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: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 3391208..c2737be 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -579,19 +579,21 @@
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 @@
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 @@
*/
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);
}