Commit 47058bb5 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Al Viro
Browse files

x86: remove address space overrides using set_fs() 



Stop providing the possibility to override the address space using
set_fs() now that there is no need for that any more.  To properly
handle the TASK_SIZE_MAX checking for 4 vs 5-level page tables on
x86 a new alternative is introduced, which just like the one in
entry_64.S has to use the hardcoded virtual address bits to escape
the fact that TASK_SIZE_MAX isn't actually a constant when 5-level
page tables are enabled.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent a1d826d4

arch/x86/Kconfig

+0 −1
Original line number Diff line number Diff line
@@ -237,7 +237,6 @@ config X86 
	select HAVE_ARCH_KCSAN			if X86_64

	select X86_FEATURE_NAMES		if PROC_FS

	select PROC_PID_ARCH_STATUS		if PROC_FS

	select SET_FS

	imply IMA_SECURE_AND_OR_TRUSTED_BOOT    if EFI



config INSTRUCTION_DECODER

arch/x86/ia32/ia32_aout.c

+0 −1
Original line number Diff line number Diff line
@@ -239,7 +239,6 @@ beyond_if: 
	(regs)->ss = __USER32_DS;

	regs->r8 = regs->r9 = regs->r10 = regs->r11 =

	regs->r12 = regs->r13 = regs->r14 = regs->r15 = 0;

	set_fs(USER_DS);

	return 0;

}

arch/x86/include/asm/processor.h

+1 −10
Original line number Diff line number Diff line
@@ -482,10 +482,6 @@ extern unsigned int fpu_user_xstate_size; 


struct perf_event;



typedef struct {

	unsigned long		seg;

} mm_segment_t;



struct thread_struct {

	/* Cached TLS descriptors: */

	struct desc_struct	tls_array[GDT_ENTRY_TLS_ENTRIES];
@@ -538,8 +534,6 @@ struct thread_struct { 
	 */

	unsigned long		iopl_emul;



	mm_segment_t		addr_limit;



	unsigned int		sig_on_uaccess_err:1;



	/* Floating point and extended processor state */
@@ -785,15 +779,12 @@ static inline void spin_lock_prefetch(const void *x) 
#define INIT_THREAD  {							  \

	.sp0			= TOP_OF_INIT_STACK,			  \

	.sysenter_cs		= __KERNEL_CS,				  \

	.addr_limit		= KERNEL_DS,				  \

}



#define KSTK_ESP(task)		(task_pt_regs(task)->sp)



#else

#define INIT_THREAD  {						\

	.addr_limit		= KERNEL_DS,			\

}

#define INIT_THREAD { }



extern unsigned long KSTK_ESP(struct task_struct *task);

arch/x86/include/asm/thread_info.h

+0 −2
Original line number Diff line number Diff line
@@ -102,7 +102,6 @@ struct thread_info { 
#define TIF_SYSCALL_TRACEPOINT	28	/* syscall tracepoint instrumentation */

#define TIF_ADDR32		29	/* 32-bit address space on 64 bits */

#define TIF_X32			30	/* 32-bit native x86-64 binary */

#define TIF_FSCHECK		31	/* Check FS is USER_DS on return */



#define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)

#define _TIF_NOTIFY_RESUME	(1 << TIF_NOTIFY_RESUME)
@@ -131,7 +130,6 @@ struct thread_info { 
#define _TIF_SYSCALL_TRACEPOINT	(1 << TIF_SYSCALL_TRACEPOINT)

#define _TIF_ADDR32		(1 << TIF_ADDR32)

#define _TIF_X32		(1 << TIF_X32)

#define _TIF_FSCHECK		(1 << TIF_FSCHECK)



/* flags to check in __switch_to() */

#define _TIF_WORK_CTXSW_BASE					\

arch/x86/include/asm/uaccess.h

+1 −25
Original line number Diff line number Diff line
@@ -12,30 +12,6 @@ 
#include <asm/smap.h>

#include <asm/extable.h>



/*

 * The fs value determines whether argument validity checking should be

 * performed or not.  If get_fs() == USER_DS, checking is performed, with

 * get_fs() == KERNEL_DS, checking is bypassed.

 *

 * For historical reasons, these macros are grossly misnamed.

 */



#define MAKE_MM_SEG(s)	((mm_segment_t) { (s) })



#define KERNEL_DS	MAKE_MM_SEG(-1UL)

#define USER_DS 	MAKE_MM_SEG(TASK_SIZE_MAX)



#define get_fs()	(current->thread.addr_limit)

static inline void set_fs(mm_segment_t fs)

{

	current->thread.addr_limit = fs;

	/* On user-mode return, check fs is correct */

	set_thread_flag(TIF_FSCHECK);

}



#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)

#define user_addr_max() (current->thread.addr_limit.seg)



/*

 * Test whether a block of memory is a valid user space address.

 * Returns 0 if the range is valid, nonzero otherwise.
@@ -93,7 +69,7 @@ static inline bool pagefault_disabled(void); 
#define access_ok(addr, size)					\

({									\

	WARN_ON_IN_IRQ();						\

	likely(!__range_not_ok(addr, size, user_addr_max()));		\

	likely(!__range_not_ok(addr, size, TASK_SIZE_MAX));		\

})



/*

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