From: Daniel Borkmann <daniel@iogearbox•net>
To: Daniel Mack <daniel@zonque•org>, htejun@fb•com, ast@fb•com
Cc: davem@davemloft•net, kafai@fb•com, fw@strlen•de,
pablo@netfilter•org, harald@redhat•com, netdev@vger•kernel.org,
sargun@sargun•me
Subject: Re: [PATCH v3 3/6] bpf: add BPF_PROG_ATTACH and BPF_PROG_DETACH commands
Date: Tue, 30 Aug 2016 01:00:07 +0200 [thread overview]
Message-ID: <57C4BE77.8070309@iogearbox.net> (raw)
In-Reply-To: <1472241532-11682-4-git-send-email-daniel@zonque.org>
On 08/26/2016 09:58 PM, Daniel Mack wrote:
> Extend the bpf(2) syscall by two new commands, BPF_PROG_ATTACH and
> BPF_PROG_DETACH which allow attaching and detaching eBPF programs
> to a target.
>
> On the API level, the target could be anything that has an fd in
> userspace, hence the name of the field in union bpf_attr is called
> 'target_fd'.
>
> When called with BPF_ATTACH_TYPE_CGROUP_INET_{E,IN}GRESS, the target is
> expected to be a valid file descriptor of a cgroup v2 directory which
> has the bpf controller enabled. These are the only use-cases
> implemented by this patch at this point, but more can be added.
>
> If a program of the given type already exists in the given cgroup,
> the program is swapped automically, so userspace does not have to drop
> an existing program first before installing a new one, which would
> otherwise leave a gap in which no program is attached.
>
> For more information on the propagation logic to subcgroups, please
> refer to the bpf cgroup controller implementation.
>
> The API is guarded by CAP_NET_ADMIN.
>
> Signed-off-by: Daniel Mack <daniel@zonque•org>
> syscall
^^^ slipped in?
> ---
> include/uapi/linux/bpf.h | 9 ++++++
> kernel/bpf/syscall.c | 83 ++++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 92 insertions(+)
>
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index 1d5db42..4cc2dcf 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -73,6 +73,8 @@ enum bpf_cmd {
> BPF_PROG_LOAD,
> BPF_OBJ_PIN,
> BPF_OBJ_GET,
> + BPF_PROG_ATTACH,
> + BPF_PROG_DETACH,
> };
>
> enum bpf_map_type {
> @@ -147,6 +149,13 @@ union bpf_attr {
> __aligned_u64 pathname;
> __u32 bpf_fd;
> };
> +
> + struct { /* anonymous struct used by BPF_PROG_ATTACH/DETACH commands */
> + __u32 target_fd; /* container object to attach to */
> + __u32 attach_bpf_fd; /* eBPF program to attach */
> + __u32 attach_type; /* BPF_ATTACH_TYPE_* */
> + __u64 attach_flags;
Could we just do ...
__u32 dst_fd;
__u32 src_fd;
__u32 attach_type;
... and leave flags out, since unused anyway? Also see below.
> + };
> } __attribute__((aligned(8)));
>
> /* integer value in 'imm' field of BPF_CALL instruction selects which helper
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index 228f962..cc4d603 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -822,6 +822,79 @@ static int bpf_obj_get(const union bpf_attr *attr)
> return bpf_obj_get_user(u64_to_ptr(attr->pathname));
> }
>
> +#ifdef CONFIG_CGROUP_BPF
#define BPF_PROG_ATTACH_LAST_FIELD attach_type
#define BPF_PROG_DETACH_LAST_FIELD BPF_PROG_ATTACH_LAST_FIELD
> +static int bpf_prog_attach(const union bpf_attr *attr)
> +{
> + struct bpf_prog *prog;
> +
> + if (!capable(CAP_NET_ADMIN))
> + return -EPERM;
> +
> + /* Flags are unused for now */
> + if (attr->attach_flags != 0)
> + return -EINVAL;
Correct way would be to:
if (CHECK_ATTR(BPF_PROG_ATTACH))
return -EINVAL;
> +
> + switch (attr->attach_type) {
> + case BPF_ATTACH_TYPE_CGROUP_INET_INGRESS:
> + case BPF_ATTACH_TYPE_CGROUP_INET_EGRESS: {
> + struct cgroup *cgrp;
> +
> + prog = bpf_prog_get_type(attr->attach_bpf_fd,
> + BPF_PROG_TYPE_CGROUP_SOCKET_FILTER);
> + if (IS_ERR(prog))
> + return PTR_ERR(prog);
> +
> + cgrp = cgroup_get_from_fd(attr->target_fd);
> + if (IS_ERR(cgrp)) {
> + bpf_prog_put(prog);
> + return PTR_ERR(cgrp);
> + }
> +
> + cgroup_bpf_update(cgrp, prog, attr->attach_type);
> + cgroup_put(cgrp);
> +
> + break;
> + }
> +
> + default:
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
> +
> +static int bpf_prog_detach(const union bpf_attr *attr)
> +{
> + if (!capable(CAP_NET_ADMIN))
> + return -EPERM;
> +
> + /* Flags are unused for now */
> + if (attr->attach_flags != 0)
> + return -EINVAL;
if (CHECK_ATTR(BPF_PROG_DETACH))
return -EINVAL;
> + switch (attr->attach_type) {
> + case BPF_ATTACH_TYPE_CGROUP_INET_INGRESS:
> + case BPF_ATTACH_TYPE_CGROUP_INET_EGRESS: {
> + struct cgroup *cgrp;
> +
> + cgrp = cgroup_get_from_fd(attr->target_fd);
> + if (IS_ERR(cgrp))
> + return PTR_ERR(cgrp);
> +
> + cgroup_bpf_update(cgrp, NULL, attr->attach_type);
> + cgroup_put(cgrp);
> +
> + break;
> + }
> +
> + default:
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
> +#endif /* CONFIG_CGROUP_BPF */
> +
> SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, size)
> {
> union bpf_attr attr = {};
> @@ -888,6 +961,16 @@ 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;
> + case BPF_PROG_DETACH:
> + err = bpf_prog_detach(&attr);
> + break;
> +#endif
> +
> default:
> err = -EINVAL;
> break;
>
next prev parent reply other threads:[~2016-08-29 23:00 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-26 19:58 [PATCH v3 0/6] Add eBPF hooks for cgroups Daniel Mack
2016-08-26 19:58 ` [PATCH v3 1/6] bpf: add new prog type for cgroup socket filtering Daniel Mack
2016-08-29 22:14 ` Daniel Borkmann
2016-09-05 12:48 ` Daniel Mack
2016-08-26 19:58 ` [PATCH v3 2/6] cgroup: add support for eBPF programs Daniel Mack
2016-08-27 0:03 ` Alexei Starovoitov
2016-09-05 12:47 ` Daniel Mack
2016-08-29 22:42 ` Daniel Borkmann
2016-09-05 12:50 ` Daniel Mack
2016-08-29 23:04 ` Sargun Dhillon
2016-09-05 14:49 ` Daniel Mack
2016-09-05 21:40 ` Sargun Dhillon
2016-09-05 22:39 ` Alexei Starovoitov
2016-08-26 19:58 ` [PATCH v3 3/6] bpf: add BPF_PROG_ATTACH and BPF_PROG_DETACH commands Daniel Mack
2016-08-27 0:08 ` Alexei Starovoitov
2016-09-05 12:56 ` Daniel Mack
2016-09-05 15:30 ` David Laight
2016-09-05 15:40 ` Daniel Mack
2016-09-05 17:29 ` Joe Perches
2016-08-29 23:00 ` Daniel Borkmann [this message]
2016-09-05 12:54 ` Daniel Mack
2016-09-05 13:56 ` Daniel Borkmann
2016-09-05 14:09 ` Daniel Mack
2016-09-05 17:09 ` Daniel Borkmann
2016-09-05 18:32 ` Alexei Starovoitov
2016-09-05 18:43 ` Daniel Mack
2016-08-26 19:58 ` [PATCH v3 4/6] net: filter: run cgroup eBPF ingress programs Daniel Mack
2016-08-29 23:15 ` Daniel Borkmann
2016-08-26 19:58 ` [PATCH v3 5/6] net: core: run cgroup eBPF egress programs Daniel Mack
2016-08-29 22:03 ` Daniel Borkmann
2016-08-29 22:23 ` Sargun Dhillon
2016-09-05 14:22 ` Daniel Mack
2016-09-06 17:14 ` Daniel Borkmann
2016-08-26 19:58 ` [PATCH v3 6/6] samples: bpf: add userspace example for attaching eBPF programs to cgroups Daniel Mack
2016-08-27 13:00 ` [PATCH v3 0/6] Add eBPF hooks for cgroups Rami Rosen
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