530 lines
14 KiB
C
530 lines
14 KiB
C
#include "linux/compiler.h"
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#include "linux/printk.h"
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#include "linux/sched.h"
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#include "selinux/selinux.h"
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#include <linux/dcache.h>
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#include <linux/security.h>
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#include <asm/current.h>
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#include <linux/cred.h>
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#include <linux/err.h>
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#include <linux/fs.h>
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#include <linux/kprobes.h>
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#include <linux/tracepoint.h>
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#include <linux/types.h>
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#include <linux/uaccess.h>
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#include <linux/version.h>
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#include <linux/spinlock.h>
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#include <linux/sched/task_stack.h>
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#include <asm/syscall.h>
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#include <trace/events/syscalls.h>
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#include "objsec.h"
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#include "allowlist.h"
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#include "arch.h"
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#include "feature.h"
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#include "klog.h" // IWYU pragma: keep
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#include "ksud.h"
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#include "sucompat.h"
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#include "core_hook.h"
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#include "sulog.h"
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#define SU_PATH "/system/bin/su"
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#define SH_PATH "/system/bin/sh"
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bool ksu_su_compat_enabled __read_mostly = true;
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extern void escape_to_root();
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void ksu_sucompat_enable();
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void ksu_sucompat_disable();
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void ksu_mark_running_process(void)
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{
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struct task_struct *p, *t;
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read_lock(&tasklist_lock);
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for_each_process_thread (p, t) {
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if (!t->mm) { // only user processes
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continue;
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}
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int uid = task_uid(t).val;
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bool ksu_root_process =
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uid == 0 && is_task_ksu_domain(get_task_cred(t));
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if (ksu_root_process || ksu_is_allow_uid(uid)) {
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ksu_set_task_tracepoint_flag(t);
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pr_info("sucompat: mark process: pid:%d, uid: %d, comm:%s\n",
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t->pid, uid, t->comm);
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}
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}
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read_unlock(&tasklist_lock);
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}
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static void handle_process_mark(bool mark)
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{
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struct task_struct *p, *t;
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read_lock(&tasklist_lock);
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for_each_process_thread(p, t) {
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if (mark)
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ksu_set_task_tracepoint_flag(t);
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else
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ksu_clear_task_tracepoint_flag(t);
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}
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read_unlock(&tasklist_lock);
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}
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static void mark_all_process(void)
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{
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handle_process_mark(true);
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pr_info("sucompat: mark all user process done!\n");
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}
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static void unmark_all_process(void)
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{
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handle_process_mark(false);
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pr_info("sucompat: unmark all user process done!\n");
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}
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static int su_compat_feature_get(u64 *value)
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{
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*value = ksu_su_compat_enabled ? 1 : 0;
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return 0;
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}
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static int su_compat_feature_set(u64 value)
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{
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bool enable = value != 0;
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if (enable == ksu_su_compat_enabled) {
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pr_info("su_compat: no need to change\n");
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return 0;
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}
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if (enable) {
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ksu_sucompat_enable();
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} else {
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ksu_sucompat_disable();
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}
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ksu_su_compat_enabled = enable;
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pr_info("su_compat: 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 su_compat_handler = {
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.feature_id = KSU_FEATURE_SU_COMPAT,
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.name = "su_compat",
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.get_handler = su_compat_feature_get,
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.set_handler = su_compat_feature_set,
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};
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#ifndef KSU_HAVE_SYSCALL_TRACEPOINTS_HOOK
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static bool ksu_sucompat_hook_state __read_mostly = true;
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#endif
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static void __user *userspace_stack_buffer(const void *d, size_t len)
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{
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/* To avoid having to mmap a page in userspace, just write below the stack
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* pointer. */
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char __user *p = (void __user *)current_user_stack_pointer() - len;
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return copy_to_user(p, d, len) ? NULL : p;
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}
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static char __user *sh_user_path(void)
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{
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static const char sh_path[] = "/system/bin/sh";
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return userspace_stack_buffer(sh_path, sizeof(sh_path));
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}
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static char __user *ksud_user_path(void)
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{
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static const char ksud_path[] = KSUD_PATH;
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return userspace_stack_buffer(ksud_path, sizeof(ksud_path));
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}
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int ksu_handle_faccessat(int *dfd, const char __user **filename_user, int *mode,
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int *__unused_flags)
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{
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const char su[] = SU_PATH;
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#ifndef KSU_HAVE_SYSCALL_TRACEPOINTS_HOOK
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if (!ksu_sucompat_hook_state) {
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return 0;
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}
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#endif
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if (!ksu_is_allow_uid_for_current(current_uid().val)) {
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return 0;
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}
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char path[sizeof(su) + 1];
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memset(path, 0, sizeof(path));
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strncpy_from_user_nofault(path, *filename_user, sizeof(path));
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if (unlikely(!memcmp(path, su, sizeof(su)))) {
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#if __SULOG_GATE
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ksu_sulog_report_syscall(current_uid().val, NULL, "faccessat", path);
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#endif
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pr_info("faccessat su->sh!\n");
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*filename_user = sh_user_path();
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}
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return 0;
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}
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int ksu_handle_stat(int *dfd, const char __user **filename_user, int *flags)
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{
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// const char sh[] = SH_PATH;
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const char su[] = SU_PATH;
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#ifndef KSU_HAVE_SYSCALL_TRACEPOINTS_HOOK
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if (!ksu_sucompat_hook_state) {
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return 0;
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}
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#endif
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if (!ksu_is_allow_uid_for_current(current_uid().val)) {
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return 0;
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}
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if (unlikely(!filename_user)) {
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return 0;
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}
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char path[sizeof(su) + 1];
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memset(path, 0, sizeof(path));
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// Remove this later!! we use syscall hook, so this will never happen!!!!!
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#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 18, 0) && 0
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// it becomes a `struct filename *` after 5.18
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// https://elixir.bootlin.com/linux/v5.18/source/fs/stat.c#L216
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const char sh[] = SH_PATH;
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struct filename *filename = *((struct filename **)filename_user);
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if (IS_ERR(filename)) {
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return 0;
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}
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if (likely(memcmp(filename->name, su, sizeof(su))))
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return 0;
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pr_info("vfs_statx su->sh!\n");
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memcpy((void *)filename->name, sh, sizeof(sh));
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#else
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strncpy_from_user_nofault(path, *filename_user, sizeof(path));
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if (unlikely(!memcmp(path, su, sizeof(su)))) {
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#if __SULOG_GATE
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ksu_sulog_report_syscall(current_uid().val, NULL, "newfstatat", path);
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#endif
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pr_info("newfstatat su->sh!\n");
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*filename_user = sh_user_path();
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}
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#endif
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return 0;
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}
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// the call from execve_handler_pre won't provided correct value for __never_use_argument, use them after fix execve_handler_pre, keeping them for consistence for manually patched code
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int ksu_handle_execveat_sucompat(int *fd, struct filename **filename_ptr,
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void *__never_use_argv, void *__never_use_envp,
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int *__never_use_flags)
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{
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struct filename *filename;
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const char sh[] = KSUD_PATH;
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const char su[] = SU_PATH;
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#ifndef KSU_HAVE_SYSCALL_TRACEPOINTS_HOOK
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if (!ksu_sucompat_hook_state) {
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return 0;
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}
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#endif
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if (unlikely(!filename_ptr))
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return 0;
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filename = *filename_ptr;
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if (IS_ERR(filename)) {
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return 0;
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}
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if (likely(memcmp(filename->name, su, sizeof(su))))
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return 0;
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#if __SULOG_GATE
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bool is_allowed = ksu_is_allow_uid_for_current(current_uid().val);
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ksu_sulog_report_syscall(current_uid().val, NULL, "execve", filename->name);
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if (!is_allowed) {
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return 0;
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}
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ksu_sulog_report_su_attempt(current_uid().val, NULL, filename->name, is_allowed);
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#else
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if (!ksu_is_allow_uid_for_current(current_uid().val)) {
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return 0;
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}
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#endif
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pr_info("do_execveat_common su found\n");
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memcpy((void *)filename->name, sh, sizeof(sh));
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escape_to_root();
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return 0;
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}
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int ksu_handle_execveat(int *fd, struct filename **filename_ptr, void *argv,
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void *envp, int *flags)
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{
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return ksu_handle_execveat_sucompat(fd, filename_ptr, argv, envp, flags);
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}
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int ksu_handle_execve_sucompat(int *fd, const char __user **filename_user,
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void *__never_use_argv, void *__never_use_envp,
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int *__never_use_flags)
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{
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const char su[] = SU_PATH;
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char path[sizeof(su) + 1];
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#ifndef KSU_HAVE_SYSCALL_TRACEPOINTS_HOOK
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if (!ksu_sucompat_hook_state){
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return 0;
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}
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#endif
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if (unlikely(!filename_user))
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return 0;
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memset(path, 0, sizeof(path));
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strncpy_from_user_nofault(path, *filename_user, sizeof(path));
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if (likely(memcmp(path, su, sizeof(su))))
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return 0;
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#if __SULOG_GATE
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bool is_allowed = ksu_is_allow_uid_for_current(current_uid().val);
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ksu_sulog_report_syscall(current_uid().val, NULL, "execve", path);
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if (!is_allowed)
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return 0;
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ksu_sulog_report_su_attempt(current_uid().val, NULL, path, is_allowed);
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#else
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if (!ksu_is_allow_uid_for_current(current_uid().val)) {
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return 0;
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}
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#endif
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pr_info("sys_execve su found\n");
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*filename_user = ksud_user_path();
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escape_to_root();
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return 0;
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}
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int __ksu_handle_devpts(struct inode *inode)
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{
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#ifndef KSU_HAVE_SYSCALL_TRACEPOINTS_HOOK
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if (!ksu_sucompat_hook_state)
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return 0;
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#endif
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if (!current->mm) {
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return 0;
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}
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uid_t uid = current_uid().val;
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if (uid % 100000 < 10000) {
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// not untrusted_app, ignore it
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return 0;
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}
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if (likely(!ksu_is_allow_uid_for_current(uid)))
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return 0;
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struct inode_security_struct *sec = selinux_inode(inode);
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if (ksu_file_sid && sec)
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sec->sid = ksu_file_sid;
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return 0;
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}
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#ifdef KSU_HAVE_SYSCALL_TRACEPOINTS_HOOK
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// Tracepoint probe for sys_enter
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static void sucompat_sys_enter_handler(void *data, struct pt_regs *regs,
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long id)
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{
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// Handle newfstatat
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if (unlikely(id == __NR_newfstatat)) {
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int *dfd = (int *)&PT_REGS_PARM1(regs);
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const char __user **filename_user =
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(const char __user **)&PT_REGS_PARM2(regs);
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int *flags = (int *)&PT_REGS_SYSCALL_PARM4(regs);
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ksu_handle_stat(dfd, filename_user, flags);
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return;
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}
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// Handle faccessat
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if (unlikely(id == __NR_faccessat)) {
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int *dfd = (int *)&PT_REGS_PARM1(regs);
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const char __user **filename_user =
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(const char __user **)&PT_REGS_PARM2(regs);
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int *mode = (int *)&PT_REGS_PARM3(regs);
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ksu_handle_faccessat(dfd, filename_user, mode, NULL);
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return;
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}
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// Handle execve
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if (unlikely(id == __NR_execve)) {
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const char __user **filename_user =
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(const char __user **)&PT_REGS_PARM1(regs);
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ksu_handle_execve_sucompat(AT_FDCWD, filename_user, NULL, NULL, NULL);
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return;
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}
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}
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#endif // KSU_HAVE_SYSCALL_TRACEPOINTS_HOOK
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#ifdef CONFIG_KRETPROBES
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static struct kretprobe *init_kretprobe(const char *name,
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kretprobe_handler_t handler)
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{
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struct kretprobe *rp = kzalloc(sizeof(struct kretprobe), GFP_KERNEL);
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if (!rp)
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return NULL;
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rp->kp.symbol_name = name;
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rp->handler = handler;
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rp->data_size = 0;
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rp->maxactive = 0;
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int ret = register_kretprobe(rp);
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pr_info("sucompat: register_%s kretprobe: %d\n", name, ret);
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if (ret) {
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kfree(rp);
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return NULL;
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}
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return rp;
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}
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static void destroy_kretprobe(struct kretprobe **rp_ptr)
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{
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struct kretprobe *rp = *rp_ptr;
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if (!rp)
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return;
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unregister_kretprobe(rp);
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synchronize_rcu();
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kfree(rp);
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*rp_ptr = NULL;
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}
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#endif
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#ifdef CONFIG_KRETPROBES
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static int tracepoint_reg_count = 0;
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static DEFINE_SPINLOCK(tracepoint_reg_lock);
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static int syscall_regfunc_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
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{
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unsigned long flags;
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spin_lock_irqsave(&tracepoint_reg_lock, flags);
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if (tracepoint_reg_count < 1) {
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// while install our tracepoint, mark our processes
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unmark_all_process();
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ksu_mark_running_process();
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} else {
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// while installing other tracepoint, mark all processes
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mark_all_process();
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}
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tracepoint_reg_count++;
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spin_unlock_irqrestore(&tracepoint_reg_lock, flags);
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return 0;
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}
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static int syscall_unregfunc_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
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{
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unsigned long flags;
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spin_lock_irqsave(&tracepoint_reg_lock, flags);
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if (tracepoint_reg_count <= 1) {
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// while uninstall our tracepoint, unmark all processes
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unmark_all_process();
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} else {
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// while uninstalling other tracepoint, mark our processes
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unmark_all_process();
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ksu_mark_running_process();
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}
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tracepoint_reg_count--;
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spin_unlock_irqrestore(&tracepoint_reg_lock, flags);
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return 0;
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}
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static struct kretprobe *syscall_regfunc_rp = NULL;
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static struct kretprobe *syscall_unregfunc_rp = NULL;
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#endif
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void ksu_sucompat_enable()
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{
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int ret;
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pr_info("sucompat: ksu_sucompat_enable called\n");
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#ifdef CONFIG_KRETPROBES
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// Register kretprobe for syscall_regfunc
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syscall_regfunc_rp = init_kretprobe("syscall_regfunc", syscall_regfunc_handler);
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// Register kretprobe for syscall_unregfunc
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syscall_unregfunc_rp = init_kretprobe("syscall_unregfunc", syscall_unregfunc_handler);
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#endif
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#ifdef KSU_HAVE_SYSCALL_TRACEPOINTS_HOOK
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ret = register_trace_sys_enter(sucompat_sys_enter_handler, NULL);
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#ifndef CONFIG_KRETPROBES
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unmark_all_process();
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ksu_mark_running_process();
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#endif
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if (ret) {
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pr_err("sucompat: failed to register sys_enter tracepoint: %d\n", ret);
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} else {
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pr_info("sucompat: sys_enter tracepoint registered\n");
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}
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#else
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ksu_sucompat_hook_state = true;
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pr_info("ksu_sucompat_init: hooks enabled: execve/execveat_su, faccessat, stat\n");
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#endif
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}
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void ksu_sucompat_disable()
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{
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pr_info("sucompat: ksu_sucompat_disable called\n");
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#ifdef KSU_HAVE_SYSCALL_TRACEPOINTS_HOOK
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unregister_trace_sys_enter(sucompat_sys_enter_handler, NULL);
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tracepoint_synchronize_unregister();
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pr_info("sucompat: sys_enter tracepoint unregistered\n");
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#else
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ksu_sucompat_hook_state = false;
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pr_info("ksu_sucompat_exit: hooks disabled: execve/execveat_su, faccessat, stat\n");
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#endif
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#ifdef CONFIG_KRETPROBES
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destroy_kretprobe(&syscall_regfunc_rp);
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destroy_kretprobe(&syscall_unregfunc_rp);
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#endif
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}
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// sucompat: permited process can execute 'su' to gain root access.
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void ksu_sucompat_init()
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{
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if (ksu_register_feature_handler(&su_compat_handler)) {
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pr_err("Failed to register su_compat feature handler\n");
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}
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if (ksu_su_compat_enabled) {
|
|
ksu_sucompat_enable();
|
|
}
|
|
}
|
|
|
|
void ksu_sucompat_exit()
|
|
{
|
|
if (ksu_su_compat_enabled) {
|
|
ksu_sucompat_disable();
|
|
}
|
|
ksu_unregister_feature_handler(KSU_FEATURE_SU_COMPAT);
|
|
} |