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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id c125sm6455272pfa.119.2020.07.10.09.04.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 10 Jul 2020 09:04:09 -0700 (PDT) Date: Fri, 10 Jul 2020 09:04:08 -0700 From: Kees Cook To: Will Deacon Subject: Re: [PATCH v3 6/7] arm64: ptrace: Use NO_SYSCALL instead of -1 in syscall_trace_enter() Message-ID: <202007100902.425E50F4D1@keescook> References: <20200710130702.30658-1-will@kernel.org> <20200710130702.30658-7-will@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200710130702.30658-7-will@kernel.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200710_120412_697327_AEF77DC4 X-CRM114-Status: GOOD ( 19.15 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Luis Machado , catalin.marinas@arm.com, Keno Fischer , kernel-team@android.com, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Jul 10, 2020 at 02:07:01PM +0100, Will Deacon wrote: > Setting a system call number of -1 is special, as it indicates that the > current system call should be skipped. > > Use NO_SYSCALL instead of -1 when checking for this scenario, which is > different from the -1 returned due to a seccomp failure. I can't understand this paragraph. NO_SYSCALL is -1, so how is this "different"? arch/arm64/include/asm/ptrace.h:#define NO_SYSCALL (-1) Do you just mean "stop using a literal '-1'"? -Kees > > Cc: Mark Rutland > Cc: Keno Fischer > Cc: Luis Machado > Signed-off-by: Will Deacon > --- > arch/arm64/kernel/ptrace.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c > index 89fbee3991a2..1e02e98e68dd 100644 > --- a/arch/arm64/kernel/ptrace.c > +++ b/arch/arm64/kernel/ptrace.c > @@ -1856,12 +1856,12 @@ int syscall_trace_enter(struct pt_regs *regs) > if (flags & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) { > tracehook_report_syscall(regs, PTRACE_SYSCALL_ENTER); > if (!in_syscall(regs) || (flags & _TIF_SYSCALL_EMU)) > - return -1; > + return NO_SYSCALL; > } > > /* Do the secure computing after ptrace; failures should be fast. */ > if (secure_computing() == -1) > - return -1; > + return NO_SYSCALL; > > if (test_thread_flag(TIF_SYSCALL_TRACEPOINT)) > trace_sys_enter(regs, regs->syscallno); > -- > 2.27.0.383.g050319c2ae-goog > -- Kees Cook _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel