From: guido@trentalancia.com (Guido Trentalancia) Date: Wed, 29 Aug 2012 17:37:53 +0200 Subject: [refpolicy] [PATCH 1/2]: cpucontrol module updates (stricter policy for CPU microcode updates) In-Reply-To: <503E136A.5070102@tresys.com> References: <5037897A.5050305@trentalancia.com> <503E136A.5070102@tresys.com> Message-ID: <503E3751.20704@trentalancia.com> To: refpolicy@oss.tresys.com List-Id: refpolicy.oss.tresys.com On 29/08/2012 15:04, Christopher J. PeBenito wrote: > On 08/24/12 10:02, Guido Trentalancia wrote: >> cpucontrol module updates: >> - introduce the file contexts according to the standard location >> of the most common application named microcode_ctl >> (http://www.urbanmyth.org/microcode); >> - add file contexts for CPUs from two different vendors, taking >> into consideration specific customization of the location >> for one distribution; >> - add file contexts and declarations for the init script; >> - introduce the ability to update the CPU microcode as >> tunable policy, as apparently such operation might >> modify the original licensing conditions (under some or >> all circumstances: "personal, non-commercial use only"); >> - create a new device type specifically for the CPU microcode >> updating functionality and modify the cpucontrol module so >> that such distinct new type is used for the microcode >> updating operation, thus leaving an open door for further >> modifications that distinguish different CPU-related >> applications/utilities to create further isolation; >> - modify the interface definitions so that the CPU microcode >> update utility can only write and not read (unneeded) the >> corresponding above mentioned device type. >> >> Signed-off-by: Guido Trentalancia >> --- >> policy/modules/contrib/cpucontrol.fc | 18 +++++++++- >> policy/modules/contrib/cpucontrol.te | 16 ++++++++- >> policy/modules/kernel/devices.fc | 3 + >> policy/modules/kernel/devices.if | 62 >> +++++++++++++++++++++++++++++++---- >> policy/modules/kernel/devices.te | 8 +++- >> 5 files changed, 96 insertions(+), 11 deletions(-) >> >> diff -pruN refpolicy-08082012/policy/modules/contrib/cpucontrol.fc >> refpolicy-08082012-microcode/policy/modules/contrib/cpucontrol.fc >> --- refpolicy-08082012/policy/modules/contrib/cpucontrol.fc 2011-09-09 >> 18:29:23.563610858 +0200 >> +++ refpolicy-08082012-microcode/policy/modules/contrib/cpucontrol.fc >> 2012-08-09 01:13:59.615119168 +0200 >> @@ -1,7 +1,23 @@ >> +/etc/microcode\.dat -- gen_context(system_u:object_r:cpucontrol_conf_t,s0) >> +/etc/microcode_amd\.bin -- >> gen_context(system_u:object_r:cpucontrol_conf_t,s0) >> +/etc/firmware/microcode\.dat -- >> gen_context(system_u:object_r:cpucontrol_conf_t,s0) >> +/etc/firmware/microcode_amd.bin -- >> gen_context(system_u:object_r:cpucontrol_conf_t,s0) >> >> -/etc/firmware/.* -- gen_context(system_u:object_r:cpucontrol_conf_t,s0) >> +/etc/rc\.d/init\.d/microcode -- >> gen_context(system_u:object_r:cpucontrol_initrc_exec_t,s0) >> >> +ifdef(`distro_redhat',` >> +/lib/firmware/intel-ucode(/.*)? >> gen_context(system_u:object_r:cpucontrol_conf_t,s0) >> +/lib/firmware/amd-ucode(/.*)? >> gen_context(system_u:object_r:cpucontrol_conf_t,s0) >> +/lib/firmware/microcode\.dat -- >> gen_context(system_u:object_r:cpucontrol_conf_t,s0) >> +/lib/firmware/microcode_amd\.bat -- >> gen_context(system_u:object_r:cpucontrol_conf_t,s0) >> +') > > I'm conflicted. I assume that the /etc/microcode and /etc/firmware locations are the default for this app, /lib/firmware seems more appropriate. I suspect this is not a redhat-specific location. As far as I remember the /etc/firmware location was originally chosen by one distribution (maybe Fedora, I can't remember exactly the details). If that is removed, it might break compatibility with previous releases. Latest location chosen by Fedora should probably be /lib/firmware with the variants included in the ifdef distro block. >> +/usr/sbin/microcode_ctl -- >> gen_context(system_u:object_r:cpucontrol_exec_t,s0) >> +/usr/local/sbin/microcode_ctl -- >> gen_context(system_u:object_r:cpucontrol_exec_t,s0) > > The /usr/local label is not necessary, as it will be handled by the file context path substitutions. I wasn't sure how to proceed, /usr/local/sbin is the original default location chosen by the unedited application's Makefile... As for the other vendor, the specific application should be called "ucodeadm" and I've included that with the /usr/sbin prefix in the next version of the patch that I am preparing. >> +ifdef(`distro_redhat',` >> /sbin/microcode_ctl -- gen_context(system_u:object_r:cpucontrol_exec_t,s0) >> +') > > I also don't think this change is really necessary. I don't know. It probably got there from some brief research carried out on recent Fedora builds... But, if it's unneeded, I'll remove it in the next version that I'll post as soon as possible with the other required amendments. >> /usr/sbin/cpufreqd -- gen_context(system_u:object_r:cpuspeed_exec_t,s0) >> /usr/sbin/cpuspeed -- gen_context(system_u:object_r:cpuspeed_exec_t,s0) >> diff -pruN refpolicy-08082012/policy/modules/contrib/cpucontrol.te >> refpolicy-08082012-microcode/policy/modules/contrib/cpucontrol.te >> --- refpolicy-08082012/policy/modules/contrib/cpucontrol.te 2011-09-09 >> 18:29:23.563610858 +0200 >> +++ refpolicy-08082012-microcode/policy/modules/contrib/cpucontrol.te >> 2012-08-09 00:23:07.079532236 +0200 >> @@ -5,10 +5,21 @@ policy_module(cpucontrol, 1.3.0) >> # Declarations >> # >> >> +## >> +##

>> +## Allow cpucontrol to upload new microcode >> +## to the CPU. >> +##

>> +## >> +gen_tunable(cpucontrol_can_upload_cpu_microcode, false) >> + >> type cpucontrol_t; >> type cpucontrol_exec_t; >> init_system_domain(cpucontrol_t, cpucontrol_exec_t) >> >> +type cpucontrol_initrc_exec_t; >> +init_script_file(cpucontrol_initrc_exec_t) >> + >> type cpucontrol_conf_t; >> files_type(cpucontrol_conf_t) >> >> @@ -37,7 +48,6 @@ kernel_read_proc_symlinks(cpucontrol_t) >> kernel_read_kernel_sysctls(cpucontrol_t) >> >> dev_read_sysfs(cpucontrol_t) >> -dev_rw_cpu_microcode(cpucontrol_t) >> >> fs_search_auto_mountpoints(cpucontrol_t) >> >> @@ -54,6 +64,10 @@ logging_send_syslog_msg(cpucontrol_t) >> >> userdom_dontaudit_use_unpriv_user_fds(cpucontrol_t) >> >> +tunable_policy(`cpucontrol_can_upload_cpu_microcode',` >> + dev_write_cpu_microcode(cpucontrol_t) >> +') > > I don't understand why this is conditional, especially since you removed the read permission on /dev/microcode. The point of the app is to load microcode. Conditional because not everyone might want that to happen. For example, one issue might be the licensing one. It shall add more configurability. Best regards, Guido