Commit 6333e8f7 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

static_call: Avoid kprobes on inline static_call()s 



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: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20200818135804.744920586@infradead.org
parent 9183c3f9

arch/x86/kernel/kprobes/opt.c

+3 −1
Original line number Diff line number Diff line
@@ -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;

include/linux/static_call.h

+11 −0
Original line number Diff line number Diff line
@@ -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))

kernel/kprobes.c

+2 −0
Original line number Diff line number Diff line
@@ -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;

kernel/static_call.c

+68 −0
Original line number Diff line number Diff line
@@ -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;