1 files changed, 324 insertions, 0 deletions
diff --git a/hurd/lookup-retry.c b/hurd/lookup-retry.c
new file mode 100644
index 0000000000..34b0674561
--- /dev/null
+++ b/hurd/lookup-retry.c
@@ -0,0 +1,324 @@
+/* hairy bits of Hurd file name lookup
+   Copyright (C) 1992,93,94,95,96,97,99,2001 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Library General Public License as
+   published by the Free Software Foundation; either version 2 of the
+   License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If not,
+   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+#include <hurd.h>
+#include <hurd/lookup.h>
+#include <hurd/term.h>
+#include <hurd/paths.h>
+#include <limits.h>
+#include <fcntl.h>
+#include <string.h>
+#include "stdio-common/_itoa.h"
+
+/* Translate the error from dir_lookup into the error the user sees.  */
+static inline error_t
+lookup_error (error_t error)
+{
+  switch (error)
+    {
+    case EOPNOTSUPP:
+    case MIG_BAD_ID:
+      /* These indicate that the server does not understand dir_lookup
+	 at all.  If it were a directory, it would, by definition.  */
+      return ENOTDIR;
+    default:
+      return error;
+    }
+}
+
+error_t
+__hurd_file_name_lookup_retry (error_t (*use_init_port)
+			         (int which, error_t (*operate) (file_t)),
+			       file_t (*get_dtable_port) (int fd),
+			       error_t (*lookup)
+			         (file_t dir, char *name,
+				  int flags, mode_t mode,
+				  retry_type *do_retry, string_t retry_name,
+				  mach_port_t *result),
+			       enum retry_type doretry,
+			       char retryname[1024],
+			       int flags, mode_t mode,
+			       file_t *result)
+{
+  error_t err;
+  char *file_name;
+  int nloops;
+
+  error_t lookup_op (file_t startdir)
+    {
+      while (file_name[0] == '/')
+	file_name++;
+
+      return lookup_error ((*lookup) (startdir, file_name, flags, mode,
+				      &doretry, retryname, result));
+    }
+  error_t reauthenticate (file_t unauth)
+    {
+      error_t err;
+      mach_port_t ref = __mach_reply_port ();
+      error_t reauth (auth_t auth)
+	{
+	  return __auth_user_authenticate (auth, ref,
+					   MACH_MSG_TYPE_MAKE_SEND,
+					   result);
+	}
+      err = __io_reauthenticate (unauth, ref, MACH_MSG_TYPE_MAKE_SEND);
+      if (! err)
+	err = (*use_init_port) (INIT_PORT_AUTH, &reauth);
+      __mach_port_destroy (__mach_task_self (), ref);
+      __mach_port_deallocate (__mach_task_self (), unauth);
+      return err;
+    }
+
+  if (! lookup)
+    lookup = __dir_lookup;
+
+  nloops = 0;
+  err = 0;
+  do
+    {
+      file_t startdir = MACH_PORT_NULL;
+      int dirport = INIT_PORT_CWDIR;
+
+      switch (doretry)
+	{
+	case FS_RETRY_REAUTH:
+	  if (err = reauthenticate (*result))
+	    return err;
+	  /* Fall through.  */
+
+	case FS_RETRY_NORMAL:
+	  if (nloops++ >= SYMLOOP_MAX)
+	    {
+	      __mach_port_deallocate (__mach_task_self (), *result);
+	      return ELOOP;
+	    }
+
+	  /* An empty RETRYNAME indicates we have the final port.  */
+	  if (retryname[0] == '\0' &&
+	      /* If reauth'd, we must do one more retry on "" to give the new
+		 translator a chance to make a new port for us.  */
+	      doretry == FS_RETRY_NORMAL)
+	    {
+	      if (flags & O_NOFOLLOW)
+		{
+		  /* In Linux, O_NOFOLLOW means to reject symlinks.  If we
+		     did an O_NOLINK lookup above and io_stat here to check
+		     for S_IFLNK, a translator like firmlink could easily
+		     spoof this check by not showing S_IFLNK, but in fact
+		     redirecting the lookup to some other name
+		     (i.e. opening the very same holes a symlink would).
+
+		     Instead we do an O_NOTRANS lookup above, and stat the
+		     underlying node: if it has a translator set, and its
+		     owner is not root (st_uid 0) then we reject it.
+		     Since the motivation for this feature is security, and
+		     that security presumes we trust the containing
+		     directory, this check approximates the security of
+		     refusing symlinks while accepting mount points.
+		     Note that we actually permit something Linux doesn't:
+		     we follow root-owned symlinks; if that is deemed
+		     undesireable, we can add a final check for that
+		     one exception to our general translator-based rule.  */
+		  struct stat st;
+		  err = __io_stat (*result, &st);
+		  if (!err
+		      && (st.st_mode & (S_IPTRANS|S_IATRANS)))
+		    {
+		      if (st.st_uid != 0)
+			err = ENOENT;
+		      else if (st.st_mode & S_IPTRANS)
+			{
+			  char buf[1024];
+			  char *trans = buf;
+			  size_t translen = sizeof buf;
+			  err = __file_get_translator (*result,
+						       &trans, &translen);
+			  if (!err
+			      && translen > sizeof _HURD_SYMLINK
+			      && !memcmp (trans,
+					  _HURD_SYMLINK, sizeof _HURD_SYMLINK))
+			    err = ENOENT;
+			}
+		    }
+		}
+
+	      /* We got a successful translation.  Now apply any open-time
+		 action flags we were passed.  */
+
+	      if (!err && (flags & O_TRUNC)) /* Asked to truncate the file.  */
+		err = __file_set_size (*result, 0);
+
+	      if (err)
+		__mach_port_deallocate (__mach_task_self (), *result);
+	      return err;
+	    }
+
+	  startdir = *result;
+	  file_name = retryname;
+	  break;
+
+	case FS_RETRY_MAGICAL:
+	  switch (retryname[0])
+	    {
+	    case '/':
+	      dirport = INIT_PORT_CRDIR;
+	      if (*result != MACH_PORT_NULL)
+		__mach_port_deallocate (__mach_task_self (), *result);
+	      if (nloops++ >= SYMLOOP_MAX)
+		return ELOOP;
+	      file_name = &retryname[1];
+	      break;
+
+	    case 'f':
+	      if (retryname[1] == 'd' && retryname[2] == '/')
+		{
+		  int fd;
+		  char *end;
+		  int save = errno;
+		  errno = 0;
+		  fd = (int) strtol (&retryname[3], &end, 10);
+		  if (end == NULL || errno || /* Malformed number.  */
+		      /* Check for excess text after the number.  A slash
+			 is valid; it ends the component.  Anything else
+			 does not name a numeric file descriptor.  */
+		      (*end != '/' && *end != '\0'))
+		    {
+		      errno = save;
+		      return ENOENT;
+		    }
+		  if (! get_dtable_port)
+		    err = EGRATUITOUS;
+		  else
+		    {
+		      *result = (*get_dtable_port) (fd);
+		      if (*result == MACH_PORT_NULL)
+			{
+			  /* If the name was a proper number, but the file
+			     descriptor does not exist, we return EBADF instead
+			     of ENOENT.  */
+			  err = errno;
+			  errno = save;
+			}
+		    }
+		  errno = save;
+		  if (err)
+		    return err;
+		  if (*end == '\0')
+		    return 0;
+		  else
+		    {
+		      /* Do a normal retry on the remaining components.  */
+		      startdir = *result;
+		      file_name = end + 1; /* Skip the slash.  */
+		      break;
+		    }
+		}
+	      else
+		goto bad_magic;
+	      break;
+
+	    case 'm':
+	      if (retryname[1] == 'a' && retryname[2] == 'c' &&
+		  retryname[3] == 'h' && retryname[4] == 't' &&
+		  retryname[5] == 'y' && retryname[6] == 'p' &&
+		  retryname[7] == 'e')
+		{
+		  error_t err;
+		  struct host_basic_info hostinfo;
+		  mach_msg_type_number_t hostinfocnt = HOST_BASIC_INFO_COUNT;
+		  char *p;
+		  /* XXX want client's host */
+		  if (err = __host_info (__mach_host_self (), HOST_BASIC_INFO,
+					 (natural_t *) &hostinfo,
+					 &hostinfocnt))
+		    return err;
+		  if (hostinfocnt != HOST_BASIC_INFO_COUNT)
+		    return EGRATUITOUS;
+		  p = _itoa (hostinfo.cpu_subtype, &retryname[8], 10, 0);
+		  *--p = '/';
+		  p = _itoa (hostinfo.cpu_type, &retryname[8], 10, 0);
+		  if (p < retryname)
+		    abort ();	/* XXX write this right if this ever happens */
+		  if (p > retryname)
+		    strcpy (retryname, p);
+		  startdir = *result;
+		}
+	      else
+		goto bad_magic;
+	      break;
+
+	    case 't':
+	      if (retryname[1] == 't' && retryname[2] == 'y')
+		switch (retryname[3])
+		  {
+		    error_t opentty (file_t *result)
+		      {
+			error_t err;
+			error_t ctty_open (file_t port)
+			  {
+			    if (port == MACH_PORT_NULL)
+			      return ENXIO; /* No controlling terminal.  */
+			    return __termctty_open_terminal (port,
+							     flags,
+							     result);
+			  }
+			err = (*use_init_port) (INIT_PORT_CTTYID, &ctty_open);
+			if (! err)
+			  err = reauthenticate (*result);
+			return err;
+		      }
+
+		  case '\0':
+		    return opentty (result);
+		  case '/':
+		    if (err = opentty (&startdir))
+		      return err;
+		    strcpy (retryname, &retryname[4]);
+		    break;
+		  default:
+		    goto bad_magic;
+		  }
+	      else
+		goto bad_magic;
+	      break;
+
+	    default:
+	    bad_magic:
+	      return EGRATUITOUS;
+	    }
+	  break;
+
+	default:
+	  return EGRATUITOUS;
+	}
+
+      if (startdir != MACH_PORT_NULL)
+	{
+	  err = lookup_op (startdir);
+	  __mach_port_deallocate (__mach_task_self (), startdir);
+	  startdir = MACH_PORT_NULL;
+	}
+      else
+	err = (*use_init_port) (dirport, &lookup_op);
+    } while (! err);
+
+  return err;
+}
+weak_alias (__hurd_file_name_lookup_retry, hurd_file_name_lookup_retry)