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 <[email protected]>
---
include/linux/uprobes.h | 9 +++++++++
kernel/events/uprobes.c | 18 +++++++++++-------
2 files changed, 20 insertions(+), 7 deletions(-)
diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
index 83742b9..c2df693 100644
--- a/include/linux/uprobes.h
+++ b/include/linux/uprobes.h
@@ -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;
};
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 60b0a90..e2ebb6f 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -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);
}
--
1.5.5.1
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