conf/164048: /etc/rc.d/hostid is not symlink aware

Thu Jan 12 21:00:30 UTC 2012

The following reply was made to PR conf/164048; it has been noted by GNATS.

From: Matthew Story <matthewstory at gmail.com>
To: Dirk-Willem van Gulik <dirkx at webweaving.org>
Cc: freebsd-bugs at freebsd.org, freebsd-gnats-submit at freebsd.org
Subject: Re: conf/164048: /etc/rc.d/hostid is not symlink aware
Date: Thu, 12 Jan 2012 15:51:48 -0500

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 On Thu, Jan 12, 2012 at 2:47 PM, Dirk-Willem van Gulik <dirkx at webweaving.org
 > wrote:

 >
 > On 12 jan. 2012, at 17:48, Matthew Story wrote:
 >
 > > On Thu, Jan 12, 2012 at 3:15 AM, Dirk-Willem van Gulik <
 > dirkx at webweaving.org> wrote:
 >
 [...snip]

 > Totally understood - but wanted to stay close to the behavior of
 > dhclient-script as I understand it.  And this happens to also make the
 > behavior of /etc/rc.d/sshd on first run the same. Keep in mind that one can
 > always set the rc variable.
 >

 it makes sense to test for existence (and not readability) for rc.d/sshd,
 as it goes on to create files if they do not exist:

     if [ -f /etc/ssh/ssh_host_key ]; then
         echo "You already have an RSA host key" \
             "in /etc/ssh/ssh_host_key"
         echo "Skipping protocol version 1 RSA Key Generation"
     else
         /usr/bin/ssh-keygen -t rsa1 -b 1024 \
             -f /etc/ssh/ssh_host_key -N ''
     fi

 in the existing implementation of rc.d/hostid, it does not create the file
 on ``start'' if it does not exist, so detection of readability is more
 correct (although in the typical use-case e.g. running as root, existence
 and readability are ostensibly synonymous).

 > [...snip]
 >
 > Agreed - as _set is better.
 > [...snip]
 >

 So the question is not about respecting symlinks, but wether or not a
 ``host_id_file'' should be created if one does not exist, for the ``start''
 command.  I'm not sure if this behavior is desirable, considering that the
 de facto behavior is to respect hardware derived ``smbios.system.uuid'',
 and writing that value to disk would potentially require an additional
 reset on hardware change.

 As you can easily generate a ``host_id_file'' if one does not exist by
 invoking the ``reset'' command, and the sysctl is set at start properly,
 either from ``host_id_file'', hardware or via the ``uuidgen'' program, this
 seems superfluous to me ... but I defer to the maintainer.

 -- 
 regards,
 matt

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 On Thu, Jan 12, 2012 at 2:47 PM, Dirk-Willem van Gulik <span dir=3D"ltr">&l=
 t;<a href=3D"mailto:dirkx at webweaving.org">dirkx at webweaving.org</a>&gt;</spa=
 n> wrote:<br><div class=3D"gmail_quote"><blockquote class=3D"gmail_quote" s=
 tyle=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
 <div class=3D"im"><br>
 On 12 jan. 2012, at 17:48, Matthew Story wrote:<br>
 <br>
 &gt; On Thu, Jan 12, 2012 at 3:15 AM, Dirk-Willem van Gulik &lt;<a href=3D"=
 mailto:dirkx at webweaving.org">dirkx at webweaving.org</a>&gt; wrote:<br></div><=
 /blockquote><div>[...snip]=A0</div><blockquote class=3D"gmail_quote" style=
 =3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
 <div class=3D"im"></div>Totally understood - but wanted to stay close to th=
 e behavior of dhclient-script as I understand it. =A0And this happens to al=
 so make the behavior of /etc/rc.d/sshd on first run the same. Keep in mind =
 that one can always set the rc variable.<br>
 </blockquote><div><br></div><div>it makes sense to test for existence (and =
 not readability) for rc.d/sshd, as it goes on to create files if they do no=
 t exist:</div><div><br></div><div><div>=A0=A0 =A0if [ -f /etc/ssh/ssh_host_=
 key ]; then</div>
 <div>=A0=A0 =A0 =A0 =A0echo &quot;You already have an RSA host key&quot; \<=
 /div><div>=A0=A0 =A0 =A0 =A0 =A0 =A0&quot;in /etc/ssh/ssh_host_key&quot;</d=
 iv><div>=A0=A0 =A0 =A0 =A0echo &quot;Skipping protocol version 1 RSA Key Ge=
 neration&quot;</div><div>=A0=A0 =A0else</div>
 <div>=A0=A0 =A0 =A0 =A0/usr/bin/ssh-keygen -t rsa1 -b 1024 \</div><div>=A0=
 =A0 =A0 =A0 =A0 =A0 =A0-f /etc/ssh/ssh_host_key -N &#39;&#39;</div><div>=A0=
 =A0 =A0fi =A0</div></div><div><br></div><div>in the existing implementation=
  of rc.d/hostid, it does not create the file on ``start&#39;&#39; if it doe=
 s not exist, so detection of readability is more correct (although in the t=
 ypical use-case e.g. running as root, existence and readability are ostensi=
 bly synonymous).</div>
 <div>=A0</div><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;=
 border-left:1px #ccc solid;padding-left:1ex">[...snip]<br>
 <div class=3D"im"><br>
 </div>Agreed - as _set is better.<br>
 <div class=3D"im">[...snip]</div></blockquote></div><div><br></div>So the q=
 uestion is not about respecting symlinks, but wether or not a ``host_id_fil=
 e&#39;&#39; should be created if one does not exist, for the ``start&#39;&#=
 39; command. =A0I&#39;m not sure if this behavior is desirable, considering=
  that the de facto behavior is to respect hardware derived ``smbios.system.=
 uuid&#39;&#39;, and writing that value to disk would potentially require an=
  additional reset on hardware change.<div>
 <br></div><div>As you can easily generate a ``host_id_file&#39;&#39; if one=
  does not exist by invoking the ``reset&#39;&#39; command, and the sysctl i=
 s set at start properly, either from ``host_id_file&#39;&#39;, hardware or =
 via the ``uuidgen&#39;&#39; program, this seems superfluous to me ... but I=
  defer to the maintainer.<div>
 <div><br></div>-- <br>regards,<br>matt<br>
 </div></div>

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