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From: Alexander Monakov <amonakov@ispras.ru>
To: musl@lists.openwall.com
Cc: Andrew Rogers <andrew.rogerstech@gmail.com>
Subject: Re: [musl] Potential DL_NOMMU_SUPPORT bug.
Date: Sun, 24 Jan 2021 21:48:11 +0300 (MSK)	[thread overview]
Message-ID: <alpine.LNX.2.20.13.2101242140070.31613@monopod.intra.ispras.ru> (raw)
In-Reply-To: <20210124181036.GS23432@brightrain.aerifal.cx>

> > sdcard [pseudo-]partition is usually mounted noexec, so mmap with PROT_EXEC
> > should fail.
> 
> Uhg, that makes no sense. Does it enforce that even for MAP_PRIVATE,
> which should semantically be equivalent to just making anon memory
> with the requested permissions and copying the file contents into it??

I think it makes sense: isn't the entire point of 'noexec' that a user
who has write access only to noexec filesystems will not be able to run
arbitrary binary code (assuming the already-present binaries are not
cooperative, unlike musl ld.so with the above patch would be)? Enforcing
noexec for MAP_PRIVATE ensures the users can not trivially side-step
noexec by invoking ld.so (without extra checks on ld.so side).

Alexander

  reply	other threads:[~2021-01-24 18:48 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-23  6:47 Andrew Rogers
2021-01-24 15:40 ` Rich Felker
2021-01-24 15:58   ` Alexander Monakov
2021-01-24 18:10     ` Rich Felker
2021-01-24 18:48       ` Alexander Monakov [this message]
2021-01-24 18:55         ` Rich Felker
2021-01-30 17:44           ` Andrew Rogers
2021-01-30 19:01             ` Rich Felker

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