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kernel: Update sucompat.c to improve hook state management and code clarity

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Co-authored-by: rsuntk <90097027+rsuntk@users.noreply.github.com>
This commit is contained in:
ShirkNeko
2025-06-12 15:53:17 +08:00
parent ad2721c050
commit 87b57d9eba
1 changed files with 80 additions and 96 deletions
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176
kernel/sucompat.c
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@@ -8,14 +8,15 @@
#include <linux/types.h>
#include <linux/uaccess.h>
#include <linux/version.h>
#include <linux/ptrace.h>
#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 11, 0)
#include <linux/sched/task_stack.h>
#ifdef CONFIG_KSU_SUSFS_SUS_SU
#include <linux/susfs_def.h>
#endif
#else
#include <linux/sched.h>
#endif
#ifdef CONFIG_KSU_SUSFS_SUS_SU
#include <linux/susfs_def.h>
#endif
#include "objsec.h"
#include "allowlist.h"
@@ -27,16 +28,10 @@
#define SU_PATH "/system/bin/su"
#define SH_PATH "/system/bin/sh"
#ifndef CONFIG_KSU_KPROBES_HOOK
static bool ksu_sucompat_non_kp __read_mostly = true;
#endif
#ifndef CONFIG_KSU_SUSFS_SUS_SU
bool ksu_devpts_hook __read_mostly = true;
#endif
extern void ksu_escape_to_root();
bool ksu_sucompat_hook_state __read_mostly = true;
static void __user *userspace_stack_buffer(const void *d, size_t len)
{
/* To avoid having to mmap a page in userspace, just write below the stack
@@ -48,8 +43,9 @@ static void __user *userspace_stack_buffer(const void *d, size_t len)
static char __user *sh_user_path(void)
{
static const char sh_path[] = SH_PATH;
return userspace_stack_buffer(sh_path, sizeof(sh_path));
static const char sh_path[] = "/system/bin/sh";
return userspace_stack_buffer(sh_path, sizeof(sh_path));
}
static char __user *ksud_user_path(void)
@@ -59,14 +55,16 @@ static char __user *ksud_user_path(void)
return userspace_stack_buffer(ksud_path, sizeof(ksud_path));
}
int ksu_handle_faccessat(int *dfd, const char __user **filename_user, int *mode, int *__unused_flags)
int ksu_handle_faccessat(int *dfd, const char __user **filename_user, int *mode,
int *__unused_flags)
{
const char su[] = SU_PATH;
#ifndef CONFIG_KSU_KPROBES_HOOK
if (!ksu_sucompat_non_kp) {
return 0;
}
if (!ksu_sucompat_hook_state) {
return 0;
}
#endif
if (!ksu_is_allow_uid(current_uid().val)) {
@@ -87,25 +85,26 @@ int ksu_handle_faccessat(int *dfd, const char __user **filename_user, int *mode,
#if LINUX_VERSION_CODE >= KERNEL_VERSION(6, 1, 0) && defined(CONFIG_KSU_SUSFS_SUS_SU)
struct filename* susfs_ksu_handle_stat(int *dfd, const char __user **filename_user, int *flags) {
const char su[] = SU_PATH;
struct filename *name = getname_flags(*filename_user, getname_statx_lookup_flags(*flags), NULL);
// const char sh[] = SH_PATH;
const char su[] = SU_PATH;
struct filename *name = getname_flags(*filename_user, getname_statx_lookup_flags(*flags), NULL);
if (unlikely(IS_ERR(name) || name->name == NULL)) {
return name;
}
if (unlikely(IS_ERR(name) || name->name == NULL)) {
return name;
}
if (!ksu_is_allow_uid(current_uid().val)) {
return name;
}
if (!ksu_is_allow_uid(current_uid().val)) {
return name;
}
if (likely(memcmp(name->name, su, sizeof(su)))) {
return name;
}
if (likely(memcmp(name->name, su, sizeof(su)))) {
return name;
}
const char sh[] = SH_PATH;
pr_info("vfs_fstatat su->sh!\n");
memcpy((void *)name->name, sh, sizeof(sh));
return name;
const char sh[] = SH_PATH;
pr_info("vfs_fstatat su->sh!\n");
memcpy((void *)name->name, sh, sizeof(sh));
return name;
}
#endif
@@ -115,9 +114,9 @@ int ksu_handle_stat(int *dfd, const char __user **filename_user, int *flags)
const char su[] = SU_PATH;
#ifndef CONFIG_KSU_KPROBES_HOOK
if (!ksu_sucompat_non_kp) {
return 0;
}
if (!ksu_sucompat_hook_state) {
return 0;
}
#endif
if (!ksu_is_allow_uid(current_uid().val)) {
@@ -130,79 +129,61 @@ int ksu_handle_stat(int *dfd, const char __user **filename_user, int *flags)
char path[sizeof(su) + 1];
memset(path, 0, sizeof(path));
// Remove this later!! we use syscall hook, so this will never happen!!!!!
#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 18, 0) && 0
// it becomes a `struct filename *` after 5.18
// https://elixir.bootlin.com/linux/v5.18/source/fs/stat.c#L216
const char sh[] = SH_PATH;
struct filename *filename = *((struct filename **)filename_user);
if (IS_ERR(filename)) {
return 0;
}
if (likely(memcmp(filename->name, su, sizeof(su))))
return 0;
pr_info("vfs_statx su->sh!\n");
memcpy((void *)filename->name, sh, sizeof(sh));
#else
ksu_strncpy_from_user_nofault(path, *filename_user, sizeof(path));
if (unlikely(!memcmp(path, su, sizeof(su)))) {
pr_info("newfstatat su->sh!\n");
*filename_user = sh_user_path();
}
#endif
return 0;
}
int ksu_handle_execveat_sucompat(int *fd, struct filename **filename_ptr, void *__never_use_argv, void *__never_use_envp, int *__never_use_flags)
// 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
int ksu_handle_execveat_sucompat(int *fd, struct filename **filename_ptr,
void *__never_use_argv, void *__never_use_envp,
int *__never_use_flags)
{
struct filename *filename;
const char su[] = SU_PATH;
const char ksud[] = KSUD_PATH;
const char sh[] = KSUD_PATH;
const char su[] = SU_PATH;
#ifndef CONFIG_KSU_KPROBES_HOOK
if (!ksu_sucompat_non_kp) {
return 0;
}
if (!ksu_sucompat_hook_state) {
return 0;
}
#endif
if (unlikely(!filename_ptr)) {
return 0;
}
if (unlikely(!filename_ptr))
return 0;
filename = *filename_ptr;
if (IS_ERR(filename)) {
return 0;
}
if (likely(memcmp(filename->name, su, sizeof(su))))
return 0;
if (likely(memcmp(filename->name, su, sizeof(su))))
return 0;
if (!ksu_is_allow_uid(current_uid().val))
return 0;
if (!ksu_is_allow_uid(current_uid().val))
return 0;
pr_info("do_execveat_common su found\n");
memcpy((void *)filename->name, ksud, sizeof(ksud));
pr_info("do_execveat_common su found\n");
memcpy((void *)filename->name, sh, sizeof(sh));
ksu_escape_to_root();
ksu_escape_to_root();
return 0;
return 0;
}
int ksu_handle_execve_sucompat(int *fd, const char __user **filename_user, void *__never_use_argv, void *__never_use_envp, int *__never_use_flags)
int ksu_handle_execve_sucompat(int *fd, const char __user **filename_user,
void *__never_use_argv, void *__never_use_envp,
int *__never_use_flags)
{
const char su[] = SU_PATH;
char path[sizeof(su) + 1];
#ifndef CONFIG_KSU_KPROBES_HOOK
if (!ksu_sucompat_non_kp){
return 0;
}
#endif
if (unlikely(!filename_user))
return 0;
@@ -211,7 +192,7 @@ int ksu_handle_execve_sucompat(int *fd, const char __user **filename_user, void
* some cpus dont really have that good speculative execution
* access_ok to substitute set_fs, we check if pointer is accessible
*/
#if LINUX_VERSION_CODE < KERNEL_VERSION(5,0,0)
#if LINUX_VERSION_CODE < KERNEL_VERSION(5, 0, 0)
if (!access_ok(VERIFY_READ, *filename_user, sizeof(path)))
return 0;
#else
@@ -226,24 +207,24 @@ int ksu_handle_execve_sucompat(int *fd, const char __user **filename_user, void
// strncpy_from_user_nofault does this too
path[sizeof(path) - 1] = '\0';
if (likely(memcmp(path, su, sizeof(su))))
return 0;
if (likely(memcmp(path, su, sizeof(su))))
return 0;
if (!ksu_is_allow_uid(current_uid().val))
return 0;
if (!ksu_is_allow_uid(current_uid().val))
return 0;
pr_info("sys_execve su found\n");
*filename_user = ksud_user_path();
pr_info("sys_execve su found\n");
*filename_user = ksud_user_path();
ksu_escape_to_root();
ksu_escape_to_root();
return 0;
return 0;
}
int ksu_handle_devpts(struct inode *inode)
{
#ifndef CONFIG_KSU_KPROBES_HOOK
if (!ksu_sucompat_non_kp) {
if (!ksu_sucompat_hook_state) {
return 0;
}
#endif
@@ -252,10 +233,11 @@ int ksu_handle_devpts(struct inode *inode)
return 0;
}
uid_t uid = current_uid().val;
if (uid % 100000 < 10000) {
return 0;
}
uid_t uid = current_uid().val;
if (uid % 100000 < 10000) {
// not untrusted_app, ignore it
return 0;
}
if (!ksu_is_allow_uid(uid))
return 0;
@@ -264,7 +246,8 @@ int ksu_handle_devpts(struct inode *inode)
#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 1, 0)
struct inode_security_struct *sec = selinux_inode(inode);
#else
struct inode_security_struct *sec = (struct inode_security_struct *)inode->i_security;
struct inode_security_struct *sec =
(struct inode_security_struct *)inode->i_security;
#endif
if (sec) {
sec->sid = ksu_devpts_sid;
@@ -275,6 +258,7 @@ int ksu_handle_devpts(struct inode *inode)
}
#ifdef CONFIG_KSU_KPROBES_HOOK
static int faccessat_handler_pre(struct kprobe *p, struct pt_regs *regs)
{
struct pt_regs *real_regs = PT_REAL_REGS(regs);
@@ -364,8 +348,8 @@ void ksu_sucompat_init()
su_kps[4] = init_kprobe(SYS_FSTATAT64_SYMBOL, newfstatat_handler_pre);
su_kps[5] = init_kprobe("pts_unix98_lookup", pts_unix98_lookup_pre);
#else
ksu_sucompat_non_kp = true;
pr_info("ksu_sucompat_init: hooks enabled: execve/execveat_su, faccessat, stat\n");
ksu_sucompat_hook_state = true;
pr_info("ksu_sucompat init\n");
#endif
}
@@ -377,8 +361,8 @@ void ksu_sucompat_exit()
destroy_kprobe(&su_kps[i]);
}
#else
ksu_sucompat_non_kp = false;
pr_info("ksu_sucompat_exit: hooks disabled: execve/execveat_su, faccessat, stat\n");
ksu_sucompat_hook_state = false;
pr_info("ksu_sucompat exit\n");
#endif
}
@@ -418,4 +402,4 @@ void ksu_susfs_enable_sus_su(void) {
ksu_devpts_hook = true;
susfs_sus_su_working_mode = SUS_SU_WITH_HOOKS;
}
#endif // CONFIG_KSU_SUSFS_SUS_SU
#endif // #ifdef CONFIG_KSU_SUSFS_SUS_SU