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. Best -- Lorenz Bauer | Systems Engineer 6th Floor, County Hall/The Riverside Building, SE1 7PB, UK www.cloudflare.com
