config SECURITY_SELINUX
bool "NSA SELinux Support"
depends on SECURITY_NETWORK && AUDIT && NET && INET
select NETWORK_SECMARK
default n
help
This selects NSA Security-Enhanced Linux (SELinux).
You will also need a policy configuration and a labeled filesystem.
If you are unsure how to answer this question, answer N.
config SECURITY_SELINUX_BOOTPARAM
bool "NSA SELinux boot parameter"
depends on SECURITY_SELINUX
default n
help
This option adds a kernel parameter 'selinux', which allows SELinux
to be disabled at boot. If this option is selected, SELinux
functionality can be disabled with selinux=0 on the kernel
command line. The purpose of this option is to allow a single
kernel image to be distributed with SELinux built in, but not
necessarily enabled.
If you are unsure how to answer this question, answer N.
config SECURITY_SELINUX_BOOTPARAM_VALUE
int "NSA SELinux boot parameter default value"
depends on SECURITY_SELINUX_BOOTPARAM
range 0 1
default 1
help
This option sets the default value for the kernel parameter
'selinux', which allows SELinux to be disabled at boot. If this
option is set to 0 (zero), the SELinux kernel parameter will
default to 0, disabling SELinux at bootup. If this option is
set to 1 (one), the SELinux kernel parameter will default to 1,
enabling SELinux at bootup.
If you are unsure how to answer this question, answer 1.
config SECURITY_SELINUX_DISABLE
bool "NSA SELinux runtime disable"
depends on SECURITY_SELINUX
default n
help
This option enables writing to a selinuxfs node 'disable', which
allows SELinux to be disabled at runtime prior to the policy load.
SELinux will then remain disabled until the next boot.
This option is similar to the selinux=0 boot parameter, but is to
support runtime disabling of SELinux, e.g. from /sbin/init, for
portability across platforms where boot parameters are difficult
to employ.
If you are unsure how to answer this question, answer N.
config SECURITY_SELINUX_DEVELOP
bool "NSA SELinux Development Support"
depends on SECURITY_SELINUX
default y
help
This enables the development support option of NSA SELinux,
which is useful for experimenting with SELinux and developing
policies. If unsure, say Y. With this option enabled, the
kernel will start in permissive mode (log everything, deny nothing)
unless you specify enforcing=1 on the kernel command line. You
can interactively toggle the kernel between enforcing mode and
permissive mode (if permitted by the policy) via /selinux/enforce.
config SECURITY_SELINUX_AVC_STATS
bool "NSA SELinux AVC Statistics"
depends on SECURITY_SELINUX
default y
help
This option collects access vector cache statistics to
/selinux/avc/cache_stats, which may be monitored via
tools such as avcstat.
config SECURITY_SELINUX_CHECKREQPROT_VALUE
int "NSA SELinux checkreqprot default value"
depends on SECURITY_SELINUX
range 0 1
default 0
help
This option sets the default value for the 'checkreqprot' flag
that determines whether SELinux checks the protection requested
by the application or the protection that will be applied by the
kernel (including any implied execute for read-implies-exec) for
mmap and mprotect calls. If this option is set to 0 (zero),
SELinux will default to checking the protection that will be applied
by the kernel. If this option is set to 1 (one), SELinux will
default to checking the protection requested by the application.
The checkreqprot flag may be changed from the default via the
'checkreqprot=' boot parameter. It may also be changed at runtime
via /selinux/checkreqprot if authorized by policy.
If you are unsure how to answer this question, answer 0.
='1'>1
firmware: fix NULL pointer dereference in __fw_load_abort()
Since commit 5d47ec02c37ea6 ("firmware: Correct handling of
fw_state_wait() return value") fw_load_abort() could be called twice and
lead us to a kernel crash. This happens only when the firmware fallback
mechanism (regular or custom) is used. The fallback mechanism exposes a
sysfs interface for userspace to upload a file and notify the kernel
when the file is loaded and ready, or to cancel an upload by echo'ing -1
into on the loading file:
echo -n "-1" > /sys/$DEVPATH/loading
This will call fw_load_abort(). Some distributions actually have a udev
rule in place to *always* immediately cancel all firmware fallback
mechanism requests (Debian), they have:
$ cat /lib/udev/rules.d/50-firmware.rules
# stub for immediately telling the kernel that userspace firmware loading
# failed; necessary to avoid long timeouts with CONFIG_FW_LOADER_USER_HELPER=y
SUBSYSTEM=="firmware", ACTION=="add", ATTR{loading}="-1
Distributions with this udev rule would run into this crash only if the
fallback mechanism is used. Since most distributions disable by default
using the fallback mechanism (CONFIG_FW_LOADER_USER_HELPER_FALLBACK),
this would typicaly mean only 2 drivers which *require* the fallback
mechanism could typically incur a crash: drivers/firmware/dell_rbu.c and
the drivers/leds/leds-lp55xx-common.c driver. Distributions enabling
CONFIG_FW_LOADER_USER_HELPER_FALLBACK by default are obviously more
exposed to this crash.
The crash happens because after commit 5b029624948d ("firmware: do not
use fw_lock for fw_state protection") and subsequent fix commit
5d47ec02c37ea6 ("firmware: Correct handling of fw_state_wait() return
value") a race can happen between this cancelation and the firmware
fw_state_wait_timeout() being woken up after a state change with which
fw_load_abort() as that calls swake_up(). Upon error
fw_state_wait_timeout() will also again call fw_load_abort() and trigger
a null reference.
At first glance we could just fix this with a !buf check on
fw_load_abort() before accessing buf->fw_st, however there is a logical
issue in having a state machine used for the fallback mechanism and
preventing access from it once we abort as its inside the buf
(buf->fw_st).
The firmware_class.c code is setting the buf to NULL to annotate an
abort has occurred. Replace this mechanism by simply using the state
check instead. All the other code in place already uses similar checks
for aborting as well so no further changes are needed.
An oops can be reproduced with the new fw_fallback.sh fallback mechanism
cancellation test. Either cancelling the fallback mechanism or the
custom fallback mechanism triggers a crash.
mcgrof@piggy ~/linux-next/tools/testing/selftests/firmware
(git::20170111-fw-fixes)$ sudo ./fw_fallback.sh
./fw_fallback.sh: timeout works
./fw_fallback.sh: firmware comparison works
./fw_fallback.sh: fallback mechanism works
[ this then sits here when it is trying the cancellation test ]
Kernel log:
test_firmware: loading 'nope-test-firmware.bin'
misc test_firmware: Direct firmware load for nope-test-firmware.bin failed with error -2
misc test_firmware: Falling back to user helper
BUG: unable to handle kernel NULL pointer dereference at 0000000000000038
IP: _request_firmware+0xa27/0xad0
PGD 0
Oops: 0000 [#1] SMP
Modules linked in: test_firmware(E) ... etc ...
CPU: 1 PID: 1396 Comm: fw_fallback.sh Tainted: G W E 4.10.0-rc3-next-20170111+ #30
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.10.1-0-g8891697-prebuilt.qemu-project.org 04/01/2014
task: ffff9740b27f4340 task.stack: ffffbb15c0bc8000
RIP: 0010:_request_firmware+0xa27/0xad0
RSP: 0018:ffffbb15c0bcbd10 EFLAGS: 00010246
RAX: 00000000fffffffe RBX: ffff9740afe5aa80 RCX: 0000000000000000
RDX: ffff9740b27f4340 RSI: 0000000000000283 RDI: 0000000000000000
RBP: ffffbb15c0bcbd90 R08: ffffbb15c0bcbcd8 R09: 0000000000000000
R10: 0000000894a0d4b1 R11: 000000000000008c R12: ffffffffc0312480
R13: 0000000000000005 R14: ffff9740b1c32400 R15: 00000000000003e8
FS: 00007f8604422700(0000) GS:ffff9740bfc80000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000038 CR3: 000000012164c000 CR4: 00000000000006e0
Call Trace:
request_firmware+0x37/0x50
trigger_request_store+0x79/0xd0 [test_firmware]
dev_attr_store+0x18/0x30
sysfs_kf_write+0x37/0x40
kernfs_fop_write+0x110/0x1a0
__vfs_write+0x37/0x160
? _cond_resched+0x1a/0x50
vfs_write+0xb5/0x1a0
SyS_write+0x55/0xc0
? trace_do_page_fault+0x37/0xd0
entry_SYSCALL_64_fastpath+0x1e/0xad
RIP: 0033:0x7f8603f49620
RSP: 002b:00007fff6287b788 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000055c307b110a0 RCX: 00007f8603f49620
RDX: 0000000000000016 RSI: 000055c3084d8a90 RDI: 0000000000000001
RBP: 0000000000000016 R08: 000000000000c0ff R09: 000055c3084d6336
R10: 000055c307b108b0 R11: 0000000000000246 R12: 000055c307b13c80
R13: 000055c3084d6320 R14: 0000000000000000 R15: 00007fff6287b950
Code: 9f 64 84 e8 9c 61 fe ff b8 f4 ff ff ff e9 6b f9 ff
ff 48 c7 c7 40 6b 8d 84 89 45 a8 e8 43 84 18 00 49 8b be 00 03 00 00 8b
45 a8 <83> 7f 38 02 74 08 e8 6e ec ff ff 8b 45 a8 49 c7 86 00 03 00 00
RIP: _request_firmware+0xa27/0xad0 RSP: ffffbb15c0bcbd10
CR2: 0000000000000038
---[ end trace 6d94ac339c133e6f ]---
Fixes: 5d47ec02c37e ("firmware: Correct handling of fw_state_wait() return value")
Reported-and-Tested-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reported-and-Tested-by: Patrick Bruenn <p.bruenn@beckhoff.com>
Reported-by: Chris Wilson <chris@chris-wilson.co.uk>
CC: <stable@vger.kernel.org> [3.10+]
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>