Commit 8a7f2fa0 authored by Oleg Nesterov's avatar Oleg Nesterov
Browse files

uprobes: Reintroduce uprobe_consumer->filter() 

Finally add uprobe_consumer->filter() and change consumer_filter()
to actually call this method.

Note that ->filter() accepts mm_struct, not task_struct. Because:

	1. We do not have for_each_mm_user(mm, task).

	2. Even if we implement for_each_mm_user(), ->filter() can
	   use it itself.

	3. It is not clear who will actually need this interface to
	   do the "nontrivial" filtering.

Another argument is "enum uprobe_filter_ctx", consumer->filter() can
use it to figure out why/where it was called. For example, perhaps
we can add UPROBE_FILTER_PRE_REGISTER used by build_map_info() to
quickly "nack" the unwanted mm's. In this case consumer should know
that it is called under ->i_mmap_mutex.

See the previous discussion at http://marc.info/?t=135214229700002


Perhaps we should pass more arguments, vma/vaddr?

Note: this patch obviously can't help to filter out the child created
by fork(), this will be addressed later.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Acked-by: default avatarSrikar Dronamraju <srikar@linux.vnet.ibm.com>
parent 806a98bd

include/linux/uprobes.h

+9 −0
Original line number Diff line number Diff line
@@ -35,8 +35,17 @@ struct inode; 
# include <asm/uprobes.h>

#endif



enum uprobe_filter_ctx {

	UPROBE_FILTER_REGISTER,

	UPROBE_FILTER_UNREGISTER,

	UPROBE_FILTER_MMAP,

};



struct uprobe_consumer {

	int (*handler)(struct uprobe_consumer *self, struct pt_regs *regs);

	bool (*filter)(struct uprobe_consumer *self,

				enum uprobe_filter_ctx ctx,

				struct mm_struct *mm);



	struct uprobe_consumer *next;

};

kernel/events/uprobes.c

+11 −7
Original line number Diff line number Diff line
@@ -579,19 +579,21 @@ static int prepare_uprobe(struct uprobe *uprobe, struct file *file, 
	return ret;

}



static inline bool consumer_filter(struct uprobe_consumer *uc)

static inline bool consumer_filter(struct uprobe_consumer *uc,

				   enum uprobe_filter_ctx ctx, struct mm_struct *mm)

{

	return true; /* TODO: !uc->filter || uc->filter(...) */

	return !uc->filter || uc->filter(uc, ctx, mm);

}



static bool filter_chain(struct uprobe *uprobe)

static bool filter_chain(struct uprobe *uprobe,

			 enum uprobe_filter_ctx ctx, struct mm_struct *mm)

{

	struct uprobe_consumer *uc;

	bool ret = false;



	down_read(&uprobe->consumer_rwsem);

	for (uc = uprobe->consumers; uc; uc = uc->next) {

		ret = consumer_filter(uc);

		ret = consumer_filter(uc, ctx, mm);

		if (ret)

			break;

	}
@@ -772,10 +774,12 @@ static int register_for_each_vma(struct uprobe *uprobe, bool is_register) 


		if (is_register) {

			/* consult only the "caller", new consumer. */

			if (consumer_filter(uprobe->consumers))

			if (consumer_filter(uprobe->consumers,

					UPROBE_FILTER_REGISTER, mm))

				err = install_breakpoint(uprobe, mm, vma, info->vaddr);

		} else if (test_bit(MMF_HAS_UPROBES, &mm->flags)) {

			if (!filter_chain(uprobe))

			if (!filter_chain(uprobe,

					UPROBE_FILTER_UNREGISTER, mm))

				err |= remove_breakpoint(uprobe, mm, info->vaddr);

		}
@@ -968,7 +972,7 @@ int uprobe_mmap(struct vm_area_struct *vma) 
	 */

	list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) {

		if (!fatal_signal_pending(current) &&

		    filter_chain(uprobe)) {

		    filter_chain(uprobe, UPROBE_FILTER_MMAP, vma->vm_mm)) {

			unsigned long vaddr = offset_to_vaddr(vma, uprobe->offset);

			install_breakpoint(uprobe, vma->vm_mm, vma, vaddr);

		}

CRA Git | Maintained and supported by SUSTech CRA and CCSE