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author | Daniel Mack <daniel@zonque.org> | 2016-11-23 16:52:27 +0100 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2016-11-25 16:26:04 -0500 |
commit | f4324551489e8781d838f941b7aee4208e52e8bf (patch) | |
tree | e7ade301a580bb2165560e7dcf8158b7e37767ee /kernel/bpf/syscall.c | |
parent | 3007098494bec614fb55dee7bc0410bb7db5ad18 (diff) | |
download | linux-f4324551489e8781d838f941b7aee4208e52e8bf.tar.gz linux-f4324551489e8781d838f941b7aee4208e52e8bf.tar.bz2 linux-f4324551489e8781d838f941b7aee4208e52e8bf.zip |
bpf: add BPF_PROG_ATTACH and BPF_PROG_DETACH commands
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>
Diffstat (limited to 'kernel/bpf/syscall.c')
-rw-r--r-- | kernel/bpf/syscall.c | 81 |
1 files changed, 81 insertions, 0 deletions
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index eb15498b8d55..1090d16a31c1 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -835,6 +835,77 @@ static int bpf_obj_get(const union bpf_attr *attr) return bpf_obj_get_user(u64_to_user_ptr(attr->pathname)); } +#ifdef CONFIG_CGROUP_BPF + +#define BPF_PROG_ATTACH_LAST_FIELD attach_type + +static int bpf_prog_attach(const union bpf_attr *attr) +{ + struct bpf_prog *prog; + struct cgroup *cgrp; + + if (!capable(CAP_NET_ADMIN)) + return -EPERM; + + if (CHECK_ATTR(BPF_PROG_ATTACH)) + return -EINVAL; + + switch (attr->attach_type) { + case BPF_CGROUP_INET_INGRESS: + case BPF_CGROUP_INET_EGRESS: + prog = bpf_prog_get_type(attr->attach_bpf_fd, + BPF_PROG_TYPE_CGROUP_SKB); + 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; +} + +#define BPF_PROG_DETACH_LAST_FIELD attach_type + +static int bpf_prog_detach(const union bpf_attr *attr) +{ + struct cgroup *cgrp; + + if (!capable(CAP_NET_ADMIN)) + return -EPERM; + + if (CHECK_ATTR(BPF_PROG_DETACH)) + return -EINVAL; + + switch (attr->attach_type) { + case BPF_CGROUP_INET_INGRESS: + case BPF_CGROUP_INET_EGRESS: + 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 = {}; @@ -901,6 +972,16 @@ 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; |