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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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11
kernel/core_hook.c
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@@ -559,7 +559,14 @@ static int handler_pre(struct kprobe *p, struct pt_regs *regs)
int option = (int)PT_REGS_PARM1(real_regs);
unsigned long arg2 = (unsigned long)PT_REGS_PARM2(real_regs);
unsigned long arg3 = (unsigned long)PT_REGS_PARM3(real_regs);
unsigned long arg4 = (unsigned long)PT_REGS_PARM4(real_regs);
#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 16, 0)
// PRCTL_SYMBOL is the arch-specificed one, which receive raw pt_regs from syscall
unsigned long arg4 = (unsigned long)PT_REGS_SYSCALL_PARM4(real_regs);
#else
// PRCTL_SYMBOL is the common one, called by C convention in do_syscall_64
// https://elixir.bootlin.com/linux/v4.15.18/source/arch/x86/entry/common.c#L287
unsigned long arg4 = (unsigned long)PT_REGS_CCALL_PARM4(real_regs);
#endif
unsigned long arg5 = (unsigned long)PT_REGS_PARM5(real_regs);
return ksu_handle_prctl(option, arg2, arg3, arg4, arg5);
@@ -579,7 +586,7 @@ static int renameat_handler_pre(struct kprobe *p, struct pt_regs *regs)
struct dentry *new_entry = rd->new_dentry;
#else
struct dentry *old_entry = (struct dentry *)PT_REGS_PARM2(regs);
struct dentry *new_entry = (struct dentry *)PT_REGS_PARM4(regs);
struct dentry *new_entry = (struct dentry *)PT_REGS_CCALL_PARM4(regs);
#endif
return ksu_handle_rename(old_entry, new_entry);