selinux November 2019

selinux@lists.fedoraproject.org

5 participants
5 discussions

selinux strange behaviour
by Michel Gravier 18 Nov '19

18 Nov '19

Dear all I try to forbid execution of script on user home by standard user. Here what I have done : Change the boolean user_exec_content to off : # setsebool user_exec_content off So if i read policies any process with the user_t domain should not be able to exec a file with user_home_t type ? So i create a user "toto" with the context : $ id -Z user_u:user_r:user_t:s0 I create a bash script "test.sh" with 2 lines : #!/bin/bash ps -fZ $ ll -Z total 3 -rwxr-xr-x. 1 toto toto user_u:object_r:user_home_t:s0 19 15 nov. 08:00 test.sh When i try to execute de script : $ ./test.sh -bash: ./test.sh: Permission denied That's what I wanted. And it's SELinux which do the work : # tail -3 /var/log/audit/audit.log type=AVC msg=audit(1573824552.173:265): avc: denied { execute } for pid=15138 comm="bash" name="test.sh" dev="dm-0" ino=341980 scontext=user_u:user_r:user_t:s0 tcontext=user_u:object_r:user_home_t:s0 tclass=file permissive=0 type=SYSCALL msg=audit(1573824552.173:265): arch=c000003e syscall=59 success=no exit=-13 a0=55ed16979130 a1=55ed169ad730 a2=55ed169856c0 a3=8 items=0 ppid=14703 pid=15138 auid=1000 uid=1000 gid=1000 euid=1000 suid=1000 fsuid=1000 egid=1000 sgid=1000 fsgid=1000 tty=pts1 ses=9 comm="bash" exe="/usr/bin/bash" subj=user_u:user_r:user_t:s0 key=(null)ARCH=x86_64 SYSCALL=execve AUID="toto" UID="toto" GID="toto" EUID="toto" SUID="toto" FSUID="toto" EGID="toto" SGID="toto" FSGID="toto" type=PROCTITLE msg=audit(1573824552.173:265): proctitle="-bash" But if I do this : $ bash test.sh LABEL UID PID PPID C STIME TTY TIME CMD user_u:user_r:user_t:s0 toto 14703 14702 0 08:00 pts/1 00:00:00 -bash user_u:user_r:user_t:s0 toto 15147 14703 0 08:31 pts/1 00:00:00 bash test.sh user_u:user_r:user_t:s0 toto 15148 15147 0 08:31 pts/1 00:00:00 ps -fZ I'm quite surprise of the result !? Why the second bash (pid 15147) is authorized to execute "test.sh" ? Thanks for your attention.

3 2

Re: using an interface defined in another loaded module
by SZIGETVÁRI János 07 Nov '19

07 Nov '19

Dear Gary, Thanks a zillion times for your help, the building of the policy works fine now that I have copied the .if file of the submodule to the directory you mentioned! I did not know I was reqired to copy the module's interface file to SELinux's include dirs to make it available for other modules to use. BTW, I was building my module from within my "policy builder and installer" script using the "traditional" way of: # make -f /usr/share/selinux/devel/Makefile A.pp Now the build process works, thanks to your suggestion! Best Regards, János -- Janos SZIGETVARI RHCE, License no. 150-053-692 <https://www.redhat.com/rhtapps/verify/?certId=150-053-692> LinkedIn: linkedin.com/in/janosszigetvari E-mail: janos(a)szigetvari.com, jszigetvari(a)gmail.com Phone: +36209440412 (Hungary) __@__˚V˚ Make the switch to open (source) applications, protocols, formats now: - windows -> Linux, iexplore -> Firefox, msoffice -> LibreOffice - msn -> jabber protocol (Pidgin, Google Talk) - mp3 -> ogg, wmv -> ogg, jpg -> png, doc/xls/ppt -> odt/ods/odp Gary Tierney <gary.tierney(a)gmx.com> ezt írta (időpont: 2019. ápr. 3., Sze, 17:14): > On Wed, Apr 03, 2019 at 10:34:08AM +0200, SZIGETVÁRI János wrote: > >Could anyone please give me some insight on this? > > > >Thanks a lot! > > > > Hi, > > How are you building and installing your policy modules? The interface > definitions (.if files) aren't preserved in the compiled policy package, > so are typically kept elsewhere. On Fedora this is under > /usr/share/selinux/devel/include and its associated subdirectories > (which are recursively walked to find .if files when building policy > using the refpolicy framework, i.e., the selinux-policy-devel package). > > So it should be as simple as copying your .if files to: > /usr/share/selinux/devel/include (though the "services" subdir is likely > more appropriate). > > Thanks, > Gary. > > >Best Regards, > >János Szigetvári > > > >SZIGETVÁRI János <jszigetvari(a)gmail.com> ezt írta (időpont: 2019. márc. > >31., V, 13:47): > > > >> ... snip ... > >_______________________________________________ > >selinux mailing list -- selinux(a)lists.fedoraproject.org > >To unsubscribe send an email to selinux-leave(a)lists.fedoraproject.org > >Fedora Code of Conduct: https://getfedora.org/code-of-conduct.html > >List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines > >List Archives: > https://lists.fedoraproject.org/archives/list/selinux@lists.fedoraproject.o… > >

4 9

Can't change SELinux user home directory file owner
by arnaud gaboury 06 Nov '19

06 Nov '19

Looking at more closer at my SELinux settings (Fedora 29 Atomic), I found this: ---------- semanage login -l Login Name SELinux User MLS/MCS Range Service __default__ unconfined_u s0-s0:c0.c1023 * root system_u s0:c0.c1023 * ------------------------------------- I can’t remember if I did the change, but following RedHat or Fedora documentation, root should be an unconfined user, right? So I did the change this way: ----------------------------------------------------- # semanage login -m -s unconfined_u -rs0:c0.c1023 root # semanage login -l ... root unconfined_u s0:c0.c1023 * # id -Z unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 ---------------------------------------------------------- Fine. Now let's list the root directory: -------------------------------------------- # pwd /var/roothome # ls -alZ .... -rw-r--r--. 1 root root system_u:object_r:admin_home_t:s0 18 May 28 2018 .bash_logout -rw-r--r--. 1 root root system_u:object_r:admin_home_t:s0 193 May 28 2018 .bash_profile -rw-r--r--. 1 root root system_u:object_r:admin_home_t:s0 231 May 28 2018 .bashrc .... ------------------------------------------------- I thus wanted to change system_u to unconfined_u (Do I need to do it?) ------------------------------------------------------- # semanage fcontext -m -t admin_home_t -s unconfined_u "/var/roothome(/.*)?" ValueError: File context for /var/roothome(/.*)? is not defined # semanage fcontext -a -t admin_home_t -s unconfined_u "/var/roothome(/.*)?" # cat /etc/selinux/targeted/contexts/files/file_contexts.local .... /var/roothome(/.*)? unconfined_u:object_r:admin_home_t:s0 <-- sounds OK # restorecon -R -v /var/roothome # ls -alZ ... -rw-r--r--. 1 root root system_u:object_r:admin_home_t:s0 193 May 28 2018 .bash_profile -rw-r--r--. 1 root root system_u:object_r:admin_home_t:s0 231 May 28 2018 .bashrc ... ----------------------------------------------------- No changes. Why? Do I need to change to unconfined user, and if yes, how? Thank you for help.

1 0

Re: Reg: domain transition
by Lukas Vrabec 01 Nov '19

01 Nov '19

On 11/1/19 5:48 AM, zer0 0ne wrote: > I am writing SELinux policies for the first time and I need some > clarification > > > > 1. I have executable A executes a system() call, spawns a shell and > executes a command ‘B’ and consumes the output of command B. Do I > have to use domain transition in the above case or what is the > correct way to go about it?> 2. In the above case A and B have different SELinux policies. Since A > executes B, in SELinux policy of A do I need to make type B_t as a > required type? > 3. For process A to do domain_transition to B, do I add > b_domain_transition macro in A.if file or in A.te > > I believe you can find answers in this blog: https://danwalsh.livejournal.com/72287.html Thanks, Lukas. > TiA > > zer0 0ne > > > > _______________________________________________ > selinux mailing list -- selinux(a)lists.fedoraproject.org > To unsubscribe send an email to selinux-leave(a)lists.fedoraproject.org > Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ > List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines > List Archives: https://lists.fedoraproject.org/archives/list/selinux@lists.fedoraproject.o… > -- Lukas Vrabec SELinux Evangelist, Senior Software Engineer, Security Technologies Red Hat, Inc.

1 0

Reg: domain transition
by zer0 0ne 31 Oct '19

31 Oct '19

I am writing SELinux policies for the first time and I need some clarification 1. I have executable A executes a system() call, spawns a shell and executes a command ‘B’ and consumes the output of command B. Do I have to use domain transition in the above case or what is the correct way to go about it? 2. In the above case A and B have different SELinux policies. Since A executes B, in SELinux policy of A do I need to make type B_t as a required type? 3. For process A to do domain_transition to B, do I add b_domain_transition macro in A.if file or in A.te TiA zer0 0ne

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selinux November 2019