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authorMartin KaFai Lau <kafai@fb.com>2016-06-30 19:28:42 +0200
committerDavid S. Miller <davem@davemloft.net>2016-07-01 22:30:38 +0200
commit1f3fe7ebf6136c341012db9f554d4caa566fcbaa (patch)
treeec78d296ec21640777ed39c1277fa7b5b88e4169 /kernel
parentMerge branch 'bpf-robustify' (diff)
downloadlinux-1f3fe7ebf6136c341012db9f554d4caa566fcbaa.tar.xz
linux-1f3fe7ebf6136c341012db9f554d4caa566fcbaa.zip
cgroup: Add cgroup_get_from_fd
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 <kafai@fb.com> Cc: Alexei Starovoitov <ast@fb.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Tejun Heo <tj@kernel.org> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/cgroup.c35
1 files changed, 35 insertions, 0 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 75c0ff00aca6..50787cd61da2 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>
/*
@@ -6209,6 +6210,40 @@ struct cgroup *cgroup_get_from_path(const char *path)
}
EXPORT_SYMBOL_GPL(cgroup_get_from_path);
+/**
+ * cgroup_get_from_fd - get a cgroup pointer from a fd
+ * @fd: fd obtained by open(cgroup2_dir)
+ *
+ * Find the cgroup from a fd which should be obtained
+ * by opening a cgroup directory. Returns a pointer to the
+ * cgroup on success. ERR_PTR is returned if the cgroup
+ * cannot be found.
+ */
+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 ERR_PTR(-EBADF);
+
+ 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(-EBADF);
+ }
+
+ 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.