From: Florian Weimer <fw@deneb.enyo.de>
To: Nicholas Piggin <npiggin@gmail.com>
Cc: Rich Felker <dalias@libc.org>,
Nicholas Piggin via Libc-alpha <libc-alpha@sourceware.org>,
libc-dev@lists.llvm.org, linuxppc-dev@lists.ozlabs.org,
musl@lists.openwall.com
Subject: Re: [musl] Powerpc Linux 'scv' system call ABI proposal take 2
Date: Tue, 21 Apr 2020 11:57:00 +0200 [thread overview]
Message-ID: <87eeshupoz.fsf@mid.deneb.enyo.de> (raw)
In-Reply-To: <20200420211751.GF23945@port70.net> (Szabolcs Nagy's message of "Mon, 20 Apr 2020 23:17:51 +0200")
* Szabolcs Nagy:
> * Nicholas Piggin <npiggin@gmail.com> [2020-04-20 12:08:36 +1000]:
>> Excerpts from Rich Felker's message of April 20, 2020 11:29 am:
>> > Also, allowing patching of executable pages is generally frowned upon
>> > these days because W^X is a desirable hardening property.
>>
>> Right, it would want be write-protected after being patched.
>
> "frowned upon" means that users may have to update
> their security policy setting in pax, selinux, apparmor,
> seccomp bpf filters and who knows what else that may
> monitor and flag W&X mprotect.
>
> libc update can break systems if the new libc does W&X.
It's possible to map over pre-compiled alternative implementations,
though. Basically, we would do the patching and build time and store
the results in the file.
It works best if the variance is concentrated on a few pages, and
there are very few alternatives. For example, having two syscall APIs
and supporting threading and no-threading versions would need four
code versions in total, which is likely excessive.
next prev parent reply other threads:[~2020-04-21 9:57 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-15 21:45 Nicholas Piggin
2020-04-15 22:55 ` Rich Felker
2020-04-16 0:16 ` Nicholas Piggin
2020-04-16 0:48 ` Rich Felker
2020-04-16 2:24 ` Nicholas Piggin
2020-04-16 2:35 ` Rich Felker
2020-04-16 2:53 ` Nicholas Piggin
2020-04-16 3:03 ` Rich Felker
2020-04-16 3:41 ` Nicholas Piggin
2020-04-16 20:18 ` Florian Weimer
2020-04-16 9:58 ` Szabolcs Nagy
2020-04-20 0:27 ` Nicholas Piggin
2020-04-20 1:29 ` Rich Felker
2020-04-20 2:08 ` Nicholas Piggin
2020-04-20 21:17 ` Szabolcs Nagy
2020-04-21 9:57 ` Florian Weimer [this message]
2020-04-16 15:21 ` Jeffrey Walton
2020-04-16 15:40 ` Rich Felker
2020-04-16 4:48 ` Florian Weimer
2020-04-16 15:35 ` Rich Felker
2020-04-16 16:42 ` Florian Weimer
2020-04-16 16:52 ` Rich Felker
2020-04-16 18:12 ` Florian Weimer
2020-04-16 23:02 ` Segher Boessenkool
2020-04-17 0:34 ` Rich Felker
2020-04-17 1:48 ` Segher Boessenkool
2020-04-17 8:34 ` Florian Weimer
2020-04-16 14:16 ` Adhemerval Zanella
2020-04-16 15:37 ` Rich Felker
2020-04-16 17:50 ` Adhemerval Zanella
2020-04-16 17:59 ` Rich Felker
2020-04-16 18:18 ` Adhemerval Zanella
2020-04-16 18:31 ` Rich Felker
2020-04-16 18:44 ` Rich Felker
2020-04-16 18:52 ` Adhemerval Zanella
2020-04-20 0:46 ` Nicholas Piggin
2020-04-20 1:10 ` Nicholas Piggin
2020-04-20 1:34 ` Rich Felker
2020-04-20 2:32 ` Nicholas Piggin
2020-04-20 4:09 ` Rich Felker
2020-04-20 4:31 ` Nicholas Piggin
2020-04-20 17:27 ` Rich Felker
2020-04-22 6:18 ` Nicholas Piggin
2020-04-22 6:29 ` Nicholas Piggin
2020-04-23 2:36 ` Rich Felker
2020-04-23 12:13 ` Adhemerval Zanella
2020-04-23 16:18 ` Rich Felker
2020-04-23 16:35 ` Adhemerval Zanella
2020-04-23 16:43 ` Rich Felker
2020-04-23 17:15 ` Adhemerval Zanella
2020-04-23 17:42 ` Rich Felker
2020-04-25 3:40 ` Nicholas Piggin
2020-04-25 4:52 ` Rich Felker
2020-04-25 3:30 ` Nicholas Piggin
2020-04-21 12:28 ` David Laight
2020-04-21 14:39 ` Rich Felker
2020-04-21 15:00 ` Adhemerval Zanella
2020-04-21 15:31 ` David Laight
2020-04-22 6:54 ` [musl] " Nicholas Piggin
2020-04-22 7:15 ` Florian Weimer
2020-04-22 7:31 ` Nicholas Piggin
2020-04-22 8:11 ` Florian Weimer
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