On Wed, Mar 31, 2021 at 7:04 AM Lorenz Bauer <lmb@xxxxxxxxxxxxxx> wrote: > > On Fri, 26 Mar 2021 at 16:05, Lorenz Bauer <lmb@xxxxxxxxxxxxxx> wrote: > > > > Invoking BPF_OBJ_GET on a pinned bpf_link checks the path access > > permissions based on file_flags, but the returned fd ignores flags. > > This means that any user can acquire a "read-write" fd for a pinned > > link with mode 0664 by invoking BPF_OBJ_GET with BPF_F_RDONLY in > > file_flags. The fd can be used to invoke BPF_LINK_DETACH, etc. > > > > Fix this by refusing non-O_RDWR flags in BPF_OBJ_GET. This works > > because OBJ_GET by default returns a read write mapping and libbpf > > doesn't expose a way to override this behaviour for programs > > and links. > > Hi Alexei and Daniel, > > I think these two patches might have fallen through the cracks, could > you take a look? I'm not sure what the etiquette is around bumping a > set, so please let me know if you'd prefer me to send the patches with > acks included or something like that. It is still in patchworks. I didn't have time to think it through. Sorry for delay.
