# http://seclists.org/fulldisclosure/2010/Oct/257
# http://sourceware.org/ml/libc-hacker/2010-10/msg00007.html

Path elements containing $ORIGIN should always be ignored in privileged
programs.

Andreas.

2010-10-18  Andreas Schwab  <schwab@redhat.com>

	* elf/dl-load.c (is_dst): Remove last parameter.
	(_dl_dst_count): Ignore $ORIGIN in privileged programs.
	(_dl_dst_substitute): Likewise.
---
 elf/dl-load.c |   30 +++++++++++++-----------------
 1 files changed, 13 insertions(+), 17 deletions(-)

diff --git a/elf/dl-load.c b/elf/dl-load.c
index a7162eb..776f7e4 100644
--- a/elf/dl-load.c
+++ b/elf/dl-load.c
@@ -169,8 +169,7 @@ local_strdup (const char *s)
 
 
 static size_t
-is_dst (const char *start, const char *name, const char *str,
-	int is_path, int secure)
+is_dst (const char *start, const char *name, const char *str, int is_path)
 {
   size_t len;
   bool is_curly = false;
@@ -199,11 +198,6 @@ is_dst (const char *start, const char *name, const char *str,
 	   && (!is_path || name[len] != ':'))
     return 0;
 
-  if (__builtin_expect (secure, 0)
-      && ((name[len] != '\0' && (!is_path || name[len] != ':'))
-	  || (name != start + 1 && (!is_path || name[-2] != ':'))))
-    return 0;
-
   return len;
 }
 
@@ -218,13 +212,12 @@ _dl_dst_count (const char *name, int is_path)
     {
       size_t len;
 
-      /* $ORIGIN is not expanded for SUID/GUID programs (except if it
-	 is $ORIGIN alone) and it must always appear first in path.  */
+      /* $ORIGIN is not expanded for SUID/GUID programs.  */
       ++name;
-      if ((len = is_dst (start, name, "ORIGIN", is_path,
-			 INTUSE(__libc_enable_secure))) != 0
-	  || (len = is_dst (start, name, "PLATFORM", is_path, 0)) != 0
-	  || (len = is_dst (start, name, "LIB", is_path, 0)) != 0)
+      if (((len = is_dst (start, name, "ORIGIN", is_path)) != 0
+	   && !INTUSE(__libc_enable_secure))
+	  || (len = is_dst (start, name, "PLATFORM", is_path)) != 0
+	  || (len = is_dst (start, name, "LIB", is_path)) != 0)
 	++cnt;
 
       name = strchr (name + len, '$');
@@ -256,9 +249,12 @@ _dl_dst_substitute (struct link_map *l, const char *name, char *result,
 	  size_t len;
 
 	  ++name;
-	  if ((len = is_dst (start, name, "ORIGIN", is_path,
-			     INTUSE(__libc_enable_secure))) != 0)
+	  if ((len = is_dst (start, name, "ORIGIN", is_path)) != 0)
 	    {
+	      /* Ignore this path element in SUID/SGID programs.  */
+	      if (INTUSE(__libc_enable_secure))
+		repl = (const char *) -1;
+	      else
 #ifndef SHARED
 	      if (l == NULL)
 		repl = _dl_get_origin ();
@@ -266,9 +262,9 @@ _dl_dst_substitute (struct link_map *l, const char *name, char *result,
 #endif
 		repl = l->l_origin;
 	    }
-	  else if ((len = is_dst (start, name, "PLATFORM", is_path, 0)) != 0)
+	  else if ((len = is_dst (start, name, "PLATFORM", is_path)) != 0)
 	    repl = GLRO(dl_platform);
-	  else if ((len = is_dst (start, name, "LIB", is_path, 0)) != 0)
+	  else if ((len = is_dst (start, name, "LIB", is_path)) != 0)
 	    repl = DL_DST_LIB;
 
 	  if (repl != NULL && repl != (const char *) -1)
-- 
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."