Commit 910cd32e authored by Helge Deller's avatar Helge Deller
Browse files

parisc: Fix and enable seccomp filter support 



The seccomp filter support requires careful handling of task registers.  This
includes reloading of the return value (%r28) and proper syscall exit if
secure_computing() returned -1.

Additionally we need to sign-extend the syscall number from signed 32bit to
signed 64bit in do_syscall_trace_enter() since the ptrace interface only allows
storing 32bit values in compat mode.

Signed-off-by: default avatarHelge Deller <deller@gmx.de>
Cc: stable@vger.kernel.org # v4.5
parent 4f4acc94

arch/parisc/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -29,6 +29,7 @@ config PARISC 
	select TTY # Needed for pdc_cons.c

	select HAVE_DEBUG_STACKOVERFLOW

	select HAVE_ARCH_AUDITSYSCALL

	select HAVE_ARCH_SECCOMP_FILTER

	select ARCH_NO_COHERENT_DMA_MMAP



	help

arch/parisc/include/asm/syscall.h

+13 −0
Original line number Diff line number Diff line
@@ -39,6 +39,19 @@ static inline void syscall_get_arguments(struct task_struct *tsk, 
	}

}



static inline void syscall_set_return_value(struct task_struct *task,

					    struct pt_regs *regs,

					    int error, long val)

{

	regs->gr[28] = error ? error : val;

}



static inline void syscall_rollback(struct task_struct *task,

				    struct pt_regs *regs)

{

	/* do nothing */

}



static inline int syscall_get_arch(void)

{

	int arch = AUDIT_ARCH_PARISC;

arch/parisc/kernel/ptrace.c

+7 −2
Original line number Diff line number Diff line
@@ -270,7 +270,8 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request, 
long do_syscall_trace_enter(struct pt_regs *regs)

{

	/* Do the secure computing check first. */

	secure_computing_strict(regs->gr[20]);

	if (secure_computing() == -1)

		return -1;



	if (test_thread_flag(TIF_SYSCALL_TRACE) &&

	    tracehook_report_syscall_entry(regs)) {
@@ -296,7 +297,11 @@ long do_syscall_trace_enter(struct pt_regs *regs) 
			regs->gr[23] & 0xffffffff);



out:

	return regs->gr[20];

	/*

	 * Sign extend the syscall number to 64bit since it may have been

	 * modified by a compat ptrace call

	 */

	return (int) ((u32) regs->gr[20]);

}



void do_syscall_trace_exit(struct pt_regs *regs)

arch/parisc/kernel/syscall.S

+2 −0
Original line number Diff line number Diff line
@@ -329,6 +329,7 @@ tracesys_next: 


	ldo     -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1      /* get task ptr */

	LDREG	TI_TASK(%r1), %r1

	LDREG   TASK_PT_GR28(%r1), %r28		/* Restore return value */

	LDREG   TASK_PT_GR26(%r1), %r26		/* Restore the users args */

	LDREG   TASK_PT_GR25(%r1), %r25

	LDREG   TASK_PT_GR24(%r1), %r24
@@ -342,6 +343,7 @@ tracesys_next: 
	stw     %r21, -56(%r30)                 /* 6th argument */

#endif



	cmpib,COND(=),n -1,%r20,tracesys_exit /* seccomp may have returned -1 */

	comiclr,>>=	__NR_Linux_syscalls, %r20, %r0

	b,n	.Ltracesys_nosys

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