Re: [PATCH v1 2/2] signal: add procfd_signal() syscall

From: kbuild test robot <lkp@intel.com>
To: Christian Brauner <christian@brauner.io>
Cc: kbuild-all@01.org, ebiederm@xmission.com,
	linux-kernel@vger.kernel.org, serge@hallyn.com, jannh@google.com,
	luto@kernel.org, akpm@linux-foundation.org, oleg@redhat.com,
	cyphar@cyphar.com, viro@zeniv.linux.org.uk,
	linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org,
	dancol@google.com, timmurray@google.com,
	linux-man@vger.kernel.org,
	Christian Brauner <christian@brauner.io>,
	Kees Cook <keescook@chromium.org>
Subject: Re: [PATCH v1 2/2] signal: add procfd_signal() syscall
Date: Tue, 20 Nov 2018 07:37:58 +0800	[thread overview]
Message-ID: <201811200755.avfmktKQ%fengguang.wu@intel.com> (raw)
In-Reply-To: <20181119103241.5229-3-christian@brauner.io>

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Hi Christian,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on linus/master]
[also build test ERROR on v4.20-rc3]
[cannot apply to next-20181119]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Christian-Brauner/proc-allow-signaling-processes-via-file-descriptors/20181120-063836
config: riscv-tinyconfig (attached as .config)
compiler: riscv64-linux-gcc (GCC) 8.1.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        GCC_VERSION=8.1.0 make.cross ARCH=riscv 

All errors (new ones prefixed by >>):

   kernel/signal.c: In function '__do_sys_procfd_signal':
>> kernel/signal.c:3341:7: error: implicit declaration of function 'proc_is_procfd'; did you mean 'clockid_to_fd'? [-Werror=implicit-function-declaration]
     if (!proc_is_procfd(f.file))
          ^~~~~~~~~~~~~~
          clockid_to_fd
   cc1: some warnings being treated as errors

vim +3341 kernel/signal.c

  3314	
  3315	/**
  3316	 *  sys_procfd_signal - send a signal to a process through a process file
  3317	 *                      descriptor
  3318	 *  @fd: the file descriptor of the process
  3319	 *  @sig: signal to be sent
  3320	 *  @info: the signal info
  3321	 *  @flags: future flags to be passed
  3322	 */
  3323	SYSCALL_DEFINE4(procfd_signal, int, fd, int, sig, siginfo_t __user *, info,
  3324			int, flags)
  3325	{
  3326		int ret;
  3327		struct pid *pid;
  3328		kernel_siginfo_t kinfo;
  3329		struct fd f;
  3330	
  3331		/* Enforce flags be set to 0 until we add an extension. */
  3332		if (flags)
  3333			return -EINVAL;
  3334	
  3335		f = fdget_raw(fd);
  3336		if (!f.file)
  3337			return -EBADF;
  3338	
  3339		ret = -EINVAL;
  3340		/* Is this a process file descriptor? */
> 3341		if (!proc_is_procfd(f.file))
  3342			goto err;
  3343	
  3344		pid = f.file->private_data;
  3345		if (!pid)
  3346			goto err;
  3347	
  3348		if (info) {
  3349			ret = __copy_siginfo_from_user(sig, &kinfo, info);
  3350			if (unlikely(ret))
  3351				goto err;
  3352			/*
  3353			 * Not even root can pretend to send signals from the kernel.
  3354			 * Nor can they impersonate a kill()/tgkill(), which adds
  3355			 * source info.
  3356			 */
  3357			ret = -EPERM;
  3358			if ((kinfo.si_code >= 0 || kinfo.si_code == SI_TKILL) &&
  3359			    (task_pid(current) != pid))
  3360				goto err;
  3361		} else {
  3362			prepare_kill_siginfo(sig, &kinfo);
  3363		}
  3364	
  3365		ret = kill_pid_info(sig, &kinfo, pid);
  3366	
  3367	err:
  3368		fdput(f);
  3369		return ret;
  3370	}
  3371	

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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