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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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SPDX-License-Identifier: GPL-2.0-or-later/* * Kernel Probes (KProbes) * * 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. */
#define pr_fmt(fmt) "kprobes: " fmt
#include <linux/kprobes.h>#include <linux/hash.h>#include <linux/init.h>#include <linux/slab.h>#include <linux/stddef.h>#include <linux/export.h>#include <linux/kallsyms.h>#include <linux/freezer.h>#include <linux/seq_file.h>#include <linux/debugfs.h>#include <linux/sysctl.h>#include <linux/kdebug.h>#include <linux/kthread.h>#include <linux/memory.h>#include <linux/ftrace.h>#include <linux/cpu.h>#include <linux/jump_label.h>#include <linux/static_call.h>#include <linux/perf_event.h>#include <linux/execmem.h>#include <linux/cleanup.h>#include <linux/wait.h>
#include <asm/sections.h>#include <asm/cacheflush.h>#include <asm/errno.h>#include <linux/uaccess.h>
#define KPROBE_HASH_BITS 6#define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS)
#if !defined(CONFIG_OPTPROBES) || !defined(CONFIG_SYSCTL)#define kprobe_sysctls_init() do { } while (0)#endif
static int kprobes_initialized;/* kprobe_table can be accessed by * - Normal hlist traversal and RCU add/del under 'kprobe_mutex' is held. * Or * - RCU hlist traversal under disabling preempt (breakpoint handlers) */static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
/* NOTE: change this value only with 'kprobe_mutex' held */static bool kprobes_all_disarmed;
/* This protects 'kprobe_table' and 'optimizing_list' */static DEFINE_MUTEX(kprobe_mutex);static DEFINE_PER_CPU(struct kprobe *, kprobe_instance);
kprobe_opcode_t * __weak kprobe_lookup_name(const char *name, unsigned int __unused){ return ((kprobe_opcode_t *)(kallsyms_lookup_name(name)));}
/* * Blacklist -- list of 'struct kprobe_blacklist_entry' to store info where * kprobes can not probe. */static LIST_HEAD(kprobe_blacklist);
#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 */struct kprobe_insn_page { struct list_head list; kprobe_opcode_t *insns; /* Page of instruction slots */ struct kprobe_insn_cache *cache; int nused; int ngarbage; char slot_used[];};
static int slots_per_page(struct kprobe_insn_cache *c){ return PAGE_SIZE/(c->insn_size * sizeof(kprobe_opcode_t));}
enum kprobe_slot_state { SLOT_CLEAN = 0, SLOT_DIRTY = 1, SLOT_USED = 2,};
void __weak *alloc_insn_page(void){ /* * Use execmem_alloc() so this page is within +/- 2GB of where the * kernel image and loaded module images reside. This is required * for most of the architectures. * (e.g. x86-64 needs this to handle the %rip-relative fixups.) */ return execmem_alloc(EXECMEM_KPROBES, PAGE_SIZE);}
static void free_insn_page(void *page){ execmem_free(page);}
struct kprobe_insn_cache kprobe_insn_slots = { .mutex = __MUTEX_INITIALIZER(kprobe_insn_slots.mutex), .alloc = alloc_insn_page, .free = free_insn_page, .sym = KPROBE_INSN_PAGE_SYM, .pages = LIST_HEAD_INIT(kprobe_insn_slots.pages), .insn_size = MAX_INSN_SIZE, .nr_garbage = 0,};static int collect_garbage_slots(struct kprobe_insn_cache *c);
/** * __get_insn_slot - Find a slot on an executable page for an instruction. * @c: Pointer to kprobe instruction cache * * Description: Locates available slot on existing executable pages, * allocates an executable page if there's no room on existing ones. * Return: Pointer to instruction slot on success, NULL on failure. */kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c){ struct kprobe_insn_page *kip;
/* Since the slot array is not protected by rcu, we need a mutex */ guard(mutex)(&c->mutex); do { guard(rcu)(); list_for_each_entry_rcu(kip, &c->pages, list) { if (kip->nused < slots_per_page(c)) { int i;
for (i = 0; i < slots_per_page(c); i++) { if (kip->slot_used[i] == SLOT_CLEAN) { kip->slot_used[i] = SLOT_USED; kip->nused++; return kip->insns + (i * c->insn_size); } } /* kip->nused is broken. Fix it. */ kip->nused = slots_per_page(c); WARN_ON(1); } } /* If there are any garbage slots, collect it and try again. */ } while (c->nr_garbage && collect_garbage_slots(c) == 0);
/* All out of space. Need to allocate a new page. */ kip = kmalloc_flex(*kip, slot_used, slots_per_page(c)); if (!kip) return NULL;
kip->insns = c->alloc(); if (!kip->insns) { kfree(kip); return NULL; } INIT_LIST_HEAD(&kip->list); memset(kip->slot_used, SLOT_CLEAN, slots_per_page(c)); kip->slot_used[0] = SLOT_USED; kip->nused = 1; kip->ngarbage = 0; kip->cache = c; list_add_rcu(&kip->list, &c->pages);
/* Record the perf ksymbol register event after adding the page */ perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_OOL, (unsigned long)kip->insns, PAGE_SIZE, false, c->sym);
return kip->insns;}
/* Return true if all garbages are collected, otherwise false. */static bool collect_one_slot(struct kprobe_insn_page *kip, int idx){ kip->slot_used[idx] = SLOT_CLEAN; kip->nused--; if (kip->nused != 0) return false;
/* * 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. */ if (!list_is_singular(&kip->list)) { /* * Record perf ksymbol unregister event before removing * the page. */ perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_OOL, (unsigned long)kip->insns, PAGE_SIZE, true, kip->cache->sym); list_del_rcu(&kip->list); synchronize_rcu(); kip->cache->free(kip->insns); kfree(kip); } return true;}
static int collect_garbage_slots(struct kprobe_insn_cache *c){ struct kprobe_insn_page *kip, *next;
/* Ensure no-one is interrupted on the garbages */ synchronize_rcu();
list_for_each_entry_safe(kip, next, &c->pages, list) { int i;
if (kip->ngarbage == 0) continue; kip->ngarbage = 0; /* we will collect all garbages */ for (i = 0; i < slots_per_page(c); i++) { if (kip->slot_used[i] == SLOT_DIRTY && collect_one_slot(kip, i)) break; } } c->nr_garbage = 0; return 0;}
static long __find_insn_page(struct kprobe_insn_cache *c, kprobe_opcode_t *slot, struct kprobe_insn_page **pkip){ struct kprobe_insn_page *kip = NULL; long idx;
guard(rcu)(); list_for_each_entry_rcu(kip, &c->pages, list) { idx = ((long)slot - (long)kip->insns) / (c->insn_size * sizeof(kprobe_opcode_t)); if (idx >= 0 && idx < slots_per_page(c)) { *pkip = kip; return idx; } } /* Could not find this slot. */ WARN_ON(1); *pkip = NULL; return -1;}
void __free_insn_slot(struct kprobe_insn_cache *c, kprobe_opcode_t *slot, int dirty){ struct kprobe_insn_page *kip = NULL; long idx;
guard(mutex)(&c->mutex); idx = __find_insn_page(c, slot, &kip); /* Mark and sweep: this may sleep */ if (kip) { /* Check double free */ WARN_ON(kip->slot_used[idx] != SLOT_USED); if (dirty) { kip->slot_used[idx] = SLOT_DIRTY; kip->ngarbage++; if (++c->nr_garbage > slots_per_page(c)) collect_garbage_slots(c); } else { collect_one_slot(kip, idx); } }}
/* * Check given address is on the page of kprobe instruction slots. * This will be used for checking whether the address on a stack * is on a text area or not. */bool __is_insn_slot_addr(struct kprobe_insn_cache *c, unsigned long addr){ struct kprobe_insn_page *kip; bool ret = false;
rcu_read_lock(); list_for_each_entry_rcu(kip, &c->pages, list) { if (addr >= (unsigned long)kip->insns && addr < (unsigned long)kip->insns + PAGE_SIZE) { ret = true; break; } } rcu_read_unlock();
return ret;}
int kprobe_cache_get_kallsym(struct kprobe_insn_cache *c, unsigned int *symnum, unsigned long *value, char *type, char *sym){ struct kprobe_insn_page *kip; int ret = -ERANGE;
rcu_read_lock(); list_for_each_entry_rcu(kip, &c->pages, list) { if ((*symnum)--) continue; strscpy(sym, c->sym, KSYM_NAME_LEN); *type = 't'; *value = (unsigned long)kip->insns; ret = 0; break; } rcu_read_unlock();
return ret;}
#ifdef CONFIG_OPTPROBESvoid __weak *alloc_optinsn_page(void){ return alloc_insn_page();}
void __weak free_optinsn_page(void *page){ free_insn_page(page);}
/* For optimized_kprobe buffer */struct kprobe_insn_cache kprobe_optinsn_slots = { .mutex = __MUTEX_INITIALIZER(kprobe_optinsn_slots.mutex), .alloc = alloc_optinsn_page, .free = free_optinsn_page, .sym = KPROBE_OPTINSN_PAGE_SYM, .pages = LIST_HEAD_INIT(kprobe_optinsn_slots.pages), /* .insn_size is initialized later */ .nr_garbage = 0,};#endif /* CONFIG_OPTPROBES */#endif /* __ARCH_WANT_KPROBES_INSN_SLOT */
/* We have preemption disabled.. so it is safe to use __ versions */static inline void set_kprobe_instance(struct kprobe *kp){ __this_cpu_write(kprobe_instance, kp);}
static inline void reset_kprobe_instance(void){ __this_cpu_write(kprobe_instance, NULL);}
/* * This routine is called either: * - under the 'kprobe_mutex' - during kprobe_[un]register(). * OR * - with preemption disabled - from architecture specific code. */struct kprobe *get_kprobe(void *addr){ struct hlist_head *head; struct kprobe *p;
head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)]; hlist_for_each_entry_rcu(p, head, hlist, lockdep_is_held(&kprobe_mutex)) { if (p->addr == addr) return p; }
return NULL;}NOKPROBE_SYMBOL(get_kprobe);
static int aggr_pre_handler(struct kprobe *p, struct pt_regs *regs);
/* Return true if 'p' is an aggregator */static inline bool kprobe_aggrprobe(struct kprobe *p){ return p->pre_handler == aggr_pre_handler;}
/* Return true if 'p' is unused */static inline bool kprobe_unused(struct kprobe *p){ return kprobe_aggrprobe(p) && kprobe_disabled(p) && list_empty(&p->list);}
/* Keep all fields in the kprobe consistent. */static inline void copy_kprobe(struct kprobe *ap, struct kprobe *p){ memcpy(&p->opcode, &ap->opcode, sizeof(kprobe_opcode_t)); memcpy(&p->ainsn, &ap->ainsn, sizeof(struct arch_specific_insn));}
#ifdef CONFIG_OPTPROBES/* NOTE: This is protected by 'kprobe_mutex'. */static bool kprobes_allow_optimization;
/* * Call all 'kprobe::pre_handler' on the list, but ignores its return value. * This must be called from arch-dep optimized caller. */void opt_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 && likely(!kprobe_disabled(kp))) { set_kprobe_instance(kp); kp->pre_handler(kp, regs); } reset_kprobe_instance(); }}NOKPROBE_SYMBOL(opt_pre_handler);
/* Free optimized instructions and optimized_kprobe */static void free_aggr_kprobe(struct kprobe *p){ struct optimized_kprobe *op;
op = container_of(p, struct optimized_kprobe, kp); arch_remove_optimized_kprobe(op); arch_remove_kprobe(p); kfree(op);}
/* Return true if the kprobe is ready for optimization. */static inline int kprobe_optready(struct kprobe *p){ struct optimized_kprobe *op;
if (kprobe_aggrprobe(p)) { op = container_of(p, struct optimized_kprobe, kp); return arch_prepared_optinsn(&op->optinsn); }
return 0;}
/* Return true if the kprobe is disarmed. Note: p must be on hash list */bool kprobe_disarmed(struct kprobe *p){ struct optimized_kprobe *op;
/* If kprobe is not aggr/opt probe, just return kprobe is disabled */ if (!kprobe_aggrprobe(p)) return kprobe_disabled(p);
op = container_of(p, struct optimized_kprobe, kp);
return kprobe_disabled(p) && list_empty(&op->list);}
/* Return true if the probe is queued on (un)optimizing lists */static bool kprobe_queued(struct kprobe *p){ struct optimized_kprobe *op;
if (kprobe_aggrprobe(p)) { op = container_of(p, struct optimized_kprobe, kp); if (!list_empty(&op->list)) return true; } return false;}
/* * Return an optimized kprobe whose optimizing code replaces * instructions including 'addr' (exclude breakpoint). */static struct kprobe *get_optimized_kprobe(kprobe_opcode_t *addr){ int i; struct kprobe *p = NULL; struct optimized_kprobe *op;
/* Don't check i == 0, since that is a breakpoint case. */ for (i = 1; !p && i < MAX_OPTIMIZED_LENGTH / sizeof(kprobe_opcode_t); i++) p = get_kprobe(addr - i);
if (p && kprobe_optready(p)) { op = container_of(p, struct optimized_kprobe, kp); if (arch_within_optimized_kprobe(op, addr)) return p; }
return NULL;}
/* Optimization staging list, protected by 'kprobe_mutex' */static LIST_HEAD(optimizing_list);static LIST_HEAD(unoptimizing_list);static LIST_HEAD(freeing_list);
static void optimize_kprobe(struct kprobe *p);static struct task_struct *kprobe_optimizer_task;static wait_queue_head_t kprobe_optimizer_wait;static atomic_t optimizer_state;enum { OPTIMIZER_ST_IDLE = 0, OPTIMIZER_ST_KICKED = 1, OPTIMIZER_ST_FLUSHING = 2,};
static DECLARE_COMPLETION(optimizer_completion);
#define OPTIMIZE_DELAY 5
/* * Optimize (replace a breakpoint with a jump) kprobes listed on * 'optimizing_list'. */static void do_optimize_kprobes(void){ lockdep_assert_held(&text_mutex); /* * The optimization/unoptimization refers 'online_cpus' via * stop_machine() and cpu-hotplug modifies the 'online_cpus'. * And same time, 'text_mutex' will be held in cpu-hotplug and here. * This combination can cause a deadlock (cpu-hotplug tries to lock * 'text_mutex' but stop_machine() can not be done because * the 'online_cpus' has been changed) * To avoid this deadlock, caller must have locked cpu-hotplug * for preventing cpu-hotplug outside of 'text_mutex' locking. */ lockdep_assert_cpus_held();
/* Optimization never be done when disarmed */ if (kprobes_all_disarmed || !kprobes_allow_optimization || list_empty(&optimizing_list)) return;
arch_optimize_kprobes(&optimizing_list);}
/* * Unoptimize (replace a jump with a breakpoint and remove the breakpoint * if need) kprobes listed on 'unoptimizing_list'. */static void do_unoptimize_kprobes(void){ struct optimized_kprobe *op, *tmp;
lockdep_assert_held(&text_mutex); /* See comment in do_optimize_kprobes() */ lockdep_assert_cpus_held();
if (!list_empty(&unoptimizing_list)) arch_unoptimize_kprobes(&unoptimizing_list, &freeing_list);
/* Loop on 'freeing_list' for disarming and removing from kprobe hash list */ list_for_each_entry_safe(op, tmp, &freeing_list, list) { /* Switching from detour code to origin */ op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED; /* Disarm probes if marked disabled and not gone */ if (kprobe_disabled(&op->kp) && !kprobe_gone(&op->kp)) arch_disarm_kprobe(&op->kp); if (kprobe_unused(&op->kp)) { /* * Remove unused probes from hash list. After waiting * for synchronization, these probes are reclaimed. * (reclaiming is done by do_free_cleaned_kprobes().) */ hlist_del_rcu(&op->kp.hlist); } else list_del_init(&op->list); }}
/* Reclaim all kprobes on the 'freeing_list' */static void do_free_cleaned_kprobes(void){ struct optimized_kprobe *op, *tmp;
list_for_each_entry_safe(op, tmp, &freeing_list, list) { list_del_init(&op->list); if (WARN_ON_ONCE(!kprobe_unused(&op->kp))) { /* * This must not happen, but if there is a kprobe * still in use, keep it on kprobes hash list. */ continue; }
/* * The aggregator was holding back another probe while it sat on the * unoptimizing/freeing lists. Now that the aggregator has been fully * reverted we can safely retry the optimization of that sibling. */
struct kprobe *_p = get_optimized_kprobe(op->kp.addr); if (unlikely(_p)) optimize_kprobe(_p);
free_aggr_kprobe(&op->kp); }}
static void kick_kprobe_optimizer(void);
/* Kprobe jump optimizer */static void kprobe_optimizer(void){ guard(mutex)(&kprobe_mutex);
scoped_guard(cpus_read_lock) { guard(mutex)(&text_mutex);
/* * Step 1: Unoptimize kprobes and collect cleaned (unused and disarmed) * kprobes before waiting for quiesence period. */ do_unoptimize_kprobes();
/* * Step 2: Wait for quiesence period to ensure all potentially * preempted tasks to have normally scheduled. Because optprobe * may modify multiple instructions, there is a chance that Nth * instruction is preempted. In that case, such tasks can return * to 2nd-Nth byte of jump instruction. This wait is for avoiding it. * Note that on non-preemptive kernel, this is transparently converted * to synchronoze_sched() to wait for all interrupts to have completed. */ synchronize_rcu_tasks();
/* Step 3: Optimize kprobes after quiesence period */ do_optimize_kprobes();
/* Step 4: Free cleaned kprobes after quiesence period */ do_free_cleaned_kprobes(); }
/* Step 5: Kick optimizer again if needed. But if there is a flush requested, */ if (completion_done(&optimizer_completion)) complete(&optimizer_completion);
if (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list)) kick_kprobe_optimizer(); /*normal kick*/}
static int kprobe_optimizer_thread(void *data){ while (!kthread_should_stop()) { /* To avoid hung_task, wait in interruptible state. */ wait_event_interruptible(kprobe_optimizer_wait, atomic_read(&optimizer_state) != OPTIMIZER_ST_IDLE || kthread_should_stop());
if (kthread_should_stop()) break;
/* * If it was a normal kick, wait for OPTIMIZE_DELAY. * This wait can be interrupted by a flush request. */ if (atomic_read(&optimizer_state) == 1) wait_event_interruptible_timeout( kprobe_optimizer_wait, atomic_read(&optimizer_state) == OPTIMIZER_ST_FLUSHING || kthread_should_stop(), OPTIMIZE_DELAY);
if (kthread_should_stop()) break;
atomic_set(&optimizer_state, OPTIMIZER_ST_IDLE);
kprobe_optimizer(); } return 0;}
/* Start optimizer after OPTIMIZE_DELAY passed */static void kick_kprobe_optimizer(void){ lockdep_assert_held(&kprobe_mutex); if (atomic_cmpxchg(&optimizer_state, OPTIMIZER_ST_IDLE, OPTIMIZER_ST_KICKED) == OPTIMIZER_ST_IDLE) wake_up(&kprobe_optimizer_wait);}
static void wait_for_kprobe_optimizer_locked(void){ lockdep_assert_held(&kprobe_mutex);
while (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list)) { init_completion(&optimizer_completion); /* * Set state to OPTIMIZER_ST_FLUSHING and wake up the thread if it's * idle. If it's already kicked, it will see the state change. */ if (atomic_xchg_acquire(&optimizer_state, OPTIMIZER_ST_FLUSHING) != OPTIMIZER_ST_FLUSHING) wake_up(&kprobe_optimizer_wait);
mutex_unlock(&kprobe_mutex); wait_for_completion(&optimizer_completion); mutex_lock(&kprobe_mutex); }}
/* Wait for completing optimization and unoptimization */void wait_for_kprobe_optimizer(void){ guard(mutex)(&kprobe_mutex);
wait_for_kprobe_optimizer_locked();}
bool optprobe_queued_unopt(struct optimized_kprobe *op){ struct optimized_kprobe *_op;
list_for_each_entry(_op, &unoptimizing_list, list) { if (op == _op) return true; }
return false;}
/* Optimize kprobe if p is ready to be optimized */static void optimize_kprobe(struct kprobe *p){ struct optimized_kprobe *op;
/* Check if the kprobe is disabled or not ready for optimization. */ if (!kprobe_optready(p) || !kprobes_allow_optimization || (kprobe_disabled(p) || kprobes_all_disarmed)) return;
/* kprobes with 'post_handler' can not be optimized */ if (p->post_handler) return;
op = container_of(p, struct optimized_kprobe, kp);
/* Check there is no other kprobes at the optimized instructions */ if (arch_check_optimized_kprobe(op) < 0) return;
/* Check if it is already optimized. */ if (op->kp.flags & KPROBE_FLAG_OPTIMIZED) { if (optprobe_queued_unopt(op)) { /* This is under unoptimizing. Just dequeue the probe */ list_del_init(&op->list); } return; } op->kp.flags |= KPROBE_FLAG_OPTIMIZED;
/* * On the 'unoptimizing_list' and 'optimizing_list', * 'op' must have OPTIMIZED flag */ if (WARN_ON_ONCE(!list_empty(&op->list))) return;
list_add(&op->list, &optimizing_list); kick_kprobe_optimizer();}
/* Short cut to direct unoptimizing */static void force_unoptimize_kprobe(struct optimized_kprobe *op){ lockdep_assert_cpus_held(); arch_unoptimize_kprobe(op); op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;}
/* Unoptimize a kprobe if p is optimized */static void unoptimize_kprobe(struct kprobe *p, bool force){ struct optimized_kprobe *op;
if (!kprobe_aggrprobe(p) || kprobe_disarmed(p)) return; /* This is not an optprobe nor optimized */
op = container_of(p, struct optimized_kprobe, kp); if (!kprobe_optimized(p)) return;
if (!list_empty(&op->list)) { if (optprobe_queued_unopt(op)) { /* Queued in unoptimizing queue */ if (force) { /* * Forcibly unoptimize the kprobe here, and queue it * in the freeing list for release afterwards. */ force_unoptimize_kprobe(op); list_move(&op->list, &freeing_list); } } else { /* Dequeue from the optimizing queue */ list_del_init(&op->list); op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED; } return; }
/* Optimized kprobe case */ if (force) { /* Forcibly update the code: this is a special case */ force_unoptimize_kprobe(op); } else { list_add(&op->list, &unoptimizing_list); kick_kprobe_optimizer(); }}
/* Cancel unoptimizing for reusing */static int reuse_unused_kprobe(struct kprobe *ap){ struct optimized_kprobe *op;
/* * Unused kprobe MUST be on the way of delayed unoptimizing (means * there is still a relative jump) and disabled. */ op = container_of(ap, struct optimized_kprobe, kp); WARN_ON_ONCE(list_empty(&op->list)); /* Enable the probe again */ ap->flags &= ~KPROBE_FLAG_DISABLED; /* Optimize it again. (remove from 'op->list') */ if (!kprobe_optready(ap)) return -EINVAL;
optimize_kprobe(ap); return 0;}
/* Remove optimized instructions */static void kill_optimized_kprobe(struct kprobe *p){ struct optimized_kprobe *op;
op = container_of(p, struct optimized_kprobe, kp); if (!list_empty(&op->list)) /* Dequeue from the (un)optimization queue */ list_del_init(&op->list); op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
if (kprobe_unused(p)) { /* * Unused kprobe is on unoptimizing or freeing list. We move it * to freeing_list and let the kprobe_optimizer() remove it from * the kprobe hash list and free it. */ if (optprobe_queued_unopt(op)) list_move(&op->list, &freeing_list); }
/* Don't touch the code, because it is already freed. */ arch_remove_optimized_kprobe(op);}
static inlinevoid __prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p){ if (!kprobe_ftrace(p)) arch_prepare_optimized_kprobe(op, p);}
/* Try to prepare optimized instructions */static void prepare_optimized_kprobe(struct kprobe *p){ struct optimized_kprobe *op;
op = container_of(p, struct optimized_kprobe, kp); __prepare_optimized_kprobe(op, p);}
/* Allocate new optimized_kprobe and try to prepare optimized instructions. */static struct kprobe *alloc_aggr_kprobe(struct kprobe *p){ struct optimized_kprobe *op;
op = kzalloc_obj(struct optimized_kprobe); if (!op) return NULL;
INIT_LIST_HEAD(&op->list); op->kp.addr = p->addr; __prepare_optimized_kprobe(op, p);
return &op->kp;}
static void init_aggr_kprobe(struct kprobe *ap, struct kprobe *p);
/* * Prepare an optimized_kprobe and optimize it. * NOTE: 'p' must be a normal registered kprobe. */static void try_to_optimize_kprobe(struct kprobe *p){ struct kprobe *ap; struct optimized_kprobe *op;
/* Impossible to optimize ftrace-based kprobe. */ if (kprobe_ftrace(p)) return;
/* For preparing optimization, jump_label_text_reserved() is called. */ guard(cpus_read_lock)(); guard(jump_label_lock)(); guard(mutex)(&text_mutex);
ap = alloc_aggr_kprobe(p); if (!ap) return;
op = container_of(ap, struct optimized_kprobe, kp); if (!arch_prepared_optinsn(&op->optinsn)) { /* If failed to setup optimizing, fallback to kprobe. */ arch_remove_optimized_kprobe(op); kfree(op); return; }
init_aggr_kprobe(ap, p); optimize_kprobe(ap); /* This just kicks optimizer thread. */}
static void optimize_all_kprobes(void){ struct hlist_head *head; struct kprobe *p; unsigned int i;
guard(mutex)(&kprobe_mutex); /* If optimization is already allowed, just return. */ if (kprobes_allow_optimization) return;
cpus_read_lock(); kprobes_allow_optimization = true; for (i = 0; i < KPROBE_TABLE_SIZE; i++) { head = &kprobe_table[i]; hlist_for_each_entry(p, head, hlist) if (!kprobe_disabled(p)) optimize_kprobe(p); } cpus_read_unlock(); pr_info("kprobe jump-optimization is enabled. All kprobes are optimized if possible.\n");}
#ifdef CONFIG_SYSCTLstatic void unoptimize_all_kprobes(void){ struct hlist_head *head; struct kprobe *p; unsigned int i;
guard(mutex)(&kprobe_mutex); /* If optimization is already prohibited, just return. */ if (!kprobes_allow_optimization) return;
cpus_read_lock(); kprobes_allow_optimization = false; for (i = 0; i < KPROBE_TABLE_SIZE; i++) { head = &kprobe_table[i]; hlist_for_each_entry(p, head, hlist) { if (!kprobe_disabled(p)) unoptimize_kprobe(p, false); } } cpus_read_unlock(); /* Wait for unoptimizing completion. */ wait_for_kprobe_optimizer_locked(); pr_info("kprobe jump-optimization is disabled. All kprobes are based on software breakpoint.\n");}
static DEFINE_MUTEX(kprobe_sysctl_mutex);static int sysctl_kprobes_optimization;static int proc_kprobes_optimization_handler(const struct ctl_table *table, int write, void *buffer, size_t *length, loff_t *ppos){ int ret;
guard(mutex)(&kprobe_sysctl_mutex); sysctl_kprobes_optimization = kprobes_allow_optimization ? 1 : 0; ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
if (sysctl_kprobes_optimization) optimize_all_kprobes(); else unoptimize_all_kprobes();
return ret;}
static const struct ctl_table kprobe_sysctls[] = { { .procname = "kprobes-optimization", .data = &sysctl_kprobes_optimization, .maxlen = sizeof(int), .mode = 0644, .proc_handler = proc_kprobes_optimization_handler, .extra1 = SYSCTL_ZERO, .extra2 = SYSCTL_ONE, },};
static void __init kprobe_sysctls_init(void){ register_sysctl_init("debug", kprobe_sysctls);}#endif /* CONFIG_SYSCTL */
/* Put a breakpoint for a probe. */static void __arm_kprobe(struct kprobe *p){ struct kprobe *_p;
lockdep_assert_held(&text_mutex);
/* Find the overlapping optimized kprobes. */ _p = get_optimized_kprobe(p->addr); if (unlikely(_p)) /* Fallback to unoptimized kprobe */ unoptimize_kprobe(_p, true);
arch_arm_kprobe(p); optimize_kprobe(p); /* Try to optimize (add kprobe to a list) */}
/* Remove the breakpoint of a probe. */static void __disarm_kprobe(struct kprobe *p, bool reopt){ struct kprobe *_p;
lockdep_assert_held(&text_mutex);
/* Try to unoptimize */ unoptimize_kprobe(p, kprobes_all_disarmed);
if (!kprobe_queued(p)) { arch_disarm_kprobe(p); /* If another kprobe was blocked, re-optimize it. */ _p = get_optimized_kprobe(p->addr); if (unlikely(_p) && reopt) optimize_kprobe(_p); }}
static void __init init_optprobe(void){#ifdef __ARCH_WANT_KPROBES_INSN_SLOT /* Init 'kprobe_optinsn_slots' for allocation */ kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE;#endif
init_waitqueue_head(&kprobe_optimizer_wait); atomic_set(&optimizer_state, OPTIMIZER_ST_IDLE); kprobe_optimizer_task = kthread_run(kprobe_optimizer_thread, NULL, "kprobe-optimizer");}#else /* !CONFIG_OPTPROBES */
#define init_optprobe() do {} while (0)#define optimize_kprobe(p) do {} while (0)#define unoptimize_kprobe(p, f) do {} while (0)#define kill_optimized_kprobe(p) do {} while (0)#define prepare_optimized_kprobe(p) do {} while (0)#define try_to_optimize_kprobe(p) do {} while (0)#define __arm_kprobe(p) arch_arm_kprobe(p)#define __disarm_kprobe(p, o) arch_disarm_kprobe(p)#define kprobe_disarmed(p) kprobe_disabled(p)#define wait_for_kprobe_optimizer_locked() \ lockdep_assert_held(&kprobe_mutex)
static int reuse_unused_kprobe(struct kprobe *ap){ /* * If the optimized kprobe is NOT supported, the aggr kprobe is * released at the same time that the last aggregated kprobe is * unregistered. * Thus there should be no chance to reuse unused kprobe. */ WARN_ON_ONCE(1); return -EINVAL;}
static void free_aggr_kprobe(struct kprobe *p){ arch_remove_kprobe(p); kfree(p);}
static struct kprobe *alloc_aggr_kprobe(struct kprobe *p){ return kzalloc_obj(struct kprobe);}#endif /* CONFIG_OPTPROBES */
#ifdef CONFIG_KPROBES_ON_FTRACEstatic struct ftrace_ops kprobe_ftrace_ops __read_mostly = { .func = kprobe_ftrace_handler, .flags = FTRACE_OPS_FL_SAVE_REGS,};
static struct ftrace_ops kprobe_ipmodify_ops __read_mostly = { .func = kprobe_ftrace_handler, .flags = FTRACE_OPS_FL_SAVE_REGS | FTRACE_OPS_FL_IPMODIFY,};
static int kprobe_ipmodify_enabled;static int kprobe_ftrace_enabled;bool kprobe_ftrace_disabled;
static int __arm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops, int *cnt){ int ret;
lockdep_assert_held(&kprobe_mutex);
ret = ftrace_set_filter_ip(ops, (unsigned long)p->addr, 0, 0); if (ret < 0) return ret;
if (*cnt == 0) { ret = register_ftrace_function(ops); if (ret < 0) { /* * At this point, sinec ops is not registered, we should be sefe from * registering empty filter. */ ftrace_set_filter_ip(ops, (unsigned long)p->addr, 1, 0); return ret; } }
(*cnt)++; return ret;}
static int arm_kprobe_ftrace(struct kprobe *p){ bool ipmodify = (p->post_handler != NULL);
return __arm_kprobe_ftrace(p, ipmodify ? &kprobe_ipmodify_ops : &kprobe_ftrace_ops, ipmodify ? &kprobe_ipmodify_enabled : &kprobe_ftrace_enabled);}
static int __disarm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops, int *cnt){ int ret;
lockdep_assert_held(&kprobe_mutex); if (unlikely(kprobe_ftrace_disabled)) { /* Now ftrace is disabled forever, disarm is already done. */ return 0; }
if (*cnt == 1) { ret = unregister_ftrace_function(ops); if (WARN(ret < 0, "Failed to unregister kprobe-ftrace (error %d)\n", ret)) return ret; }
(*cnt)--;
ret = ftrace_set_filter_ip(ops, (unsigned long)p->addr, 1, 0); WARN_ONCE(ret < 0, "Failed to disarm kprobe-ftrace at %pS (error %d)\n", p->addr, ret); return ret;}
static int disarm_kprobe_ftrace(struct kprobe *p){ bool ipmodify = (p->post_handler != NULL);
return __disarm_kprobe_ftrace(p, ipmodify ? &kprobe_ipmodify_ops : &kprobe_ftrace_ops, ipmodify ? &kprobe_ipmodify_enabled : &kprobe_ftrace_enabled);}
void kprobe_ftrace_kill(void){ kprobe_ftrace_disabled = true;}#else /* !CONFIG_KPROBES_ON_FTRACE */static inline int arm_kprobe_ftrace(struct kprobe *p){ return -ENODEV;}
static inline int disarm_kprobe_ftrace(struct kprobe *p){ return -ENODEV;}#endif
static int prepare_kprobe(struct kprobe *p){ /* Must ensure p->addr is really on ftrace */ if (kprobe_ftrace(p)) return arch_prepare_kprobe_ftrace(p);
return arch_prepare_kprobe(p);}
static int arm_kprobe(struct kprobe *kp){ if (unlikely(kprobe_ftrace(kp))) return arm_kprobe_ftrace(kp);
guard(cpus_read_lock)(); guard(mutex)(&text_mutex); __arm_kprobe(kp); return 0;}
static int disarm_kprobe(struct kprobe *kp, bool reopt){ if (unlikely(kprobe_ftrace(kp))) return disarm_kprobe_ftrace(kp);
guard(cpus_read_lock)(); guard(mutex)(&text_mutex); __disarm_kprobe(kp, reopt); return 0;}
/* * Aggregate handlers for multiple kprobes support - these handlers * take care of invoking the individual kprobe handlers on p->list */static int 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 && likely(!kprobe_disabled(kp))) { set_kprobe_instance(kp); if (kp->pre_handler(kp, regs)) return 1; } reset_kprobe_instance(); } return 0;}NOKPROBE_SYMBOL(aggr_pre_handler);
static void 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 && likely(!kprobe_disabled(kp))) { set_kprobe_instance(kp); kp->post_handler(kp, regs, flags); reset_kprobe_instance(); } }}NOKPROBE_SYMBOL(aggr_post_handler);
/* Walks the list and increments 'nmissed' if 'p' has child probes. */void kprobes_inc_nmissed_count(struct kprobe *p){ struct kprobe *kp;
if (!kprobe_aggrprobe(p)) { p->nmissed++; } else { list_for_each_entry_rcu(kp, &p->list, list) kp->nmissed++; }}NOKPROBE_SYMBOL(kprobes_inc_nmissed_count);
static struct kprobe kprobe_busy = { .addr = (void *) get_kprobe,};
void kprobe_busy_begin(void){ struct kprobe_ctlblk *kcb;
preempt_disable(); __this_cpu_write(current_kprobe, &kprobe_busy); kcb = get_kprobe_ctlblk(); kcb->kprobe_status = KPROBE_HIT_ACTIVE;}
void kprobe_busy_end(void){ __this_cpu_write(current_kprobe, NULL); preempt_enable();}
/* Add the new probe to 'ap->list'. */static int add_new_kprobe(struct kprobe *ap, struct kprobe *p){ if (p->post_handler) unoptimize_kprobe(ap, true); /* Fall back to normal kprobe */
list_add_rcu(&p->list, &ap->list); if (p->post_handler && !ap->post_handler) ap->post_handler = aggr_post_handler;
return 0;}
/* * Fill in the required fields of the aggregator kprobe. Replace the * earlier kprobe in the hlist with the aggregator kprobe. */static void init_aggr_kprobe(struct kprobe *ap, struct kprobe *p){ /* Copy the insn slot of 'p' to 'ap'. */ copy_kprobe(p, ap); flush_insn_slot(ap); ap->addr = p->addr; ap->flags = p->flags & ~KPROBE_FLAG_OPTIMIZED; ap->pre_handler = aggr_pre_handler; /* We don't care the kprobe which has gone. */ if (p->post_handler && !kprobe_gone(p)) ap->post_handler = aggr_post_handler;
INIT_LIST_HEAD(&ap->list); INIT_HLIST_NODE(&ap->hlist);
list_add_rcu(&p->list, &ap->list); hlist_replace_rcu(&p->hlist, &ap->hlist);}
/* * This registers the second or subsequent kprobe at the same address. */static int register_aggr_kprobe(struct kprobe *orig_p, struct kprobe *p){ int ret = 0; struct kprobe *ap = orig_p;
scoped_guard(cpus_read_lock) { /* For preparing optimization, jump_label_text_reserved() is called */ guard(jump_label_lock)(); guard(mutex)(&text_mutex);
if (!kprobe_aggrprobe(orig_p)) { /* If 'orig_p' is not an 'aggr_kprobe', create new one. */ ap = alloc_aggr_kprobe(orig_p); if (!ap) return -ENOMEM; init_aggr_kprobe(ap, orig_p); } else if (kprobe_unused(ap)) { /* This probe is going to die. Rescue it */ ret = reuse_unused_kprobe(ap); if (ret) 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 the 'ap'. It will be used next time, or * freed by unregister_kprobe(). */ return ret;
/* Prepare optimized instructions if possible. */ prepare_optimized_kprobe(ap);
/* * 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 the insn slot of 'p' to 'ap'. */ copy_kprobe(ap, p); ret = add_new_kprobe(ap, p); }
if (ret == 0 && kprobe_disabled(ap) && !kprobe_disabled(p)) { ap->flags &= ~KPROBE_FLAG_DISABLED; if (!kprobes_all_disarmed) { /* Arm the breakpoint again. */ ret = arm_kprobe(ap); if (ret) { ap->flags |= KPROBE_FLAG_DISABLED; list_del_rcu(&p->list); synchronize_rcu(); } } } return ret;}
bool __weak arch_within_kprobe_blacklist(unsigned long addr){ /* The '__kprobes' functions and entry code must not be probed. */ return addr >= (unsigned long)__kprobes_text_start && addr < (unsigned long)__kprobes_text_end;}
static bool __within_kprobe_blacklist(unsigned long addr){ struct kprobe_blacklist_entry *ent;
if (arch_within_kprobe_blacklist(addr)) return true; /* * If 'kprobe_blacklist' is defined, check the address and * reject any probe registration in the prohibited area. */ list_for_each_entry(ent, &kprobe_blacklist, list) { if (addr >= ent->start_addr && addr < ent->end_addr) return true; } return false;}
bool within_kprobe_blacklist(unsigned long addr){ char symname[KSYM_NAME_LEN], *p;
if (__within_kprobe_blacklist(addr)) return true;
/* Check if the address is on a suffixed-symbol */ if (!lookup_symbol_name(addr, symname)) { p = strchr(symname, '.'); if (!p) return false; *p = '\0'; addr = (unsigned long)kprobe_lookup_name(symname, 0); if (addr) return __within_kprobe_blacklist(addr); } return false;}
/* * arch_adjust_kprobe_addr - adjust the address * @addr: symbol base address * @offset: offset within the symbol * @on_func_entry: was this @addr+@offset on the function entry * * Typically returns @addr + @offset, except for special cases where the * function might be prefixed by a CFI landing pad, in that case any offset * inside the landing pad is mapped to the first 'real' instruction of the * symbol. * * Specifically, for things like IBT/BTI, skip the resp. ENDBR/BTI.C * instruction at +0. */kprobe_opcode_t *__weak arch_adjust_kprobe_addr(unsigned long addr, unsigned long offset, bool *on_func_entry){ *on_func_entry = !offset; return (kprobe_opcode_t *)(addr + offset);}
/* * If 'symbol_name' is specified, look it up and add the 'offset' * to it. This way, we can specify a relative address to a symbol. * This returns encoded errors if it fails to look up symbol or invalid * combination of parameters. */static kprobe_opcode_t *_kprobe_addr(kprobe_opcode_t *addr, const char *symbol_name, unsigned long offset, bool *on_func_entry){ if ((symbol_name && addr) || (!symbol_name && !addr)) return ERR_PTR(-EINVAL);
if (symbol_name) { /* * Input: @sym + @offset * Output: @addr + @offset * * NOTE: kprobe_lookup_name() does *NOT* fold the offset * argument into it's output! */ addr = kprobe_lookup_name(symbol_name, offset); if (!addr) return ERR_PTR(-ENOENT); }
/* * So here we have @addr + @offset, displace it into a new * @addr' + @offset' where @addr' is the symbol start address. */ addr = (void *)addr + offset; if (!kallsyms_lookup_size_offset((unsigned long)addr, NULL, &offset)) return ERR_PTR(-ENOENT); addr = (void *)addr - offset;
/* * Then ask the architecture to re-combine them, taking care of * magical function entry details while telling us if this was indeed * at the start of the function. */ addr = arch_adjust_kprobe_addr((unsigned long)addr, offset, on_func_entry); if (!addr) return ERR_PTR(-EINVAL);
return addr;}
static kprobe_opcode_t *kprobe_addr(struct kprobe *p){ bool on_func_entry;
return _kprobe_addr(p->addr, p->symbol_name, p->offset, &on_func_entry);}
/* * Check the 'p' is valid and return the aggregator kprobe * at the same address. */static struct kprobe *__get_valid_kprobe(struct kprobe *p){ struct kprobe *ap, *list_p;
lockdep_assert_held(&kprobe_mutex);
ap = get_kprobe(p->addr); if (unlikely(!ap)) return NULL;
if (p == ap) return ap;
list_for_each_entry(list_p, &ap->list, list) if (list_p == p) /* kprobe p is a valid probe */ return ap;
return NULL;}
/* * Warn and return error if the kprobe is being re-registered since * there must be a software bug. */static inline int warn_kprobe_rereg(struct kprobe *p){ guard(mutex)(&kprobe_mutex);
if (WARN_ON_ONCE(__get_valid_kprobe(p))) return -EINVAL;
return 0;}
static int check_ftrace_location(struct kprobe *p){ unsigned long addr = (unsigned long)p->addr;
if (ftrace_location(addr) == addr) {#ifdef CONFIG_KPROBES_ON_FTRACE p->flags |= KPROBE_FLAG_FTRACE;#else return -EINVAL;#endif } return 0;}
static bool is_cfi_preamble_symbol(unsigned long addr){ char symbuf[KSYM_NAME_LEN];
if (lookup_symbol_name(addr, symbuf)) return false;
return str_has_prefix(symbuf, "__cfi_") || str_has_prefix(symbuf, "__pfx_");}
static int check_kprobe_address_safe(struct kprobe *p, struct module **probed_mod){ int ret;
ret = check_ftrace_location(p); if (ret) return ret;
guard(jump_label_lock)();
/* Ensure the address is in a text area, and find a module if exists. */ *probed_mod = NULL; if (!core_kernel_text((unsigned long) p->addr)) { guard(rcu)(); *probed_mod = __module_text_address((unsigned long) p->addr); if (!(*probed_mod)) return -EINVAL;
/* * We must hold a refcount of the probed module while updating * its code to prohibit unexpected unloading. */ if (unlikely(!try_module_get(*probed_mod))) return -ENOENT; } /* Ensure it is not in reserved area. */ if (in_gate_area_no_mm((unsigned long) p->addr) || within_kprobe_blacklist((unsigned long) p->addr) || jump_label_text_reserved(p->addr, p->addr) || static_call_text_reserved(p->addr, p->addr) || find_bug((unsigned long)p->addr) || is_cfi_preamble_symbol((unsigned long)p->addr)) { module_put(*probed_mod); return -EINVAL; }
/* Get module refcount and reject __init functions for loaded modules. */ if (IS_ENABLED(CONFIG_MODULES) && *probed_mod) { /* * If the module freed '.init.text', we couldn't insert * kprobes in there. */ if (within_module_init((unsigned long)p->addr, *probed_mod) && !module_is_coming(*probed_mod)) { module_put(*probed_mod); return -ENOENT; } }
return 0;}
static int __register_kprobe(struct kprobe *p){ int ret; struct kprobe *old_p;
guard(mutex)(&kprobe_mutex);
old_p = get_kprobe(p->addr); if (old_p) /* Since this may unoptimize 'old_p', locking 'text_mutex'. */ return register_aggr_kprobe(old_p, p);
scoped_guard(cpus_read_lock) { /* Prevent text modification */ guard(mutex)(&text_mutex); ret = prepare_kprobe(p); if (ret) return ret; }
INIT_HLIST_NODE(&p->hlist); hlist_add_head_rcu(&p->hlist, &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
if (!kprobes_all_disarmed && !kprobe_disabled(p)) { ret = arm_kprobe(p); if (ret) { hlist_del_rcu(&p->hlist); synchronize_rcu(); } }
/* Try to optimize kprobe */ try_to_optimize_kprobe(p); return 0;}
int register_kprobe(struct kprobe *p){ int ret; struct module *probed_mod; kprobe_opcode_t *addr; bool on_func_entry;
/* Canonicalize probe address from symbol */ addr = _kprobe_addr(p->addr, p->symbol_name, p->offset, &on_func_entry); if (IS_ERR(addr)) return PTR_ERR(addr); p->addr = addr;
ret = warn_kprobe_rereg(p); if (ret) return ret;
/* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */ p->flags &= KPROBE_FLAG_DISABLED; if (on_func_entry) p->flags |= KPROBE_FLAG_ON_FUNC_ENTRY; p->nmissed = 0; INIT_LIST_HEAD(&p->list);
ret = check_kprobe_address_safe(p, &probed_mod); if (ret) return ret;
ret = __register_kprobe(p);
if (probed_mod) module_put(probed_mod);
return ret;}EXPORT_SYMBOL_GPL(register_kprobe);
/* Check if all probes on the 'ap' are disabled. */static bool aggr_kprobe_disabled(struct kprobe *ap){ struct kprobe *kp;
lockdep_assert_held(&kprobe_mutex);
list_for_each_entry(kp, &ap->list, list) if (!kprobe_disabled(kp)) /* * Since there is an active probe on the list, * we can't disable this 'ap'. */ return false;
return true;}
static struct kprobe *__disable_kprobe(struct kprobe *p){ struct kprobe *orig_p; int ret;
lockdep_assert_held(&kprobe_mutex);
/* Get an original kprobe for return */ orig_p = __get_valid_kprobe(p); if (unlikely(orig_p == NULL)) return ERR_PTR(-EINVAL);
if (kprobe_disabled(p)) return orig_p;
/* Disable probe if it is a child probe */ if (p != orig_p) p->flags |= KPROBE_FLAG_DISABLED;
/* Try to disarm and disable this/parent probe */ if (p == orig_p || aggr_kprobe_disabled(orig_p)) { /* * Don't be lazy here. Even if 'kprobes_all_disarmed' * is false, 'orig_p' might not have been armed yet. * Note arm_all_kprobes() __tries__ to arm all kprobes * on the best effort basis. */ if (!kprobes_all_disarmed && !kprobe_disabled(orig_p)) { ret = disarm_kprobe(orig_p, true); if (ret) { p->flags &= ~KPROBE_FLAG_DISABLED; return ERR_PTR(ret); } } orig_p->flags |= KPROBE_FLAG_DISABLED; }
return orig_p;}
/* * Unregister a kprobe without a scheduler synchronization. */static int __unregister_kprobe_top(struct kprobe *p){ struct kprobe *ap, *list_p;
/* Disable kprobe. This will disarm it if needed. */ ap = __disable_kprobe(p); if (IS_ERR(ap)) return PTR_ERR(ap);
WARN_ON(ap != p && !kprobe_aggrprobe(ap));
/* * If the probe is an independent(and non-optimized) kprobe * (not an aggrprobe), the last kprobe on the aggrprobe, or * kprobe is already disarmed, just remove from the hash list. */ if (ap == p || (list_is_singular(&ap->list) && kprobe_disarmed(ap))) { /* * !disarmed could be happen if the probe is under delayed * unoptimizing. */ hlist_del_rcu(&ap->hlist); return 0; }
/* If disabling probe has special handlers, update aggrprobe */ if (p->post_handler && !kprobe_gone(p)) { list_for_each_entry(list_p, &ap->list, list) { if ((list_p != p) && (list_p->post_handler)) break; } /* No other probe has post_handler */ if (list_entry_is_head(list_p, &ap->list, list)) { /* * For the kprobe-on-ftrace case, we keep the * post_handler setting to identify this aggrprobe * armed with kprobe_ipmodify_ops. */ if (!kprobe_ftrace(ap)) ap->post_handler = NULL; } }
/* * Remove from the aggrprobe: this path will do nothing in * __unregister_kprobe_bottom(). */ list_del_rcu(&p->list); if (!kprobe_disabled(ap) && !kprobes_all_disarmed) /* * Try to optimize this probe again, because post * handler may have been changed. */ optimize_kprobe(ap); return 0;
}
static void __unregister_kprobe_bottom(struct kprobe *p){ struct kprobe *ap;
if (list_empty(&p->list)) /* This is an independent kprobe */ arch_remove_kprobe(p); else if (list_is_singular(&p->list)) { /* This is the last child of an aggrprobe */ ap = list_entry(p->list.next, struct kprobe, list); list_del(&p->list); free_aggr_kprobe(ap); } /* Otherwise, do nothing. */}
int 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; } } return ret;}EXPORT_SYMBOL_GPL(register_kprobes);
void unregister_kprobe(struct kprobe *p){ unregister_kprobes(&p, 1);}EXPORT_SYMBOL_GPL(unregister_kprobe);
void unregister_kprobes(struct kprobe **kps, int num){ int i;
if (num <= 0) return; scoped_guard(mutex, &kprobe_mutex) { for (i = 0; i < num; i++) if (__unregister_kprobe_top(kps[i]) < 0) kps[i]->addr = NULL; } synchronize_rcu(); for (i = 0; i < num; i++) if (kps[i]->addr) __unregister_kprobe_bottom(kps[i]);}EXPORT_SYMBOL_GPL(unregister_kprobes);
int __weak kprobe_exceptions_notify(struct notifier_block *self, unsigned long val, void *data){ return NOTIFY_DONE;}NOKPROBE_SYMBOL(kprobe_exceptions_notify);
static struct notifier_block kprobe_exceptions_nb = { .notifier_call = kprobe_exceptions_notify, .priority = 0x7fffffff /* we need to be notified first */};
#ifdef CONFIG_KRETPROBES
#if !defined(CONFIG_KRETPROBE_ON_RETHOOK)
/* callbacks for objpool of kretprobe instances */static int kretprobe_init_inst(void *nod, void *context){ struct kretprobe_instance *ri = nod;
ri->rph = context; return 0;}static int kretprobe_fini_pool(struct objpool_head *head, void *context){ kfree(context); return 0;}
static void free_rp_inst_rcu(struct rcu_head *head){ struct kretprobe_instance *ri = container_of(head, struct kretprobe_instance, rcu); struct kretprobe_holder *rph = ri->rph;
objpool_drop(ri, &rph->pool);}NOKPROBE_SYMBOL(free_rp_inst_rcu);
static void recycle_rp_inst(struct kretprobe_instance *ri){ struct kretprobe *rp = get_kretprobe(ri);
if (likely(rp)) objpool_push(ri, &rp->rph->pool); else call_rcu(&ri->rcu, free_rp_inst_rcu);}NOKPROBE_SYMBOL(recycle_rp_inst);
/* * This function is called from delayed_put_task_struct() when a task is * dead and cleaned up to recycle any kretprobe instances associated with * this task. These left over instances represent probed functions that * have been called but will never return. */void kprobe_flush_task(struct task_struct *tk){ struct kretprobe_instance *ri; struct llist_node *node;
/* Early boot, not yet initialized. */ if (unlikely(!kprobes_initialized)) return;
kprobe_busy_begin();
node = __llist_del_all(&tk->kretprobe_instances); while (node) { ri = container_of(node, struct kretprobe_instance, llist); node = node->next;
recycle_rp_inst(ri); }
kprobe_busy_end();}NOKPROBE_SYMBOL(kprobe_flush_task);
static inline void free_rp_inst(struct kretprobe *rp){ struct kretprobe_holder *rph = rp->rph;
if (!rph) return; rp->rph = NULL; objpool_fini(&rph->pool);}
/* This assumes the 'tsk' is the current task or the is not running. */static kprobe_opcode_t *__kretprobe_find_ret_addr(struct task_struct *tsk, struct llist_node **cur){ struct kretprobe_instance *ri = NULL; struct llist_node *node = *cur;
if (!node) node = tsk->kretprobe_instances.first; else node = node->next;
while (node) { ri = container_of(node, struct kretprobe_instance, llist); if (ri->ret_addr != kretprobe_trampoline_addr()) { *cur = node; return ri->ret_addr; } node = node->next; } return NULL;}NOKPROBE_SYMBOL(__kretprobe_find_ret_addr);
/** * kretprobe_find_ret_addr -- Find correct return address modified by kretprobe * @tsk: Target task * @fp: A frame pointer * @cur: a storage of the loop cursor llist_node pointer for next call * * Find the correct return address modified by a kretprobe on @tsk in unsigned * long type. If it finds the return address, this returns that address value, * or this returns 0. * The @tsk must be 'current' or a task which is not running. @fp is a hint * to get the currect return address - which is compared with the * kretprobe_instance::fp field. The @cur is a loop cursor for searching the * kretprobe return addresses on the @tsk. The '*@cur' should be NULL at the * first call, but '@cur' itself must NOT NULL. */unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp, struct llist_node **cur){ struct kretprobe_instance *ri; kprobe_opcode_t *ret;
if (WARN_ON_ONCE(!cur)) return 0;
do { ret = __kretprobe_find_ret_addr(tsk, cur); if (!ret) break; ri = container_of(*cur, struct kretprobe_instance, llist); } while (ri->fp != fp);
return (unsigned long)ret;}NOKPROBE_SYMBOL(kretprobe_find_ret_addr);
void __weak arch_kretprobe_fixup_return(struct pt_regs *regs, kprobe_opcode_t *correct_ret_addr){ /* * Do nothing by default. Please fill this to update the fake return * address on the stack with the correct one on each arch if possible. */}
unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs, void *frame_pointer){ struct kretprobe_instance *ri = NULL; struct llist_node *first, *node = NULL; kprobe_opcode_t *correct_ret_addr; struct kretprobe *rp;
/* Find correct address and all nodes for this frame. */ correct_ret_addr = __kretprobe_find_ret_addr(current, &node); if (!correct_ret_addr) { pr_err("kretprobe: Return address not found, not execute handler. Maybe there is a bug in the kernel.\n"); BUG_ON(1); }
/* * Set the return address as the instruction pointer, because if the * user handler calls stack_trace_save_regs() with this 'regs', * the stack trace will start from the instruction pointer. */ instruction_pointer_set(regs, (unsigned long)correct_ret_addr);
/* Run the user handler of the nodes. */ first = current->kretprobe_instances.first; while (first) { ri = container_of(first, struct kretprobe_instance, llist);
if (WARN_ON_ONCE(ri->fp != frame_pointer)) break;
rp = get_kretprobe(ri); if (rp && rp->handler) { struct kprobe *prev = kprobe_running();
__this_cpu_write(current_kprobe, &rp->kp); ri->ret_addr = correct_ret_addr; rp->handler(ri, regs); __this_cpu_write(current_kprobe, prev); } if (first == node) break;
first = first->next; }
arch_kretprobe_fixup_return(regs, correct_ret_addr);
/* Unlink all nodes for this frame. */ first = current->kretprobe_instances.first; current->kretprobe_instances.first = node->next; node->next = NULL;
/* Recycle free instances. */ while (first) { ri = container_of(first, struct kretprobe_instance, llist); first = first->next;
recycle_rp_inst(ri); }
return (unsigned long)correct_ret_addr;}NOKPROBE_SYMBOL(__kretprobe_trampoline_handler)
/* * This kprobe pre_handler is registered with every kretprobe. When probe * hits it will set up the return probe. */static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs){ struct kretprobe *rp = container_of(p, struct kretprobe, kp); struct kretprobe_holder *rph = rp->rph; struct kretprobe_instance *ri;
ri = objpool_pop(&rph->pool); if (!ri) { rp->nmissed++; return 0; }
if (rp->entry_handler && rp->entry_handler(ri, regs)) { objpool_push(ri, &rph->pool); return 0; }
arch_prepare_kretprobe(ri, regs);
__llist_add(&ri->llist, ¤t->kretprobe_instances);
return 0;}NOKPROBE_SYMBOL(pre_handler_kretprobe);#else /* CONFIG_KRETPROBE_ON_RETHOOK *//* * This kprobe pre_handler is registered with every kretprobe. When probe * hits it will set up the return probe. */static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs){ struct kretprobe *rp = container_of(p, struct kretprobe, kp); struct kretprobe_instance *ri; struct rethook_node *rhn;
rhn = rethook_try_get(rp->rh); if (!rhn) { rp->nmissed++; return 0; }
ri = container_of(rhn, struct kretprobe_instance, node);
if (rp->entry_handler && rp->entry_handler(ri, regs)) rethook_recycle(rhn); else rethook_hook(rhn, regs, kprobe_ftrace(p));
return 0;}NOKPROBE_SYMBOL(pre_handler_kretprobe);
static void kretprobe_rethook_handler(struct rethook_node *rh, void *data, unsigned long ret_addr, struct pt_regs *regs){ struct kretprobe *rp = (struct kretprobe *)data; struct kretprobe_instance *ri; struct kprobe_ctlblk *kcb;
/* The data must NOT be null. This means rethook data structure is broken. */ if (WARN_ON_ONCE(!data) || !rp->handler) return;
__this_cpu_write(current_kprobe, &rp->kp); kcb = get_kprobe_ctlblk(); kcb->kprobe_status = KPROBE_HIT_ACTIVE;
ri = container_of(rh, struct kretprobe_instance, node); rp->handler(ri, regs);
__this_cpu_write(current_kprobe, NULL);}NOKPROBE_SYMBOL(kretprobe_rethook_handler);
#endif /* !CONFIG_KRETPROBE_ON_RETHOOK */
/** * kprobe_on_func_entry() -- check whether given address is function entry * @addr: Target address * @sym: Target symbol name * @offset: The offset from the symbol or the address * * This checks whether the given @addr+@offset or @sym+@offset is on the * function entry address or not. * This returns 0 if it is the function entry, or -EINVAL if it is not. * And also it returns -ENOENT if it fails the symbol or address lookup. * Caller must pass @addr or @sym (either one must be NULL), or this * returns -EINVAL. */int kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset){ bool on_func_entry; kprobe_opcode_t *kp_addr = _kprobe_addr(addr, sym, offset, &on_func_entry);
if (IS_ERR(kp_addr)) return PTR_ERR(kp_addr);
if (!on_func_entry) return -EINVAL;
return 0;}
int register_kretprobe(struct kretprobe *rp){ int ret; int i; void *addr;
ret = kprobe_on_func_entry(rp->kp.addr, rp->kp.symbol_name, rp->kp.offset); if (ret) return ret;
/* If only 'rp->kp.addr' is specified, check reregistering kprobes */ if (rp->kp.addr && warn_kprobe_rereg(&rp->kp)) return -EINVAL;
if (kretprobe_blacklist_size) { addr = kprobe_addr(&rp->kp); if (IS_ERR(addr)) return PTR_ERR(addr);
for (i = 0; kretprobe_blacklist[i].name != NULL; i++) { if (kretprobe_blacklist[i].addr == addr) return -EINVAL; } }
if (rp->data_size > KRETPROBE_MAX_DATA_SIZE) return -E2BIG;
rp->kp.pre_handler = pre_handler_kretprobe; rp->kp.post_handler = NULL;
/* Pre-allocate memory for max kretprobe instances */ if (rp->maxactive <= 0) rp->maxactive = max_t(unsigned int, 10, 2*num_possible_cpus());
#ifdef CONFIG_KRETPROBE_ON_RETHOOK rp->rh = rethook_alloc((void *)rp, kretprobe_rethook_handler, sizeof(struct kretprobe_instance) + rp->data_size, rp->maxactive); if (IS_ERR(rp->rh)) return PTR_ERR(rp->rh);
rp->nmissed = 0; /* Establish function entry probe point */ ret = register_kprobe(&rp->kp); if (ret != 0) { rethook_free(rp->rh); rp->rh = NULL; }#else /* !CONFIG_KRETPROBE_ON_RETHOOK */ rp->rph = kzalloc_obj(struct kretprobe_holder); if (!rp->rph) return -ENOMEM;
if (objpool_init(&rp->rph->pool, rp->maxactive, rp->data_size + sizeof(struct kretprobe_instance), GFP_KERNEL, rp->rph, kretprobe_init_inst, kretprobe_fini_pool)) { kfree(rp->rph); rp->rph = NULL; return -ENOMEM; } rcu_assign_pointer(rp->rph->rp, rp); rp->nmissed = 0; /* Establish function entry probe point */ ret = register_kprobe(&rp->kp); if (ret != 0) free_rp_inst(rp);#endif return ret;}EXPORT_SYMBOL_GPL(register_kretprobe);
int 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 unregister_kretprobe(struct kretprobe *rp){ unregister_kretprobes(&rp, 1);}EXPORT_SYMBOL_GPL(unregister_kretprobe);
void unregister_kretprobes(struct kretprobe **rps, int num){ int i;
if (num <= 0) return; for (i = 0; i < num; i++) { guard(mutex)(&kprobe_mutex);
if (__unregister_kprobe_top(&rps[i]->kp) < 0) rps[i]->kp.addr = NULL;#ifdef CONFIG_KRETPROBE_ON_RETHOOK rethook_free(rps[i]->rh);#else rcu_assign_pointer(rps[i]->rph->rp, NULL);#endif }
synchronize_rcu(); for (i = 0; i < num; i++) { if (rps[i]->kp.addr) { __unregister_kprobe_bottom(&rps[i]->kp);#ifndef CONFIG_KRETPROBE_ON_RETHOOK free_rp_inst(rps[i]);#endif } }}EXPORT_SYMBOL_GPL(unregister_kretprobes);
#else /* CONFIG_KRETPROBES */int register_kretprobe(struct kretprobe *rp){ return -EOPNOTSUPP;}EXPORT_SYMBOL_GPL(register_kretprobe);
int register_kretprobes(struct kretprobe **rps, int num){ return -EOPNOTSUPP;}EXPORT_SYMBOL_GPL(register_kretprobes);
void unregister_kretprobe(struct kretprobe *rp){}EXPORT_SYMBOL_GPL(unregister_kretprobe);
void unregister_kretprobes(struct kretprobe **rps, int num){}EXPORT_SYMBOL_GPL(unregister_kretprobes);
static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs){ return 0;}NOKPROBE_SYMBOL(pre_handler_kretprobe);
#endif /* CONFIG_KRETPROBES */
/* Set the kprobe gone and remove its instruction buffer. */static void kill_kprobe(struct kprobe *p){ struct kprobe *kp;
lockdep_assert_held(&kprobe_mutex);
/* * The module is going away. We should disarm the kprobe which * is using ftrace, because ftrace framework is still available at * 'MODULE_STATE_GOING' notification. */ if (kprobe_ftrace(p) && !kprobe_disabled(p) && !kprobes_all_disarmed) disarm_kprobe_ftrace(p);
p->flags |= KPROBE_FLAG_GONE; if (kprobe_aggrprobe(p)) { /* * If this is an aggr_kprobe, we have to list all the * chained probes and mark them GONE. */ list_for_each_entry(kp, &p->list, list) kp->flags |= KPROBE_FLAG_GONE; p->post_handler = NULL; kill_optimized_kprobe(p); } /* * 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);}
/* Disable one kprobe */int disable_kprobe(struct kprobe *kp){ struct kprobe *p;
guard(mutex)(&kprobe_mutex);
/* Disable this kprobe */ p = __disable_kprobe(kp);
return IS_ERR(p) ? PTR_ERR(p) : 0;}EXPORT_SYMBOL_GPL(disable_kprobe);
/* Enable one kprobe */int enable_kprobe(struct kprobe *kp){ int ret = 0; struct kprobe *p;
guard(mutex)(&kprobe_mutex);
/* Check whether specified probe is valid. */ p = __get_valid_kprobe(kp); if (unlikely(p == NULL)) return -EINVAL;
if (kprobe_gone(kp)) /* This kprobe has gone, we couldn't enable it. */ return -EINVAL;
if (p != kp) kp->flags &= ~KPROBE_FLAG_DISABLED;
if (!kprobes_all_disarmed && kprobe_disabled(p)) { p->flags &= ~KPROBE_FLAG_DISABLED; ret = arm_kprobe(p); if (ret) { p->flags |= KPROBE_FLAG_DISABLED; if (p != kp) kp->flags |= KPROBE_FLAG_DISABLED; } } return ret;}EXPORT_SYMBOL_GPL(enable_kprobe);
/* Caller must NOT call this in usual path. This is only for critical case */void dump_kprobe(struct kprobe *kp){ pr_err("Dump kprobe:\n.symbol_name = %s, .offset = %x, .addr = %pS\n", kp->symbol_name, kp->offset, kp->addr);}NOKPROBE_SYMBOL(dump_kprobe);
int kprobe_add_ksym_blacklist(unsigned long entry){ struct kprobe_blacklist_entry *ent; unsigned long offset = 0, size = 0;
if (!kernel_text_address(entry) || !kallsyms_lookup_size_offset(entry, &size, &offset)) return -EINVAL;
ent = kmalloc_obj(*ent); if (!ent) return -ENOMEM; ent->start_addr = entry; ent->end_addr = entry + size; INIT_LIST_HEAD(&ent->list); list_add_tail(&ent->list, &kprobe_blacklist);
return (int)size;}
/* Add all symbols in given area into kprobe blacklist */int kprobe_add_area_blacklist(unsigned long start, unsigned long end){ unsigned long entry; int ret = 0;
for (entry = start; entry < end; entry += ret) { ret = kprobe_add_ksym_blacklist(entry); if (ret < 0) return ret; if (ret == 0) /* In case of alias symbol */ ret = 1; } return 0;}
int __weak arch_kprobe_get_kallsym(unsigned int *symnum, unsigned long *value, char *type, char *sym){ return -ERANGE;}
int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, char *type, char *sym){#ifdef __ARCH_WANT_KPROBES_INSN_SLOT if (!kprobe_cache_get_kallsym(&kprobe_insn_slots, &symnum, value, type, sym)) return 0;#ifdef CONFIG_OPTPROBES if (!kprobe_cache_get_kallsym(&kprobe_optinsn_slots, &symnum, value, type, sym)) return 0;#endif#endif if (!arch_kprobe_get_kallsym(&symnum, value, type, sym)) return 0; return -ERANGE;}
int __init __weak arch_populate_kprobe_blacklist(void){ return 0;}
/* * 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. */static int __init populate_kprobe_blacklist(unsigned long *start, unsigned long *end){ unsigned long entry; unsigned long *iter; int ret;
for (iter = start; iter < end; iter++) { entry = (unsigned long)dereference_symbol_descriptor((void *)*iter); ret = kprobe_add_ksym_blacklist(entry); if (ret == -EINVAL) continue; if (ret < 0) return ret; }
/* Symbols in '__kprobes_text' are blacklisted */ ret = kprobe_add_area_blacklist((unsigned long)__kprobes_text_start, (unsigned long)__kprobes_text_end); if (ret) return ret;
/* Symbols in 'noinstr' section are blacklisted */ ret = kprobe_add_area_blacklist((unsigned long)__noinstr_text_start, (unsigned long)__noinstr_text_end);
return ret ? : arch_populate_kprobe_blacklist();}
#ifdef CONFIG_MODULES/* Remove all symbols in given area from kprobe blacklist */static void kprobe_remove_area_blacklist(unsigned long start, unsigned long end){ struct kprobe_blacklist_entry *ent, *n;
list_for_each_entry_safe(ent, n, &kprobe_blacklist, list) { if (ent->start_addr < start || ent->start_addr >= end) continue; list_del(&ent->list); kfree(ent); }}
static void kprobe_remove_ksym_blacklist(unsigned long entry){ kprobe_remove_area_blacklist(entry, entry + 1);}
static void add_module_kprobe_blacklist(struct module *mod){ unsigned long start, end; int i;
if (mod->kprobe_blacklist) { for (i = 0; i < mod->num_kprobe_blacklist; i++) kprobe_add_ksym_blacklist(mod->kprobe_blacklist[i]); }
start = (unsigned long)mod->kprobes_text_start; if (start) { end = start + mod->kprobes_text_size; kprobe_add_area_blacklist(start, end); }
start = (unsigned long)mod->noinstr_text_start; if (start) { end = start + mod->noinstr_text_size; kprobe_add_area_blacklist(start, end); }}
static void remove_module_kprobe_blacklist(struct module *mod){ unsigned long start, end; int i;
if (mod->kprobe_blacklist) { for (i = 0; i < mod->num_kprobe_blacklist; i++) kprobe_remove_ksym_blacklist(mod->kprobe_blacklist[i]); }
start = (unsigned long)mod->kprobes_text_start; if (start) { end = start + mod->kprobes_text_size; kprobe_remove_area_blacklist(start, end); }
start = (unsigned long)mod->noinstr_text_start; if (start) { end = start + mod->noinstr_text_size; kprobe_remove_area_blacklist(start, end); }}
/* Module notifier call back, checking kprobes on the module */static int kprobes_module_callback(struct notifier_block *nb, unsigned long val, void *data){ struct module *mod = data; struct hlist_head *head; struct kprobe *p; unsigned int i; int checkcore = (val == MODULE_STATE_GOING);
guard(mutex)(&kprobe_mutex);
if (val == MODULE_STATE_COMING) add_module_kprobe_blacklist(mod);
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. */ for (i = 0; i < KPROBE_TABLE_SIZE; i++) { head = &kprobe_table[i]; hlist_for_each_entry(p, 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. * * Note, this will also move any optimized probes * that are pending to be removed from their * corresponding lists to the 'freeing_list' and * will not be touched by the delayed * kprobe_optimizer() work handler. */ kill_kprobe(p); } } if (val == MODULE_STATE_GOING) remove_module_kprobe_blacklist(mod); return NOTIFY_DONE;}
static struct notifier_block kprobe_module_nb = { .notifier_call = kprobes_module_callback, .priority = 0};
static int kprobe_register_module_notifier(void){ return register_module_notifier(&kprobe_module_nb);}#elsestatic int kprobe_register_module_notifier(void){ return 0;}#endif /* CONFIG_MODULES */
void kprobe_free_init_mem(void){ void *start = (void *)(&__init_begin); void *end = (void *)(&__init_end); struct hlist_head *head; struct kprobe *p; int i;
guard(mutex)(&kprobe_mutex);
/* Kill all kprobes on initmem because the target code has been freed. */ for (i = 0; i < KPROBE_TABLE_SIZE; i++) { head = &kprobe_table[i]; hlist_for_each_entry(p, head, hlist) { if (start <= (void *)p->addr && (void *)p->addr < end) kill_kprobe(p); } }}
static int __init init_kprobes(void){ int i, err;
/* 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]);
err = populate_kprobe_blacklist(__start_kprobe_blacklist, __stop_kprobe_blacklist); if (err) pr_err("Failed to populate blacklist (error %d), kprobes not restricted, be careful using them!\n", err);
if (kretprobe_blacklist_size) { /* lookup the function address from its name */ for (i = 0; kretprobe_blacklist[i].name != NULL; i++) { kretprobe_blacklist[i].addr = kprobe_lookup_name(kretprobe_blacklist[i].name, 0); if (!kretprobe_blacklist[i].addr) pr_err("Failed to lookup symbol '%s' for kretprobe blacklist. Maybe the target function is removed or renamed.\n", kretprobe_blacklist[i].name); } }
/* By default, kprobes are armed */ kprobes_all_disarmed = false;
/* Initialize the optimization infrastructure */ init_optprobe();
err = arch_init_kprobes(); if (!err) err = register_die_notifier(&kprobe_exceptions_nb); if (!err) err = kprobe_register_module_notifier();
kprobes_initialized = (err == 0); kprobe_sysctls_init(); return err;}early_initcall(init_kprobes);
#if defined(CONFIG_OPTPROBES)static int __init init_optprobes(void){ /* * Enable kprobe optimization - this kicks the optimizer which * depends on synchronize_rcu_tasks() and ksoftirqd, that is * not spawned in early initcall. So delay the optimization. */ optimize_all_kprobes();
return 0;}subsys_initcall(init_optprobes);#endif
#ifdef CONFIG_DEBUG_FSstatic void report_probe(struct seq_file *pi, struct kprobe *p, const char *sym, int offset, char *modname, struct kprobe *pp){ char *kprobe_type; void *addr = p->addr;
if (p->pre_handler == pre_handler_kretprobe) kprobe_type = "r"; else kprobe_type = "k";
if (!kallsyms_show_value(pi->file->f_cred)) addr = NULL;
if (sym) seq_printf(pi, "%px %s %s+0x%x %s ", addr, kprobe_type, sym, offset, (modname ? modname : " ")); else /* try to use %pS */ seq_printf(pi, "%px %s %pS ", addr, kprobe_type, p->addr);
if (!pp) pp = p; seq_printf(pi, "%s%s%s%s\n", (kprobe_gone(p) ? "[GONE]" : ""), ((kprobe_disabled(p) && !kprobe_gone(p)) ? "[DISABLED]" : ""), (kprobe_optimized(pp) ? "[OPTIMIZED]" : ""), (kprobe_ftrace(pp) ? "[FTRACE]" : ""));}
static void *kprobe_seq_start(struct seq_file *f, loff_t *pos){ return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL;}
static void *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos){ (*pos)++; if (*pos >= KPROBE_TABLE_SIZE) return NULL; return pos;}
static void kprobe_seq_stop(struct seq_file *f, void *v){ /* Nothing to do */}
static int show_kprobe_addr(struct seq_file *pi, void *v){ struct hlist_head *head; struct kprobe *p, *kp; const char *sym; unsigned int i = *(loff_t *) v; unsigned long offset = 0; char *modname, namebuf[KSYM_NAME_LEN];
head = &kprobe_table[i]; preempt_disable(); hlist_for_each_entry_rcu(p, head, hlist) { sym = kallsyms_lookup((unsigned long)p->addr, NULL, &offset, &modname, namebuf); if (kprobe_aggrprobe(p)) { list_for_each_entry_rcu(kp, &p->list, list) report_probe(pi, kp, sym, offset, modname, p); } else report_probe(pi, p, sym, offset, modname, NULL); } preempt_enable(); return 0;}
static const struct seq_operations kprobes_sops = { .start = kprobe_seq_start, .next = kprobe_seq_next, .stop = kprobe_seq_stop, .show = show_kprobe_addr};
DEFINE_SEQ_ATTRIBUTE(kprobes);
/* kprobes/blacklist -- shows which functions can not be probed */static void *kprobe_blacklist_seq_start(struct seq_file *m, loff_t *pos){ mutex_lock(&kprobe_mutex); return seq_list_start(&kprobe_blacklist, *pos);}
static void *kprobe_blacklist_seq_next(struct seq_file *m, void *v, loff_t *pos){ return seq_list_next(v, &kprobe_blacklist, pos);}
static int kprobe_blacklist_seq_show(struct seq_file *m, void *v){ struct kprobe_blacklist_entry *ent = list_entry(v, struct kprobe_blacklist_entry, list);
/* * If '/proc/kallsyms' is not showing kernel address, we won't * show them here either. */ if (!kallsyms_show_value(m->file->f_cred)) seq_printf(m, "0x%px-0x%px\t%ps\n", NULL, NULL, (void *)ent->start_addr); else seq_printf(m, "0x%px-0x%px\t%ps\n", (void *)ent->start_addr, (void *)ent->end_addr, (void *)ent->start_addr); return 0;}
static void kprobe_blacklist_seq_stop(struct seq_file *f, void *v){ mutex_unlock(&kprobe_mutex);}
static const struct seq_operations kprobe_blacklist_sops = { .start = kprobe_blacklist_seq_start, .next = kprobe_blacklist_seq_next, .stop = kprobe_blacklist_seq_stop, .show = kprobe_blacklist_seq_show,};DEFINE_SEQ_ATTRIBUTE(kprobe_blacklist);
static int arm_all_kprobes(void){ struct hlist_head *head; struct kprobe *p; unsigned int i, total = 0, errors = 0; int err, ret = 0;
guard(mutex)(&kprobe_mutex);
/* If kprobes are armed, just return */ if (!kprobes_all_disarmed) return 0;
/* * optimize_kprobe() called by arm_kprobe() checks * kprobes_all_disarmed, so set kprobes_all_disarmed before * arm_kprobe. */ kprobes_all_disarmed = false; /* Arming kprobes doesn't optimize kprobe itself */ for (i = 0; i < KPROBE_TABLE_SIZE; i++) { head = &kprobe_table[i]; /* Arm all kprobes on a best-effort basis */ hlist_for_each_entry(p, head, hlist) { if (!kprobe_disabled(p)) { err = arm_kprobe(p); if (err) { errors++; ret = err; } total++; } } }
if (errors) pr_warn("Kprobes globally enabled, but failed to enable %d out of %d probes. Please check which kprobes are kept disabled via debugfs.\n", errors, total); else pr_info("Kprobes globally enabled\n");
return ret;}
static int disarm_all_kprobes(void){ struct hlist_head *head; struct kprobe *p; unsigned int i, total = 0, errors = 0; int err, ret = 0;
guard(mutex)(&kprobe_mutex);
/* If kprobes are already disarmed, just return */ if (kprobes_all_disarmed) return 0;
kprobes_all_disarmed = true;
for (i = 0; i < KPROBE_TABLE_SIZE; i++) { head = &kprobe_table[i]; /* Disarm all kprobes on a best-effort basis */ hlist_for_each_entry(p, head, hlist) { if (!arch_trampoline_kprobe(p) && !kprobe_disabled(p)) { err = disarm_kprobe(p, false); if (err) { errors++; ret = err; } total++; } } }
if (errors) pr_warn("Kprobes globally disabled, but failed to disable %d out of %d probes. Please check which kprobes are kept enabled via debugfs.\n", errors, total); else pr_info("Kprobes globally disabled\n");
/* Wait for disarming all kprobes by optimizer */ wait_for_kprobe_optimizer_locked(); return ret;}
/* * 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 (!kprobes_all_disarmed) 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){ bool enable; int ret;
ret = kstrtobool_from_user(user_buf, count, &enable); if (ret) return ret;
ret = enable ? arm_all_kprobes() : disarm_all_kprobes(); if (ret) return ret;
return count;}
static const struct file_operations fops_kp = { .read = read_enabled_file_bool, .write = write_enabled_file_bool, .llseek = default_llseek,};
static int __init debugfs_kprobe_init(void){ struct dentry *dir;
dir = debugfs_create_dir("kprobes", NULL);
debugfs_create_file("list", 0400, dir, NULL, &kprobes_fops);
debugfs_create_file("enabled", 0600, dir, NULL, &fops_kp);
debugfs_create_file("blacklist", 0400, dir, NULL, &kprobe_blacklist_fops);
return 0;}
late_initcall(debugfs_kprobe_init);#endif /* CONFIG_DEBUG_FS */