linux-kernel - Re: [PATCH ghak84 v4] audit: purge audit_log

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Date:   Tue, 14 Jul 2020 12:21:45 -0400
From:   Paul Moore <paul@...l-moore.com>
To:     Richard Guy Briggs <rgb@...hat.com>
Cc:     Linux-Audit Mailing List <linux-audit@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux Security Module list 
        <linux-security-module@...r.kernel.org>,
        Eric Paris <eparis@...isplace.org>, john.johansen@...onical.com
Subject: Re: [PATCH ghak84 v4] audit: purge audit_log_string from the
 intra-kernel audit API

On Mon, Jul 13, 2020 at 3:52 PM Richard Guy Briggs <rgb@...hat.com> wrote:
>
> audit_log_string() was inteded to be an internal audit function and
> since there are only two internal uses, remove them.  Purge all external
> uses of it by restructuring code to use an existing audit_log_format()
> or using audit_log_format().
>
> Please see the upstream issue
> https://github.com/linux-audit/audit-kernel/issues/84
>
> Signed-off-by: Richard Guy Briggs <rgb@...hat.com>
> ---
> Passes audit-testsuite.
>
> Changelog:
> v4
> - use double quotes in all replaced audit_log_string() calls
>
> v3
> - fix two warning: non-void function does not return a value in all control paths
>         Reported-by: kernel test robot <lkp@...el.com>
>
> v2
> - restructure to piggyback on existing audit_log_format() calls, checking quoting needs for each.
>
> v1 Vlad Dronov
> - https://github.com/nefigtut/audit-kernel/commit/dbbcba46335a002f44b05874153a85b9cc18aebf
>
>  include/linux/audit.h     |  5 -----
>  kernel/audit.c            |  4 ++--
>  security/apparmor/audit.c | 10 ++++------
>  security/apparmor/file.c  | 25 +++++++------------------
>  security/apparmor/ipc.c   | 46 +++++++++++++++++++++++-----------------------
>  security/apparmor/net.c   | 14 ++++++++------
>  security/lsm_audit.c      |  4 ++--
>  7 files changed, 46 insertions(+), 62 deletions(-)

Thanks for restoring the quotes, just one question below ...

> diff --git a/security/apparmor/ipc.c b/security/apparmor/ipc.c
> index 4ecedffbdd33..fe36d112aad9 100644
> --- a/security/apparmor/ipc.c
> +++ b/security/apparmor/ipc.c
> @@ -20,25 +20,23 @@
>
>  /**
>   * audit_ptrace_mask - convert mask to permission string
> - * @buffer: buffer to write string to (NOT NULL)
>   * @mask: permission mask to convert
> + *
> + * Returns: pointer to static string
>   */
> -static void audit_ptrace_mask(struct audit_buffer *ab, u32 mask)
> +static const char *audit_ptrace_mask(u32 mask)
>  {
>         switch (mask) {
>         case MAY_READ:
> -               audit_log_string(ab, "read");
> -               break;
> +               return "read";
>         case MAY_WRITE:
> -               audit_log_string(ab, "trace");
> -               break;
> +               return "trace";
>         case AA_MAY_BE_READ:
> -               audit_log_string(ab, "readby");
> -               break;
> +               return "readby";
>         case AA_MAY_BE_TRACED:
> -               audit_log_string(ab, "tracedby");
> -               break;
> +               return "tracedby";
>         }
> +       return "";

Are we okay with this returning an empty string ("") in this case?
Should it be a question mark ("?")?

My guess is that userspace parsing should be okay since it still has
quotes, I'm just not sure if we wanted to use a question mark as we do
in other cases where the field value is empty/unknown.

-- 
paul moore
www.paul-moore.com