Add a helper function to get a cgroup2 from a fd. It will be
stored in a bpf array (BPF_MAP_TYPE_CGROUP_ARRAY) which will
be introduced in the later patch.
Signed-off-by: Martin KaFai Lau <ka...@fb.com>
Cc: Alexei Starovoitov <a...@fb.com>
Cc: Daniel Borkmann <dan...@iogearbox.net>
Cc: Tejun Heo <t...@kernel.org>
---
include/linux/cgroup.h | 1 +
kernel/cgroup.c | 26 ++++++++++++++++++++++++++
2 files changed, 27 insertions(+)
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index a20320c..984f73b 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -87,6 +87,7 @@ struct cgroup_subsys_state *css_tryget_online_from_dir(struct
dentry *dentry,
struct cgroup_subsys
*ss);
struct cgroup *cgroup_get_from_path(const char *path);
+struct cgroup *cgroup_get_from_fd(int fd);
int cgroup_attach_task_all(struct task_struct *from, struct task_struct *);
int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from);
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 86cb5c6..616c751 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -62,6 +62,7 @@
#include <linux/proc_ns.h>
#include <linux/nsproxy.h>
#include <linux/proc_ns.h>
+#include <linux/file.h>
#include <net/sock.h>
/*
@@ -6205,6 +6206,31 @@ struct cgroup *cgroup_get_from_path(const char *path)
}
EXPORT_SYMBOL_GPL(cgroup_get_from_path);
+struct cgroup *cgroup_get_from_fd(int fd)
+{
+ struct cgroup_subsys_state *css;
+ struct cgroup *cgrp;
+ struct file *f;
+
+ f = fget_raw(fd);
+ if (!f)
+ return NULL;
+
+ css = css_tryget_online_from_dir(f->f_path.dentry, NULL);
+ fput(f);
+ if (IS_ERR(css))
+ return ERR_CAST(css);
+
+ cgrp = css->cgroup;
+ if (!cgroup_on_dfl(cgrp)) {
+ cgroup_put(cgrp);
+ return ERR_PTR(-EINVAL);
+ }
+
+ return cgrp;
+}
+EXPORT_SYMBOL_GPL(cgroup_get_from_fd);
+
/*
* sock->sk_cgrp_data handling. For more info, see sock_cgroup_data
* definition in cgroup-defs.h.
--
2.5.1
