linux-kernel - Re: [PATCH 30/44] kdbus: Cleanup kdbus_meta_proc

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Message-ID: <CANq1E4RnbGFjSrg_33Zzsfs+NZv4MeVpbje4O5bMpD2WUJcM-Q@mail.gmail.com>
Date:	Thu, 8 Oct 2015 16:47:48 +0200
From:	David Herrmann <dh.herrmann@...il.com>
To:	Sergei Zviagintsev <sergei@...v.net>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Daniel Mack <daniel@...que.org>,
	David Herrmann <dh.herrmann@...glemail.com>,
	Djalal Harouni <tixxdz@...ndz.org>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 30/44] kdbus: Cleanup kdbus_meta_proc_mask()

Hi

On Thu, Oct 8, 2015 at 1:31 PM, Sergei Zviagintsev <sergei@...v.net> wrote:
>  - Simplify if-statements
>
>    'proc < KDBUS_META_PROC_NORMAL' test only makes sense when we call
>    kdbus_proc_permission(). Include it into 'prv_pid != req_pid' branch,
>    remove redundant assignment of `proc' var and reduce its scope.
>
>  - Drop redundant binary operation
>
>    In 'proc < KDBUS_META_PROC_NORMAL' case we firstly do
>    'wanted &= ~flags' and then 'wanted & flags' in the return statement,
>    which is the same as 'wanted & 0'. Return 0 instead.
>
>  - Cosmetic cleanup of the return statement.
>
> Signed-off-by: Sergei Zviagintsev <sergei@...v.net>
> ---
>  ipc/kdbus/metadata.c | 32 ++++++++++++--------------------
>  1 file changed, 12 insertions(+), 20 deletions(-)
>
> diff --git a/ipc/kdbus/metadata.c b/ipc/kdbus/metadata.c
> index 61215a078359..b8d094d9fb56 100644
> --- a/ipc/kdbus/metadata.c
> +++ b/ipc/kdbus/metadata.c
> @@ -1224,7 +1224,6 @@ static u64 kdbus_meta_proc_mask(struct pid *prv_pid,
>                                 u64 wanted)
>  {
>         struct pid_namespace *prv_ns, *req_ns;
> -       unsigned int proc;
>
>         prv_ns = ns_of_pid(prv_pid);
>         req_ns = ns_of_pid(req_pid);
> @@ -1243,30 +1242,23 @@ static u64 kdbus_meta_proc_mask(struct pid *prv_pid,
>          * provider and requestor are the same. If not, we perform rather
>          * expensive /proc permission checks.
>          */
> -       if (prv_pid == req_pid)
> -               proc = KDBUS_META_PROC_NORMAL;
> -       else
> -               proc = kdbus_proc_permission(req_ns, req_cred, prv_pid);
> -
> -       /* you need /proc access to read standard process attributes */
> -       if (proc < KDBUS_META_PROC_NORMAL)
> -               wanted &= ~(KDBUS_ATTACH_TID_COMM |
> -                           KDBUS_ATTACH_PID_COMM |
> -                           KDBUS_ATTACH_SECLABEL |
> -                           KDBUS_ATTACH_CMDLINE |
> -                           KDBUS_ATTACH_CGROUP |
> -                           KDBUS_ATTACH_AUDIT |
> -                           KDBUS_ATTACH_CAPS |
> -                           KDBUS_ATTACH_EXE);
> +       if (prv_pid != req_pid) {
> +               unsigned int proc = kdbus_proc_permission(req_ns, req_cred,
> +                                                         prv_pid);

Please keep "proc" declared non-local. Also, we don't do direct
assignments of non-static data in declarations.

Thanks
David

> +
> +               /* you need /proc access to read standard process attributes */
> +               if (proc < KDBUS_META_PROC_NORMAL)
> +                       return 0;
> +       }
>
>         /* clear all non-/proc flags */
>         return wanted & (KDBUS_ATTACH_TID_COMM |
>                          KDBUS_ATTACH_PID_COMM |
>                          KDBUS_ATTACH_SECLABEL |
> -                        KDBUS_ATTACH_CMDLINE |
> -                        KDBUS_ATTACH_CGROUP |
> -                        KDBUS_ATTACH_AUDIT |
> -                        KDBUS_ATTACH_CAPS |
> +                        KDBUS_ATTACH_CMDLINE  |
> +                        KDBUS_ATTACH_CGROUP   |
> +                        KDBUS_ATTACH_AUDIT    |
> +                        KDBUS_ATTACH_CAPS     |
>                          KDBUS_ATTACH_EXE);
>  }
>
> --
> 1.8.3.1
>
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