diff options
Diffstat (limited to 'kernel/kprobes.c')
| -rw-r--r-- | kernel/kprobes.c | 281 |
1 files changed, 175 insertions, 106 deletions
diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 9f8a3f2..1b9cbdc 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -69,7 +69,7 @@ static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE]; /* NOTE: change this value only with kprobe_mutex held */ static bool kprobe_enabled; -DEFINE_MUTEX(kprobe_mutex); /* Protects kprobe_table */ +static DEFINE_MUTEX(kprobe_mutex); /* Protects kprobe_table */ static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL; static struct { spinlock_t lock ____cacheline_aligned_in_smp; @@ -115,6 +115,7 @@ enum kprobe_slot_state { SLOT_USED = 2, }; +static DEFINE_MUTEX(kprobe_insn_mutex); /* Protects kprobe_insn_pages */ static struct hlist_head kprobe_insn_pages; static int kprobe_garbage_slots; static int collect_garbage_slots(void); @@ -144,10 +145,10 @@ loop_end: } /** - * get_insn_slot() - Find a slot on an executable page for an instruction. + * __get_insn_slot() - Find a slot on an executable page for an instruction. * We allocate an executable page if there's no room on existing ones. */ -kprobe_opcode_t __kprobes *get_insn_slot(void) +static kprobe_opcode_t __kprobes *__get_insn_slot(void) { struct kprobe_insn_page *kip; struct hlist_node *pos; @@ -196,6 +197,15 @@ kprobe_opcode_t __kprobes *get_insn_slot(void) return kip->insns; } +kprobe_opcode_t __kprobes *get_insn_slot(void) +{ + kprobe_opcode_t *ret; + mutex_lock(&kprobe_insn_mutex); + ret = __get_insn_slot(); + mutex_unlock(&kprobe_insn_mutex); + return ret; +} + /* Return 1 if all garbages are collected, otherwise 0. */ static int __kprobes collect_one_slot(struct kprobe_insn_page *kip, int idx) { @@ -226,9 +236,13 @@ static int __kprobes collect_garbage_slots(void) { struct kprobe_insn_page *kip; struct hlist_node *pos, *next; + int safety; /* Ensure no-one is preepmted on the garbages */ - if (check_safety() != 0) + mutex_unlock(&kprobe_insn_mutex); + safety = check_safety(); + mutex_lock(&kprobe_insn_mutex); + if (safety != 0) return -EAGAIN; hlist_for_each_entry_safe(kip, pos, next, &kprobe_insn_pages, hlist) { @@ -251,6 +265,7 @@ void __kprobes free_insn_slot(kprobe_opcode_t * slot, int dirty) struct kprobe_insn_page *kip; struct hlist_node *pos; + mutex_lock(&kprobe_insn_mutex); hlist_for_each_entry(kip, pos, &kprobe_insn_pages, hlist) { if (kip->insns <= slot && slot < kip->insns + (INSNS_PER_PAGE * MAX_INSN_SIZE)) { @@ -267,6 +282,8 @@ void __kprobes free_insn_slot(kprobe_opcode_t * slot, int dirty) if (dirty && ++kprobe_garbage_slots > INSNS_PER_PAGE) collect_garbage_slots(); + + mutex_unlock(&kprobe_insn_mutex); } #endif @@ -310,7 +327,7 @@ static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs) struct kprobe *kp; list_for_each_entry_rcu(kp, &p->list, list) { - if (kp->pre_handler) { + if (kp->pre_handler && !kprobe_gone(kp)) { set_kprobe_instance(kp); if (kp->pre_handler(kp, regs)) return 1; @@ -326,7 +343,7 @@ static void __kprobes aggr_post_handler(struct kprobe *p, struct pt_regs *regs, struct kprobe *kp; list_for_each_entry_rcu(kp, &p->list, list) { - if (kp->post_handler) { + if (kp->post_handler && !kprobe_gone(kp)) { set_kprobe_instance(kp); kp->post_handler(kp, regs, flags); reset_kprobe_instance(); @@ -393,7 +410,7 @@ void __kprobes recycle_rp_inst(struct kretprobe_instance *ri, hlist_add_head(&ri->hlist, head); } -void kretprobe_hash_lock(struct task_struct *tsk, +void __kprobes kretprobe_hash_lock(struct task_struct *tsk, struct hlist_head **head, unsigned long *flags) { unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS); @@ -404,13 +421,15 @@ void kretprobe_hash_lock(struct task_struct *tsk, spin_lock_irqsave(hlist_lock, *flags); } -static void kretprobe_table_lock(unsigned long hash, unsigned long *flags) +static void __kprobes kretprobe_table_lock(unsigned long hash, + unsigned long *flags) { spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash); spin_lock_irqsave(hlist_lock, *flags); } -void kretprobe_hash_unlock(struct task_struct *tsk, unsigned long *flags) +void __kprobes kretprobe_hash_unlock(struct task_struct *tsk, + unsigned long *flags) { unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS); spinlock_t *hlist_lock; @@ -419,7 +438,7 @@ void kretprobe_hash_unlock(struct task_struct *tsk, unsigned long *flags) spin_unlock_irqrestore(hlist_lock, *flags); } -void kretprobe_table_unlock(unsigned long hash, unsigned long *flags) +void __kprobes kretprobe_table_unlock(unsigned long hash, unsigned long *flags) { spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash); spin_unlock_irqrestore(hlist_lock, *flags); @@ -526,9 +545,10 @@ static inline void add_aggr_kprobe(struct kprobe *ap, struct kprobe *p) ap->addr = p->addr; ap->pre_handler = aggr_pre_handler; ap->fault_handler = aggr_fault_handler; - if (p->post_handler) + /* We don't care the kprobe which has gone. */ + if (p->post_handler && !kprobe_gone(p)) ap->post_handler = aggr_post_handler; - if (p->break_handler) + if (p->break_handler && !kprobe_gone(p)) ap->break_handler = aggr_break_handler; INIT_LIST_HEAD(&ap->list); @@ -547,17 +567,41 @@ static int __kprobes register_aggr_kprobe(struct kprobe *old_p, int ret = 0; struct kprobe *ap; + if (kprobe_gone(old_p)) { + /* + * Attempting to insert new probe at the same location that + * had a probe in the module vaddr area which already + * freed. So, the instruction slot has already been + * released. We need a new slot for the new probe. + */ + ret = arch_prepare_kprobe(old_p); + if (ret) + return ret; + } if (old_p->pre_handler == aggr_pre_handler) { copy_kprobe(old_p, p); ret = add_new_kprobe(old_p, p); + ap = old_p; } else { ap = kzalloc(sizeof(struct kprobe), GFP_KERNEL); - if (!ap) + if (!ap) { + if (kprobe_gone(old_p)) + arch_remove_kprobe(old_p); return -ENOMEM; + } add_aggr_kprobe(ap, old_p); copy_kprobe(ap, p); ret = add_new_kprobe(ap, p); } + if (kprobe_gone(old_p)) { + /* + * If the old_p has gone, its breakpoint has been disarmed. + * We have to arm it again after preparing real kprobes. + */ + ap->flags &= ~KPROBE_FLAG_GONE; + if (kprobe_enabled) + arch_arm_kprobe(ap); + } return ret; } @@ -600,8 +644,7 @@ static kprobe_opcode_t __kprobes *kprobe_addr(struct kprobe *p) return (kprobe_opcode_t *)(((char *)addr) + p->offset); } -static int __kprobes __register_kprobe(struct kprobe *p, - unsigned long called_from) +int __kprobes register_kprobe(struct kprobe *p) { int ret = 0; struct kprobe *old_p; @@ -620,28 +663,30 @@ static int __kprobes __register_kprobe(struct kprobe *p, return -EINVAL; } - p->mod_refcounted = 0; - + p->flags = 0; /* * Check if are we probing a module. */ probed_mod = __module_text_address((unsigned long) p->addr); if (probed_mod) { - struct module *calling_mod; - calling_mod = __module_text_address(called_from); /* - * We must allow modules to probe themself and in this case - * avoid incrementing the module refcount, so as to allow - * unloading of self probing modules. + * We must hold a refcount of the probed module while updating + * its code to prohibit unexpected unloading. */ - if (calling_mod && calling_mod != probed_mod) { - if (unlikely(!try_module_get(probed_mod))) { - preempt_enable(); - return -EINVAL; - } - p->mod_refcounted = 1; - } else - probed_mod = NULL; + if (unlikely(!try_module_get(probed_mod))) { + preempt_enable(); + return -EINVAL; + } + /* + * If the module freed .init.text, we couldn't insert + * kprobes in there. + */ + if (within_module_init((unsigned long)p->addr, probed_mod) && + probed_mod->state != MODULE_STATE_COMING) { + module_put(probed_mod); + preempt_enable(); + return -EINVAL; + } } preempt_enable(); @@ -668,8 +713,9 @@ static int __kprobes __register_kprobe(struct kprobe *p, out: mutex_unlock(&kprobe_mutex); - if (ret && probed_mod) + if (probed_mod) module_put(probed_mod); + return ret; } @@ -697,16 +743,16 @@ valid_p: list_is_singular(&old_p->list))) { /* * Only probe on the hash list. Disarm only if kprobes are - * enabled - otherwise, the breakpoint would already have - * been removed. We save on flushing icache. + * enabled and not gone - otherwise, the breakpoint would + * already have been removed. We save on flushing icache. */ - if (kprobe_enabled) + if (kprobe_enabled && !kprobe_gone(old_p)) arch_disarm_kprobe(p); hlist_del_rcu(&old_p->hlist); } else { - if (p->break_handler) + if (p->break_handler && !kprobe_gone(p)) old_p->break_handler = NULL; - if (p->post_handler) { + if (p->post_handler && !kprobe_gone(p)) { list_for_each_entry_rcu(list_p, &old_p->list, list) { if ((list_p != p) && (list_p->post_handler)) goto noclean; @@ -721,39 +767,27 @@ noclean: static void __kprobes __unregister_kprobe_bottom(struct kprobe *p) { - struct module *mod; struct kprobe *old_p; - if (p->mod_refcounted) { - /* - * Since we've already incremented refcount, - * we don't need to disable preemption. - */ - mod = module_text_address((unsigned long)p->addr); - if (mod) - module_put(mod); - } - - if (list_empty(&p->list) || list_is_singular(&p->list)) { - if (!list_empty(&p->list)) { - /* "p" is the last child of an aggr_kprobe */ - old_p = list_entry(p->list.next, struct kprobe, list); - list_del(&p->list); - kfree(old_p); - } + if (list_empty(&p->list)) arch_remove_kprobe(p); + else if (list_is_singular(&p->list)) { + /* "p" is the last child of an aggr_kprobe */ + old_p = list_entry(p->list.next, struct kprobe, list); + list_del(&p->list); + arch_remove_kprobe(old_p); + kfree(old_p); } } -static int __register_kprobes(struct kprobe **kps, int num, - unsigned long called_from) +int __kprobes register_kprobes(struct kprobe **kps, int num) { int i, ret = 0; if (num <= 0) return -EINVAL; for (i = 0; i < num; i++) { - ret = __register_kprobe(kps[i], called_from); + ret = register_kprobe(kps[i]); if (ret < 0) { if (i > 0) unregister_kprobes(kps, i); @@ -763,26 +797,11 @@ static int __register_kprobes(struct kprobe **kps, int num, return ret; } -/* - * Registration and unregistration functions for kprobe. - */ -int __kprobes register_kprobe(struct kprobe *p) -{ - return __register_kprobes(&p, 1, - (unsigned long)__builtin_return_address(0)); -} - void __kprobes unregister_kprobe(struct kprobe *p) { unregister_kprobes(&p, 1); } -int __kprobes register_kprobes(struct kprobe **kps, int num) -{ - return __register_kprobes(kps, num, - (unsigned long)__builtin_return_address(0)); -} - void __kprobes unregister_kprobes(struct kprobe **kps, int num) { int i; @@ -811,8 +830,7 @@ unsigned long __weak arch_deref_entry_point(void *entry) return (unsigned long)entry; } -static int __register_jprobes(struct jprobe **jps, int num, - unsigned long called_from) +int __kprobes register_jprobes(struct jprobe **jps, int num) { struct jprobe *jp; int ret = 0, i; @@ -830,7 +848,7 @@ static int __register_jprobes(struct jprobe **jps, int num, /* Todo: Verify probepoint is a function entry point */ jp->kp.pre_handler = setjmp_pre_handler; jp->kp.break_handler = longjmp_break_handler; - ret = __register_kprobe(&jp->kp, called_from); + ret = register_kprobe(&jp->kp); } if (ret < 0) { if (i > 0) @@ -843,8 +861,7 @@ static int __register_jprobes(struct jprobe **jps, int num, int __kprobes register_jprobe(struct jprobe *jp) { - return __register_jprobes(&jp, 1, - (unsigned long)__builtin_return_address(0)); + return register_jprobes(&jp, 1); } void __kprobes unregister_jprobe(struct jprobe *jp) @@ -852,12 +869,6 @@ void __kprobes unregister_jprobe(struct jprobe *jp) unregister_jprobes(&jp, 1); } -int __kprobes register_jprobes(struct jprobe **jps, int num) -{ - return __register_jprobes(jps, num, - (unsigned long)__builtin_return_address(0)); -} - void __kprobes unregister_jprobes(struct jprobe **jps, int num) { int i; @@ -920,8 +931,7 @@ static int __kprobes pre_handler_kretprobe(struct kprobe *p, return 0; } -static int __kprobes __register_kretprobe(struct kretprobe *rp, - unsigned long called_from) +int __kprobes register_kretprobe(struct kretprobe *rp) { int ret = 0; struct kretprobe_instance *inst; @@ -967,21 +977,20 @@ static int __kprobes __register_kretprobe(struct kretprobe *rp, rp->nmissed = 0; /* Establish function entry probe point */ - ret = __register_kprobe(&rp->kp, called_from); + ret = register_kprobe(&rp->kp); if (ret != 0) free_rp_inst(rp); return ret; } -static int __register_kretprobes(struct kretprobe **rps, int num, - unsigned long called_from) +int __kprobes register_kretprobes(struct kretprobe **rps, int num) { int ret = 0, i; if (num <= 0) return -EINVAL; for (i = 0; i < num; i++) { - ret = __register_kretprobe(rps[i], called_from); + ret = register_kretprobe(rps[i]); if (ret < 0) { if (i > 0) unregister_kretprobes(rps, i); @@ -991,23 +1000,11 @@ static int __register_kretprobes(struct kretprobe **rps, int num, return ret; } -int __kprobes register_kretprobe(struct kretprobe *rp) -{ - return __register_kretprobes(&rp, 1, - (unsigned long)__builtin_return_address(0)); -} - void __kprobes unregister_kretprobe(struct kretprobe *rp) { unregister_kretprobes(&rp, 1); } -int __kprobes register_kretprobes(struct kretprobe **rps, int num) -{ - return __register_kretprobes(rps, num, - (unsigned long)__builtin_return_address(0)); -} - void __kprobes unregister_kretprobes(struct kretprobe **rps, int num) { int i; @@ -1055,6 +1052,72 @@ static int __kprobes pre_handler_kretprobe(struct kprobe *p, #endif /* CONFIG_KRETPROBES */ +/* Set the kprobe gone and remove its instruction buffer. */ +static void __kprobes kill_kprobe(struct kprobe *p) +{ + struct kprobe *kp; + p->flags |= KPROBE_FLAG_GONE; + if (p->pre_handler == aggr_pre_handler) { + /* + * If this is an aggr_kprobe, we have to list all the + * chained probes and mark them GONE. + */ + list_for_each_entry_rcu(kp, &p->list, list) + kp->flags |= KPROBE_FLAG_GONE; + p->post_handler = NULL; + p->break_handler = NULL; + } + /* + * Here, we can remove insn_slot safely, because no thread calls + * the original probed function (which will be freed soon) any more. + */ + arch_remove_kprobe(p); +} + +/* Module notifier call back, checking kprobes on the module */ +static int __kprobes kprobes_module_callback(struct notifier_block *nb, + unsigned long val, void *data) +{ + struct module *mod = data; + struct hlist_head *head; + struct hlist_node *node; + struct kprobe *p; + unsigned int i; + int checkcore = (val == MODULE_STATE_GOING); + + if (val != MODULE_STATE_GOING && val != MODULE_STATE_LIVE) + return NOTIFY_DONE; + + /* + * When MODULE_STATE_GOING was notified, both of module .text and + * .init.text sections would be freed. When MODULE_STATE_LIVE was + * notified, only .init.text section would be freed. We need to + * disable kprobes which have been inserted in the sections. + */ + mutex_lock(&kprobe_mutex); + for (i = 0; i < KPROBE_TABLE_SIZE; i++) { + head = &kprobe_table[i]; + hlist_for_each_entry_rcu(p, node, head, hlist) + if (within_module_init((unsigned long)p->addr, mod) || + (checkcore && + within_module_core((unsigned long)p->addr, mod))) { + /* + * The vaddr this probe is installed will soon + * be vfreed buy not synced to disk. Hence, + * disarming the breakpoint isn't needed. + */ + kill_kprobe(p); + } + } + mutex_unlock(&kprobe_mutex); + return NOTIFY_DONE; +} + +static struct notifier_block kprobe_module_nb = { + .notifier_call = kprobes_module_callback, + .priority = 0 +}; + static int __init init_kprobes(void) { int i, err = 0; @@ -1111,6 +1174,9 @@ static int __init init_kprobes(void) err = arch_init_kprobes(); if (!err) err = register_die_notifier(&kprobe_exceptions_nb); + if (!err) + err = register_module_notifier(&kprobe_module_nb); + kprobes_initialized = (err == 0); if (!err) @@ -1131,10 +1197,12 @@ static void __kprobes report_probe(struct seq_file *pi, struct kprobe *p, else kprobe_type = "k"; if (sym) - seq_printf(pi, "%p %s %s+0x%x %s\n", p->addr, kprobe_type, - sym, offset, (modname ? modname : " ")); + seq_printf(pi, "%p %s %s+0x%x %s %s\n", p->addr, kprobe_type, + sym, offset, (modname ? modname : " "), + (kprobe_gone(p) ? "[GONE]" : "")); else - seq_printf(pi, "%p %s %p\n", p->addr, kprobe_type, p->addr); + seq_printf(pi, "%p %s %p %s\n", p->addr, kprobe_type, p->addr, + (kprobe_gone(p) ? "[GONE]" : "")); } static void __kprobes *kprobe_seq_start(struct seq_file *f, loff_t *pos) @@ -1215,7 +1283,8 @@ static void __kprobes enable_all_kprobes(void) for (i = 0; i < KPROBE_TABLE_SIZE; i++) { head = &kprobe_table[i]; hlist_for_each_entry_rcu(p, node, head, hlist) - arch_arm_kprobe(p); + if (!kprobe_gone(p)) + arch_arm_kprobe(p); } kprobe_enabled = true; @@ -1244,7 +1313,7 @@ static void __kprobes disable_all_kprobes(void) for (i = 0; i < KPROBE_TABLE_SIZE; i++) { head = &kprobe_table[i]; hlist_for_each_entry_rcu(p, node, head, hlist) { - if (!arch_trampoline_kprobe(p)) + if (!arch_trampoline_kprobe(p) && !kprobe_gone(p)) arch_disarm_kprobe(p); } } |
