source: trunk/athena/lib/locker/afs.c @ 22841

/* Copyright 1998 by the Massachusetts Institute of Technology.
 *
 * Permission to use, copy, modify, and distribute this
 * software and its documentation for any purpose and without
 * fee is hereby granted, provided that the above copyright
 * notice appear in all copies and that both that copyright
 * notice and this permission notice appear in supporting
 * documentation, and that the name of M.I.T. not be used in
 * advertising or publicity pertaining to distribution of the
 * software without specific, written prior permission.
 * M.I.T. makes no representations about the suitability of
 * this software for any purpose.  It is provided "as is"
 * without express or implied warranty.
 */

/* This file is part of liblocker. It implements AFS lockers. */

static const char rcsid[] = "$Id: afs.c,v 1.16 2006-08-08 21:50:09 ghudson Exp $";

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <errno.h>
#include <netdb.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <afs/stds.h>
#include <afs/param.h>
#include <afs/auth.h>
#include <afs/cellconfig.h>
#include <afs/ptserver.h>
#include <afs/ptuser.h>
#include <afs/venus.h>
#include <rx/rxkad.h>

/* This is defined in <afs/volume.h>, but it doesn't seem possible to
 * include that without dragging in most of the rest of the afs
 * includes as dependencies.
 */
#define VNAMESIZE 32

#include <com_err.h>
#include <krb.h>
#include <krb5.h>

#include "locker.h"
#include "locker_private.h"

/* Cheesy test for determining AFS 3.5. */
#ifndef AFSCONF_CLIENTNAME
#define AFS35
#endif

#ifdef AFS35
#include <afs/dirpath.h>
#else
#define AFSDIR_CLIENT_ETC_DIRPATH AFSCONF_CLIENTNAME
#endif

/*
 * Why doesn't AFS provide this prototype?
 */
extern int pioctl(char *, afs_int32, struct ViceIoctl *, afs_int32);

static int afs_parse(locker_context context, char *name, char *desc,
                     char *mountpoint, locker_attachent **at);
static int afs_attach(locker_context context, locker_attachent *at,
                      char *mountoptions);
static int afs_detach(locker_context context, locker_attachent *at);
static int afs_auth(locker_context context, locker_attachent *at,
                    int mode, int op);
static int afs_zsubs(locker_context context, locker_attachent *at);

struct locker_ops locker__afs_ops = {
  "AFS",
  0,
  afs_parse,
  afs_attach,
  afs_detach,
  afs_auth,
  afs_zsubs
};

static int afs_get_cred(krb5_context context, char *name, char *inst, char *realm,
                        krb5_creds **creds);
static int afs_maybe_auth_to_cell(locker_context context, char *name,
                                  char *cell, int op, int force);
static int get_user_realm(krb5_context context, char *realm);
static char *afs_realm_of_cell(krb5_context, struct afsconf_cell *);

extern int krb524_convert_creds_kdc(krb5_context, krb5_creds *, CREDENTIALS *);

static int afs_parse(locker_context context, char *name, char *desc,
                     char *mountpoint, locker_attachent **atp)
{
  locker_attachent *at;
  char *p, *dup = NULL, *lasts = NULL;
  int status;

  at = locker__new_attachent(context, &locker__afs_ops);
  if (!at)
    return LOCKER_ENOMEM;

  if (!name)
    {
      /* This is an explicit description. */

      if (strncmp(desc, "/afs/", 5))
        {
          locker__error(context, "%s: Path is not in AFS.\n", desc);
          status = LOCKER_EPARSE;
          goto cleanup;
        }

      at->name = strdup(desc);
      at->hostdir = strdup(desc);
      if (mountpoint)
        at->mountpoint = strdup(mountpoint);
      else
        {
          p = strrchr(desc, '/') + 1;
          at->mountpoint = malloc(strlen(context->afs_mount_dir) +
                                  strlen(p) + 2);
          if (at->mountpoint)
            sprintf(at->mountpoint, "%s/%s", context->afs_mount_dir, p);
        }
      if (!at->name || !at->hostdir || !at->mountpoint)
        goto mem_error;

      at->mode = LOCKER_AUTH_READWRITE;
    }
  else
    {
      /* A Hesiod AFS description looks like:
       * AFS /afs/dev.mit.edu/source/src-current w /mit/source
       */

      at->name = strdup(name);
      if (!at->name)
        goto mem_error;

      dup = strdup(desc);
      if (!dup)
        goto mem_error;

      /* Skip "AFS". */
      if (!strtok_r(dup, " ", &lasts))
        goto parse_error;

      /* Hostdir */
      at->hostdir = strtok_r(NULL, " ", &lasts);
      if (!at->hostdir)
        goto parse_error;
      if (strncmp(at->hostdir, "/afs/", 5))
        {
          locker__error(context, "%s: Path \"%s\" is not in AFS.\n", name,
                        at->hostdir);
          status = LOCKER_EPARSE;
          goto cleanup;
        }
      at->hostdir = strdup(at->hostdir);
      if (!at->hostdir)
        goto mem_error;

      /* Auth mode */
      p = strtok_r(NULL, " ", &lasts);
      if (!p || *(p + 1))
        goto parse_error;

      switch (*p)
        {
        case 'r':
          at->mode = LOCKER_AUTH_READONLY;
          break;
        case 'w':
          at->mode = LOCKER_AUTH_READWRITE;
          break;
        case 'n':
          at->mode = LOCKER_AUTH_NONE;
          break;
        default:
          locker__error(context, "%s: Unrecognized auth mode '%c' in "
                        "description:\n%s\n", name, *p, desc);
          status = LOCKER_EPARSE;
          goto cleanup;
        }

      /* Mountpoint */
      p = strtok_r(NULL, " ", &lasts);
      if (!p)
        goto parse_error;
      if (mountpoint)
        at->mountpoint = strdup(mountpoint);
      else
        at->mountpoint = strdup(p);
      if (!at->mountpoint)
        goto mem_error;

      free(dup);
      dup = NULL;
    }

  status = locker__canonicalize_path(context, LOCKER_CANON_CHECK_MOST,
                                     &(at->mountpoint), &(at->buildfrom));
  if (status != LOCKER_SUCCESS)
    goto cleanup;

  *atp = at;
  return LOCKER_SUCCESS;

mem_error:
  locker__error(context, "Out of memory parsing locker description.\n");
  status = LOCKER_ENOMEM;
  goto cleanup;

parse_error:
  locker__error(context, "Could not parse locker description "
                "\"%s\".\n", desc);
  status = LOCKER_EPARSE;

cleanup:
  free(dup);
  locker_free_attachent(context, at);
  return status;
}

static int afs_attach(locker_context context, locker_attachent *at,
                      char *mountoptions)
{
  struct stat st1, st2;
  struct ViceIoctl vio;
  afs_int32 hosts[8]; /* AFS docs say VIOCWHEREIS won't return more than 8. */
  uid_t uid = geteuid();
  int status;

  /* Make sure user can read the destination, and it's a directory. */
  if (uid != context->user)
    seteuid(context->user);
  status = lstat(at->hostdir, &st1);
  if (uid != context->user)
    seteuid(uid);

  if (status == -1)
    {
     if (errno == ETIMEDOUT)
        {
          locker__error(context, "%s: Connection timed out while trying to "
                        "attach locker.\nThis probably indicates a temporary "
                        "problem with the file server containing\n"
                        "this locker. Try again later.\n", at->name);
        }
      else
        {
          locker__error(context, "%s: Could not attach locker:\n%s for %s\n",
                        at->name, strerror(errno), at->hostdir);
        }
      return LOCKER_EATTACH;
    }
  if (!S_ISDIR(st1.st_mode) && !S_ISLNK(st1.st_mode))
    {
      locker__error(context, "%s: Could not attach locker:\n"
                    "%s is not a directory.\n", at->name, at->hostdir);
      return LOCKER_EATTACH;
    }

  /* Make sure nothing is already mounted on our mountpoint. */
  status = stat(at->mountpoint, &st2);
  if (!status)
    {
      /* Assume the automounter took care of it */
    }
  else
    {
    status = symlink(at->hostdir, at->mountpoint);
    if (status < 0)
      {
        locker__error(context, "%s: Could not attach locker:\n%s while "
                    "symlinking %s to %s\n", at->name, strerror(errno),
                    at->hostdir, at->mountpoint);
        return LOCKER_EATTACH;
      }
    }

  /* Find host that the locker is on, and update the attachent. */
  memset(hosts, 0, sizeof(hosts));
  vio.in_size = 0;
  vio.out = (caddr_t)hosts;
  vio.out_size = sizeof(hosts);
  if (pioctl(at->hostdir, VIOCWHEREIS, &vio, 1) == 0)
    {
      /* Only record the hostaddr if the locker is on a single host.
       * (We assume that if it's on multiple hosts, it can't fail,
       * so we don't need to know what those hosts are.)
       */
      if (!hosts[1])
        at->hostaddr.s_addr = hosts[0];
    }

  return LOCKER_SUCCESS;
}

static int afs_detach(locker_context context, locker_attachent *at)
{
  int status;

  /* Let the automounter manage the symlink */
  /* status = unlink(at->mountpoint);
  if (status < 0)
    {
      if (errno == ENOENT)
        {
          locker__error(context, "%s: Locker is not attached.\n", at->name);
          return LOCKER_ENOTATTACHED;
        }
      else
        {
          locker__error(context, "%s: Could not detach locker:\n%s while "
                        "trying to unlink %s.\n", at->name, strerror(errno),
                        at->mountpoint);
          return LOCKER_EDETACH;
        }
    }
  */
  return LOCKER_SUCCESS;
}

static int afs_auth(locker_context context, locker_attachent *at,
                    int mode, int op)
{
  char *cell, *p;
  int status;

  if (op != LOCKER_AUTH_AUTHENTICATE)
    return LOCKER_SUCCESS;

  /* We know (from afs_parse) that at->hostdir starts with "/afs/". */
  cell = at->hostdir + 5;
  /* Skip initial "." in the cell name (if this is a path to a rw volume). */
  if (*cell == '.')
    cell++;

  p = strchr(cell, '/');
  if (p)
    *p = '\0';
  status = afs_maybe_auth_to_cell(context, at->name, cell, op, 0);
  if (p)
    *p = '/';
  return status;
}

int locker_auth_to_cell(locker_context context, char *name, char *cell, int op)
{
  return afs_maybe_auth_to_cell(context, name, cell, op, 1);
}

static int afs_maybe_auth_to_cell(locker_context context, char *name,
                                  char *cell, int op, int force)
{
  char *crealm, urealm[REALM_SZ], *user = NULL;
  int status;
  struct afsconf_dir *configdir;
  struct afsconf_cell cellconfig;
  struct ktc_principal server, client, xclient;
  struct ktc_token token, xtoken;
  afs_int32 vice_id;
  uid_t uid = geteuid(), ruid = getuid();
  krb5_context v5context;
  krb5_creds *v5cred = NULL;

  if (op != LOCKER_AUTH_AUTHENTICATE)
    return LOCKER_SUCCESS;

  /* Find the cell's db servers. */
  configdir = afsconf_Open(AFSDIR_CLIENT_ETC_DIRPATH);
  if (!configdir)
    {
      locker__error(context, "%s: Could not authenticate to AFS: "
                    "error opening CellServDB file.\n", name);
      return LOCKER_EAUTH;
    }
  status = afsconf_GetCellInfo(configdir, cell, NULL, &cellconfig);
  afsconf_Close(configdir);
  if (status)
    {
      initialize_acfg_error_table();
      locker__error(context, "%s: Could not authenticate to AFS:\n%s while "
                    "reading CellServDB file.\n", name, error_message(status));
      return LOCKER_EAUTH;
    }

  /* Canonicalize the cell name. */
  cell = cellconfig.name;

  /* Get tickets for the realm containing the cell's servers. (Set uid
   * to the user before touching the ticket file.) Try
   * afs.cellname@realm first, and afs@realm if that doesn't exist.
   */
  status = krb5_init_context(&v5context);
  if (status)
    {
      locker__error(context, "%s: Could not establish krb5 context: %s\n",
                    name, error_message(status));
      return LOCKER_EAUTH;
    }
  crealm = afs_realm_of_cell(v5context, &cellconfig);
  if (uid != ruid)
    seteuid(ruid);
  status = afs_get_cred(v5context, "afs", cell, crealm, &v5cred);
  if (status)
    status = afs_get_cred(v5context, "afs", "", crealm, &v5cred);
  if (uid != ruid)
    seteuid(uid);
  if (status)
    {
      if (status == KRB5_FCC_NOFILE)
        {
          locker__error(context, "%s: Could not authenticate to AFS: %s.\n",
                        name, error_message(status));
        }
      else
        {
          locker__error(context, "%s: Could not authenticate to AFS cell "
                        "%s:\n%s while getting tickets for %s.\n",
                        name, cell, error_message(status), crealm);
        }
      krb5_free_context(v5context);
      return LOCKER_EAUTH;
    }
  status = get_user_realm(v5context, urealm);
  if (status)
    {
      locker__error(context, "Couldn't obtain user's realm.\n");
      return LOCKER_EAUTH;
    }

  /*
   * Create a token from the ticket.
   * (This code is shamelessly stolen from aklog.)
   */

  if (! context->use_krb4)
    {
      char *p;
      char *pname, *pinst = NULL;
      int pnamelen, pinstlen = 0;

      /* Using Kerberos V5 ticket natively via rxkad 2b */

      pname    = krb5_princ_component(v5context, v5cred->client, 0)->data;
      pnamelen = krb5_princ_component(v5context, v5cred->client, 0)->length;

      if (krb5_princ_size(v5context, v5cred->client) > 1)
        {
          pinst    = krb5_princ_component(v5context, v5cred->client, 1)->data;
          pinstlen = krb5_princ_component(v5context, v5cred->client, 1)->length;
        }

      user = malloc(pnamelen + pinstlen + strlen(urealm) + 3);
      if (!user)
        {
          locker__error(context, "Out of memory authenticating to cell.\n");
          return LOCKER_ENOMEM;
        }

      strncpy(user, pname, pnamelen);
      user[pnamelen] = '\0';

      if (pinst)
        {
          strcat(user, ".");
          p = user + strlen(user);
          strncpy(p, pinst, pinstlen);
          p[pinstlen] = '\0';
        }

      if (strcasecmp(crealm, urealm))
        sprintf(user + strlen(user), "@%s", urealm);

      memset(&token, 0, sizeof(token));
      token.kvno = RXKAD_TKT_TYPE_KERBEROS_V5;
      token.startTime = v5cred->times.starttime;;
      token.endTime = v5cred->times.endtime;
      memcpy(&token.sessionKey, v5cred->keyblock.contents,
             v5cred->keyblock.length);
      token.ticketLen = v5cred->ticket.length;
      memcpy(token.ticket, v5cred->ticket.data, token.ticketLen);
    } 
  else 
    {
      CREDENTIALS cred;

      /* Using Kerberos 524 translator service */

      status = krb5_524_convert_creds(v5context, v5cred, &cred);

      if (status)
        {
          locker__error(context, "%s: Could not convert tickets "
                        "to Kerberos V4 format: %s.\n",
                        name, error_message(status));
          krb5_free_context(v5context);
          return LOCKER_EAUTH;
        }

      user = malloc(strlen(cred.pname) + strlen(cred.pinst) + strlen(urealm) + 3);
      if (!user)
        {
          locker__error(context, "Out of memory authenticating to cell.\n");
          return LOCKER_ENOMEM;
        }

      strcpy(user, cred.pname);
      if (*cred.pinst)
        sprintf(user + strlen(user), ".%s", cred.pinst);
      if (strcasecmp(crealm, urealm))
        sprintf(user + strlen(user), "@%s", urealm);

      token.kvno = cred.kvno;
      token.startTime = cred.issue_date;
      token.endTime = v5cred->times.endtime;
      memcpy(&token.sessionKey, cred.session, sizeof(token.sessionKey));
      token.ticketLen = cred.ticket_st.length;
      memcpy(token.ticket, cred.ticket_st.dat, token.ticketLen);
    }

  krb5_free_creds(v5context, v5cred);
  krb5_free_context(v5context);

  /* Look up principal's PTS id. */
  status = pr_Initialize(0, (char *)AFSDIR_CLIENT_ETC_DIRPATH, cell);
  if (status)
    {
      locker__error(context, "%s: Could not initialize AFS protection "
                    "library while authenticating to cell \"%s\":\n%s.\n",
                    name, cell, error_message(status));
      free(user);
      return LOCKER_EAUTH;
    }
  status = pr_SNameToId(user, &vice_id);
  if (status)
    {
      locker__error(context, "%s: Could not find AFS PTS id for user \"%s\""
                    "in cell \"%s\":\n%s.\n", name, user, cell,
                    error_message(status));
      free(user);
      return LOCKER_EAUTH;
    }

  /* Select appropriate dead chicken to wave. */
  if (vice_id == ANONYMOUSID)
    strncpy(client.name, user, MAXKTCNAMELEN - 1);
  else
    sprintf(client.name, "AFS ID %ld", (long) vice_id);
  strcpy(client.instance, "");
  strncpy(client.cell, crealm, MAXKTCREALMLEN - 1);
  client.cell[MAXKTCREALMLEN - 1] = '\0';

  strcpy(server.name, "afs");
  strcpy(server.instance, "");
  strncpy(server.cell, cell, MAXKTCREALMLEN - 1);
  server.cell[MAXKTCREALMLEN - 1] = '\0';

  if (!force)
    {
      /* Check for an existing token. */
      status = ktc_GetToken(&server, &xtoken, sizeof(token), &xclient);
      if (!status)
        {
          /* Don't get tokens as another user. */
          if (strcmp(xclient.name, client.name))
            {
              free(user);
              return LOCKER_SUCCESS;
            }

          /* Don't get tokens that won't last longer than existing tokens. */
          if (token.endTime <= xtoken.endTime)
            {
              free(user);
              return LOCKER_SUCCESS;
            }
        }
    }

  /* Store the token. */
  status = ktc_SetToken(&server, &token, &client, 0);
  if (status)
    {
      locker__error(context, "%s: Could not obtain %s tokens for cell "
                    "%s:\n%s.\n", name, user, cell, error_message(status));
      free(user);
      return LOCKER_EAUTH;
    }

  free(user);
  return LOCKER_SUCCESS;
}

static int afs_get_cred(krb5_context context, char *name, char *inst, char *realm,
                        krb5_creds **creds)
{
  krb5_creds increds;
  krb5_principal client_principal = NULL;
  krb5_ccache krb425_ccache = NULL;
  krb5_error_code retval = 0;

  memset(&increds, 0, sizeof(increds));
  /* ANL - instance may be ptr to a null string. Pass null then */
  retval = krb5_build_principal(context, &increds.server, strlen(realm),
                                realm, name,
                                (inst && strlen(inst)) ? inst : NULL,
                                NULL);
  if (retval)
    goto fail;

  retval = krb5_cc_default(context, &krb425_ccache);
  if (retval)
    goto fail;

  retval = krb5_cc_get_principal(context, krb425_ccache, &client_principal);
  if (retval)
    goto fail;

  increds.client = client_principal;
  increds.times.endtime = 0;
  /* Ask for DES since that is what V4 understands */
  increds.keyblock.enctype = ENCTYPE_DES_CBC_CRC;

  retval = krb5_get_credentials(context, 0, krb425_ccache, &increds, creds);

fail:
  krb5_free_cred_contents(context, &increds);
  if (krb425_ccache)
    krb5_cc_close(context, krb425_ccache);
  return(retval);
}

static int afs_zsubs(locker_context context, locker_attachent *at)
{
  struct ViceIoctl vio;
  char *path, *last_component, *p, *subs[3];
  char cell[MAXCELLCHARS + 1], vol[VNAMESIZE + 1];
  char cellvol[MAXCELLCHARS + VNAMESIZE + 2];
  afs_int32 hosts[8];
  int status = 0, pstatus;
  struct hostent *h;

  subs[0] = cell;
  subs[1] = cellvol;

  path = strdup(at->hostdir);
  if (!path)
    {
      locker__error(context, "Out of memory getting zephyr subscriptions.\n");
      return LOCKER_ENOMEM;
    }

  /* Walk down the path. At each level, add subscriptions for the cell,
   * host, and volume where that path component lives.
   */
  p = path;
  do
    {
      /* Move trailing NUL over one pathname component. */
      *p = '/';
      p = strchr(p + 1, '/');
      if (p)
        *p = '\0';

      /* Get cell */
      vio.in_size = 0;
      vio.out = cell;
      vio.out_size = sizeof(cell);
      if (pioctl(path, VIOC_FILE_CELL_NAME, &vio, 1) != 0)
        continue;

      /* Get mountpoint name and generate cell:mountpoint. */
      last_component = strrchr(path, '/');
      if (last_component)
        {
          *last_component++ = '\0';
          vio.in = last_component;
        }
      else
        vio.in = "/";
      vio.in_size = strlen(vio.in) + 1;
      vio.out = vol;
      vio.out_size = sizeof(vol);
      pstatus = pioctl(path, VIOC_AFS_STAT_MT_PT, &vio, 1);
      if (last_component)
        *(last_component - 1) = '/';

      if (pstatus != 0)
        continue;

      /* Get cell:volumname into cellvol, ignoring initial '#' or '%'. */
      if (strchr(vol, ':'))
        strcpy(cellvol, vol + 1);
      else
        sprintf(cellvol, "%s:%s", cell, vol + 1);

      /* If there's only one site for this volume, add the hostname
       * of the server to the subs list.
       */
      memset(hosts, 0, 2 * sizeof(*hosts));
      vio.out = (caddr_t)hosts;
      vio.out_size = sizeof(hosts);
      if (pioctl(path, VIOCWHEREIS, &vio, 1) != 0)
        continue;
      if (!hosts[1])
        {
          h = gethostbyaddr((char *)&hosts[0], 4, AF_INET);
          if (!h)
            continue;
          subs[2] = h->h_name;
          status = locker__add_zsubs(context, subs, 3);
        }
      else
        status = locker__add_zsubs(context, subs, 2);
    }
  while (status == LOCKER_SUCCESS && strlen(path) != strlen(at->hostdir));

  free(path);
  return status;
}

/* librxkad depends on this symbol in Transarc's des library, which we
 * can't link with because of conflicts with our krb4 library. It never
 * gets called though.
 */
void des_pcbc_init(void)
{
  abort();
}

static char *afs_realm_of_cell(context, cellconfig)
     krb5_context context;
     struct afsconf_cell *cellconfig;
{
  static char krbrlm[REALM_SZ+1];
  char **hrealms = 0;

  if (!cellconfig)
    return 0;
  if (krb5_get_host_realm(context, cellconfig->hostName[0], &hrealms))
    return 0;
  if (!hrealms[0])
    return 0;
  strcpy(krbrlm, hrealms[0]);

  if (hrealms)
    free(hrealms);

  return krbrlm;
}

static int get_user_realm(krb5_context context, char *realm)
{
  krb5_principal client_principal = NULL;
  krb5_ccache krb425_ccache = NULL;
  krb5_error_code retval = 0;
  int i;

  retval = krb5_cc_default(context, &krb425_ccache);
  if (retval)
    goto fail;

  retval = krb5_cc_get_principal(context, krb425_ccache, &client_principal);
  if (retval)
    goto fail;

  i = krb5_princ_realm(context, client_principal)->length;
  if (i > REALM_SZ - 1)
    i = REALM_SZ - 1;
  memcpy(realm, krb5_princ_realm(context, client_principal)->data, i);
  realm[i] = '\0';

fail:
  if (krb425_ccache)
    krb5_cc_close(context, krb425_ccache);
  if (client_principal)
    krb5_free_principal(context, client_principal);

  return retval;
}