Narrow the relabelto rules to a more specific type set
for each domain.
Drop mount permissions from the kernel domain since mounting
occurs after switching to the init domain. This was likely
a residual of when all processes were left in the kernel domain
on a recovery boot due to the missing setcon statement in the
recovery init.rc.
Be consistent with unlabeled filesystems (i.e. filesystems
without any matching fs_use or genfs_contexts entry) so
that we can also unmount them.
Add comments to note the reason for various rules.
Change-Id: I269a1744ed7bf8c6be899494c5dc97847e5a994d
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Don't allow writes to /system from unconfined domains.
/system is always mounted read-only, and no process should
ever need to write there.
Allow recovery to write to /system. This is needed to apply OTA
images.
Change-Id: I11aa8bd0c3b7f53ebe83806a0547ab8d5f25f3c9
Writing to the /proc/self/attr files (encapsulated by the libselinux
set*con functions) enables a program to request a specific security
context for various operations instead of the policy-defined defaults.
The security context specified using these calls is checked by an
operation-specific permission, e.g. dyntransition for setcon,
transition for setexeccon, create for setfscreatecon or
setsockcreatecon, but the ability to request a context at all
is controlled by a process permission. Omit these permissions from
domain.te and only add them back where required so that only specific
domains can even request a context other than the default defined by
the policy.
Change-Id: I6a2fb1279318625a80f3ea8e3f0932bdbe6df676
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
We added these rules to the recovery domain when we removed them
from unconfined to ensure that we did not break anything. But we
have seen no uses of these rules by the recovery domain. Tested
wiping userdata and cache from the recovery and performing an
adb sideload of an ota zip file.
Change-Id: I261cb1124130f73e98b87f3e5a31d6d7f521ff11
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
This was originally to limit the ability to relabel files to
particular types given the ability of all domains to relabelfrom
unlabeled files. Since the latter was removed by
Ied84f8b4b1a0896c1b9f7d783b7463ce09d4807b, this no longer serves
any purpose.
Change-Id: Ic41e94437188183f15ed8b3732c6cd5918da3397
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Only allow to domains as required and amend the existing
neverallow on block_device:blk_file to replace the
exemption for unconfineddomain with an explicit whitelist.
The neverallow does not check other device types as specific
ones may need to be writable by device-specific domains.
Change-Id: I0f2f1f565e886ae110a719a08aa3a1e7e9f23e8c
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Remove sys_ptrace and add a neverallow for it.
Remove sys_rawio and mknod, explicitly allow to kernel, init, and recovery,
and add a neverallow for them.
Remove sys_module. It can be added back where appropriate in device
policy if using a modular kernel. No neverallow since it is device
specific.
Change-Id: I1a7971db8d247fd53a8f9392de9e46250e91f89b
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Only allow to specific domains as required, and add a neverallow
to prevent allowing it to other domains not explicitly whitelisted.
sdcard_type is exempted from the neverallow since more domains
require the ability to mount it, including device-specific domains.
Change-Id: Ia6476d1c877f5ead250749fb12bff863be5e9f27
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Linux defines two capabilities for Mandatory Access Control (MAC)
security modules, CAP_MAC_OVERRIDE (override MAC access restrictions)
and CAP_MAC_ADMIN (allow MAC configuration or state changes).
SELinux predates these capabilities and did not originally use them,
but later made use of CAP_MAC_ADMIN as a way to control the ability
to set security context values unknown to the currently loaded
SELinux policy on files. That facility is used in Linux for e.g.
livecd creation where a file security context that is being set
on a generated filesystem is not known to the build host policy.
Internally, files with such labels are treated as having the unlabeled
security context for permission checking purposes until/unless the
context is later defined through a policy reload.
CAP_MAC_OVERRIDE is never checked by SELinux, so it never needs
to be allowed. CAP_MAC_ADMIN is only checked if setting an
unknown security context value; the only legitimate use I can see
in Android is the recovery console, where a context may need to be set
on /system that is not defined in the recovery policy.
Remove these capabilities from unconfined domains, allow
mac_admin for the recovery domain, and add neverallow rules.
Change-Id: Ief673e12bc3caf695f3fb67cabe63e68f5f58150
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Requires execmem and ashmem_device:chr_file execute similar to bootanim
presumably for the display.
Did not see any cache_file execute denials and do not see any
exec of /cache files in the code, only reading/interpreting scripts,
so I removed cache_file rx_file_perms.
Did not see any tmpfs execute denials in /proc/last_kmsg but the
source code appears to extract the update-binary to a tmpfs mount
in /tmp and then exec it. So I retained that rule.
Tested with adb sideload.
Change-Id: I8ca5f2cd390be1adf063f16e6280cc4cd1833c0e
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Define a domain for use by the recovery init.rc file for
/sbin/recovery. Start with a copy of the kernel domain
rules since that is what /sbin/recovery was previously running in,
and then add rules as appropriate.
Change-Id: Ie3d86547d5be0b68dd1875a97afe1e00fc3e4da1
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
