| Message ID | 1468872671-9002-2-git-send-email-john.stultz@linaro.org (mailing list archive) |
|---|---|
| State | RFC |
| Headers | show |
On Mon, Jul 18, 2016 at 1:11 PM, John Stultz <john.stultz@linaro.org> wrote: > As requested, this patch implements a task_settimerslack and > task_gettimerslack LSM hooks so that the /proc/<tid>/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! Looks good. Thanks! Reviewed-by: Nick Kralevich <nnk@google.com> > > Cc: Kees Cook <keescook@chromium.org> > Cc: "Serge E. Hallyn" <serge@hallyn.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Thomas Gleixner <tglx@linutronix.de> > CC: Arjan van de Ven <arjan@linux.intel.com> > Cc: Oren Laadan <orenl@cellrox.com> > Cc: Ruchi Kandoi <kandoiruchi@google.com> > Cc: Rom Lemarchand <romlem@android.com> > Cc: Todd Kjos <tkjos@google.com> > Cc: Colin Cross <ccross@android.com> > Cc: Nick Kralevich <nnk@google.com> > Cc: Dmitry Shmidt <dimitrysh@google.com> > Cc: Elliott Hughes <enh@google.com> > Cc: Android Kernel Team <kernel-team@android.com> > Cc: linux-security-module@vger.kernel.org > Cc: selinux@tycho.nsa.gov > Signed-off-by: John Stultz <john.stultz@linaro.org> > --- > 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 >
Quoting John Stultz (john.stultz@linaro.org): > As requested, this patch implements a task_settimerslack and > task_gettimerslack LSM hooks so that the /proc/<tid>/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 <keescook@chromium.org> > Cc: "Serge E. Hallyn" <serge@hallyn.com> Acked-by: Serge Hallyn <serge@hallyn.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Thomas Gleixner <tglx@linutronix.de> > CC: Arjan van de Ven <arjan@linux.intel.com> > Cc: Oren Laadan <orenl@cellrox.com> > Cc: Ruchi Kandoi <kandoiruchi@google.com> > Cc: Rom Lemarchand <romlem@android.com> > Cc: Todd Kjos <tkjos@google.com> > Cc: Colin Cross <ccross@android.com> > Cc: Nick Kralevich <nnk@google.com> > Cc: Dmitry Shmidt <dimitrysh@google.com> > Cc: Elliott Hughes <enh@google.com> > Cc: Android Kernel Team <kernel-team@android.com> > Cc: linux-security-module@vger.kernel.org > Cc: selinux@tycho.nsa.gov > Signed-off-by: John Stultz <john.stultz@linaro.org> > --- > 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
On Mon, Jul 18, 2016 at 1:11 PM, John Stultz <john.stultz@linaro.org> wrote: > As requested, this patch implements a task_settimerslack and > task_gettimerslack LSM hooks so that the /proc/<tid>/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. Yeah, I think this does make it more readable in the end. > > Don't really know what I'm doing here, so close review would be > appreciated! > > Cc: Kees Cook <keescook@chromium.org> > Cc: "Serge E. Hallyn" <serge@hallyn.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Thomas Gleixner <tglx@linutronix.de> > CC: Arjan van de Ven <arjan@linux.intel.com> > Cc: Oren Laadan <orenl@cellrox.com> > Cc: Ruchi Kandoi <kandoiruchi@google.com> > Cc: Rom Lemarchand <romlem@android.com> > Cc: Todd Kjos <tkjos@google.com> > Cc: Colin Cross <ccross@android.com> > Cc: Nick Kralevich <nnk@google.com> > Cc: Dmitry Shmidt <dimitrysh@google.com> > Cc: Elliott Hughes <enh@google.com> > Cc: Android Kernel Team <kernel-team@android.com> > Cc: linux-security-module@vger.kernel.org > Cc: selinux@tycho.nsa.gov > Signed-off-by: John Stultz <john.stultz@linaro.org> Acked-by: Kees Cook <keescook@chromium.org> -Kees > --- > 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 >
On Tue, Jul 19, 2016 at 11:12 PM, James Morris <jmorris@namei.org> wrote: > On Mon, 18 Jul 2016, John Stultz wrote: > >> As requested, this patch implements a task_settimerslack and >> task_gettimerslack LSM hooks so that the /proc/<tid>/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. >> > > I may have missed something in the earlier discussion, but why do we need > new LSM hooks here vs. calling the existing set/getscheduler hooks? Mostly since adding a new hook was suggested originally. I don't think there's much difference as it stands, but I guess more fine grained checks could be added on the slack amounts, etc. I can rework it, so let me know if using the existing hooks would be preferred, but otherwise I'll be sending out the non-rfc patches tomorrow. thanks -john
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),
As requested, this patch implements a task_settimerslack and task_gettimerslack LSM hooks so that the /proc/<tid>/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 <keescook@chromium.org> Cc: "Serge E. Hallyn" <serge@hallyn.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> CC: Arjan van de Ven <arjan@linux.intel.com> Cc: Oren Laadan <orenl@cellrox.com> Cc: Ruchi Kandoi <kandoiruchi@google.com> Cc: Rom Lemarchand <romlem@android.com> Cc: Todd Kjos <tkjos@google.com> Cc: Colin Cross <ccross@android.com> Cc: Nick Kralevich <nnk@google.com> Cc: Dmitry Shmidt <dimitrysh@google.com> Cc: Elliott Hughes <enh@google.com> Cc: Android Kernel Team <kernel-team@android.com> Cc: linux-security-module@vger.kernel.org Cc: selinux@tycho.nsa.gov Signed-off-by: John Stultz <john.stultz@linaro.org> --- 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(+)