X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=kernel%2Fkprobes.c;h=5240d75f4c60e95f95eb55e0cc46b448e2d6eb7c;hb=887965e6576a78f71b9b98dec43fd1c73becd2e8;hp=f9798ff7899f4a610823fd641fe5e2dde0e746f7;hpb=74a0b5762713a26496db72eac34fbbed46f20fce;p=safe%2Fjmp%2Flinux-2.6 diff --git a/kernel/kprobes.c b/kernel/kprobes.c index f9798ff..5240d75 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -43,6 +43,7 @@ #include #include #include +#include #include #include @@ -62,15 +63,35 @@ addr = ((kprobe_opcode_t *)(kallsyms_lookup_name(name))) #endif +static int kprobes_initialized; static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE]; static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE]; /* NOTE: change this value only with kprobe_mutex held */ -static bool kprobe_enabled; +static bool kprobes_all_disarmed; -DEFINE_MUTEX(kprobe_mutex); /* Protects kprobe_table */ -DEFINE_SPINLOCK(kretprobe_lock); /* Protects kretprobe_inst_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; +} kretprobe_table_locks[KPROBE_TABLE_SIZE]; + +static spinlock_t *kretprobe_table_lock_ptr(unsigned long hash) +{ + return &(kretprobe_table_locks[hash].lock); +} + +/* + * Normally, functions that we'd want to prohibit kprobes in, are marked + * __kprobes. But, there are cases where such functions already belong to + * a different section (__sched for preempt_schedule) + * + * For such cases, we now have a blacklist + */ +static struct kprobe_blackpoint kprobe_blacklist[] = { + {"preempt_schedule",}, + {NULL} /* Terminator */ +}; #ifdef __ARCH_WANT_KPROBES_INSN_SLOT /* @@ -82,7 +103,7 @@ static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL; #define INSNS_PER_PAGE (PAGE_SIZE/(MAX_INSN_SIZE * sizeof(kprobe_opcode_t))) struct kprobe_insn_page { - struct hlist_node hlist; + struct list_head list; kprobe_opcode_t *insns; /* Page of instruction slots */ char slot_used[INSNS_PER_PAGE]; int nused; @@ -95,14 +116,15 @@ enum kprobe_slot_state { SLOT_USED = 2, }; -static struct hlist_head kprobe_insn_pages; +static DEFINE_MUTEX(kprobe_insn_mutex); /* Protects kprobe_insn_pages */ +static LIST_HEAD(kprobe_insn_pages); static int kprobe_garbage_slots; static int collect_garbage_slots(void); static int __kprobes check_safety(void) { int ret = 0; -#if defined(CONFIG_PREEMPT) && defined(CONFIG_PM) +#if defined(CONFIG_PREEMPT) && defined(CONFIG_FREEZER) ret = freeze_processes(); if (ret == 0) { struct task_struct *p, *q; @@ -124,16 +146,15 @@ 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; retry: - hlist_for_each_entry(kip, pos, &kprobe_insn_pages, hlist) { + list_for_each_entry(kip, &kprobe_insn_pages, list) { if (kip->nused < INSNS_PER_PAGE) { int i; for (i = 0; i < INSNS_PER_PAGE; i++) { @@ -167,8 +188,8 @@ kprobe_opcode_t __kprobes *get_insn_slot(void) kfree(kip); return NULL; } - INIT_HLIST_NODE(&kip->hlist); - hlist_add_head(&kip->hlist, &kprobe_insn_pages); + INIT_LIST_HEAD(&kip->list); + list_add(&kip->list, &kprobe_insn_pages); memset(kip->slot_used, SLOT_CLEAN, INSNS_PER_PAGE); kip->slot_used[0] = SLOT_USED; kip->nused = 1; @@ -176,6 +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) { @@ -188,12 +218,8 @@ static int __kprobes collect_one_slot(struct kprobe_insn_page *kip, int idx) * so as not to have to set it up again the * next time somebody inserts a probe. */ - hlist_del(&kip->hlist); - if (hlist_empty(&kprobe_insn_pages)) { - INIT_HLIST_NODE(&kip->hlist); - hlist_add_head(&kip->hlist, - &kprobe_insn_pages); - } else { + if (!list_is_singular(&kprobe_insn_pages)) { + list_del(&kip->list); module_free(NULL, kip->insns); kfree(kip); } @@ -204,14 +230,13 @@ static int __kprobes collect_one_slot(struct kprobe_insn_page *kip, int idx) static int __kprobes collect_garbage_slots(void) { - struct kprobe_insn_page *kip; - struct hlist_node *pos, *next; + struct kprobe_insn_page *kip, *next; /* Ensure no-one is preepmted on the garbages */ - if (check_safety() != 0) + if (check_safety()) return -EAGAIN; - hlist_for_each_entry_safe(kip, pos, next, &kprobe_insn_pages, hlist) { + list_for_each_entry_safe(kip, next, &kprobe_insn_pages, list) { int i; if (kip->ngarbage == 0) continue; @@ -229,24 +254,25 @@ static int __kprobes collect_garbage_slots(void) void __kprobes free_insn_slot(kprobe_opcode_t * slot, int dirty) { struct kprobe_insn_page *kip; - struct hlist_node *pos; - hlist_for_each_entry(kip, pos, &kprobe_insn_pages, hlist) { + mutex_lock(&kprobe_insn_mutex); + list_for_each_entry(kip, &kprobe_insn_pages, list) { if (kip->insns <= slot && slot < kip->insns + (INSNS_PER_PAGE * MAX_INSN_SIZE)) { int i = (slot - kip->insns) / MAX_INSN_SIZE; if (dirty) { kip->slot_used[i] = SLOT_DIRTY; kip->ngarbage++; - } else { + } else collect_one_slot(kip, i); - } break; } } if (dirty && ++kprobe_garbage_slots > INSNS_PER_PAGE) collect_garbage_slots(); + + mutex_unlock(&kprobe_insn_mutex); } #endif @@ -281,6 +307,22 @@ struct kprobe __kprobes *get_kprobe(void *addr) return NULL; } +/* Arm a kprobe with text_mutex */ +static void __kprobes arm_kprobe(struct kprobe *kp) +{ + mutex_lock(&text_mutex); + arch_arm_kprobe(kp); + mutex_unlock(&text_mutex); +} + +/* Disarm a kprobe with text_mutex */ +static void __kprobes disarm_kprobe(struct kprobe *kp) +{ + mutex_lock(&text_mutex); + arch_disarm_kprobe(kp); + mutex_unlock(&text_mutex); +} + /* * Aggregate handlers for multiple kprobes support - these handlers * take care of invoking the individual kprobe handlers on p->list @@ -290,7 +332,7 @@ 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 && likely(!kprobe_disabled(kp))) { set_kprobe_instance(kp); if (kp->pre_handler(kp, regs)) return 1; @@ -306,7 +348,7 @@ 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 && likely(!kprobe_disabled(kp))) { set_kprobe_instance(kp); kp->post_handler(kp, regs, flags); reset_kprobe_instance(); @@ -356,26 +398,55 @@ void __kprobes kprobes_inc_nmissed_count(struct kprobe *p) return; } -/* Called with kretprobe_lock held */ void __kprobes recycle_rp_inst(struct kretprobe_instance *ri, struct hlist_head *head) { + struct kretprobe *rp = ri->rp; + /* remove rp inst off the rprobe_inst_table */ hlist_del(&ri->hlist); - if (ri->rp) { - /* remove rp inst off the used list */ - hlist_del(&ri->uflist); - /* put rp inst back onto the free list */ - INIT_HLIST_NODE(&ri->uflist); - hlist_add_head(&ri->uflist, &ri->rp->free_instances); + INIT_HLIST_NODE(&ri->hlist); + if (likely(rp)) { + spin_lock(&rp->lock); + hlist_add_head(&ri->hlist, &rp->free_instances); + spin_unlock(&rp->lock); } else /* Unregistering */ hlist_add_head(&ri->hlist, head); } -struct hlist_head __kprobes *kretprobe_inst_table_head(struct task_struct *tsk) +void __kprobes kretprobe_hash_lock(struct task_struct *tsk, + struct hlist_head **head, unsigned long *flags) { - return &kretprobe_inst_table[hash_ptr(tsk, KPROBE_HASH_BITS)]; + unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS); + spinlock_t *hlist_lock; + + *head = &kretprobe_inst_table[hash]; + hlist_lock = kretprobe_table_lock_ptr(hash); + spin_lock_irqsave(hlist_lock, *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 __kprobes kretprobe_hash_unlock(struct task_struct *tsk, + unsigned long *flags) +{ + unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS); + spinlock_t *hlist_lock; + + hlist_lock = kretprobe_table_lock_ptr(hash); + spin_unlock_irqrestore(hlist_lock, *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); } /* @@ -389,17 +460,21 @@ void __kprobes kprobe_flush_task(struct task_struct *tk) struct kretprobe_instance *ri; struct hlist_head *head, empty_rp; struct hlist_node *node, *tmp; - unsigned long flags = 0; + unsigned long hash, flags = 0; - INIT_HLIST_HEAD(&empty_rp); - spin_lock_irqsave(&kretprobe_lock, flags); - head = kretprobe_inst_table_head(tk); + if (unlikely(!kprobes_initialized)) + /* Early boot. kretprobe_table_locks not yet initialized. */ + return; + + hash = hash_ptr(tk, KPROBE_HASH_BITS); + head = &kretprobe_inst_table[hash]; + kretprobe_table_lock(hash, &flags); hlist_for_each_entry_safe(ri, node, tmp, head, hlist) { if (ri->task == tk) recycle_rp_inst(ri, &empty_rp); } - spin_unlock_irqrestore(&kretprobe_lock, flags); - + kretprobe_table_unlock(hash, &flags); + INIT_HLIST_HEAD(&empty_rp); hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) { hlist_del(&ri->hlist); kfree(ri); @@ -411,12 +486,32 @@ static inline void free_rp_inst(struct kretprobe *rp) struct kretprobe_instance *ri; struct hlist_node *pos, *next; - hlist_for_each_entry_safe(ri, pos, next, &rp->free_instances, uflist) { - hlist_del(&ri->uflist); + hlist_for_each_entry_safe(ri, pos, next, &rp->free_instances, hlist) { + hlist_del(&ri->hlist); kfree(ri); } } +static void __kprobes cleanup_rp_inst(struct kretprobe *rp) +{ + unsigned long flags, hash; + struct kretprobe_instance *ri; + struct hlist_node *pos, *next; + struct hlist_head *head; + + /* No race here */ + for (hash = 0; hash < KPROBE_TABLE_SIZE; hash++) { + kretprobe_table_lock(hash, &flags); + head = &kretprobe_inst_table[hash]; + hlist_for_each_entry_safe(ri, pos, next, head, hlist) { + if (ri->rp == rp) + ri->rp = NULL; + } + kretprobe_table_unlock(hash, &flags); + } + free_rp_inst(rp); +} + /* * Keep all fields in the kprobe consistent */ @@ -427,20 +522,28 @@ static inline void copy_kprobe(struct kprobe *old_p, struct kprobe *p) } /* -* Add the new probe to old_p->list. Fail if this is the +* Add the new probe to ap->list. Fail if this is the * second jprobe at the address - two jprobes can't coexist */ -static int __kprobes add_new_kprobe(struct kprobe *old_p, struct kprobe *p) +static int __kprobes add_new_kprobe(struct kprobe *ap, struct kprobe *p) { + BUG_ON(kprobe_gone(ap) || kprobe_gone(p)); if (p->break_handler) { - if (old_p->break_handler) + if (ap->break_handler) return -EEXIST; - list_add_tail_rcu(&p->list, &old_p->list); - old_p->break_handler = aggr_break_handler; + list_add_tail_rcu(&p->list, &ap->list); + ap->break_handler = aggr_break_handler; } else - list_add_rcu(&p->list, &old_p->list); - if (p->post_handler && !old_p->post_handler) - old_p->post_handler = aggr_post_handler; + list_add_rcu(&p->list, &ap->list); + if (p->post_handler && !ap->post_handler) + ap->post_handler = aggr_post_handler; + + if (kprobe_disabled(ap) && !kprobe_disabled(p)) { + ap->flags &= ~KPROBE_FLAG_DISABLED; + if (!kprobes_all_disarmed) + /* Arm the breakpoint again. */ + arm_kprobe(ap); + } return 0; } @@ -453,11 +556,13 @@ static inline void add_aggr_kprobe(struct kprobe *ap, struct kprobe *p) copy_kprobe(p, ap); flush_insn_slot(ap); ap->addr = p->addr; + ap->flags = p->flags; 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); @@ -474,78 +579,150 @@ static int __kprobes register_aggr_kprobe(struct kprobe *old_p, struct kprobe *p) { int ret = 0; - struct kprobe *ap; + struct kprobe *ap = old_p; - if (old_p->pre_handler == aggr_pre_handler) { - copy_kprobe(old_p, p); - ret = add_new_kprobe(old_p, p); - } else { + if (old_p->pre_handler != aggr_pre_handler) { + /* If old_p is not an aggr_probe, create new aggr_kprobe. */ ap = kzalloc(sizeof(struct kprobe), GFP_KERNEL); if (!ap) return -ENOMEM; add_aggr_kprobe(ap, old_p); - copy_kprobe(ap, p); - ret = add_new_kprobe(ap, p); } - return ret; + + if (kprobe_gone(ap)) { + /* + * 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(ap); + if (ret) + /* + * Even if fail to allocate new slot, don't need to + * free aggr_probe. It will be used next time, or + * freed by unregister_kprobe. + */ + return ret; + + /* + * Clear gone flag to prevent allocating new slot again, and + * set disabled flag because it is not armed yet. + */ + ap->flags = (ap->flags & ~KPROBE_FLAG_GONE) + | KPROBE_FLAG_DISABLED; + } + + copy_kprobe(ap, p); + return add_new_kprobe(ap, p); +} + +/* Try to disable aggr_kprobe, and return 1 if succeeded.*/ +static int __kprobes try_to_disable_aggr_kprobe(struct kprobe *p) +{ + struct kprobe *kp; + + list_for_each_entry_rcu(kp, &p->list, list) { + if (!kprobe_disabled(kp)) + /* + * There is an active probe on the list. + * We can't disable aggr_kprobe. + */ + return 0; + } + p->flags |= KPROBE_FLAG_DISABLED; + return 1; } static int __kprobes in_kprobes_functions(unsigned long addr) { + struct kprobe_blackpoint *kb; + if (addr >= (unsigned long)__kprobes_text_start && addr < (unsigned long)__kprobes_text_end) return -EINVAL; + /* + * If there exists a kprobe_blacklist, verify and + * fail any probe registration in the prohibited area + */ + for (kb = kprobe_blacklist; kb->name != NULL; kb++) { + if (kb->start_addr) { + if (addr >= kb->start_addr && + addr < (kb->start_addr + kb->range)) + return -EINVAL; + } + } return 0; } -static int __kprobes __register_kprobe(struct kprobe *p, - unsigned long called_from) +/* + * If we have a symbol_name argument, look it up and add the offset field + * to it. This way, we can specify a relative address to a symbol. + */ +static kprobe_opcode_t __kprobes *kprobe_addr(struct kprobe *p) +{ + kprobe_opcode_t *addr = p->addr; + if (p->symbol_name) { + if (addr) + return NULL; + kprobe_lookup_name(p->symbol_name, addr); + } + + if (!addr) + return NULL; + return (kprobe_opcode_t *)(((char *)addr) + p->offset); +} + +int __kprobes register_kprobe(struct kprobe *p) { int ret = 0; struct kprobe *old_p; struct module *probed_mod; + kprobe_opcode_t *addr; - /* - * If we have a symbol_name argument look it up, - * and add it to the address. That way the addr - * field can either be global or relative to a symbol. - */ - if (p->symbol_name) { - if (p->addr) - return -EINVAL; - kprobe_lookup_name(p->symbol_name, p->addr); - } - - if (!p->addr) + addr = kprobe_addr(p); + if (!addr) return -EINVAL; - p->addr = (kprobe_opcode_t *)(((char *)p->addr)+ p->offset); + p->addr = addr; + preempt_disable(); if (!kernel_text_address((unsigned long) p->addr) || - in_kprobes_functions((unsigned long) p->addr)) + in_kprobes_functions((unsigned long) p->addr)) { + preempt_enable(); return -EINVAL; + } - p->mod_refcounted = 0; + /* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */ + p->flags &= KPROBE_FLAG_DISABLED; /* * Check if are we probing a module. */ - probed_mod = module_text_address((unsigned long) p->addr); + probed_mod = __module_text_address((unsigned long) p->addr); if (probed_mod) { - struct module *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))) - 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(); p->nmissed = 0; + INIT_LIST_HEAD(&p->list); mutex_lock(&kprobe_mutex); old_p = get_kprobe(p->addr); if (old_p) { @@ -553,100 +730,150 @@ static int __kprobes __register_kprobe(struct kprobe *p, goto out; } + mutex_lock(&text_mutex); ret = arch_prepare_kprobe(p); if (ret) - goto out; + goto out_unlock_text; INIT_HLIST_NODE(&p->hlist); hlist_add_head_rcu(&p->hlist, &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]); - if (kprobe_enabled) + if (!kprobes_all_disarmed && !kprobe_disabled(p)) arch_arm_kprobe(p); +out_unlock_text: + mutex_unlock(&text_mutex); out: mutex_unlock(&kprobe_mutex); - if (ret && probed_mod) + if (probed_mod) module_put(probed_mod); - return ret; -} -int __kprobes register_kprobe(struct kprobe *p) -{ - return __register_kprobe(p, (unsigned long)__builtin_return_address(0)); + return ret; } +EXPORT_SYMBOL_GPL(register_kprobe); -void __kprobes unregister_kprobe(struct kprobe *p) +/* Check passed kprobe is valid and return kprobe in kprobe_table. */ +static struct kprobe * __kprobes __get_valid_kprobe(struct kprobe *p) { - struct module *mod; struct kprobe *old_p, *list_p; - int cleanup_p; - mutex_lock(&kprobe_mutex); old_p = get_kprobe(p->addr); - if (unlikely(!old_p)) { - mutex_unlock(&kprobe_mutex); - return; - } + if (unlikely(!old_p)) + return NULL; + if (p != old_p) { list_for_each_entry_rcu(list_p, &old_p->list, list) if (list_p == p) /* kprobe p is a valid probe */ - goto valid_p; - mutex_unlock(&kprobe_mutex); - return; + goto valid; + return NULL; } -valid_p: +valid: + return old_p; +} + +/* + * Unregister a kprobe without a scheduler synchronization. + */ +static int __kprobes __unregister_kprobe_top(struct kprobe *p) +{ + struct kprobe *old_p, *list_p; + + old_p = __get_valid_kprobe(p); + if (old_p == NULL) + return -EINVAL; + if (old_p == p || (old_p->pre_handler == aggr_pre_handler && - p->list.next == &old_p->list && p->list.prev == &old_p->list)) { + 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) - arch_disarm_kprobe(p); + if (!kprobes_all_disarmed && !kprobe_disabled(old_p)) + disarm_kprobe(p); hlist_del_rcu(&old_p->hlist); - cleanup_p = 1; } else { + if (p->break_handler && !kprobe_gone(p)) + old_p->break_handler = NULL; + 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; + } + old_p->post_handler = NULL; + } +noclean: list_del_rcu(&p->list); - cleanup_p = 0; + if (!kprobe_disabled(old_p)) { + try_to_disable_aggr_kprobe(old_p); + if (!kprobes_all_disarmed && kprobe_disabled(old_p)) + disarm_kprobe(old_p); + } } + return 0; +} - mutex_unlock(&kprobe_mutex); +static void __kprobes __unregister_kprobe_bottom(struct kprobe *p) +{ + struct kprobe *old_p; - synchronize_sched(); - if (p->mod_refcounted) { - mod = module_text_address((unsigned long)p->addr); - if (mod) - module_put(mod); + 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); } +} - if (cleanup_p) { - if (p != old_p) { - list_del_rcu(&p->list); - kfree(old_p); - } - arch_remove_kprobe(p); - } else { - mutex_lock(&kprobe_mutex); - if (p->break_handler) - old_p->break_handler = NULL; - if (p->post_handler){ - list_for_each_entry_rcu(list_p, &old_p->list, list){ - if (list_p->post_handler){ - cleanup_p = 2; - break; - } - } - if (cleanup_p == 0) - old_p->post_handler = NULL; +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]); + if (ret < 0) { + if (i > 0) + unregister_kprobes(kps, i); + break; } - mutex_unlock(&kprobe_mutex); } + return ret; +} +EXPORT_SYMBOL_GPL(register_kprobes); + +void __kprobes unregister_kprobe(struct kprobe *p) +{ + unregister_kprobes(&p, 1); +} +EXPORT_SYMBOL_GPL(unregister_kprobe); + +void __kprobes unregister_kprobes(struct kprobe **kps, int num) +{ + int i; + + if (num <= 0) + return; + mutex_lock(&kprobe_mutex); + for (i = 0; i < num; i++) + if (__unregister_kprobe_top(kps[i]) < 0) + kps[i]->addr = NULL; + mutex_unlock(&kprobe_mutex); + + synchronize_sched(); + for (i = 0; i < num; i++) + if (kps[i]->addr) + __unregister_kprobe_bottom(kps[i]); } +EXPORT_SYMBOL_GPL(unregister_kprobes); static struct notifier_block kprobe_exceptions_nb = { .notifier_call = kprobe_exceptions_notify, @@ -658,28 +885,69 @@ unsigned long __weak arch_deref_entry_point(void *entry) return (unsigned long)entry; } -int __kprobes register_jprobe(struct jprobe *jp) +int __kprobes register_jprobes(struct jprobe **jps, int num) { - unsigned long addr = arch_deref_entry_point(jp->entry); + struct jprobe *jp; + int ret = 0, i; - if (!kernel_text_address(addr)) + if (num <= 0) return -EINVAL; + for (i = 0; i < num; i++) { + unsigned long addr; + jp = jps[i]; + addr = arch_deref_entry_point(jp->entry); + + if (!kernel_text_address(addr)) + ret = -EINVAL; + else { + /* 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); + } + if (ret < 0) { + if (i > 0) + unregister_jprobes(jps, i); + break; + } + } + return ret; +} +EXPORT_SYMBOL_GPL(register_jprobes); - /* Todo: Verify probepoint is a function entry point */ - jp->kp.pre_handler = setjmp_pre_handler; - jp->kp.break_handler = longjmp_break_handler; - - return __register_kprobe(&jp->kp, - (unsigned long)__builtin_return_address(0)); +int __kprobes register_jprobe(struct jprobe *jp) +{ + return register_jprobes(&jp, 1); } +EXPORT_SYMBOL_GPL(register_jprobe); void __kprobes unregister_jprobe(struct jprobe *jp) { - unregister_kprobe(&jp->kp); + unregister_jprobes(&jp, 1); } +EXPORT_SYMBOL_GPL(unregister_jprobe); + +void __kprobes unregister_jprobes(struct jprobe **jps, int num) +{ + int i; + + if (num <= 0) + return; + mutex_lock(&kprobe_mutex); + for (i = 0; i < num; i++) + if (__unregister_kprobe_top(&jps[i]->kp) < 0) + jps[i]->kp.addr = NULL; + mutex_unlock(&kprobe_mutex); -#ifdef ARCH_SUPPORTS_KRETPROBES + synchronize_sched(); + for (i = 0; i < num; i++) { + if (jps[i]->kp.addr) + __unregister_kprobe_bottom(&jps[i]->kp); + } +} +EXPORT_SYMBOL_GPL(unregister_jprobes); +#ifdef CONFIG_KRETPROBES /* * This kprobe pre_handler is registered with every kretprobe. When probe * hits it will set up the return probe. @@ -688,26 +956,35 @@ static int __kprobes pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs) { struct kretprobe *rp = container_of(p, struct kretprobe, kp); - unsigned long flags = 0; + unsigned long hash, flags = 0; + struct kretprobe_instance *ri; /*TODO: consider to only swap the RA after the last pre_handler fired */ - spin_lock_irqsave(&kretprobe_lock, flags); + hash = hash_ptr(current, KPROBE_HASH_BITS); + spin_lock_irqsave(&rp->lock, flags); if (!hlist_empty(&rp->free_instances)) { - struct kretprobe_instance *ri; - ri = hlist_entry(rp->free_instances.first, - struct kretprobe_instance, uflist); + struct kretprobe_instance, hlist); + hlist_del(&ri->hlist); + spin_unlock_irqrestore(&rp->lock, flags); + ri->rp = rp; ri->task = current; + + if (rp->entry_handler && rp->entry_handler(ri, regs)) + return 0; + arch_prepare_kretprobe(ri, regs); /* XXX(hch): why is there no hlist_move_head? */ - hlist_del(&ri->uflist); - hlist_add_head(&ri->uflist, &ri->rp->used_instances); - hlist_add_head(&ri->hlist, kretprobe_inst_table_head(ri->task)); - } else + INIT_HLIST_NODE(&ri->hlist); + kretprobe_table_lock(hash, &flags); + hlist_add_head(&ri->hlist, &kretprobe_inst_table[hash]); + kretprobe_table_unlock(hash, &flags); + } else { rp->nmissed++; - spin_unlock_irqrestore(&kretprobe_lock, flags); + spin_unlock_irqrestore(&rp->lock, flags); + } return 0; } @@ -716,6 +993,18 @@ int __kprobes register_kretprobe(struct kretprobe *rp) int ret = 0; struct kretprobe_instance *inst; int i; + void *addr; + + if (kretprobe_blacklist_size) { + addr = kprobe_addr(&rp->kp); + if (!addr) + return -EINVAL; + + for (i = 0; kretprobe_blacklist[i].name != NULL; i++) { + if (kretprobe_blacklist[i].addr == addr) + return -EINVAL; + } + } rp->kp.pre_handler = pre_handler_kretprobe; rp->kp.post_handler = NULL; @@ -730,32 +1019,96 @@ int __kprobes register_kretprobe(struct kretprobe *rp) rp->maxactive = NR_CPUS; #endif } - INIT_HLIST_HEAD(&rp->used_instances); + spin_lock_init(&rp->lock); INIT_HLIST_HEAD(&rp->free_instances); for (i = 0; i < rp->maxactive; i++) { - inst = kmalloc(sizeof(struct kretprobe_instance), GFP_KERNEL); + inst = kmalloc(sizeof(struct kretprobe_instance) + + rp->data_size, GFP_KERNEL); if (inst == NULL) { free_rp_inst(rp); return -ENOMEM; } - INIT_HLIST_NODE(&inst->uflist); - hlist_add_head(&inst->uflist, &rp->free_instances); + INIT_HLIST_NODE(&inst->hlist); + hlist_add_head(&inst->hlist, &rp->free_instances); } rp->nmissed = 0; /* Establish function entry probe point */ - if ((ret = __register_kprobe(&rp->kp, - (unsigned long)__builtin_return_address(0))) != 0) + ret = register_kprobe(&rp->kp); + if (ret != 0) free_rp_inst(rp); return ret; } +EXPORT_SYMBOL_GPL(register_kretprobe); -#else /* ARCH_SUPPORTS_KRETPROBES */ +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]); + if (ret < 0) { + if (i > 0) + unregister_kretprobes(rps, i); + break; + } + } + return ret; +} +EXPORT_SYMBOL_GPL(register_kretprobes); + +void __kprobes unregister_kretprobe(struct kretprobe *rp) +{ + unregister_kretprobes(&rp, 1); +} +EXPORT_SYMBOL_GPL(unregister_kretprobe); + +void __kprobes unregister_kretprobes(struct kretprobe **rps, int num) +{ + int i; + + if (num <= 0) + return; + mutex_lock(&kprobe_mutex); + for (i = 0; i < num; i++) + if (__unregister_kprobe_top(&rps[i]->kp) < 0) + rps[i]->kp.addr = NULL; + mutex_unlock(&kprobe_mutex); + + synchronize_sched(); + for (i = 0; i < num; i++) { + if (rps[i]->kp.addr) { + __unregister_kprobe_bottom(&rps[i]->kp); + cleanup_rp_inst(rps[i]); + } + } +} +EXPORT_SYMBOL_GPL(unregister_kretprobes); + +#else /* CONFIG_KRETPROBES */ int __kprobes register_kretprobe(struct kretprobe *rp) { return -ENOSYS; } +EXPORT_SYMBOL_GPL(register_kretprobe); + +int __kprobes register_kretprobes(struct kretprobe **rps, int num) +{ + return -ENOSYS; +} +EXPORT_SYMBOL_GPL(register_kretprobes); + +void __kprobes unregister_kretprobe(struct kretprobe *rp) +{ +} +EXPORT_SYMBOL_GPL(unregister_kretprobe); + +void __kprobes unregister_kretprobes(struct kretprobe **rps, int num) +{ +} +EXPORT_SYMBOL_GPL(unregister_kretprobes); static int __kprobes pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs) @@ -763,44 +1116,138 @@ static int __kprobes pre_handler_kretprobe(struct kprobe *p, return 0; } -#endif /* ARCH_SUPPORTS_KRETPROBES */ +#endif /* CONFIG_KRETPROBES */ -void __kprobes unregister_kretprobe(struct kretprobe *rp) +/* Set the kprobe gone and remove its instruction buffer. */ +static void __kprobes kill_kprobe(struct kprobe *p) { - unsigned long flags; - struct kretprobe_instance *ri; - struct hlist_node *pos, *next; + struct kprobe *kp; - unregister_kprobe(&rp->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); +} - /* No race here */ - spin_lock_irqsave(&kretprobe_lock, flags); - hlist_for_each_entry_safe(ri, pos, next, &rp->used_instances, uflist) { - ri->rp = NULL; - hlist_del(&ri->uflist); +/* 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); + } } - spin_unlock_irqrestore(&kretprobe_lock, flags); - free_rp_inst(rp); + 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; + unsigned long offset = 0, size = 0; + char *modname, namebuf[128]; + const char *symbol_name; + void *addr; + struct kprobe_blackpoint *kb; /* FIXME allocate the probe table, currently defined statically */ /* initialize all list heads */ for (i = 0; i < KPROBE_TABLE_SIZE; i++) { INIT_HLIST_HEAD(&kprobe_table[i]); INIT_HLIST_HEAD(&kretprobe_inst_table[i]); + spin_lock_init(&(kretprobe_table_locks[i].lock)); } - /* By default, kprobes are enabled */ - kprobe_enabled = true; + /* + * Lookup and populate the kprobe_blacklist. + * + * Unlike the kretprobe blacklist, we'll need to determine + * the range of addresses that belong to the said functions, + * since a kprobe need not necessarily be at the beginning + * of a function. + */ + for (kb = kprobe_blacklist; kb->name != NULL; kb++) { + kprobe_lookup_name(kb->name, addr); + if (!addr) + continue; + + kb->start_addr = (unsigned long)addr; + symbol_name = kallsyms_lookup(kb->start_addr, + &size, &offset, &modname, namebuf); + if (!symbol_name) + kb->range = 0; + else + kb->range = size; + } + + if (kretprobe_blacklist_size) { + /* lookup the function address from its name */ + for (i = 0; kretprobe_blacklist[i].name != NULL; i++) { + kprobe_lookup_name(kretprobe_blacklist[i].name, + kretprobe_blacklist[i].addr); + if (!kretprobe_blacklist[i].addr) + printk("kretprobe: lookup failed: %s\n", + kretprobe_blacklist[i].name); + } + } + + /* By default, kprobes are armed */ + kprobes_all_disarmed = false; 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) + init_test_probes(); return err; } @@ -817,10 +1264,18 @@ 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%s\n", + p->addr, kprobe_type, sym, offset, + (modname ? modname : " "), + (kprobe_gone(p) ? "[GONE]" : ""), + ((kprobe_disabled(p) && !kprobe_gone(p)) ? + "[DISABLED]" : "")); else - seq_printf(pi, "%p %s %p\n", p->addr, kprobe_type, p->addr); + seq_printf(pi, "%p %s %p %s%s\n", + p->addr, kprobe_type, p->addr, + (kprobe_gone(p) ? "[GONE]" : ""), + ((kprobe_disabled(p) && !kprobe_gone(p)) ? + "[DISABLED]" : "")); } static void __kprobes *kprobe_seq_start(struct seq_file *f, loff_t *pos) @@ -866,7 +1321,7 @@ static int __kprobes show_kprobe_addr(struct seq_file *pi, void *v) return 0; } -static struct seq_operations kprobes_seq_ops = { +static const struct seq_operations kprobes_seq_ops = { .start = kprobe_seq_start, .next = kprobe_seq_next, .stop = kprobe_seq_stop, @@ -878,14 +1333,79 @@ static int __kprobes kprobes_open(struct inode *inode, struct file *filp) return seq_open(filp, &kprobes_seq_ops); } -static struct file_operations debugfs_kprobes_operations = { +static const struct file_operations debugfs_kprobes_operations = { .open = kprobes_open, .read = seq_read, .llseek = seq_lseek, .release = seq_release, }; -static void __kprobes enable_all_kprobes(void) +/* Disable one kprobe */ +int __kprobes disable_kprobe(struct kprobe *kp) +{ + int ret = 0; + struct kprobe *p; + + mutex_lock(&kprobe_mutex); + + /* Check whether specified probe is valid. */ + p = __get_valid_kprobe(kp); + if (unlikely(p == NULL)) { + ret = -EINVAL; + goto out; + } + + /* If the probe is already disabled (or gone), just return */ + if (kprobe_disabled(kp)) + goto out; + + kp->flags |= KPROBE_FLAG_DISABLED; + if (p != kp) + /* When kp != p, p is always enabled. */ + try_to_disable_aggr_kprobe(p); + + if (!kprobes_all_disarmed && kprobe_disabled(p)) + disarm_kprobe(p); +out: + mutex_unlock(&kprobe_mutex); + return ret; +} +EXPORT_SYMBOL_GPL(disable_kprobe); + +/* Enable one kprobe */ +int __kprobes enable_kprobe(struct kprobe *kp) +{ + int ret = 0; + struct kprobe *p; + + mutex_lock(&kprobe_mutex); + + /* Check whether specified probe is valid. */ + p = __get_valid_kprobe(kp); + if (unlikely(p == NULL)) { + ret = -EINVAL; + goto out; + } + + if (kprobe_gone(kp)) { + /* This kprobe has gone, we couldn't enable it. */ + ret = -EINVAL; + goto out; + } + + if (!kprobes_all_disarmed && kprobe_disabled(p)) + arm_kprobe(p); + + p->flags &= ~KPROBE_FLAG_DISABLED; + if (p != kp) + kp->flags &= ~KPROBE_FLAG_DISABLED; +out: + mutex_unlock(&kprobe_mutex); + return ret; +} +EXPORT_SYMBOL_GPL(enable_kprobe); + +static void __kprobes arm_all_kprobes(void) { struct hlist_head *head; struct hlist_node *node; @@ -894,17 +1414,20 @@ static void __kprobes enable_all_kprobes(void) mutex_lock(&kprobe_mutex); - /* If kprobes are already enabled, just return */ - if (kprobe_enabled) + /* If kprobes are armed, just return */ + if (!kprobes_all_disarmed) goto already_enabled; + mutex_lock(&text_mutex); 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_disabled(p)) + arch_arm_kprobe(p); } + mutex_unlock(&text_mutex); - kprobe_enabled = true; + kprobes_all_disarmed = false; printk(KERN_INFO "Kprobes globally enabled\n"); already_enabled: @@ -912,7 +1435,7 @@ already_enabled: return; } -static void __kprobes disable_all_kprobes(void) +static void __kprobes disarm_all_kprobes(void) { struct hlist_head *head; struct hlist_node *node; @@ -921,20 +1444,22 @@ static void __kprobes disable_all_kprobes(void) mutex_lock(&kprobe_mutex); - /* If kprobes are already disabled, just return */ - if (!kprobe_enabled) + /* If kprobes are already disarmed, just return */ + if (kprobes_all_disarmed) goto already_disabled; - kprobe_enabled = false; + kprobes_all_disarmed = true; printk(KERN_INFO "Kprobes globally disabled\n"); + mutex_lock(&text_mutex); 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_disabled(p)) arch_disarm_kprobe(p); } } + mutex_unlock(&text_mutex); mutex_unlock(&kprobe_mutex); /* Allow all currently running kprobes to complete */ synchronize_sched(); @@ -955,7 +1480,7 @@ static ssize_t read_enabled_file_bool(struct file *file, { char buf[3]; - if (kprobe_enabled) + if (!kprobes_all_disarmed) buf[0] = '1'; else buf[0] = '0'; @@ -978,19 +1503,19 @@ static ssize_t write_enabled_file_bool(struct file *file, case 'y': case 'Y': case '1': - enable_all_kprobes(); + arm_all_kprobes(); break; case 'n': case 'N': case '0': - disable_all_kprobes(); + disarm_all_kprobes(); break; } return count; } -static struct file_operations fops_kp = { +static const struct file_operations fops_kp = { .read = read_enabled_file_bool, .write = write_enabled_file_bool, }; @@ -1026,15 +1551,5 @@ late_initcall(debugfs_kprobe_init); module_init(init_kprobes); -EXPORT_SYMBOL_GPL(register_kprobe); -EXPORT_SYMBOL_GPL(unregister_kprobe); -EXPORT_SYMBOL_GPL(register_jprobe); -EXPORT_SYMBOL_GPL(unregister_jprobe); -#ifdef CONFIG_KPROBES +/* defined in arch/.../kernel/kprobes.c */ EXPORT_SYMBOL_GPL(jprobe_return); -#endif - -#ifdef CONFIG_KPROBES -EXPORT_SYMBOL_GPL(register_kretprobe); -EXPORT_SYMBOL_GPL(unregister_kretprobe); -#endif