From: AKASHI Takahiro <takahiro.akashi@linaro.org> To: Will Deacon <will.deacon@arm.com> Cc: Kees Cook <keescook@chromium.org>, Catalin Marinas <Catalin.Marinas@arm.com>, Deepak Saxena <dsaxena@linaro.org>, "arndb@arndb.de" <arndb@arndb.de>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>, "linaro-kernel@lists.linaro.org" <linaro-kernel@lists.linaro.org>, LKML <linux-kernel@vger.kernel.org> Subject: Re: [PATCH v6 2/6] arm64: ptrace: allow tracer to skip a system call Date: Tue, 02 Sep 2014 16:58:38 +0900 [thread overview] Message-ID: <540578AE.8090000@linaro.org> (raw) In-Reply-To: <20140901113755.GA24594@arm.com> On 09/01/2014 08:37 PM, Will Deacon wrote: > On Wed, Aug 27, 2014 at 06:55:46AM +0100, AKASHI Takahiro wrote: >> On 08/27/2014 02:51 AM, Will Deacon wrote: >>> On Fri, Aug 22, 2014 at 01:35:17AM +0100, AKASHI Takahiro wrote: >>>> Oops, you're absolutely right. I didn't think of this case. >>>> syscall_trace_enter() should not return a syscallno directly, but always >>>> return -1 if syscallno < 0. (except when secure_computing() returns with -1) >>>> This also implies that tracehook_report_syscall() should also have a return value. >>>> >>>> Will, is this fine with you? >>> >>> Well, the first thing that jumps out at me is why this is being done >>> completely differently for arm64 and arm. I thought adding the new ptrace >>> requests would reconcile the differences? >> >> I'm not sure what portion of my code you mentioned as "completely different", but >> >> 1) >> setting x0 to -ENOSYS is necessary because, otherwise, user-issued syscall(-1) will >> return a bogus value when audit tracing is on. >> >> Please note that, on arm, >> not traced traced >> ------ ------ >> syscall(-1) aborted OOPs(BUG_ON) >> syscall(-3000) aborted aborted >> syscall(1000) ENOSYS ENOSYS >> >> So, anyhow, its a bit difficult and meaningless to mimic these invalid cases. > > I'm not suggesting we make ourselves bug-compatible with ARM. Instead, I'd > rather see a series of patches getting the ARM code working correctly, > before we go off doing something different for arm64. I see. >> 2) >> branching a new label, syscall_trace_return_skip (see entry.S), after syscall_trace_enter() >> is necessary in order to avoid OOPS in audit_syscall_enter() as we discussed. >> >> Did I make it clear? > > Sure. So let's fix ARM, then look at the arm64 port after that. I really > want to avoid divergence in this area. Okey, I will start with fixing the issue on arm. -Takahiro AKASHI > Will >
WARNING: multiple messages have this Message-ID (diff)
From: takahiro.akashi@linaro.org (AKASHI Takahiro) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v6 2/6] arm64: ptrace: allow tracer to skip a system call Date: Tue, 02 Sep 2014 16:58:38 +0900 [thread overview] Message-ID: <540578AE.8090000@linaro.org> (raw) In-Reply-To: <20140901113755.GA24594@arm.com> On 09/01/2014 08:37 PM, Will Deacon wrote: > On Wed, Aug 27, 2014 at 06:55:46AM +0100, AKASHI Takahiro wrote: >> On 08/27/2014 02:51 AM, Will Deacon wrote: >>> On Fri, Aug 22, 2014 at 01:35:17AM +0100, AKASHI Takahiro wrote: >>>> Oops, you're absolutely right. I didn't think of this case. >>>> syscall_trace_enter() should not return a syscallno directly, but always >>>> return -1 if syscallno < 0. (except when secure_computing() returns with -1) >>>> This also implies that tracehook_report_syscall() should also have a return value. >>>> >>>> Will, is this fine with you? >>> >>> Well, the first thing that jumps out at me is why this is being done >>> completely differently for arm64 and arm. I thought adding the new ptrace >>> requests would reconcile the differences? >> >> I'm not sure what portion of my code you mentioned as "completely different", but >> >> 1) >> setting x0 to -ENOSYS is necessary because, otherwise, user-issued syscall(-1) will >> return a bogus value when audit tracing is on. >> >> Please note that, on arm, >> not traced traced >> ------ ------ >> syscall(-1) aborted OOPs(BUG_ON) >> syscall(-3000) aborted aborted >> syscall(1000) ENOSYS ENOSYS >> >> So, anyhow, its a bit difficult and meaningless to mimic these invalid cases. > > I'm not suggesting we make ourselves bug-compatible with ARM. Instead, I'd > rather see a series of patches getting the ARM code working correctly, > before we go off doing something different for arm64. I see. >> 2) >> branching a new label, syscall_trace_return_skip (see entry.S), after syscall_trace_enter() >> is necessary in order to avoid OOPS in audit_syscall_enter() as we discussed. >> >> Did I make it clear? > > Sure. So let's fix ARM, then look at the arm64 port after that. I really > want to avoid divergence in this area. Okey, I will start with fixing the issue on arm. -Takahiro AKASHI > Will >
next prev parent reply other threads:[~2014-09-02 7:58 UTC|newest] Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top 2014-08-21 8:56 [PATCH v6 0/6] arm64: add seccomp support AKASHI Takahiro 2014-08-21 8:56 ` AKASHI Takahiro 2014-08-21 8:56 ` [PATCH v6 1/6] arm64: ptrace: add PTRACE_SET_SYSCALL AKASHI Takahiro 2014-08-21 8:56 ` AKASHI Takahiro 2014-08-21 16:47 ` Kees Cook 2014-08-21 16:47 ` Kees Cook 2014-08-22 0:19 ` AKASHI Takahiro 2014-08-22 0:19 ` AKASHI Takahiro 2014-08-26 17:46 ` Will Deacon 2014-08-26 17:46 ` Will Deacon 2014-08-27 5:32 ` AKASHI Takahiro 2014-08-27 5:32 ` AKASHI Takahiro 2014-09-03 18:34 ` Kees Cook 2014-09-03 18:34 ` Kees Cook 2014-08-21 8:56 ` [PATCH v6 2/6] arm64: ptrace: allow tracer to skip a system call AKASHI Takahiro 2014-08-21 8:56 ` AKASHI Takahiro 2014-08-21 17:08 ` Kees Cook 2014-08-21 17:08 ` Kees Cook 2014-08-22 0:35 ` AKASHI Takahiro 2014-08-22 0:35 ` AKASHI Takahiro 2014-08-26 17:51 ` Will Deacon 2014-08-26 17:51 ` Will Deacon 2014-08-27 5:55 ` AKASHI Takahiro 2014-08-27 5:55 ` AKASHI Takahiro 2014-09-01 11:37 ` Will Deacon 2014-09-01 11:37 ` Will Deacon 2014-09-02 7:58 ` AKASHI Takahiro [this message] 2014-09-02 7:58 ` AKASHI Takahiro 2014-09-01 11:47 ` Russell King - ARM Linux 2014-09-01 11:47 ` Russell King - ARM Linux 2014-09-02 8:47 ` AKASHI Takahiro 2014-09-02 8:47 ` AKASHI Takahiro 2014-09-02 9:16 ` Russell King - ARM Linux 2014-09-02 9:16 ` Russell King - ARM Linux 2014-09-02 9:31 ` Russell King - ARM Linux 2014-09-02 9:31 ` Russell King - ARM Linux 2014-09-05 10:08 ` AKASHI Takahiro 2014-09-05 10:08 ` AKASHI Takahiro 2014-10-01 11:08 ` AKASHI Takahiro 2014-10-01 11:08 ` AKASHI Takahiro 2014-10-03 15:23 ` Will Deacon 2014-10-03 15:23 ` Will Deacon 2014-10-06 8:04 ` AKASHI Takahiro 2014-10-06 8:04 ` AKASHI Takahiro 2014-08-21 8:56 ` [PATCH v6 3/6] asm-generic: add generic seccomp.h for secure computing mode 1 AKASHI Takahiro 2014-08-21 8:56 ` AKASHI Takahiro 2014-08-21 17:51 ` Kees Cook 2014-08-21 17:51 ` Kees Cook 2014-08-22 0:38 ` AKASHI Takahiro 2014-08-22 0:38 ` AKASHI Takahiro 2014-08-21 8:56 ` [PATCH v6 4/6] arm64: add seccomp syscall for compat task AKASHI Takahiro 2014-08-21 8:56 ` AKASHI Takahiro 2014-08-21 17:52 ` Kees Cook 2014-08-21 17:52 ` Kees Cook 2014-08-22 0:39 ` AKASHI Takahiro 2014-08-22 0:39 ` AKASHI Takahiro 2014-08-26 17:53 ` Will Deacon 2014-08-26 17:53 ` Will Deacon 2014-08-27 5:57 ` AKASHI Takahiro 2014-08-27 5:57 ` AKASHI Takahiro 2014-08-21 8:56 ` [PATCH v6 5/6] arm64: add SIGSYS siginfo " AKASHI Takahiro 2014-08-21 8:56 ` AKASHI Takahiro 2014-08-21 17:54 ` Kees Cook 2014-08-21 17:54 ` Kees Cook 2014-08-22 0:44 ` AKASHI Takahiro 2014-08-22 0:44 ` AKASHI Takahiro 2014-08-26 17:55 ` Will Deacon 2014-08-26 17:55 ` Will Deacon 2014-08-27 5:58 ` AKASHI Takahiro 2014-08-27 5:58 ` AKASHI Takahiro 2014-08-21 8:56 ` [PATCH v6 6/6] arm64: add seccomp support AKASHI Takahiro 2014-08-21 8:56 ` AKASHI Takahiro
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