260 lines
7.6 KiB
C
260 lines
7.6 KiB
C
#include <linux/compiler.h>
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#include <linux/sched/signal.h>
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#include <linux/slab.h>
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#include <linux/task_work.h>
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#include <linux/thread_info.h>
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#include <linux/seccomp.h>
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#include <linux/bpf.h>
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#include <linux/capability.h>
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#include <linux/cred.h>
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#include <linux/dcache.h>
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#include <linux/err.h>
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#include <linux/fs.h>
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#include <linux/init.h>
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#include <linux/init_task.h>
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#include <linux/kallsyms.h>
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#include <linux/kernel.h>
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#include <linux/kprobes.h>
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#include <linux/mm.h>
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#include <linux/mount.h>
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#include <linux/namei.h>
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#include <linux/nsproxy.h>
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#include <linux/path.h>
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#include <linux/printk.h>
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#include <linux/sched.h>
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#include <linux/security.h>
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#include <linux/stddef.h>
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#include <linux/string.h>
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#include <linux/types.h>
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#include <linux/uaccess.h>
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#include <linux/uidgid.h>
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#include <linux/version.h>
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#include <linux/lsm_hooks.h>
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#include <linux/binfmts.h>
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#include <linux/tty.h>
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#ifndef KSU_HAS_PATH_UMOUNT
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#include <linux/syscalls.h> // sys_umount (<4.17) & ksys_umount (4.17+)
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#endif
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#ifdef MODULE
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#include <linux/list.h>
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#include <linux/irqflags.h>
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#include <linux/mm_types.h>
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#include <linux/rcupdate.h>
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#include <linux/vmalloc.h>
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#endif
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#include "allowlist.h"
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#include "setuid_hook.h"
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#include "feature.h"
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#include "klog.h" // IWYU pragma: keep
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#include "ksu.h"
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#include "manager.h"
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#include "selinux/selinux.h"
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#include "seccomp_cache.h"
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#include "supercalls.h"
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#include "syscall_hook_manager.h"
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#include "kernel_umount.h"
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#include "app_profile.h"
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static bool ksu_enhanced_security_enabled = false;
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static int enhanced_security_feature_get(u64 *value)
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{
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*value = ksu_enhanced_security_enabled ? 1 : 0;
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return 0;
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}
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static int enhanced_security_feature_set(u64 value)
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{
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bool enable = value != 0;
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ksu_enhanced_security_enabled = enable;
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pr_info("enhanced_security: set to %d\n", enable);
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return 0;
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}
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static const struct ksu_feature_handler enhanced_security_handler = {
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.feature_id = KSU_FEATURE_ENHANCED_SECURITY,
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.name = "enhanced_security",
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.get_handler = enhanced_security_feature_get,
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.set_handler = enhanced_security_feature_set,
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};
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static inline bool is_allow_su(void)
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{
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if (is_manager()) {
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// we are manager, allow!
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return true;
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}
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return ksu_is_allow_uid_for_current(current_uid().val);
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}
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static inline bool is_unsupported_uid(uid_t uid)
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{
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#define LAST_APPLICATION_UID 19999
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uid_t appid = uid % 100000;
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return appid > LAST_APPLICATION_UID;
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}
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static bool is_appuid(uid_t uid)
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{
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#define PER_USER_RANGE 100000
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#define FIRST_APPLICATION_UID 10000
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#define LAST_APPLICATION_UID 19999
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uid_t appid = uid % PER_USER_RANGE;
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return appid >= FIRST_APPLICATION_UID && appid <= LAST_APPLICATION_UID;
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}
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int ksu_handle_setresuid(uid_t ruid, uid_t euid, uid_t suid)
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{
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uid_t new_uid = ruid;
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uid_t old_uid = current_uid().val;
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pr_info("handle_setuid from %d to %d\n", old_uid, new_uid);
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if (0 != old_uid) {
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// old process is not root, ignore it.
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if (ksu_enhanced_security_enabled) {
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// disallow any non-ksu domain escalation from non-root to root!
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if (unlikely(new_uid) == 0) {
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if (!is_ksu_domain()) {
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pr_warn("find suspicious EoP: %d %s, from %d to %d\n",
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current->pid, current->comm, old_uid, new_uid);
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force_sig(SIGKILL);
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return 0;
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}
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}
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// disallow appuid decrease to any other uid if it is allowed to su
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if (is_appuid(old_uid)) {
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if (new_uid < old_uid && !ksu_is_allow_uid_for_current(old_uid)) {
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pr_warn("find suspicious EoP: %d %s, from %d to %d\n",
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current->pid, current->comm, old_uid, new_uid);
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force_sig(SIGKILL);
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return 0;
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}
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}
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}
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return 0;
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}
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if (new_uid == 2000) {
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ksu_set_task_tracepoint_flag(current);
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}
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if (!is_appuid(new_uid) || is_unsupported_uid(new_uid)) {
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pr_info("handle setuid ignore non application or isolated uid: %d\n", new_uid);
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ksu_clear_task_tracepoint_flag(current);
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return 0;
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}
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// if on private space, see if its possibly the manager
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if (unlikely(new_uid > 100000 && new_uid % 100000 == ksu_get_manager_uid())) {
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ksu_set_manager_uid(new_uid);
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}
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if (unlikely(ksu_get_manager_uid() == new_uid)) {
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pr_info("install fd for manager: %d\n", new_uid);
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ksu_install_fd();
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spin_lock_irq(¤t->sighand->siglock);
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#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 10, 2) // Android backport this feature in 5.10.2
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ksu_seccomp_allow_cache(current->seccomp.filter, __NR_reboot);
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#else
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// we dont have those new fancy things upstream has
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// lets just do original thing where we disable seccomp
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disable_seccomp();
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#endif
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ksu_set_task_tracepoint_flag(current);
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spin_unlock_irq(¤t->sighand->siglock);
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return 0;
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}
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if (unlikely(ksu_is_allow_uid_for_current(new_uid))) {
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if (current->seccomp.mode == SECCOMP_MODE_FILTER &&
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current->seccomp.filter) {
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spin_lock_irq(¤t->sighand->siglock);
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#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 10, 2) // Android backport this feature in 5.10.2
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ksu_seccomp_allow_cache(current->seccomp.filter, __NR_reboot);
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#else
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// we don't have those new fancy things upstream has
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// lets just do original thing where we disable seccomp
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disable_seccomp();
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#endif
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spin_unlock_irq(¤t->sighand->siglock);
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}
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ksu_set_task_tracepoint_flag(current);
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} else {
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ksu_clear_task_tracepoint_flag(current);
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}
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// Handle kernel umount
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ksu_handle_umount(old_uid, new_uid);
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return 0;
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}
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// kernel 4.4 and 4.9
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#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 10, 0) || \
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defined(CONFIG_IS_HW_HISI) || \
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defined(CONFIG_KSU_ALLOWLIST_WORKAROUND)
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static int ksu_key_permission(key_ref_t key_ref, const struct cred *cred,
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unsigned perm)
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{
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if (init_session_keyring != NULL) {
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return 0;
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}
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if (strcmp(current->comm, "init")) {
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// we are only interested in `init` process
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return 0;
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}
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init_session_keyring = cred->session_keyring;
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pr_info("kernel_compat: got init_session_keyring\n");
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return 0;
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}
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#endif
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#ifndef MODULE
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static struct security_hook_list ksu_hooks[] = {
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#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 10, 0) || \
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defined(CONFIG_IS_HW_HISI) || defined(CONFIG_KSU_ALLOWLIST_WORKAROUND)
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LSM_HOOK_INIT(key_permission, ksu_key_permission)
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#endif
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};
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#if LINUX_VERSION_CODE >= KERNEL_VERSION(6, 8, 0)
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const struct lsm_id ksu_lsmid = {
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.name = "ksu",
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.id = 912,
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};
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#endif
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void __init ksu_lsm_hook_init(void)
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{
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#if LINUX_VERSION_CODE >= KERNEL_VERSION(6, 8, 0)
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// https://elixir.bootlin.com/linux/v6.8/source/include/linux/lsm_hooks.h#L120
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security_add_hooks(ksu_hooks, ARRAY_SIZE(ksu_hooks), &ksu_lsmid);
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#elif LINUX_VERSION_CODE >= KERNEL_VERSION(4, 11, 0)
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security_add_hooks(ksu_hooks, ARRAY_SIZE(ksu_hooks), "ksu");
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#else
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// https://elixir.bootlin.com/linux/v4.10.17/source/include/linux/lsm_hooks.h#L1892
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security_add_hooks(ksu_hooks, ARRAY_SIZE(ksu_hooks));
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#endif
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}
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#endif
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void ksu_setuid_hook_init(void)
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{
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ksu_lsm_hook_init();
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ksu_kernel_umount_init();
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if (ksu_register_feature_handler(&enhanced_security_handler)) {
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pr_err("Failed to register enhanced security feature handler\n");
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}
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}
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void ksu_setuid_hook_exit(void)
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{
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pr_info("ksu_core_exit\n");
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ksu_kernel_umount_exit();
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ksu_unregister_feature_handler(KSU_FEATURE_ENHANCED_SECURITY);
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}
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