Re: f26 chroot PATH doesn't include /bin

[Tony Nelson]

On 17-08-31 14:43:10, Rick Stevens wrote:

On 08/31/2017 11:14 AM, Tony Nelson wrote:
> On 17-08-31 12:41:09, Mike Wright wrote:
>
>> How about using "env":  env PATH="new_path" chroot /some_dir
>>
>> Wouldn't this preempt the passed PATH, profile, bashrc, and the dot
>> files?  If so, chroot could be defined as an alias to "env ...  
chroot"

>> and thereby eliminate the problem.
>
> Seems to work.  Note that this only changes the passed path; any
> pathmunge()'ing in the chroot's startup scripts still happens.  I've
> already fixed the problem inside the chroot, but I'll set this up if
> I find another problematic chroot.  It should be OK to look at
> /usr/bin twice if /bin -> /usr/bin and the command doesn't exist.

If the pathmunging is done in a "//etc/..." script
or in a "~/.whatever", absolutely as that is done after the chroot
spawns the shell in the chrooted environment. If you're saying it
happens before the chroot, then I don't know how that'd occur.


No, I didn't say that.  I said "I've already fixed the problem inside
the chroot".



I think the issue you've been having is that your chroot environment
doesn't have the merged /bin and /usr/bin. It has separate /bin and
/usr/bin directories. After the merge of /bin and /usr/bin was
established, I believe bash's built-in default PATH was modified to
assume this symlink was done. That's why the new bash doesn't have a
separate "/bin" in its default path.


bash's default path is not being used; if it were, it would be the
CentOS5 bash.  PATH is set in the chroot environment by chroot itself,
which is how the outer PATH or the env PATH get into it.  The f20 chroot
works because it postdates the /bin -> /usr/bin merge and doesn't need
/bin in PATH.  CentOS5 has separate /bin and /usr/bin, and needs /bin in
PATH.  That can be passed in, as with env, or done in the chroot by
pathmunge'ing in a bash startup script in /etc/profile.d (both
/etc/profile and /etc/bashrc source that directory).

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Re: f26 chroot PATH doesn't include /bin

[Tony Nelson]

On 17-08-31 11:34:21, Kevin Cummings wrote:

On 08/30/17 15:16, Tony Nelson wrote:
> I have an old CentOS5 that I chroot into.  On my old f20 box, PATH
> included /bin, but now on f26 it does not.  I don't understand how

For a while now, /bin should be a link to /usr/bin.  is /usr/bin in  
the

PATH?


CentOS5.

It is still a mystery how it worked on f20, as it postdates the /bin
-> /usr/bin merge and its PATH does not contain /bin.

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Re: f26 chroot PATH doesn't include /bin

[Rick Stevens]

On 08/31/2017 11:14 AM, Tony Nelson wrote:
> On 17-08-31 12:41:09, Mike Wright wrote:
> 
>> How about using "env":  env PATH="new_path" chroot /some_dir
>>
>> Wouldn't this preempt the passed PATH, profile, bashrc, and the dot
>> files?  If so, chroot could be defined as an alias to "env ... chroot"
>> and thereby eliminate the problem.
> 
> Seems to work.  Note that this only changes the passed path; any
> pathmunge()'ing in the chroot's startup scripts still happens.  I've
> already fixed the problem inside the chroot, but I'll set this up if
> I find another problematic chroot.  It should be OK to look at
> /usr/bin twice if /bin -> /usr/bin and the command doesn't exist.

If the pathmunging is done in a "//etc/..." script
or in a "~/.whatever", absolutely as that is done after the chroot
spawns the shell in the chrooted environment. If you're saying it
happens before the chroot, then I don't know how that'd occur.

I think the issue you've been having is that your chroot environment
doesn't have the merged /bin and /usr/bin. It has separate /bin and
/usr/bin directories. After the merge of /bin and /usr/bin was
established, I believe bash's built-in default PATH was modified to
assume this symlink was done. That's why the new bash doesn't have a
separate "/bin" in its default path.
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Re: f26 chroot PATH doesn't include /bin

[Tony Nelson]

On 17-08-31 12:41:09, Mike Wright wrote:


How about using "env":  env PATH="new_path" chroot /some_dir

Wouldn't this preempt the passed PATH, profile, bashrc, and the dot  
files?  If so, chroot could be defined as an alias to "env ...  
chroot" and thereby eliminate the problem.


Seems to work.  Note that this only changes the passed path; any
pathmunge()'ing in the chroot's startup scripts still happens.  I've
already fixed the problem inside the chroot, but I'll set this up if
I find another problematic chroot.  It should be OK to look at
/usr/bin twice if /bin -> /usr/bin and the command doesn't exist.

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Re: f26 chroot PATH doesn't include /bin

[Tony Nelson]

On 17-08-31 12:18:38, Tom H wrote:

On Wed, Aug 30, 2017 at 3:16 PM, Tony Nelson
 wrote:
>
> I have an old CentOS5 that I chroot into. On my old f20 box, PATH
> included /bin, but now on f26 it does not. I don't understand how
> this could happen; I would think that PATH is set inside the chroot
> by the shell. How does PATH get set? I see how it is modified and
> have fixed my issue, provided I use a login shell.

It's because chroot keeps PATH set. So if your pre-chroot PATH doesn't
include "/sbin" or "/bin", they won't be in the chrooted PATH:


OK, now I get it.  I have another chroot for f20, which is after the
/bin -> /usr/bin transition, that works because it doesn't need any  
help.


 ...

If you use a login shell (eg, "chroot /bb bash -l" instead of "chroot
/bb bash"), the dotfiles that will be sourced will set the appropriate
chrooted PATH.


Sadly, no, not without editing them.  The only pathmunge()'ing I see is
for root's use of sbin.  I added a file to /etc/profile.d to pathmunge
/bin, which sets the path for both interactive and login shells.

I still have an issue of no saved history on plain interactive shells,
so I do specify a login shell.  My f20 chroot doesn't have the problem,
either as a login shell or not as shown by `shopt login_shell`, but
it's a more complicated (overlayfs over ro mount) setup, as well as
newer than the CentOS5 setup.

The history issue with CentOS5 chroot is new with f26, and worked in
f20.

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Re: f26 chroot PATH doesn't include /bin

[Rick Stevens]

On 08/31/2017 09:41 AM, Mike Wright wrote:
> On 08/31/2017 09:26 AM, Rick Stevens wrote:
>> On 08/31/2017 08:34 AM, Kevin Cummings wrote:
>>> On 08/30/17 15:16, Tony Nelson wrote:
 I have an old CentOS5 that I chroot into.  On my old f20 box, PATH
 included /bin, but now on f26 it does not.  I don't understand how
>>>
>>> For a while now, /bin should be a link to /usr/bin.  is /usr/bin in the
>>> PATH?
>>
>> That's the most likely issue here. The OP keeps referring to an F20
>> box and IIRC that predates the /bin<-->/usr/bin changeover.
>>
>> To answer the question, bash has an initial PATH compiled into it.
>> What that PATH contains depends on how bash was built and how bash
>> was launched (they inherit the environment of the launching process--
>> interactive or not). The vast majority of systems bugger that default
>> path by use of the /etc/bashrc script and possibly custom scripts in
>> /etc/profile.d.
>>
>> Interactive (login) shells are typically launched by the login process
>> and inherit the login process' PATH (see "man login" for details). The
>> additional stuff (/etc/bashrc, /etc/profile, etc.) are also invoked.
>>
>> A chrooted shell gets its environment from the chroot process and would
>> run any normal startup scripts, but they'd be from the chrooted /etc,
>> not necessarily the root system's /etc.
> 
> How about using "env":  env PATH="new_path" chroot /some_dir
> 
> Wouldn't this preempt the passed PATH, profile, bashrc, and the dot
> files?  If so, chroot could be defined as an alias to "env ... chroot"
> and thereby eliminate the problem.

I suppose you could:

env PATH="/bin:/sbin:/usr/bin:/usr/sbin" chroot /some_dir

Remember that the chrooted shell would be looking for the directories in
the "PATH=" under "/some_dir", since the shell would rooted there.

Chroot jails can be complex to set up. You need all the utilities you
need in the chroot along with their required libraries, etc., etc.
It might be better to look at things like sandboxes (based on selinux),
lxc (linux containers) or firejail (based on linux namespaces and other
goodies).

Oh, wow, my brain is starting to cramp on this. :p
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Re: f26 chroot PATH doesn't include /bin

[Mike Wright]

On 08/31/2017 09:26 AM, Rick Stevens wrote:

On 08/31/2017 08:34 AM, Kevin Cummings wrote:

On 08/30/17 15:16, Tony Nelson wrote:

I have an old CentOS5 that I chroot into.  On my old f20 box, PATH
included /bin, but now on f26 it does not.  I don't understand how


For a while now, /bin should be a link to /usr/bin.  is /usr/bin in the
PATH?


That's the most likely issue here. The OP keeps referring to an F20
box and IIRC that predates the /bin<-->/usr/bin changeover.

To answer the question, bash has an initial PATH compiled into it.
What that PATH contains depends on how bash was built and how bash
was launched (they inherit the environment of the launching process--
interactive or not). The vast majority of systems bugger that default
path by use of the /etc/bashrc script and possibly custom scripts in
/etc/profile.d.

Interactive (login) shells are typically launched by the login process
and inherit the login process' PATH (see "man login" for details). The
additional stuff (/etc/bashrc, /etc/profile, etc.) are also invoked.

A chrooted shell gets its environment from the chroot process and would
run any normal startup scripts, but they'd be from the chrooted /etc,
not necessarily the root system's /etc.


How about using "env":  env PATH="new_path" chroot /some_dir

Wouldn't this preempt the passed PATH, profile, bashrc, and the dot 
files?  If so, chroot could be defined as an alias to "env ... chroot" 
and thereby eliminate the problem.





this could happen; I would think that PATH is set inside the chroot
by the shell.  How does PATH get set?  I see how it is modified and
have fixed my issue, provided I use a login shell.

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Re: f26 chroot PATH doesn't include /bin

[Rick Stevens]

On 08/31/2017 08:34 AM, Kevin Cummings wrote:
> On 08/30/17 15:16, Tony Nelson wrote:
>> I have an old CentOS5 that I chroot into.  On my old f20 box, PATH
>> included /bin, but now on f26 it does not.  I don't understand how
> 
> For a while now, /bin should be a link to /usr/bin.  is /usr/bin in the
> PATH?

That's the most likely issue here. The OP keeps referring to an F20
box and IIRC that predates the /bin<-->/usr/bin changeover.

To answer the question, bash has an initial PATH compiled into it.
What that PATH contains depends on how bash was built and how bash
was launched (they inherit the environment of the launching process--
interactive or not). The vast majority of systems bugger that default
path by use of the /etc/bashrc script and possibly custom scripts in
/etc/profile.d.

Interactive (login) shells are typically launched by the login process
and inherit the login process' PATH (see "man login" for details). The
additional stuff (/etc/bashrc, /etc/profile, etc.) are also invoked.

A chrooted shell gets its environment from the chroot process and would
run any normal startup scripts, but they'd be from the chrooted /etc,
not necessarily the root system's /etc.

>> this could happen; I would think that PATH is set inside the chroot
>> by the shell.  How does PATH get set?  I see how it is modified and
>> have fixed my issue, provided I use a login shell.
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Re: f26 chroot PATH doesn't include /bin

[Tom H]

On Thu, Aug 31, 2017 at 11:34 AM, Kevin Cummings
 wrote:
> On 08/30/17 15:16, Tony Nelson wrote:
>>
>> I have an old CentOS5 that I chroot into. On my old f20 box, PATH
>> included /bin, but now on f26 it does not. I don't understand how
>
> For a while now, /bin should be a link to /usr/bin. is /usr/bin in the
> PATH?

On CentOS 5, /bin, /lib, /sbin aren't symlinks to their /usr
counterparts; that was done with CentOS 7.
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Re: f26 chroot PATH doesn't include /bin

[Tom H]

On Wed, Aug 30, 2017 at 3:16 PM, Tony Nelson
 wrote:
>
> I have an old CentOS5 that I chroot into. On my old f20 box, PATH
> included /bin, but now on f26 it does not. I don't understand how
> this could happen; I would think that PATH is set inside the chroot
> by the shell. How does PATH get set? I see how it is modified and
> have fixed my issue, provided I use a login shell.

It's because chroot keeps PATH set. So if your pre-chroot PATH doesn't
include "/sbin" or "/bin", they won't be in the chrooted PATH:

root@fedraw ~ # echo $PATH
/usr/sbin:/usr/bin

root@fedraw ~ # chroot /bb ./busybox sh

\u@\h \w # echo $PATH
/usr/sbin:/usr/bin

\u@\h \w # exit

root@fedraw ~ # PATH=/sbin:/bin:/usr/sbin:/usr/bin chroot /bb ./busybox sh

\u@\h \w # echo $PATH
/sbin:/bin:/usr/sbin:/usr/bin

\u@\h \w # exit

root@fedraw ~ #

If you use a login shell (eg, "chroot /bb bash -l" instead of "chroot
/bb bash"), the dotfiles that will be sourced will set the appropriate
chrooted PATH.
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Re: f26 chroot PATH doesn't include /bin

[Kevin Cummings]

On 08/30/17 15:16, Tony Nelson wrote:
> I have an old CentOS5 that I chroot into.  On my old f20 box, PATH
> included /bin, but now on f26 it does not.  I don't understand how

For a while now, /bin should be a link to /usr/bin.  is /usr/bin in the
PATH?

> this could happen; I would think that PATH is set inside the chroot
> by the shell.  How does PATH get set?  I see how it is modified and
> have fixed my issue, provided I use a login shell.
> 

-- 
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cummi...@kjchome.homeip.net
cummi...@kjc386.framingham.ma.us
kjch...@icloud.com
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f26 chroot PATH doesn't include /bin

[Tony Nelson]

I have an old CentOS5 that I chroot into.  On my old f20 box, PATH
included /bin, but now on f26 it does not.  I don't understand how
this could happen; I would think that PATH is set inside the chroot
by the shell.  How does PATH get set?  I see how it is modified and
have fixed my issue, provided I use a login shell.

--

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  '  
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