The following commit has been merged into the x86/urgent branch of tip:

Commit-ID: cadfad870154e14f745ec845708bc17d166065f2 Gitweb: https://git.kernel.org/tip/cadfad870154e14f745ec845708bc17d166065f2 Author: Andy Lutomirski luto@kernel.org AuthorDate: Fri, 17 Jul 2020 16:53:55 -07:00 Committer: Thomas Gleixner tglx@linutronix.de CommitterDate: Sat, 18 Jul 2020 12:31:49 +02:00

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: 22fe5b0439dd ("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/d53075590e1f91c19f8af705059d3ff99424c020.159503001...

--- arch/x86/include/asm/io_bitmap.h | 16 ++++++++++++++++ arch/x86/include/asm/paravirt.h | 5 +++++ arch/x86/include/asm/paravirt_types.h | 1 + arch/x86/kernel/paravirt.c | 3 ++- arch/x86/kernel/process.c | 18 ++---------------- arch/x86/xen/enlighten_pv.c | 12 ++++++++++++ 6 files changed, 38 insertions(+), 17 deletions(-)

diff --git a/arch/x86/include/asm/io_bitmap.h b/arch/x86/include/asm/io_bitmap.h index ac1a99f..7f080f5 100644 --- a/arch/x86/include/asm/io_bitmap.h +++ b/arch/x86/include/asm/io_bitmap.h @@ -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 diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h index 5ca5d29..3d2afec 100644 --- a/arch/x86/include/asm/paravirt.h +++ b/arch/x86/include/asm/paravirt.h @@ -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); diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h index 732f62e..8dfcb25 100644 --- a/arch/x86/include/asm/paravirt_types.h +++ b/arch/x86/include/asm/paravirt_types.h @@ -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

diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c index 674a7d6..de2138b 100644 --- a/arch/x86/kernel/paravirt.c +++ b/arch/x86/kernel/paravirt.c @@ -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, diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index f362ce0..fe67dbd 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -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; }

diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c index 0d68948..c46b9f2 100644 --- a/arch/x86/xen/enlighten_pv.c +++ b/arch/x86/xen/enlighten_pv.c @@ -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,