There is a race in ueventd's coldboot procedure that permits creation
of device block nodes before platform devices are registered. This happens
when the kernel sends events for adding block devices during ueventd's
coldboot /sys walk.
In this case the device node links used to compute the SELinux context
are not known and the node is created under the generic context:
u:object_r:block_device:s0.
A second add event for block device nodes is triggered after the platform
devices are handled by ueventd and the SELinux context is correctly computed
but the mknod call fails because the node already exists. This patch handles
this error case and updates the node's security context.
The race is introduced by the uevent sent from the sdcard device probe
function. The issue appears when this uevent is triggered during ueventd's
coldboot procedure but before the /sys/devices recursive walk reached the
corresponding sdcard platform device path.
The backtrace looks something like:
1. ueventd_main()
2. device_init()
3. coldboot("/sys/devices");
4. do_coldboot()
5. handle_device_fd()
6. handle_device_event()
6.1 handle_block_device_event()
6.2 handle_platform_device_event()
Because handle_device_fd() reads all events from the netlink socket it may
handle the add events for the sdcard partition nodes send occasionally by the
kernel during coldboot /sys walk procedure.
If handle_device_event() continues with handle_block_device_event()
before handle_platform_device_event() registers the sdcard platform device then
handle_block_device_event() will create device nodes without knowing all block
device symlinks (get_block_device_symlinks()):
1. handle_device(path=/dev/block/mmcblk0p3, links = NULL)
2. make_device(path=/dev/block/mmcblk0p3, links = NULL)
3. selabel_lookup_best_match(path=/dev/block/mmcblk0p3, links = NULL)
returns the default context (u:object_r:block_device:s0) for
/dev/block/mmcblk0p3 instead of more specific context like:
u:object_r:boot_block_device:s0
4. setfscreatecon(u:object_r:block_device:s0)
5. mknod(/dev/block/mmcblk0p3)
So the node is create with the wrong context. Afterwards the coldboot /sys walk
continues and make_device() will be called with correct path and links.
But even if the secontext is computed correctly this time it will not be
applied to the device node because mknod() fails.
I see this issue randomly appearing (one time in 10 reboots) on a Minnoboard
Turbot with external sdcard as the boot device.
BUG=28388946
Signed-off-by: Mihai Serban <mihai.serban@intel.com>
(cherry picked from commit 24a3cbfa73)
Change-Id: I2d217f1c8d48553eb4a37457dbf27fff54051cf9
There is a race in ueventd's coldboot procedure that permits creation
of device block nodes before platform devices are registered. This happens
when the kernel sends events for adding block devices during ueventd's
coldboot /sys walk.
In this case the device node links used to compute the SELinux context
are not known and the node is created under the generic context:
u:object_r:block_device:s0.
A second add event for block device nodes is triggered after the platform
devices are handled by ueventd and the SELinux context is correctly computed
but the mknod call fails because the node already exists. This patch handles
this error case and updates the node's security context.
The race is introduced by the uevent sent from the sdcard device probe
function. The issue appears when this uevent is triggered during ueventd's
coldboot procedure but before the /sys/devices recursive walk reached the
corresponding sdcard platform device path.
The backtrace looks something like:
1. ueventd_main()
2. device_init()
3. coldboot("/sys/devices");
4. do_coldboot()
5. handle_device_fd()
6. handle_device_event()
6.1 handle_block_device_event()
6.2 handle_platform_device_event()
Because handle_device_fd() reads all events from the netlink socket it may
handle the add events for the sdcard partition nodes send occasionally by the
kernel during coldboot /sys walk procedure.
If handle_device_event() continues with handle_block_device_event()
before handle_platform_device_event() registers the sdcard platform device then
handle_block_device_event() will create device nodes without knowing all block
device symlinks (get_block_device_symlinks()):
1. handle_device(path=/dev/block/mmcblk0p3, links = NULL)
2. make_device(path=/dev/block/mmcblk0p3, links = NULL)
3. selabel_lookup_best_match(path=/dev/block/mmcblk0p3, links = NULL)
returns the default context (u:object_r:block_device:s0) for
/dev/block/mmcblk0p3 instead of more specific context like:
u:object_r:boot_block_device:s0
4. setfscreatecon(u:object_r:block_device:s0)
5. mknod(/dev/block/mmcblk0p3)
So the node is create with the wrong context. Afterwards the coldboot /sys walk
continues and make_device() will be called with correct path and links.
But even if the secontext is computed correctly this time it will not be
applied to the device node because mknod() fails.
I see this issue randomly appearing (one time in 10 reboots) on a Minnoboard
Turbot with external sdcard as the boot device.
BUG=28388946
Change-Id: I96e239af29d82b753e5d349b3ecefaad09edee87
Signed-off-by: Mihai Serban <mihai.serban@intel.com>
The old way (using triggers) starts defaultcrypto twice because
queue_property_triggers_action retriggers the action.
Bug: 27452459
Change-Id: I48c844836f551673d0dbfed6c33bd8ee1e035f40
am: c7f5af5
* commit 'c7f5af58d98ad989f1c6c865e92152a62b58d6d0':
ueventd: convert to use pwd family of functions
Change-Id: I5deb10d8cdf6c37bba20c6b7f15f283b4d0009ec
am: 1397e7a
* commit '1397e7af4b432d174dbbc7400cca9a00ce34ea5d':
ueventd: convert to use pwd family of functions
Change-Id: I02c1d78835054bd296ce84586410bbcee1760a9c
Switch ueventd to use the grp.h and pwd.h family of
functions for converting strings to uids. This removes the
need for using android_filesystem_config.h.
Change-Id: I25a6f536bb11683d5cd69a0d7b348d25a272dd3b
Bug: 27999086
Signed-off-by: William Roberts <william.c.roberts@intel.com>
Remove android_filesystem_config.h since it was not being used.
Change-Id: I691513d50a3fdb7563a63aee7551137ba983825c
Bug: 27999086
Signed-off-by: William Roberts <william.c.roberts@intel.com>
Start to move users of android_filesystem_config.h to use the
standard grp and pwd interface functions.
Advantages:
* one copy of android_ids in libc, removing it from init objects.
* immediately starts oem_xxx users and groups in rc.
* future will support _named_ oem ids via backend improvements.
Change-Id: Ib1ae1e0cbdcaaf60deb3759681a6030b615c069c
Bug: 27999086
Signed-off-by: William Roberts <william.c.roberts@intel.com>
(cherry pick from commit a98cc9c202)
Try writing a "0" into:
- /sys/class/leds/lcd-backlight/brightness
- /sys/class/backlight/*/brightness
to turn off the backlight during shutdown cleanup.
Bug: 27506425
Change-Id: Ic8a44dc8909b303f24e14f71cfb43292df60efde
Try writing a "0" into:
- /sys/class/leds/lcd-backlight/brightness
- /sys/class/backlight/*/brightness
to turn off the backlight during shutdown cleanup.
Bug: 27506425
Change-Id: Ic8a44dc8909b303f24e14f71cfb43292df60efde
Switch insmod from using init_module to finit_module. From
"man finit_module":
The finit_module() system call is like init_module(), but reads the
module to be loaded from the file descriptor fd. It is useful when the
authenticity of a kernel module can be determined from its location in
the file system; in cases where that is possible, the overhead of
using cryptographically signed modules to determine the authenticity
of a module can be avoided.
finit_module is preferred over init_module because it allows LSMs, such
as SELinux, to perform a permission check on kernel module loads based on
the file from which the module is loaded. This functionality is not yet
implemented in the Linux kernel, but is on the SEAndroid TODO list.
See https://bitbucket.org/seandroid/wiki/wiki/ToDo
Bug: 27824855
Change-Id: Id0ea88cd1930393c8c73ce38e63d5b2eeadf946a
