Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx> writes: > On Tue, Feb 25, 2025 at 11:06 PM Song Liu <song@xxxxxxxxxx> wrote: >> >> On Tue, Feb 25, 2025 at 4:31 PM Blaise Boscaccy >> <bboscaccy@xxxxxxxxxxxxxxxxxxx> wrote: >> > >> > Certain bpf syscall subcommands are available for usage from both >> > userspace and the kernel. LSM modules or eBPF gatekeeper programs may >> > need to take a different course of action depending on whether or not >> > a BPF syscall originated from the kernel or userspace. >> > >> > Additionally, some of the bpf_attr struct fields contain pointers to >> > arbitrary memory. Currently the functionality to determine whether or >> > not a pointer refers to kernel memory or userspace memory is exposed >> > to the bpf verifier, but that information is missing from various LSM >> > hooks. >> > >> > Here we augment the LSM hooks to provide this data, by simply passing >> > the corresponding universal pointer in any hook that contains already >> > contains a bpf_attr struct that corresponds to a subcommand that may >> > be called from the kernel. >> >> I think this information is useful for LSM hooks. >> >> Question: Do we need a full bpfptr_t for these hooks, or just a boolean >> "is_kernel or not"? > > +1 > Just passing the bool should do. > Passing uattr is a footgun. Last thing we need is to open up TOCTOU concerns. Sounds good to me, I'll rework it to use a bool instead. -blaise
