From: Dave Hansen <dave.hansen@linux.intel.com>
To: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org, dave.hansen@linux.intel.com,
moritz.lipp@iaik.tugraz.at, daniel.gruss@iaik.tugraz.at,
michael.schwarz@iaik.tugraz.at,
richard.fellner@student.tugraz.at, luto@kernel.org,
torvalds@linux-foundation.org, keescook@google.com,
hughd@google.com, x86@kernel.org
Subject: [PATCH 27/30] x86, kaiser: un-poison PGDs at runtime
Date: Wed, 08 Nov 2017 11:47:36 -0800 [thread overview]
Message-ID: <20171108194736.E68E5874@viggo.jf.intel.com> (raw)
In-Reply-To: <20171108194646.907A1942@viggo.jf.intel.com>
From: Dave Hansen <dave.hansen@linux.intel.com>
We poison kernel PGDs that map userspace with the NX bit. This
ensures that if we miss a kernel->user CR3 switch, userspace
crashes instead of running in an unhardened state.
We will need this code in a moment when we turn kaiser on and off
at runtime.
Note that we now need an __ASSEMBLY__ #ifdef since we are now
indirectly including kaiser.h into assembly.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Moritz Lipp <moritz.lipp@iaik.tugraz.at>
Cc: Daniel Gruss <daniel.gruss@iaik.tugraz.at>
Cc: Michael Schwarz <michael.schwarz@iaik.tugraz.at>
Cc: Richard Fellner <richard.fellner@student.tugraz.at>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Kees Cook <keescook@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: x86@kernel.org
---
b/arch/x86/include/asm/pgtable_64.h | 16 ++++++++++++++-
b/arch/x86/mm/kaiser.c | 38 ++++++++++++++++++++++++++++++++++++
b/include/linux/kaiser.h | 3 +-
3 files changed, 55 insertions(+), 2 deletions(-)
diff -puN arch/x86/include/asm/pgtable_64.h~kaiser-dynamic-unpoison-pgd arch/x86/include/asm/pgtable_64.h
--- a/arch/x86/include/asm/pgtable_64.h~kaiser-dynamic-unpoison-pgd 2017-11-08 10:45:40.781681366 -0800
+++ b/arch/x86/include/asm/pgtable_64.h 2017-11-08 10:45:40.788681366 -0800
@@ -2,6 +2,7 @@
#define _ASM_X86_PGTABLE_64_H
#include <linux/const.h>
+#include <linux/kaiser.h>
#include <asm/pgtable_64_types.h>
#ifndef __ASSEMBLY__
@@ -196,6 +197,18 @@ static inline bool pgd_userspace_access(
return (pgd.pgd & _PAGE_USER);
}
+static inline void kaiser_poison_pgd(pgd_t *pgd)
+{
+ if (pgd->pgd & _PAGE_PRESENT)
+ pgd->pgd |= _PAGE_NX;
+}
+
+static inline void kaiser_unpoison_pgd(pgd_t *pgd)
+{
+ if (pgd->pgd & _PAGE_PRESENT)
+ pgd->pgd &= ~_PAGE_NX;
+}
+
/*
* Returns the pgd_t that the kernel should use in its page tables.
*/
@@ -216,7 +229,8 @@ static inline pgd_t kaiser_set_shadow_pg
* wrong CR3 value, userspace will crash
* instead of running.
*/
- pgd.pgd |= _PAGE_NX;
+ if (kaiser_active())
+ kaiser_poison_pgd(&pgd);
}
} else if (!pgd.pgd) {
/*
diff -puN arch/x86/mm/kaiser.c~kaiser-dynamic-unpoison-pgd arch/x86/mm/kaiser.c
--- a/arch/x86/mm/kaiser.c~kaiser-dynamic-unpoison-pgd 2017-11-08 10:45:40.783681366 -0800
+++ b/arch/x86/mm/kaiser.c 2017-11-08 10:45:40.788681366 -0800
@@ -477,6 +477,9 @@ static ssize_t kaiser_enabled_write_file
if (enable > 1)
return -EINVAL;
+ if (kaiser_enabled == enable)
+ return count;
+
WRITE_ONCE(kaiser_enabled, enable);
return count;
}
@@ -494,3 +497,38 @@ static int __init create_kaiser_enabled(
return 0;
}
late_initcall(create_kaiser_enabled);
+
+enum poison {
+ KAISER_POISON,
+ KAISER_UNPOISON
+};
+void kaiser_poison_pgd_page(pgd_t *pgd_page, enum poison do_poison)
+{
+ int i = 0;
+
+ for (i = 0; i < PTRS_PER_PGD; i++) {
+ pgd_t *pgd = &pgd_page[i];
+
+ /* Stop once we hit kernel addresses: */
+ if (!pgdp_maps_userspace(pgd))
+ break;
+
+ if (do_poison == KAISER_POISON)
+ kaiser_poison_pgd(pgd);
+ else
+ kaiser_unpoison_pgd(pgd);
+ }
+
+}
+
+void kaiser_poison_pgds(enum poison do_poison)
+{
+ struct page *page;
+
+ spin_lock(&pgd_lock);
+ list_for_each_entry(page, &pgd_list, lru) {
+ pgd_t *pgd = (pgd_t *)page_address(page);
+ kaiser_poison_pgd_page(pgd, do_poison);
+ }
+ spin_unlock(&pgd_lock);
+}
diff -puN include/linux/kaiser.h~kaiser-dynamic-unpoison-pgd include/linux/kaiser.h
--- a/include/linux/kaiser.h~kaiser-dynamic-unpoison-pgd 2017-11-08 10:45:40.784681366 -0800
+++ b/include/linux/kaiser.h 2017-11-08 10:45:40.788681366 -0800
@@ -4,7 +4,7 @@
#ifdef CONFIG_KAISER
#include <asm/kaiser.h>
#else
-
+#ifndef __ASSEMBLY__
/*
* These stubs are used whenever CONFIG_KAISER is off, which
* includes architectures that support KAISER, but have it
@@ -29,5 +29,6 @@ static inline bool kaiser_active(void)
{
return 0;
}
+#endif /* __ASSEMBLY__ */
#endif /* !CONFIG_KAISER */
#endif /* _INCLUDE_KAISER_H */
_
next prev parent reply other threads:[~2017-11-08 19:47 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-08 19:46 [PATCH 00/30] [v2] KAISER: unmap most of the kernel from userspace page tables Dave Hansen
2017-11-08 19:46 ` [PATCH 01/30] x86, mm: do not set _PAGE_USER for init_mm " Dave Hansen
2017-11-08 19:52 ` Linus Torvalds
2017-11-08 20:11 ` Dave Hansen
2017-11-09 10:29 ` Borislav Petkov
2017-11-08 19:46 ` [PATCH 02/30] x86, tlb: make CR4-based TLB flushes more robust Dave Hansen
2017-11-09 10:48 ` Borislav Petkov
2017-11-09 10:51 ` Thomas Gleixner
2017-11-09 11:02 ` Borislav Petkov
2017-11-08 19:46 ` [PATCH 03/30] x86, mm: document X86_CR4_PGE toggling behavior Dave Hansen
2017-11-09 12:21 ` Borislav Petkov
2017-11-08 19:46 ` [PATCH 04/30] x86, kaiser: disable global pages by default with KAISER Dave Hansen
2017-11-09 12:51 ` Borislav Petkov
2017-11-09 22:19 ` Thomas Gleixner
2017-11-08 19:46 ` [PATCH 05/30] x86, kaiser: prepare assembly for entry/exit CR3 switching Dave Hansen
2017-11-09 13:20 ` Borislav Petkov
2017-11-09 15:34 ` Dave Hansen
2017-11-09 15:59 ` Borislav Petkov
2017-11-08 19:46 ` [PATCH 06/30] x86, kaiser: introduce user-mapped percpu areas Dave Hansen
2017-11-08 19:46 ` [PATCH 07/30] x86, kaiser: mark percpu data structures required for entry/exit Dave Hansen
2017-11-08 19:47 ` [PATCH 08/30] x86, kaiser: unmap kernel from userspace page tables (core patch) Dave Hansen
2017-11-10 12:57 ` Ingo Molnar
2017-11-08 19:47 ` [PATCH 09/30] x86, kaiser: only populate shadow page tables for userspace Dave Hansen
2017-11-08 19:47 ` [PATCH 10/30] x86, kaiser: allow NX to be set in p4d/pgd Dave Hansen
2017-11-08 19:47 ` [PATCH 11/30] x86, kaiser: make sure static PGDs are 8k in size Dave Hansen
2017-11-08 19:47 ` [PATCH 12/30] x86, kaiser: map GDT into user page tables Dave Hansen
2017-11-08 19:47 ` [PATCH 13/30] x86, kaiser: map dynamically-allocated LDTs Dave Hansen
2017-11-08 19:47 ` [PATCH 14/30] x86, kaiser: map espfix structures Dave Hansen
2017-11-08 19:47 ` [PATCH 15/30] x86, kaiser: map entry stack variables Dave Hansen
2017-11-08 19:47 ` [PATCH 16/30] x86, kaiser: map trace interrupt entry Dave Hansen
2017-11-08 19:47 ` [PATCH 17/30] x86, kaiser: map debug IDT tables Dave Hansen
2017-11-08 19:47 ` [PATCH 18/30] x86, kaiser: map virtually-addressed performance monitoring buffers Dave Hansen
2017-11-10 12:17 ` Peter Zijlstra
2017-11-08 19:47 ` [PATCH 19/30] x86, mm: Move CR3 construction functions Dave Hansen
2017-11-08 19:47 ` [PATCH 20/30] x86, mm: remove hard-coded ASID limit checks Dave Hansen
2017-11-10 12:20 ` Peter Zijlstra
2017-11-10 18:41 ` Dave Hansen
2017-11-08 19:47 ` [PATCH 21/30] x86, mm: put mmu-to-h/w ASID translation in one place Dave Hansen
2017-11-08 19:47 ` [PATCH 22/30] x86, pcid, kaiser: allow flushing for future ASID switches Dave Hansen
2017-11-10 12:25 ` Peter Zijlstra
2017-11-08 19:47 ` [PATCH 23/30] x86, kaiser: use PCID feature to make user and kernel switches faster Dave Hansen
2017-11-08 19:47 ` [PATCH 24/30] x86, kaiser: disable native VSYSCALL Dave Hansen
2017-11-09 19:04 ` Andy Lutomirski
2017-11-09 19:26 ` Dave Hansen
2017-11-10 0:53 ` Andy Lutomirski
2017-11-10 0:57 ` Dave Hansen
2017-11-10 1:04 ` Andy Lutomirski
2017-11-10 1:22 ` Dave Hansen
2017-11-10 2:25 ` Andy Lutomirski
2017-11-10 6:31 ` Dave Hansen
2017-11-10 22:06 ` Andy Lutomirski
2017-11-10 23:04 ` Dave Hansen
2017-11-13 3:52 ` Andy Lutomirski
2017-11-13 21:07 ` Dave Hansen
2017-11-14 2:15 ` Andy Lutomirski
2017-11-08 19:47 ` [PATCH 25/30] x86, kaiser: add debugfs file to turn KAISER on/off at runtime Dave Hansen
2017-11-08 19:47 ` [PATCH 26/30] x86, kaiser: add a function to check for KAISER being enabled Dave Hansen
2017-11-08 19:47 ` Dave Hansen [this message]
2017-11-08 19:47 ` [PATCH 28/30] x86, kaiser: allow KAISER to be enabled/disabled at runtime Dave Hansen
2017-11-08 19:47 ` [PATCH 29/30] x86, kaiser: add Kconfig Dave Hansen
2017-11-08 19:47 ` [PATCH 30/30] x86, kaiser, xen: Dynamically disable KAISER when running under Xen PV Dave Hansen
2017-11-09 15:01 ` Juergen Gross
2017-11-10 19:30 [PATCH 00/30] [v3] KAISER: unmap most of the kernel from userspace page tables Dave Hansen
2017-11-10 19:31 ` [PATCH 27/30] x86, kaiser: un-poison PGDs at runtime Dave Hansen
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20171108194736.E68E5874@viggo.jf.intel.com \
--to=dave.hansen@linux.intel.com \
--cc=daniel.gruss@iaik.tugraz.at \
--cc=hughd@google.com \
--cc=keescook@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=luto@kernel.org \
--cc=michael.schwarz@iaik.tugraz.at \
--cc=moritz.lipp@iaik.tugraz.at \
--cc=richard.fellner@student.tugraz.at \
--cc=torvalds@linux-foundation.org \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).