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SubjectRe: [PATCH] kprobes: x86_64: blacklist non-attachable interrupt functions
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 <mhiramat@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.
>
> Reported-by: Andrea Righi <righi.andrea@gmail.com>
> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
> ---

[snip]

> +int kprobe_add_ksym_blacklist(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 - offset;
> + ent->end_addr = entry - offset + size;

Do we need to take offset into account? The code before wasn't using it.

> + INIT_LIST_HEAD(&ent->list);
> + list_add_tail(&ent->list, &kprobe_blacklist);
> +
> + return (int)size;
> +}
> +
> +/* Add functions in arch defined probe-prohibited area */
> +int __weak arch_populate_kprobe_blacklist(void)
> +{
> + unsigned long entry;
> + int ret = 0;
> +
> + for (entry = (unsigned long)__kprobes_text_start;
> + entry < (unsigned long)__kprobes_text_end;
> + entry += ret) {
> + ret = kprobe_add_ksym_blacklist(entry);
> + if (ret < 0)
> + return ret;
> + if (ret == 0) /* In case of alias symbol */
> + ret = 1;
> + }
> + return 0;
> +}
> +
> /*
> * Lookup and populate the kprobe_blacklist.
> *
> @@ -2104,26 +2142,20 @@ NOKPROBE_SYMBOL(dump_kprobe);
> static int __init populate_kprobe_blacklist(unsigned long *start,
> unsigned long *end)
> {
> + unsigned long entry;
> unsigned long *iter;
> - struct kprobe_blacklist_entry *ent;
> - unsigned long entry, offset = 0, size = 0;
> + int ret;
>
> 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_add_ksym_blacklist(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;
> +
> + return arch_populate_kprobe_blacklist();
> }
>
> /* Module notifier call back, checking kprobes on the module */

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