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static_call: Avoid kprobes on inline static_call()s

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Similar to how we disallow kprobes on any other dynamic text
(ftrace/jump_label) also disallow kprobes on inline static_call()s.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20200818135804.744920586@infradead.org
This commit is contained in:
Peter Zijlstra 2020-08-18 15:57:43 +02:00 committed by Ingo Molnar
parent 9183c3f9ed
commit 6333e8f73b
4 changed files with 84 additions and 1 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

4
arch/x86/kernel/kprobes/opt.c
View file

@ -18,6 +18,7 @@
#include <linux/ftrace.h>
#include <linux/frame.h>
#include <linux/pgtable.h>
#include <linux/static_call.h>
#include <asm/text-patching.h>
#include <asm/cacheflush.h>
@ -210,7 +211,8 @@ static int copy_optimized_instructions(u8 *dest, u8 *src, u8 *real)
/* Check whether the address range is reserved */
if (ftrace_text_reserved(src, src + len - 1) ||
alternatives_text_reserved(src, src + len - 1) ||
jump_label_text_reserved(src, src + len - 1))
jump_label_text_reserved(src, src + len - 1) ||
static_call_text_reserved(src, src + len - 1))
return -EBUSY;
return len;

11
include/linux/static_call.h
View file

@ -110,6 +110,7 @@ struct static_call_key {
extern void __static_call_update(struct static_call_key *key, void *tramp, void *func);
extern int static_call_mod_init(struct module *mod);
extern int static_call_text_reserved(void *start, void *end);
#define DEFINE_STATIC_CALL(name, _func) \
DECLARE_STATIC_CALL(name, _func); \
@ -153,6 +154,11 @@ void __static_call_update(struct static_call_key *key, void *tramp, void *func)
cpus_read_unlock();
}
static inline int static_call_text_reserved(void *start, void *end)
{
return 0;
}
#define EXPORT_STATIC_CALL(name) \
EXPORT_SYMBOL(STATIC_CALL_KEY(name)); \
EXPORT_SYMBOL(STATIC_CALL_TRAMP(name))
@ -182,6 +188,11 @@ void __static_call_update(struct static_call_key *key, void *tramp, void *func)
WRITE_ONCE(key->func, func);
}
static inline int static_call_text_reserved(void *start, void *end)
{
return 0;
}
#define EXPORT_STATIC_CALL(name) EXPORT_SYMBOL(STATIC_CALL_KEY(name))
#define EXPORT_STATIC_CALL_GPL(name) EXPORT_SYMBOL_GPL(STATIC_CALL_KEY(name))

2
kernel/kprobes.c
View file

@ -36,6 +36,7 @@
#include <linux/cpu.h>
#include <linux/jump_label.h>
#include <linux/perf_event.h>
#include <linux/static_call.h>
#include <asm/sections.h>
#include <asm/cacheflush.h>
@ -1634,6 +1635,7 @@ static int check_kprobe_address_safe(struct kprobe *p,
if (!kernel_text_address((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;

68
kernel/static_call.c
View file

@ -204,8 +204,58 @@ static int __static_call_init(struct module *mod,
return 0;
}
static int addr_conflict(struct static_call_site *site, void *start, void *end)
{
unsigned long addr = (unsigned long)static_call_addr(site);
if (addr <= (unsigned long)end &&
addr + CALL_INSN_SIZE > (unsigned long)start)
return 1;
return 0;
}
static int __static_call_text_reserved(struct static_call_site *iter_start,
struct static_call_site *iter_stop,
void *start, void *end)
{
struct static_call_site *iter = iter_start;
while (iter < iter_stop) {
if (addr_conflict(iter, start, end))
return 1;
iter++;
}
return 0;
}
#ifdef CONFIG_MODULES
static int __static_call_mod_text_reserved(void *start, void *end)
{
struct module *mod;
int ret;
preempt_disable();
mod = __module_text_address((unsigned long)start);
WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
if (!try_module_get(mod))
mod = NULL;
preempt_enable();
if (!mod)
return 0;
ret = __static_call_text_reserved(mod->static_call_sites,
mod->static_call_sites + mod->num_static_call_sites,
start, end);
module_put(mod);
return ret;
}
static int static_call_add_module(struct module *mod)
{
return __static_call_init(mod, mod->static_call_sites,
@ -273,8 +323,26 @@ static struct notifier_block static_call_module_nb = {
.notifier_call = static_call_module_notify,
};
#else
static inline int __static_call_mod_text_reserved(void *start, void *end)
{
return 0;
}
#endif /* CONFIG_MODULES */
int static_call_text_reserved(void *start, void *end)
{
int ret = __static_call_text_reserved(__start_static_call_sites,
__stop_static_call_sites, start, end);
if (ret)
return ret;
return __static_call_mod_text_reserved(start, end);
}
static void __init static_call_init(void)
{
int ret;