obj));
      if (status)
            return status;
      *obj = ntohl(raw);
      return 0;
}

/* It would be nice if this bit of code could be shared with the client.
 * Obstacles:
 *    The client shouldn't malloc(), would have to pass in own memory.
 *    The server uses base of head iovec as read pointer, while the
 *    client uses separate pointer. */
static int
unwrap_integ_data(struct xdr_buf *buf, u32 seq, struct gss_ctx *ctx)
{
      int stat = -EINVAL;
      u32 integ_len, maj_stat;
      struct xdr_netobj mic;
      struct xdr_buf integ_buf;

      integ_len = svc_getnl(&buf->head[0]);
      if (integ_len & 3)
            return stat;
      if (integ_len > buf->len)
            return stat;
      if (xdr_buf_subsegment(buf, &integ_buf, 0, integ_len))
            BUG();
      /* copy out mic... */
      if (read_u32_from_xdr_buf(buf, integ_len, &mic.len))
            BUG();
      if (mic.len > RPC_MAX_AUTH_SIZE)
            return stat;
      mic.data = kmalloc(mic.len, GFP_KERNEL);
      if (!mic.data)
            return stat;
      if (read_bytes_from_xdr_buf(buf, integ_len + 4, mic.data, mic.len))
            goto out;
      maj_stat = gss_verify_mic(ctx, &integ_buf, &mic);
      if (maj_stat != GSS_S_COMPLETE)
            goto out;
      if (svc_getnl(&buf->head[0]) != seq)
            goto out;
      stat = 0;
out:
      kfree(mic.data);
      return stat;
}

static inline int
total_buf_len(struct xdr_buf *buf)
{
      return buf->head[0].iov_len + buf->page_len + buf->tail[0].iov_len;
}

static void
fix_priv_head(struct xdr_buf *buf, int pad)
{
      if (buf->page_len == 0) {
            /* We need to adjust head and buf->len in tandem in this
             * case to make svc_defer() work--it finds the original
             * buffer start using buf->len - buf->head[0].iov_len. */
            buf->head[0].iov_len -= pad;
      }
}

static int
unwrap_priv_data(struct svc_rqst *rqstp, struct xdr_buf *buf, u32 seq, struct gss_ctx *ctx)
{
      u32 priv_len, maj_stat;
      int pad, saved_len, remaining_len, offset;

      rqstp->rq_splice_ok = 0;

      priv_len = svc_getnl(&buf->head[0]);
      if (rqstp->rq_deferred) {
            /* Already decrypted last time through! The sequence number
             * check at out_seq is unnecessary but harmless: */
            goto out_seq;
      }
      /* buf->len is the number of bytes from the original start of the
       * request to the end, where head[0].iov_len is just the bytes
       * not yet read from the head, so these two values are different: */
      remaining_len = total_buf_len(buf);
      if (priv_len > remaining_len)
            return -EINVAL;
      pad = remaining_len - priv_len;
      buf->len -= pad;
      fix_priv_head(buf, pad);

      /* Maybe it would be better to give gss_unwrap a length parameter: */
      saved_len = buf->len;
      buf->len = priv_len;
      maj_stat = gss_unwrap(ctx, 0, buf);
      pad = priv_len - buf->len;
      buf->len = saved_len;
      buf->len -= pad;
      /* The upper layers assume the buffer is aligned on 4-byte boundaries.
       * In the krb5p case, at least, the data ends up offset, so we need to
       * move it around. */
      /* XXX: This is very inefficient.  It would be better to either do
       * this while we encrypt, or maybe in the receive code, if we can peak
       * ahead and work out the service and mechanism there. */
      offset = buf->head[0].iov_len % 4;
      if (offset) {
            buf->buflen = RPCSVC_MAXPAYLOAD;
            xdr_shift_buf(buf, offset);
            fix_priv_head(buf, pad);
      }
      if (maj_stat != GSS_S_COMPLETE)
            return -EINVAL;
out_seq:
      if (svc_getnl(&buf->head[0]) != seq)
            return -EINVAL;
      return 0;
}

struct gss_svc_data {
      /* decoded gss client cred: */
      struct rpc_gss_wire_cred      clcred;
      /* save a pointer to the beginning of the encoded verifier,
       * for use in encryption/checksumming in svcauth_gss_release: */
      __be32                        *verf_start;
      struct rsc              *rsci;
};

static int
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;

      /*
       * 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)
            return stat;
      return SVC_OK;
}

static inline int
gss_write_init_verf(struct svc_rqst *rqstp, struct rsi *rsip)
{
      struct rsc *rsci;
      int        rc;

      if (rsip->major_status != GSS_S_COMPLETE)
            return gss_write_null_verf(rqstp);
      rsci = gss_svc_searchbyctx(&rsip->out_handle);
      if (rsci == NULL) {
            rsip->major_status = GSS_S_NO_CONTEXT;
            return gss_write_null_verf(rqstp);
      }
      rc = gss_write_verf(rqstp, rsci->mechctx, GSS_SEQ_WIN);
      cache_put(&rsci->h, &rsc_cache);
      return rc;
}

/*
 * 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_handle_init(struct svc_rqst *rqstp,
                  struct rpc_gss_wire_cred *gc, __be32 *authp)
{
      struct kvec *argv = &rqstp->rq_arg.head[0];
      struct kvec *resv = &rqstp->rq_res.head[0];
      struct xdr_netobj tmpobj;
      struct rsi *rsip, rsikey;

      /* Read the verifier; should be NULL: */
      *authp = rpc_autherr_badverf;
      if (argv->iov_len < 2 * 4)
            return SVC_DENIED;
      if (svc_getnl(argv) != RPC_AUTH_NULL)
            return SVC_DENIED;
      if (svc_getnl(argv) != 0)
            return SVC_DENIED;

      /* Martial context handle and token for upcall: */
      *authp = rpc_autherr_badcred;
      if (gc->gc_proc == RPC_GSS_PROC_INIT && gc->gc_ctx.len != 0)
            return SVC_DENIED;
      memset(&rsikey, 0, sizeof(rsikey));
      if (dup_netobj(&rsikey.in_handle, &gc->gc_ctx))
            return SVC_DROP;
      *authp = rpc_autherr_badverf;
      if (svc_safe_getnetobj(argv, &tmpobj)) {
            kfree(rsikey.in_handle.data);
            return SVC_DENIED;
      }
      if (dup_netobj(&rsikey.in_token, &tmpobj)) {
            kfree(rsikey.in_handle.data);
            return SVC_DROP;
      }

      /* Perform upcall, or find upcall result: */
      rsip = rsi_lookup(&rsikey);
      rsi_free(&rsikey);
      if (!rsip)
            return SVC_DROP;
      switch (cache_check(&rsi_cache, &rsip->h, &rqstp->rq_chandle)) {
      case -EAGAIN:
      case -ETIMEDOUT:
      case -ENOENT:
            /* No upcall result: */
            return SVC_DROP;
      case 0:
            /* Got an answer to the upcall; use it: */
            if (gss_write_init_verf(rqstp, rsip))
                  return SVC_DROP;
            if (resv->iov_len + 4 > PAGE_SIZE)
                  return SVC_DROP;
            svc_putnl(resv, RPC_SUCCESS);
            if (svc_safe_putnetobj(resv, &rsip->out_handle))
                  return SVC_DROP;
            if (resv->iov_len + 3 * 4 > PAGE_SIZE)
                  return SVC_DROP;
            svc_putnl(resv, rsip->major_status);
            svc_putnl(resv, rsip->minor_status);
            svc_putnl(resv, GSS_SEQ_WIN);
            if (svc_safe_putnetobj(resv, &rsip->out_token))
                  return SVC_DROP;
      }
      return SVC_COMPLETE;
}

/*
 * Accept an rpcsec packet.
 * If context establishment, punt to user space
 * If data exchange, verify/decrypt
 * If context destruction, handle here
 * In the context establishment and destruction case we encode
 * response here and return SVC_COMPLETE.
 */
static int
svcauth_gss_accept(struct svc_rqst *rqstp, __be32 *authp)
{
      struct kvec *argv = &rqstp->rq_arg.head[0];
      struct kvec *resv = &rqstp->rq_res.head[0];
      u32         crlen;
      struct gss_svc_data *svcdata = rqstp->rq_auth_data;
      struct rpc_gss_wire_cred *gc;
      struct rsc  *rsci = NULL;
      __be32            *rpcstart;
      __be32            *reject_stat = resv->iov_base + resv->iov_len;
      int         ret;

      dprintk("RPC:       svcauth_gss: argv->iov_len = %zd\n",
                  argv->iov_len);

      *authp = rpc_autherr_badcred;
      if (!svcdata)
            svcdata = kmalloc(sizeof(*svcdata), GFP_KERNEL);
      if (!svcdata)
            goto auth_err;
      rqstp->rq_auth_data = svcdata;
      svcdata->verf_start = NULL;
      svcdata->rsci = NULL;
      gc = &svcdata->clcred;

      /* start of rpc packet is 7 u32's back from here:
       * xid direction rpcversion prog vers proc flavour
       */
      rpcstart = argv->iov_base;
      rpcstart -= 7;

      /* credential is:
       *   version(==1), proc(0,1,2,3), seq, service (1,2,3), handle
       * at least 5 u32s, and is preceeded by length, so that makes 6.
       */

      if (argv->iov_len < 5 * 4)
            goto auth_err;
      crlen = svc_getnl(argv);
      if (svc_getnl(argv) != RPC_GSS_VERSION)
            goto auth_err;
      gc->gc_proc = svc_getnl(argv);
      gc->gc_seq = svc_getnl(argv);
      gc->gc_svc = svc_getnl(argv);
      if (svc_safe_getnetobj(argv, &gc->gc_ctx))
            goto auth_err;
      if (crlen != round_up_to_quad(gc->gc_ctx.len) + 5 * 4)
            goto auth_err;

      if ((gc->gc_proc != RPC_GSS_PROC_DATA) && (rqstp->rq_proc != 0))
            goto auth_err;

      *authp = rpc_autherr_badverf;
      switch (gc->gc_proc) {
      case RPC_GSS_PROC_INIT:
      case RPC_GSS_PROC_CONTINUE_INIT:
            return svcauth_gss_handle_init(rqstp, gc, authp);
      case RPC_GSS_PROC_DATA:
      case RPC_GSS_PROC_DESTROY:
            /* Look up the context, and check the verifier: */
            *authp = rpcsec_gsserr_credproblem;
            rsci = gss_svc_searchbyctx(&gc->gc_ctx);
            if (!rsci)
                  goto auth_err;
            switch (gss_verify_header(rqstp, rsci, rpcstart, gc, authp)) {
            case SVC_OK:
                  break;
            case SVC_DENIED:
                  goto auth_err;
            case SVC_DROP:
                  goto drop;
            }
            break;
      default:
            *authp = rpc_autherr_rejectedcred;
            goto auth_err;
      }

      /* now act upon the command: */
      switch (gc->gc_proc) {
      case RPC_GSS_PROC_DESTROY:
            if (gss_write_verf(rqstp, rsci->mechctx, gc->gc_seq))
                  goto auth_err;
            set_bit(CACHE_NEGATIVE, &rsci->h.flags);
            if (resv->iov_len + 4 > PAGE_SIZE)
                  goto drop;
            svc_putnl(resv, RPC_SUCCESS);
            goto complete;
      case RPC_GSS_PROC_DATA:
            *authp = rpcsec_gsserr_ctxproblem;
            svcdata->verf_start = resv->iov_base + resv->iov_len;
            if (gss_write_verf(rqstp, rsci->mechctx, gc->gc_seq))
                  goto auth_err;
            rqstp->rq_cred = rsci->cred;
            get_group_info(rsci->cred.cr_group_info);
            *authp = rpc_autherr_badcred;
            switch (gc->gc_svc) {
            case RPC_GSS_SVC_NONE:
                  break;
            case RPC_GSS_SVC_INTEGRITY:
                  if (unwrap_integ_data(&rqstp->rq_arg,
                              gc->gc_seq, rsci->mechctx))
                        goto auth_err;
                  /* placeholders for length and seq. number: */
                  svc_putnl(resv, 0);
                  svc_putnl(resv, 0);
                  break;
            case RPC_GSS_SVC_PRIVACY:
                  if (unwrap_priv_data(rqstp, &rqstp->rq_arg,
                              gc->gc_seq, rsci->mechctx))
                        goto auth_err;
                  /* placeholders for length and seq. number: */
                  svc_putnl(resv, 0);
                  svc_putnl(resv, 0);
                  break;
            default:
                  goto auth_err;
            }
            svcdata->rsci = rsci;
            cache_get(&rsci->h);
            rqstp->rq_flavor = gss_svc_to_pseudoflavor(
                              rsci->mechctx->mech_type, gc->gc_svc);
            ret = SVC_OK;
            goto out;
      }
auth_err:
      /* Restore write pointer to its original value: */
      xdr_ressize_check(rqstp, reject_stat);
      ret = SVC_DENIED;
      goto out;
complete:
      ret = SVC_COMPLETE;
      goto out;
drop:
      ret = SVC_DROP;
out:
      if (rsci)
            cache_put(&rsci->h, &rsc_cache);
      return ret;
}

static __be32 *
svcauth_gss_prepare_to_wrap(struct xdr_buf *resbuf, struct gss_svc_data *gsd)
{
      __be32 *p;
      u32 verf_len;

      p = gsd->verf_start;
      gsd->verf_start = NULL;

      /* If the reply stat is nonzero, don't wrap: */
      if (*(p-1) != rpc_success)
            return NULL;
      /* Skip the verifier: */
      p += 1;
      verf_len = ntohl(*p++);
      p += XDR_QUADLEN(verf_len);
      /* move accept_stat to right place: */
      memcpy(p, p + 2, 4);
      /* Also don't wrap if the accept stat is nonzero: */
      if (*p != rpc_success) {
            resbuf->head[0].iov_len -= 2 * 4;
            return NULL;
      }
      p++;
      return p;
}

static inline int
svcauth_gss_wrap_resp_integ(struct svc_rqst *rqstp)
{
      struct gss_svc_data *gsd = (struct gss_svc_data *)rqstp->rq_auth_data;
      struct rpc_gss_wire_cred *gc = &gsd->clcred;
      struct xdr_buf *resbuf = &rqstp->rq_res;
      struct xdr_buf integ_buf;
      struct xdr_netobj mic;
      struct kvec *resv;
      __be32 *p;
      int integ_offset, integ_len;
      int stat = -EINVAL;

      p = svcauth_gss_prepare_to_wrap(resbuf, gsd);
      if (p == NULL)
            goto out;
      integ_offset = (u8 *)(p + 1) - (u8 *)resbuf->head[0].iov_base;
      integ_len = resbuf->len - integ_offset;
      BUG_ON(integ_len % 4);
      *p++ = htonl(integ_len);
      *p++ = htonl(gc->gc_seq);
      if (xdr_buf_subsegment(resbuf, &integ_buf, integ_offset,
                        integ_len))
            BUG();
      if (resbuf->tail[0].iov_base == NULL) {
            if (resbuf->head[0].iov_len + RPC_MAX_AUTH_SIZE > PAGE_SIZE)
                  goto out_err;
            resbuf->tail[0].iov_base = resbuf->head[0].iov_base
                                    + resbuf->head[0].iov_len;
            resbuf->tail[0].iov_len = 0;
            resv = &resbuf->tail[0];
      } else {
            resv = &resbuf->tail[0];
      }
      mic.data = (u8 *)resv->iov_base + resv->iov_len + 4;
      if (gss_get_mic(gsd->rsci->mechctx, &integ_buf, &mic))
            goto out_err;
      svc_putnl(resv, mic.len);
      memset(mic.data + mic.len, 0,
                  round_up_to_quad(mic.len) - mic.len);
      resv->iov_len += XDR_QUADLEN(mic.len) << 2;
      /* not strictly required: */
      resbuf->len += XDR_QUADLEN(mic.len) << 2;
      BUG_ON(resv->iov_len > PAGE_SIZE);
out:
      stat = 0;
out_err:
      return stat;
}

static inline int
svcauth_gss_wrap_resp_priv(struct svc_rqst *rqstp)
{
      struct gss_svc_data *gsd = (struct gss_svc_data *)rqstp->rq_auth_data;
      struct rpc_gss_wire_cred *gc = &gsd->clcred;
      struct xdr_buf *resbuf = &rqstp->rq_res;
      struct page **inpages = NULL;
      __be32 *p, *len;
      int offset;
      int pad;

      p = svcauth_gss_prepare_to_wrap(resbuf, gsd);
      if (p == NULL)
            return 0;
      len = p++;
      offset = (u8 *)p - (u8 *)resbuf->head[0].iov_base;
      *p++ = htonl(gc->gc_seq);
      inpages = resbuf->pages;
      /* XXX: Would be better to write some xdr helper functions for
       * nfs{2,3,4}xdr.c that place the data right, instead of copying: */
      if (resbuf->tail[0].iov_base) {
            BUG_ON(resbuf->tail[0].iov_base >= resbuf->head[0].iov_base
                                          + PAGE_SIZE);
            BUG_ON(resbuf->tail[0].iov_base < resbuf->head[0].iov_base);
            if (resbuf->tail[0].iov_len + resbuf->head[0].iov_len
                        + 2 * RPC_MAX_AUTH_SIZE > PAGE_SIZE)
                  return -ENOMEM;
            memmove(resbuf->tail[0].iov_base + RPC_MAX_AUTH_SIZE,
                  resbuf->tail[0].iov_base,
                  resbuf->tail[0].iov_len);
            resbuf->tail[0].iov_base += RPC_MAX_AUTH_SIZE;
      }
      if (resbuf->tail[0].iov_base == NULL) {
            if (resbuf->head[0].iov_len + 2*RPC_MAX_AUTH_SIZE > PAGE_SIZE)
                  return -ENOMEM;
            resbuf->tail[0].iov_base = resbuf->head[0].iov_base
                  + resbuf->head[0].iov_len + RPC_MAX_AUTH_SIZE;
            resbuf->tail[0].iov_len = 0;
      }
      if (gss_wrap(gsd->rsci->mechctx, offset, resbuf, inpages))
            return -ENOMEM;
      *len = htonl(resbuf->len - offset);
      pad = 3 - ((resbuf->len - offset - 1)&3);
      p = (__be32 *)(resbuf->tail[0].iov_base + resbuf->tail[0].iov_len);
      memset(p, 0, pad);
      resbuf->tail[0].iov_len += pad;
      resbuf->len += pad;
      return 0;
}

static int
svcauth_gss_release(struct svc_rqst *rqstp)
{
      struct gss_svc_data *gsd = (struct gss_svc_data *)rqstp->rq_auth_data;
      struct rpc_gss_wire_cred *gc = &gsd->clcred;
      struct xdr_buf *resbuf = &rqstp->rq_res;
      int stat = -EINVAL;

      if (gc->gc_proc != RPC_GSS_PROC_DATA)
            goto out;
      /* Release can be called twice, but we only wrap once. */
      if (gsd->verf_start == NULL)
            goto out;
      /* normally not set till svc_send, but we need it here: */
      /* XXX: what for?  Do we mess it up the moment we call svc_putu32
       * or whatever? */
      resbuf->len = total_buf_len(resbuf);
      switch (gc->gc_svc) {
      case RPC_GSS_SVC_NONE:
            break;
      case RPC_GSS_SVC_INTEGRITY:
            stat = svcauth_gss_wrap_resp_integ(rqstp);
            if (stat)
                  goto out_err;
            break;
      case RPC_GSS_SVC_PRIVACY:
            stat = svcauth_gss_wrap_resp_priv(rqstp);
            if (stat)
                  goto out_err;
            break;
      default:
            goto out_err;
      }

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->rsci)
            cache_put(&gsd->rsci->h, &rsc_cache);
      gsd->rsci = NULL;

      return stat;
}

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

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

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,
};

int
gss_svc_init(void)
{
      int rv = svc_auth_register(RPC_AUTH_GSS, &svcauthops_gss);
      if (rv == 0) {
            cache_register(&rsc_cache);
            cache_register(&rsi_cache);
      }
      return rv;
}

void
gss_svc_shutdown(void)
{
      if (cache_unregister(&rsc_cache))
            printk(KERN_ERR "auth_rpcgss: failed to unregister rsc cache\n");
      if (cache_unregister(&rsi_cache))
            printk(KERN_ERR "auth_rpcgss: failed to unregister rsi cache\n");
      svc_auth_unregister(RPC_AUTH_GSS);
}

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