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>
Since commit:
kernel: core_hook: switch to prepare_creds (c58e102)
get_cred_rcu is no longer needed.
Signed-off-by: rsuntk <90097027+rsuntk@users.noreply.github.com>
Skip directories that does NOT have the same magic as /data/app.
This is to avoid scanning incfs and any other stacked filesystems.
While this is way dumber, it's way cheaper.
no kern_path(), no missable path_put(), no ref handling.
This is a workaround for Ultra-Legacy kernels where upstream's
method fails.
Seems doing 50+ kern_path() calls is a bad meme.
This supercedes `throne_tracker: avoid cross fs access (tiann#2626)`
- upstream 0b6998b474
Signed-off-by: backslashxx <118538522+backslashxx@users.noreply.github.com>
context: this is known by many as `selinux hook`, `4.9 hook`
add is_ksu_transition check which allows ksud execution under nosuid.
it also eases up integration on 3.X kernels that does not have check_nnp_nosuid.
this also adds a `ksu_execveat_hook` check since this transition is NOT needed
anymore once ksud ran.
Usage:
if (check_ksu_transition(old_tsec, new_tsec))
return 0;
on either check_nnp_nosuid or selinux_bprm_set_creds (after execve sid reset)
reference: dfe003c9fd
taken from:
`allow init exec ksud under nosuid`
- 3df9df42a6
- https://github.com/tiann/KernelSU/pull/166#issue-1565872173
Signed-off-by: backslashxx <118538522+backslashxx@users.noreply.github.com>
Signed-off-by: rsuntk <rsuntk@yukiprjkt.my.id>
`ksu handles devpts with selinux lsm hook` - aviraxp
- no, not yet, but yes we can, thats a good idea.
This change tries to do that, so instead of hooking pts_unix98_lookup or
devpts_get_priv, we just watch security_inode_permission, if its devpts,
pass it along to the original handler.
Signed-off-by: backslashxx <118538522+backslashxx@users.noreply.github.com>
Co-authored-by: backslashxx <118538522+backslashxx@users.noreply.github.com>
I am repasting here what I posted on the source code originally:
/*
* turns out path_umount backport is completely unneeded
* we copy the trick used on strncpy_from_unsafe_user / strncpy_from_user_nofault
* https://elixir.bootlin.com/linux/v4.4.302/source/mm/maccess.c#L184
* basically
*
* mm_segment_t old_fs = get_fs(); // remember original fs segment
* set_fs(USER_DS); // or KERNEL_DS *
* do_whatever_in_userspace();
* set_fs(old_fs); // restore fs segment
*
* * kernel -> user, KERNEL_DS, user -> kernel, USER_DS
*
* so yes, we can try to straight up call a syscall from kernel space
*
* NOTE: on newer kernels you can use force_uaccess_begin + force_uaccess_end
* ref: https://elixir.bootlin.com/linux/v5.10.237/source/mm/maccess.c#L250
*
*/
path_umount backport now optional — neat trick, werks, what can I say.
Backports? Nah, we’re good.
Signed-off-by: backslashxx <118538522+backslashxx@users.noreply.github.com>
On plain ARMv8.0 devices (A53,A57,A73), strncpy_from_user_nofault() sometimes
fails to copy `filename_user` string correctly. This breaks su ofc, breaking
some apps like Termux (Play Store ver), ZArchiver and Root Explorer.
This does NOT seem to affect newer ARMv8.2+ CPUs (A75/A76 and newer)
My speculation? ARMv8.0 has weak speculation :)
here we replace `strncpy_from_user_nofault()` with another routine:
- access_ok() to validate the pointer
- strncpy_from_user() to copy and validate string
- manual null-termination just in case, as strncpy_from_user_nofault also does it
- remove that memset, seems useless as it is an strncpy, not strncat
Kind of mimicking _nofault, but yes with this one we allow pagefaults.
Tested on:
- ARMv8.0 A73.a53, A57.a53, A53.a53
- ARMv8.2 A76.a55
Tested-by: iDead XD <rafifirdaus12bb@gmail.com>
Signed-off-by: backslashxx <118538522+backslashxx@users.noreply.github.com>
- We don't know if KPM can run on arm32-bit devices, so to avoid some problems, add a dependency on 64-bit architectures
kernel/throne_tracker: we just uninstalled the manager, stop looking for it
When the manager UID disappears from packages.list, we correctly
invalidate it — good. But, in the very next breath, we start scanning
/data/app hoping to find it again?
Skip the scan — we’ll catch the reinstall next time packages.list updates.
Signed-off-by: backslashxx <118538522+backslashxx@users.noreply.github.com>
Signed-off-by: ShirkNeko <109797057+ShirkNeko@users.noreply.github.com>
disabling this removes the need for LSM_HOOK_INIT, security_add_hooks and such,.
furthermore, this will also allow easier integration on pre-4.1 kernels.
Expose this and make it a configurable option.
Signed-off-by: backslashxx <118538522+backslashxx@users.noreply.github.com>
`thread_pid` is not defined in kernel 4.14 and lower, leading to compilation issue.
To fix this, use `pids[PIDTYPE_PID].pid` for kernel versions 4.14 and lower.
Else use `thread_pid` for kernel versions 4.19 and higher.
Reference: 107717913b/tracee/tracee.bpf.c (L354)
