From: Michael Ellerman <mpe@ellerman.id.au>
To: Kees Cook <keescook@chromium.org>, linux-kernel@vger.kernel.org
Cc: Kees Cook <keescook@chromium.org>,
Thadeu Lima de Souza Cascardo <cascardo@canonical.com>,
Max Filippov <jcmvbkbc@gmail.com>,
Christian Brauner <christian@brauner.io>,
Andy Lutomirski <luto@amacapital.net>,
Will Drewry <wad@chromium.org>,
linux-kselftest@vger.kernel.org, linux-mips@vger.kernel.org,
linux-xtensa@linux-xtensa.org,
linux-arm-kernel@lists.infradead.org,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 13/15] selftests/seccomp: powerpc: Set syscall return during ptrace syscall exit
Date: Mon, 14 Sep 2020 15:47:13 +1000 [thread overview]
Message-ID: <87zh5sq59a.fsf@mpe.ellerman.id.au> (raw)
In-Reply-To: <20200912110820.597135-14-keescook@chromium.org>
Kees Cook <keescook@chromium.org> writes:
> Some archs (like ppc) only support changing the return code during
> syscall exit when ptrace is used. As the syscall number might not
> be available anymore during syscall exit, it needs to be saved
> during syscall enter. Adjust the ptrace tests to do this.
I'm not that across all the fixture stuff, but if I'm reading it right
you're now calling change_syscall() on both entry and exit for all
arches.
That should work, but it no longer tests changing the return code on
entry on the arches that support it, which seems like a backward step?
cheers
> Reported-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
> Suggested-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
> Link: https://lore.kernel.org/linux-kselftest/20200911181012.171027-1-cascardo@canonical.com/
> Fixes: 58d0a862f573 ("seccomp: add tests for ptrace hole")
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
> tools/testing/selftests/seccomp/seccomp_bpf.c | 34 +++++++++++--------
> 1 file changed, 20 insertions(+), 14 deletions(-)
>
> diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c
> index bbab2420d708..26c712c6a575 100644
> --- a/tools/testing/selftests/seccomp/seccomp_bpf.c
> +++ b/tools/testing/selftests/seccomp/seccomp_bpf.c
> @@ -1949,12 +1949,19 @@ void tracer_seccomp(struct __test_metadata *_metadata, pid_t tracee,
>
> }
>
> +FIXTURE(TRACE_syscall) {
> + struct sock_fprog prog;
> + pid_t tracer, mytid, mypid, parent;
> + long syscall_nr;
> +};
> +
> void tracer_ptrace(struct __test_metadata *_metadata, pid_t tracee,
> int status, void *args)
> {
> - int ret, nr;
> + int ret;
> unsigned long msg;
> static bool entry;
> + FIXTURE_DATA(TRACE_syscall) *self = args;
>
> /*
> * The traditional way to tell PTRACE_SYSCALL entry/exit
> @@ -1968,24 +1975,23 @@ void tracer_ptrace(struct __test_metadata *_metadata, pid_t tracee,
> EXPECT_EQ(entry ? PTRACE_EVENTMSG_SYSCALL_ENTRY
> : PTRACE_EVENTMSG_SYSCALL_EXIT, msg);
>
> - if (!entry)
> - return;
> -
> - nr = get_syscall(_metadata, tracee);
> + /*
> + * Some architectures only support setting return values during
> + * syscall exit under ptrace, and on exit the syscall number may
> + * no longer be available. Therefore, save it here, and call
> + * "change syscall and set return values" on both entry and exit.
> + */
> + if (entry)
> + self->syscall_nr = get_syscall(_metadata, tracee);
>
> - if (nr == __NR_getpid)
> + if (self->syscall_nr == __NR_getpid)
> change_syscall(_metadata, tracee, __NR_getppid, 0);
> - if (nr == __NR_gettid)
> + if (self->syscall_nr == __NR_gettid)
> change_syscall(_metadata, tracee, -1, 45000);
> - if (nr == __NR_openat)
> + if (self->syscall_nr == __NR_openat)
> change_syscall(_metadata, tracee, -1, -ESRCH);
> }
>
> -FIXTURE(TRACE_syscall) {
> - struct sock_fprog prog;
> - pid_t tracer, mytid, mypid, parent;
> -};
> -
> FIXTURE_VARIANT(TRACE_syscall) {
> /*
> * All of the SECCOMP_RET_TRACE behaviors can be tested with either
> @@ -2044,7 +2050,7 @@ FIXTURE_SETUP(TRACE_syscall)
> self->tracer = setup_trace_fixture(_metadata,
> variant->use_ptrace ? tracer_ptrace
> : tracer_seccomp,
> - NULL, variant->use_ptrace);
> + self, variant->use_ptrace);
>
> ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
> ASSERT_EQ(0, ret);
> --
> 2.25.1
next prev parent reply other threads:[~2020-09-14 5:47 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-12 11:08 [PATCH 00/15] selftests/seccomp: Refactor change_syscall() Kees Cook
2020-09-12 11:08 ` [PATCH 01/15] selftests/seccomp: Refactor arch register macros to avoid xtensa special case Kees Cook
2020-09-15 15:51 ` Christian Brauner
2020-09-12 11:08 ` [PATCH 02/15] selftests/seccomp: Provide generic syscall setting macro Kees Cook
2020-09-15 15:53 ` Christian Brauner
2020-09-12 11:08 ` [PATCH 03/15] selftests/seccomp: mips: Define SYSCALL_NUM_SET macro Kees Cook
2020-09-15 15:55 ` Christian Brauner
2020-09-18 22:00 ` Kees Cook
2020-09-12 11:08 ` [PATCH 04/15] selftests/seccomp: arm: " Kees Cook
2020-09-15 15:56 ` Christian Brauner
2020-09-12 11:08 ` [PATCH 05/15] selftests/seccomp: arm64: " Kees Cook
2020-09-15 15:58 ` Christian Brauner
2020-09-12 11:08 ` [PATCH 06/15] selftests/seccomp: mips: Remove O32-specific macro Kees Cook
2020-09-15 16:00 ` Christian Brauner
2020-09-12 11:08 ` [PATCH 07/15] selftests/seccomp: Remove syscall setting #ifdefs Kees Cook
2020-09-15 16:01 ` Christian Brauner
2020-09-12 11:08 ` [PATCH 08/15] selftests/seccomp: Convert HAVE_GETREG into ARCH_GETREG/ARCH_SETREG Kees Cook
2020-09-15 16:03 ` Christian Brauner
2020-09-12 11:08 ` [PATCH 09/15] selftests/seccomp: Convert REGSET calls " Kees Cook
2020-09-15 16:05 ` Christian Brauner
2020-09-12 11:08 ` [PATCH 10/15] selftests/seccomp: Avoid redundant register flushes Kees Cook
2020-09-15 16:08 ` Christian Brauner
2020-09-12 11:08 ` [PATCH 11/15] selftests/seccomp: Remove SYSCALL_NUM_RET_SHARE_REG in favor of SYSCALL_RET_SET Kees Cook
2020-09-15 16:11 ` Christian Brauner
2020-09-12 11:08 ` [PATCH 12/15] selftests/seccomp: powerpc: Fix seccomp return value testing Kees Cook
2020-09-14 3:38 ` Michael Ellerman
2020-09-12 11:08 ` [PATCH 13/15] selftests/seccomp: powerpc: Set syscall return during ptrace syscall exit Kees Cook
2020-09-14 5:47 ` Michael Ellerman [this message]
2020-09-14 20:20 ` Kees Cook
2020-09-12 11:08 ` [PATCH 14/15] selftests/clone3: Avoid OS-defined clone_args Kees Cook
2020-09-15 16:25 ` Christian Brauner
2020-09-18 22:00 ` Kees Cook
2020-09-12 11:08 ` [PATCH 15/15] selftests/seccomp: Use __NR_mknodat instead of __NR_mknod Kees Cook
2020-09-15 16:16 ` Christian Brauner
2020-09-14 12:15 ` [PATCH 00/15] selftests/seccomp: Refactor change_syscall() Michael Ellerman
2020-09-14 20:32 ` Kees Cook
2020-09-15 11:12 ` Max Filippov
2020-09-15 12:52 ` Michael Ellerman
2020-09-15 8:45 ` Max Filippov
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