On Tue, Jan 13, 2015 at 3:21 PM, Roman Peniaev <[email protected]> wrote: > On Wed, Jan 14, 2015 at 5:08 AM, Kees Cook <[email protected]> wrote: >> On Sun, Jan 11, 2015 at 6:32 AM, Roman Pen <[email protected]> wrote: >>> In previous patch current_thread_info()->syscall is set with >>> corresponding syscall number prior to further calls, thus there >>> is no any need to pass 'scno'. >>> >>> Also, add explicit comment why do we have to reread 'scno' local >>> variable. >>> >>> Signed-off-by: Roman Pen <[email protected]> >>> Cc: Russell King <[email protected]> >>> Cc: Christoffer Dall <[email protected]> >>> Cc: Stefano Stabellini <[email protected]> >>> Cc: Sekhar Nori <[email protected]> >>> Cc: Kees Cook <[email protected]> >>> Cc: Andy Lutomirski <[email protected]> >>> Cc: Eric Paris <[email protected]> >>> Cc: Will Deacon <[email protected]> >>> Cc: [email protected] >>> Cc: [email protected] >>> --- >>> arch/arm/kernel/entry-common.S | 1 - >>> arch/arm/kernel/ptrace.c | 6 ++++-- >>> 2 files changed, 4 insertions(+), 3 deletions(-) >>> >>> diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S >>> index 89452ff..3d12eb5 100644 >>> --- a/arch/arm/kernel/entry-common.S >>> +++ b/arch/arm/kernel/entry-common.S >>> @@ -228,7 +228,6 @@ ENDPROC(vector_swi) >>> * context switches, and waiting for our parent to respond. >>> */ >>> __sys_trace: >>> - mov r1, scno >>> add r0, sp, #S_OFF >>> bl syscall_trace_enter >>> >>> diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c >>> index ef9119f..1238787 100644 >>> --- a/arch/arm/kernel/ptrace.c >>> +++ b/arch/arm/kernel/ptrace.c >>> @@ -928,9 +928,9 @@ static void tracehook_report_syscall(struct pt_regs >>> *regs, >>> regs->ARM_ip = ip; >>> } >>> >>> -asmlinkage int syscall_trace_enter(struct pt_regs *regs, int scno) >>> +asmlinkage int syscall_trace_enter(struct pt_regs *regs) >>> { >>> - current_thread_info()->syscall = scno; >>> + int scno = current_thread_info()->syscall; >> >> Was this assignment of current_thread_info()->syscall redundant? If >> so, this looks fine. If not, what will now be setting the thread_info? > > [sorry, i have to resend this email because previously I sent it using my > phone > and arm maillist rejected it because of html inside] > > Yes, it is redundant. > Because of the previous patch thread_info->syscall already contains > corresponding scnr, > so we use it instead of passing the same number from asm.
Ah! Okay, I wasn't CCed on the 1/2 patch. I see it now, thanks! > So everything should work fine without current patch, and also current > patch should not > change anything in the expected behavior. Great. If this still passes the seccomp testsuite, I'm fine for it. I can test it later this week if no one else gets to it. Reviewed-by: Kees Cook <[email protected]> Thanks! -Kees > > -- > Roman > > > > >> >> -Kees >> >>> >>> /* Do the secure computing check first; failures should be fast. */ >>> #ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER >>> @@ -944,6 +944,8 @@ asmlinkage int syscall_trace_enter(struct pt_regs >>> *regs, int scno) >>> if (test_thread_flag(TIF_SYSCALL_TRACE)) >>> tracehook_report_syscall(regs, PTRACE_SYSCALL_ENTER); >>> >>> + /* Syscall can be aborted (-1 can be set) or even changed >>> + * by the tracer and subsequent PTRACE_SET_SYSCALL request */ >>> scno = current_thread_info()->syscall; >>> >>> if (test_thread_flag(TIF_SYSCALL_TRACEPOINT)) >>> -- >>> 2.1.3 >>> >> >> >> >> -- >> Kees Cook >> Chrome OS Security -- Kees Cook Chrome OS Security -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
