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Date:      Mon, 15 May 2017 22:52:36 +0300
From:      Konstantin Belousov <kostikbel@gmail.com>
To:        Alexey Dokuchaev <danfe@FreeBSD.org>
Cc:        Nikolai Lifanov <lifanov@FreeBSD.org>, svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org, Ian Lepore <ian@freebsd.org>
Subject:   Re: svn commit: r318313 - head/libexec/rtld-elf
Message-ID:  <20170515195236.GK1622@kib.kiev.ua>
In-Reply-To: <20170515194223.GE28684@FreeBSD.org>
References:  <201705151848.v4FImwMW070221@repo.freebsd.org> <20170515185236.GB1637@FreeBSD.org> <20170515190030.GG1622@kib.kiev.ua> <1494875335.59865.118.camel@freebsd.org> <20170515192529.GH1622@kib.kiev.ua> <20170515193609.GC28684@FreeBSD.org> <c9f4d964-e530-c767-1031-de825bcbe38d@FreeBSD.org> <20170515194049.GJ1622@kib.kiev.ua> <20170515194223.GE28684@FreeBSD.org>

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On Mon, May 15, 2017 at 07:42:23PM +0000, Alexey Dokuchaev wrote:
> On Mon, May 15, 2017 at 10:40:49PM +0300, Konstantin Belousov wrote:
> > On Mon, May 15, 2017 at 03:37:42PM -0400, Nikolai Lifanov wrote:
> > > On 05/15/2017 15:36, Alexey Dokuchaev wrote:
> > > > ...
> > > > Would this now allow executing binaries (with or without +x bit) from
> > > > filesystems mounted with -o noexec?
> > > 
> > > No:
> > > 
> > > # zfs create -o mountpoint=/mnt -o exec=off tank/TEST
> > > # cp /bin/sh /mnt/
> > > # /mnt/sh
> > > /mnt/sh: Permission denied.
> > > # /libexec/ld-elf.so.1 /mnt/sh
> > > /mnt/sh: mmap of data failed: Permission denied
> > 
> > This is due to
> > r313967 | kib | 2017-02-19 22:51:04 +0200 (Sun, 19 Feb 2017) | 24 lines
> > Apply noexec mount option for mmap(PROT_EXEC).
> 
> Nice, good to know that.

[Replying to random mail in thread]

I tried this on an up to date latest Fedora installation:
[kostik@sandy ~]$ cp /bin/ls /tmp
[kostik@sandy ~]$ chmod a-x /tmp/ls
[kostik@sandy ~]$ /lib64/ld-linux-x86-64.so.2  /tmp/ls
Dropbox  intel  tmp  work

I am not sure about one detail, the /tmp/ls file has some security context
on it, but I do not believe that it may affect the outcome of the experiment.
Please correct me if I am wrong.



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