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authorChristian Brauner <christian.brauner@ubuntu.com>2020-02-05 14:26:21 +0100
committerTejun Heo <tj@kernel.org>2020-02-12 17:57:51 -0500
commitf3553220d4cc458d69f7da6e71a3a6097778bd28 (patch)
tree8b1323e0a992356c6999df4ea5fdc19e6850cedb /kernel/cgroup
parent5a5cf5cb30d7815c01035fde4b84edef85d11c68 (diff)
downloadlwn-f3553220d4cc458d69f7da6e71a3a6097778bd28.tar.gz
lwn-f3553220d4cc458d69f7da6e71a3a6097778bd28.zip
cgroup: add cgroup_may_write() helper
Add a cgroup_may_write() helper which we can use in the CLONE_INTO_CGROUP patch series to verify that we can write to the destination cgroup. Cc: Tejun Heo <tj@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Li Zefan <lizefan@huawei.com> Cc: cgroups@vger.kernel.org Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel/cgroup')
-rw-r--r--kernel/cgroup/cgroup.c24
1 files changed, 17 insertions, 7 deletions
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 502769b2683c..6d8bdddd8c28 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -4654,13 +4654,28 @@ static int cgroup_procs_show(struct seq_file *s, void *v)
return 0;
}
+static int cgroup_may_write(const struct cgroup *cgrp, struct super_block *sb)
+{
+ int ret;
+ struct inode *inode;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ inode = kernfs_get_inode(sb, cgrp->procs_file.kn);
+ if (!inode)
+ return -ENOMEM;
+
+ ret = inode_permission(inode, MAY_WRITE);
+ iput(inode);
+ return ret;
+}
+
static int cgroup_procs_write_permission(struct cgroup *src_cgrp,
struct cgroup *dst_cgrp,
struct super_block *sb)
{
struct cgroup_namespace *ns = current->nsproxy->cgroup_ns;
struct cgroup *com_cgrp = src_cgrp;
- struct inode *inode;
int ret;
lockdep_assert_held(&cgroup_mutex);
@@ -4670,12 +4685,7 @@ static int cgroup_procs_write_permission(struct cgroup *src_cgrp,
com_cgrp = cgroup_parent(com_cgrp);
/* %current should be authorized to migrate to the common ancestor */
- inode = kernfs_get_inode(sb, com_cgrp->procs_file.kn);
- if (!inode)
- return -ENOMEM;
-
- ret = inode_permission(inode, MAY_WRITE);
- iput(inode);
+ ret = cgroup_may_write(com_cgrp, sb);
if (ret)
return ret;