From: Kees Cook <keescook@chromium.org>
To: "Mickaël Salaün" <mic@digikod.net>
Cc: LKML <linux-kernel@vger.kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Andy Lutomirski <luto@amacapital.net>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Casey Schaufler <casey@schaufler-ca.com>,
Daniel Borkmann <daniel@iogearbox.net>,
David Drysdale <drysdale@google.com>,
"David S . Miller" <davem@davemloft.net>,
"Eric W . Biederman" <ebiederm@xmission.com>,
James Morris <james.l.morris@oracle.com>,
Jann Horn <jann@thejh.net>, Jonathan Corbet <corbet@lwn.net>,
Matthew Garrett <mjg59@srcf.ucam.org>,
Michael Kerrisk <mtk.manpages@gmail.com>,
Paul Moore <paul@paul-moore.com>,
Sargun Dhillon <sargun@sargun.me>,
"Serge E . Hallyn" <serge@hallyn.com>,
Shuah Khan <shuah@kernel.org>, Tejun Heo <tj@kernel.org>,
Thomas Graf <tgraf@suug.ch>, Will Drewry <wa>
Subject: Re: [PATCH net-next v6 05/11] seccomp: Split put_seccomp_filter() with put_seccomp()
Date: Tue, 18 Apr 2017 15:23:02 -0700 [thread overview]
Message-ID: <CAGXu5jK3awbLYJTq9keb7oafUxU=_Ec9uMUHNWQH7skEhEg7WQ@mail.gmail.com> (raw)
In-Reply-To: <20170328234650.19695-6-mic@digikod.net>
On Tue, Mar 28, 2017 at 4:46 PM, Mickaël Salaün <mic@digikod.net> wrote:
> The semantic is unchanged. This will be useful for the Landlock
> integration with seccomp (next commit).
>
> Signed-off-by: Mickaël Salaün <mic@digikod.net>
> Cc: Kees Cook <keescook@chromium.org>
> Cc: Andy Lutomirski <luto@amacapital.net>
> Cc: Will Drewry <wad@chromium.org>
> ---
> include/linux/seccomp.h | 4 ++--
> kernel/fork.c | 2 +-
> kernel/seccomp.c | 18 +++++++++++++-----
> 3 files changed, 16 insertions(+), 8 deletions(-)
>
> diff --git a/include/linux/seccomp.h b/include/linux/seccomp.h
> index ecc296c137cd..e25aee2cdfc0 100644
> --- a/include/linux/seccomp.h
> +++ b/include/linux/seccomp.h
> @@ -77,10 +77,10 @@ static inline int seccomp_mode(struct seccomp *s)
> #endif /* CONFIG_SECCOMP */
>
> #ifdef CONFIG_SECCOMP_FILTER
> -extern void put_seccomp_filter(struct task_struct *tsk);
> +extern void put_seccomp(struct task_struct *tsk);
> extern void get_seccomp_filter(struct task_struct *tsk);
> #else /* CONFIG_SECCOMP_FILTER */
> -static inline void put_seccomp_filter(struct task_struct *tsk)
> +static inline void put_seccomp(struct task_struct *tsk)
> {
> return;
> }
> diff --git a/kernel/fork.c b/kernel/fork.c
> index 6c463c80e93d..a27d8e67ce33 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -363,7 +363,7 @@ void free_task(struct task_struct *tsk)
> #endif
> rt_mutex_debug_task_free(tsk);
> ftrace_graph_exit_task(tsk);
> - put_seccomp_filter(tsk);
> + put_seccomp(tsk);
> arch_release_task_struct(tsk);
> if (tsk->flags & PF_KTHREAD)
> free_kthread_struct(tsk);
> diff --git a/kernel/seccomp.c b/kernel/seccomp.c
> index 65f61077ad50..326f79e32127 100644
> --- a/kernel/seccomp.c
> +++ b/kernel/seccomp.c
> @@ -64,6 +64,8 @@ struct seccomp_filter {
> /* Limit any path through the tree to 256KB worth of instructions. */
> #define MAX_INSNS_PER_PATH ((1 << 18) / sizeof(struct sock_filter))
>
> +static void put_seccomp_filter(struct seccomp_filter *filter);
Can this be reorganized easily to avoid a forward-declaration?
> +
> /*
> * Endianness is explicitly ignored and left for BPF program authors to manage
> * as per the specific architecture.
> @@ -314,7 +316,7 @@ static inline void seccomp_sync_threads(void)
> * current's path will hold a reference. (This also
> * allows a put before the assignment.)
> */
> - put_seccomp_filter(thread);
> + put_seccomp_filter(thread->seccomp.filter);
> smp_store_release(&thread->seccomp.filter,
> caller->seccomp.filter);
>
> @@ -476,10 +478,11 @@ static inline void seccomp_filter_free(struct seccomp_filter *filter)
> }
> }
>
> -/* put_seccomp_filter - decrements the ref count of tsk->seccomp.filter */
> -void put_seccomp_filter(struct task_struct *tsk)
> +/* put_seccomp_filter - decrements the ref count of a filter */
> +static void put_seccomp_filter(struct seccomp_filter *filter)
> {
> - struct seccomp_filter *orig = tsk->seccomp.filter;
> + struct seccomp_filter *orig = filter;
> +
> /* Clean up single-reference branches iteratively. */
> while (orig && atomic_dec_and_test(&orig->usage)) {
> struct seccomp_filter *freeme = orig;
> @@ -488,6 +491,11 @@ void put_seccomp_filter(struct task_struct *tsk)
> }
> }
>
> +void put_seccomp(struct task_struct *tsk)
> +{
> + put_seccomp_filter(tsk->seccomp.filter);
> +}
> +
> static void seccomp_init_siginfo(siginfo_t *info, int syscall, int reason)
> {
> memset(info, 0, sizeof(*info));
> @@ -914,7 +922,7 @@ long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
> if (copy_to_user(data, fprog->filter, bpf_classic_proglen(fprog)))
> ret = -EFAULT;
>
> - put_seccomp_filter(task);
> + put_seccomp_filter(task->seccomp.filter);
> return ret;
I don't like that the arguments to get_seccomp_filter() and
put_seccomp_filter() are now different. I think they should match for
readability.
-Kees
--
Kees Cook
Pixel Security
next prev parent reply other threads:[~2017-04-18 22:23 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-28 23:46 [PATCH net-next v6 00/11] Landlock LSM: Toward unprivileged sandboxing Mickaël Salaün
[not found] ` <20170328234650.19695-1-mic-WFhQfpSGs3bR7s880joybQ@public.gmane.org>
2017-03-28 23:46 ` [PATCH net-next v6 01/11] bpf: Add eBPF program subtype and is_valid_subtype() verifier Mickaël Salaün
[not found] ` <20170328234650.19695-2-mic-WFhQfpSGs3bR7s880joybQ@public.gmane.org>
2017-03-29 13:48 ` kbuild test robot
2017-04-18 21:48 ` Kees Cook
2017-03-28 23:46 ` [PATCH net-next v6 02/11] bpf,landlock: Define an eBPF program type for Landlock Mickaël Salaün
2017-04-16 21:57 ` Mickaël Salaün
[not found] ` <20170328234650.19695-3-mic-WFhQfpSGs3bR7s880joybQ@public.gmane.org>
2017-04-18 21:58 ` Kees Cook
2017-03-28 23:46 ` [PATCH net-next v6 03/11] bpf: Define handle_fs and add a new helper bpf_handle_fs_get_mode() Mickaël Salaün
2017-03-28 23:46 ` [PATCH net-next v6 04/11] landlock: Add LSM hooks related to filesystem Mickaël Salaün
2017-03-29 15:18 ` kbuild test robot
[not found] ` <20170328234650.19695-5-mic-WFhQfpSGs3bR7s880joybQ@public.gmane.org>
2017-04-18 22:17 ` Kees Cook
2017-04-18 22:44 ` Mickaël Salaün
[not found] ` <9a69055a-b4cf-00b0-da5e-2e45ff88059c-WFhQfpSGs3bR7s880joybQ@public.gmane.org>
2017-04-18 23:16 ` Casey Schaufler
2017-04-18 23:40 ` Kees Cook
2017-04-19 22:03 ` Mickaël Salaün
[not found] ` <35272f2b-ec5f-d032-ae2e-9fc0b4c0e2e3-WFhQfpSGs3bR7s880joybQ@public.gmane.org>
2017-04-19 23:58 ` [kernel-hardening] " Casey Schaufler
2017-04-20 1:48 ` Kees Cook
2017-04-18 23:39 ` Kees Cook
2017-03-28 23:46 ` [PATCH net-next v6 05/11] seccomp: Split put_seccomp_filter() with put_seccomp() Mickaël Salaün
2017-04-18 22:23 ` Kees Cook [this message]
2017-04-18 22:47 ` Mickaël Salaün
2017-04-19 22:18 ` Mickaël Salaün
[not found] ` <96024881-1bcc-33af-6285-d9a904de963e-WFhQfpSGs3bR7s880joybQ@public.gmane.org>
2017-04-20 1:54 ` Kees Cook
2017-03-28 23:46 ` [PATCH net-next v6 06/11] seccomp,landlock: Handle Landlock events per process hierarchy Mickaël Salaün
2017-03-29 10:35 ` Djalal Harouni
2017-03-31 21:15 ` Mickaël Salaün
2017-04-18 22:54 ` [kernel-hardening] " Kees Cook
[not found] ` <20170328234650.19695-7-mic-WFhQfpSGs3bR7s880joybQ@public.gmane.org>
2017-04-18 22:53 ` Kees Cook
2017-04-18 23:24 ` Mickaël Salaün
[not found] ` <a3c71579-4238-0967-b61d-522859f740aa-WFhQfpSGs3bR7s880joybQ@public.gmane.org>
2017-04-18 23:48 ` Kees Cook
2017-03-28 23:46 ` [PATCH net-next v6 07/11] landlock: Add ptrace restrictions Mickaël Salaün
[not found] ` <20170328234650.19695-8-mic-WFhQfpSGs3bR7s880joybQ@public.gmane.org>
2017-04-10 6:48 ` [kernel-hardening] " Djalal Harouni
2017-04-11 7:19 ` Mickaël Salaün
2017-03-28 23:46 ` [PATCH net-next v6 08/11] bpf: Add a Landlock sandbox example Mickaël Salaün
2017-04-18 23:06 ` Kees Cook
2017-04-18 23:35 ` Mickaël Salaün
2017-03-28 23:46 ` [PATCH net-next v6 09/11] seccomp: Enhance test_harness with an assert step mechanism Mickaël Salaün
[not found] ` <20170328234650.19695-10-mic-WFhQfpSGs3bR7s880joybQ@public.gmane.org>
2017-04-19 0:02 ` Kees Cook
2017-04-19 21:51 ` Mickaël Salaün
[not found] ` <94ac6ddc-eaac-8548-f83f-826ddf05ac69-WFhQfpSGs3bR7s880joybQ@public.gmane.org>
2017-04-19 22:02 ` Kees Cook
2017-04-19 22:05 ` Mickaël Salaün
2017-04-20 1:50 ` Kees Cook
2017-03-28 23:46 ` [PATCH net-next v6 10/11] bpf,landlock: Add tests for Landlock Mickaël Salaün
2017-04-18 23:16 ` Kees Cook
2017-04-18 23:53 ` Mickaël Salaün
2017-04-18 23:59 ` Kees Cook
2017-03-28 23:46 ` [PATCH net-next v6 11/11] landlock: Add user and kernel documentation " Mickaël Salaün
2017-03-29 15:58 ` kbuild test robot
2017-04-18 23:26 ` [PATCH net-next v6 00/11] Landlock LSM: Toward unprivileged sandboxing Kees Cook
2017-04-19 0:12 ` Mickaël Salaün
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