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Distinguish different PT_REGS_PARM4 under x86 (#711)

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1. `PT_REGS_CCALL_PARM4` 表示存放C调用约定的第4个参数的寄存器
2. `PT_REGS_SYSCALL_PARM4` 表示存放linux syscall调用约定的第4个参数的寄存器
3. 将原有 `PT_REGS_PARM4` 改为上述之一
4. 将原有 `ksu_handle_execveat_ksud` 和 `ksu_handle_execveat_sucompat` 可能被
kprobe 传递错误实参、且不使用的形参标记为 never_used 并传递 `NULL`
5. 为 `ksu_handle_execveat_ksud` 提供正确的 argv 参数用以在 x86 下也能正确识别 `init
second_stage`

---------

Co-authored-by: weishu <twsxtd@gmail.com>
This commit is contained in:
4qwerty7
2023-07-06 09:01:35 +08:00
committed by GitHub
parent 2c0a9cd64c
commit f4d2b0feab
5 changed files with 41 additions and 41 deletions
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43
kernel/ksud.c
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@@ -138,8 +138,9 @@ static int __maybe_unused count(struct user_arg_ptr argv, int max)
return i;
}
// 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_ksud(int *fd, struct filename **filename_ptr,
void *argv, void *envp, int *flags)
struct user_arg_ptr *argv, void *__never_use_envp, int *__never_use_flags)
{
#ifndef CONFIG_KPROBES
if (!ksu_execveat_hook) {
@@ -163,13 +164,11 @@ int ksu_handle_execveat_ksud(int *fd, struct filename **filename_ptr,
if (unlikely(!memcmp(filename->name, system_bin_init,
sizeof(system_bin_init) - 1))) {
#ifdef __aarch64__
// /system/bin/init executed
struct user_arg_ptr *ptr = (struct user_arg_ptr*) argv;
int argc = count(*ptr, MAX_ARG_STRINGS);
int argc = count(*argv, MAX_ARG_STRINGS);
pr_info("/system/bin/init argc: %d\n", argc);
if (argc > 1 && !init_second_stage_executed) {
const char __user *p = get_user_arg_ptr(*ptr, 1);
const char __user *p = get_user_arg_ptr(*argv, 1);
if (p && !IS_ERR(p)) {
char first_arg[16];
ksu_strncpy_from_user_nofault(first_arg, p, sizeof(first_arg));
@@ -184,20 +183,6 @@ int ksu_handle_execveat_ksud(int *fd, struct filename **filename_ptr,
pr_err("/system/bin/init parse args err!\n");
}
}
#else
// The argument parse is incorrect becuase of the struct user_arg_ptr has 16bytes
// and it is passed by value(not pointer), in arm64, it is correct becuase the register
// is just arranged correct accidentally, but is not correct in x86_64
// i have no device to test, so revert it for x86_64
static int init_count = 0;
if (++init_count == 2) {
// 1: /system/bin/init selinux_setup
// 2: /system/bin/init second_stage
pr_info("/system/bin/init second_stage executed\n");
apply_kernelsu_rules();
ksu_android_ns_fs_check();
}
#endif
}
if (unlikely(first_app_process &&
@@ -394,11 +379,19 @@ static int execve_handler_pre(struct kprobe *p, struct pt_regs *regs)
int *fd = (int *)&PT_REGS_PARM1(regs);
struct filename **filename_ptr =
(struct filename **)&PT_REGS_PARM2(regs);
void *argv = (void *)&PT_REGS_PARM3(regs);
void *envp = (void *)&PT_REGS_PARM4(regs);
int *flags = (int *)&PT_REGS_PARM5(regs);
struct user_arg_ptr argv;
#ifdef CONFIG_COMPAT
argv.is_compat = PT_REGS_PARM3(regs);
if (unlikely(argv.is_compat)) {
argv.ptr.compat = PT_REGS_CCALL_PARM4(regs);
} else {
argv.ptr.native = PT_REGS_CCALL_PARM4(regs);
}
#else
argv.ptr.native = PT_REGS_PARM3(regs);
#endif
return ksu_handle_execveat_ksud(fd, filename_ptr, argv, envp, flags);
return ksu_handle_execveat_ksud(fd, filename_ptr, &argv, NULL, NULL);
}
static int read_handler_pre(struct kprobe *p, struct pt_regs *regs)
@@ -406,7 +399,7 @@ static int read_handler_pre(struct kprobe *p, struct pt_regs *regs)
struct file **file_ptr = (struct file **)&PT_REGS_PARM1(regs);
char __user **buf_ptr = (char **)&PT_REGS_PARM2(regs);
size_t *count_ptr = (size_t *)&PT_REGS_PARM3(regs);
loff_t **pos_ptr = (loff_t **)&PT_REGS_PARM4(regs);
loff_t **pos_ptr = (loff_t **)&PT_REGS_CCALL_PARM4(regs);
return ksu_handle_vfs_read(file_ptr, buf_ptr, count_ptr, pos_ptr);
}
@@ -416,7 +409,7 @@ static int input_handle_event_handler_pre(struct kprobe *p,
{
unsigned int *type = (unsigned int *)&PT_REGS_PARM2(regs);
unsigned int *code = (unsigned int *)&PT_REGS_PARM3(regs);
int *value = (int *)&PT_REGS_PARM4(regs);
int *value = (int *)&PT_REGS_CCALL_PARM4(regs);
return ksu_handle_input_handle_event(type, code, value);
}