#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "allowlist.h" #include "arch.h" #include "core_hook.h" #include "feature.h" #include "klog.h" // IWYU pragma: keep #include "ksu.h" #include "ksud.h" #include "manager.h" #include "selinux/selinux.h" #include "kernel_compat.h" #include "supercalls.h" #include "sucompat.h" #include "sulog.h" #include "throne_tracker.h" #include "throne_comm.h" #include "umount_manager.h" #ifdef CONFIG_KSU_MANUAL_SU #include "manual_su.h" #endif bool ksu_module_mounted __read_mostly = false; #ifdef CONFIG_COMPAT bool ksu_is_compat __read_mostly = false; #endif #ifndef DEVPTS_SUPER_MAGIC #define DEVPTS_SUPER_MAGIC 0x1cd1 #endif extern int __ksu_handle_devpts(struct inode *inode); // sucompat.c #ifdef CONFIG_KSU_MANUAL_SU static void ksu_try_escalate_for_uid(uid_t uid) { if (!is_pending_root(uid)) return; pr_info("pending_root: UID=%d temporarily allowed\n", uid); remove_pending_root(uid); } #endif static bool ksu_kernel_umount_enabled = true; static bool ksu_enhanced_security_enabled = false; static int kernel_umount_feature_get(u64 *value) { *value = ksu_kernel_umount_enabled ? 1 : 0; return 0; } static int kernel_umount_feature_set(u64 value) { bool enable = value != 0; ksu_kernel_umount_enabled = enable; pr_info("kernel_umount: set to %d\n", enable); return 0; } static const struct ksu_feature_handler kernel_umount_handler = { .feature_id = KSU_FEATURE_KERNEL_UMOUNT, .name = "kernel_umount", .get_handler = kernel_umount_feature_get, .set_handler = kernel_umount_feature_set, }; static int enhanced_security_feature_get(u64 *value) { *value = ksu_enhanced_security_enabled ? 1 : 0; return 0; } static int enhanced_security_feature_set(u64 value) { bool enable = value != 0; ksu_enhanced_security_enabled = enable; pr_info("enhanced_security: set to %d\n", enable); return 0; } static const struct ksu_feature_handler enhanced_security_handler = { .feature_id = KSU_FEATURE_ENHANCED_SECURITY, .name = "enhanced_security", .get_handler = enhanced_security_feature_get, .set_handler = enhanced_security_feature_set, }; static inline bool is_allow_su() { if (is_manager()) { // we are manager, allow! return true; } return ksu_is_allow_uid_for_current(current_uid().val); } static inline bool is_unsupported_uid(uid_t uid) { #define LAST_APPLICATION_UID 19999 uid_t appid = uid % 100000; return appid > LAST_APPLICATION_UID; } #if LINUX_VERSION_CODE >= KERNEL_VERSION (6, 7, 0) static struct group_info root_groups = { .usage = REFCOUNT_INIT(2), }; #else static struct group_info root_groups = { .usage = ATOMIC_INIT(2) }; #endif static void setup_groups(struct root_profile *profile, struct cred *cred) { if (profile->groups_count > KSU_MAX_GROUPS) { pr_warn("Failed to setgroups, too large group: %d!\n", profile->uid); return; } if (profile->groups_count == 1 && profile->groups[0] == 0) { // setgroup to root and return early. if (cred->group_info) put_group_info(cred->group_info); cred->group_info = get_group_info(&root_groups); return; } u32 ngroups = profile->groups_count; struct group_info *group_info = groups_alloc(ngroups); if (!group_info) { pr_warn("Failed to setgroups, ENOMEM for: %d\n", profile->uid); return; } int i; for (i = 0; i < ngroups; i++) { gid_t gid = profile->groups[i]; kgid_t kgid = make_kgid(current_user_ns(), gid); if (!gid_valid(kgid)) { pr_warn("Failed to setgroups, invalid gid: %d\n", gid); put_group_info(group_info); return; } group_info->gid[i] = kgid; } groups_sort(group_info); set_groups(cred, group_info); put_group_info(group_info); } static void disable_seccomp() { assert_spin_locked(¤t->sighand->siglock); // disable seccomp #if defined(CONFIG_GENERIC_ENTRY) && \ LINUX_VERSION_CODE >= KERNEL_VERSION(5, 11, 0) clear_syscall_work(SECCOMP); #else clear_thread_flag(TIF_SECCOMP); #endif #ifdef CONFIG_SECCOMP current->seccomp.mode = 0; current->seccomp.filter = NULL; #else #endif } void escape_to_root(void) { struct cred *cred; struct task_struct *p = current; struct task_struct *t; cred = prepare_creds(); if (!cred) { pr_warn("prepare_creds failed!\n"); return; } if (cred->euid.val == 0) { pr_warn("Already root, don't escape!\n"); #if __SULOG_GATE ksu_sulog_report_su_grant(current_euid().val, NULL, "escape_to_root_failed"); #endif abort_creds(cred); return; } struct root_profile *profile = ksu_get_root_profile(cred->uid.val); cred->uid.val = profile->uid; cred->suid.val = profile->uid; cred->euid.val = profile->uid; cred->fsuid.val = profile->uid; cred->gid.val = profile->gid; cred->fsgid.val = profile->gid; cred->sgid.val = profile->gid; cred->egid.val = profile->gid; cred->securebits = 0; BUILD_BUG_ON(sizeof(profile->capabilities.effective) != sizeof(kernel_cap_t)); // setup capabilities // we need CAP_DAC_READ_SEARCH becuase `/data/adb/ksud` is not accessible for non root process // we add it here but don't add it to cap_inhertiable, it would be dropped automaticly after exec! u64 cap_for_ksud = profile->capabilities.effective | CAP_DAC_READ_SEARCH; memcpy(&cred->cap_effective, &cap_for_ksud, sizeof(cred->cap_effective)); memcpy(&cred->cap_permitted, &profile->capabilities.effective, sizeof(cred->cap_permitted)); memcpy(&cred->cap_bset, &profile->capabilities.effective, sizeof(cred->cap_bset)); setup_groups(profile, cred); commit_creds(cred); // Refer to kernel/seccomp.c: seccomp_set_mode_strict // When disabling Seccomp, ensure that current->sighand->siglock is held during the operation. spin_lock_irq(¤t->sighand->siglock); disable_seccomp(); spin_unlock_irq(¤t->sighand->siglock); setup_selinux(profile->selinux_domain); #if __SULOG_GATE ksu_sulog_report_su_grant(current_euid().val, NULL, "escape_to_root"); #endif for_each_thread (p, t) { ksu_set_task_tracepoint_flag(t); } } #ifdef CONFIG_KSU_MANUAL_SU static void disable_seccomp_for_task(struct task_struct *tsk) { if (!tsk->seccomp.filter && tsk->seccomp.mode == SECCOMP_MODE_DISABLED) return; if (WARN_ON(!spin_is_locked(&tsk->sighand->siglock))) return; #ifdef CONFIG_SECCOMP tsk->seccomp.mode = 0; if (tsk->seccomp.filter) { #if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 10, 0) seccomp_filter_release(tsk); atomic_set(&tsk->seccomp.filter_count, 0); #else // for 6.11+ kernel support? #if LINUX_VERSION_CODE < KERNEL_VERSION(5, 9, 0) put_seccomp_filter(tsk); #endif tsk->seccomp.filter = NULL; #endif } #endif } void escape_to_root_for_cmd_su(uid_t target_uid, pid_t target_pid) { struct cred *newcreds; struct task_struct *target_task; struct task_struct *p = current; struct task_struct *t; pr_info("cmd_su: escape_to_root_for_cmd_su called for UID: %d, PID: %d\n", target_uid, target_pid); // Find target task by PID rcu_read_lock(); target_task = pid_task(find_vpid(target_pid), PIDTYPE_PID); if (!target_task) { rcu_read_unlock(); pr_err("cmd_su: target task not found for PID: %d\n", target_pid); #if __SULOG_GATE ksu_sulog_report_su_grant(target_uid, "cmd_su", "target_not_found"); #endif return; } get_task_struct(target_task); rcu_read_unlock(); if (task_uid(target_task).val == 0) { pr_warn("cmd_su: target task is already root, PID: %d\n", target_pid); put_task_struct(target_task); return; } newcreds = prepare_kernel_cred(target_task); if (newcreds == NULL) { pr_err("cmd_su: failed to allocate new cred for PID: %d\n", target_pid); #if __SULOG_GATE ksu_sulog_report_su_grant(target_uid, "cmd_su", "cred_alloc_failed"); #endif put_task_struct(target_task); return; } struct root_profile *profile = ksu_get_root_profile(target_uid); newcreds->uid.val = profile->uid; newcreds->suid.val = profile->uid; newcreds->euid.val = profile->uid; newcreds->fsuid.val = profile->uid; newcreds->gid.val = profile->gid; newcreds->fsgid.val = profile->gid; newcreds->sgid.val = profile->gid; newcreds->egid.val = profile->gid; newcreds->securebits = 0; u64 cap_for_cmd_su = profile->capabilities.effective | CAP_DAC_READ_SEARCH | CAP_SETUID | CAP_SETGID; memcpy(&newcreds->cap_effective, &cap_for_cmd_su, sizeof(newcreds->cap_effective)); memcpy(&newcreds->cap_permitted, &profile->capabilities.effective, sizeof(newcreds->cap_permitted)); memcpy(&newcreds->cap_bset, &profile->capabilities.effective, sizeof(newcreds->cap_bset)); setup_groups(profile, newcreds); task_lock(target_task); const struct cred *old_creds = get_task_cred(target_task); rcu_assign_pointer(target_task->real_cred, newcreds); rcu_assign_pointer(target_task->cred, get_cred(newcreds)); task_unlock(target_task); if (target_task->sighand) { spin_lock_irq(&target_task->sighand->siglock); disable_seccomp_for_task(target_task); spin_unlock_irq(&target_task->sighand->siglock); } setup_selinux(profile->selinux_domain); put_cred(old_creds); wake_up_process(target_task); if (target_task->signal->tty) { struct inode *inode = target_task->signal->tty->driver_data; if (inode && inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC) { __ksu_handle_devpts(inode); } } put_task_struct(target_task); #if __SULOG_GATE ksu_sulog_report_su_grant(target_uid, "cmd_su", "manual_escalation"); #endif for_each_thread (p, t) { ksu_set_task_tracepoint_flag(t); } pr_info("cmd_su: privilege escalation completed for UID: %d, PID: %d\n", target_uid, target_pid); } #endif #ifdef CONFIG_EXT4_FS extern void ext4_unregister_sysfs(struct super_block *sb); void nuke_ext4_sysfs(void) { struct path path; int err = kern_path("/data/adb/modules", 0, &path); if (err) { pr_err("nuke path err: %d\n", err); return; } struct super_block *sb = path.dentry->d_inode->i_sb; const char *name = sb->s_type->name; if (strcmp(name, "ext4") != 0) { pr_info("nuke but module aren't mounted\n"); return; } ext4_unregister_sysfs(sb); path_put(&path); } #else inline void nuke_ext4_sysfs(void) { } #endif bool is_system_uid(void) { if (!current->mm || current->in_execve) { return 0; } uid_t caller_uid = current_uid().val; return caller_uid <= 2000; } static bool is_appuid(kuid_t uid) { #define PER_USER_RANGE 100000 #define FIRST_APPLICATION_UID 10000 #define LAST_APPLICATION_UID 19999 uid_t appid = uid.val % PER_USER_RANGE; return appid >= FIRST_APPLICATION_UID && appid <= LAST_APPLICATION_UID; } static bool should_umount(struct path *path) { if (!path) { return false; } if (current->nsproxy->mnt_ns == init_nsproxy.mnt_ns) { pr_info("ignore global mnt namespace process: %d\n", current_uid().val); return false; } if (path->mnt && path->mnt->mnt_sb && path->mnt->mnt_sb->s_type) { const char *fstype = path->mnt->mnt_sb->s_type->name; return strcmp(fstype, "overlay") == 0; } return false; } extern int path_umount(struct path *path, int flags); static void ksu_umount_mnt(struct path *path, int flags) { int err = path_umount(path, flags); if (err) { pr_info("umount %s failed: %d\n", path->dentry->d_iname, err); } } static void try_umount(const char *mnt, bool check_mnt, int flags) { struct path path; int err = kern_path(mnt, 0, &path); if (err) { return; } if (path.dentry != path.mnt->mnt_root) { // it is not root mountpoint, maybe umounted by others already. path_put(&path); return; } // we are only interest in some specific mounts if (check_mnt && !should_umount(&path)) { path_put(&path); return; } ksu_umount_mnt(&path, flags); } struct umount_tw { struct callback_head cb; const struct cred *old_cred; }; static void umount_tw_func(struct callback_head *cb) { struct umount_tw *tw = container_of(cb, struct umount_tw, cb); const struct cred *saved = NULL; if (tw->old_cred) { saved = override_creds(tw->old_cred); } ksu_umount_manager_execute_all(tw->old_cred); if (saved) revert_creds(saved); if (tw->old_cred) put_cred(tw->old_cred); kfree(tw); } int ksu_handle_setuid(struct cred *new, const struct cred *old) { struct umount_tw *tw; if (!new || !old) { return 0; } kuid_t new_uid = new->uid; kuid_t old_uid = old->uid; // pr_info("handle_setuid from %d to %d\n", old_uid.val, new_uid.val); if (0 != old_uid.val) { // old process is not root, ignore it. if (ksu_enhanced_security_enabled) { // disallow any non-ksu domain escalation from non-root to root! if (unlikely(new_uid.val) == 0) { if (!is_ksu_domain()) { pr_warn("find suspicious EoP: %d %s, from %d to %d\n", current->pid, current->comm, old_uid.val, new_uid.val); kill_pgrp(SIGKILL, current, 0); return 0; } } // disallow appuid decrease to any other uid if it is allowed to su if (is_appuid(old_uid)) { if (new_uid.val < old_uid.val && !ksu_is_allow_uid_for_current(old_uid.val)) { pr_warn("find suspicious EoP: %d %s, from %d to %d\n", current->pid, current->comm, old_uid.val, new_uid.val); kill_pgrp(SIGKILL, current, 0); return 0; } } } return 0; } if (new_uid.val == 2000) { if (ksu_su_compat_enabled) { ksu_set_task_tracepoint_flag(current); } } if (!is_appuid(new_uid) || is_unsupported_uid(new_uid.val)) { // pr_info("handle setuid ignore non application or isolated uid: %d\n", new_uid.val); return 0; } // if on private space, see if its possibly the manager if (new_uid.val > 100000 && new_uid.val % 100000 == ksu_get_manager_uid()) { ksu_set_manager_uid(new_uid.val); } if (ksu_get_manager_uid() == new_uid.val) { pr_info("install fd for: %d\n", new_uid.val); ksu_install_fd(); spin_lock_irq(¤t->sighand->siglock); ksu_seccomp_allow_cache(current->seccomp.filter, __NR_reboot); if (ksu_su_compat_enabled) { ksu_set_task_tracepoint_flag(current); } spin_unlock_irq(¤t->sighand->siglock); return 0; } if (ksu_is_allow_uid_for_current(new_uid.val)) { if (current->seccomp.mode == SECCOMP_MODE_FILTER && current->seccomp.filter) { spin_lock_irq(¤t->sighand->siglock); ksu_seccomp_allow_cache(current->seccomp.filter, __NR_reboot); spin_unlock_irq(¤t->sighand->siglock); } if (ksu_su_compat_enabled) { ksu_set_task_tracepoint_flag(current); } } else { // Disable syscall tracepoint sucompat for non-allowed processes if (ksu_su_compat_enabled) { ksu_clear_task_tracepoint_flag(current); } } // this hook is used for umounting overlayfs for some uid, if there isn't any module mounted, just ignore it! if (!ksu_module_mounted) { return 0; } if (!ksu_kernel_umount_enabled) { return 0; } if (!ksu_uid_should_umount(new_uid.val)) { return 0; } else { #ifdef CONFIG_KSU_DEBUG pr_info("uid: %d should not umount!\n", current_uid().val); #endif } // check old process's selinux context, if it is not zygote, ignore it! // because some su apps may setuid to untrusted_app but they are in global mount namespace // when we umount for such process, that is a disaster! bool is_zygote_child = is_zygote(old); if (!is_zygote_child) { pr_info("handle umount ignore non zygote child: %d\n", current->pid); return 0; } #if __SULOG_GATE ksu_sulog_report_syscall(new_uid.val, NULL, "setuid", NULL); #endif #ifdef CONFIG_KSU_DEBUG // umount the target mnt pr_info("handle umount for uid: %d, pid: %d\n", new_uid.val, current->pid); #endif tw = kmalloc(sizeof(*tw), GFP_ATOMIC); if (!tw) return 0; tw->old_cred = get_current_cred(); tw->cb.func = umount_tw_func; int err = task_work_add(current, &tw->cb, TWA_RESUME); if (err) { if (tw->old_cred) { put_cred(tw->old_cred); } kfree(tw); pr_warn("unmount add task_work failed\n"); } return 0; } // downstream: make sure to pass arg as reference, this can allow us to extend things. int ksu_handle_sys_reboot(int magic1, int magic2, unsigned int cmd, void __user **arg) { if (magic1 != KSU_INSTALL_MAGIC1) return 0; #ifdef CONFIG_KSU_DEBUG pr_info("sys_reboot: intercepted call! magic: 0x%x id: %d\n", magic1, magic2); #endif // Check if this is a request to install KSU fd if (magic2 == KSU_INSTALL_MAGIC2) { int fd = ksu_install_fd(); pr_info("[%d] install ksu fd: %d\n", current->pid, fd); // downstream: dereference all arg usage! if (copy_to_user((void __user *)*arg, &fd, sizeof(fd))) { pr_err("install ksu fd reply err\n"); } return 0; } // extensions return 0; } // Init functons - kprobe hooks // 1. Reboot hook for installing fd static int reboot_handler_pre(struct kprobe *p, struct pt_regs *regs) { struct pt_regs *real_regs = PT_REAL_REGS(regs); int magic1 = (int)PT_REGS_PARM1(real_regs); int magic2 = (int)PT_REGS_PARM2(real_regs); int cmd = (int)PT_REGS_PARM3(real_regs); void __user **arg = (void __user **)&PT_REGS_SYSCALL_PARM4(real_regs); return ksu_handle_sys_reboot(magic1, magic2, cmd, arg); } static struct kprobe reboot_kp = { .symbol_name = REBOOT_SYMBOL, .pre_handler = reboot_handler_pre, }; // 2. cap_task_fix_setuid hook for handling setuid static int cap_task_fix_setuid_handler_pre(struct kprobe *p, struct pt_regs *regs) { struct cred *new = (struct cred *)PT_REGS_PARM1(regs); const struct cred *old = (const struct cred *)PT_REGS_PARM2(regs); ksu_handle_setuid(new, old); return 0; } static struct kprobe cap_task_fix_setuid_kp = { .symbol_name = "cap_task_fix_setuid", .pre_handler = cap_task_fix_setuid_handler_pre, }; // 3.inode_permission hook for handling devpts static int ksu_inode_permission_handler_pre(struct kprobe *p, struct pt_regs *regs) { struct inode *inode = (struct inode *)PT_REGS_PARM1(regs); if (inode && inode->i_sb && unlikely(inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC)) { // pr_info("%s: handling devpts for: %s \n", __func__, current->comm); __ksu_handle_devpts(inode); } return 0; } static struct kprobe ksu_inode_permission_kp = { .symbol_name = "security_inode_permission", .pre_handler = ksu_inode_permission_handler_pre, }; // 4. bprm_check_security hook for handling ksud compatibility static int ksu_bprm_check_handler_pre(struct kprobe *p, struct pt_regs *regs) { struct linux_binprm *bprm = (struct linux_binprm *)PT_REGS_PARM1(regs); char *filename = (char *)bprm->filename; if (likely(!ksu_execveat_hook)) return 0; #ifdef CONFIG_COMPAT static bool compat_check_done __read_mostly = false; if (unlikely(!compat_check_done) && unlikely(!strcmp(filename, "/data/adb/ksud")) && !memcmp(bprm->buf, "\x7f\x45\x4c\x46", 4)) { if (bprm->buf[4] == 0x01) ksu_is_compat = true; pr_info("%s: %s ELF magic found! ksu_is_compat: %d \n", __func__, filename, ksu_is_compat); compat_check_done = true; } #endif ksu_handle_pre_ksud(filename); #ifdef CONFIG_KSU_MANUAL_SU ksu_try_escalate_for_uid(current_uid().val); #endif return 0; } static struct kprobe ksu_bprm_check_kp = { .symbol_name = "security_bprm_check", .pre_handler = ksu_bprm_check_handler_pre, }; #ifdef CONFIG_KSU_MANUAL_SU // 5. task_alloc hook for handling manual su escalation static int ksu_task_alloc_handler_pre(struct kprobe *p, struct pt_regs *regs) { struct task_struct *task = (struct task_struct *)PT_REGS_PARM1(regs); ksu_try_escalate_for_uid(task_uid(task).val); return 0; } static struct kprobe ksu_task_alloc_kp = { .symbol_name = "security_task_alloc", .pre_handler = ksu_task_alloc_handler_pre, }; #endif __maybe_unused int ksu_kprobe_init(void) { int rc = 0; // Register reboot kprobe rc = register_kprobe(&reboot_kp); if (rc) { pr_err("reboot kprobe failed: %d\n", rc); } else { pr_info("reboot kprobe registered successfully\n"); } rc = register_kprobe(&cap_task_fix_setuid_kp); if (rc) { pr_err("cap_task_fix_setuid kprobe failed: %d\n", rc); unregister_kprobe(&reboot_kp); } else { pr_info("cap_task_fix_setuid_kp kprobe registered successfully\n"); } // Register inode_permission kprobe rc = register_kprobe(&ksu_inode_permission_kp); if (rc) { pr_err("inode_permission kprobe failed: %d\n", rc); } else { pr_info("inode_permission kprobe registered successfully\n"); } // Register bprm_check_security kprobe rc = register_kprobe(&ksu_bprm_check_kp); if (rc) { pr_err("bprm_check_security kprobe failed: %d\n", rc); } else { pr_info("bprm_check_security kprobe registered successfully\n"); } #ifdef CONFIG_KSU_MANUAL_SU // Register task_alloc kprobe rc = register_kprobe(&ksu_task_alloc_kp); if (rc) { pr_err("task_alloc kprobe failed: %d\n", rc); } else { pr_info("task_alloc kprobe registered successfully\n"); } #endif return 0; } __maybe_unused int ksu_kprobe_exit(void) { unregister_kprobe(&reboot_kp); unregister_kprobe(&cap_task_fix_setuid_kp); unregister_kprobe(&ksu_inode_permission_kp); unregister_kprobe(&ksu_bprm_check_kp); #ifdef CONFIG_KSU_MANUAL_SU unregister_kprobe(&ksu_task_alloc_kp); #endif return 0; } void __init ksu_core_init(void) { int rc = 0; #ifdef CONFIG_KPROBES rc = ksu_kprobe_init(); if (rc) { pr_err("ksu_kprobe_init failed: %d\n", rc); } #endif rc = ksu_umount_manager_init(); if (rc) { pr_err("Failed to initialize umount manager: %d\n", rc); } if (ksu_register_feature_handler(&kernel_umount_handler)) { pr_err("Failed to register umount feature handler\n"); } if (ksu_register_feature_handler(&enhanced_security_handler)) { pr_err("Failed to register enhanced security feature handler\n"); } } void ksu_core_exit(void) { ksu_uid_exit(); ksu_throne_comm_exit(); #if __SULOG_GATE ksu_sulog_exit(); #endif #ifdef CONFIG_KPROBES pr_info("ksu_core_exit\n"); ksu_kprobe_exit(); #endif ksu_unregister_feature_handler(KSU_FEATURE_KERNEL_UMOUNT); ksu_unregister_feature_handler(KSU_FEATURE_ENHANCED_SECURITY); }