From: sven.vermeulen@siphos.be (Sven Vermeulen) Date: Wed, 20 Mar 2013 10:03:17 +0100 Subject: [refpolicy] [PATCH 1/1] chfn_t reads in file context information and executes nscd Message-ID: <20130320090317.GA12451@siphos.be> To: refpolicy@oss.tresys.com List-Id: refpolicy.oss.tresys.com The chsh application (which runs in the chfn_t domain) requires read access on the file context definitions. If not, the following error occurs: Changing the login shell for root Enter the new value, or press ENTER for the default Login Shell [/bin/zsh]: /bin/bash chsh: failure while writing changes to /etc/passwd The following AVC denials are shown: Jan 23 20:23:43 lain kernel: [20378.806719] type=1400 audit(1358969023.507:585): avc: denied { search } for pid=18281 comm="chsh" name="selinux" dev="dm-0" ino=23724520 scontext=staff_u:sysadm_r:chfn_t tcontext=system_u:object_r:selinux_config_t tclass=dir In permissive mode, this goes up to: Jan 23 20:22:15 lain kernel: [20290.691128] type=1400 audit(1358968935.217:566): avc: denied { open } for pid=18195 comm="chsh" path="/etc/selinux/strict/contexts/files/file_contexts" dev="dm-0" ino=23726403 scontext=staff_u:sysadm_r:chfn_t tcontext=staff_u:object_r:file_context_t tclass=file Hence, adding in seutil_read_file_contexts(). A second error is that chsh, if available, wants to execute nscd: Changing the login shell for root Enter the new value, or press ENTER for the default Login Shell [/bin/sh]: /bin/bash chsh: cannot execute /usr/sbin/nscd: Permission denied chsh: nscd exited with status 126 chsh: Failed to flush the nscd cache. chsh: cannot execute /usr/sbin/nscd: Permission denied chsh: nscd exited with status 126 chsh: Failed to flush the nscd cache. chsh: cannot execute /usr/sbin/nscd: Permission denied chsh: nscd exited with status 126 chsh: Failed to flush the nscd cache. Similar to most other user admin utilities, we grant it the rights to run nscd. Signed-off-by: Sven Vermeulen --- policy/modules/admin/usermanage.te | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/policy/modules/admin/usermanage.te b/policy/modules/admin/usermanage.te index d555767..774d8c3 100644 --- a/policy/modules/admin/usermanage.te +++ b/policy/modules/admin/usermanage.te @@ -125,6 +125,7 @@ miscfiles_read_localization(chfn_t) logging_send_syslog_msg(chfn_t) +seutil_read_file_contexts(chfn_t) # uses unix_chkpwd for checking passwords seutil_dontaudit_search_config(chfn_t) @@ -133,6 +134,10 @@ userdom_use_unpriv_users_fds(chfn_t) # on user home dir userdom_dontaudit_search_user_home_content(chfn_t) +optional_policy(` + nscd_run(chfn_t, chfn_roles) +') + ######################################## # # Crack local policy -- 1.8.1.5