From: Joerg Roedel <joro@8bytes.org>
To: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>, "H . Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Linus Torvalds <torvalds@linux-foundation.org>,
Andy Lutomirski <luto@kernel.org>,
Dave Hansen <dave.hansen@intel.com>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Juergen Gross <jgross@suse.com>,
Peter Zijlstra <peterz@infradead.org>,
Borislav Petkov <bp@alien8.de>, Jiri Kosina <jkosina@suse.cz>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Brian Gerst <brgerst@gmail.com>,
David Laight <David.Laight@aculab.com>,
Denys Vlasenko <dvlasenk@redhat.com>,
Eduardo Valentin <eduval@amazon.com>,
Greg KH <gregkh@linuxfoundation.org>,
Will Deacon <will.deacon@arm.com>,
aliguori@amazon.com, daniel.gruss@iaik.tugraz.at,
hughd@google.com, keescook@google.com,
Andrea Arcangeli <aarcange@redhat.com>,
Waiman Long <llong@redhat.com>, Pavel Machek <pavel@ucw.cz>,
"David H . Gutteridge" <dhgutteridge@sympatico.ca>,
jroedel@suse.de, joro@8bytes.org
Subject: [PATCH 39/39] x86/entry/32: Add debug code to check entry/exit cr3
Date: Wed, 18 Jul 2018 11:41:16 +0200 [thread overview]
Message-ID: <1531906876-13451-40-git-send-email-joro@8bytes.org> (raw)
In-Reply-To: <1531906876-13451-1-git-send-email-joro@8bytes.org>
From: Joerg Roedel <jroedel@suse.de>
Add code to check whether we enter and leave the kernel with
the correct cr3 and make it depend on CONFIG_DEBUG_ENTRY.
This is needed because we have no NX protection of
user-addresses in the kernel-cr3 on x86-32 and wouldn't
notice that type of bug otherwise.
Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
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 b1541c7..010cdb4 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)
--
2.7.4
next prev parent reply other threads:[~2018-07-18 9:41 UTC|newest]
Thread overview: 99+ 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 ` Joerg Roedel [this message]
2018-07-19 23:38 ` [tip:x86/pti] x86/entry/32: Add debug code to check entry/exit CR3 tip-bot for Joerg Roedel
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
-- strict thread matches above, loose matches on Subject: below --
2018-07-11 11:29 [PATCH 00/39 v7] " Joerg Roedel
2018-07-11 11:29 ` [PATCH 39/39] x86/entry/32: Add debug code to check entry/exit cr3 Joerg Roedel
2018-07-13 17:28 ` Andy Lutomirski
2018-07-14 5:09 ` Joerg Roedel
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