On Thu, Dec 03, 2020 at 10:33:28PM +0100, Florent Revest wrote: > This creates a new helper proto because the existing > bpf_get_socket_cookie_sock_proto has a ARG_PTR_TO_CTX argument and only > works for BPF programs where the context is a sock. > > This helper could also be useful to other BPF program types such as LSM. > > Signed-off-by: Florent Revest <[email protected]> > --- > include/uapi/linux/bpf.h | 7 +++++++ > kernel/trace/bpf_trace.c | 4 ++++ > net/core/filter.c | 7 +++++++ > tools/include/uapi/linux/bpf.h | 7 +++++++ > 4 files changed, 25 insertions(+) > > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h > index c3458ec1f30a..3e0e33c43998 100644 > --- a/include/uapi/linux/bpf.h > +++ b/include/uapi/linux/bpf.h > @@ -1662,6 +1662,13 @@ union bpf_attr { > * Return > * A 8-byte long non-decreasing number. > * > + * u64 bpf_get_socket_cookie(void *sk) > + * Description > + * Equivalent to **bpf_get_socket_cookie**\ () helper that accepts > + * *sk*, but gets socket from a BTF **struct sock**. > + * Return > + * A 8-byte long non-decreasing number. > + * > * u32 bpf_get_socket_uid(struct sk_buff *skb) > * Return > * The owner UID of the socket associated to *skb*. If the socket > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c > index d255bc9b2bfa..14ad96579813 100644 > --- a/kernel/trace/bpf_trace.c > +++ b/kernel/trace/bpf_trace.c > @@ -1725,6 +1725,8 @@ raw_tp_prog_func_proto(enum bpf_func_id func_id, const > struct bpf_prog *prog) > } > } > > +extern const struct bpf_func_proto bpf_get_socket_cookie_sock_tracing_proto; > + > const struct bpf_func_proto * > tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog > *prog) > { > @@ -1748,6 +1750,8 @@ tracing_prog_func_proto(enum bpf_func_id func_id, const > struct bpf_prog *prog) > return &bpf_sk_storage_get_tracing_proto; > case BPF_FUNC_sk_storage_delete: > return &bpf_sk_storage_delete_tracing_proto; > + case BPF_FUNC_get_socket_cookie: > + return &bpf_get_socket_cookie_sock_tracing_proto; > #endif > case BPF_FUNC_seq_printf: > return prog->expected_attach_type == BPF_TRACE_ITER ? > diff --git a/net/core/filter.c b/net/core/filter.c > index 2ca5eecebacf..177c4e5e529d 100644 > --- a/net/core/filter.c > +++ b/net/core/filter.c > @@ -4631,6 +4631,13 @@ static const struct bpf_func_proto > bpf_get_socket_cookie_sock_proto = { > .arg1_type = ARG_PTR_TO_CTX, > }; > > +const struct bpf_func_proto bpf_get_socket_cookie_sock_tracing_proto = { > + .func = bpf_get_socket_cookie_sock, > + .gpl_only = false, > + .ret_type = RET_INTEGER, > + .arg1_type = ARG_PTR_TO_BTF_ID_SOCK_COMMON, In tracing where it gets a sk pointer, the sk could be NULL. A NULL check is required in the helper. Please refer to bpf_skc_to_tcp_sock[_proto] as an example.
This proto is in general also useful for non tracing context where it can get a hold of a sk pointer. (e.g. another similar usage that will have a hold on a sk pointer for BPF_PROG_TYPE_SK_REUSEPORT [0]). In case if you don't need sleepable at this point as Daniel mentioned in another thread. Does it make sense to rename this proto to something like bpf_get_socket_pointer_cookie_proto? [0]: https://lore.kernel.org/bpf/[email protected]/
