Update.

2000-09-26  Ulrich Drepper  <drepper@redhat.com>

	* sysdeps/unix/sysv/linux/gethostid.c (sethostid): Use O_TRUNC to
	remove possible garbage at the end of the file.

	* stdio-common/tmpnam_r.c: Warn about insecure tmpnam_r.
	* stdio-common/tmpnam.c: Warn about insecure tmpnam.
	* stdio-common/tempnam.c: Warn about insecure tempnam.
	* misc/mktemp.c: Warn about insecure mktemp.

ChangeLog

@@ -1,5 +1,15 @@
+2000-09-26  Ulrich Drepper  <drepper@redhat.com>
+
+	* sysdeps/unix/sysv/linux/gethostid.c (sethostid): Use O_TRUNC to
+	remove possible garbage at the end of the file.
+
 2000-09-25  Ulrich Drepper  <drepper@redhat.com>
 
+	* stdio-common/tmpnam_r.c: Warn about insecure tmpnam_r.
+	* stdio-common/tmpnam.c: Warn about insecure tmpnam.
+	* stdio-common/tempnam.c: Warn about insecure tempnam.
+	* misc/mktemp.c: Warn about insecure mktemp.
+
 	* sysdeps/unix/sysv/linux/check_fds.c: New file.
 	* sysdeps/generic/check_fds.c: Check that file opened is really
 	/dev/null.

manual/filesys.texi

@@ -2870,7 +2870,7 @@ file is created another process might have created a file with the same
 name using @code{tmpnam}, leading to a possible security hole.  The
 implementation generates names which can hardly be predicted, but when
 opening the file you should use the @code{O_EXCL} flag.  Using
-@code{tmpfile} is a safe way to avoid this problem.
+@code{tmpfile} or @code{mkstemp} is a safe way to avoid this problem.
 @end deftypefun
 
 @comment stdio.h
@@ -2881,6 +2881,9 @@ that if @var{result} is a null pointer it returns a null pointer.
 
 This guarantees reentrancy because the non-reentrant situation of
 @code{tmpnam} cannot happen here.
+
+@strong{Warning}: This function has the same security problems as
+@code{tmpnam}.
 @end deftypefun
 
 @comment stdio.h
@@ -2937,6 +2940,13 @@ The directory @file{/tmp}.
 @end itemize
 
 This function is defined for SVID compatibility.
+
+@strong{Warning:} Between the time the pathname is constructed and the
+file is created another process might have created a file with the same
+name using @code{tempnam}, leading to a possible security hole.  The
+implementation generates names which can hardly be predicted, but when
+opening the file you should use the @code{O_EXCL} flag.  Using
+@code{tmpfile} or @code{mkstemp} is a safe way to avoid this problem.
 @end deftypefun
 @cindex TMPDIR environment variable
 

misc/mktemp.c

@@ -1,4 +1,4 @@
-/* Copyright (C) 1998, 1999 Free Software Foundation, Inc.
+/* Copyright (C) 1998, 1999, 2000 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
@@ -32,3 +32,5 @@ mktemp (template)
 
   return template;
 }
+
+link_warning (mktemp, "the use of `mktemp' is dangerous, better use `mkstemp'")

stdio-common/tempnam.c

@@ -1,4 +1,4 @@
-/* Copyright (C) 1991,1993,1996,1997,1998,1999 Free Software Foundation, Inc.
+/* Copyright (C) 1991,1993,1996-1999,2000 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
@@ -39,3 +39,6 @@ tempnam (const char *dir, const char *pfx)
 
   return __strdup (buf);
 }
+
+link_warning (tempnam,
+	      "the use of `tempnam' is dangerous, better use `mkstemp'")

stdio-common/tmpnam.c

@@ -1,4 +1,4 @@
-/* Copyright (C) 1991,1993,1996,1997,1998,1999 Free Software Foundation, Inc.
+/* Copyright (C) 1991,1993,1996-1999,2000 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
@@ -45,3 +45,6 @@ tmpnam (char *s)
 
   return s;
 }
+
+link_warning (tmpnam,
+	      "the use of `tmpnam' is dangerous, better use `mkstemp'")

stdio-common/tmpnam_r.c

@@ -1,4 +1,4 @@
-/* Copyright (C) 1991,1993,1996,1997,1998,1999 Free Software Foundation, Inc.
+/* Copyright (C) 1991,1993,1996-1999,2000 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
@@ -33,3 +33,6 @@ tmpnam_r (char *s)
 
   return s;
 }
+
+link_warning (tmpnam_r,
+	      "the use of `tmpnam_r' is dangerous, better use `mkstemp'")

sysdeps/unix/sysv/linux/gethostid.c

@@ -1,4 +1,4 @@
-/* Copyright (C) 1995, 1996, 1998, 1999 Free Software Foundation, Inc.
+/* Copyright (C) 1995, 1996, 1998, 1999, 2000 Free Software Foundation, Inc.
 
    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
@@ -40,7 +40,7 @@ sethostid (id)
     }
 
   /* Open file for writing.  Everybody is allowed to read this file.  */
-  fd = __open (HOSTIDFILE, O_CREAT|O_WRONLY, 0644);
+  fd = __open (HOSTIDFILE, O_CREAT|O_WRONLY|O_TRUNC, 0644);
   if (fd < 0)
     return -1;