linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: tip-bot for Joerg Roedel <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: dvlasenk@redhat.com, boris.ostrovsky@oracle.com,
	David.Laight@aculab.com, llong@redhat.com, luto@kernel.org,
	hpa@zytor.com, jroedel@suse.de, peterz@infradead.org,
	pavel@ucw.cz, eduval@amazon.com, aarcange@redhat.com,
	jpoimboe@redhat.com, jgross@suse.com, mingo@kernel.org,
	bp@alien8.de, torvalds@linux-foundation.org, brgerst@gmail.com,
	dhgutteridge@sympatico.ca, linux-kernel@vger.kernel.org,
	will.deacon@arm.com, dave.hansen@intel.com, jkosina@suse.cz,
	tglx@linutronix.de, gregkh@linuxfoundation.org
Subject: [tip:x86/pti] x86/entry/32: Add debug code to check entry/exit CR3
Date: Thu, 19 Jul 2018 16:38:52 -0700	[thread overview]
Message-ID: <tip-97193702c6d353e12aefc0fb2f73a98ca421cd56@git.kernel.org> (raw)
In-Reply-To: <1531906876-13451-40-git-send-email-joro@8bytes.org>

Commit-ID:  97193702c6d353e12aefc0fb2f73a98ca421cd56
Gitweb:     https://git.kernel.org/tip/97193702c6d353e12aefc0fb2f73a98ca421cd56
Author:     Joerg Roedel <jroedel@suse.de>
AuthorDate: Wed, 18 Jul 2018 11:41:16 +0200
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Fri, 20 Jul 2018 01:11:49 +0200

x86/entry/32: Add debug code to check entry/exit CR3

Add code to check whether the kernel is entered and left with the correct
CR3 and make it depend on CONFIG_DEBUG_ENTRY.  This is needed because there
is no NX protection of user-addresses in the kernel-CR3 on x86-32 and that
type of bug would not be detected otherwise.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Pavel Machek <pavel@ucw.cz>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: linux-mm@kvack.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Waiman Long <llong@redhat.com>
Cc: "David H . Gutteridge" <dhgutteridge@sympatico.ca>
Cc: joro@8bytes.org
Link: https://lkml.kernel.org/r/1531906876-13451-40-git-send-email-joro@8bytes.org

---
 arch/x86/entry/entry_32.S | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index b1541c74c71a..010cdb41e3c7 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -166,6 +166,24 @@
 .Lend_\@:
 .endm
 
+.macro BUG_IF_WRONG_CR3 no_user_check=0
+#ifdef CONFIG_DEBUG_ENTRY
+	ALTERNATIVE "jmp .Lend_\@", "", X86_FEATURE_PTI
+	.if \no_user_check == 0
+	/* coming from usermode? */
+	testl	$SEGMENT_RPL_MASK, PT_CS(%esp)
+	jz	.Lend_\@
+	.endif
+	/* On user-cr3? */
+	movl	%cr3, %eax
+	testl	$PTI_SWITCH_MASK, %eax
+	jnz	.Lend_\@
+	/* From userspace with kernel cr3 - BUG */
+	ud2
+.Lend_\@:
+#endif
+.endm
+
 /*
  * Switch to kernel cr3 if not already loaded and return current cr3 in
  * \scratch_reg
@@ -213,6 +231,8 @@
 .macro SAVE_ALL_NMI cr3_reg:req
 	SAVE_ALL
 
+	BUG_IF_WRONG_CR3
+
 	/*
 	 * Now switch the CR3 when PTI is enabled.
 	 *
@@ -224,6 +244,7 @@
 
 .Lend_\@:
 .endm
+
 /*
  * This is a sneaky trick to help the unwinder find pt_regs on the stack.  The
  * frame pointer is replaced with an encoded pointer to pt_regs.  The encoding
@@ -287,6 +308,8 @@
 
 .Lswitched_\@:
 
+	BUG_IF_WRONG_CR3
+
 	RESTORE_REGS pop=\pop
 .endm
 
@@ -357,6 +380,8 @@
 
 	ALTERNATIVE     "", "jmp .Lend_\@", X86_FEATURE_XENPV
 
+	BUG_IF_WRONG_CR3
+
 	SWITCH_TO_KERNEL_CR3 scratch_reg=%eax
 
 	/*
@@ -799,6 +824,7 @@ ENTRY(entry_SYSENTER_32)
 	 */
 	pushfl
 	pushl	%eax
+	BUG_IF_WRONG_CR3 no_user_check=1
 	SWITCH_TO_KERNEL_CR3 scratch_reg=%eax
 	popl	%eax
 	popfl
@@ -893,6 +919,7 @@ ENTRY(entry_SYSENTER_32)
 	 * whereas POPF does not.)
 	 */
 	btrl	$X86_EFLAGS_IF_BIT, (%esp)
+	BUG_IF_WRONG_CR3 no_user_check=1
 	popfl
 	popl	%eax
 
@@ -970,6 +997,8 @@ restore_all:
 	/* Switch back to user CR3 */
 	SWITCH_TO_USER_CR3 scratch_reg=%eax
 
+	BUG_IF_WRONG_CR3
+
 	/* Restore user state */
 	RESTORE_REGS pop=4			# skip orig_eax/error_code
 .Lirq_return:
@@ -983,6 +1012,7 @@ restore_all:
 restore_all_kernel:
 	TRACE_IRQS_IRET
 	PARANOID_EXIT_TO_KERNEL_MODE
+	BUG_IF_WRONG_CR3
 	RESTORE_REGS 4
 	jmp	.Lirq_return
 
@@ -990,6 +1020,19 @@ restore_all_kernel:
 ENTRY(iret_exc	)
 	pushl	$0				# no error code
 	pushl	$do_iret_error
+
+#ifdef CONFIG_DEBUG_ENTRY
+	/*
+	 * The stack-frame here is the one that iret faulted on, so its a
+	 * return-to-user frame. We are on kernel-cr3 because we come here from
+	 * the fixup code. This confuses the CR3 checker, so switch to user-cr3
+	 * as the checker expects it.
+	 */
+	pushl	%eax
+	SWITCH_TO_USER_CR3 scratch_reg=%eax
+	popl	%eax
+#endif
+
 	jmp	common_exception
 .previous
 	_ASM_EXTABLE(.Lirq_return, iret_exc)

  reply	other threads:[~2018-07-19 23:39 UTC|newest]

Thread overview: 96+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-18  9:40 [PATCH 00/39 v8] PTI support for x86-32 Joerg Roedel
2018-07-18  9:40 ` [PATCH 01/39] x86/asm-offsets: Move TSS_sp0 and TSS_sp1 to asm-offsets.c Joerg Roedel
2018-07-19 23:18   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:40 ` [PATCH 02/39] x86/entry/32: Rename TSS_sysenter_sp0 to TSS_entry2task_stack Joerg Roedel
2018-07-19 23:19   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:40 ` [PATCH 03/39] x86/entry/32: Load task stack from x86_tss.sp1 in SYSENTER handler Joerg Roedel
2018-07-19 23:19   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:40 ` [PATCH 04/39] x86/entry/32: Put ESPFIX code into a macro Joerg Roedel
2018-07-19 23:20   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:40 ` [PATCH 05/39] x86/entry/32: Unshare NMI return path Joerg Roedel
2018-07-19 23:21   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:40 ` [PATCH 06/39] x86/entry/32: Split off return-to-kernel path Joerg Roedel
2018-07-19 23:21   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:40 ` [PATCH 07/39] x86/entry/32: Enter the kernel via trampoline stack Joerg Roedel
2018-07-18 18:09   ` Brian Gerst
2018-07-19 20:52     ` Thomas Gleixner
2018-07-19 23:22   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:40 ` [PATCH 08/39] x86/entry/32: Leave " Joerg Roedel
2018-07-19 23:22   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:40 ` [PATCH 09/39] x86/entry/32: Introduce SAVE_ALL_NMI and RESTORE_ALL_NMI Joerg Roedel
2018-07-19 23:23   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:40 ` [PATCH 10/39] x86/entry/32: Handle Entry from Kernel-Mode on Entry-Stack Joerg Roedel
2018-07-19 23:23   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-10-12 18:29   ` [PATCH 10/39] " Jan Kiszka
2018-10-13  9:54     ` [PATCH] x86/entry/32: Fix setup of CS high bits Jan Kiszka
2018-10-13 15:12       ` Andy Lutomirski
2018-10-15 13:08         ` Jan Kiszka
2018-10-15 13:14           ` David Laight
2018-10-15 13:18             ` Jan Kiszka
2018-10-15 13:29               ` David Laight
2018-10-15  9:10       ` Joerg Roedel
2018-10-15 14:09       ` [PATCH v2] " Jan Kiszka
2018-10-15 15:09         ` [tip:x86/urgent] x86/entry/32: Clear the " tip-bot for Jan Kiszka
2018-10-18  6:21         ` tip-bot for Jan Kiszka
2018-07-18  9:40 ` [PATCH 11/39] x86/entry/32: Simplify debug entry point Joerg Roedel
2018-07-19 23:24   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:40 ` [PATCH 12/39] x86/entry/32: Add PTI cr3 switch to non-NMI entry/exit points Joerg Roedel
2018-07-19 23:24   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:40 ` [PATCH 13/39] x86/entry/32: Add PTI cr3 switches to NMI handler code Joerg Roedel
2018-07-19 23:25   ` [tip:x86/pti] x86/entry/32: Add PTI CR3 " tip-bot for Joerg Roedel
2018-07-18  9:40 ` [PATCH 14/39] x86/entry: Rename update_sp0 to update_task_stack Joerg Roedel
2018-07-19 23:25   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:40 ` [PATCH 15/39] x86/pgtable: Rename pti_set_user_pgd to pti_set_user_pgtbl Joerg Roedel
2018-07-19 23:26   ` [tip:x86/pti] x86/pgtable: Rename pti_set_user_pgd() to pti_set_user_pgtbl() tip-bot for Joerg Roedel
2018-07-18  9:40 ` [PATCH 16/39] x86/pgtable/pae: Unshare kernel PMDs when PTI is enabled Joerg Roedel
2018-07-19 23:26   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:40 ` [PATCH 17/39] x86/pgtable/32: Allocate 8k page-tables " Joerg Roedel
2018-07-19 23:27   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:40 ` [PATCH 18/39] x86/pgtable: Move pgdp kernel/user conversion functions to pgtable.h Joerg Roedel
2018-07-19 23:27   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:40 ` [PATCH 19/39] x86/pgtable: Move pti_set_user_pgtbl() " Joerg Roedel
2018-07-19 23:28   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:40 ` [PATCH 20/39] x86/pgtable: Move two more functions from pgtable_64.h " Joerg Roedel
2018-07-19 23:28   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:40 ` [PATCH 21/39] x86/mm/pae: Populate valid user PGD entries Joerg Roedel
2018-07-19 23:29   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:40 ` [PATCH 22/39] x86/mm/pae: Populate the user page-table with user pgd's Joerg Roedel
2018-07-19 23:30   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:41 ` [PATCH 23/39] x86/mm/legacy: " Joerg Roedel
2018-07-19 23:30   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:41 ` [PATCH 24/39] x86/mm/pti: Add an overflow check to pti_clone_pmds() Joerg Roedel
2018-07-19 23:31   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:41 ` [PATCH 25/39] x86/mm/pti: Define X86_CR3_PTI_PCID_USER_BIT on x86_32 Joerg Roedel
2018-07-19 23:31   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:41 ` [PATCH 26/39] x86/mm/pti: Clone CPU_ENTRY_AREA on PMD level " Joerg Roedel
2018-07-19 23:32   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:41 ` [PATCH 27/39] x86/mm/pti: Make pti_clone_kernel_text() compile on 32 bit Joerg Roedel
2018-07-19 23:32   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:41 ` [PATCH 28/39] x86/mm/pti: Keep permissions when cloning kernel text in pti_clone_kernel_text() Joerg Roedel
2018-07-19 23:33   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:41 ` [PATCH 29/39] x86/mm/pti: Introduce pti_finalize() Joerg Roedel
2018-07-19 23:33   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:41 ` [PATCH 30/39] x86/mm/pti: Clone entry-text again in pti_finalize() Joerg Roedel
2018-07-19 23:34   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:41 ` [PATCH 31/39] x86/mm/dump_pagetables: Define INIT_PGD Joerg Roedel
2018-07-19 23:34   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:41 ` [PATCH 32/39] x86/pgtable/pae: Use separate kernel PMDs for user page-table Joerg Roedel
2018-07-19 23:35   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-10-05 14:06   ` [PATCH 32/39] " Arnd Bergmann
2018-07-18  9:41 ` [PATCH 33/39] x86/ldt: Reserve address-space range on 32 bit for the LDT Joerg Roedel
2018-07-19 23:35   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:41 ` [PATCH 34/39] x86/ldt: Define LDT_END_ADDR Joerg Roedel
2018-07-19 23:36   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:41 ` [PATCH 35/39] x86/ldt: Split out sanity check in map_ldt_struct() Joerg Roedel
2018-07-19 23:36   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:41 ` [PATCH 36/39] x86/ldt: Enable LDT user-mapping for PAE Joerg Roedel
2018-07-19 23:37   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:41 ` [PATCH 37/39] x86/pti: Allow CONFIG_PAGE_TABLE_ISOLATION for x86_32 Joerg Roedel
2018-07-19 23:37   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:41 ` [PATCH 38/39] x86/mm/pti: Add Warning when booting on a PCID capable CPU Joerg Roedel
2018-07-19 23:38   ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18  9:41 ` [PATCH 39/39] x86/entry/32: Add debug code to check entry/exit cr3 Joerg Roedel
2018-07-19 23:38   ` tip-bot for Joerg Roedel [this message]
2018-07-18 11:59 ` [PATCH 00/39 v8] PTI support for x86-32 Pavel Machek
2018-07-19 23:21 ` Thomas Gleixner
2018-07-20  7:59   ` Joerg Roedel

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=tip-97193702c6d353e12aefc0fb2f73a98ca421cd56@git.kernel.org \
    --to=tipbot@zytor.com \
    --cc=David.Laight@aculab.com \
    --cc=aarcange@redhat.com \
    --cc=boris.ostrovsky@oracle.com \
    --cc=bp@alien8.de \
    --cc=brgerst@gmail.com \
    --cc=dave.hansen@intel.com \
    --cc=dhgutteridge@sympatico.ca \
    --cc=dvlasenk@redhat.com \
    --cc=eduval@amazon.com \
    --cc=gregkh@linuxfoundation.org \
    --cc=hpa@zytor.com \
    --cc=jgross@suse.com \
    --cc=jkosina@suse.cz \
    --cc=jpoimboe@redhat.com \
    --cc=jroedel@suse.de \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-tip-commits@vger.kernel.org \
    --cc=llong@redhat.com \
    --cc=luto@kernel.org \
    --cc=mingo@kernel.org \
    --cc=pavel@ucw.cz \
    --cc=peterz@infradead.org \
    --cc=tglx@linutronix.de \
    --cc=torvalds@linux-foundation.org \
    --cc=will.deacon@arm.com \
    --subject='Re: [tip:x86/pti] x86/entry/32: Add debug code to check entry/exit CR3' \
    /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

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).