diff options
Diffstat (limited to 'kernel/livepatch')
-rw-r--r-- | kernel/livepatch/core.c | 30 | ||||
-rw-r--r-- | kernel/livepatch/transition.c | 36 | ||||
-rw-r--r-- | kernel/livepatch/transition.h | 1 |
3 files changed, 65 insertions, 2 deletions
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c index 88766bd..1c3c9b2 100644 --- a/kernel/livepatch/core.c +++ b/kernel/livepatch/core.c @@ -455,6 +455,7 @@ EXPORT_SYMBOL_GPL(klp_enable_patch); * /sys/kernel/livepatch/<patch>/enabled * /sys/kernel/livepatch/<patch>/transition * /sys/kernel/livepatch/<patch>/signal + * /sys/kernel/livepatch/<patch>/force * /sys/kernel/livepatch/<patch>/<object> * /sys/kernel/livepatch/<patch>/<object>/<function,sympos> */ @@ -556,13 +557,42 @@ static ssize_t signal_store(struct kobject *kobj, struct kobj_attribute *attr, return count; } +static ssize_t force_store(struct kobject *kobj, struct kobj_attribute *attr, + const char *buf, size_t count) +{ + struct klp_patch *patch; + int ret; + bool val; + + patch = container_of(kobj, struct klp_patch, kobj); + + /* + * klp_mutex lock is not grabbed here intentionally. It is not really + * needed. The race window is harmless and grabbing the lock would only + * hold the action back. + */ + if (patch != klp_transition_patch) + return -EINVAL; + + ret = kstrtobool(buf, &val); + if (ret) + return ret; + + if (val) + klp_force_transition(); + + return count; +} + static struct kobj_attribute enabled_kobj_attr = __ATTR_RW(enabled); static struct kobj_attribute transition_kobj_attr = __ATTR_RO(transition); static struct kobj_attribute signal_kobj_attr = __ATTR_WO(signal); +static struct kobj_attribute force_kobj_attr = __ATTR_WO(force); static struct attribute *klp_patch_attrs[] = { &enabled_kobj_attr.attr, &transition_kobj_attr.attr, &signal_kobj_attr.attr, + &force_kobj_attr.attr, NULL }; diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c index edcfcb8..be5bfa5 100644 --- a/kernel/livepatch/transition.c +++ b/kernel/livepatch/transition.c @@ -33,6 +33,8 @@ struct klp_patch *klp_transition_patch; static int klp_target_state = KLP_UNDEFINED; +static bool klp_forced = false; + /* * This work can be performed periodically to finish patching or unpatching any * "straggler" tasks which failed to transition in the first attempt. @@ -146,9 +148,12 @@ done: /* * See complementary comment in __klp_enable_patch() for why we * keep the module reference for immediate patches. + * + * klp_forced or immediate_func set implies unbounded increase of + * module's ref count if the module is disabled/enabled in a loop. */ - if (!klp_transition_patch->immediate && !immediate_func && - klp_target_state == KLP_UNPATCHED) { + if (!klp_forced && !klp_transition_patch->immediate && + !immediate_func && klp_target_state == KLP_UNPATCHED) { module_put(klp_transition_patch->mod); } @@ -649,3 +654,30 @@ void klp_send_signals(void) } read_unlock(&tasklist_lock); } + +/* + * Drop TIF_PATCH_PENDING of all tasks on admin's request. This forces an + * existing transition to finish. + * + * NOTE: klp_update_patch_state(task) requires the task to be inactive or + * 'current'. This is not the case here and the consistency model could be + * broken. Administrator, who is the only one to execute the + * klp_force_transitions(), has to be aware of this. + */ +void klp_force_transition(void) +{ + struct task_struct *g, *task; + unsigned int cpu; + + pr_warn("forcing remaining tasks to the patched state\n"); + + read_lock(&tasklist_lock); + for_each_process_thread(g, task) + klp_update_patch_state(task); + read_unlock(&tasklist_lock); + + for_each_possible_cpu(cpu) + klp_update_patch_state(idle_task(cpu)); + + klp_forced = true; +} diff --git a/kernel/livepatch/transition.h b/kernel/livepatch/transition.h index 4052279..f9d0bc0 100644 --- a/kernel/livepatch/transition.h +++ b/kernel/livepatch/transition.h @@ -12,5 +12,6 @@ void klp_start_transition(void); void klp_try_complete_transition(void); void klp_reverse_transition(void); void klp_send_signals(void); +void klp_force_transition(void); #endif /* _LIVEPATCH_TRANSITION_H */ |