Messages in this thread | | | Date | Wed, 3 Apr 2024 16:49:10 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCHv2 1/3] uprobe: Add uretprobe syscall to speed up return probe |
| |
Again, I leave this to you and Jiri, but
On 04/03, Masami Hiramatsu wrote: > > On Wed, 3 Apr 2024 11:47:41 +0200 > > > set in the user function, what happen if the user function directly > > > calls this syscall? (maybe it consumes shadow stack?) > > > > the process should receive SIGILL if there's no pending uretprobe for > > the current task, or it will trigger uretprobe if there's one pending > > No, that is too aggressive and not safe. Since the syscall is exposed to > user program, it should return appropriate error code instead of SIGILL.
..
> Since the syscall is always exposed to the user program, it should > - Do nothing and return an error unless it is properly called. > - check the prerequisites for operation strictly.
We have sys_munmap(). should it check if the caller is going to unmap the code region which contains regs->ip and do nothing?
I don't think it should. Userspace should blame itself, SIGSEGV is not "too aggressive" in this case.
> I concern that new system calls introduce vulnerabilities.
Yes, we need to ensure that sys_uretprobe() can only damage the malicious caller and nothing else.
Oleg.
| |