[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <202009101625.0E3B6242@keescook>
Date: Thu, 10 Sep 2020 16:33:38 -0700
From: Kees Cook <keescook@...omium.org>
To: kernel-hardening@...ts.openwall.com
Cc: John Wood <john.wood@....com>, Matthew Wilcox <willy@...radead.org>,
Jonathan Corbet <corbet@....net>,
Alexander Viro <viro@...iv.linux.org.uk>,
Ingo Molnar <mingo@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Juri Lelli <juri.lelli@...hat.com>,
Vincent Guittot <vincent.guittot@...aro.org>,
Dietmar Eggemann <dietmar.eggemann@....com>,
Steven Rostedt <rostedt@...dmis.org>,
Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
Luis Chamberlain <mcgrof@...nel.org>,
Iurii Zaikin <yzaikin@...gle.com>, James Morris <jmorris@...ei.org>,
"Serge E. Hallyn" <serge@...lyn.com>, linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
linux-security-module@...r.kernel.org
Subject: Re: [RFC PATCH 3/6] security/fbfam: Use the api to manage statistics
On Thu, Sep 10, 2020 at 01:21:04PM -0700, Kees Cook wrote:
> From: John Wood <john.wood@....com>
>
> Use the previous defined api to manage statistics calling it accordingly
> when a task forks, calls execve or exits.
>
> Signed-off-by: John Wood <john.wood@....com>
> ---
> fs/exec.c | 2 ++
> kernel/exit.c | 2 ++
> kernel/fork.c | 4 ++++
> 3 files changed, 8 insertions(+)
>
> diff --git a/fs/exec.c b/fs/exec.c
> index a91003e28eaa..b30118674d32 100644
> --- a/fs/exec.c
> +++ b/fs/exec.c
> @@ -71,6 +71,7 @@
> #include "internal.h"
>
> #include <trace/events/sched.h>
> +#include <fbfam/fbfam.h>
>
> static int bprm_creds_from_file(struct linux_binprm *bprm);
>
> @@ -1940,6 +1941,7 @@ static int bprm_execve(struct linux_binprm *bprm,
> task_numa_free(current, false);
> if (displaced)
> put_files_struct(displaced);
> + fbfam_execve();
As mentioned in the other emails, I think this could trivially be
converted into an LSM: all the hooks are available AFAICT. If you only
want to introspect execve _happening_, you can use bprm_creds_for_exec
which is called a few lines above. Otherwise, my prior suggestion ("the
exec has happened" hook via brpm_cred_committing, etc).
> return retval;
>
> out:
> diff --git a/kernel/exit.c b/kernel/exit.c
> index 733e80f334e7..39a6139dcf31 100644
> --- a/kernel/exit.c
> +++ b/kernel/exit.c
> @@ -67,6 +67,7 @@
> #include <linux/uaccess.h>
> #include <asm/unistd.h>
> #include <asm/mmu_context.h>
> +#include <fbfam/fbfam.h>
>
> static void __unhash_process(struct task_struct *p, bool group_dead)
> {
> @@ -852,6 +853,7 @@ void __noreturn do_exit(long code)
> __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied);
> exit_rcu();
> exit_tasks_rcu_finish();
> + fbfam_exit();
>
> lockdep_free_task(tsk);
> do_task_dead();
The place for this would be put_task_struct, and the LSM hook is
task_free. :) (The only caveat with task_free hook is that it may be
called in non-process context due to being freed during RCU, etc. In
practice, this is unlikely to cause problems.)
> diff --git a/kernel/fork.c b/kernel/fork.c
> index 49677d668de4..c933838450a8 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -107,6 +107,8 @@
> #define CREATE_TRACE_POINTS
> #include <trace/events/task.h>
>
> +#include <fbfam/fbfam.h>
> +
> /*
> * Minimum number of threads to boot the kernel
> */
> @@ -941,6 +943,8 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
> #ifdef CONFIG_MEMCG
> tsk->active_memcg = NULL;
> #endif
> +
> + fbfam_fork(tsk);
> return tsk;
Since you don't need "orig", this is also trivially an LSM hook.
dup_task_struct() is called by copy_process(), which will also call the
task_alloc LSM hook later on.
>
> free_stack:
> --
> 2.25.1
>
--
Kees Cook
Powered by blists - more mailing lists
Confused about mailing lists and their use?
Read about mailing lists on Wikipedia
and check out these
guidelines on proper formatting of your messages.
