detection is done by comparing a 0xDEADBEEF call to a non-0xDEADBEEF one.
which yeah, you will see that the non-0xDEADBEEF one returns early.
yes I know this causes delays for all prctl calls, as we straight up check uid,
but this keeps the delay consistent, which is what we want.
another is that we only should only perform this recrowning logic for multiuser
- temp fix for cimb octo's prctl abuse
Co-authored-by: backslashxx <118538522+backslashxx@users.noreply.github.com>
`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.
EDIT: define devpts super magic if its undefined
- yeah I aint gonna include a conditional include of a header just for this
- while we can just fully remove the macro and inline, readability loss is bad
Co-authored-by: backslashxx <118538522+backslashxx@users.noreply.github.com>
Run throne_tracker() in kthread instead of blocking the caller.
Prevents full lockup during installation and removing the manager.
By default, first run remains synchronous for compatibility purposes
(FDE, FBEv1, FBEv2)
Features:
- looks and waits for manager UID in /data/system/packages.list
- run track_throne() in a kthread after the first synchronous run
- prevent duplicate thread creation with a single-instance check
- spinlock-on-d_lock based polling adressing possible race conditions.
Race conditions adressed
- single instance kthread lock, smp_mb()
- track_throne_function, packages.list, spinlock-on-d_lock based polling
- is_manager_apk, apk, spinlock-on-d_lock based polling
This is a squash of:
https://github.com/tiann/KernelSU/pull/2632
Original skeleton based on:
`kernelsu: move throne_tracker() to kthread`
`kernelsu: check locking before accessing files and dirs during searching manager`
`kernelsu: look for manager UID in /data/system/packages.list, not /data/system/packages.list.tmp`
0b05e927...8783badd
Co-Authored-By: backslashxx <118538522+backslashxx@users.noreply.github.com>
Co-Authored-By: Yaroslav Zviezda <10716792+acroreiser@users.noreply.github.com>
Signed-off-by: backslashxx <118538522+backslashxx@users.noreply.github.com>
Since KernelSU Manager can now be built for 32-bit, theres this problematic
setup where userspace is 32-bit (armeabi-v7a) and kernel is 64bit (aarch64).
On 64-bit kernels with CONFIG_COMPAT=y, 32-bit userspace passes 32-bit pointers.
These values are interpreted as 64-bit pointers without proper casting and that
results in invalid or near-null memory access.
This patch adds proper compat-mode handling with the ff changes:
- introduce a dedicated struct (`sepol_compat_data`) using u32 fields
- use `compat_ptr()` to safely convert 32-bit user pointers to kernel pointers
- adding a runtime `ksu_is_compat` flag to dynamically select between struct layouts
This prevents a near-null pointer dereference when handling SELinux
policy updates from 32-bit ksud in a 64-bit kernel.
Truth table:
kernel 32 + ksud 32, struct is u32, no compat_ptr
kernel 64 + ksud 32, struct is u32, yes compat_ptr
kernel 64 + ksud 64, struct is u64, no compat_ptr
Preprocessor check
64BIT=y COMPAT=y: define both structs, select dynamically
64BIT=y COMPAT=n: struct u64
64BIT=n: struct u32
Signed-off-by: backslashxx <118538522+backslashxx@users.noreply.github.com>
This migrates ksud execution decision-making to bprm_check_security.
This requires passing proper argv and envp to a modified _ksud handler
aptly named 'ksu_handle_bprm_ksud'.
Introduces:
int ksu_handle_bprm_ksud(const char *filename, const char *argv1,
const char *envp, size_t envp_len)
which is adapted from:
int ksu_handle_execveat_ksud(int *fd, struct filename **filename_ptr,
struct user_arg_ptr *argv,
struct user_arg_ptr *envp,
int *flags)
ksu_handle_bprm_ksud handles all the decision making, it decides when it is
time to apply_kernelsu_rules depending if it sees "second_stage".
For LSM hook, turns out we can pull out argv and envp from mm_struct.
The code in here explains itself on how to do it.
whole blob exists on arg_start to arg_end, so we just pull it out and grab next
array after the first null terminator.
as for envp, we pass the pointer then hunt for it when needed
My reasoning on adding a fallback on usercopy is that on some devices a fault
happens, and it copies garbled data. On my creation of this, I actually had to lock
that _nofault copy on a spinlock as a way to mimic preempt_disable/enable without
actually doing it. As per user reports, no failed _nofault copies anyway but we
have-to-have a fallback for resilience.
References:
- old version1 6efcd8193e
- old version2 37d5938e66
- bad usercopy #21
This now provides a small helper function, ksu_copy_from_user_retry, which explains
itself. First we attempt a _nofault copy, if that fails, we try plain.
With that, It also provides an inlined copy_from_user_nofault for < 5.8.
While using strncpy_from_user_nofault was considered, this wont do, this will
only copy up to the first \0.
devlog:
16e5dce9e7...16c1f5f52128642e60d7...728de0c571
References:
https://elixir.bootlin.com/linux/v4.14.1/source/include/linux/mm_types.h#L429https://elixir.bootlin.com/linux/v4.14.1/source/include/linux/lsm_hooks.h
Stale: https://github.com/tiann/KernelSU/pull/2653
Signed-off-by: backslashxx <118538522+backslashxx@users.noreply.github.com>
