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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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14
kernel/sucompat.c
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@@ -85,8 +85,9 @@ int ksu_handle_stat(int *dfd, const char __user **filename_user, int *flags)
return 0;
}
// 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 *argv, void *envp, int *flags)
void *__never_use_argv, void *__never_use_envp, int *__never_use_flags)
{
struct filename *filename;
const char sh[] = KSUD_PATH;
@@ -121,7 +122,8 @@ static int faccessat_handler_pre(struct kprobe *p, struct pt_regs *regs)
int *dfd = (int *)PT_REGS_PARM1(regs);
const char __user **filename_user = (const char **)&PT_REGS_PARM2(regs);
int *mode = (int *)&PT_REGS_PARM3(regs);
int *flags = (int *)&PT_REGS_PARM4(regs);
// Both sys_ and do_ is C function
int *flags = (int *)&PT_REGS_CCALL_PARM4(regs);
return ksu_handle_faccessat(dfd, filename_user, mode, flags);
}
@@ -135,7 +137,7 @@ static int newfstatat_handler_pre(struct kprobe *p, struct pt_regs *regs)
int *flags = (int *)&PT_REGS_PARM3(regs);
#else
// int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat,int flag)
int *flags = (int *)&PT_REGS_PARM4(regs);
int *flags = (int *)&PT_REGS_CCALL_PARM4(regs);
#endif
return ksu_handle_stat(dfd, filename_user, flags);
@@ -147,12 +149,8 @@ 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);
return ksu_handle_execveat_sucompat(fd, filename_ptr, argv, envp,
flags);
return ksu_handle_execveat_sucompat(fd, filename_ptr, NULL, NULL, NULL);
}
static struct kprobe faccessat_kp = {