Messages in this thread | | | Date | Sat, 23 Jul 2016 18:13:52 -0700 | From | Alexei Starovoitov <> | Subject | Re: [PATCH net-next v5 1/2] bpf: Add bpf_probe_write_user BPF helper to be called in tracers |
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On Sat, Jul 23, 2016 at 05:43:48PM -0700, Sargun Dhillon wrote: > This allows user memory to be written to during the course of a kprobe. > It shouldn't be used to implement any kind of security mechanism > because of TOC-TOU attacks, but rather to debug, divert, and > manipulate execution of semi-cooperative processes. > > Although it uses probe_kernel_write, we limit the address space > the probe can write into by checking the space with access_ok. > This is so the call doesn't sleep. In addition we ensure the threads's > current fs / segment is USER_DS and the thread isn't exiting nor > a kernel thread. > > Given this feature is experimental, and has the risk of crashing the > system, we print a warning on first invocation, and the process name > on subsequent invocations. > > It was tested with the tracex7 program on x86-64.
s/tracex7/test_probe_write_user form the next patch/ or just drop this sentence.
> +static const struct bpf_func_proto *bpf_get_probe_write_proto(void) { > + pr_warn_ratelimited("bpf_probe_write_user: %s[%d] installing program with helper: it may corrupt user memory!", > + current->comm, task_pid_nr(current));
I think checkpatch should have complained here. current->comm line should start under "
No other nits for this patch :) Once fixed, feel free to add my Acked-by: Alexei Starovoitov <ast@kernel.org>
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