From mboxrd@z Thu Jan 1 00:00:00 1970 From: Howard McLauchlan Subject: Re: [PATCH] bpf: whitelist syscalls for error injection Date: Fri, 16 Mar 2018 15:55:04 -0700 Message-ID: References: <20180313231627.1247-1-hmclauchlan@fb.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Dominik Brodowski Cc: Andy Lutomirski , Ingo Molnar , LKML , Linux API , Al Viro , Thomas Gleixner , Yonghong Song , "David S . Miller" , Thomas Garnier , kernel-team List-Id: linux-api@vger.kernel.org On 03/13/2018 04:56 PM, Andy Lutomirski wrote: > On Tue, Mar 13, 2018 at 11:16 PM, Howard McLauchlan wrote: >> Error injection is a useful mechanism to fail arbitrary kernel >> functions. However, it is often hard to guarantee an error propagates >> appropriately to user space programs. By injecting into syscalls, we can >> return arbitrary values to user space directly; this increases >> flexibility and robustness in testing, allowing us to test user space >> error paths effectively. > > Temporary NAK IMO. Specifically: > >> diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h >> index a78186d826d7..e8c6d63ace78 100644 >> --- a/include/linux/syscalls.h >> +++ b/include/linux/syscalls.h >> @@ -191,6 +191,8 @@ static inline int is_syscall_trace_event(struct trace_event_call *tp_event) >> >> #define SYSCALL_DEFINE0(sname) \ >> SYSCALL_METADATA(_##sname, 0); \ >> + asmlinkage long sys_##sname(void); \ >> + ALLOW_ERROR_INJECTION(sys_##sname, ERRNO); \ > > sys_xyz() is not just the syscall itself; it's also a helper that's > used for entirely silly reasons by various bits of kernel code for > quite a few syscalls. Fortunately, Dominik has patches to fix that, > and Linus is even considering pulling them for 4.16. This patch will > most likely conflict with the final result of Dominik's series. > > Can you and Dominik coordinate a bit to get this patch or its > equivalent landed on top of Dominik's work? It might make sense for > Dominik to just add this patch to his series so it can land with the > rest of it. Dominik, Ingo, what do you think? > > --Andy > Dominik, This patch applies cleanly on top of your patch series. Is there anything you'd need from me to get this in on top of your work? Howard