2003-06-26 Roland McGrath <roland@redhat.com>

* elf/elf.h (AT_SECURE): New macro.
	* sysdeps/generic/dl-sysdep.c (_dl_sysdep_start): Grok it,
	set __libc_enable_secure.
	(_dl_show_auxv): Add AT_SECURE to name table.
	* elf/dl-support.c (_dl_aux_init): Grok AT_SECURE, set
	__libc_enable_secure and __libc_enable_secure_decided.
	* sysdeps/unix/sysv/linux/ldsodefs.h
	[__ASSUME_AT_SECURE] (HAVE_AUX_SECURE): Define it.
	* sysdeps/unix/sysv/linux/kernel-features.h
	[__LINUX_KERNEL_VERSION >= 132425] (__ASSUME_AT_SECURE): Define it.

elf/dl-support.c

@@ -188,6 +188,11 @@ _dl_aux_init (ElfW(auxv_t) *av)
 	gid ^= av->a_un.a_val;
 	seen |= 8;
 	break;
+      case AT_SECURE:
+	seen = -1;
+	__libc_enable_secure = av->a_un.a_val;
+	__libc_enable_secure_decided = 1;
+	break;
       }
   if (seen == 0xf)
     {

elf/elf.h

@@ -945,7 +945,9 @@ typedef struct
 
 /* A special ignored value for PPC, used by the kernel to control the
    interpretation of the AUXV. Must be > 16.  */
-#define AT_IGNOREPPC	22		/* Entry should be ignored */
+#define AT_IGNOREPPC	22		/* Entry should be ignored.  */
+
+#define	AT_SECURE	23		/* Boolean, was exec setuid-like?  */
 
 /* Pointer to the global system page used for system calls and other
    nice things.  */

sysdeps/generic/dl-sysdep.c

@@ -79,14 +79,19 @@ _dl_sysdep_start (void **start_argptr,
   ElfW(Word) phnum = 0;
   ElfW(Addr) user_entry;
   ElfW(auxv_t) *av;
+#ifdef HAVE_AUX_SECURE
+# define set_seen_secure() ((void) 0)
+#else
   uid_t uid = 0;
   gid_t gid = 0;
-#ifdef HAVE_AUX_XID
-# define set_seen(tag) (tag) /* Evaluate for the side effects.  */
-#else
   unsigned int seen = 0;
-# define M(type) (1 << (type))
+# define set_seen_secure() (seen = -1)
-# define set_seen(tag) seen |= M ((tag)->a_type)
+# ifdef HAVE_AUX_XID
+#  define set_seen(tag) (tag)	/* Evaluate for the side effects.  */
+# else
+#  define M(type) (1 << (type))
+#  define set_seen(tag) seen |= M ((tag)->a_type)
+# endif
 #endif
 
   DL_FIND_ARG_COMPONENTS (start_argptr, _dl_argc, INTUSE(_dl_argv), _environ,
@@ -123,6 +128,10 @@ _dl_sysdep_start (void **start_argptr,
       case AT_EGID:
 	gid ^= av->a_un.a_val;
 	break;
+      case AT_SECURE:
+	seen = -1;
+	INTUSE(__libc_enable_secure) = av->a_un.a_val;
+	break;
       case AT_PLATFORM:
 	GL(dl_platform) = av->a_un.a_ptr;
 	break;
@@ -152,20 +161,25 @@ _dl_sysdep_start (void **start_argptr,
   DL_SYSDEP_OSCHECK (dl_fatal);
 #endif
 
-  /* Fill in the values we have not gotten from the kernel through the
+#ifndef HAVE_AUX_SECURE
-     auxiliary vector.  */
+  if (seen != -1)
-#ifndef HAVE_AUX_XID
+    {
+      /* Fill in the values we have not gotten from the kernel through the
+	 auxiliary vector.  */
+# ifndef HAVE_AUX_XID
 # define SEE(UID, var, uid) \
    if ((seen & M (AT_##UID)) == 0) var ^= __get##uid ()
-  SEE (UID, uid, uid);
+      SEE (UID, uid, uid);
-  SEE (EUID, uid, euid);
+      SEE (EUID, uid, euid);
-  SEE (GID, gid, gid);
+      SEE (GID, gid, gid);
-  SEE (EGID, gid, egid);
+      SEE (EGID, gid, egid);
-#endif
+# endif
 
-  /* If one of the two pairs of IDs does not match this is a setuid
+      /* If one of the two pairs of IDs does not match this is a setuid
-     or setgid run.  */
+	 or setgid run.  */
-  INTUSE(__libc_enable_secure) = uid | gid;
+      INTUSE(__libc_enable_secure) = uid | gid;
+    }
+#endif
 
 #ifndef HAVE_AUX_PAGESIZE
   if (GL(dl_pagesize) == 0)
@@ -253,8 +267,9 @@ _dl_show_auxv (void)
 	  [AT_UCACHEBSIZE - 2] =	{ "AT_UCACHEBSIZE:  0x", hex },
 #ifdef NEED_DL_SYSINFO
 	  [AT_SYSINFO - 2] =		{ "AT_SYSINFO:      0x", hex },
-	  [AT_SYSINFO_EHDR - 2] =	{ "AT_SYSINFO_EHDR: 0x", hex }
+	  [AT_SYSINFO_EHDR - 2] =	{ "AT_SYSINFO_EHDR: 0x", hex },
 #endif
+	  [AT_SECURE - 2] =		{ "AT_SECURE:       ", dec },
 	};
       unsigned int idx = (unsigned int) (av->a_type - 2);
 

sysdeps/unix/sysv/linux/kernel-features.h

@@ -321,3 +321,9 @@
 #if __LINUX_KERNEL_VERSION >= 132426
 # define __ASSUME_STATFS64	1
 #endif
+
+/* Starting with at least 2.5.74 the kernel passes the setuid-like exec
+   flag unconditionally up to the child.  */
+#if __LINUX_KERNEL_VERSION >= 132426
+# define __ASSUME_AT_SECURE	1
+#endif

sysdeps/unix/sysv/linux/ldsodefs.h

@@ -1,5 +1,5 @@
 /* Run-time dynamic linker data structures for loaded ELF shared objects.
-   Copyright (C) 2001, 2002 Free Software Foundation, Inc.
+   Copyright (C) 2001, 2002, 2003 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
@@ -41,6 +41,12 @@ extern void _dl_non_dynamic_init (void) internal_function;
 # define HAVE_AUX_XID
 #endif
 
+/* We can assume that the kernel always provides the AT_SECURE value
+   in the auxiliary vector from 2.5.74 or so on.  */
+#if __ASSUME_AT_SECURE
+# define HAVE_AUX_SECURE
+#endif
+
 /* Starting with one of the 2.4.0 pre-releases the Linux kernel passes
    up the page size information.  */
 #if __ASSUME_AT_PAGESIZE