Messages in this thread | | | Date | Wed, 9 Jul 2014 12:12:39 +0100 | From | Will Deacon <> | Subject | Re: [RESEND PATCH v4 2/2] arm64: Add seccomp support |
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Hi Akashi,
On Fri, Jul 04, 2014 at 08:31:55AM +0100, AKASHI Takahiro wrote: > secure_computing() should always be called first in syscall_trace_enter(). > If it returns non-zero, we should stop further handling. Then that system > call may eventually fail, be trapped or the process itself be killed > depending on loaded rules. > In this case, syscall_trace_enter() returns a dedicated value in order to > skip a normal syscall table lookup because a seccomp rule may have already > overridden errno.
[...]
> diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c > index 70526cf..baab5fc 100644 > --- a/arch/arm64/kernel/ptrace.c > +++ b/arch/arm64/kernel/ptrace.c > @@ -21,12 +21,14 @@ > > #include <linux/audit.h> > #include <linux/compat.h> > +#include <linux/errno.h> > #include <linux/kernel.h> > #include <linux/sched.h> > #include <linux/mm.h> > #include <linux/smp.h> > #include <linux/ptrace.h> > #include <linux/user.h> > +#include <linux/seccomp.h> > #include <linux/security.h> > #include <linux/init.h> > #include <linux/signal.h> > @@ -1109,6 +1111,10 @@ static void tracehook_report_syscall(struct pt_regs *regs, > > asmlinkage int syscall_trace_enter(struct pt_regs *regs) > { > + if (secure_computing(regs->syscallno) == -1) > + /* seccomp failures shouldn't expose any additional code. */ > + return -EPERM; > + > if (test_thread_flag(TIF_SYSCALL_TRACE)) > tracehook_report_syscall(regs, PTRACE_SYSCALL_ENTER);
We return regs->syscallno immediately after this, so we have the same issue that Kees identified for arch/arm/. Did you follow the discussion I had with Andy?
Will
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