4.5-stable review patch. If anyone has any objections, please let me know.
------------------
From: Helge Deller <del...@gmx.de>
commit 910cd32e552ea09caa89cdbe328e468979b030dd upstream.
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 <del...@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
arch/parisc/Kconfig | 1 +
arch/parisc/include/asm/syscall.h | 13 +++++++++++++
arch/parisc/kernel/ptrace.c | 9 +++++++--
arch/parisc/kernel/syscall.S | 2 ++
4 files changed, 23 insertions(+), 2 deletions(-)
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -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
--- a/arch/parisc/include/asm/syscall.h
+++ b/arch/parisc/include/asm/syscall.h
@@ -39,6 +39,19 @@ static inline void syscall_get_arguments
}
}
+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;
--- a/arch/parisc/kernel/ptrace.c
+++ b/arch/parisc/kernel/ptrace.c
@@ -270,7 +270,8 @@ long compat_arch_ptrace(struct task_stru
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_re
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)
--- a/arch/parisc/kernel/syscall.S
+++ b/arch/parisc/kernel/syscall.S
@@ -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
