diff options
Diffstat (limited to 'kernel/kprobes.c')
| -rw-r--r-- | kernel/kprobes.c | 1355 |
1 files changed, 1355 insertions, 0 deletions
diff --git a/kernel/kprobes.c b/kernel/kprobes.c new file mode 100644 index 0000000..9f8a3f2 --- /dev/null +++ b/kernel/kprobes.c @@ -0,0 +1,1355 @@ +/* + * Kernel Probes (KProbes) + * kernel/kprobes.c + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * + * Copyright (C) IBM Corporation, 2002, 2004 + * + * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel + * Probes initial implementation (includes suggestions from + * Rusty Russell). + * 2004-Aug Updated by Prasanna S Panchamukhi <prasanna@in.ibm.com> with + * hlists and exceptions notifier as suggested by Andi Kleen. + * 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes + * interface to access function arguments. + * 2004-Sep Prasanna S Panchamukhi <prasanna@in.ibm.com> Changed Kprobes + * exceptions notifier to be first on the priority list. + * 2005-May Hien Nguyen <hien@us.ibm.com>, Jim Keniston + * <jkenisto@us.ibm.com> and Prasanna S Panchamukhi + * <prasanna@in.ibm.com> added function-return probes. + */ +#include <linux/kprobes.h> +#include <linux/hash.h> +#include <linux/init.h> +#include <linux/slab.h> +#include <linux/stddef.h> +#include <linux/module.h> +#include <linux/moduleloader.h> +#include <linux/kallsyms.h> +#include <linux/freezer.h> +#include <linux/seq_file.h> +#include <linux/debugfs.h> +#include <linux/kdebug.h> + +#include <asm-generic/sections.h> +#include <asm/cacheflush.h> +#include <asm/errno.h> +#include <asm/uaccess.h> + +#define KPROBE_HASH_BITS 6 +#define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS) + + +/* + * Some oddball architectures like 64bit powerpc have function descriptors + * so this must be overridable. + */ +#ifndef kprobe_lookup_name +#define kprobe_lookup_name(name, addr) \ + 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; + +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 +/* + * kprobe->ainsn.insn points to the copy of the instruction to be + * single-stepped. x86_64, POWER4 and above have no-exec support and + * stepping on the instruction on a vmalloced/kmalloced/data page + * is a recipe for disaster + */ +#define INSNS_PER_PAGE (PAGE_SIZE/(MAX_INSN_SIZE * sizeof(kprobe_opcode_t))) + +struct kprobe_insn_page { + struct hlist_node hlist; + kprobe_opcode_t *insns; /* Page of instruction slots */ + char slot_used[INSNS_PER_PAGE]; + int nused; + int ngarbage; +}; + +enum kprobe_slot_state { + SLOT_CLEAN = 0, + SLOT_DIRTY = 1, + SLOT_USED = 2, +}; + +static struct hlist_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) + ret = freeze_processes(); + if (ret == 0) { + struct task_struct *p, *q; + do_each_thread(p, q) { + if (p != current && p->state == TASK_RUNNING && + p->pid != 0) { + printk("Check failed: %s is running\n",p->comm); + ret = -1; + goto loop_end; + } + } while_each_thread(p, q); + } +loop_end: + thaw_processes(); +#else + synchronize_sched(); +#endif + return ret; +} + +/** + * 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) +{ + struct kprobe_insn_page *kip; + struct hlist_node *pos; + + retry: + hlist_for_each_entry(kip, pos, &kprobe_insn_pages, hlist) { + if (kip->nused < INSNS_PER_PAGE) { + int i; + for (i = 0; i < INSNS_PER_PAGE; i++) { + if (kip->slot_used[i] == SLOT_CLEAN) { + kip->slot_used[i] = SLOT_USED; + kip->nused++; + return kip->insns + (i * MAX_INSN_SIZE); + } + } + /* Surprise! No unused slots. Fix kip->nused. */ + kip->nused = INSNS_PER_PAGE; + } + } + + /* If there are any garbage slots, collect it and try again. */ + if (kprobe_garbage_slots && collect_garbage_slots() == 0) { + goto retry; + } + /* All out of space. Need to allocate a new page. Use slot 0. */ + kip = kmalloc(sizeof(struct kprobe_insn_page), GFP_KERNEL); + if (!kip) + return NULL; + + /* + * Use module_alloc so this page is within +/- 2GB of where the + * kernel image and loaded module images reside. This is required + * so x86_64 can correctly handle the %rip-relative fixups. + */ + kip->insns = module_alloc(PAGE_SIZE); + if (!kip->insns) { + kfree(kip); + return NULL; + } + INIT_HLIST_NODE(&kip->hlist); + hlist_add_head(&kip->hlist, &kprobe_insn_pages); + memset(kip->slot_used, SLOT_CLEAN, INSNS_PER_PAGE); + kip->slot_used[0] = SLOT_USED; + kip->nused = 1; + kip->ngarbage = 0; + return kip->insns; +} + +/* Return 1 if all garbages are collected, otherwise 0. */ +static int __kprobes collect_one_slot(struct kprobe_insn_page *kip, int idx) +{ + kip->slot_used[idx] = SLOT_CLEAN; + kip->nused--; + if (kip->nused == 0) { + /* + * Page is no longer in use. Free it unless + * it's the last one. We keep the last one + * 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 { + module_free(NULL, kip->insns); + kfree(kip); + } + return 1; + } + return 0; +} + +static int __kprobes collect_garbage_slots(void) +{ + struct kprobe_insn_page *kip; + struct hlist_node *pos, *next; + + /* Ensure no-one is preepmted on the garbages */ + if (check_safety() != 0) + return -EAGAIN; + + hlist_for_each_entry_safe(kip, pos, next, &kprobe_insn_pages, hlist) { + int i; + if (kip->ngarbage == 0) + continue; + kip->ngarbage = 0; /* we will collect all garbages */ + for (i = 0; i < INSNS_PER_PAGE; i++) { + if (kip->slot_used[i] == SLOT_DIRTY && + collect_one_slot(kip, i)) + break; + } + } + kprobe_garbage_slots = 0; + return 0; +} + +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) { + 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 { + collect_one_slot(kip, i); + } + break; + } + } + + if (dirty && ++kprobe_garbage_slots > INSNS_PER_PAGE) + collect_garbage_slots(); +} +#endif + +/* We have preemption disabled.. so it is safe to use __ versions */ +static inline void set_kprobe_instance(struct kprobe *kp) +{ + __get_cpu_var(kprobe_instance) = kp; +} + +static inline void reset_kprobe_instance(void) +{ + __get_cpu_var(kprobe_instance) = NULL; +} + +/* + * This routine is called either: + * - under the kprobe_mutex - during kprobe_[un]register() + * OR + * - with preemption disabled - from arch/xxx/kernel/kprobes.c + */ +struct kprobe __kprobes *get_kprobe(void *addr) +{ + struct hlist_head *head; + struct hlist_node *node; + struct kprobe *p; + + head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)]; + hlist_for_each_entry_rcu(p, node, head, hlist) { + if (p->addr == addr) + return p; + } + return NULL; +} + +/* + * Aggregate handlers for multiple kprobes support - these handlers + * take care of invoking the individual kprobe handlers on p->list + */ +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) { + set_kprobe_instance(kp); + if (kp->pre_handler(kp, regs)) + return 1; + } + reset_kprobe_instance(); + } + return 0; +} + +static void __kprobes aggr_post_handler(struct kprobe *p, struct pt_regs *regs, + unsigned long flags) +{ + struct kprobe *kp; + + list_for_each_entry_rcu(kp, &p->list, list) { + if (kp->post_handler) { + set_kprobe_instance(kp); + kp->post_handler(kp, regs, flags); + reset_kprobe_instance(); + } + } +} + +static int __kprobes aggr_fault_handler(struct kprobe *p, struct pt_regs *regs, + int trapnr) +{ + struct kprobe *cur = __get_cpu_var(kprobe_instance); + + /* + * if we faulted "during" the execution of a user specified + * probe handler, invoke just that probe's fault handler + */ + if (cur && cur->fault_handler) { + if (cur->fault_handler(cur, regs, trapnr)) + return 1; + } + return 0; +} + +static int __kprobes aggr_break_handler(struct kprobe *p, struct pt_regs *regs) +{ + struct kprobe *cur = __get_cpu_var(kprobe_instance); + int ret = 0; + + if (cur && cur->break_handler) { + if (cur->break_handler(cur, regs)) + ret = 1; + } + reset_kprobe_instance(); + return ret; +} + +/* Walks the list and increments nmissed count for multiprobe case */ +void __kprobes kprobes_inc_nmissed_count(struct kprobe *p) +{ + struct kprobe *kp; + if (p->pre_handler != aggr_pre_handler) { + p->nmissed++; + } else { + list_for_each_entry_rcu(kp, &p->list, list) + kp->nmissed++; + } + return; +} + +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); + 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); +} + +void kretprobe_hash_lock(struct task_struct *tsk, + struct hlist_head **head, unsigned long *flags) +{ + 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 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) +{ + 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 kretprobe_table_unlock(unsigned long hash, unsigned long *flags) +{ + spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash); + spin_unlock_irqrestore(hlist_lock, *flags); +} + +/* + * This function is called from finish_task_switch when task tk becomes dead, + * so that we can recycle any function-return probe instances associated + * with this task. These left over instances represent probed functions + * that have been called but will never return. + */ +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 hash, flags = 0; + + 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); + } + 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); + } +} + +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, 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 + */ +static inline void copy_kprobe(struct kprobe *old_p, struct kprobe *p) +{ + memcpy(&p->opcode, &old_p->opcode, sizeof(kprobe_opcode_t)); + memcpy(&p->ainsn, &old_p->ainsn, sizeof(struct arch_specific_insn)); +} + +/* +* Add the new probe to old_p->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) +{ + if (p->break_handler) { + if (old_p->break_handler) + return -EEXIST; + list_add_tail_rcu(&p->list, &old_p->list); + old_p->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; + return 0; +} + +/* + * Fill in the required fields of the "manager kprobe". Replace the + * earlier kprobe in the hlist with the manager kprobe + */ +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->pre_handler = aggr_pre_handler; + ap->fault_handler = aggr_fault_handler; + if (p->post_handler) + ap->post_handler = aggr_post_handler; + if (p->break_handler) + ap->break_handler = aggr_break_handler; + + INIT_LIST_HEAD(&ap->list); + list_add_rcu(&p->list, &ap->list); + + hlist_replace_rcu(&p->hlist, &ap->hlist); +} + +/* + * This is the second or subsequent kprobe at the address - handle + * the intricacies + */ +static int __kprobes register_aggr_kprobe(struct kprobe *old_p, + struct kprobe *p) +{ + int ret = 0; + struct kprobe *ap; + + if (old_p->pre_handler == aggr_pre_handler) { + copy_kprobe(old_p, p); + ret = add_new_kprobe(old_p, p); + } else { + 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; +} + +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; +} + +/* + * 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); +} + +static int __kprobes __register_kprobe(struct kprobe *p, + unsigned long called_from) +{ + int ret = 0; + struct kprobe *old_p; + struct module *probed_mod; + kprobe_opcode_t *addr; + + addr = kprobe_addr(p); + if (!addr) + return -EINVAL; + p->addr = addr; + + preempt_disable(); + if (!__kernel_text_address((unsigned long) p->addr) || + in_kprobes_functions((unsigned long) p->addr)) { + preempt_enable(); + return -EINVAL; + } + + p->mod_refcounted = 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. + */ + 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; + } + preempt_enable(); + + p->nmissed = 0; + INIT_LIST_HEAD(&p->list); + mutex_lock(&kprobe_mutex); + old_p = get_kprobe(p->addr); + if (old_p) { + ret = register_aggr_kprobe(old_p, p); + goto out; + } + + ret = arch_prepare_kprobe(p); + if (ret) + goto out; + + INIT_HLIST_NODE(&p->hlist); + hlist_add_head_rcu(&p->hlist, + &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]); + + if (kprobe_enabled) + arch_arm_kprobe(p); + +out: + mutex_unlock(&kprobe_mutex); + + if (ret && probed_mod) + module_put(probed_mod); + return ret; +} + +/* + * 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_kprobe(p->addr); + if (unlikely(!old_p)) + return -EINVAL; + + 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; + return -EINVAL; + } +valid_p: + if (old_p == p || + (old_p->pre_handler == aggr_pre_handler && + 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. + */ + if (kprobe_enabled) + arch_disarm_kprobe(p); + hlist_del_rcu(&old_p->hlist); + } else { + 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 != p) && (list_p->post_handler)) + goto noclean; + } + old_p->post_handler = NULL; + } +noclean: + list_del_rcu(&p->list); + } + return 0; +} + +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); + } + arch_remove_kprobe(p); + } +} + +static int __register_kprobes(struct kprobe **kps, int num, + unsigned long called_from) +{ + int i, ret = 0; + + if (num <= 0) + return -EINVAL; + for (i = 0; i < num; i++) { + ret = __register_kprobe(kps[i], called_from); + if (ret < 0) { + if (i > 0) + unregister_kprobes(kps, i); + break; + } + } + 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; + + 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]); +} + +static struct notifier_block kprobe_exceptions_nb = { + .notifier_call = kprobe_exceptions_notify, + .priority = 0x7fffffff /* we need to be notified first */ +}; + +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) +{ + struct jprobe *jp; + int ret = 0, i; + + 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, called_from); + } + if (ret < 0) { + if (i > 0) + unregister_jprobes(jps, i); + break; + } + } + return ret; +} + +int __kprobes register_jprobe(struct jprobe *jp) +{ + return __register_jprobes(&jp, 1, + (unsigned long)__builtin_return_address(0)); +} + +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; + + 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); + + synchronize_sched(); + for (i = 0; i < num; i++) { + if (jps[i]->kp.addr) + __unregister_kprobe_bottom(&jps[i]->kp); + } +} + +#ifdef CONFIG_KRETPROBES +/* + * This kprobe pre_handler is registered with every kretprobe. When probe + * hits it will set up the return probe. + */ +static int __kprobes pre_handler_kretprobe(struct kprobe *p, + struct pt_regs *regs) +{ + struct kretprobe *rp = container_of(p, struct kretprobe, kp); + unsigned long hash, flags = 0; + struct kretprobe_instance *ri; + + /*TODO: consider to only swap the RA after the last pre_handler fired */ + hash = hash_ptr(current, KPROBE_HASH_BITS); + spin_lock_irqsave(&rp->lock, flags); + if (!hlist_empty(&rp->free_instances)) { + ri = hlist_entry(rp->free_instances.first, + 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)) { + spin_unlock_irqrestore(&rp->lock, flags); + return 0; + } + + arch_prepare_kretprobe(ri, regs); + + /* XXX(hch): why is there no hlist_move_head? */ + 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(&rp->lock, flags); + } + return 0; +} + +static int __kprobes __register_kretprobe(struct kretprobe *rp, + unsigned long called_from) +{ + 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; + rp->kp.fault_handler = NULL; + rp->kp.break_handler = NULL; + + /* Pre-allocate memory for max kretprobe instances */ + if (rp->maxactive <= 0) { +#ifdef CONFIG_PREEMPT + rp->maxactive = max(10, 2 * NR_CPUS); +#else + rp->maxactive = NR_CPUS; +#endif + } + spin_lock_init(&rp->lock); + INIT_HLIST_HEAD(&rp->free_instances); + for (i = 0; i < rp->maxactive; i++) { + inst = kmalloc(sizeof(struct kretprobe_instance) + + rp->data_size, GFP_KERNEL); + if (inst == NULL) { + free_rp_inst(rp); + return -ENOMEM; + } + INIT_HLIST_NODE(&inst->hlist); + hlist_add_head(&inst->hlist, &rp->free_instances); + } + + rp->nmissed = 0; + /* Establish function entry probe point */ + ret = __register_kprobe(&rp->kp, called_from); + if (ret != 0) + free_rp_inst(rp); + return ret; +} + +static int __register_kretprobes(struct kretprobe **rps, int num, + unsigned long called_from) +{ + int ret = 0, i; + + if (num <= 0) + return -EINVAL; + for (i = 0; i < num; i++) { + ret = __register_kretprobe(rps[i], called_from); + if (ret < 0) { + if (i > 0) + unregister_kretprobes(rps, i); + break; + } + } + 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; + + 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]); + } + } +} + +#else /* CONFIG_KRETPROBES */ +int __kprobes register_kretprobe(struct kretprobe *rp) +{ + return -ENOSYS; +} + +int __kprobes register_kretprobes(struct kretprobe **rps, int num) +{ + return -ENOSYS; +} +void __kprobes unregister_kretprobe(struct kretprobe *rp) +{ +} + +void __kprobes unregister_kretprobes(struct kretprobe **rps, int num) +{ +} + +static int __kprobes pre_handler_kretprobe(struct kprobe *p, + struct pt_regs *regs) +{ + return 0; +} + +#endif /* CONFIG_KRETPROBES */ + +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)); + } + + /* + * 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 enabled */ + kprobe_enabled = true; + + err = arch_init_kprobes(); + if (!err) + err = register_die_notifier(&kprobe_exceptions_nb); + kprobes_initialized = (err == 0); + + if (!err) + init_test_probes(); + return err; +} + +#ifdef CONFIG_DEBUG_FS +static void __kprobes report_probe(struct seq_file *pi, struct kprobe *p, + const char *sym, int offset,char *modname) +{ + char *kprobe_type; + + if (p->pre_handler == pre_handler_kretprobe) + kprobe_type = "r"; + else if (p->pre_handler == setjmp_pre_handler) + kprobe_type = "j"; + else + kprobe_type = "k"; + if (sym) + seq_printf(pi, "%p %s %s+0x%x %s\n", p->addr, kprobe_type, + sym, offset, (modname ? modname : " ")); + else + seq_printf(pi, "%p %s %p\n", p->addr, kprobe_type, p->addr); +} + +static void __kprobes *kprobe_seq_start(struct seq_file *f, loff_t *pos) +{ + return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL; +} + +static void __kprobes *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos) +{ + (*pos)++; + if (*pos >= KPROBE_TABLE_SIZE) + return NULL; + return pos; +} + +static void __kprobes kprobe_seq_stop(struct seq_file *f, void *v) +{ + /* Nothing to do */ +} + +static int __kprobes show_kprobe_addr(struct seq_file *pi, void *v) +{ + struct hlist_head *head; + struct hlist_node *node; + struct kprobe *p, *kp; + const char *sym = NULL; + unsigned int i = *(loff_t *) v; + unsigned long offset = 0; + char *modname, namebuf[128]; + + head = &kprobe_table[i]; + preempt_disable(); + hlist_for_each_entry_rcu(p, node, head, hlist) { + sym = kallsyms_lookup((unsigned long)p->addr, NULL, + &offset, &modname, namebuf); + if (p->pre_handler == aggr_pre_handler) { + list_for_each_entry_rcu(kp, &p->list, list) + report_probe(pi, kp, sym, offset, modname); + } else + report_probe(pi, p, sym, offset, modname); + } + preempt_enable(); + return 0; +} + +static struct seq_operations kprobes_seq_ops = { + .start = kprobe_seq_start, + .next = kprobe_seq_next, + .stop = kprobe_seq_stop, + .show = show_kprobe_addr +}; + +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 = { + .open = kprobes_open, + .read = seq_read, + .llseek = seq_lseek, + .release = seq_release, +}; + +static void __kprobes enable_all_kprobes(void) +{ + struct hlist_head *head; + struct hlist_node *node; + struct kprobe *p; + unsigned int i; + + mutex_lock(&kprobe_mutex); + + /* If kprobes are already enabled, just return */ + if (kprobe_enabled) + goto already_enabled; + + 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); + } + + kprobe_enabled = true; + printk(KERN_INFO "Kprobes globally enabled\n"); + +already_enabled: + mutex_unlock(&kprobe_mutex); + return; +} + +static void __kprobes disable_all_kprobes(void) +{ + struct hlist_head *head; + struct hlist_node *node; + struct kprobe *p; + unsigned int i; + + mutex_lock(&kprobe_mutex); + + /* If kprobes are already disabled, just return */ + if (!kprobe_enabled) + goto already_disabled; + + kprobe_enabled = false; + printk(KERN_INFO "Kprobes globally disabled\n"); + 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)) + arch_disarm_kprobe(p); + } + } + + mutex_unlock(&kprobe_mutex); + /* Allow all currently running kprobes to complete */ + synchronize_sched(); + return; + +already_disabled: + mutex_unlock(&kprobe_mutex); + return; +} + +/* + * XXX: The debugfs bool file interface doesn't allow for callbacks + * when the bool state is switched. We can reuse that facility when + * available + */ +static ssize_t read_enabled_file_bool(struct file *file, + char __user *user_buf, size_t count, loff_t *ppos) +{ + char buf[3]; + + if (kprobe_enabled) + buf[0] = '1'; + else + buf[0] = '0'; + buf[1] = '\n'; + buf[2] = 0x00; + return simple_read_from_buffer(user_buf, count, ppos, buf, 2); +} + +static ssize_t write_enabled_file_bool(struct file *file, + const char __user *user_buf, size_t count, loff_t *ppos) +{ + char buf[32]; + int buf_size; + + buf_size = min(count, (sizeof(buf)-1)); + if (copy_from_user(buf, user_buf, buf_size)) + return -EFAULT; + + switch (buf[0]) { + case 'y': + case 'Y': + case '1': + enable_all_kprobes(); + break; + case 'n': + case 'N': + case '0': + disable_all_kprobes(); + break; + } + + return count; +} + +static struct file_operations fops_kp = { + .read = read_enabled_file_bool, + .write = write_enabled_file_bool, +}; + +static int __kprobes debugfs_kprobe_init(void) +{ + struct dentry *dir, *file; + unsigned int value = 1; + + dir = debugfs_create_dir("kprobes", NULL); + if (!dir) + return -ENOMEM; + + file = debugfs_create_file("list", 0444, dir, NULL, + &debugfs_kprobes_operations); + if (!file) { + debugfs_remove(dir); + return -ENOMEM; + } + + file = debugfs_create_file("enabled", 0600, dir, + &value, &fops_kp); + if (!file) { + debugfs_remove(dir); + return -ENOMEM; + } + + return 0; +} + +late_initcall(debugfs_kprobe_init); +#endif /* CONFIG_DEBUG_FS */ + +module_init(init_kprobes); + +EXPORT_SYMBOL_GPL(register_kprobe); +EXPORT_SYMBOL_GPL(unregister_kprobe); +EXPORT_SYMBOL_GPL(register_kprobes); +EXPORT_SYMBOL_GPL(unregister_kprobes); +EXPORT_SYMBOL_GPL(register_jprobe); +EXPORT_SYMBOL_GPL(unregister_jprobe); +EXPORT_SYMBOL_GPL(register_jprobes); +EXPORT_SYMBOL_GPL(unregister_jprobes); +EXPORT_SYMBOL_GPL(jprobe_return); +EXPORT_SYMBOL_GPL(register_kretprobe); +EXPORT_SYMBOL_GPL(unregister_kretprobe); +EXPORT_SYMBOL_GPL(register_kretprobes); +EXPORT_SYMBOL_GPL(unregister_kretprobes); |
