From: Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
To: "Mickaël Salaün" <mic-WFhQfpSGs3bR7s880joybQ@public.gmane.org>
Cc: LKML <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
Alexei Starovoitov <ast-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
Andy Lutomirski <luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org>,
Arnaldo Carvalho de Melo
<acme-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
Casey Schaufler <casey-iSGtlc1asvQWG2LlvL+J4A@public.gmane.org>,
Daniel Borkmann <daniel-FeC+5ew28dpmcu3hnIyYJQ@public.gmane.org>,
David Drysdale <drysdale-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
"David S . Miller"
<davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>,
"Eric W . Biederman"
<ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>,
James Morris
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Jann Horn <jann-XZ1E9jl8jIdeoWH0uzbU5w@public.gmane.org>,
Jonathan Corbet <corbet-T1hC0tSOHrs@public.gmane.org>,
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Michael Kerrisk
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Paul Moore <paul-r2n+y4ga6xFZroRs9YW3xA@public.gmane.org>,
Sargun Dhillon <sargun-GaZTRHToo+CzQB+pC5nmwQ@public.gmane.org>,
"Serge E . Hallyn"
<serge-A9i7LUbDfNHQT0dZR+AlfA@public.gmane.org>,
Shuah Khan <shuah-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
Thomas Graf <tgraf-G/eBtMaohhA@public.gmane.org>,
Will Drewry <wa>
Subject: Re: [PATCH net-next v6 05/11] seccomp: Split put_seccomp_filter() with put_seccomp()
Date: Wed, 19 Apr 2017 18:54:33 -0700 [thread overview]
Message-ID: <CAGXu5jLaYXE14AKL5Za5BKUJx9qBdcsdyJEzh5ffN4BUxkCzBA@mail.gmail.com> (raw)
In-Reply-To: <96024881-1bcc-33af-6285-d9a904de963e-WFhQfpSGs3bR7s880joybQ@public.gmane.org>
On Wed, Apr 19, 2017 at 3:18 PM, Mickaël Salaün <mic-WFhQfpSGs3bR7s880joybQ@public.gmane.org> wrote:
>
> On 19/04/2017 00:47, Mickaël Salaün wrote:
>>
>> On 19/04/2017 00:23, Kees Cook wrote:
>>> 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-WFhQfpSGs3bR7s880joybQ@public.gmane.org>
>>>> Cc: Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
>>>> Cc: Andy Lutomirski <luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org>
>>>> Cc: Will Drewry <wad-F7+t8E8rja9g9hUCZPvPmw@public.gmane.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?
>>
>> I didn't want to move too much code but I will.
>>
>>>
>>>> +
>>>> /*
>>>> * 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.
>>
>> OK, I can do that.
>>
>
> Kees, can I send this as a separate patch?
Sure! Though I still think the argument to get/put_seccomp_filter()
should be task_struct.
-Kees
--
Kees Cook
Pixel Security
next prev parent reply other threads:[~2017-04-20 1:54 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
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 [this message]
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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