From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752549AbcGRUX0 (ORCPT ); Mon, 18 Jul 2016 16:23:26 -0400 Received: from h2.hallyn.com ([78.46.35.8]:36288 "EHLO h2.hallyn.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752497AbcGRUXW (ORCPT ); Mon, 18 Jul 2016 16:23:22 -0400 Date: Mon, 18 Jul 2016 15:23:20 -0500 From: "Serge E. Hallyn" To: John Stultz Cc: lkml , Kees Cook , "Serge E. Hallyn" , Andrew Morton , Thomas Gleixner , Arjan van de Ven , Oren Laadan , Ruchi Kandoi , Rom Lemarchand , Todd Kjos , Colin Cross , Nick Kralevich , Dmitry Shmidt , Elliott Hughes , Android Kernel Team , linux-security-module@vger.kernel.org, selinux@tycho.nsa.gov Subject: Re: [RFC][PATCH 2/2 v3] security: Add task_settimerslack/task_gettimerslack LSM hook Message-ID: <20160718202320.GB24233@mail.hallyn.com> References: <1468872671-9002-1-git-send-email-john.stultz@linaro.org> <1468872671-9002-2-git-send-email-john.stultz@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1468872671-9002-2-git-send-email-john.stultz@linaro.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Quoting John Stultz (john.stultz@linaro.org): > As requested, this patch implements a task_settimerslack and > task_gettimerslack LSM hooks so that the /proc//timerslack_ns > interface can have finer grained security policies applied to it. > > I've kept the CAP_SYS_NICE check in the timerslack_ns_write/show > functions, as hiding it in the LSM hook seems too opaque, and doesn't > seem like a widely enough adopted practice. > > Don't really know what I'm doing here, so close review would be > appreciated! > > Cc: Kees Cook > Cc: "Serge E. Hallyn" Acked-by: Serge Hallyn > Cc: Andrew Morton > Cc: Thomas Gleixner > CC: Arjan van de Ven > Cc: Oren Laadan > Cc: Ruchi Kandoi > Cc: Rom Lemarchand > Cc: Todd Kjos > Cc: Colin Cross > Cc: Nick Kralevich > Cc: Dmitry Shmidt > Cc: Elliott Hughes > Cc: Android Kernel Team > Cc: linux-security-module@vger.kernel.org > Cc: selinux@tycho.nsa.gov > Signed-off-by: John Stultz > --- > v2: > * Initial swing at adding settimerslack LSM hook > v3: > * Fix current/p switchup bug noted by NickK > * Add gettimerslack hook suggested by NickK > > fs/proc/base.c | 10 ++++++++++ > include/linux/lsm_hooks.h | 13 +++++++++++++ > include/linux/security.h | 12 ++++++++++++ > security/security.c | 14 ++++++++++++++ > security/selinux/hooks.c | 12 ++++++++++++ > 5 files changed, 61 insertions(+) > > diff --git a/fs/proc/base.c b/fs/proc/base.c > index c94abae..cc66aa8 100644 > --- a/fs/proc/base.c > +++ b/fs/proc/base.c > @@ -2286,6 +2286,12 @@ static ssize_t timerslack_ns_write(struct file *file, const char __user *buf, > goto out; > } > > + err = security_task_settimerslack(p, slack_ns); > + if (err) { > + count = err; > + goto out; > + } > + > task_lock(p); > if (slack_ns == 0) > p->timer_slack_ns = p->default_timer_slack_ns; > @@ -2314,6 +2320,10 @@ static int timerslack_ns_show(struct seq_file *m, void *v) > goto out; > } > > + ret = security_task_gettimerslack(p); > + if (ret) > + goto out; > + > task_lock(p); > seq_printf(m, "%llu\n", p->timer_slack_ns); > task_unlock(p); > diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h > index 7ae3976..290483e 100644 > --- a/include/linux/lsm_hooks.h > +++ b/include/linux/lsm_hooks.h > @@ -627,6 +627,15 @@ > * Check permission before moving memory owned by process @p. > * @p contains the task_struct for process. > * Return 0 if permission is granted. > + * @task_settimerslack: > + * Check permission before setting timerslack value of @p to @slack. > + * @p contains the task_struct of a process. > + * @slack contains the new slack value. > + * Return 0 if permission is granted. > + * @task_gettimerslack: > + * Check permission before returning the timerslack value of @p. > + * @p contains the task_struct of a process. > + * Return 0 if permission is granted. > * @task_kill: > * Check permission before sending signal @sig to @p. @info can be NULL, > * the constant 1, or a pointer to a siginfo structure. If @info is 1 or > @@ -1473,6 +1482,8 @@ union security_list_options { > int (*task_setscheduler)(struct task_struct *p); > int (*task_getscheduler)(struct task_struct *p); > int (*task_movememory)(struct task_struct *p); > + int (*task_settimerslack)(struct task_struct *p, u64 slack); > + int (*task_gettimerslack)(struct task_struct *p); > int (*task_kill)(struct task_struct *p, struct siginfo *info, > int sig, u32 secid); > int (*task_wait)(struct task_struct *p); > @@ -1732,6 +1743,8 @@ struct security_hook_heads { > struct list_head task_setscheduler; > struct list_head task_getscheduler; > struct list_head task_movememory; > + struct list_head task_settimerslack; > + struct list_head task_gettimerslack; > struct list_head task_kill; > struct list_head task_wait; > struct list_head task_prctl; > diff --git a/include/linux/security.h b/include/linux/security.h > index 14df373..ab70f47 100644 > --- a/include/linux/security.h > +++ b/include/linux/security.h > @@ -325,6 +325,8 @@ int security_task_setrlimit(struct task_struct *p, unsigned int resource, > int security_task_setscheduler(struct task_struct *p); > int security_task_getscheduler(struct task_struct *p); > int security_task_movememory(struct task_struct *p); > +int security_task_settimerslack(struct task_struct *p, u64 slack); > +int security_task_gettimerslack(struct task_struct *p); > int security_task_kill(struct task_struct *p, struct siginfo *info, > int sig, u32 secid); > int security_task_wait(struct task_struct *p); > @@ -950,6 +952,16 @@ static inline int security_task_movememory(struct task_struct *p) > return 0; > } > > +static inline int security_task_settimerslack(struct task_struct *p, u64 slack) > +{ > + return 0; > +} > + > +static inline int security_task_gettimerslack(struct task_struct *p) > +{ > + return 0; > +} > + > static inline int security_task_kill(struct task_struct *p, > struct siginfo *info, int sig, > u32 secid) > diff --git a/security/security.c b/security/security.c > index 7095693..4ced236 100644 > --- a/security/security.c > +++ b/security/security.c > @@ -977,6 +977,16 @@ int security_task_movememory(struct task_struct *p) > return call_int_hook(task_movememory, 0, p); > } > > +int security_task_settimerslack(struct task_struct *p, u64 slack) > +{ > + return call_int_hook(task_settimerslack, 0, p, slack); > +} > + > +int security_task_gettimerslack(struct task_struct *p) > +{ > + return call_int_hook(task_gettimerslack, 0, p); > +} > + > int security_task_kill(struct task_struct *p, struct siginfo *info, > int sig, u32 secid) > { > @@ -1720,6 +1730,10 @@ struct security_hook_heads security_hook_heads = { > LIST_HEAD_INIT(security_hook_heads.task_getscheduler), > .task_movememory = > LIST_HEAD_INIT(security_hook_heads.task_movememory), > + .task_settimerslack = > + LIST_HEAD_INIT(security_hook_heads.task_settimerslack), > + .task_gettimerslack = > + LIST_HEAD_INIT(security_hook_heads.task_gettimerslack), > .task_kill = LIST_HEAD_INIT(security_hook_heads.task_kill), > .task_wait = LIST_HEAD_INIT(security_hook_heads.task_wait), > .task_prctl = LIST_HEAD_INIT(security_hook_heads.task_prctl), > diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c > index a86d537..aac9599 100644 > --- a/security/selinux/hooks.c > +++ b/security/selinux/hooks.c > @@ -3849,6 +3849,16 @@ static int selinux_task_movememory(struct task_struct *p) > return current_has_perm(p, PROCESS__SETSCHED); > } > > +static int selinux_task_settimerslack(struct task_struct *p, u64 slack) > +{ > + return current_has_perm(p, PROCESS__SETSCHED); > +} > + > +static int selinux_task_gettimerslack(struct task_struct *p) > +{ > + return current_has_perm(p, PROCESS__GETSCHED); > +} > + > static int selinux_task_kill(struct task_struct *p, struct siginfo *info, > int sig, u32 secid) > { > @@ -6092,6 +6102,8 @@ static struct security_hook_list selinux_hooks[] = { > LSM_HOOK_INIT(task_setscheduler, selinux_task_setscheduler), > LSM_HOOK_INIT(task_getscheduler, selinux_task_getscheduler), > LSM_HOOK_INIT(task_movememory, selinux_task_movememory), > + LSM_HOOK_INIT(task_settimerslack, selinux_task_settimerslack), > + LSM_HOOK_INIT(task_gettimerslack, selinux_task_gettimerslack), > LSM_HOOK_INIT(task_kill, selinux_task_kill), > LSM_HOOK_INIT(task_wait, selinux_task_wait), > LSM_HOOK_INIT(task_to_inode, selinux_task_to_inode), > -- > 1.9.1