x86/CET: Fix property note parser [BZ #23467]

GNU_PROPERTY_X86_FEATURE_1_AND may not be the first property item.  We
need to check each property item until we reach the end of the property
or find GNU_PROPERTY_X86_FEATURE_1_AND.

This patch adds 2 tests.  The first test checks if IBT is enabled and
the second test reads the output from the first test to check if IBT
is is enabled.  The second second test fails if IBT isn't enabled
properly.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>

	[BZ #23467]
	* sysdeps/unix/sysv/linux/x86/Makefile (tests): Add
	tst-cet-property-1 and tst-cet-property-2 if CET is enabled.
	(CFLAGS-tst-cet-property-1.o): New.
	(ASFLAGS-tst-cet-property-dep-2.o): Likewise.
	($(objpfx)tst-cet-property-2): Likewise.
	($(objpfx)tst-cet-property-2.out): Likewise.
	* sysdeps/unix/sysv/linux/x86/tst-cet-property-1.c: New file.
	* sysdeps/unix/sysv/linux/x86/tst-cet-property-2.c: Likewise.
	* sysdeps/unix/sysv/linux/x86/tst-cet-property-dep-2.S: Likewise.
	* sysdeps/x86/dl-prop.h (_dl_process_cet_property_note): Parse
	each property item until GNU_PROPERTY_X86_FEATURE_1_AND is found.

1 files changed, 63 insertions, 0 deletions

diff --git a/sysdeps/unix/sysv/linux/x86/tst-cet-property-dep-2.S b/sysdeps/unix/sysv/linux/x86/tst-cet-property-dep-2.S
new file mode 100644
index 0000000000..5f5cad34d9
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/x86/tst-cet-property-dep-2.S
@@ -0,0 +1,63 @@
+/* Test CET property note parser.
+   Copyright (C) 2018 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 Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <cet.h>
+
+	.text
+	.p2align 4,,15
+	.globl	bar
+	.type	bar, @function
+/* Since this function doesn't start with ENDBR, it should lead to the
+   IBT violation when called indirectly.  */
+bar:
+	.cfi_startproc
+	ret
+	.cfi_endproc
+	.size	bar, .-bar
+
+#if __SIZEOF_PTRDIFF_T__  == 8
+# define ALIGN 3
+#elif __SIZEOF_PTRDIFF_T__  == 4
+# define ALIGN 2
+#endif
+
+/* In NT_GNU_PROPERTY_TYPE_0 note, add a GNU_PROPERTY_STACK_SIZE property
+   before the GNU_PROPERTY_X86_FEATURE_1_AND property.  */
+	.section ".note.gnu.property", "a"
+	.p2align ALIGN
+	.long 1f - 0f		/* name length */
+	.long 5f - 2f		/* data length */
+	.long 5			/* note type */
+0:	.asciz "GNU"		/* vendor name */
+1:
+	.p2align ALIGN
+2:
+	.long 1			/* pr_type.  */
+	.long 4f - 3f		/* pr_datasz.  */
+3:
+#if __SIZEOF_PTRDIFF_T__  == 8
+	.long 0x800
+	.long 0x800
+#else
+	.long 0x08000800
+#endif
+4:
+	.p2align ALIGN
+5:
+
+	.section	.note.GNU-stack,"",@progbits