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parisc: Fix and enable seccomp filter support

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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: Helge Deller <deller@gmx.de>
Cc: stable@vger.kernel.org # v4.5
This commit is contained in:
Helge Deller 2016-03-30 14:14:31 +02:00
parent 4f4acc9472
commit 910cd32e55
4 changed files with 23 additions and 2 deletions
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1
arch/parisc/Kconfig
View file

@ -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

13
arch/parisc/include/asm/syscall.h
View file

@ -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;

9
arch/parisc/kernel/ptrace.c
View file

@ -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)

2
arch/parisc/kernel/syscall.S
View file

@ -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