[PATCH] Require suid bit on audit objects in privileged programs

[Andreas Schwab <schwab at redhat dot com>]

2010-10-22  Andreas Schwab  <schwab@redhat.com>

	* include/dlfcn.h (__RTLD_SECURE): Define.
	* elf/dl-load.c (_dl_map_object): Remove preloaded parameter.  Use
	mode & __RTLD_SECURE instead.
	(open_path): Rename preloaded parameter to secure.
	* sysdeps/generic/ldsodefs.h (_dl_map_object): Adjust declaration.
	* elf/dl-open.c (dl_open_worker): Adjust call to _dl_map_object.
	* elf/dl-deps.c (openaux): Likewise.
	* elf/rtld.c (struct map_args): Remove is_preloaded.
	(map_doit): Don't use it.
	(dl_main): Likewise.
	(do_preload): Use __RTLD_SECURE instead of is_preloaded.
	(dlmopen_doit): Add __RTLD_SECURE to mode bits.
---
 elf/dl-deps.c              |    2 +-
 elf/dl-load.c              |   20 +++++++++++---------
 elf/dl-open.c              |    2 +-
 elf/rtld.c                 |   16 +++++++---------
 include/dlfcn.h            |    1 +
 sysdeps/generic/ldsodefs.h |    6 ++----
 6 files changed, 23 insertions(+), 24 deletions(-)

diff --git a/elf/dl-deps.c b/elf/dl-deps.c
index e5b9cdf..1cab2d1 100644
--- a/elf/dl-deps.c
+++ b/elf/dl-deps.c
@@ -62,7 +62,7 @@ openaux (void *a)
 {
   struct openaux_args *args = (struct openaux_args *) a;
 
-  args->aux = _dl_map_object (args->map, args->name, 0,
+  args->aux = _dl_map_object (args->map, args->name,
 			      (args->map->l_type == lt_executable
 			       ? lt_library : args->map->l_type),
 			      args->trace_mode, args->open_mode,
diff --git a/elf/dl-load.c b/elf/dl-load.c
index 776f7e4..9ab3520 100644
--- a/elf/dl-load.c
+++ b/elf/dl-load.c
@@ -1808,7 +1808,7 @@ open_verify (const char *name, struct filebuf *fbp, struct link_map *loader,
    if MAY_FREE_DIRS is true.  */
 
 static int
-open_path (const char *name, size_t namelen, int preloaded,
+open_path (const char *name, size_t namelen, int secure,
 	   struct r_search_path_struct *sps, char **realname,
 	   struct filebuf *fbp, struct link_map *loader, int whatcode,
 	   bool *found_other_class)
@@ -1890,7 +1890,7 @@ open_path (const char *name, size_t namelen, int preloaded,
 	  /* Remember whether we found any existing directory.  */
 	  here_any |= this_dir->status[cnt] != nonexisting;
 
-	  if (fd != -1 && __builtin_expect (preloaded, 0)
+	  if (fd != -1 && __builtin_expect (secure, 0)
 	      && INTUSE(__libc_enable_secure))
 	    {
 	      /* This is an extra security effort to make sure nobody can
@@ -1959,7 +1959,7 @@ open_path (const char *name, size_t namelen, int preloaded,
 
 struct link_map *
 internal_function
-_dl_map_object (struct link_map *loader, const char *name, int preloaded,
+_dl_map_object (struct link_map *loader, const char *name,
 		int type, int trace_mode, int mode, Lmid_t nsid)
 {
   int fd;
@@ -2063,7 +2063,8 @@ _dl_map_object (struct link_map *loader, const char *name, int preloaded,
 	  for (l = loader; l; l = l->l_loader)
 	    if (cache_rpath (l, &l->l_rpath_dirs, DT_RPATH, "RPATH"))
 	      {
-		fd = open_path (name, namelen, preloaded, &l->l_rpath_dirs,
+		fd = open_path (name, namelen, mode & __RTLD_SECURE,
+				&l->l_rpath_dirs,
 				&realname, &fb, loader, LA_SER_RUNPATH,
 				&found_other_class);
 		if (fd != -1)
@@ -2078,14 +2079,15 @@ _dl_map_object (struct link_map *loader, const char *name, int preloaded,
 	      && main_map != NULL && main_map->l_type != lt_loaded
 	      && cache_rpath (main_map, &main_map->l_rpath_dirs, DT_RPATH,
 			      "RPATH"))
-	    fd = open_path (name, namelen, preloaded, &main_map->l_rpath_dirs,
+	    fd = open_path (name, namelen, mode & __RTLD_SECURE,
+			    &main_map->l_rpath_dirs,
 			    &realname, &fb, loader ?: main_map, LA_SER_RUNPATH,
 			    &found_other_class);
 	}
 
       /* Try the LD_LIBRARY_PATH environment variable.  */
       if (fd == -1 && env_path_list.dirs != (void *) -1)
-	fd = open_path (name, namelen, preloaded, &env_path_list,
+	fd = open_path (name, namelen, mode & __RTLD_SECURE, &env_path_list,
 			&realname, &fb,
 			loader ?: GL(dl_ns)[LM_ID_BASE]._ns_loaded,
 			LA_SER_LIBPATH, &found_other_class);
@@ -2094,12 +2096,12 @@ _dl_map_object (struct link_map *loader, const char *name, int preloaded,
       if (fd == -1 && loader != NULL
 	  && cache_rpath (loader, &loader->l_runpath_dirs,
 			  DT_RUNPATH, "RUNPATH"))
-	fd = open_path (name, namelen, preloaded,
+	fd = open_path (name, namelen, mode & __RTLD_SECURE,
 			&loader->l_runpath_dirs, &realname, &fb, loader,
 			LA_SER_RUNPATH, &found_other_class);
 
       if (fd == -1
-	  && (__builtin_expect (! preloaded, 1)
+	  && (__builtin_expect (! (mode & __RTLD_SECURE), 1)
 	      || ! INTUSE(__libc_enable_secure)))
 	{
 	  /* Check the list of libraries in the file /etc/ld.so.cache,
@@ -2165,7 +2167,7 @@ _dl_map_object (struct link_map *loader, const char *name, int preloaded,
 	  && ((l = loader ?: GL(dl_ns)[nsid]._ns_loaded) == NULL
 	      || __builtin_expect (!(l->l_flags_1 & DF_1_NODEFLIB), 1))
 	  && rtld_search_dirs.dirs != (void *) -1)
-	fd = open_path (name, namelen, preloaded, &rtld_search_dirs,
+	fd = open_path (name, namelen, mode & __RTLD_SECURE, &rtld_search_dirs,
 			&realname, &fb, l, LA_SER_DEFAULT, &found_other_class);
 
       /* Add another newline when we are tracing the library loading.  */
diff --git a/elf/dl-open.c b/elf/dl-open.c
index c394b3f..cf8e8cc 100644
--- a/elf/dl-open.c
+++ b/elf/dl-open.c
@@ -223,7 +223,7 @@ dl_open_worker (void *a)
 
   /* Load the named object.  */
   struct link_map *new;
-  args->map = new = _dl_map_object (call_map, file, 0, lt_loaded, 0,
+  args->map = new = _dl_map_object (call_map, file, lt_loaded, 0,
 				    mode | __RTLD_CALLMAP, args->nsid);
 
   /* If the pointer returned is NULL this means the RTLD_NOLOAD flag is
diff --git a/elf/rtld.c b/elf/rtld.c
index 201c9cf..4a8cee8 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -587,7 +587,6 @@ struct map_args
   /* Argument to map_doit.  */
   char *str;
   struct link_map *loader;
-  int is_preloaded;
   int mode;
   /* Return value of map_doit.  */
   struct link_map *map;
@@ -625,16 +624,17 @@ static void
 map_doit (void *a)
 {
   struct map_args *args = (struct map_args *) a;
-  args->map = _dl_map_object (args->loader, args->str,
-			      args->is_preloaded, lt_library, 0, args->mode,
-			      LM_ID_BASE);
+  args->map = _dl_map_object (args->loader, args->str, lt_library, 0,
+			      args->mode, LM_ID_BASE);
 }
 
 static void
 dlmopen_doit (void *a)
 {
   struct dlmopen_args *args = (struct dlmopen_args *) a;
-  args->map = _dl_open (args->fname, RTLD_LAZY | __RTLD_DLOPEN | __RTLD_AUDIT,
+  args->map = _dl_open (args->fname,
+			(RTLD_LAZY | __RTLD_DLOPEN | __RTLD_AUDIT
+			 | __RTLD_SECURE),
 			dl_main, LM_ID_NEWLM, _dl_argc, INTUSE(_dl_argv),
 			__environ);
 }
@@ -804,8 +804,7 @@ do_preload (char *fname, struct link_map *main_map, const char *where)
 
   args.str = fname;
   args.loader = main_map;
-  args.is_preloaded = 1;
-  args.mode = 0;
+  args.mode = __RTLD_SECURE;
 
   unsigned int old_nloaded = GL(dl_ns)[LM_ID_BASE]._ns_nloaded;
 
@@ -1050,7 +1049,6 @@ of this helper program; chances are you did not intend to run this program.\n\
 
 	  args.str = rtld_progname;
 	  args.loader = NULL;
-	  args.is_preloaded = 0;
 	  args.mode = __RTLD_OPENEXEC;
 	  (void) _dl_catch_error (&objname, &err_str, &malloced, map_doit,
 				  &args);
@@ -1062,7 +1060,7 @@ of this helper program; chances are you did not intend to run this program.\n\
       else
 	{
 	  HP_TIMING_NOW (start);
-	  _dl_map_object (NULL, rtld_progname, 0, lt_library, 0,
+	  _dl_map_object (NULL, rtld_progname, lt_library, 0,
 			  __RTLD_OPENEXEC, LM_ID_BASE);
 	  HP_TIMING_NOW (stop);
 
diff --git a/include/dlfcn.h b/include/dlfcn.h
index a67426d..af92483 100644
--- a/include/dlfcn.h
+++ b/include/dlfcn.h
@@ -9,6 +9,7 @@
 #define __RTLD_OPENEXEC	0x20000000
 #define __RTLD_CALLMAP	0x10000000
 #define __RTLD_AUDIT	0x08000000
+#define __RTLD_SECURE	0x04000000 /* Apply additional security checks.  */
 
 #define __LM_ID_CALLER	-2
 
diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
index fcc943b..fa4b6b2 100644
--- a/sysdeps/generic/ldsodefs.h
+++ b/sysdeps/generic/ldsodefs.h
@@ -824,11 +824,9 @@ extern void _dl_receive_error (receiver_fct fct, void (*operate) (void *),
 
 /* Open the shared object NAME and map in its segments.
    LOADER's DT_RPATH is used in searching for NAME.
-   If the object is already opened, returns its existing map.
-   For preloaded shared objects PRELOADED is set to a non-zero
-   value to allow additional security checks.  */
+   If the object is already opened, returns its existing map.  */
 extern struct link_map *_dl_map_object (struct link_map *loader,
-					const char *name, int preloaded,
+					const char *name,
 					int type, int trace_mode, int mode,
 					Lmid_t nsid)
      internal_function attribute_hidden;
-- 
1.7.2.3


-- 
Andreas Schwab, schwab@redhat.com
GPG Key fingerprint = D4E8 DBE3 3813 BB5D FA84  5EC7 45C6 250E 6F00 984E
"And now for something completely different."