Hi Sean,
On 06/14/2018 08:42 PM, Sean Young wrote:
> If the kernel is compiled with CONFIG_CGROUP_BPF not enabled, it is not
> possible to attach, detach or query IR BPF programs to /dev/lircN devices,
> making them impossible to use. For embedded devices, it should be possible
> to use IR decoding without cgroups or CONFIG_CGROUP_BPF enabled.
>
> This change requires some refactoring, since bpf_prog_{attach,detach,query}
> functions are now always compiled, but their code paths for cgroups need
> moving out. Rather than a #ifdef CONFIG_CGROUP_BPF in kernel/bpf/syscall.c,
> moving them to kernel/bpf/cgroup.c does not require #ifdefs since that file
> is already conditionally compiled.
>
> Signed-off-by: Sean Young <sean@xxxxxxxx>
Just two minor edits below from my side:
> include/linux/bpf-cgroup.h | 31 +++++++++++
> kernel/bpf/cgroup.c | 110 +++++++++++++++++++++++++++++++++++++
> kernel/bpf/syscall.c | 105 ++---------------------------------
> 3 files changed, 145 insertions(+), 101 deletions(-)
>
> diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h
> index 975fb4cf1bb7..ee67cd35f426 100644
> --- a/include/linux/bpf-cgroup.h
> +++ b/include/linux/bpf-cgroup.h
> @@ -188,12 +188,43 @@ int __cgroup_bpf_check_dev_permission(short dev_type, u32 major, u32 minor,
> \
> __ret; \
> })
> +int sockmap_get_from_fd(const union bpf_attr *attr, int type, bool attach);
> +int cgroup_bpf_prog_attach(const union bpf_attr *attr,
> + enum bpf_prog_type ptype);
> +int cgroup_bpf_prog_detach(const union bpf_attr *attr,
> + enum bpf_prog_type ptype);
> +int cgroup_bpf_prog_query(const union bpf_attr *attr,
> + union bpf_attr __user *uattr);
> #else
>
> struct cgroup_bpf {};
> static inline void cgroup_bpf_put(struct cgroup *cgrp) {}
> static inline int cgroup_bpf_inherit(struct cgroup *cgrp) { return 0; }
>
> +static inline int sockmap_get_from_fd(const union bpf_attr *attr,
> + int type, bool attach)
> +{
> + return -EINVAL;
> +}
> +
> +static inline int cgroup_bpf_prog_attach(const union bpf_attr *attr,
> + enum bpf_prog_type ptype)
> +{
> + return -EINVAL;
> +}
> +
> +static inline int cgroup_bpf_prog_detach(const union bpf_attr *attr,
> + enum bpf_prog_type ptype)
> +{
> + return -EINVAL;
> +}
> +
> +static inline int cgroup_bpf_prog_query(const union bpf_attr *attr,
> + union bpf_attr __user *uattr)
> +{
> + return -EINVAL;
> +}
> +
> #define cgroup_bpf_enabled (0)
> #define BPF_CGROUP_PRE_CONNECT_ENABLED(sk) (0)
> #define BPF_CGROUP_RUN_PROG_INET_INGRESS(sk,skb) ({ 0; })
> diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
> index f7c00bd6f8e4..d6e18f9dc0c4 100644
> --- a/kernel/bpf/cgroup.c
> +++ b/kernel/bpf/cgroup.c
> @@ -428,6 +428,116 @@ int __cgroup_bpf_query(struct cgroup *cgrp, const union bpf_attr *attr,
> return ret;
> }
>
> +int bpf_prog_attach_check_attach_type(const struct bpf_prog *prog,
> + enum bpf_attach_type attach_type)
> +{
> + switch (prog->type) {
> + case BPF_PROG_TYPE_CGROUP_SOCK:
> + case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
> + return attach_type == prog->expected_attach_type ? 0 : -EINVAL;
> + default:
> + return 0;
> + }
> +}
This one is rather BPF core, cgroup progs only happen to use it. Could
you either move it as static inline into include/linux/bpf.h or leave it
in kernel/bpf/syscall.c? In any case the #ifdef CONFIG_CGROUP_BPF wrapper
could probably be dropped as well from it.
> +int sockmap_get_from_fd(const union bpf_attr *attr, int type, bool attach)
> +{
> + struct bpf_prog *prog = NULL;
> + int ufd = attr->target_fd;
> + struct bpf_map *map;
> + struct fd f;
> + int err;
> +
> + f = fdget(ufd);
> + map = __bpf_map_get(f);
> + if (IS_ERR(map))
> + return PTR_ERR(map);
> +
> + if (attach) {
> + prog = bpf_prog_get_type(attr->attach_bpf_fd, type);
> + if (IS_ERR(prog)) {
> + fdput(f);
> + return PTR_ERR(prog);
> + }
> + }
> +
> + err = sock_map_prog(map, prog, attr->attach_type);
> + if (err) {
> + fdput(f);
> + if (prog)
> + bpf_prog_put(prog);
> + return err;
> + }
> +
> + fdput(f);
> + return 0;
> +}
And this one should rather end up in kernel/bpf/sockmap.c to have it with
the rest of sockmap code. Moving into cgroup.c would rather be a in the
wrong place given what the code does.
Thanks,
Daniel
