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Commit fb1a59fa authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Ingo Molnar
Browse files

kprobes: Blacklist symbols in arch-defined prohibited area 



Blacklist symbols in arch-defined probe-prohibited areas.
With this change, user can see all symbols which are prohibited
to probe in debugfs.

All archtectures which have custom prohibit areas should define
its own arch_populate_kprobe_blacklist() function, but unless that,
all symbols marked __kprobes are blacklisted.

Reported-by: default avatarAndrea Righi <righi.andrea@gmail.com>
Tested-by: default avatarAndrea Righi <righi.andrea@gmail.com>
Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: David S. Miller <davem@davemloft.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yonghong Song <yhs@fb.com>
Link: http://lkml.kernel.org/r/154503485491.26176.15823229545155174796.stgit@devbox


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 76aea1ee

include/linux/kprobes.h

+3 −0
Original line number Diff line number Diff line
@@ -242,10 +242,13 @@ extern int arch_init_kprobes(void); 
extern void show_registers(struct pt_regs *regs);

extern void kprobes_inc_nmissed_count(struct kprobe *p);

extern bool arch_within_kprobe_blacklist(unsigned long addr);

extern int arch_populate_kprobe_blacklist(void);

extern bool arch_kprobe_on_func_entry(unsigned long offset);

extern bool kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset);



extern bool within_kprobe_blacklist(unsigned long addr);

extern int kprobe_add_ksym_blacklist(unsigned long entry);

extern int kprobe_add_area_blacklist(unsigned long start, unsigned long end);



struct kprobe_insn_cache {

	struct mutex mutex;

kernel/kprobes.c

+53 −14
Original line number Diff line number Diff line
@@ -2093,6 +2093,47 @@ void dump_kprobe(struct kprobe *kp) 
}

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;

}



int __init __weak arch_populate_kprobe_blacklist(void)

{

	return 0;

}



/*

 * Lookup and populate the kprobe_blacklist.

 *
@@ -2104,26 +2145,24 @@ NOKPROBE_SYMBOL(dump_kprobe); 
static int __init populate_kprobe_blacklist(unsigned long *start,

					     unsigned long *end)

{

	unsigned long entry;

	unsigned long *iter;

	struct kprobe_blacklist_entry *ent;

	unsigned long entry, offset = 0, size = 0;

	int ret;



	for (iter = start; iter < end; iter++) {

		entry = arch_deref_entry_point((void *)*iter);



		if (!kernel_text_address(entry) ||

		    !kallsyms_lookup_size_offset(entry, &size, &offset))

		ret = kprobe_add_ksym_blacklist(entry);

		if (ret == -EINVAL)

			continue;



		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);

		if (ret < 0)

			return ret;

	}

	return 0;



	/* Symbols in __kprobes_text are blacklisted */

	ret = kprobe_add_area_blacklist((unsigned long)__kprobes_text_start,

					(unsigned long)__kprobes_text_end);



	return ret ? : arch_populate_kprobe_blacklist();

}



/* Module notifier call back, checking kprobes on the module */