| Message ID | 51b9752121c1c06197291ea6b395d163313ac6ea.1572010897.git.daniel@iogearbox.net |
|---|---|
| State | Changes Requested |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | Fix BPF probe memory helpers | expand |
On Fri, Oct 25, 2019 at 1:44 PM Daniel Borkmann <daniel@iogearbox.net> wrote: > > Convert the bpf_probe_write_user() helper to probe_user_write() such that > writes are not attempted under KERNEL_DS anymore which is buggy as kernel > and user space pointers can have overlapping addresses. Also, given we have > the access_ok() check inside probe_user_write(), the helper doesn't need > to do it twice. > > Fixes: 96ae52279594 ("bpf: Add bpf_probe_write_user BPF helper to be called in tracers") > Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> > --- Acked-by: Andrii Nakryiko <andriin@fb.com> [...]
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index c3240898cc44..79919a26cd59 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -163,7 +163,7 @@ static const struct bpf_func_proto bpf_probe_read_proto = { .arg3_type = ARG_ANYTHING, }; -BPF_CALL_3(bpf_probe_write_user, void *, unsafe_ptr, const void *, src, +BPF_CALL_3(bpf_probe_write_user, void __user *, unsafe_ptr, const void *, src, u32, size) { /* @@ -186,10 +186,8 @@ BPF_CALL_3(bpf_probe_write_user, void *, unsafe_ptr, const void *, src, return -EPERM; if (unlikely(!nmi_uaccess_okay())) return -EPERM; - if (!access_ok(unsafe_ptr, size)) - return -EPERM; - return probe_kernel_write(unsafe_ptr, src, size); + return probe_user_write(unsafe_ptr, src, size); } static const struct bpf_func_proto bpf_probe_write_user_proto = {
Convert the bpf_probe_write_user() helper to probe_user_write() such that writes are not attempted under KERNEL_DS anymore which is buggy as kernel and user space pointers can have overlapping addresses. Also, given we have the access_ok() check inside probe_user_write(), the helper doesn't need to do it twice. Fixes: 96ae52279594 ("bpf: Add bpf_probe_write_user BPF helper to be called in tracers") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> --- kernel/trace/bpf_trace.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-)