imfs_eval.c

RTEMS (Real-Time Executive for Multiprocessor Systems) is a free open source real-time operating sys

/*
 *  Evaluation IMFS Node Support Routines
 *
 *  COPYRIGHT (c) 1989-1999.
 *  On-Line Applications Research Corporation (OAR).
 *
 *  The license and distribution terms for this file may be
 *  found in the file LICENSE in this distribution or at
 *  http://www.rtems.com/license/LICENSE.
 *
 *  $Id: imfs_eval.c,v 1.16.2.1 2003/09/04 18:47:02 joel Exp $
 */

#if HAVE_CONFIG_H
#include "config.h"
#endif

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <stdlib.h>
#include <assert.h>

#include "imfs.h"
#include <rtems/libio_.h>
#include <rtems/seterr.h>

#define RTEMS_LIBIO_PERMS_RX (RTEMS_LIBIO_PERMS_SEARCH | RTEMS_LIBIO_PERMS_READ)
#define RTEMS_LIBIO_PERMS_WX (RTEMS_LIBIO_PERMS_SEARCH | RTEMS_LIBIO_PERMS_WRITE)

#define MAXSYMLINK 5

int IMFS_Set_handlers(
  rtems_filesystem_location_info_t   *loc
)
{
  IMFS_jnode_t    *node = loc->node_access;
  IMFS_fs_info_t  *fs_info;

  fs_info = loc->mt_entry->fs_info;
  switch( node->type ) {
    case IMFS_DIRECTORY:
      loc->handlers = fs_info->directory_handlers;
      break;
    case IMFS_DEVICE:
      loc->handlers = &IMFS_device_handlers;
      break;
    case IMFS_SYM_LINK:
    case IMFS_HARD_LINK:
      loc->handlers = &IMFS_link_handlers;
      break;
    case IMFS_LINEAR_FILE:
      loc->handlers = fs_info->linearfile_handlers;
      break;
    case IMFS_MEMORY_FILE:
      loc->handlers = fs_info->memfile_handlers;
      break;
  }

  return 0;
}

/*
 *  IMFS_evaluate_permission
 *
 *  The following routine evaluates that we have permission
 *  to do flags on the node.
 */

int IMFS_evaluate_permission(
  rtems_filesystem_location_info_t  *node,
  int                                flags
)
{
  uid_t         st_uid;
  gid_t         st_gid;
  IMFS_jnode_t *jnode;
  int           flags_to_test;

  if ( !rtems_libio_is_valid_perms( flags ) ) {
    assert( 0 );
    rtems_set_errno_and_return_minus_one( EIO );    
  }

  jnode = node->node_access;

#if defined(RTEMS_POSIX_API)
  st_uid = geteuid();
  st_gid = getegid(); 
#else
  st_uid = jnode->st_uid;
  st_gid = jnode->st_gid;
#endif
  
  /*
   * Check if I am owner or a group member or someone else.
   */
  
  flags_to_test = flags;

  if ( st_uid == jnode->st_uid )
    flags_to_test <<= 6;
  else if ( st_gid == jnode->st_gid )
    flags_to_test <<= 3;
  else 
    /* must be other - do nothing */;

  /*
   * If all of the flags are set we have permission
   * to do this.
   */
  if ( ( flags_to_test & jnode->st_mode) == flags_to_test )
    return 1;

  return 0;
}

/*
 *  IMFS_evaluate_hard_link
 *
 *  The following routine evaluates a hardlink to the actual node.
 */

int IMFS_evaluate_hard_link(
  rtems_filesystem_location_info_t  *node,   /* IN/OUT */
  int                                flags   /* IN     */
)
{
  IMFS_jnode_t                     *jnode  = node->node_access;
  int                               result = 0;

  /*
   * Check for things that should never happen.
   */

  if ( jnode->type != IMFS_HARD_LINK )
    rtems_fatal_error_occurred (0xABCD0000);

  /*
   * Set the hard link value and the handlers.
   */

  node->node_access = jnode->info.hard_link.link_node;
  
  IMFS_Set_handlers( node );

  /*
   * Verify we have the correct permissions for this node.
   */

  if ( !IMFS_evaluate_permission( node, flags ) )
    rtems_set_errno_and_return_minus_one( EACCES );

  return result;
}


/* 
 *  IMFS_evaluate_sym_link
 *
 *  The following routine evaluates a symbolic link to the actual node.
 */

int IMFS_evaluate_sym_link( 
  rtems_filesystem_location_info_t  *node,   /* IN/OUT */
  int                                flags   /* IN     */
)
{
  IMFS_jnode_t                     *jnode  = node->node_access;
  int                               result = 0;
  int                               i;

  /*
   * Check for things that should never happen.
   */

  if ( jnode->type != IMFS_SYM_LINK )
    rtems_fatal_error_occurred (0xABCD0000);

  if ( !jnode->Parent )
    rtems_fatal_error_occurred( 0xBAD00000 );


  /*
   * Move the node_access to either the symbolic links parent or
   * root depending on the symbolic links path.
   */

  node->node_access = jnode->Parent;

  rtems_filesystem_get_sym_start_loc( 
    jnode->info.sym_link.name,
    &i,
    node
  );

  /*
   * Use eval path to evaluate the path of the symbolic link.
   */

  result = IMFS_eval_path(  
    &jnode->info.sym_link.name[i],
    flags,
    node
  );

  IMFS_Set_handlers( node );

  /*
   * Verify we have the correct permissions for this node.
   */

  if ( !IMFS_evaluate_permission( node, flags ) )
    rtems_set_errno_and_return_minus_one( EACCES );

  return result;
}

/*
 *  IMFS_evaluate_link
 *
 *  The following routine returns the real node pointed to by a link.
 */

int IMFS_evaluate_link( 
  rtems_filesystem_location_info_t  *node,   /* IN/OUT */
  int                                flags   /* IN     */
)
{
  IMFS_jnode_t                     *jnode;
  int                               result = 0;

  do {
    jnode  = node->node_access;

    /*
     * Increment and check the link counter.
     */

    rtems_filesystem_link_counts ++;
    if ( rtems_filesystem_link_counts > MAXSYMLINK ) {
      rtems_filesystem_link_counts = 0;
      rtems_set_errno_and_return_minus_one( ELOOP );
    }

    /*
     *  Follow the Link node.
     */

    if ( jnode->type == IMFS_HARD_LINK )
      result = IMFS_evaluate_hard_link( node, flags );

    else if (jnode->type == IMFS_SYM_LINK )
      result = IMFS_evaluate_sym_link( node, flags );

  } while ( ( result == 0 ) && ( ( jnode->type == IMFS_SYM_LINK  ) || 
                                 ( jnode->type == IMFS_HARD_LINK ) ) );

  /*
   * Clear link counter.
   */

  rtems_filesystem_link_counts = 0;

  return result;
}  


/*
 *  IMFS_evaluate_for_make
 *
 *  The following routine evaluate path for a new node to be created.
 *  pathloc is returned with a pointer to the parent of the new node.
 *  name is returned with a pointer to the first character in the 
 *  new node name.  The parent node is verified to be a directory.
 */

int IMFS_evaluate_for_make(
   const char                         *path,       /* IN     */
   rtems_filesystem_location_info_t   *pathloc,    /* IN/OUT */
   const char                        **name        /* OUT    */
)
{
  int                                 i = 0;
  int                                 len;
  IMFS_token_types                    type;
  char                                token[ IMFS_NAME_MAX + 1 ];
  rtems_filesystem_location_info_t    newloc;
  IMFS_jnode_t                       *node;
  int                                 done = 0;
  int                                 result; 
  
  /*
   * This was filled in by the caller and is valid in the
   * mount table.
   */
  node = pathloc->node_access;

  /*
   *  Evaluate all tokens until we are done or an error occurs.
   */

  while( !done ) {

    type = IMFS_get_token( &path[i], token, &len );
    i +=  len;
    
    if ( !pathloc->node_access )
      rtems_set_errno_and_return_minus_one( ENOENT );

    /*
     * I cannot move out of this directory without execute permission.
     */

    if ( type != IMFS_NO_MORE_PATH )
      if ( node->type == IMFS_DIRECTORY )
        if ( !IMFS_evaluate_permission( pathloc, RTEMS_LIBIO_PERMS_SEARCH ) )
           rtems_set_errno_and_return_minus_one( EACCES );

    node = pathloc->node_access;

    switch( type ) {

      case IMFS_UP_DIR:
       /*
        *  Am I at the root of all filesystems? (chroot'ed?)
	*/

       if ( pathloc->node_access == rtems_filesystem_root.node_access )