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$*USER and $*GROUP don't update when uid/gid change #4728

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p6rt opened this issue Nov 4, 2015 · 4 comments
Open

$*USER and $*GROUP don't update when uid/gid change #4728

p6rt opened this issue Nov 4, 2015 · 4 comments
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@p6rt p6rt commented Nov 4, 2015

Migrated from rt.perl.org#126560 (status was 'open')

Searchable as RT126560$

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@p6rt p6rt commented Nov 4, 2015

From @cspencer

I recently committed the starts of a POSIX module to the p6 ecosystem and noticed that when using the POSIX​::setuid and POSIX​::setgid function calls, the $*USER and $*GROUP variables to not update as expected when program privileges change.

I have attached a sample program demonstrating this below. Note that the program must be run as root.

Here is the output on my machine​:

~$ sudo perl6 ./uid-gid.p6
$*USER reports UID as​: 0
$*GROUP reports GID as​: 0

POSIX​::getuid reports UID as​: 0
POSIX​::getgid reports GID as​: 0

Dropping privileges to 'nobody' user...

Privileges dropped.

$*USER reports UID as​: 0
$*GROUP reports GID as​: 0

POSIX​::getuid reports UID as​: 65534
POSIX​::getgid reports GID as​: 65534

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@p6rt p6rt commented Nov 4, 2015

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@p6rt p6rt commented Nov 6, 2015

From @lizmat

On 04 Nov 2015, at 01​:53, Cory Spencer (via RT) <perl6-bugs-followup@​perl.org> wrote​:

# New Ticket Created by Cory Spencer
# Please include the string​: [perl #​126560]
# in the subject line of all future correspondence about this issue.
# <URL​: https://rt-archive.perl.org/perl6/Ticket/Display.html?id=126560 >

I recently committed the starts of a POSIX module to the p6 ecosystem and noticed that when using the POSIX​::setuid and POSIX​::setgid function calls, the $*USER and $*GROUP variables to not update as expected when program privileges change.

I have attached a sample program demonstrating this below. Note that the program must be run as root.

Here is the output on my machine​:

~$ sudo perl6 ./uid-gid.p6
$*USER reports UID as​: 0
$*GROUP reports GID as​: 0

POSIX​::getuid reports UID as​: 0
POSIX​::getgid reports GID as​: 0

Dropping privileges to 'nobody' user...

Privileges dropped.

$*USER reports UID as​: 0
$*GROUP reports GID as​: 0

POSIX​::getuid reports UID as​: 65534
POSIX​::getgid reports GID as​: 65534

<uid-gid.p6>

The default implementation of $*USER and $*GROUP call an external program and parses the result at the moment. This is something you do not want to do for every access to $*USER.

I recommend that the POSIX module installs its own version of $*USER / $*GROUP handling in PROCESS​::<$USER> and PROCESS​::<$GROUP>, which can then correctly reflect changes in privileges. Something akin to​:

PROCESS​::<$USER> := POSIX​::getuid;
PROCESS​::<$GROUP> := POSIX​::getgid;

My advise​: ENOTABUG, can be closed.

Liz

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@p6rt p6rt commented Nov 6, 2015

The RT System itself - Status changed from 'new' to 'open'

@p6rt p6rt added the RFC label Jan 5, 2020
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