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From: Florian Weimer <fw@deneb.enyo.de>
To: Mark Wielaard <mark@klomp.org>
Cc: libc-alpha@sourceware.org
Subject: Re: [PATCH 3/4] tst-pidfd.c: Test is UNSUPPORTED without
 PTRACE_MODE_ATTACH_REALCREDS
References: <20220626205915.33201-1-mark@klomp.org>
 <20220626205915.33201-4-mark@klomp.org>
Date: Sun, 26 Jun 2022 23:20:26 +0200
In-Reply-To: <20220626205915.33201-4-mark@klomp.org> (Mark Wielaard's message
 of "Sun, 26 Jun 2022 22:59:14 +0200")
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* Mark Wielaard:

> pidfd_getfd will fail with errno EPERM if the calling process did not
> have PTRACE_MODE_ATTACH_REALCREDS permissions. Use FAIL_UNSUPPORTED
> in that case.
> ---
>  sysdeps/unix/sysv/linux/tst-pidfd.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/sysdeps/unix/sysv/linux/tst-pidfd.c b/sysdeps/unix/sysv/linux/tst-pidfd.c
> index d93b6faa6f..28349b2f91 100644
> --- a/sysdeps/unix/sysv/linux/tst-pidfd.c
> +++ b/sysdeps/unix/sysv/linux/tst-pidfd.c
> @@ -95,8 +95,10 @@ do_test (void)
>         kernel has pidfd support that we can test.  */
>      int r = pidfd_getfd (0, 0, 1);
>      TEST_VERIFY_EXIT (r == -1);
> -    if (errno == ENOSYS)
> -      FAIL_UNSUPPORTED ("kernel does not support pidfd_getfd, skipping test");
> +    if (errno == ENOSYS || errno == EPERM)
> +      FAIL_UNSUPPORTED ("kernel does not support pidfd_getfd,"
> +			" or we don't have PTRACE_MODE_ATTACH_REALCREDS"
> +			" permissions, skipping test");
>    }

This also hints towards a broken seccomp filter.