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x86/ioperm: Fix io bitmap invalidation on Xen PV 

tss_invalidate_io_bitmap() wasn't wired up properly through the pvop
machinery, so the TSS and Xen's io bitmap would get out of sync
whenever disabling a valid io bitmap.

Add a new pvop for tss_invalidate_io_bitmap() to fix it.

This is XSA-329.

Fixes: 22fe5b0439 ("x86/ioperm: Move TSS bitmap update to exit to user work")
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/d53075590e1f91c19f8af705059d3ff99424c020.1595030016.git.luto@kernel.org
This commit is contained in:
Andy Lutomirski 2020-07-17 16:53:55 -07:00 committed by Thomas Gleixner
parent 81e96851ea
commit cadfad8701
6 changed files with 38 additions and 17 deletions
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16
arch/x86/include/asm/io_bitmap.h
View File

@ -19,12 +19,28 @@ struct task_struct;
void io_bitmap_share(struct task_struct *tsk);
void io_bitmap_exit(struct task_struct *tsk);
static inline void native_tss_invalidate_io_bitmap(void)
{
/*
* Invalidate the I/O bitmap by moving io_bitmap_base outside the
* TSS limit so any subsequent I/O access from user space will
* trigger a #GP.
*
* This is correct even when VMEXIT rewrites the TSS limit
* to 0x67 as the only requirement is that the base points
* outside the limit.
*/
this_cpu_write(cpu_tss_rw.x86_tss.io_bitmap_base,
IO_BITMAP_OFFSET_INVALID);
}
void native_tss_update_io_bitmap(void);
#ifdef CONFIG_PARAVIRT_XXL
#include <asm/paravirt.h>
#else
#define tss_update_io_bitmap native_tss_update_io_bitmap
#define tss_invalidate_io_bitmap native_tss_invalidate_io_bitmap
#endif
#else

5
arch/x86/include/asm/paravirt.h
View File

@ -302,6 +302,11 @@ static inline void write_idt_entry(gate_desc *dt, int entry, const gate_desc *g)
}
#ifdef CONFIG_X86_IOPL_IOPERM
static inline void tss_invalidate_io_bitmap(void)
{
PVOP_VCALL0(cpu.invalidate_io_bitmap);
}
static inline void tss_update_io_bitmap(void)
{
PVOP_VCALL0(cpu.update_io_bitmap);

1
arch/x86/include/asm/paravirt_types.h
View File

@ -141,6 +141,7 @@ struct pv_cpu_ops {
void (*load_sp0)(unsigned long sp0);
#ifdef CONFIG_X86_IOPL_IOPERM
void (*invalidate_io_bitmap)(void);
void (*update_io_bitmap)(void);
#endif

3
arch/x86/kernel/paravirt.c
View File

@ -324,7 +324,8 @@ struct paravirt_patch_template pv_ops = {
.cpu.swapgs = native_swapgs,
#ifdef CONFIG_X86_IOPL_IOPERM
.cpu.update_io_bitmap = native_tss_update_io_bitmap,
.cpu.invalidate_io_bitmap = native_tss_invalidate_io_bitmap,
.cpu.update_io_bitmap = native_tss_update_io_bitmap,
#endif
.cpu.start_context_switch = paravirt_nop,

18
arch/x86/kernel/process.c
View File

@ -322,20 +322,6 @@ void arch_setup_new_exec(void)
}
#ifdef CONFIG_X86_IOPL_IOPERM
static inline void tss_invalidate_io_bitmap(struct tss_struct *tss)
{
/*
* Invalidate the I/O bitmap by moving io_bitmap_base outside the
* TSS limit so any subsequent I/O access from user space will
* trigger a #GP.
*
* This is correct even when VMEXIT rewrites the TSS limit
* to 0x67 as the only requirement is that the base points
* outside the limit.
*/
tss->x86_tss.io_bitmap_base = IO_BITMAP_OFFSET_INVALID;
}
static inline void switch_to_bitmap(unsigned long tifp)
{
/*
@ -346,7 +332,7 @@ static inline void switch_to_bitmap(unsigned long tifp)
* user mode.
*/
if (tifp & _TIF_IO_BITMAP)
tss_invalidate_io_bitmap(this_cpu_ptr(&cpu_tss_rw));
tss_invalidate_io_bitmap();
}
static void tss_copy_io_bitmap(struct tss_struct *tss, struct io_bitmap *iobm)
@ -380,7 +366,7 @@ void native_tss_update_io_bitmap(void)
u16 *base = &tss->x86_tss.io_bitmap_base;
if (!test_thread_flag(TIF_IO_BITMAP)) {
tss_invalidate_io_bitmap(tss);
native_tss_invalidate_io_bitmap();
return;
}

12
arch/x86/xen/enlighten_pv.c
View File

@ -870,6 +870,17 @@ static void xen_load_sp0(unsigned long sp0)
}
#ifdef CONFIG_X86_IOPL_IOPERM
static void xen_invalidate_io_bitmap(void)
{
struct physdev_set_iobitmap iobitmap = {
.bitmap = 0,
.nr_ports = 0,
};
native_tss_invalidate_io_bitmap();
HYPERVISOR_physdev_op(PHYSDEVOP_set_iobitmap, &iobitmap);
}
static void xen_update_io_bitmap(void)
{
struct physdev_set_iobitmap iobitmap;
@ -1099,6 +1110,7 @@ static const struct pv_cpu_ops xen_cpu_ops __initconst = {
.load_sp0 = xen_load_sp0,
#ifdef CONFIG_X86_IOPL_IOPERM
.invalidate_io_bitmap = xen_invalidate_io_bitmap,
.update_io_bitmap = xen_update_io_bitmap,
#endif
.io_delay = xen_io_delay,