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Commit b2e7986f authored by Daniel Kurtz's avatar Daniel Kurtz
Browse files

Revert "arm64: ptrace: allow tracer to skip a system call" 



This reverts commit f459f3db.

To be replaced with arm64 seccomp from mainline v3.19.

Signed-off-by: default avatarDaniel Kurtz <djkurtz@google.com>
parent 27f35948

arch/arm64/include/asm/ptrace.h

+0 −8
Original line number Diff line number Diff line
@@ -72,14 +72,6 @@ 
#define COMPAT_PT_TEXT_ADDR		0x10000

#define COMPAT_PT_DATA_ADDR		0x10004

#define COMPAT_PT_TEXT_END_ADDR		0x10008



/*

 * used to skip a system call when tracer changes its number to -1

 * with ptrace(PTRACE_SET_SYSCALL)

 */

#define RET_SKIP_SYSCALL	-1

#define IS_SKIP_SYSCALL(no)	((int)(no & 0xffffffff) == -1)



#ifndef __ASSEMBLY__



/* sizeof(struct user) for AArch32 */

arch/arm64/kernel/entry.S

+0 −4
Original line number Diff line number Diff line
@@ -25,7 +25,6 @@ 
#include <asm/asm-offsets.h>

#include <asm/errno.h>

#include <asm/esr.h>

#include <asm/ptrace.h>

#include <asm/thread_info.h>

#include <asm/unistd.h>
@@ -672,8 +671,6 @@ __sys_trace: 
	mov	x0, sp

	bl	syscall_trace_enter

	adr	lr, __sys_trace_return		// return address

	cmp	w0, #RET_SKIP_SYSCALL		// skip syscall?

	b.eq	__sys_trace_return_skipped

	uxtw	scno, w0			// syscall number (possibly new)

	mov	x1, sp				// pointer to regs

	cmp	scno, sc_nr			// check upper syscall limit
@@ -687,7 +684,6 @@ __sys_trace: 


__sys_trace_return:

	str	x0, [sp]			// save returned x0

__sys_trace_return_skipped:			// x0 already in regs[0]

	mov	x0, sp

	bl	syscall_trace_exit

	b	ret_to_user

arch/arm64/kernel/ptrace.c

+0 −20
Original line number Diff line number Diff line
@@ -1126,32 +1126,12 @@ static void tracehook_report_syscall(struct pt_regs *regs, 


asmlinkage int syscall_trace_enter(struct pt_regs *regs)

{

	unsigned int saved_syscallno = regs->syscallno;



	if (test_thread_flag(TIF_SYSCALL_TRACE))

		tracehook_report_syscall(regs, PTRACE_SYSCALL_ENTER);



	if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))

		trace_sys_enter(regs, regs->syscallno);



	if (IS_SKIP_SYSCALL(regs->syscallno)) {

		/*

		 * RESTRICTION: we can't modify a return value of user

		 * issued syscall(-1) here. In order to ease this flavor,

		 * we need to treat whatever value in x0 as a return value,

		 * but this might result in a bogus value being returned.

		 */

		/*

		 * NOTE: syscallno may also be set to -1 if fatal signal is

		 * detected in tracehook_report_syscall_entry(), but since

		 * a value set to x0 here is not used in this case, we may

		 * neglect the case.

		 */

		if (!test_thread_flag(TIF_SYSCALL_TRACE) ||

				(IS_SKIP_SYSCALL(saved_syscallno)))

			regs->regs[0] = -ENOSYS;

	}



	audit_syscall_entry(regs->syscallno, regs->orig_x0, regs->regs[1],

			    regs->regs[2], regs->regs[3]);