glibc/sysdeps/x86/link_map.h
H.J. Lu d524fa6c35 Check multiple NT_GNU_PROPERTY_TYPE_0 notes [BZ #23509]
Linkers group input note sections with the same name into one output
note section with the same name.  One output note section is placed in
one PT_NOTE segment.  Since new linkers merge input .note.gnu.property
sections into one output .note.gnu.property section, there is only
one NT_GNU_PROPERTY_TYPE_0 note in one PT_NOTE segment with new linkers.
Since older linkers treat input .note.gnu.property section as a generic
note section and just concatenate all input .note.gnu.property sections
into one output .note.gnu.property section without merging them, we may
see multiple NT_GNU_PROPERTY_TYPE_0 notes in one PT_NOTE segment with
older linkers.

When an older linker is used to created the program on CET-enabled OS,
the linker output has a single .note.gnu.property section with multiple
NT_GNU_PROPERTY_TYPE_0 notes, some of which have IBT and SHSTK enable
bits set even if the program isn't CET enabled.  Such programs will
crash on CET-enabled machines.  This patch updates the note parser:

1. Skip note parsing if a NT_GNU_PROPERTY_TYPE_0 note has been processed.
2. Check multiple NT_GNU_PROPERTY_TYPE_0 notes.

	[BZ #23509]
	* sysdeps/x86/dl-prop.h (_dl_process_cet_property_note): Skip
	note parsing if a NT_GNU_PROPERTY_TYPE_0 note has been processed.
	Update the l_cet field when processing NT_GNU_PROPERTY_TYPE_0 note.
	Check multiple NT_GNU_PROPERTY_TYPE_0 notes.
	* sysdeps/x86/link_map.h (l_cet): Expand to 3 bits,  Add
	lc_unknown.
2018-11-08 10:07:10 -08:00

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C

/* Additional fields in struct link_map. Linux/x86 version.
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/>. */
/* If this object is enabled with CET. */
enum
{
lc_unknown = 0, /* Unknown CET status. */
lc_none = 1 << 0, /* Not enabled with CET. */
lc_ibt = 1 << 1, /* Enabled with IBT. */
lc_shstk = 1 << 2, /* Enabled with STSHK. */
lc_ibt_and_shstk = lc_ibt | lc_shstk /* Enabled with both. */
} l_cet:3;