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bpf: add BPF_PROG_ATTACH and BPF_PROG_DETACH commands

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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>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Daniel Mack
2016-11-23 16:52:27 +01:00
committed by David S. Miller
parent 3007098494
commit f432455148
2 changed files with 89 additions and 0 deletions
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8
include/uapi/linux/bpf.h
View File

@@ -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 {
@@ -159,6 +161,12 @@ 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;
};
} __attribute__((aligned(8)));
/* BPF helper function descriptions: