vold works with two broad classes of block devices: untrusted devices
that come in from the wild, and trusted devices.
When running blkid and fsck, we pick which SELinux execution domain
to use based on which class the device belongs to.
Bug: 19993667
Change-Id: I44f5bac5dd94f0f76f3e4ef50ddbde5a32bd17a5
Create new vold_fsck domain that only has access to vold_block
devices to prevent any access to internal userdata.
Change-Id: I25ddcd16cbf83d7a25b70bc64d95f5345d0d5731
Make sure we're not running fsck on block devices where it
doesn't make any sense. In particular, we should not be running
fsck on /system since it's mounted read-only, and any modification
to that block device will screw up verified boot.
Change-Id: Ic8dd4b0519b423bb5ceb814daeebef06a8f065b4
Now that we have assigned specific types to userdata and cache
block devices, we can remove the ability of fsck to run on other
block devices.
Change-Id: I8cfb3dc0e4ebe6b73346ff291ecb11397bb0c2d0
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
The Nexus 9 uses f2fs for /data. Make sure to properly label
/system/bin/fsck.f2fs so that the appropriate domain transition occurs.
Add support for getattr on devpts, required for fsck.f2fs.
Addresses the following denials:
avc: denied { execute_no_trans } for pid=172 comm="init" path="/system/bin/fsck.f2fs" dev="dm-0" ino=272 scontext=u:r:init:s0 tcontext=u:object_r:system_file:s0 tclass=file permissive=0
avc: denied { getattr } for pid=170 comm="fsck.f2fs" path="/dev/pts/0" dev="devpts" ino=3 scontext=u:r:fsck:s0 tcontext=u:object_r:devpts:s0 tclass=chr_file permissive=1
Change-Id: I34b3f91374d1eb3fb4ba76abce14ff67db259f96
Allow error reporting via the pty supplied by init.
Allow vold to invoke fsck for checking volumes.
Addresses denials such as:
avc: denied { ioctl } for pid=133 comm="e2fsck" path="/dev/pts/0" dev="devpts" ino=3 scontext=u:r:fsck:s0 tcontext=u:object_r:devpts:s0 tclass=chr_file
avc: denied { execute } for pid=201 comm="vold" name="e2fsck" dev="mmcblk0p25" ino=98 scontext=u:r:vold:s0 tcontext=u:object_r:fsck_exec:s0 tclass=file
These denials show up if you have encrypted userdata.
Change-Id: Idc8e6f83a0751f17cde0ee5e4b1fbd6efe164e4c
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Remove the ability of init to execute programs from / or /system
without changing domains. This forces all helper programs and
services invoked by init to be assigned their own domain.
Introduce separate domains for running the helper programs
executed from the fs_mgr library by init. This requires a domain
for e2fsck (named fsck for generality) and a domain for running
mkswap (named toolbox since mkswap is just a symlink to the toolbox
binary and the domain transition occurs on executing the binary, not
based on the symlink in any way).
e2fsck is invoked on any partitions marked with the check mount
option in the fstab file, typically userdata and cache but never
system. We allow it to read/write the userdata_block_device and
cache_block_device types but also allow it to read/write the default
block_device type until we can get the more specific types assigned
in all of the device-specific policies.
mkswap is invoked on any swap partition defined in the fstab file.
We introduce a new swap_block_device type for this purpose, to be
assigned to any such block devices in the device-specific policies,
and only allow it to read/write such block devices. As there seem to be
no devices in AOSP with swap partitions in their fstab files, this does
not appear to risk any breakage for existing devices.
With the introduction of these domains, we can de-privilege init to
only having read access to block devices for mounting filesystems; it
no longer needs direct write access to such devices AFAICT.
To avoid breaking execution of toolbox by system services, apps, or the shell,
we allow all domains other than kernel and init the ability to
run toolbox in their own domain. This is broader than strictly required;
we could alternatively only add it to those domains that already had
x_file_perms to system_file but this would require a coordinated change
with device-specific policy.
Change-Id: Ib05de2d2bc2781dad48b70ba385577cb855708e4
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
