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From:   Y Song <ys114321@gmail.com>
Date:   Thu, 7 Jun 2018 11:14:41 -0700
Message-ID: <CAH3MdRXE8=dE25Sj3TPDzVh7ytnvCkUDvCDzZkEZe0N84dy-Zw@mail.gmail.com>
Subject: Re: [PATCH] bpf: attach type BPF_LIRC_MODE2 should not depend on CONFIG_BPF_CGROUP
To:     Sean Young <sean@mess.org>
Cc:     Daniel Borkmann <daniel@iogearbox.net>,
        Matthias Reichl <hias@horus.com>, linux-media@vger.kernel.org,
        LKML <linux-kernel@vger.kernel.org>,
        Alexei Starovoitov <ast@kernel.org>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        netdev <netdev@vger.kernel.org>,
        Devin Heitmueller <dheitmueller@kernellabs.com>,
        Quentin Monnet <quentin.monnet@netronome.com>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Wed, Jun 6, 2018 at 2:09 PM, Sean Young <sean@mess.org> wrote:
> Compile bpf_prog_{attach,detach,query} even if CONFIG_BPF_CGROUP is not
> set.

It should be CONFIG_CGROUP_BPF here. The same for subject line.
Today, if CONFIG_CGROUP_BPF is not defined. Users will get an -EINVAL
if they try to attach/detach/query.

I am not sure what is the motivation behind this change. Could you explain more?

>
> Signed-off-by: Sean Young <sean@mess.org>
> ---
>  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;
> +       }
> +}
> +
> +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;
> +}
> +
> +int cgroup_bpf_prog_attach(const union bpf_attr *attr, enum bpf_prog_type ptype)
> +{
> +       struct bpf_prog *prog;
> +       struct cgroup *cgrp;
> +       int ret;
> +
> +       prog = bpf_prog_get_type(attr->attach_bpf_fd, ptype);
> +       if (IS_ERR(prog))
> +               return PTR_ERR(prog);
> +
> +       if (bpf_prog_attach_check_attach_type(prog, attr->attach_type)) {
> +               bpf_prog_put(prog);
> +               return -EINVAL;
> +       }
> +
> +       cgrp = cgroup_get_from_fd(attr->target_fd);
> +       if (IS_ERR(cgrp)) {
> +               bpf_prog_put(prog);
> +               return PTR_ERR(cgrp);
> +       }
> +
> +       ret = cgroup_bpf_attach(cgrp, prog, attr->attach_type,
> +                               attr->attach_flags);
> +       if (ret)
> +               bpf_prog_put(prog);
> +       cgroup_put(cgrp);
> +
> +       return ret;
> +}
> +
> +int cgroup_bpf_prog_detach(const union bpf_attr *attr, enum bpf_prog_type ptype)
> +{
> +       struct bpf_prog *prog;
> +       struct cgroup *cgrp;
> +       int ret;
> +
> +       cgrp = cgroup_get_from_fd(attr->target_fd);
> +       if (IS_ERR(cgrp))
> +               return PTR_ERR(cgrp);
> +
> +       prog = bpf_prog_get_type(attr->attach_bpf_fd, ptype);
> +       if (IS_ERR(prog))
> +               prog = NULL;
> +
> +       ret = cgroup_bpf_detach(cgrp, prog, attr->attach_type, 0);
> +       if (prog)
> +               bpf_prog_put(prog);
> +       cgroup_put(cgrp);
> +       return ret;
> +}
> +
> +int cgroup_bpf_prog_query(const union bpf_attr *attr,
> +                         union bpf_attr __user *uattr)
> +{
> +       struct cgroup *cgrp;
> +       int ret;
> +
> +       cgrp = cgroup_get_from_fd(attr->query.target_fd);
> +       if (IS_ERR(cgrp))
> +               return PTR_ERR(cgrp);
> +       ret = cgroup_bpf_query(cgrp, attr, uattr);
> +       cgroup_put(cgrp);
> +       return ret;
> +}
> +
>  /**
>   * __cgroup_bpf_run_filter_skb() - Run a program for packet filtering
>   * @sk: The socket sending or receiving traffic
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index 0fa20624707f..52fa44856623 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -1489,65 +1489,14 @@ static int bpf_raw_tracepoint_open(const union bpf_attr *attr)
>         return err;
>  }
>
> -#ifdef CONFIG_CGROUP_BPF
> -
> -static 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;
> -       }
> -}
> -
>  #define BPF_PROG_ATTACH_LAST_FIELD attach_flags
>
> -static 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;
> -}
> -
>  #define BPF_F_ATTACH_MASK \
>         (BPF_F_ALLOW_OVERRIDE | BPF_F_ALLOW_MULTI)
>
>  static int bpf_prog_attach(const union bpf_attr *attr)
>  {
>         enum bpf_prog_type ptype;
> -       struct bpf_prog *prog;
> -       struct cgroup *cgrp;
> -       int ret;
>
>         if (!capable(CAP_NET_ADMIN))
>                 return -EPERM;
> @@ -1593,28 +1542,7 @@ static int bpf_prog_attach(const union bpf_attr *attr)
>                 return -EINVAL;
>         }
>
> -       prog = bpf_prog_get_type(attr->attach_bpf_fd, ptype);
> -       if (IS_ERR(prog))
> -               return PTR_ERR(prog);
> -
> -       if (bpf_prog_attach_check_attach_type(prog, attr->attach_type)) {
> -               bpf_prog_put(prog);
> -               return -EINVAL;
> -       }
> -
> -       cgrp = cgroup_get_from_fd(attr->target_fd);
> -       if (IS_ERR(cgrp)) {
> -               bpf_prog_put(prog);
> -               return PTR_ERR(cgrp);
> -       }
> -
> -       ret = cgroup_bpf_attach(cgrp, prog, attr->attach_type,
> -                               attr->attach_flags);
> -       if (ret)
> -               bpf_prog_put(prog);
> -       cgroup_put(cgrp);
> -
> -       return ret;
> +       return cgroup_bpf_prog_attach(attr, ptype);
>  }
>
>  #define BPF_PROG_DETACH_LAST_FIELD attach_type
> @@ -1622,9 +1550,6 @@ static int bpf_prog_attach(const union bpf_attr *attr)
>  static int bpf_prog_detach(const union bpf_attr *attr)
>  {
>         enum bpf_prog_type ptype;
> -       struct bpf_prog *prog;
> -       struct cgroup *cgrp;
> -       int ret;
>
>         if (!capable(CAP_NET_ADMIN))
>                 return -EPERM;
> @@ -1667,19 +1592,7 @@ static int bpf_prog_detach(const union bpf_attr *attr)
>                 return -EINVAL;
>         }
>
> -       cgrp = cgroup_get_from_fd(attr->target_fd);
> -       if (IS_ERR(cgrp))
> -               return PTR_ERR(cgrp);
> -
> -       prog = bpf_prog_get_type(attr->attach_bpf_fd, ptype);
> -       if (IS_ERR(prog))
> -               prog = NULL;
> -
> -       ret = cgroup_bpf_detach(cgrp, prog, attr->attach_type, 0);
> -       if (prog)
> -               bpf_prog_put(prog);
> -       cgroup_put(cgrp);
> -       return ret;
> +       return cgroup_bpf_prog_detach(attr, ptype);
>  }
>
>  #define BPF_PROG_QUERY_LAST_FIELD query.prog_cnt
> @@ -1687,9 +1600,6 @@ static int bpf_prog_detach(const union bpf_attr *attr)
>  static int bpf_prog_query(const union bpf_attr *attr,
>                           union bpf_attr __user *uattr)
>  {
> -       struct cgroup *cgrp;
> -       int ret;
> -
>         if (!capable(CAP_NET_ADMIN))
>                 return -EPERM;
>         if (CHECK_ATTR(BPF_PROG_QUERY))
> @@ -1717,14 +1627,9 @@ static int bpf_prog_query(const union bpf_attr *attr,
>         default:
>                 return -EINVAL;
>         }
> -       cgrp = cgroup_get_from_fd(attr->query.target_fd);
> -       if (IS_ERR(cgrp))
> -               return PTR_ERR(cgrp);
> -       ret = cgroup_bpf_query(cgrp, attr, uattr);
> -       cgroup_put(cgrp);
> -       return ret;
> +
> +       return cgroup_bpf_prog_query(attr, uattr);
>  }
> -#endif /* CONFIG_CGROUP_BPF */
>
>  #define BPF_PROG_TEST_RUN_LAST_FIELD test.duration
>
> @@ -2371,7 +2276,6 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz
>         case BPF_OBJ_GET:
>                 err = bpf_obj_get(&attr);
>                 break;
> -#ifdef CONFIG_CGROUP_BPF
>         case BPF_PROG_ATTACH:
>                 err = bpf_prog_attach(&attr);
>                 break;
> @@ -2381,7 +2285,6 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz
>         case BPF_PROG_QUERY:
>                 err = bpf_prog_query(&attr, uattr);
>                 break;
> -#endif
>         case BPF_PROG_TEST_RUN:
>                 err = bpf_prog_test_run(&attr, uattr);
>                 break;
> --
> 2.17.1
>