kernel: refact (#113)
* refact
* sort inlude
* update
* unregister execve kprobe
* update log
* don't unregister if not in kprobe
* opt for no kprobe
* opt for no kprobe
* stop debug
* don't forget to call ksu_uid_observer_exit
* rename core to core_hook
* direct call do_persistent_allow_list
* add prefix
* use getter, add warn
* add wrapper
* run clang-format
clang-format --style="{BasedOnStyle: InheritParentConfig, SortIncludes: true}" -i kernel/**/*.[ch]
* try fix wsa x64 build
This commit is contained in:
Ylarod
GitHub
262
kernel/ksud.c
Normal file
262
kernel/ksud.c
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#include "asm/current.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/kprobes.h"
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#include "linux/printk.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/workqueue.h"
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#include "allowlist.h"
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#include "arch.h"
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#include "selinux/selinux.h"
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static const char KERNEL_SU_RC[] =
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"\n"
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"on post-fs-data\n"
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// We should wait for the post-fs-data finish
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" exec u:r:su:s0 root -- /data/adb/ksud post-fs-data\n"
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"\n"
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"on nonencrypted\n"
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" exec u:r:su:s0 root -- /data/adb/ksud services\n"
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"\n"
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"on property:vold.decrypt=trigger_restart_framework\n"
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" exec u:r:su:s0 root -- /data/adb/ksud services\n"
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"\n"
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"on property:sys.boot_completed=1\n"
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" exec u:r:su:s0 root -- /data/adb/ksud boot-completed\n"
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"\n"
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"\n";
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static void stop_vfs_read_hook();
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static void stop_execve_hook();
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#ifdef CONFIG_KPROBES
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static struct work_struct stop_vfs_read_work;
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static struct work_struct stop_execve_hook_work;
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#else
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static bool vfs_read_hook = true;
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static bool execveat_hook = true;
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#endif
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int ksu_handle_execveat_ksud(int *fd, struct filename **filename_ptr,
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void *argv, void *envp, int *flags)
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{
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#ifndef CONFIG_KPROBES
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if (!execveat_hook) {
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return 0;
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}
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#endif
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struct filename *filename;
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static const char app_process[] = "/system/bin/app_process";
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static bool first_app_process = true;
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static const char system_bin_init[] = "/system/bin/init";
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static int init_count = 0;
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if (!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 (!memcmp(filename->name, system_bin_init,
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sizeof(system_bin_init) - 1)) {
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// /system/bin/init executed
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if (++init_count == 2) {
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// 1: /system/bin/init selinux_setup
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// 2: /system/bin/init second_stage
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pr_info("/system/bin/init second_stage executed\n");
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apply_kernelsu_rules();
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}
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}
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if (first_app_process &&
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!memcmp(filename->name, app_process, sizeof(app_process) - 1)) {
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first_app_process = false;
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pr_info("exec app_process, /data prepared!\n");
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ksu_load_allow_list();
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stop_execve_hook();
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}
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return 0;
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}
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int ksu_handle_vfs_read(struct file **file_ptr, char __user **buf_ptr,
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size_t *count_ptr, loff_t **pos)
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{
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#ifndef CONFIG_KPROBES
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if (!vfs_read_hook) {
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return 0;
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}
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#endif
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struct file *file;
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char __user *buf;
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size_t count;
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if (strcmp(current->comm, "init")) {
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// we are only interest in `init` process
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return 0;
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}
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file = *file_ptr;
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if (IS_ERR(file)) {
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return 0;
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}
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if (!d_is_reg(file->f_path.dentry)) {
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return 0;
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}
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const char *short_name = file->f_path.dentry->d_name.name;
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if (strcmp(short_name, "atrace.rc")) {
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// we are only interest `atrace.rc` file name file
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return 0;
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}
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char path[256];
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char *dpath = d_path(&file->f_path, path, sizeof(path));
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if (IS_ERR(dpath)) {
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return 0;
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}
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if (strcmp(dpath, "/system/etc/init/atrace.rc")) {
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return 0;
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}
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// we only process the first read
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static bool rc_inserted = false;
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if (rc_inserted) {
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// we don't need this kprobe, unregister it!
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stop_vfs_read_hook();
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return 0;
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}
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rc_inserted = true;
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// now we can sure that the init process is reading
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// `/system/etc/init/atrace.rc`
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buf = *buf_ptr;
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count = *count_ptr;
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size_t rc_count = strlen(KERNEL_SU_RC);
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pr_info("vfs_read: %s, comm: %s, count: %d, rc_count: %d\n", dpath,
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current->comm, count, rc_count);
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if (count < rc_count) {
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pr_err("count: %d < rc_count: %d", count, rc_count);
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return 0;
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}
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size_t ret = copy_to_user(buf, KERNEL_SU_RC, rc_count);
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if (ret) {
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pr_err("copy ksud.rc failed: %d\n", ret);
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return 0;
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}
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*buf_ptr = buf + rc_count;
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*count_ptr = count - rc_count;
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return 0;
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}
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#ifdef CONFIG_KPROBES
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// https://elixir.bootlin.com/linux/v5.10.158/source/fs/exec.c#L1864
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static int execve_handler_pre(struct kprobe *p, struct pt_regs *regs)
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{
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int *fd = (int *)&PT_REGS_PARM1(regs);
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struct filename **filename_ptr =
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(struct filename **)&PT_REGS_PARM2(regs);
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void *argv = (void *)&PT_REGS_PARM3(regs);
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void *envp = (void *)&PT_REGS_PARM4(regs);
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int *flags = (int *)&PT_REGS_PARM5(regs);
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return ksu_handle_execveat_ksud(fd, filename_ptr, argv, envp, flags);
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}
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static int read_handler_pre(struct kprobe *p, struct pt_regs *regs)
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{
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struct file **file_ptr = (struct file **)&PT_REGS_PARM1(regs);
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char __user **buf_ptr = (char **)&PT_REGS_PARM2(regs);
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size_t *count_ptr = (size_t *)&PT_REGS_PARM3(regs);
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loff_t **pos_ptr = (loff_t **)&PT_REGS_PARM4(regs);
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return ksu_handle_vfs_read(file_ptr, buf_ptr, count_ptr, pos_ptr);
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}
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static struct kprobe execve_kp = {
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#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 9, 0)
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.symbol_name = "do_execveat_common",
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#elif LINUX_VERSION_CODE >= KERNEL_VERSION(4, 19, 0) && \
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LINUX_VERSION_CODE < KERNEL_VERSION(5, 9, 0)
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.symbol_name = "__do_execve_file",
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#elif LINUX_VERSION_CODE >= KERNEL_VERSION(4, 14, 0) && \
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LINUX_VERSION_CODE < KERNEL_VERSION(4, 19, 0)
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.symbol_name = "do_execveat_common",
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#endif
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.pre_handler = execve_handler_pre,
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};
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static struct kprobe vfs_read_kp = {
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.symbol_name = "vfs_read",
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.pre_handler = read_handler_pre,
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};
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static void do_stop_vfs_read_hook(struct work_struct *work)
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{
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unregister_kprobe(&vfs_read_kp);
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}
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static void do_stop_execve_hook(struct work_struct *work)
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{
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unregister_kprobe(&execve_kp);
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}
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#endif
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static void stop_vfs_read_hook()
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{
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#ifdef CONFIG_KPROBES
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bool ret = schedule_work(&stop_vfs_read_work);
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pr_info("unregister vfs_read kprobe: %d!\n", ret);
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#else
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vfs_read_hook = false;
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#endif
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}
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static void stop_execve_hook()
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{
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#ifdef CONFIG_KPROBES
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bool ret = schedule_work(&stop_execve_hook_work);
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pr_info("unregister execve kprobe: %d!\n", ret);
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#else
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execveat_hook = false;
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#endif
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}
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// ksud: module support
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void ksu_enable_ksud()
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{
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#ifdef CONFIG_KPROBES
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int ret;
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ret = register_kprobe(&execve_kp);
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pr_info("ksud: execve_kp: %d\n", ret);
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ret = register_kprobe(&vfs_read_kp);
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pr_info("ksud: vfs_read_kp: %d\n", ret);
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INIT_WORK(&stop_vfs_read_work, do_stop_vfs_read_hook);
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INIT_WORK(&stop_execve_hook_work, do_stop_execve_hook);
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#endif
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}
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