From 8a7f2fa0dea3b019500961b86d765e6fdd4bffb2 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Fri, 28 Dec 2012 17:58:38 +0100 Subject: [PATCH] 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 Acked-by: Srikar Dronamraju --- 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 83742b91ff73..c2df6934fdc6 100644 --- a/include/linux/uprobes.h +++ b/include/linux/uprobes.h @@ -35,8 +35,17 @@ struct inode; # include #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 33912086d54e..c2737be3c4b8 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); }