Re: permission problems with script run via crondargs -m

[Robert Moskowitz]

On 5/12/20 11:36 AM, Lukas Vrabec wrote:
> On 5/12/20 1:31 PM, Robert Moskowitz wrote:
> > Lukas,
> >
> > Failed again last night see the end of this message.
> >
> > On 5/11/20 9:40 AM, Lukas Vrabec wrote:
> > > On 5/11/20 3:19 PM, Robert Moskowitz wrote:
> > > > On 5/11/20 9:04 AM, Lukas Vrabec wrote:
> > > > > On 5/11/20 2:23 PM, Robert Moskowitz wrote:
> > > > > > A little background first.
> > > > > >
> > > > > > This is for Fedora 32 workstation which does not come with a
> > > > > > default MTA
> > > > > > and thus there is a slight challenge (ahem) getting CRON's output into
> > > > > > the local mailstore.  I don't want to install an MTA (leave why for
> > > > > > Fedora users list discuss) and "procmail -f cron" leaves out a DATE
> > > > > > header.  So I wrote my own little script that I put in
> > > > > > /usr/local/mycron
> > > > > > that takes the output from cron and appends the proper content to
> > > > > > /var/spool/mail/$USER.
> > > > > >
> > > > > > Works fine for my personal crontab, but has selinux problems for
> > > > > > logwatch running as root (and probably any other cron task running as
> > > > > > root).
> > > > > >
> > > > > > So I first got told by selinux troubleshooting that I needed:
> > > > > >
> > > > > > ausearch -c 'mycron' --raw | audit2allow -M my-mycron
> > > > > > semodule -X 300 -i my-mycron.pp
> > > > > >
> > > > > > Which I did.  Then after this night's run of logwatch, I see that I
> > > > > > have
> > > > > > the selinux troubleshoot icon, but when I look, it is empty? So I grep
> > > > > > messages for logwatch, then grep the time it was running and found the
> > > > > > following:
> > > > > >
> > > > > > May 11 03:43:19 lx140e setroubleshoot[121345]: SELinux is preventing
> > > > > > mycron from add_name
> > > > > > access on the directory root. For complete SELinux messages run:
> > > > > > sealert
> > > > > > -l 8eb93a73-c7ff-
> > > > > > 42ec-bee1-594d77540808
> > > > > > May 11 03:43:19 lx140e python3[121345]: SELinux is preventing mycron
> > > > > > from add_name access
> > > > > > on the directory root.#012#012*****  Plugin catchall (100. confidence)
> > > > > > suggests   ********
> > > > > > ******************#012#012If you believe that mycron should be allowed
> > > > > > add_name access on
> > > > > > the root directory by default.#012Then you should report this as a
> > > > > > bug.#012You can generat
> > > > > > e a local policy module to allow this access.#012Do#012allow this
> > > > > > access
> > > > > > for now by execut
> > > > > > ing:#012# ausearch -c 'mycron' --raw | audit2allow -M my-mycron#012#
> > > > > > semodule -X 300 -i my
> > > > > > -mycron.pp#012
> > > > > > May 11 03:43:23 lx140e systemd[1]:
> > > > > > dbus-:[e-mail]:
> > > > > >     Succeeded.
> > > > > >
> > > > > > So it looks like now I am told to run:
> > > > > >
> > > > > > ausearch -c 'mycron' --raw | audit2allow -M my-mycron
> > > > > > semodule -X 300 -i my-mycron.pp
> > > > > >
> > > > > > Wait, that is the same I ran earlier?  And why did I have to grep
> > > > > > messages to find these?
> > > > >
> > > > > Hi,
> > > > >
> > > > > Could you please share output of this command:
> > > > >
> > > > > # sealert -l 8eb93a73-c7ff-42ec-bee1-594d77540808
> > > >
> > > > # sealert -l 8eb93a73-c7ff-42ec-bee1-594d77540808
> > > > Error
> > > > query_alerts error (1003): id (8eb93a73-c7ff-42ec-bee1-594d77540808) not
> > > > found
> > > >
> > > > And from the first selinux alert:
> > > >
> > > > # sealert -l d05d8373-fae7-447e-b45a-74940959809e
> > > > Error
> > > > query_alerts error (1003): id (d05d8373-fae7-447e-b45a-74940959809e) not
> > > > found
> > > >
> > > > I viewed the alerts with the SELinux troubleshooter, but I did NOT tell
> > > > it to delete the alert :(
> > >
> > > No problem, are you able to reproduce it? If yes, please do and then
> > > attach:
> > >
> > > # ausearch -m AVC,USER_AVC -ts today
> > # ausearch -m AVC,USER_AVC -ts today
> >
> > time->Tue May 12 03:22:06 2020
> > type=AVC msg=audit(1589268126.630:3796): avc:  denied  { add_name } for
> > pid=142359 comm="mycron" name="root"
> > scontext=system_u:system_r:logwatch_t:s0-s0:c0.c1023
> > tcontext=system_u:object_r:mail_spool_t:s0 tclass=dir permissive=0
> >
> > May 12 03:22:06 lx140e audit[142359]: AVC avc:  denied  { add_name }
> > for  pid=142359 comm="mycron" name="root"
> > scontext=system_u:system_r:logwatch_t:s0-s0:c0.c1023
> > tcontext=system_u:object_r:mail_spool_t:s0 tclass=dir permissive=0
> > May 12 03:22:09 lx140e systemd[1]: Started
> > dbus-:[e-mail].
> > May 12 03:22:09 lx140e audit[1]: SERVICE_START pid=1 uid=0
> > auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0
> > msg='unit=dbus-:1.1-org.fedoraproject.Setroubleshootd@20 comm="systemd"
> > exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=success'
> > May 12 03:22:13 lx140e systemd[1]: Started
> > dbus-:[e-mail].
> > May 12 03:22:13 lx140e audit[1]: SERVICE_START pid=1 uid=0
> > auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0
> > msg='unit=dbus-:1.1-org.fedoraproject.SetroubleshootPrivileged@10
> > comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=?
> > terminal=? res=success'
> > May 12 03:22:19 lx140e setroubleshoot[142374]: SELinux is preventing
> > mycron from add_name access on the directory root. For complete SELinux
> > messages run: sealert -l 9fd5890f-400b-4ae0-8a98-43575ac4913a
> > May 12 03:22:19 lx140e python3[142374]: SELinux is preventing mycron
> > from add_name access on the directory root.#012#012*****  Plugin
> > catchall (100. confidence) suggests **************************#012#012If
> > you believe that mycron should be allowed add_name access on the root
> > directory by default.#012Then you should report this as a bug.#012You
> > can generate a local policy module to allow this access.#012Do#012allow
> > this access for now by executing:#012# ausearch -c 'mycron' --raw |
> > audit2allow -M my-mycron#012# semodule -X 300 -i my-mycron.pp#012
> > May 12 03:22:23 lx140e systemd[1]:
> > dbus-:[e-mail]: Succeeded.
> > May 12 03:22:23 lx140e audit[1]: SERVICE_STOP pid=1 uid=0
> > auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0
> > msg='unit=dbus-:1.1-org.fedoraproject.Setroubleshootd@20 comm="systemd"
> > exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=success'
> > May 12 03:22:23 lx140e systemd[1]:
> > dbus-:[e-mail]: Consumed 3.306s
> > CPU time.
> > May 12 03:22:25 lx140e systemd[1]:
> > dbus-:[e-mail]: Succeeded.
> > May 12 03:22:25 lx140e audit[1]: SERVICE_STOP pid=1 uid=0
> > auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0
> > msg='unit=dbus-:1.1-org.fedoraproject.SetroubleshootPrivileged@10
> > comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=?
> > terminal=? res=success'
> > May 12 03:22:25 lx140e systemd[1]:
> > dbus-:[e-mail]:
> > Consumed 5.271s CPU time.
> >
> > # sealert -l 9fd5890f-400b-4ae0-8a98-43575ac4913a
> > Error
> > query_alerts error (1003): id (9fd5890f-400b-4ae0-8a98-43575ac4913a) not
> > found
>
> Can you attach your "mycron" script? THere is some issue with SELinux
> domain transition.

I just made a few improvements to it, but here is what ran last night:

local]# cat mycron
#!/bin/sh

# the sed commands only work if USER == MAILTO in crontab

exec 3>> /var/spool/mail/$USER
exec 100>/var/tmp/$USERlock.lock || exit 1
flock -w 120 100 || exit 1
currentDate=$(date +'%a %b %d %T %Y')
echo "From cron@localhost  $currentDate" >&3
currentDate2=$(date +'%a, %e %b %Y %T %z (%Z)')
echo "Date: $currentDate2" >&3
echo "Message-ID: $(uuidgen)@$HOSTNAME" >&3
# (cat) >&3
(sed  -e "/^From: / s/$USER/$USER@$HOSTNAME/"|sed  -e "/^To: / 
s/$USER/$USER@$HOSTNAME/") >&3
echo "" >&3

The flock stuff was added yesterday, and was not in the previous failures.