On Fri, 7 Dec 2018 18:58:05 +0100 Andrea Righi <righi.and...@gmail.com> wrote:
> On Sat, Dec 08, 2018 at 01:01:20AM +0900, Masami Hiramatsu wrote: > > Hi Andrea and Ingo, > > > > Here is the patch what I meant. I just ran it on qemu-x86, and seemed > > working. > > After introducing this patch, I will start adding > > arch_populate_kprobe_blacklist() > > to some arches. > > > > Thank you, > > > > [RFC] kprobes: x86/kprobes: Blacklist symbols in arch-defined prohibited > > area > > > > From: Masami Hiramatsu <mhira...@kernel.org> > > > > Blacklist symbols in arch-defined probe-prohibited areas. > > With this change, user can see all symbols which are prohibited > > to probe in debugfs. > > > > All archtectures which have custom prohibit areas should define > > its own arch_populate_kprobe_blacklist() function, but unless that, > > all symbols marked __kprobes are blacklisted. > > What about iterating all symbols and use arch_within_kprobe_blacklist() > to check if we need to blacklist them or not. Sorry, I don't want to iterate all ksyms since it may take a long time (especially embedded small devices.) > > In this way we don't have to introduce an > arch_populate_kprobe_blacklist() for each architecture. Hmm, I had a same idea, but there are some arch which prohibit probing extable entries (e.g. arm64.) For correctness of the blacklist, I think it should be listed (not entire the function body). I also rather like to remove arch_within_kprobe_blacklist() instead. Thank you, > > Something like the following maybe. > > Thanks. > > [RFC] kprobes: blacklist all symbols in arch-defined prohibited area > > From: Andrea Righi <righi.and...@gmail.com> > > Blacklist symbols in arch-defined probe-prohibited areas. > With this change, user can see all symbols which are prohibited > to probe in debugfs. > > Signed-off-by: Masami Hiramatsu <mhira...@kernel.org> > Signed-off-by: Andrea Righi <righi.and...@gmail.com> > --- > kernel/kprobes.c | 55 +++++++++++++++++++++++++++++++++++++++++-------------- > 1 file changed, 41 insertions(+), 14 deletions(-) > > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > index 90e98e233647..e67598dd7468 100644 > --- a/kernel/kprobes.c > +++ b/kernel/kprobes.c > @@ -2093,6 +2093,35 @@ void dump_kprobe(struct kprobe *kp) > } > NOKPROBE_SYMBOL(dump_kprobe); > > +static int kprobe_blacklist_add(unsigned long entry) > +{ > + struct kprobe_blacklist_entry *ent; > + unsigned long offset = 0, size = 0; > + > + if (!kernel_text_address(entry) || > + !kallsyms_lookup_size_offset(entry, &size, &offset)) > + return -EINVAL; > + > + ent = kmalloc(sizeof(*ent), GFP_KERNEL); > + if (!ent) > + return -ENOMEM; > + ent->start_addr = entry; > + ent->end_addr = entry + size; > + INIT_LIST_HEAD(&ent->list); > + list_add_tail(&ent->list, &kprobe_blacklist); > + > + return 0; > +} > + > +static int arch_populate_kprobe_blacklist(void *data, const char *name, > + struct module *mod, > + unsigned long entry) > +{ > + if (arch_within_kprobe_blacklist(entry)) > + kprobe_blacklist_add(entry); > + return 0; > +} > + > /* > * Lookup and populate the kprobe_blacklist. > * > @@ -2104,24 +2133,22 @@ NOKPROBE_SYMBOL(dump_kprobe); > static int __init populate_kprobe_blacklist(unsigned long *start, > unsigned long *end) > { > - unsigned long *iter; > - struct kprobe_blacklist_entry *ent; > - unsigned long entry, offset = 0, size = 0; > + unsigned long entry, *iter; > + int ret; > > + /* Blacklist all arch_within_kprobe_blacklist() symbols */ > + mutex_lock(&module_mutex); > + kallsyms_on_each_symbol(arch_populate_kprobe_blacklist, NULL); > + mutex_unlock(&module_mutex); > + > + /* Add explicitly blacklisted symbols */ > for (iter = start; iter < end; iter++) { > entry = arch_deref_entry_point((void *)*iter); > - > - if (!kernel_text_address(entry) || > - !kallsyms_lookup_size_offset(entry, &size, &offset)) > + ret = kprobe_blacklist_add(entry); > + if (ret == -EINVAL) > continue; > - > - ent = kmalloc(sizeof(*ent), GFP_KERNEL); > - if (!ent) > - return -ENOMEM; > - ent->start_addr = entry; > - ent->end_addr = entry + size; > - INIT_LIST_HEAD(&ent->list); > - list_add_tail(&ent->list, &kprobe_blacklist); > + if (ret < 0) > + return ret; > } > return 0; > } -- Masami Hiramatsu <mhira...@kernel.org>