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linux/kernel/kprobes.c
Jakub Kicinski a08d97a193 Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 
Daniel Borkmann says:

====================
pull-request: bpf-next 2022-10-03

We've added 143 non-merge commits during the last 27 day(s) which contain
a total of 151 files changed, 8321 insertions(+), 1402 deletions(-).

The main changes are:

1) Add kfuncs for PKCS#7 signature verification from BPF programs, from Roberto Sassu.

2) Add support for struct-based arguments for trampoline based BPF programs,
   from Yonghong Song.

3) Fix entry IP for kprobe-multi and trampoline probes under IBT enabled, from Jiri Olsa.

4) Batch of improvements to veristat selftest tool in particular to add CSV output,
   a comparison mode for CSV outputs and filtering, from Andrii Nakryiko.

5) Add preparatory changes needed for the BPF core for upcoming BPF HID support,
   from Benjamin Tissoires.

6) Support for direct writes to nf_conn's mark field from tc and XDP BPF program
   types, from Daniel Xu.

7) Initial batch of documentation improvements for BPF insn set spec, from Dave Thaler.

8) Add a new BPF_MAP_TYPE_USER_RINGBUF map which provides single-user-space-producer /
   single-kernel-consumer semantics for BPF ring buffer, from David Vernet.

9) Follow-up fixes to BPF allocator under RT to always use raw spinlock for the BPF
   hashtab's bucket lock, from Hou Tao.

10) Allow creating an iterator that loops through only the resources of one
    task/thread instead of all, from Kui-Feng Lee.

11) Add support for kptrs in the per-CPU arraymap, from Kumar Kartikeya Dwivedi.

12) Add a new kfunc helper for nf to set src/dst NAT IP/port in a newly allocated CT
    entry which is not yet inserted, from Lorenzo Bianconi.

13) Remove invalid recursion check for struct_ops for TCP congestion control BPF
    programs, from Martin KaFai Lau.

14) Fix W^X issue with BPF trampoline and BPF dispatcher, from Song Liu.

15) Fix percpu_counter leakage in BPF hashtab allocation error path, from Tetsuo Handa.

16) Various cleanups in BPF selftests to use preferred ASSERT_* macros, from Wang Yufen.

17) Add invocation for cgroup/connect{4,6} BPF programs for ICMP pings, from YiFei Zhu.

18) Lift blinding decision under bpf_jit_harden = 1 to bpf_capable(), from Yauheni Kaliuta.

19) Various libbpf fixes and cleanups including a libbpf NULL pointer deref, from Xin Liu.

* https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (143 commits)
  net: netfilter: move bpf_ct_set_nat_info kfunc in nf_nat_bpf.c
  Documentation: bpf: Add implementation notes documentations to table of contents
  bpf, docs: Delete misformatted table.
  selftests/xsk: Fix double free
  bpftool: Fix error message of strerror
  libbpf: Fix overrun in netlink attribute iteration
  selftests/bpf: Fix spelling mistake "unpriviledged" -> "unprivileged"
  samples/bpf: Fix typo in xdp_router_ipv4 sample
  bpftool: Remove unused struct event_ring_info
  bpftool: Remove unused struct btf_attach_point
  bpf, docs: Add TOC and fix formatting.
  bpf, docs: Add Clang note about BPF_ALU
  bpf, docs: Move Clang notes to a separate file
  bpf, docs: Linux byteswap note
  bpf, docs: Move legacy packet instructions to a separate file
  selftests/bpf: Check -EBUSY for the recurred bpf_setsockopt(TCP_CONGESTION)
  bpf: tcp: Stop bpf_setsockopt(TCP_CONGESTION) in init ops to recur itself
  bpf: Refactor bpf_setsockopt(TCP_CONGESTION) handling into another function
  bpf: Move the "cdg" tcp-cc check to the common sol_tcp_sockopt()
  bpf: Add __bpf_prog_{enter,exit}_struct_ops for struct_ops trampoline
  ...
====================

Link: https://lore.kernel.org/r/20221003194915.11847-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-10-03 13:02:49 -07:00

3029 lines
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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/moduleloader.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/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 <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[];
};
#define KPROBE_INSN_PAGE_SIZE(slots) \
(offsetof(struct kprobe_insn_page, slot_used) + \
(sizeof(char) * (slots)))
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 module_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 module_alloc(PAGE_SIZE);
}
static void free_insn_page(void *page)
{
module_memfree(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.
* We allocate an executable page if there's no room on existing ones.
*/
kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c)
{
struct kprobe_insn_page *kip;
kprobe_opcode_t *slot = NULL;
/* Since the slot array is not protected by rcu, we need a mutex */
mutex_lock(&c->mutex);
retry:
rcu_read_lock();
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++;
slot = kip->insns + (i * c->insn_size);
rcu_read_unlock();
goto out;
}
}
/* kip->nused is broken. Fix it. */
kip->nused = slots_per_page(c);
WARN_ON(1);
}
}
rcu_read_unlock();
/* If there are any garbage slots, collect it and try again. */
if (c->nr_garbage && collect_garbage_slots(c) == 0)
goto retry;
/* All out of space. Need to allocate a new page. */
kip = kmalloc(KPROBE_INSN_PAGE_SIZE(slots_per_page(c)), GFP_KERNEL);
if (!kip)
goto out;
kip->insns = c->alloc();
if (!kip->insns) {
kfree(kip);
goto out;
}
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);
slot = kip->insns;
/* 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);
out:
mutex_unlock(&c->mutex);
return slot;
}
/* 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) {
/*
* 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;
}
return false;
}
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;
}
void __free_insn_slot(struct kprobe_insn_cache *c,
kprobe_opcode_t *slot, int dirty)
{
struct kprobe_insn_page *kip;
long idx;
mutex_lock(&c->mutex);
rcu_read_lock();
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))
goto out;
}
/* Could not find this slot. */
WARN_ON(1);
kip = NULL;
out:
rcu_read_unlock();
/* 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);
}
}
mutex_unlock(&c->mutex);
}
/*
* 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_OPTPROBES
void __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
#endif
/* 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 */
static inline 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 kprobe_optimizer(struct work_struct *work);
static DECLARE_DELAYED_WORK(optimizing_work, kprobe_optimizer);
#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();
/* Unoptimization must be done anytime */
if (list_empty(&unoptimizing_list))
return;
arch_unoptimize_kprobes(&unoptimizing_list, &freeing_list);
/* Loop on 'freeing_list' for disarming */
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 */
if (kprobe_disabled(&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;
}
free_aggr_kprobe(&op->kp);
}
}
/* Start optimizer after OPTIMIZE_DELAY passed */
static void kick_kprobe_optimizer(void)
{
schedule_delayed_work(&optimizing_work, OPTIMIZE_DELAY);
}
/* Kprobe jump optimizer */
static void kprobe_optimizer(struct work_struct *work)
{
mutex_lock(&kprobe_mutex);
cpus_read_lock();
mutex_lock(&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();
mutex_unlock(&text_mutex);
cpus_read_unlock();
/* Step 5: Kick optimizer again if needed */
if (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list))
kick_kprobe_optimizer();
mutex_unlock(&kprobe_mutex);
}
/* Wait for completing optimization and unoptimization */
void wait_for_kprobe_optimizer(void)
{
mutex_lock(&kprobe_mutex);
while (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list)) {
mutex_unlock(&kprobe_mutex);
/* This will also make 'optimizing_work' execute immmediately */
flush_delayed_work(&optimizing_work);
/* 'optimizing_work' might not have been queued yet, relax */
cpu_relax();
mutex_lock(&kprobe_mutex);
}
mutex_unlock(&kprobe_mutex);
}
static 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)) {
/* Enqueue if it is unused */
list_add(&op->list, &freeing_list);
/*
* Remove unused probes from the hash list. After waiting
* for synchronization, this probe is reclaimed.
* (reclaiming is done by do_free_cleaned_kprobes().)
*/
hlist_del_rcu(&op->kp.hlist);
}
/* Don't touch the code, because it is already freed. */
arch_remove_optimized_kprobe(op);
}
static inline
void __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(sizeof(struct optimized_kprobe), GFP_KERNEL);
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. */
cpus_read_lock();
jump_label_lock();
mutex_lock(&text_mutex);
ap = alloc_aggr_kprobe(p);
if (!ap)
goto out;
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);
goto out;
}
init_aggr_kprobe(ap, p);
optimize_kprobe(ap); /* This just kicks optimizer thread. */
out:
mutex_unlock(&text_mutex);
jump_label_unlock();
cpus_read_unlock();
}
static void optimize_all_kprobes(void)
{
struct hlist_head *head;
struct kprobe *p;
unsigned int i;
mutex_lock(&kprobe_mutex);
/* If optimization is already allowed, just return. */
if (kprobes_allow_optimization)
goto out;
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");
out:
mutex_unlock(&kprobe_mutex);
}
#ifdef CONFIG_SYSCTL
static void unoptimize_all_kprobes(void)
{
struct hlist_head *head;
struct kprobe *p;
unsigned int i;
mutex_lock(&kprobe_mutex);
/* If optimization is already prohibited, just return. */
if (!kprobes_allow_optimization) {
mutex_unlock(&kprobe_mutex);
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();
mutex_unlock(&kprobe_mutex);
/* Wait for unoptimizing completion. */
wait_for_kprobe_optimizer();
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(struct ctl_table *table,
int write, void *buffer,
size_t *length, loff_t *ppos)
{
int ret;
mutex_lock(&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();
mutex_unlock(&kprobe_sysctl_mutex);
return ret;
}
static 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);
}
/*
* TODO: Since unoptimization and real disarming will be done by
* the worker thread, we can not check whether another probe are
* unoptimized because of this probe here. It should be re-optimized
* by the worker thread.
*/
}
#else /* !CONFIG_OPTPROBES */
#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() do {} while (0)
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(sizeof(struct kprobe), GFP_KERNEL);
}
#endif /* CONFIG_OPTPROBES */
#ifdef CONFIG_KPROBES_ON_FTRACE
static 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;
static int __arm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops,
int *cnt)
{
int ret = 0;
lockdep_assert_held(&kprobe_mutex);
ret = ftrace_set_filter_ip(ops, (unsigned long)p->addr, 0, 0);
if (WARN_ONCE(ret < 0, "Failed to arm kprobe-ftrace at %pS (error %d)\n", p->addr, ret))
return ret;
if (*cnt == 0) {
ret = register_ftrace_function(ops);
if (WARN(ret < 0, "Failed to register kprobe-ftrace (error %d)\n", ret))
goto err_ftrace;
}
(*cnt)++;
return ret;
err_ftrace:
/*
* 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;
}
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 = 0;
lockdep_assert_held(&kprobe_mutex);
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);
}
#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);
cpus_read_lock();
mutex_lock(&text_mutex);
__arm_kprobe(kp);
mutex_unlock(&text_mutex);
cpus_read_unlock();
return 0;
}
static int disarm_kprobe(struct kprobe *kp, bool reopt)
{
if (unlikely(kprobe_ftrace(kp)))
return disarm_kprobe_ftrace(kp);
cpus_read_lock();
mutex_lock(&text_mutex);
__disarm_kprobe(kp, reopt);
mutex_unlock(&text_mutex);
cpus_read_unlock();
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;
cpus_read_lock();
/* For preparing optimization, jump_label_text_reserved() is called */
jump_label_lock();
mutex_lock(&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) {
ret = -ENOMEM;
goto out;
}
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)
goto out;
}
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().
*/
goto out;
/* 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);
out:
mutex_unlock(&text_mutex);
jump_label_unlock();
cpus_read_unlock();
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))
goto invalid;
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 addr;
invalid:
return ERR_PTR(-EINVAL);
}
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) {
list_for_each_entry(list_p, &ap->list, list)
if (list_p == p)
/* kprobe p is a valid probe */
goto valid;
return NULL;
}
valid:
return ap;
}
/*
* 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)
{
int ret = 0;
mutex_lock(&kprobe_mutex);
if (WARN_ON_ONCE(__get_valid_kprobe(p)))
ret = -EINVAL;
mutex_unlock(&kprobe_mutex);
return ret;
}
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 /* !CONFIG_KPROBES_ON_FTRACE */
return -EINVAL;
#endif
}
return 0;
}
static int check_kprobe_address_safe(struct kprobe *p,
struct module **probed_mod)
{
int ret;
ret = check_ftrace_location(p);
if (ret)
return ret;
jump_label_lock();
preempt_disable();
/* Ensure it is not in reserved area nor out of text */
if (!(core_kernel_text((unsigned long) p->addr) ||
is_module_text_address((unsigned long) p->addr)) ||
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)) {
ret = -EINVAL;
goto out;
}
/* Check if 'p' is probing a module. */
*probed_mod = __module_text_address((unsigned long) p->addr);
if (*probed_mod) {
/*
* We must hold a refcount of the probed module while updating
* its code to prohibit unexpected unloading.
*/
if (unlikely(!try_module_get(*probed_mod))) {
ret = -ENOENT;
goto out;
}
/*
* If the module freed '.init.text', we couldn't insert
* kprobes in there.
*/
if (within_module_init((unsigned long)p->addr, *probed_mod) &&
(*probed_mod)->state != MODULE_STATE_COMING) {
module_put(*probed_mod);
*probed_mod = NULL;
ret = -ENOENT;
}
}
out:
preempt_enable();
jump_label_unlock();
return ret;
}
int register_kprobe(struct kprobe *p)
{
int ret;
struct kprobe *old_p;
struct module *probed_mod;
kprobe_opcode_t *addr;
bool on_func_entry;
/* Adjust 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;
p->nmissed = 0;
INIT_LIST_HEAD(&p->list);
ret = check_kprobe_address_safe(p, &probed_mod);
if (ret)
return ret;
mutex_lock(&kprobe_mutex);
if (on_func_entry)
p->flags |= KPROBE_FLAG_ON_FUNC_ENTRY;
old_p = get_kprobe(p->addr);
if (old_p) {
/* Since this may unoptimize 'old_p', locking 'text_mutex'. */
ret = register_aggr_kprobe(old_p, p);
goto out;
}
cpus_read_lock();
/* Prevent text modification */
mutex_lock(&text_mutex);
ret = prepare_kprobe(p);
mutex_unlock(&text_mutex);
cpus_read_unlock();
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 (!kprobes_all_disarmed && !kprobe_disabled(p)) {
ret = arm_kprobe(p);
if (ret) {
hlist_del_rcu(&p->hlist);
synchronize_rcu();
goto out;
}
}
/* Try to optimize kprobe */
try_to_optimize_kprobe(p);
out:
mutex_unlock(&kprobe_mutex);
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)) {
/* 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);
if (ap == p)
/*
* This probe is an independent(and non-optimized) kprobe
* (not an aggrprobe). Remove from the hash list.
*/
goto disarmed;
/* Following process expects this probe is an aggrprobe */
WARN_ON(!kprobe_aggrprobe(ap));
if (list_is_singular(&ap->list) && kprobe_disarmed(ap))
/*
* !disarmed could be happen if the probe is under delayed
* unoptimizing.
*/
goto disarmed;
else {
/* 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))
goto noclean;
}
ap->post_handler = NULL;
}
noclean:
/*
* 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;
disarmed:
hlist_del_rcu(&ap->hlist);
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;
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_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)
static void free_rp_inst_rcu(struct rcu_head *head)
{
struct kretprobe_instance *ri = container_of(head, struct kretprobe_instance, rcu);
if (refcount_dec_and_test(&ri->rph->ref))
kfree(ri->rph);
kfree(ri);
}
NOKPROBE_SYMBOL(free_rp_inst_rcu);
static void recycle_rp_inst(struct kretprobe_instance *ri)
{
struct kretprobe *rp = get_kretprobe(ri);
if (likely(rp))
freelist_add(&ri->freelist, &rp->freelist);
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_instance *ri;
struct freelist_node *node;
int count = 0;
node = rp->freelist.head;
while (node) {
ri = container_of(node, struct kretprobe_instance, freelist);
node = node->next;
kfree(ri);
count++;
}
if (refcount_sub_and_test(count, &rp->rph->ref)) {
kfree(rp->rph);
rp->rph = NULL;
}
}
/* 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 = NULL;
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)
{
kprobe_opcode_t *correct_ret_addr = NULL;
struct kretprobe_instance *ri = NULL;
struct llist_node *first, *node = NULL;
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_instance *ri;
struct freelist_node *fn;
fn = freelist_try_get(&rp->freelist);
if (!fn) {
rp->nmissed++;
return 0;
}
ri = container_of(fn, struct kretprobe_instance, freelist);
if (rp->entry_handler && rp->entry_handler(ri, regs)) {
freelist_add(&ri->freelist, &rp->freelist);
return 0;
}
arch_prepare_kretprobe(ri, regs);
__llist_add(&ri->llist, &current->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,
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;
struct kretprobe_instance *inst;
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) {
#ifdef CONFIG_PREEMPTION
rp->maxactive = max_t(unsigned int, 10, 2*num_possible_cpus());
#else
rp->maxactive = num_possible_cpus();
#endif
}
#ifdef CONFIG_KRETPROBE_ON_RETHOOK
rp->rh = rethook_alloc((void *)rp, kretprobe_rethook_handler);
if (!rp->rh)
return -ENOMEM;
for (i = 0; i < rp->maxactive; i++) {
inst = kzalloc(sizeof(struct kretprobe_instance) +
rp->data_size, GFP_KERNEL);
if (inst == NULL) {
rethook_free(rp->rh);
rp->rh = NULL;
return -ENOMEM;
}
rethook_add_node(rp->rh, &inst->node);
}
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->freelist.head = NULL;
rp->rph = kzalloc(sizeof(struct kretprobe_holder), GFP_KERNEL);
if (!rp->rph)
return -ENOMEM;
rp->rph->rp = rp;
for (i = 0; i < rp->maxactive; i++) {
inst = kzalloc(sizeof(struct kretprobe_instance) +
rp->data_size, GFP_KERNEL);
if (inst == NULL) {
refcount_set(&rp->rph->ref, i);
free_rp_inst(rp);
return -ENOMEM;
}
inst->rph = rp->rph;
freelist_add(&inst->freelist, &rp->freelist);
}
refcount_set(&rp->rph->ref, i);
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;
mutex_lock(&kprobe_mutex);
for (i = 0; i < num; i++) {
if (__unregister_kprobe_top(&rps[i]->kp) < 0)
rps[i]->kp.addr = NULL;
#ifdef CONFIG_KRETPROBE_ON_RETHOOK
rethook_free(rps[i]->rh);
#else
rps[i]->rph->rp = NULL;
#endif
}
mutex_unlock(&kprobe_mutex);
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);
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);
/*
* 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);
}
/* Disable one kprobe */
int disable_kprobe(struct kprobe *kp)
{
int ret = 0;
struct kprobe *p;
mutex_lock(&kprobe_mutex);
/* Disable this kprobe */
p = __disable_kprobe(kp);
if (IS_ERR(p))
ret = PTR_ERR(p);
mutex_unlock(&kprobe_mutex);
return ret;
}
EXPORT_SYMBOL_GPL(disable_kprobe);
/* Enable one kprobe */
int enable_kprobe(struct kprobe *kp)
{
int ret = 0;
struct kprobe *p;
mutex_lock(&kprobe_mutex);
/* Check whether specified probe is valid. */
p = __get_valid_kprobe(kp);
if (unlikely(p == NULL)) {
ret = -EINVAL;
goto out;
}
if (kprobe_gone(kp)) {
/* This kprobe has gone, we couldn't enable it. */
ret = -EINVAL;
goto out;
}
if (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;
}
out:
mutex_unlock(&kprobe_mutex);
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(sizeof(*ent), GFP_KERNEL);
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;
}
/* 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);
}
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();
}
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);
if (val == MODULE_STATE_COMING) {
mutex_lock(&kprobe_mutex);
add_module_kprobe_blacklist(mod);
mutex_unlock(&kprobe_mutex);
}
if (val != MODULE_STATE_GOING && val != MODULE_STATE_LIVE)
return NOTIFY_DONE;
/*
* When 'MODULE_STATE_GOING' was notified, both of module '.text' and
* '.init.text' sections would be freed. When 'MODULE_STATE_LIVE' was
* notified, only '.init.text' section would be freed. We need to
* disable kprobes which have been inserted in the sections.
*/
mutex_lock(&kprobe_mutex);
for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
head = &kprobe_table[i];
hlist_for_each_entry(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);
mutex_unlock(&kprobe_mutex);
return NOTIFY_DONE;
}
static struct notifier_block kprobe_module_nb = {
.notifier_call = kprobes_module_callback,
.priority = 0
};
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;
mutex_lock(&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);
}
}
mutex_unlock(&kprobe_mutex);
}
static int __init init_kprobes(void)
{
int i, err = 0;
/* 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;
#if defined(CONFIG_OPTPROBES) && defined(__ARCH_WANT_KPROBES_INSN_SLOT)
/* Init 'kprobe_optinsn_slots' for allocation */
kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE;
#endif
err = arch_init_kprobes();
if (!err)
err = register_die_notifier(&kprobe_exceptions_nb);
if (!err)
err = register_module_notifier(&kprobe_module_nb);
kprobes_initialized = (err == 0);
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_FS
static 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 = NULL;
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;
mutex_lock(&kprobe_mutex);
/* If kprobes are armed, just return */
if (!kprobes_all_disarmed)
goto already_enabled;
/*
* 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");
already_enabled:
mutex_unlock(&kprobe_mutex);
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;
mutex_lock(&kprobe_mutex);
/* If kprobes are already disarmed, just return */
if (kprobes_all_disarmed) {
mutex_unlock(&kprobe_mutex);
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");
mutex_unlock(&kprobe_mutex);
/* Wait for disarming all kprobes by optimizer */
wait_for_kprobe_optimizer();
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 */
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