kernel: Rewrite the kernel source code (#554)

* clean unused header * on_module_mounted in ksud.c * refact: use app_profile * unified hook manager * add zygote to hook target * move reboot hook to supercall.c * refactor: kernel_umount setuid_hook * update mark rules, add init mark tracker * remove reboot from check_syscall_fastpath * update setuid_hook, remove uneeded sucompat enable * log freely * kernel: Migrate kprobe hook configuration items * kernel: fix build * cli: add ksud debug mark * Fix rustfmt warning --------- Co-authored-by: Ylarod <me@ylarod.cn> Co-authored-by: Wang Han <416810799@qq.com> Co-authored-by: ShirkNeko <109797057+ShirkNeko@users.noreply.github.com>
2025-11-09 01:14:26 +08:00
parent 678c00cad9
commit af4b502631
27 changed files with 1567 additions and 1374 deletions
--- a/kernel/app_profile.c
+++ b/kernel/app_profile.c
@@ -0,0 +1,277 @@
+#include <linux/capability.h>
+#include <linux/cred.h>
+#include <linux/sched.h>
+#include <linux/sched/signal.h>
+#include <linux/seccomp.h>
+#include <linux/thread_info.h>
+#include <linux/uidgid.h>
+#include <linux/version.h>
+
+#include "allowlist.h"
+#include "app_profile.h"
+#include "klog.h" // IWYU pragma: keep
+#include "selinux/selinux.h"
+#include "syscall_hook_manager.h"
+#include "sucompat.h"
+
+#include "sulog.h"
+#include "kprobe_hook_manager.h"
+
+
+#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;
+        }
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 9, 0)
+        group_info->gid[i] = kgid;
+#else
+        GROUP_AT(group_info, i) = kgid;
+#endif
+    }
+
+    groups_sort(group_info);
+    set_groups(cred, group_info);
+    put_group_info(group_info);
+}
+
+static void disable_seccomp()
+{
+    assert_spin_locked(&current->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_with_root_profile(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(&current->sighand->siglock);
+    disable_seccomp();
+    spin_unlock_irq(&current->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