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uprobes: Reintroduce uprobe_consumer->filter()

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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: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
This commit is contained in:
Oleg Nesterov 2012-12-28 17:58:38 +01:00
parent 806a98bdf2
commit 8a7f2fa0de
2 changed files with 20 additions and 7 deletions
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9
include/linux/uprobes.h
View File

@ -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;
};

18
kernel/events/uprobes.c
View File

@ -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);
}