From: jma14 <jma14@rice.edu>
To: Florian Weimer <fweimer@redhat.com>,
Adhemerval Zanella <adhemerval.zanella@linaro.org>
Cc: John Mellor-Crummey <johnmc@rice.edu>, libc-alpha@sourceware.org
Subject: Re: [PATCH v7 00/16] Multiple rtld-audit fixes
Date: Sun, 26 Dec 2021 23:08:38 -0600 [thread overview]
Message-ID: <20211226230838.Horde.rgXNVMCGczjIF-p2OppMvp9@webmail.rice.edu> (raw)
On December 24, 2021 5:49:23 AM CST, Florian Weimer via Libc-alpha
<libc-alpha@sourceware.org> wrote:
> * Adhemerval Zanella:
>
>> There is also some point brough by John Melloc-Crummey documents that
>> I don't have a straighforward answer so I haven't added on this
>> patchset:
>>
>> 1 la_activity(LA_ACT_ADD) is never called for auditor namespaces,
>> even though la_objopen and la_activity(LA_ACT_CONSISTENT) are.
>>
>> There is no easy solution for this: we need at least to load the
>> *first* auditor to actually issue the la_activity(LA_ACT_ADD). It
>> means that it would *only* work for subsequent audit modules, and
>> adding this specific semantic is confusing and does not really
>> improve things (it only helps when multiple audit modules are used).
>
> I suspect we shouldn't call auditors for audit namespaces. Or perhaps
> only for later audit namespaces, but not earlier ones.
For our purposes in HPCToolkit, we would prefer the latter of these
two options. This would allow us to easily analyze the performance of
other auditors such as Spindle.
>> 3. For non-PIE executables the base address listed in link_map->l_addr
>> for the main application binary is 0, even though dladdr is able to
>> recover the correct offset. La_objopen is affected by this.
>
> Agreed.
I am (personally) still concerned about this issue. Thanks to your
explanation I am less concerned about the getauxval workaround causing
subtle bugs, but this method is still not portable (to non-Linux) and
I find the documentation surrounding l_addr and dladdr insufficient.
Same with l_name, as we discussed previously.
This issue does not need to be addressed in this patch series, but I
would feel more comfortable with a clear resolution plan since I
believe that this issue significantly degrades the usability of the
rtld-audit interface.
-Jonathon
next reply other threads:[~2021-12-27 5:08 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-27 5:08 jma14 [this message]
-- strict thread matches above, loose matches on Subject: below --
2021-12-22 13:26 Adhemerval Zanella
2021-12-24 11:49 ` Florian Weimer
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