* Following the advice that was given by member in rksu group, by replacing ALL to untrusted_app.
$ /system/bin/stat /proc/1
Result:
08-15 14:57:54.370 20062 20062 W stat : type=1400 audit(0.0:9564): avc: denied { getattr } for path="/proc/1" dev="proc" ino=12308 scontext=u:r:untrusted_app_27:s0:c27,c258,c512,c768 tcontext=u:r:init:s0 tclass=dir permissive=0 app=com.termux
(issue
438bd5fd6d (commitcomment-163785768))
Test: Checker pass.
* Any issue? Let me know.
Tested-by: rsuntk <rsuntk@yukiprjkt.my.id>
Signed-off-by: rsuntk <rsuntk@yukiprjkt.my.id>
* Maybe there's much better solution than this.
This reverts commit 438bd5fd6dac74ba63ef627124f0d2f552b1cb31.
Signed-off-by: rsuntk <rsuntk@yukiprjkt.my.id>
* Much cleaner code, although setenforce is not used anymore
* Guard is_ksu_transition only for 4.19 and under.
Signed-off-by: rsuntk <rsuntk@yukiprjkt.my.id>
Tracepoint is a predefined hook point in the kernel, compared to Kprobe,
it is more stable and has lower performance overhead, although compatibility
is relatively poor, it is still worth trying
By the way, we have also included the config definitions related to hook types
in Kconfig, to enhance cleanliness
Improve and merge types that do not require hooks
Introducing the hook type prctl
These patches is based on backslashxx/KernelSU#5
Co-authored-by: Cloud_Yun <1770669041@qq.com>
Co-authored-by: Prslc <prslc113@gmail.com>
Co-authored-by: ShirkNeko <109797057+ShirkNeko@users.noreply.github.com>
Signed-off-by: ShirkNeko <109797057+ShirkNeko@users.noreply.github.com>
Isolated processes can be directly forked from zygote, but current code doesn't handle it well. Fix it by unmounting unconditionally if isolated process is forked from zygote.
Signed-off-by: rsuntk <rsuntk@yukiprjkt.my.id>
get_policydb() uses rcu_dereference() to read pointers to selinux_state.policy.
But in the SELinux implementation, these pointers are assigned once during
initialization and never changed with rcu_assign_pointer(), rendering the
rcu_dereference() call in get_policydb() completely useless. This just adds
unwanted overhead and implies concurrency pattern that is not even present in
the kernel.
Therefore, read the pointers directly since it's safe.
* selinux_state.ss needs more context.
Signed-off-by: Tashfin Shakeer Rhythm <tashfinshakeerrhythm@gmail.com>
Currently, handle_sepolicy() holds an RCU read lock across the entire
function including calls to strncpy_from_user() which can sleep, which
is illegal in RCU semantics.
This triggers the following warning when the kernel is compiled with
CONFIG_DEBUG_ATOMIC_SLEEP enabled:
[ 8.526345] BUG: sleeping function called from invalid context at lib/strncpy_from_user.c:40
[ 8.526349] in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid: 683, name: ksud
[ 8.526351] preempt_count: 0, expected: 0
[ 8.526352] RCU nest depth: 1, expected: 0
[ 8.526354] 1 lock held by ksud/683:
[ 8.526355] #0: ffffffe013e1b970 (rcu_read_lock){....}, at: handle_sepolicy+0xe4/0xaa0
[ 8.526365] CPU: 6 PID: 683 Comm: ksud Tainted: G W 5.4.289-Scarlet-v2.2-beta2 #1
[ 8.526366] Hardware name: redwood based Qualcomm Technologies, Inc. SM7325 (DT)
[ 8.526367] Call trace:
[ 8.526371] dump_backtrace+0x0/0x1c0
[ 8.526374] dump_stack+0x90/0xcc
[ 8.526376] __might_sleep+0x1a0/0x200
[ 8.526378] __might_fault+0x28/0x40
[ 8.526381] strncpy_from_user+0xac/0x300
[ 8.526383] handle_sepolicy+0x588/0xaa0
[ 8.526385] ksu_handle_prctl+0x368/0xd60
[ 8.526386] ksu_task_prctl+0xc/0x20
[ 8.526389] security_task_prctl+0x5c/0xa0
[ 8.526391] __arm64_sys_prctl+0x58/0x7e0
[ 8.526393] do_el0_svc+0x68/0x120
[ 8.526394] el0_sync_handler+0x11c/0x1c0
[ 8.526395] el0_sync+0x140/0x180
To fix this, replace the rcu_read_lock() with the `ksu_rules` mutex_lock()
introduced with commit 9014c663d1eb4 ("kernel: selinux: rules: Fix illegal RCU
lock usage in apply_kernelsu_rules()") which allows sleeping.
This mutex_lock() ensures mutual exclusion between threads invoking dynamic
policy modifications via handle_sepolicy() and those applying KernelSU rules
via apply_kernelsu_rules(), both of which access the policydb structure through
get_policydb().
Signed-off-by: Tashfin Shakeer Rhythm <tashfinshakeerrhythm@gmail.com>
* We got a splat related to atomic sleep.
* The trace is from strncpy_from_user and might_fault
Same case:
e47115e009
Signed-off-by: rsuntk <rsuntk@yukiprjkt.my.id>
When kernel is compiled with CONFIG_DEBUG_ATOMIC_SLEEP enabled, it prints
the following splat in dmesg during post boot:
[ 6.739169] init: Opening SELinux policy
[ 6.751520] init: Loading SELinux policy
[ 6.894684] SELinux: policy capability network_peer_controls=1
[ 6.894688] SELinux: policy capability open_perms=1
[ 6.894690] SELinux: policy capability extended_socket_class=1
[ 6.894691] SELinux: policy capability always_check_network=0
[ 6.894693] SELinux: policy capability cgroup_seclabel=0
[ 6.894695] SELinux: policy capability nnp_nosuid_transition=1
[ 7.214323] selinux: SELinux: Loaded file context from:
[ 7.214332] selinux: /system/etc/selinux/plat_file_contexts
[ 7.214339] selinux: /system_ext/etc/selinux/system_ext_file_contexts
[ 7.214345] selinux: /product/etc/selinux/product_file_contexts
[ 7.214350] selinux: /vendor/etc/selinux/vendor_file_contexts
[ 7.214356] selinux: /odm/etc/selinux/odm_file_contexts
[ 7.216398] KernelSU: /system/bin/init argc: 2
[ 7.216401] KernelSU: /system/bin/init first arg: second_stage
[ 7.216403] KernelSU: /system/bin/init second_stage executed
[ 7.216506] BUG: sleeping function called from invalid context at security/selinux/ss/hashtab.c:47
[ 7.216512] in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid: 1, name: init
[ 7.216516] preempt_count: 0, expected: 0
[ 7.216518] RCU nest depth: 1, expected: 0
[ 7.216524] CPU: 6 PID: 1 Comm: init Not tainted 5.4.289-Scarlet-v2.0-beta3 #1
[ 7.216526] Hardware name: redwood based Qualcomm Technologies, Inc. SM7325 (DT)
[ 7.216528] Call trace:
[ 7.216536] dump_backtrace+0x0/0x210
[ 7.216539] show_stack+0x14/0x20
[ 7.216544] dump_stack+0x9c/0xec
[ 7.216548] __might_resched+0x1f0/0x210
[ 7.216552] hashtab_insert+0x38/0x230
[ 7.216557] add_type+0xd4/0x2e0
[ 7.216559] ksu_type+0x24/0x60
[ 7.216562] apply_kernelsu_rules+0xa8/0x650
[ 7.216565] ksu_handle_execveat_ksud+0x2a8/0x460
[ 7.216568] ksu_handle_execveat+0x2c/0x60
[ 7.216571] __arm64_sys_execve+0xe8/0xf0
[ 7.216574] el0_svc_common+0xf4/0x1a0
[ 7.216577] do_el0_svc+0x2c/0x40
[ 7.216579] el0_sync_handler+0x18c/0x200
[ 7.216582] el0_sync+0x140/0x180
This is because apply_kernelsu_rules() uses rcu_read_lock() to protect
SELinux policy modifications. However, cond_resched() from
hashtab_insert() at security/selinux/ss/hashtab.c is internally called
and it sleeps which is illegal under an RCU read-side critical section.
While replacing it with a spinlock would suppress the warning, this is
fundamentally incorrect because sleeping is illegal while holding a
spinlock and spinlock would turn off preemption which isn't an ideal
solution since it intentionally turns off rescheduling, and can lead
to deadlocks.
Instead, replace the RCU lock with a mutex lock. Mutex lock allows
sleeping when necessary, which is appropriate here because
apply_kernelsu_rules() runs in process context, not in atomic or
interrupt context. As apply_kernelsu_rules() is invoked only once during
post boot (SYSTEM_RUNNING), the mutex lock does not introduce any major
runtime performance regression and provides correct synchronization.
Fixes: tiann#2637
Signed-off-by: Tashfin Shakeer Rhythm <tashfinshakeerrhythm@gmail.com>
* Since it's interceptable from LSM Hook,
then we just need to remove ksu_handle_devpts and
make a decoy for it.
Signed-off-by: rsuntk <rsuntk@yukiprjkt.my.id>
Use strscpy()/strlcpy() to populate the version buffer in CMD_GET_FULL_VERSION
instead of relying on uninitialized memory. This ensures the returned string
is null-terminated and avoids exposing garbage data to user space.
Signed-off-by: schqiushui <orochi9999@gmail.com>
