Re: [PATCH net-next v2] net: bpf: make eBPF interpreter images read-only

[Alexei Starovoitov]

On Tue, Sep 2, 2014 at 1:53 PM, Hannes Frederic Sowa
<hannes@xxxxxxxxxxxxxxxxxxx> wrote:
> From: Daniel Borkmann <dborkman@xxxxxxxxxx>
>
> With eBPF getting more extended and exposure to user space is on it's way,
> hardening the memory range the interpreter uses to steer its command flow
> seems appropriate.  This patch moves the to be interpreted bytecode to
> read-only pages.
...
>  11 files changed, 144 insertions(+), 32 deletions(-)

nice. quite short.

> +#ifdef CONFIG_DEBUG_SET_MODULE_RONX
> +static inline void bpf_prog_lock_ro(struct bpf_prog *fp)
> +{
> +       set_memory_ro((unsigned long)fp, fp->pages);

since ronx are ifdef checked together,
would probably make sense to set nx too?

> +static inline void bpf_prog_unlock_ro(struct bpf_prog *fp)
> +{
> +       set_memory_rw((unsigned long)fp, fp->pages);

why rw is needed?
since fp is allocated with vmalloc, vfree doesn't need
to touch the pages to free them, no?
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/