Commit be8f2743 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Ingo Molnar
Browse files

kprobes: Prohibit probing on .entry.text code 



.entry.text is a code area which is used for interrupt/syscall
entries, which includes many sensitive code.
Thus, it is better to prohibit probing on all of such code
instead of a part of that.
Since some symbols are already registered on kprobe blacklist,
this also removes them from the blacklist.

Signed-off-by: default avatarMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: David S. Miller <davem@davemloft.net>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Jonathan Lebon <jlebon@redhat.com>
Cc: Seiji Aguchi <seiji.aguchi@hds.com>
Link: http://lkml.kernel.org/r/20140417081658.26341.57354.stgit@ltc230.yrl.intra.hitachi.co.jp


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 6a5022a5

arch/x86/kernel/entry_32.S

+0 −33
Original line number Diff line number Diff line
@@ -314,10 +314,6 @@ ENTRY(ret_from_kernel_thread) 
	CFI_ENDPROC

ENDPROC(ret_from_kernel_thread)



/*

 * Interrupt exit functions should be protected against kprobes

 */

	.pushsection .kprobes.text, "ax"

/*

 * Return to user mode is not as complex as all this looks,

 * but we want the default path for a system call return to
@@ -372,10 +368,6 @@ need_resched: 
END(resume_kernel)

#endif

	CFI_ENDPROC

/*

 * End of kprobes section

 */

	.popsection



/* SYSENTER_RETURN points to after the "sysenter" instruction in

   the vsyscall page.  See vsyscall-sysentry.S, which defines the symbol.  */
@@ -495,10 +487,6 @@ sysexit_audit: 
	PTGS_TO_GS_EX

ENDPROC(ia32_sysenter_target)



/*

 * syscall stub including irq exit should be protected against kprobes

 */

	.pushsection .kprobes.text, "ax"

	# system call handler stub

ENTRY(system_call)

	RING0_INT_FRAME			# can't unwind into user space anyway
@@ -691,10 +679,6 @@ syscall_badsys: 
	jmp resume_userspace

END(syscall_badsys)

	CFI_ENDPROC

/*

 * End of kprobes section

 */

	.popsection



.macro FIXUP_ESPFIX_STACK

/*
@@ -781,10 +765,6 @@ common_interrupt: 
ENDPROC(common_interrupt)

	CFI_ENDPROC



/*

 *  Irq entries should be protected against kprobes

 */

	.pushsection .kprobes.text, "ax"

#define BUILD_INTERRUPT3(name, nr, fn)	\

ENTRY(name)				\

	RING0_INT_FRAME;		\
@@ -961,10 +941,6 @@ ENTRY(spurious_interrupt_bug) 
	jmp error_code

	CFI_ENDPROC

END(spurious_interrupt_bug)

/*

 * End of kprobes section

 */

	.popsection



#ifdef CONFIG_XEN

/* Xen doesn't set %esp to be precisely what the normal sysenter
@@ -1239,11 +1215,6 @@ return_to_handler: 
	jmp *%ecx

#endif



/*

 * Some functions should be protected against kprobes

 */

	.pushsection .kprobes.text, "ax"



#ifdef CONFIG_TRACING

ENTRY(trace_page_fault)

	RING0_EC_FRAME
@@ -1453,7 +1424,3 @@ ENTRY(async_page_fault) 
END(async_page_fault)

#endif

/*

 * End of kprobes section

 */

	.popsection

arch/x86/kernel/entry_64.S

+0 −20
Original line number Diff line number Diff line
@@ -487,8 +487,6 @@ ENDPROC(native_usergs_sysret64) 
	TRACE_IRQS_OFF

	.endm



/* save complete stack frame */

	.pushsection .kprobes.text, "ax"

ENTRY(save_paranoid)

	XCPT_FRAME 1 RDI+8

	cld
@@ -517,7 +515,6 @@ ENTRY(save_paranoid) 
1:	ret

	CFI_ENDPROC

END(save_paranoid)

	.popsection



/*

 * A newly forked process directly context switches into this address.
@@ -975,10 +972,6 @@ END(interrupt) 
	call \func

	.endm



/*

 * Interrupt entry/exit should be protected against kprobes

 */

	.pushsection .kprobes.text, "ax"

	/*

	 * The interrupt stubs push (~vector+0x80) onto the stack and

	 * then jump to common_interrupt.
@@ -1113,10 +1106,6 @@ ENTRY(retint_kernel) 


	CFI_ENDPROC

END(common_interrupt)

/*

 * End of kprobes section

 */

       .popsection



/*

 * APIC interrupts.
@@ -1477,11 +1466,6 @@ apicinterrupt3 HYPERVISOR_CALLBACK_VECTOR \ 
	hyperv_callback_vector hyperv_vector_handler

#endif /* CONFIG_HYPERV */



/*

 * Some functions should be protected against kprobes

 */

	.pushsection .kprobes.text, "ax"



paranoidzeroentry_ist debug do_debug DEBUG_STACK

paranoidzeroentry_ist int3 do_int3 DEBUG_STACK

paranoiderrorentry stack_segment do_stack_segment
@@ -1898,7 +1882,3 @@ ENTRY(ignore_sysret) 
	CFI_ENDPROC

END(ignore_sysret)

/*

 * End of kprobes section

 */

	.popsection

arch/x86/kernel/kprobes/core.c

+8 −0
Original line number Diff line number Diff line
@@ -1065,6 +1065,14 @@ int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) 
	return 0;

}



bool arch_within_kprobe_blacklist(unsigned long addr)

{

	return  (addr >= (unsigned long)__kprobes_text_start &&

		 addr < (unsigned long)__kprobes_text_end) ||

		(addr >= (unsigned long)__entry_text_start &&

		 addr < (unsigned long)__entry_text_end);

}



int __init arch_init_kprobes(void)

{

	return 0;

include/linux/kprobes.h

+1 −0
Original line number Diff line number Diff line
@@ -265,6 +265,7 @@ extern void arch_disarm_kprobe(struct kprobe *p); 
extern int arch_init_kprobes(void);

extern void show_registers(struct pt_regs *regs);

extern void kprobes_inc_nmissed_count(struct kprobe *p);

extern bool arch_within_kprobe_blacklist(unsigned long addr);



struct kprobe_insn_cache {

	struct mutex mutex;

kernel/kprobes.c

+8 −5
Original line number Diff line number Diff line
@@ -96,9 +96,6 @@ static raw_spinlock_t *kretprobe_table_lock_ptr(unsigned long hash) 
static struct kprobe_blackpoint kprobe_blacklist[] = {

	{"preempt_schedule",},

	{"native_get_debugreg",},

	{"irq_entries_start",},

	{"common_interrupt",},

	{"mcount",},	/* mcount can be called from everywhere */

	{NULL}    /* Terminator */

};
@@ -1324,12 +1321,18 @@ out: 
	return ret;

}



bool __weak arch_within_kprobe_blacklist(unsigned long addr)

{

	/* The __kprobes marked functions and entry code must not be probed */

	return addr >= (unsigned long)__kprobes_text_start &&

	       addr < (unsigned long)__kprobes_text_end;

}



static int __kprobes in_kprobes_functions(unsigned long addr)

{

	struct kprobe_blackpoint *kb;



	if (addr >= (unsigned long)__kprobes_text_start &&

	    addr < (unsigned long)__kprobes_text_end)

	if (arch_within_kprobe_blacklist(addr))

		return -EINVAL;

	/*

	 * If there exists a kprobe_blacklist, verify and

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