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authorDaniel Mack <daniel@zonque.org>2016-11-23 16:52:27 +0100
committerDavid S. Miller <davem@davemloft.net>2016-11-25 16:26:04 -0500
commitf4324551489e8781d838f941b7aee4208e52e8bf (patch)
treee7ade301a580bb2165560e7dcf8158b7e37767ee /kernel/bpf
parent3007098494bec614fb55dee7bc0410bb7db5ad18 (diff)
downloadlinux-f4324551489e8781d838f941b7aee4208e52e8bf.tar.bz2
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')
-rw-r--r--kernel/bpf/syscall.c81
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;