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Subject[PATCH 06/13] cgroup: update cgroup name handling
Date
Straightforward updates to cgroup name handling in preparation of
kernfs conversion.

* cgroup_alloc_name() is updated to take const char * isntead of
dentry * for name source.

* cgroup name formatting is separated out into cgroup_file_name().
While at it, buffer length protection is added.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
kernel/cgroup.c | 35 ++++++++++++++++++++++-------------
1 file changed, 22 insertions(+), 13 deletions(-)

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 8a9548c..3cef4a3 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -67,6 +67,9 @@
*/
#define CGROUP_PIDLIST_DESTROY_DELAY HZ

+#define CGROUP_FILE_NAME_MAX (MAX_CGROUP_TYPE_NAMELEN + \
+ MAX_CFTYPE_NAME + 2)
+
/*
* cgroup_tree_mutex nests above cgroup_mutex and protects cftypes, file
* creation/removal and hierarchy changing operations including cgroup
@@ -799,17 +802,29 @@ static struct inode *cgroup_new_inode(umode_t mode, struct super_block *sb)
return inode;
}

-static struct cgroup_name *cgroup_alloc_name(struct dentry *dentry)
+static struct cgroup_name *cgroup_alloc_name(const char *name_str)
{
struct cgroup_name *name;

- name = kmalloc(sizeof(*name) + dentry->d_name.len + 1, GFP_KERNEL);
+ name = kmalloc(sizeof(*name) + strlen(name_str) + 1, GFP_KERNEL);
if (!name)
return NULL;
- strcpy(name->name, dentry->d_name.name);
+ strcpy(name->name, name_str);
return name;
}

+static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft,
+ char *buf)
+{
+ if (cft->ss && !(cft->flags & CFTYPE_NO_PREFIX) &&
+ !(cgrp->root->flags & CGRP_ROOT_NOPREFIX))
+ snprintf(buf, CGROUP_FILE_NAME_MAX, "%s.%s",
+ cft->ss->name, cft->name);
+ else
+ strncpy(buf, cft->name, CGROUP_FILE_NAME_MAX);
+ return buf;
+}
+
static void cgroup_free_fn(struct work_struct *work)
{
struct cgroup *cgrp = container_of(work, struct cgroup, destroy_work);
@@ -2435,7 +2450,7 @@ static int cgroup_rename(struct inode *old_dir, struct dentry *old_dentry,
if (cgroup_sane_behavior(cgrp))
return -EPERM;

- name = cgroup_alloc_name(new_dentry);
+ name = cgroup_alloc_name(new_dentry->d_name.name);
if (!name)
return -ENOMEM;

@@ -2611,14 +2626,7 @@ static int cgroup_add_file(struct cgroup *cgrp, struct cftype *cft)
struct cfent *cfe;
int error;
umode_t mode;
- char name[MAX_CGROUP_TYPE_NAMELEN + MAX_CFTYPE_NAME + 2] = { 0 };
-
- if (cft->ss && !(cft->flags & CFTYPE_NO_PREFIX) &&
- !(cgrp->root->flags & CGRP_ROOT_NOPREFIX)) {
- strcpy(name, cft->ss->name);
- strcat(name, ".");
- }
- strcat(name, cft->name);
+ char name[CGROUP_FILE_NAME_MAX];

BUG_ON(!mutex_is_locked(&dir->d_inode->i_mutex));

@@ -2626,6 +2634,7 @@ static int cgroup_add_file(struct cgroup *cgrp, struct cftype *cft)
if (!cfe)
return -ENOMEM;

+ cgroup_file_name(cgrp, cft, name);
dentry = lookup_one_len(name, dir, strlen(name));
if (IS_ERR(dentry)) {
error = PTR_ERR(dentry);
@@ -4133,7 +4142,7 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
if (!cgrp)
return -ENOMEM;

- name = cgroup_alloc_name(dentry);
+ name = cgroup_alloc_name(dentry->d_name.name);
if (!name) {
err = -ENOMEM;
goto err_free_cgrp;
--
1.8.5.3


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