[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <CAAH8bW8Zo1U3oMu5Gggp-MyNNZ8_WieQn+GKYiML93O9sJB=Dg@mail.gmail.com>
Date: Wed, 25 Nov 2020 10:14:42 -0800
From: Yury Norov <yury.norov@...il.com>
To: Xiongfeng Wang <wangxiongfeng2@...wei.com>
Cc: bobo.shaobowang@...wei.com,
Catalin Marinas <catalin.marinas@....com>,
Arnd Bergmann <arnd@...db.de>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
"linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
"linux-api@...r.kernel.org" <linux-api@...r.kernel.org>,
Adam Borowski <kilobyte@...band.pl>,
Alexander Graf <agraf@...e.de>,
Alexey Klimov <klimov.linux@...il.com>,
Andreas Schwab <schwab@...e.de>,
Andrew Pinski <pinskia@...il.com>,
Bamvor Zhangjian <bamv2005@...il.com>,
Chris Metcalf <cmetcalf@...lanox.com>,
Christoph Muellner <christoph.muellner@...obroma-systems.com>,
Dave Martin <Dave.Martin@....com>,
"David S . Miller" <davem@...emloft.net>,
Florian Weimer <fweimer@...hat.com>,
Geert Uytterhoeven <geert@...ux-m68k.org>,
Heiko Carstens <heiko.carstens@...ibm.com>,
James Hogan <james.hogan@...tec.com>,
James Morse <james.morse@....com>,
Joseph Myers <joseph@...esourcery.com>,
Lin Yongting <linyongting@...wei.com>,
Manuel Montezelo <manuel.montezelo@...il.com>,
Mark Brown <broonie@...nel.org>,
Martin Schwidefsky <schwidefsky@...ibm.com>,
Maxim Kuvyrkov <maxim.kuvyrkov@...aro.org>,
Nathan_Lynch <Nathan_Lynch@...tor.com>,
Philipp Tomsich <philipp.tomsich@...obroma-systems.com>,
Prasun Kapoor <Prasun.Kapoor@...iumnetworks.com>,
Ramana Radhakrishnan <ramana.gcc@...glemail.com>,
Steve Ellcey <sellcey@...iumnetworks.com>,
Szabolcs Nagy <szabolcs.nagy@....com>
Subject: Re: [Question] About SECCOMP issue for ILP32
On Mon, Aug 31, 2020 at 11:15 AM Yury Norov <yury.norov@...il.com> wrote:
>
> On Mon, Aug 31, 2020 at 5:48 AM Xiongfeng Wang
> <wangxiongfeng2@...wei.com> wrote:
> >
> > Hi Yury,
> >
>
> Hi Xiongfeng,
>
> [restore CC list]
>
> Haven't seen this before. What kernel / glibc / ltp do you use?
>
> > We were testing the ILP32 feature and came accross a problem. Very apperaciate
> > it if you could give us some help !
> >
> > We compile the LTP testsuite with '-mabi=ilp32' and run it on a machine with
> > kernel and glibc applied with ILP32 patches. But we failed on one testcase,
> > prctl04. It print the following error info.
> > 'prctl04.c:199: FAIL: SECCOMP_MODE_STRICT doesn't permit read(2) write(2) and
> > _exit(2)'
> >
> > The testcase is like below, syscall 'prctl' followed by a syscall 'write'.
> > prctl(PR_SET_SECCOMP, SECCOMP_MODE_STRICT);
> > SAFE_WRITE(1, fd, "a", 1);
> >
> > When we execute syscall 'write', we receive a SIGKILL. It's not as expected.
> > We track the kernel and found out it is because we failed the syscall_whitelist
> > check in '__secure_computing_strict'. Because flag 'TIF_32BIT_AARCH64' is set,
> > we falls into the 'in_compat_syscall()' branch. We compare the parameter
> > 'this_syscall' with return value of 'get_compat_model_syscalls()'
> > The syscall number of '__NR_write' for ilp32 application is 64, but it is 4 for
> > 'model_syscalls_32' returned from 'get_compat_model_syscalls()'
> > So '__secure_computing_strict' retuned with 'do_exit(SIGKILL)'. We have a
> > modification like below, but I am not sure if it correct or not.
> >
> > --- a/kernel/seccomp.c
> > +++ b/kernel/seccomp.c
> > @@ -618,7 +618,7 @@ static void __secure_computing_strict(int this_syscall)
> > {
> > const int *syscall_whitelist = mode1_syscalls;
> > #ifdef CONFIG_COMPAT
> > - if (in_compat_syscall())
> > + if (is_a32_compat_task())
> > syscall_whitelist = get_compat_mode1_syscalls();
>
> It calls the arch function from generic code. It may break build for
> other arches.
> This also looks dangerous because it treats ILP32 execution as non-compat.
>
> The right approach would be implementing arch-specific
> get_compat_mode1_syscalls()
> in arch/arm64/include/asm/seccomp.h that returns an appropriate table.
> Refer MIPS
> code for this: arch/mips/include/asm/seccomp.h
>
> Thanks,
> Yury
>
> > #endif
> > do {
> >
> >
> > Thanks,
> > Xiongfeng
> >
The fix is on my repo; versions 5.2 and 4.19 are updated:
https://github.com/norov/linux/commits/ilp32-4.19
https://github.com/norov/linux/commits/ilp32-5.2
Powered by blists - more mailing lists