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Date: Thu, 10 Jul 2014 06:33:50 +0200 From: AKASHI Takahiro <takahiro.akashi@...aro.org> To: Will Deacon <will.deacon@....com> CC: "wad@...omium.org" <wad@...omium.org>, Catalin Marinas <Catalin.Marinas@....com>, "dsaxena@...aro.org" <dsaxena@...aro.org>, "linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>, "linaro-kernel@...ts.linaro.org" <linaro-kernel@...ts.linaro.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org> Subject: Re: [RESEND PATCH v4 2/2] arm64: Add seccomp support Will, > (1) Updating syscallno based on w8, but this ties us to the current ABI > and could get messy if this register changes in the future. So, is this the conclusion that I should follow? -Takahiro AKASHI On 07/09/2014 01:12 PM, Will Deacon wrote: > 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 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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